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 <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>As filed with the Securities and Exchange Commission on November 30, 2022 </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="right"><B>Registration
<FONT STYLE="white-space:nowrap">No.&nbsp;333-&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</FONT> </B></P> <P STYLE="font-size:4pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="line-height:1.0pt;margin-top:0pt;margin-bottom:0pt;border-bottom:1px solid #000000">&nbsp;</P> <P STYLE="line-height:3.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1px solid #000000">&nbsp;</P>
<P STYLE="margin-top:4pt; margin-bottom:0pt; font-size:18pt; font-family:Times New Roman" ALIGN="center"><B>UNITED STATES </B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:18pt; font-family:Times New Roman" ALIGN="center"><B>SECURITIES
AND EXCHANGE COMMISSION </B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:12pt; font-family:Times New Roman" ALIGN="center"><B>WASHINGTON, DC 20549 </B></P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P><center>
<P STYLE="line-height:6.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1.00pt solid #000000;width:21%">&nbsp;</P></center> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:18pt; font-family:Times New Roman" ALIGN="center"><B><FONT
STYLE="white-space:nowrap">FORM&nbsp;S-8</FONT> </B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:18pt; font-family:Times New Roman" ALIGN="center"><B>REGISTRATION STATEMENT </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:12pt; font-family:Times New Roman" ALIGN="center"><B><I>UNDER </I></B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:12pt; font-family:Times New Roman" ALIGN="center"><B><I>THE
SECURITIES ACT OF 1933 </I></B></P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P><center> <P STYLE="line-height:6.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1.00pt solid #000000;width:21%">&nbsp;</P></center>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:24pt; font-family:Times New Roman" ALIGN="center"><B>MERRIMACK PHARMACEUTICALS, INC. </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>(Exact Name of Registrant as Specified in Its Charter) </B></P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P><center>
<P STYLE="line-height:6.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1.00pt solid #000000;width:21%">&nbsp;</P></center> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TD VALIGN="top" ALIGN="center"><B>Delaware</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top" ALIGN="center"><B><FONT STYLE="white-space:nowrap">04-3210530</FONT></B></TD></TR>
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<TD VALIGN="top" ALIGN="center"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>(State or Other Jurisdiction of</B></P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>Incorporation or Organization)</B></P></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top" ALIGN="center"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>(I.R.S. Employer</B></P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>Identification No.)</B></P></TD></TR>
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<TD HEIGHT="16" COLSPAN="2"></TD></TR>
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<TD VALIGN="top" ALIGN="center"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>One Broadway, 14th Floor</B></P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Cambridge, MA</B></P></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>02142</B></TD></TR>
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<TD VALIGN="top" ALIGN="center"><B>(Address of Principal Executive Offices)</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top" ALIGN="center"><B>(Zip Code)</B></TD></TR>
</TABLE> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>2021 Incentive Award Plan </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>(Full Title of the Plan) </B></P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Gary L. Crocker </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>President </B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Merrimack
Pharmaceuticals, Inc. </B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>One Broadway, 14th Floor </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Cambridge, Massachusetts 02142 </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>(Name and Address of Agent for Service) </B></P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B><FONT STYLE="white-space:nowrap">(617)&nbsp;720-8616</FONT> </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>(Telephone Number, Including Area Code, of Agent for Service) </B></P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P><center> <P STYLE="line-height:6.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1.00pt solid #000000;width:21%">&nbsp;</P></center>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer,
<FONT STYLE="white-space:nowrap">a&nbsp;non-accelerated&nbsp;filer,</FONT> a smaller reporting company or an emerging growth company. See the definitions of &#147;large accelerated filer,&#148; &#147;accelerated filer,&#148; &#147;smaller reporting
company,&#148; and &#147;emerging growth company&#148; in <FONT STYLE="white-space:nowrap">Rule&nbsp;12b-2&nbsp;of</FONT> the Exchange Act. </P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TD VALIGN="bottom">Large&nbsp;accelerated&nbsp;filer</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom">&#9744;</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom">Smaller&nbsp;Reporting&nbsp;Company&nbsp;&#9746;</TD></TR>
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<TD VALIGN="bottom">Accelerated&nbsp;filer</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom">&#9744;</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom">Emerging&nbsp;growth&nbsp;company&nbsp;&nbsp;&nbsp;&#9744;</TD></TR>
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<TD VALIGN="bottom"><FONT STYLE="white-space:nowrap">Non-accelerated</FONT> filer</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom">&#9746;</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
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</TABLE> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period
for complying with any new or revised financial accounting standards provided pursuant to Section&nbsp;7(a)(2)(B) of the Securities Act.&nbsp;&nbsp;&#9744; </P> <P STYLE="font-size:10pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="line-height:1.0pt;margin-top:0pt;margin-bottom:0pt;border-bottom:1px solid #000000">&nbsp;</P> <P STYLE="line-height:3.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1px solid #000000">&nbsp;</P>
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 <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>PART I </B></P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>INFORMATION REQUIRED IN THE SECTION 1O(A) PROSPECTUS </B></P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">The documents containing the information specified in this Part I will be delivered to the participants holding the equity awards covered by
this registration statement on Form <FONT STYLE="white-space:nowrap">S-8</FONT> (the &#147;Registration Statement&#148;) as required by Rule 428(b)(1) of the Securities Act of 1933, as amended (the &#147;Securities Act&#148;). Such documents are not
required to be filed with the Securities and Exchange Commission (the &#147;Commission&#148;) as part of this Registration Statement. </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">The Company will
furnish without charge to each person to whom documents containing the information specified in this Part I will be delivered, upon the written or oral request of such person, a copy of any and all of the documents incorporated by reference in Item
3 of Part II of this Registration Statement, other than exhibits to such documents (unless such exhibits are specifically incorporated by reference to the information that is incorporated) and any other documents required to be delivered pursuant to
Rule 428(b). Those documents are incorporated by reference in the Section&nbsp;10(a) prospectus. Requests should be directed to: Merrimack Pharmaceuticals, Inc. One Broadway, 14th Floor, Cambridge, Massachusetts 02142
<FONT STYLE="white-space:nowrap">(617)&nbsp;441-1000.</FONT> </P> <P STYLE="margin-top:24pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>PART II </B></P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>INFORMATION REQUIRED IN THE REGISTRATION STATEMENT </B></P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><B>Item&nbsp;3. Incorporation of Documents by Reference. </B></P>
<P STYLE="margin-top:6pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Merrimack Pharmaceuticals, Inc. (the &#147;Registrant&#148;) hereby incorporates by reference into this Registration Statement the following documents
previously filed with the Commission pursuant to the Securities Exchange Act of 1934, as amended (the &#147;Exchange Act&#148;): </P> <P STYLE="font-size:6pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TD WIDTH="4%">&nbsp;</TD>
<TD WIDTH="5%" VALIGN="top" ALIGN="left">&#149;</TD>
<TD ALIGN="left" VALIGN="top"> <P STYLE=" margin-top:0pt ; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman; " ALIGN="left">The Registrant&#146;s Annual Report on <A HREF="http://www.sec.gov/Archives/edgar/data/../../../ix?doc=/Archives/edgar/data/1274792/000156459022009320/mack-10k_20211231.htm">Form
 <FONT STYLE="white-space:nowrap">10-K</FONT></A> for the fiscal year ended December&nbsp;31, 2021 filed with the Commission on March&nbsp;9, 2022, which contains audited consolidated financial statements for the most recent fiscal year for which
such statements have been filed; </P></TD></TR></TABLE> <P STYLE="font-size:6pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TR style = "page-break-inside:avoid">
<TD WIDTH="4%">&nbsp;</TD>
<TD WIDTH="5%" VALIGN="top" ALIGN="left">&#149;</TD>
<TD ALIGN="left" VALIGN="top"> <P STYLE=" margin-top:0pt ; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman; " ALIGN="left">The Registrant&#146;s Quarterly Reports on Form <FONT STYLE="white-space:nowrap">10-Q</FONT> for the fiscal
quarters ended&nbsp;March 31, 2022, June&nbsp;30, 2022 and September&nbsp;30, 2022, filed on <A HREF="http://www.sec.gov/Archives/edgar/data/../../../ix?doc=/Archives/edgar/data/1274792/000156459022018284/mack-10q_20220331.htm">May&nbsp;5, 2022</A>,
<A HREF="http://www.sec.gov/Archives/edgar/data/../../../ix?doc=/Archives/edgar/data/1274792/000156459022028022/mack-10q_20220630.htm">August&nbsp;
4, 2022</A> and <A HREF="http://www.sec.gov/Archives/edgar/data/../../../ix?doc=/Archives/edgar/data/1274792/000095017022021933/mack-20220930.htm">November&nbsp;3, 2022</A>, respectively; </P></TD></TR></TABLE>
<P STYLE="font-size:6pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TR style = "page-break-inside:avoid">
<TD WIDTH="4%">&nbsp;</TD>
<TD WIDTH="5%" VALIGN="top" ALIGN="left">&#149;</TD>
<TD ALIGN="left" VALIGN="top"> <P STYLE=" margin-top:0pt ; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman; " ALIGN="left">The Registrant&#146;s Current Reports on Form <FONT STYLE="white-space:nowrap">8-K</FONT> filed on <A HREF="http://www.sec.gov/Archives/edgar/data/../../../ix?doc=/Archives/edgar/data/1274792/000119312522276935/d260508d8k.htm">November&nbsp;3,
 2022</A> and <A HREF="http://www.sec.gov/Archives/edgar/data/../../../ix?doc=/Archives/edgar/data/1274792/000119312522280787/d418392d8k.htm">November&nbsp;9, 2022</A> (other than information &#147;furnished&#148; under Items 2.02 or 7.01, or
corresponding information furnished under Item 9.01 or included as an exhibit); and </P></TD></TR></TABLE> <P STYLE="font-size:6pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TR style = "page-break-inside:avoid">
<TD WIDTH="4%">&nbsp;</TD>
<TD WIDTH="5%" VALIGN="top" ALIGN="left">&#149;</TD>
<TD ALIGN="left" VALIGN="top"> <P STYLE=" margin-top:0pt ; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman; " ALIGN="left">The description of the Registrant&#146;s Common Stock on <A HREF="http://www.sec.gov/Archives/edgar/data/1274792/000110465912004686/a11-15435_98a12b.htm">Form
 <FONT STYLE="white-space:nowrap">8-A</FONT></A> filed with the Commission on January&nbsp;27, 2012 pursuant to Section&nbsp;12(b) of the Exchange Act, including any amendment or report filed for the purpose of updating such description.
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 <P STYLE="margin-top:0pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">All documents, reports and definitive proxy or information statements filed by the
Registrant on or after the date of this Registration Statement pursuant to Sections 13(a), 13(c), 14 and 15(d) of the Exchange Act (other than Current Reports furnished under Item 2.02 or Item 7.01 of Form <FONT STYLE="white-space:nowrap">8-K</FONT>
and exhibits furnished on such form that relate to such items), shall be deemed incorporated by reference in this Registration Statement and to be a part hereof from the date of filing such documents until a post-effective amendment of this
Registration Statement is filed which indicates that all securities being offered hereby have been sold or which deregisters all securities then remaining unsold. </P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">Any statement contained in a document incorporated or deemed to be incorporated by reference herein shall be deemed to be modified or
superseded for purposes of this Registration Statement to the extent that a statement contained herein or in any subsequently filed document that also is deemed to be incorporated by reference herein modifies or supersedes such statement. Any such
statement so modified or superseded shall not be deemed, except as so modified or superseded, to constitute a part of this Registration Statement. </P>
<P STYLE="margin-top:18pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><B>Item&nbsp;4. Description of Securities. </B></P> <P STYLE="margin-top:6pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Not applicable.
</P> <P STYLE="margin-top:18pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><B>Item&nbsp;5. Interests of Named Experts and Counsel. </B></P>
<P STYLE="margin-top:6pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">None. </P> <P STYLE="margin-top:18pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><B>Item&nbsp;6. Indemnification of Directors and
Officers. </B></P> <P STYLE="margin-top:6pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">Section&nbsp;102(b)(7) of the General Corporation Law of the State of Delaware (the &#147;DGCL&#148;) generally permits a
corporation to provide in its certificate of incorporation that a director or officer of the corporation shall not be personally liable to the corporation or its stockholders for monetary damages for breach of fiduciary duty as a director or
officer, except for liability for (i)&nbsp;with respect to directors and officers, any breach of the director&#146;s or officer&#146;s duty of loyalty to the corporation or its stockholders, (ii)&nbsp;with respect to directors and officers, acts or
omissions not in good faith or which involve intentional misconduct or a knowing violation of law, (iii)&nbsp;with respect to directors, payments of unlawful dividends or unlawful stock repurchases or redemptions under Section&nbsp;174 of the DGCL,
(iv)&nbsp;with respect to directors and officers, any transaction from which the director or officer derived an improper personal benefit, or (v)&nbsp;with respect to officers, any action by or in the right of the corporation. </P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">Section&nbsp;145 of the DGCL provides that a corporation may indemnify any person who is or was a director, officer, employee or agent of the
corporation (or is or was serving at the request of the corporation as a director, officer, employee or agent of another corporation, partnership, joint venture, trust or other enterprise), against expenses (including attorneys&#146; fees),
judgments, fines, and settlement amounts actually and reasonably incurred in connection with specified actions, suits, or proceedings brought by third parties, whether civil, criminal, administrative, or investigative (collectively,
&#147;Proceedings&#148;), if the individuals acted in good faith and in a manner they reasonably believed to be in or not opposed to the best interests of the corporation, and, with respect to any criminal action or proceeding, had no reasonable
cause to believe their conduct was unlawful. A similar standard is applicable in the case of derivative actions and actions brought directly by the corporation, except that indemnification only extends to expenses (including attorneys&#146; fees)
actually and reasonably incurred in connection with the defense or settlement of such actions, and the statute requires court approval before there can be any indemnification of such expenses if the person seeking indemnification has been found
liable to the corporation. </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">Additionally, among other things, Section&nbsp;145 of the DGCL generally: </P>
<P STYLE="font-size:6pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TD ALIGN="left" VALIGN="top"> <P ALIGN="left" STYLE=" margin-top:0pt ; margin-bottom:0pt; font-family:Times New Roman; font-size:10pt">requires indemnification against expenses (including attorneys&#146; fees) actually and reasonably incurred by
directors and officers, and permits the same for other employees and agents, to the extent they have been successful, on the merits or otherwise, in defending an action, suit, or proceeding or in defense of any claim, issue or matter therein
(whether brought by a third party or by or on behalf of the corporation); </P></TD></TR></TABLE>
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<TD WIDTH="10%">&nbsp;</TD>
<TD WIDTH="2%" VALIGN="top" ALIGN="left">&#149;</TD>
<TD WIDTH="1%" VALIGN="top">&nbsp;</TD>
<TD ALIGN="left" VALIGN="top"> <P ALIGN="left" STYLE=" margin-top:0pt ; margin-bottom:0pt; font-family:Times New Roman; font-size:10pt">permits a corporation to pay expenses of defense in advance of the final disposition of an action, suit, or
proceeding upon receipt (in the case of a current director or officer) of an undertaking to repay any amounts advanced if it is ultimately determined that the director or officer is not entitled to be indemnified; </P></TD></TR></TABLE>
<P STYLE="font-size:6pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR style = "page-break-inside:avoid">
<TD WIDTH="10%">&nbsp;</TD>
<TD WIDTH="2%" VALIGN="top" ALIGN="left">&#149;</TD>
<TD WIDTH="1%" VALIGN="top">&nbsp;</TD>
<TD ALIGN="left" VALIGN="top"> <P ALIGN="left" STYLE=" margin-top:0pt ; margin-bottom:0pt; font-family:Times New Roman; font-size:10pt">provides that it is not exclusive of other indemnification and advancement of expenses that may be granted by a
corporation&#146;s bylaws, disinterested director vote, stockholder vote, agreement, or otherwise; and </P></TD></TR></TABLE> <P STYLE="font-size:6pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR style = "page-break-inside:avoid">
<TD WIDTH="10%">&nbsp;</TD>
<TD WIDTH="2%" VALIGN="top" ALIGN="left">&#149;</TD>
<TD WIDTH="1%" VALIGN="top">&nbsp;</TD>
<TD ALIGN="left" VALIGN="top"> <P ALIGN="left" STYLE=" margin-top:0pt ; margin-bottom:0pt; font-family:Times New Roman; font-size:10pt">provides that a corporation generally has the power to purchase and maintain insurance on behalf of any person
who is or was a director, officer, employee or agent of the corporation (or is or was serving at the request of the corporation as a director, officer, employee or agent of another corporation, partnership, joint venture, trust or other enterprise)
against any liability asserted against such person and incurred by such person in any such capacity, or arising out of such person&#146;s status as such, whether or not the corporation would have the power to indemnify such person against such
liability under Section&nbsp;145 of the DGCL. </P></TD></TR></TABLE> <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">Article Eighth of the Registrant&#146;s Amended and Restated Certificate
of Incorporation (the &#147;certificate of incorporation&#148;) contains provisions providing for limitations of director, but not officer, liabilities for monetary damages for breach of fiduciary duties to the fullest extent permitted under the
DGCL and indemnification of and advancement of expenses to its directors, officers, employees and agents to the fullest extent permitted under the DGCL and further provides that any amendment to or repeal of such Article IX or the adoption of any
provision of the certificate of incorporation inconsistent with Article IX shall not eliminate or reduce the effect of the indemnification or limitation of liability provided in Article IX in respect of any matter occurring, or any action or
proceeding accruing or arising or that, but for Article IX, would accrue or arise, prior to such amendment, repeal or adoption of an inconsistent provision. </P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">Article Eighth of the certificate of incorporation requires indemnification for anyone who is or was a director or officer of the Registrant
(or who (i)&nbsp;is or was serving at the request of the Registrant as a director or officer of another corporation, partnership, joint venture, trust or other enterprise or (ii)&nbsp;was a director or officer of a corporation which was a
predecessor corporation of the Registrant or of another enterprise at the request of such predecessor corporation) to the full extent permitted under the DGCL against expenses (including attorneys&#146; fees), judgments, fines, settlements and other
amounts actually and reasonably incurred in connection with any Proceeding, arising by reason of the fact that such person is or was an agent of the Registrant (collectively, &#147;Expenses&#148;), and the certificate of incorporation permits
indemnification for anyone who is an employee or agent (other than a director and officer) (or who (i)&nbsp;is or was an employee or agent of the Registrant, (ii)&nbsp;is or was serving at the request of the Registrant as an employee or agent of
another corporation, partnership, joint venture, trust or other enterprise, or (iii)&nbsp;was an employee or agent of a corporation which was a predecessor corporation of the Registrant or of another enterprise at the request of such predecessor
corporation) against Expenses; provided, however, that the Registrant shall indemnify any such person seeking indemnification in connection with a Proceeding initiated by such person only if the Proceeding was authorized by the board of directors of
the Registrant. </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">Additionally, directors, officers and employees and agents for whom indemnification is permitted have the right under
Article Eighth to be paid Expenses incurred in defending any such Proceeding in advance of its final disposition upon receipt of an undertaking by or on behalf of the indemnified party to repay such amount, if it is ultimately determined by final
judicial decision from which there is no further right to appeal, that the indemnified party is not entitled to be indemnified as authorized in Article Eighth of the certificate of incorporation. The Registrant has entered into form indemnification
agreements with its directors and certain of its officers. Among other things, and subject to certain limitations, the form indemnification agreements provide for advancement and indemnification, within the bounds of Delaware law, for losses
directors and officers may incur in connection with or arising out of the performance of their duties. </P>
</DIV></Center>


<p style="margin-top:1em; margin-bottom:0em; page-break-before:always">
<HR SIZE="3" style="COLOR:#999999" WIDTH="100%" ALIGN="CENTER">


<Center><DIV STYLE="width:8.5in" align="left">
 <P STYLE="margin-top:0pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">Article Eighth of the certificate of incorporation also provides that the Registrant may
purchase and maintain insurance to protect any person who is or was a director, officer, employee or agent of the Registrant (including to the extent they are or were serving at the request of the Registrant as a director, officer, employee, or
agent of another corporation or of a partnership, joint venture, trust, or other enterprise) against any liability asserted against him or her and incurred by him or her in any such capacity, or arising out of his or her status as such, whether or
not the Registrant would have the power to indemnify such person against such liability under the DGCL. The Registrant accordingly maintains standard director and officer insurance policies which insure its directors and officers against certain
liabilities. </P> <P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">The foregoing summaries are necessarily subject to the complete text of the referenced sections of the DGCL, the certificate
of incorporation and the form indemnification agreements and are qualified in their entirety by reference thereto. </P> <P STYLE="margin-top:18pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><B>Item&nbsp;7. Exemption from
Registration Claimed. </B></P> <P STYLE="margin-top:6pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Not Applicable. </P> <P STYLE="margin-top:18pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><B>Item&nbsp;8.
Exhibits. </B></P> <P STYLE="margin-top:6pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">The following documents are filed as exhibits to this Registration Statement. </P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="100%" BORDER="0" STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" ALIGN="center">


<TR>

<TD></TD>

<TD VALIGN="bottom" WIDTH="7%"></TD>
<TD WIDTH="90%"></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:8pt">
<TD VALIGN="bottom">Exhibit&nbsp;No.</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom">Description of Exhibit</TD></TR>


<TR STYLE="font-size:1pt">
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top" NOWRAP>5.1</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="top"><A HREF="d350911dex51.htm">Opinion of Gennari Aronson, LLP*&nbsp;</A></TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top" NOWRAP>23.1</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="top"><A HREF="d350911dex231.htm">Consent of Marcum LLP, independent registered public accounting firm* </A></TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top" NOWRAP>23.2</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="top"><A HREF="d350911dex51.htm">Consent of Gennari Aronson, LLP (included in Exhibit 5.1)* </A></TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top" NOWRAP>24.1</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="top"><A HREF="#sig">Power of Attorney (included in the signature page to this Registration Statement)* </A></TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top" NOWRAP>99.1</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="top"><A HREF="http://www.sec.gov/Archives/edgar/data/1274792/000119312521126831/d97305ddef14a.htm#toc97305_40">2021 Incentive Award Plan (as set forth on&nbsp;Annex&nbsp;A&nbsp;
in the Company&#146;s Definitive Proxy Statement for the 2021 Annual Meeting of Stockholders, filed on April&nbsp;22, 2021) </A></TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top" NOWRAP>107</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="top"><A HREF="d350911dexfilingfees.htm">Filing Fee Table*&nbsp;</A></TD></TR>
</TABLE> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR style = "page-break-inside:avoid">
<TD WIDTH="4%" VALIGN="top" ALIGN="left">*</TD>
<TD ALIGN="left" VALIGN="top"> <P STYLE=" margin-top:0pt ; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman; " ALIGN="left">Filed herewith. </P></TD></TR></TABLE>
<P STYLE="margin-top:18pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman"><B>Item&nbsp;9. Undertakings. </B></P> <P STYLE="margin-top:6pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">(a) The
undersigned Registrant hereby undertakes: </P> <P STYLE="margin-top:6pt; margin-bottom:0pt; text-indent:9%; font-size:10pt; font-family:Times New Roman">(1) To file, during any period in which offers or sales are being made, a post-effective
amendment to this Registration Statement: </P> <P STYLE="margin-top:6pt; margin-bottom:0pt; text-indent:13%; font-size:10pt; font-family:Times New Roman">(i) To include any prospectus required by Section&nbsp;10(a)(3) of the Securities Act; </P>
<P STYLE="margin-top:6pt; margin-bottom:0pt; text-indent:13%; font-size:10pt; font-family:Times New Roman">(ii) To reflect in the prospectus any facts or events arising after the effective date of the Registration Statement (or the most recent
post-effective amendment thereof) which, individually or in the aggregate, represent a fundamental change in the information set forth in the Registration Statement; and </P>
<P STYLE="margin-top:6pt; margin-bottom:0pt; text-indent:13%; font-size:10pt; font-family:Times New Roman">(iii) To include any material information with respect to the plan of distribution not previously disclosed in the Registration Statement or
any material change to such information in the Registration Statement; </P>
</DIV></Center>


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<HR SIZE="3" style="COLOR:#999999" WIDTH="100%" ALIGN="CENTER">


<Center><DIV STYLE="width:8.5in" align="left">
 <P STYLE="margin-top:0pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman"><I>provided, however</I>, that paragraphs (a)(1)(i) and (a)(1)(ii) of this section do not
apply if the information required to be included in a post-effective amendment by those paragraphs is contained in reports filed with or furnished to the Commission by the Registrant pursuant to Section&nbsp;13 or Section&nbsp;15(d) of the Exchange
Act that are incorporated by reference in the Registration Statement. </P> <P STYLE="margin-top:6pt; margin-bottom:0pt; text-indent:9%; font-size:10pt; font-family:Times New Roman">(2) That, for the purpose of determining any liability under the
Securities Act, each such post-effective amendment shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering
thereof. </P> <P STYLE="margin-top:6pt; margin-bottom:0pt; text-indent:9%; font-size:10pt; font-family:Times New Roman">(3) To remove from registration by means of a post-effective amendment any of the securities being registered which remain unsold
at the termination of the offering. </P> <P STYLE="margin-top:6pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">(b) The Registrant hereby undertakes that, for purposes of determining any liability under the
Securities Act, each filing of the Registrant&#146;s annual report pursuant to Section&nbsp;13(a) or Section&nbsp;15(d) of the Exchange Act (and, where applicable, each filing of an employee benefit plan&#146;s annual report pursuant to section
15(d) of the Securities Exchange Act of 1934) that is incorporated by reference in the Registration Statement shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that
time shall be deemed to be the initial bona fide offering thereof. </P> <P STYLE="margin-top:6pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">(c) Insofar as indemnification for liabilities arising under the
Securities Act may be permitted to directors, officers and controlling persons of the Registrant pursuant to the foregoing provisions, or otherwise, the Registrant has been advised that in the opinion of the Commission such indemnification is
against public policy as expressed in the Securities Act and is, therefore, unenforceable. In the event that a claim for indemnification against such liabilities (other than the payment by the Registrant of expenses incurred or paid by a director,
officer or controlling person of the Registrant in the successful defense of any action, suit or proceeding) is asserted by such director, officer or controlling person in connection with the securities being registered, the Registrant will, unless
in the opinion of its counsel the matter has been settled by controlling precedent, submit to a court of appropriate jurisdiction the question whether such indemnification by it is against public policy as expressed in the Securities Act and will be
governed by the final adjudication of such issue. </P>
</DIV></Center>


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 <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B><A NAME="sig"></A>SIGNATURES </B></P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">Pursuant to the requirements of the Securities Act of 1933, as amended, the Registrant certifies that it has reasonable grounds to believe
that it meets all of the requirements for filing on Form <FONT STYLE="white-space:nowrap">S-8</FONT> and has duly caused this Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Cambridge,
Commonwealth of Massachusetts, on this 30th&nbsp;day of November, 2022. </P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P><DIV ALIGN="right">
<TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="40%" BORDER="0" STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt">


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<TD WIDTH="92%"></TD></TR>


<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top" COLSPAN="3"><B>MERRIMACK PHARMACEUTICALS, INC.</B></TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top">By:</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:1pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman">Gary L. Crocker</P></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top" COLSPAN="3">Name: Gary L. Crocker</TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top" COLSPAN="3">Title: President</TD></TR>
</TABLE></DIV> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>POWER OF ATTORNEY AND SIGNATURES </B></P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">KNOW ALL PERSONS BY THESE PRESENTS, that each individual whose signature appears below constitutes and appoints Gary L. Crocker such
individual&#146;s true and lawful <FONT STYLE="white-space:nowrap"><FONT STYLE="white-space:nowrap">attorney-in-fact</FONT></FONT> and agent with full power of substitution and resubstitution, for such individual and in such individual&#146;s name,
place and stead, in any and all capacities, to sign any and all amendments (including post-effective amendments) to this Registration Statement, and to file the same, with all exhibits thereto and all other documents in connection therewith, with
the Commission, granting unto said <FONT STYLE="white-space:nowrap"><FONT STYLE="white-space:nowrap">attorney-in-fact</FONT></FONT> and agent, full power and authority to do and perform each and every act and thing requisite and necessary to be done
in connection therewith, as fully to all intents and purposes as such individual might or could do in person, hereby ratifying and confirming all that said
<FONT STYLE="white-space:nowrap"><FONT STYLE="white-space:nowrap">attorney-in-fact</FONT></FONT> and agent, or his substitute or substitutes, may lawfully do or cause to be done by virtue hereof. This Power of Attorney may be signed in one or more
counterparts, each of which shall be an original, with the same effect as if the signatures thereto and hereto were upon the same instrument. </P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; text-indent:4%; font-size:10pt; font-family:Times New Roman">Pursuant to the requirements of the Securities Act of 1933, as amended, this Registration Statement has been signed by the following persons
in the capacities and on the dates indicated. </P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="100%" BORDER="0" STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" ALIGN="center">


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<TD WIDTH="35%"></TD>

<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="32%"></TD>

<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="31%"></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:8pt">
<TD VALIGN="bottom" NOWRAP STYLE="border-bottom:1.00pt solid #000000"> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:8pt; font-family:Times New Roman"><B>Signature</B></P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center" STYLE="border-bottom:1.00pt solid #000000"> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>Title</B></P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center" STYLE="border-bottom:1.00pt solid #000000"> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>Date</B></P></TD></TR>


<TR STYLE="font-size:1pt">
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:0pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman">/s/ Gary L. Crocker</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman">Gary L. Crocker</P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="top">President and Chairman of the Board (Principal Executive, Financial and Accounting Officer)</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="top">November 30, 2022</TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:0pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman">/s/ Eric D. Andersen</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman">Eric D. Andersen</P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="top">Director</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman">November 30, 2022 </P></TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:0pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman">/s/ Noah G. Levy</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman">Noah G. Levy</P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="top">Director</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman">November 30, 2022 </P></TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:0pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman">/s/ Ana Radeljevic</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman">Ana Radeljevic</P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="top">Director</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman">November 30, 2022 </P></TD></TR>
</TABLE>
</DIV></Center>

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{"company-data": {"conformed-name": "MERRIMACK PHARMACEUTICALS INC", "cik": "0001274792", "assigned-sic": "2834", "irs-number": "000000000", "state-of-incorporation": "DE", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-268609", "film-number": "221435874"}, "business-address": {"street1": "ONE BROADWAY", "street2": "14TH FLOOR", "city": "CAMBRIDGE", "state": "MA", "zip": "02142", "phone": "617-441-1000"}, "mail-address": {"street1": "ONE BROADWAY", "street2": "14TH FLOOR", "city": "CAMBRIDGE", "state": "MA", "zip": "02142"}}
S-8
As filed with the Securities and Exchange Commission on November 30, 2022
Registration
No. 333-
UNITED STATES
SECURITIES
AND EXCHANGE COMMISSION
WASHINGTON, DC 20549
FORM S-8
REGISTRATION STATEMENT
UNDER
THE
SECURITIES ACT OF 1933
MERRIMACK PHARMACEUTICALS, INC.
(Exact Name of Registrant as Specified in Its Charter)
Delaware
04-3210530
(State or Other Jurisdiction of
Incorporation or Organization)
(I.R.S. Employer
Identification No.)
One Broadway, 14th Floor
Cambridge, MA
02142
(Address of Principal Executive Offices)
(Zip Code)
2021 Incentive Award Plan
(Full Title of the Plan)
Gary L. Crocker
President
Merrimack
Pharmaceuticals, Inc.
One Broadway, 14th Floor
Cambridge, Massachusetts 02142
(Name and Address of Agent for Service)
(617) 720-8616
(Telephone Number, Including Area Code, of Agent for Service)
Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer,
a non-accelerated filer,
a smaller reporting company or an emerging growth company. See the definitions of "large accelerated filer," "accelerated filer," "smaller reporting
company," and "emerging growth company" in
Rule 12b-2 of
the Exchange Act.
Large accelerated filer
☐
Smaller Reporting Company ☒
Accelerated filer
☐
Emerging growth company   ☐
Non-accelerated
filer
☒
If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period
for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act.  ☐
PART I
INFORMATION REQUIRED IN THE SECTION 1O(A) PROSPECTUS
The documents containing the information specified in this Part I will be delivered to the participants holding the equity awards covered by
this registration statement on Form
S-8
(the "Registration Statement") as required by Rule 428(b)(1) of the Securities Act of 1933, as amended (the "Securities Act"). Such documents are not
required to be filed with the Securities and Exchange Commission (the "Commission") as part of this Registration Statement.
The Company will
furnish without charge to each person to whom documents containing the information specified in this Part I will be delivered, upon the written or oral request of such person, a copy of any and all of the documents incorporated by reference in Item
3 of Part II of this Registration Statement, other than exhibits to such documents (unless such exhibits are specifically incorporated by reference to the information that is incorporated) and any other documents required to be delivered pursuant to
Rule 428(b). Those documents are incorporated by reference in the Section 10(a) prospectus. Requests should be directed to: Merrimack Pharmaceuticals, Inc. One Broadway, 14th Floor, Cambridge, Massachusetts 02142
(617) 441-1000.
PART II
INFORMATION REQUIRED IN THE REGISTRATION STATEMENT
Item 3. Incorporation of Documents by Reference.
Merrimack Pharmaceuticals, Inc. (the "Registrant") hereby incorporates by reference into this Registration Statement the following documents
previously filed with the Commission pursuant to the Securities Exchange Act of 1934, as amended (the "Exchange Act"):
•
The Registrant's Annual Report on
Form
10-K
for the fiscal year ended December 31, 2021 filed with the Commission on March 9, 2022, which contains audited consolidated financial statements for the most recent fiscal year for which
such statements have been filed;
•
The Registrant's Quarterly Reports on Form
10-Q
for the fiscal
quarters ended March 31, 2022, June 30, 2022 and September 30, 2022, filed on
May 5, 2022
,
August 
4, 2022
and
November 3, 2022
, respectively;
•
The Registrant's Current Reports on Form
8-K
filed on
November 3,
 2022
and
November 9, 2022
(other than information "furnished" under Items 2.02 or 7.01, or
corresponding information furnished under Item 9.01 or included as an exhibit); and
•
The description of the Registrant's Common Stock on
Form
8-A
filed with the Commission on January 27, 2012 pursuant to Section 12(b) of the Exchange Act, including any amendment or report filed for the purpose of updating such description.
All documents, reports and definitive proxy or information statements filed by the
Registrant on or after the date of this Registration Statement pursuant to Sections 13(a), 13(c), 14 and 15(d) of the Exchange Act (other than Current Reports furnished under Item 2.02 or Item 7.01 of Form
8-K
and exhibits furnished on such form that relate to such items), shall be deemed incorporated by reference in this Registration Statement and to be a part hereof from the date of filing such documents until a post-effective amendment of this
Registration Statement is filed which indicates that all securities being offered hereby have been sold or which deregisters all securities then remaining unsold.
Any statement contained in a document incorporated or deemed to be incorporated by reference herein shall be deemed to be modified or
superseded for purposes of this Registration Statement to the extent that a statement contained herein or in any subsequently filed document that also is deemed to be incorporated by reference herein modifies or supersedes such statement. Any such
statement so modified or superseded shall not be deemed, except as so modified or superseded, to constitute a part of this Registration Statement.
Item 4. Description of Securities.
Not applicable.
Item 5. Interests of Named Experts and Counsel.
None.
Item 6. Indemnification of Directors and
Officers.
Section 102(b)(7) of the General Corporation Law of the State of Delaware (the "DGCL") generally permits a
corporation to provide in its certificate of incorporation that a director or officer of the corporation shall not be personally liable to the corporation or its stockholders for monetary damages for breach of fiduciary duty as a director or
officer, except for liability for (i) with respect to directors and officers, any breach of the director's or officer's duty of loyalty to the corporation or its stockholders, (ii) with respect to directors and officers, acts or
omissions not in good faith or which involve intentional misconduct or a knowing violation of law, (iii) with respect to directors, payments of unlawful dividends or unlawful stock repurchases or redemptions under Section 174 of the DGCL,
(iv) with respect to directors and officers, any transaction from which the director or officer derived an improper personal benefit, or (v) with respect to officers, any action by or in the right of the corporation.
Section 145 of the DGCL provides that a corporation may indemnify any person who is or was a director, officer, employee or agent of the
corporation (or is or was serving at the request of the corporation as a director, officer, employee or agent of another corporation, partnership, joint venture, trust or other enterprise), against expenses (including attorneys' fees),
judgments, fines, and settlement amounts actually and reasonably incurred in connection with specified actions, suits, or proceedings brought by third parties, whether civil, criminal, administrative, or investigative (collectively,
"Proceedings"), if the individuals acted in good faith and in a manner they reasonably believed to be in or not opposed to the best interests of the corporation, and, with respect to any criminal action or proceeding, had no reasonable
cause to believe their conduct was unlawful. A similar standard is applicable in the case of derivative actions and actions brought directly by the corporation, except that indemnification only extends to expenses (including attorneys' fees)
actually and reasonably incurred in connection with the defense or settlement of such actions, and the statute requires court approval before there can be any indemnification of such expenses if the person seeking indemnification has been found
liable to the corporation.
Additionally, among other things, Section 145 of the DGCL generally:
•
requires indemnification against expenses (including attorneys' fees) actually and reasonably incurred by
directors and officers, and permits the same for other employees and agents, to the extent they have been successful, on the merits or otherwise, in defending an action, suit, or proceeding or in defense of any claim, issue or matter therein
(whether brought by a third party or by or on behalf of the corporation);
•
permits a corporation to pay expenses of defense in advance of the final disposition of an action, suit, or
proceeding upon receipt (in the case of a current director or officer) of an undertaking to repay any amounts advanced if it is ultimately determined that the director or officer is not entitled to be indemnified;
•
provides that it is not exclusive of other indemnification and advancement of expenses that may be granted by a
corporation's bylaws, disinterested director vote, stockholder vote, agreement, or otherwise; and
•
provides that a corporation generally has the power to purchase and maintain insurance on behalf of any person
who is or was a director, officer, employee or agent of the corporation (or is or was serving at the request of the corporation as a director, officer, employee or agent of another corporation, partnership, joint venture, trust or other enterprise)
against any liability asserted against such person and incurred by such person in any such capacity, or arising out of such person's status as such, whether or not the corporation would have the power to indemnify such person against such
liability under Section 145 of the DGCL.
Article Eighth of the Registrant's Amended and Restated Certificate
of Incorporation (the "certificate of incorporation") contains provisions providing for limitations of director, but not officer, liabilities for monetary damages for breach of fiduciary duties to the fullest extent permitted under the
DGCL and indemnification of and advancement of expenses to its directors, officers, employees and agents to the fullest extent permitted under the DGCL and further provides that any amendment to or repeal of such Article IX or the adoption of any
provision of the certificate of incorporation inconsistent with Article IX shall not eliminate or reduce the effect of the indemnification or limitation of liability provided in Article IX in respect of any matter occurring, or any action or
proceeding accruing or arising or that, but for Article IX, would accrue or arise, prior to such amendment, repeal or adoption of an inconsistent provision.
Article Eighth of the certificate of incorporation requires indemnification for anyone who is or was a director or officer of the Registrant
(or who (i) is or was serving at the request of the Registrant as a director or officer of another corporation, partnership, joint venture, trust or other enterprise or (ii) was a director or officer of a corporation which was a
predecessor corporation of the Registrant or of another enterprise at the request of such predecessor corporation) to the full extent permitted under the DGCL against expenses (including attorneys' fees), judgments, fines, settlements and other
amounts actually and reasonably incurred in connection with any Proceeding, arising by reason of the fact that such person is or was an agent of the Registrant (collectively, "Expenses"), and the certificate of incorporation permits
indemnification for anyone who is an employee or agent (other than a director and officer) (or who (i) is or was an employee or agent of the Registrant, (ii) is or was serving at the request of the Registrant as an employee or agent of
another corporation, partnership, joint venture, trust or other enterprise, or (iii) was an employee or agent of a corporation which was a predecessor corporation of the Registrant or of another enterprise at the request of such predecessor
corporation) against Expenses; provided, however, that the Registrant shall indemnify any such person seeking indemnification in connection with a Proceeding initiated by such person only if the Proceeding was authorized by the board of directors of
the Registrant.
Additionally, directors, officers and employees and agents for whom indemnification is permitted have the right under
Article Eighth to be paid Expenses incurred in defending any such Proceeding in advance of its final disposition upon receipt of an undertaking by or on behalf of the indemnified party to repay such amount, if it is ultimately determined by final
judicial decision from which there is no further right to appeal, that the indemnified party is not entitled to be indemnified as authorized in Article Eighth of the certificate of incorporation. The Registrant has entered into form indemnification
agreements with its directors and certain of its officers. Among other things, and subject to certain limitations, the form indemnification agreements provide for advancement and indemnification, within the bounds of Delaware law, for losses
directors and officers may incur in connection with or arising out of the performance of their duties.
Article Eighth of the certificate of incorporation also provides that the Registrant may
purchase and maintain insurance to protect any person who is or was a director, officer, employee or agent of the Registrant (including to the extent they are or were serving at the request of the Registrant as a director, officer, employee, or
agent of another corporation or of a partnership, joint venture, trust, or other enterprise) against any liability asserted against him or her and incurred by him or her in any such capacity, or arising out of his or her status as such, whether or
not the Registrant would have the power to indemnify such person against such liability under the DGCL. The Registrant accordingly maintains standard director and officer insurance policies which insure its directors and officers against certain
liabilities.
The foregoing summaries are necessarily subject to the complete text of the referenced sections of the DGCL, the certificate
of incorporation and the form indemnification agreements and are qualified in their entirety by reference thereto.
Item 7. Exemption from
Registration Claimed.
Not Applicable.
Item 8.
Exhibits.
The following documents are filed as exhibits to this Registration Statement.
Exhibit No.
Description of Exhibit
5.1
Opinion of Gennari Aronson, LLP*
23.1
Consent of Marcum LLP, independent registered public accounting firm*
23.2
Consent of Gennari Aronson, LLP (included in Exhibit 5.1)*
24.1
Power of Attorney (included in the signature page to this Registration Statement)*
99.1
2021 Incentive Award Plan (as set forth on Annex A 
in the Company's Definitive Proxy Statement for the 2021 Annual Meeting of Stockholders, filed on April 22, 2021)
107
Filing Fee Table*
*
Filed herewith.
Item 9. Undertakings.
(a) The
undersigned Registrant hereby undertakes:
(1) To file, during any period in which offers or sales are being made, a post-effective
amendment to this Registration Statement:
(i) To include any prospectus required by Section 10(a)(3) of the Securities Act;
(ii) To reflect in the prospectus any facts or events arising after the effective date of the Registration Statement (or the most recent
post-effective amendment thereof) which, individually or in the aggregate, represent a fundamental change in the information set forth in the Registration Statement; and
(iii) To include any material information with respect to the plan of distribution not previously disclosed in the Registration Statement or
any material change to such information in the Registration Statement;
provided, however
, that paragraphs (a)(1)(i) and (a)(1)(ii) of this section do not
apply if the information required to be included in a post-effective amendment by those paragraphs is contained in reports filed with or furnished to the Commission by the Registrant pursuant to Section 13 or Section 15(d) of the Exchange
Act that are incorporated by reference in the Registration Statement.
(2) That, for the purpose of determining any liability under the
Securities Act, each such post-effective amendment shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering
thereof.
(3) To remove from registration by means of a post-effective amendment any of the securities being registered which remain unsold
at the termination of the offering.
(b) The Registrant hereby undertakes that, for purposes of determining any liability under the
Securities Act, each filing of the Registrant's annual report pursuant to Section 13(a) or Section 15(d) of the Exchange Act (and, where applicable, each filing of an employee benefit plan's annual report pursuant to section
15(d) of the Securities Exchange Act of 1934) that is incorporated by reference in the Registration Statement shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that
time shall be deemed to be the initial bona fide offering thereof.
(c) Insofar as indemnification for liabilities arising under the
Securities Act may be permitted to directors, officers and controlling persons of the Registrant pursuant to the foregoing provisions, or otherwise, the Registrant has been advised that in the opinion of the Commission such indemnification is
against public policy as expressed in the Securities Act and is, therefore, unenforceable. In the event that a claim for indemnification against such liabilities (other than the payment by the Registrant of expenses incurred or paid by a director,
officer or controlling person of the Registrant in the successful defense of any action, suit or proceeding) is asserted by such director, officer or controlling person in connection with the securities being registered, the Registrant will, unless
in the opinion of its counsel the matter has been settled by controlling precedent, submit to a court of appropriate jurisdiction the question whether such indemnification by it is against public policy as expressed in the Securities Act and will be
governed by the final adjudication of such issue.
SIGNATURES
Pursuant to the requirements of the Securities Act of 1933, as amended, the Registrant certifies that it has reasonable grounds to believe
that it meets all of the requirements for filing on Form
S-8
and has duly caused this Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Cambridge,
Commonwealth of Massachusetts, on this 30th day of November, 2022.
MERRIMACK PHARMACEUTICALS, INC.
By:
Gary L. Crocker
Name: Gary L. Crocker
Title: President
POWER OF ATTORNEY AND SIGNATURES
KNOW ALL PERSONS BY THESE PRESENTS, that each individual whose signature appears below constitutes and appoints Gary L. Crocker such
individual's true and lawful
attorney-in-fact
and agent with full power of substitution and resubstitution, for such individual and in such individual's name,
place and stead, in any and all capacities, to sign any and all amendments (including post-effective amendments) to this Registration Statement, and to file the same, with all exhibits thereto and all other documents in connection therewith, with
the Commission, granting unto said
attorney-in-fact
and agent, full power and authority to do and perform each and every act and thing requisite and necessary to be done
in connection therewith, as fully to all intents and purposes as such individual might or could do in person, hereby ratifying and confirming all that said
attorney-in-fact
and agent, or his substitute or substitutes, may lawfully do or cause to be done by virtue hereof. This Power of Attorney may be signed in one or more
counterparts, each of which shall be an original, with the same effect as if the signatures thereto and hereto were upon the same instrument.
Pursuant to the requirements of the Securities Act of 1933, as amended, this Registration Statement has been signed by the following persons
in the capacities and on the dates indicated.
Signature
Title
Date
/s/ Gary L. Crocker
Gary L. Crocker
President and Chairman of the Board (Principal Executive, Financial and Accounting Officer)
November 30, 2022
/s/ Eric D. Andersen
Eric D. Andersen
Director
November 30, 2022
/s/ Noah G. Levy
Noah G. Levy
Director
November 30, 2022
/s/ Ana Radeljevic
Ana Radeljevic
Director
November 30, 2022