0000950170-24-060478 | 10-Q | XBRL Viewer | Merrimack Pharmaceuticals INC

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Net Income (Loss) Per Common Share - Schedule of Outstanding Options Excluded from Computation of Diluted Loss Per Share (Detail) - shares shares in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Outstanding Options to Purchase Common Stock [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Outstanding options to purchase common stock	344	695

Summary of Significant Accounting Policies	3 Months Ended
Summary of Significant Accounting Policies	Mar. 31, 2024
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation The accompanying condensed consolidated financial statements reflect the operations of Merrimack Pharmaceuticals, Inc. and its wholly owned subsidiaries. All intercompany accounts and transactions have been eliminated. The condensed consolidated financial statements are unaudited and have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”). The accounting policies followed in the preparation of the interim condensed consolidated financial statements are consistent in all material respects with those presented in Note 1 to the financial statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2023. Unaudited Interim Financial Information The condensed consolidated balance sheet as of December 31, 2023 was derived from audited financial statements for the year ended December 31, 2023, but does not include all disclosures required by GAAP. The condensed consolidated balance sheet as of March 31, 2024, the condensed consolidated statements of operations and comprehensive loss for the three months ended March 31, 2024 and 2023, the condensed consolidated statements of stockholders’ equity for the three months ended March 31, 2024 and 2023 and the condensed consolidated statements of cash flows for the three months ended March 31, 2024 and 2023 are unaudited. The unaudited interim condensed consolidated financial statements have been prepared on the same basis as the audited annual financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for the fair statement of the Company’s financial position as of March 31, 2024, the results of its operations for the three months ended March 31, 2024 and 2023, its statements of stockholders’ equity for the three months ended March 31, 2024 and 2023 and its statements of cash flows for the three months ended March 31, 2024 and 2023. The financial data and other information disclosed in the notes related to the three months ended March 31, 2024 and 2023 are unaudited. The results for the three months ended March 31, 2024 and 2023 are not necessarily indicative of results to be expected for the year ending December 31, 2024, any other interim periods, or any future year or period. The unaudited interim financial statements of the Company included herein have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”). Certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted from this report, as is permitted by such rules and regulations. These unaudited condensed consolidated financial statements should be read in conjunction with the audited financial statements and the notes thereto contained in the Company’s Annual Report on Form 10-K for the year ended December 31, 2023 filed with the SEC on March 7, 2024. Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates, assumptions and judgments that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements and the reported amounts of expenses during the reporting periods. Significant estimates, assumptions and judgments reflected in these condensed consolidated financial statements include, but are not limited to, the accrual of research and development expenses and the valuation of stock-based awards. Estimates are periodically reviewed in light of changes in circumstances, facts and experience. Actual results could differ from the Company’s estimates.

Discontinued Operations - Sale of Commercial Business

3 Months Ended

Mar. 31, 2024

Discontinued Operations and Disposal Groups [Abstract]

Discontinued Operations - Sale of Commercial Business

3. Discontinued Operations - Sale of Commercial Business

Ipsen

On April 3, 2017, the Company completed the sale of the Commercial Business to Ipsen. The Commercial Business represented a discontinued operation since the disposal of the Commercial Business was a strategic shift that had a major effect on the Company’s operations and financial results. The Company will not have further significant involvement in the operations of the discontinued Commercial Business. The operating results of the Commercial Business are reported as discontinued operations, net of tax in the condensed consolidated statements of operations and comprehensive loss for all periods presented.

Discontinued Operations

The condensed consolidated financial statements for the three months ended March 31, 2024 and 2023 reflect the operations of the Commercial Business as a discontinued operation. Discontinued operations for the three months ended March 31, 2024 and 2023 includes the following:


	Three Months Ended March 31,
(in thousands)	2024			2023
Other income and expenses:
Gain on sale of Commercial Business	$	225,000		$	—
Income from discontinued operations		225,000			—
Income tax expense		(23,194	)		—
Total income from discontinued operations	$	201,806		$	—

During the three months ended March 31, 2024, the Company received $225.0 million milestone payment related to the development and commercialization of ONIVYDE. The Company included the $225.0 million in discontinued operations because the amounts directly relate to the Commercial Business, which was classified as a discontinued operation.

The Company recorded the income tax implications of the milestone payment in the first quarter of 2024 on a discrete basis. The milestone generated taxable income for the Company which has resulted in income tax expense. The Company released a portion of its valuation allowance in the three months ended March 31, 2024 as it is now able to utilize its net operating loss carryforwards to offset the taxable income generated from the milestone payment. The Company’s current income tax expense for the three months ended March 31, 2024 is $23.2 million, which is comprised primarily of federal IRC Section 453A interest and the Massachusetts equivalent of IRC Section 453A interest expense.

Fair Value of Financial Instruments - Summary of Carrying Values and Fair Values of Financial Instruments (Detail) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Schedule of Held-to-Maturity Securities [Line Items]
Short-term investments, Amortized Cost	$ 9,950	$ 12,886
Short-term investments, Net Carrying Amount	9,950	12,886
Short-term investments, Fair Value	9,950	12,886
Treasury Bills and Notes [Member]
Schedule of Held-to-Maturity Securities [Line Items]
Short-term investments, Amortized Cost	9,950	12,886
Short-term investments, Net Carrying Amount	9,950	12,886
Short-term investments, Fair Value	$ 9,950	$ 12,886

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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+ Details

Net Income (Loss) Per Common Share

3 Months Ended

Mar. 31, 2024

Earnings Per Share [Abstract]

Net Income (Loss) Per Common Share

7. Net Income (Loss) Per Common Share

Basic net income (loss) per share is calculated by dividing the net loss attributable to Merrimack Pharmaceuticals, Inc. by the weighted-average number of common shares outstanding during the period.

Diluted net income (loss) per share is computed by dividing the net income (loss) attributable to Merrimack Pharmaceuticals, Inc. by the weighted-average number of dilutive common shares outstanding during the period. Dilutive shares outstanding is calculated by adding to the weighted shares outstanding any potential (unissued) shares of common stock from outstanding stock options based on the treasury stock method. Outstanding stock options were not included in the diluted net income (loss) per share calculation because in a period when a net loss from continuing operations is reported, all common stock equivalents are excluded from the calculation because they would have an anti-dilutive effect, meaning the income (loss) per share would be reduced. Therefore, in periods where a net loss from continuing operations is reported, there is no difference in basic and dilutive income (loss) per share.

Stock options are excluded from the calculation of diluted income (loss) per share because the net income (loss) for the three months ended March 31, 2024 and 2023 causes such securities to be anti-dilutive. Outstanding options excluded from the calculation of diluted income (loss) per share for the three months ended March 31, 2024 and 2023 are shown in the chart below:


	Three Months Ended March 31,
(in thousands)	2024		2023
Outstanding options to purchase common stock		344		695

Recent Accounting Pronouncements	3 Months Ended
Mar. 31, 2024
Accounting Changes And Error Corrections [Abstract]
Recent Accounting Pronouncements	8. Recent Accounting Pronouncements From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (“FASB”) or other standard setting bodies that the Company adopts as of the specified effective date. Unless otherwise discussed above, the Company does not believe that the adoption of recently issued standards has or may have a material impact on the Company’s condensed consolidated financial statements or disclosures.

Recent Accounting Pronouncements

3 Months Ended

Mar. 31, 2024

Accounting Changes And Error Corrections [Abstract]

Recent Accounting Pronouncements

8. Recent Accounting Pronouncements

From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (“FASB”) or other standard setting bodies that the Company adopts as of the specified effective date. Unless otherwise discussed above, the Company does not believe that the adoption of recently issued standards has or may have a material impact on the Company’s condensed consolidated financial statements or disclosures.

- Definition

The entire disclosure for change in accounting principle. Includes, but is not limited to, nature, reason, and method of adopting amendment to accounting standards or other change in accounting principle.

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+ Details

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Cash flows from operating activities
Net income (loss)	$ 201,370	$ (271)
Income from discontinued operations	(201,806)
Loss from continuing operations	(436)	(271)
Adjustments to reconcile net loss to net cash used in operating activities
Gain on sale of in-process research and development		(139)
Accretion of interest income	(64)
Stock-based compensation expense	48	17
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	100	162
Accounts payable, accrued expenses and other	125	(126)
Other assets	1	1
Net cash used in continuing operations for operating activities	(226)	(356)
Net cash used in discontinued operations for operating activities	(1,088)
Net cash used in operating activities	(1,314)	(356)
Cash flows from investing activities
Proceeds from milestone of a discontinued operation	225,000
Net proceeds from sale of in-process research and development		139
Proceeds from maturity of short-term investments	3,000
Net cash provided by investing activities	228,000	139
Cash flows from financing activities
Proceeds from exercise of stock options	1,485	179
Net cash provided by financing activities	1,485	179
Net increase (decrease) in cash and cash equivalents	228,171	(38)
Cash and cash equivalents, beginning of period	5,989	19,439
Cash and cash equivalents, end of period	234,160	$ 19,401
Supplemental disclosure of cash flows
Cash paid for income taxes	$ 1,088

Subsequent Events

3 Months Ended

Mar. 31, 2024

Subsequent Events [Abstract]

Subsequent Events

9. Subsequent Events

On May 10, 2024, the Company’s stockholders approved a Plan of Dissolution whereby the Company will cease operations and dissolve in accordance with Delaware law. Stockholders of record on May 10, 2024 will receive a one-time liquidating dividend of $15.10 per share, which dividend is expected to be paid on or around May 17. Thereafter, the Company intends to transfer any remaining rights to any potential future milestone payments, as described below, from Ipsen Pharmaceuticals or Elevation Oncology to a liquidating trust. Currently, the Company has no expectation that any future milestone payments will occur. If any future milestone payments were received, they would be distributed to stockholders of record as of May 10, 2024. Following the stockholders’ meeting, the Company expects to delist from trading on NASDAQ on or around May 15, 2024 and to terminate its registration as a reporting company under the Securities Exchange Act of 1934, as amended.

Fair Value of Financial Instruments

3 Months Ended

Mar. 31, 2024

Fair Value Disclosures [Abstract]

Fair Value of Financial Instruments

4. Fair Value of Financial Instruments

The following tables show assets measured at fair value on a recurring basis as of March 31, 2024 and December 31, 2023:


	March 31, 2024
(in thousands)	Level 1		Level 2		Level 3
Cash equivalents:
Money market funds	$	5,996	$	—	$	—
Totals	$	5,996	$	—	$	—

Short-term investments:
Treasury bills and notes	$	—	$	9,950	$	—
Totals	$	—	$	9,950	$	—


	December 31, 2023
(in thousands)	Level 1		Level 2		Level 3
Cash equivalents:
Money market funds	$	5,721	$	—	$	—
Totals	$	5,721	$	—	$	—

Short-term investments:
Treasury bills and notes	$	—	$	12,886	$	—
Totals	$	—	$	12,886	$	—

There were no liabilities measured at fair value on a recurring basis as of March 31, 2024 and December 31, 2023.

The following table summarizes the carrying values and fair values of the Company's financial instruments:


	March 31, 2024
(in thousands)	Amortized Cost		Allowance for Credit Losses		Net Carrying Amount		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Short-term investments:
Treasury bills and notes	$	9,950	$	—	$	9,950	$	—	$	—	$	9,950
Total short-term investments	$	9,950	$	—	$	9,950	$	—	$	—	$	9,950


	December 31, 2023
(in thousands)	Amortized Cost		Allowance for Credit Losses		Net Carrying Amount		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Short-term investments:
Treasury bills and notes	$	12,886	$	—	$	12,886	$	—	$	—	$	12,886
Total short-term investments	$	12,886	$	—	$	12,886	$	—	$	—	$	12,886

The Company has investments in U.S. Treasury Bills and U.S. Treasury Notes as of March 31, 2024 and December 31, 2023, some of which mature over a period greater than 90 days but within one year and are classified as short-term investments. The U.S. Treasury Bills and U.S. Treasury Notes are carried at amortized cost and classified as held to maturity as the Company has the intent and the ability to hold them until they mature. The carrying value of the U.S. Treasury Bills and U.S. Treasury Notes are adjusted for accretion of discounts over the remaining life of the investment. Income related to the U.S. Treasury Bills and U.S. Treasury Notes is recognized in interest income in the Company’s consolidated statement of operations and comprehensive loss.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Fair Value of Financial Instruments - Additional Information (Detail) - USD ($)	Mar. 31, 2024	Dec. 31, 2023
Recurring Basis [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Liabilities measured at fair value	$ 0	$ 0

Discontinued Operations - Sale of Commercial Business - Summary of Discontinued Operations (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2024 USD ($)
Other income and expenses:
Gain on sale of Commercial Business	$ 225,000
Income from discontinued operations	225,000
Income tax expense	(23,194)
Total income from discontinued operations	$ 201,806

- Definition

Amount before tax of income (loss) from a discontinued operation. Includes, but is not limited to, the income (loss) from operations during the phase-out period, gain (loss) on disposal, gain (loss) for reversal of write-down (write-down) to fair value, less cost to sell, and adjustments to a prior period gain (loss) on disposal.

+ References + Details

- Definition

Amount of tax expense (benefit) related to a discontinued operation. Includes, but is not limited to, tax expense (benefit) related to income (loss) from operations during the phase-out period, tax expense (benefit) related to gain (loss) on disposal, tax expense (benefit) related to gain (loss) for reversal of write-down (write-down) to fair value, less cost to sell, and tax expense (benefit) related to adjustments of a prior period gain (loss) on disposal.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 10
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482685/740-10-50-10

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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-Subparagraph (b)
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
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+ Details

- Definition

Amount after tax of income (loss) from a discontinued operation attributable to the parent. Includes, but is not limited to, the income (loss) from operations during the phase-out period, gain (loss) on disposal, gain (loss) for reversal of write-down (write-down) to fair value, less cost to sell, and adjustments to a prior period gain (loss) on disposal.

+ References + Details

Stock-Based Compensation

3 Months Ended

Mar. 31, 2024

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock-Based Compensation

6. Stock-Based Compensation

On April 15, 2021, the Company’s Board of Directors adopted the 2021 Incentive Award Plan (the “2021 Plan”) to replace the 2011 Stock Incentive Plan (the “2011 Plan”). The 2021 Plan was approved by the Company’s stockholders at the Company’s Annual Meeting of Stockholders held on June 10, 2021. The 2021 Plan is administered by the Company’s Board of Directors and permits the Company to grant incentive and non-qualified stock options, stock appreciation rights, restricted stock, restricted stock units and other stock-based awards.

The Company initially reserved 275,000 of its common stock for the issuance of awards under the 2021 Plan. There were no options granted during each of the three months ended March 31, 2024 and 2023 under the 2021 Plan. At March 31, 2024, there were 209,000 shares remaining available for grant under the 2021 Plan.

The aggregate intrinsic value was calculated as the difference between the exercise price of the stock options and the fair value of the underlying common stock. The aggregate intrinsic value of options exercised during the three months ended March 31, 2024 and 2023 is $1.1 million and $0.3 million, respectively.

The Company recognized stock-based compensation expense of $48 thousand and $17 thousand in general and administrative expenses during the three months ended March 31, 2024 and 2023, respectively.

Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Operating expenses:
General and administrative expenses	$ 669	$ 586
Gain on sale of in-process research and development		(139)
Total operating expenses	669	447
Loss from operations	(669)	(447)
Other income:
Interest income	233	176
Total other income	233	176
Net loss from continuing operations	(436)	(271)
Discontinued operations:
Income from discontinued operations, net of tax	201,806
Net income and comprehensive income	$ 201,370	$ (271)
Basic and dilutive net income (loss) per common share
Net loss from continuing operations - basic	$ (0.03)	$ (0.02)
Net loss from continuing operations - diluted	(0.03)	(0.02)
Net income from discontinued operations, net of tax - basic	13.96
Net income from discontinued operations, net of tax - diluted	13.96
Net income (loss) per common share - basic	13.93	(0.02)
Net income (loss) per common share - diluted	$ 13.93	$ (0.02)
Weighted-average common shares used to compute basic net income (loss) per common share	14,452	14,252
Weighted-average common shares used to compute diluted net income (loss) per common share	14,452	14,252

Fair Value of Financial Instruments - Summary of Assets Measured at Fair Value on a Recurring Basis (Detail) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term investments	$ 9,950	$ 12,886
Recurring Basis [Member] \| Level 1 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	5,996	5,721
Recurring Basis [Member] \| Level 1 [Member] \| Money Market Funds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	5,996	5,721
Recurring Basis [Member] \| Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term investments	9,950	12,886
Recurring Basis [Member] \| Level 2 [Member] \| Treasury Bills and Notes [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term investments	$ 9,950	$ 12,886

Nature of the Business - Additional Information (Detail) - USD ($)			1 Months Ended	3 Months Ended
	Feb. 13, 2024	Jan. 23, 2023	Jul. 12, 2019	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Apr. 03, 2017
Summary Of Significant Accounting Policies [Line Items]
Accumulated deficit				$ 347,447,000		$ 548,817,000
Net loss from continuing operations				(436,000)	$ (271,000)
Cash used in operating activities				1,314,000	$ 356,000
Cash and cash equivalents and short-term investments				$ 244,100,000
Asset Purchase Option Agreement [Member]
Summary Of Significant Accounting Policies [Line Items]
Gain related to option fee payment		$ 100,000
Terms of exercise option		The Purchaser decided not to exercise the Option in July 2023
Asset Purchase Option Agreement [Member] \| Pegascy SAS [Member]
Summary Of Significant Accounting Policies [Line Items]
Consideration receivable		$ 700,000
Option fee		200,000
Asset Purchase Option Agreement [Member] \| Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Transaction expenses		$ 100,000
Ipsen [Member]
Summary Of Significant Accounting Policies [Line Items]
Additional contingent milestone payments	$ 225,000,000
Ipsen [Member] \| Asset Sale Agreement [Member] \| Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Contingent milestone payments receivable							$ 225,000,000.0
Ipsen [Member] \| First Line Treatment of Metastatic Adenocarcinoma of Pancreas [Member]
Summary Of Significant Accounting Policies [Line Items]
Contingent milestone payments received	225,000,000
Ipsen [Member] \| First Line Treatment Of Metastatic Pancreatic Ductal Adenocarcinoma [Member]
Summary Of Significant Accounting Policies [Line Items]
Contingent milestone payments received	$ 225,000,000
Ipsen [Member] \| After Failure of First Line Chemotherapy [Member]
Summary Of Significant Accounting Policies [Line Items]
Contingent milestone payments receivable							150,000,000
Ipsen [Member] \| Additional Indication [Member]
Summary Of Significant Accounting Policies [Line Items]
Contingent milestone payments receivable							$ 75,000,000
14ner Sale [Member]
Summary Of Significant Accounting Policies [Line Items]
Upfront cash payment received			$ 3,500,000
14ner Sale [Member] \| Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Additional payments receivable on achievement of certain milestone events			54,500,000
14ner Sale [Member] \| Achievement of the Primary Endpoint in the First Registrational Clinical Study of Either MM-121 or MM-111 [Member] \| Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Additional payments receivable on achievement of certain milestone events			3,000,000.0
14ner Sale [Member] \| Achievement of Various Regulatory Approval and Reimbursement-Based Milestones in the United States, Europe and Japan [Member] \| Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Additional payments receivable on achievement of certain milestone events			16,500,000
14ner Sale [Member] \| Achievement Various Cumulative Worldwide Net Sales Targets Between $100.0 million and $300.0 million for MM-121 and MM-111 [Member] \| Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Additional payments receivable on achievement of certain milestone events			35,000,000.0
Cumulative worldwide net sales target			$ 300,000,000.0

Accounts Payable, Accrued Expenses and Other

3 Months Ended

Mar. 31, 2024

Payables And Accruals [Abstract]

Accounts Payable, Accrued Expenses and Other

5. Accounts Payable, Accrued Expenses and Other

Accounts payable, accrued expenses and other as of March 31, 2024 and December 31, 2023 consisted of the following:


(in thousands)	March 31, 2024		December 31, 2023
Accounts payable	$	168	$	74
Accrued goods and services		161		130
Accrued clinical trial costs		46		46
Others		191		191
Total accounts payable, accrued expenses and other	$	566	$	441

Accounts Payable, Accrued Expenses and Other (Tables)

3 Months Ended

Mar. 31, 2024

Payables And Accruals [Abstract]

Schedule of Accounts Payable, Accrued Expenses and Other

Accounts payable, accrued expenses and other as of March 31, 2024 and December 31, 2023 consisted of the following:


(in thousands)	March 31, 2024		December 31, 2023
Accounts payable	$	168	$	74
Accrued goods and services		161		130
Accrued clinical trial costs		46		46
Others		191		191
Total accounts payable, accrued expenses and other	$	566	$	441

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Current assets:
Cash and cash equivalents	$ 234,160	$ 5,989
Short-term investments	9,950	12,886
Prepaid expenses and other current assets	209	309
Total current assets	244,319	19,184
Other assets	3	4
Total assets	244,322	19,188
Current liabilities:
Accounts payable, accrued expenses and other	566	441
Income taxes payable	22,106
Total current liabilities	22,672	441
Total liabilities	22,672	441
Commitments and contingencies
Stockholders’ equity:
Preferred stock, $0.01 par value: 10,000 shares authorized at March 31, 2024 and December 31, 2023; no shares issued or outstanding at March 31, 2024 or December 31, 2023
Common stock, $0.01 par value: 30,000 shares authorized at March 31, 2024 and December 31, 2023; 14,532 and 14,351 shares issued and outstanding at March 31, 2024 and December 31, 2023, respectively	1,345	1,343
Additional paid-in capital	567,752	566,221
Accumulated deficit	(347,447)	(548,817)
Total stockholders’ equity	221,650	18,747
Total liabilities and stockholders’ equity	$ 244,322	$ 19,188

Net Income (Loss) Per Common Share (Tables)

3 Months Ended

Mar. 31, 2024

Earnings Per Share [Abstract]

Schedule of Outstanding Options Excluded from Computation of Diluted Loss Per Share

Outstanding options excluded from the calculation of diluted income (loss) per share for the three months ended March 31, 2024 and 2023 are shown in the chart below:


	Three Months Ended March 31,
(in thousands)	2024		2023
Outstanding options to purchase common stock		344		695

Condensed Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Deficit [Member]
Balance at Dec. 31, 2022	$ 19,247	$ 1,342	$ 565,541	$ (547,636)
Balance (in shares) at Dec. 31, 2022		14,215
Exercise of stock options	179	$ 1	178
Exercise of stock options (in shares)		40
Stock-based compensation	17		17
Net loss	(271)			(271)
Balance at Mar. 31, 2023	19,172	$ 1,343	565,736	(547,907)
Balance (in shares) at Mar. 31, 2023		14,255
Balance at Dec. 31, 2023	18,747	$ 1,343	566,221	(548,817)
Balance (in shares) at Dec. 31, 2023		14,351
Exercise of stock options	1,485	$ 2	1,483
Exercise of stock options (in shares)		181
Stock-based compensation	48		48
Net loss	201,370			201,370
Balance at Mar. 31, 2024	$ 221,650	$ 1,345	$ 567,752	$ (347,447)
Balance (in shares) at Mar. 31, 2024		14,532

- Definition

The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
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- Definition

Amount of equity (deficit) attributable to parent. Excludes temporary equity and equity attributable to noncontrolling interest.

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+ Details

Document and Entity Information - shares	3 Months Ended
Document and Entity Information - shares	Mar. 31, 2024	May 13, 2024
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2024
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q1
Trading Symbol	MACK
Entity Registrant Name	MERRIMACK PHARMACEUTICALS INC
Entity Central Index Key	0001274792
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		14,788,369
Entity Interactive Data Current	Yes
Title of 12(b) Security	Common stock, $0.01 par value
Security Exchange Name	NASDAQ
Entity File Number	001-35409
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	04-3210530
Entity Address, Address Line One	One Broadway
Entity Address, Address Line Two	14th Floor
Entity Address, City or Town	Cambridge
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02142
City Area Code	617
Local Phone Number	720-8606
Document Quarterly Report	true
Document Transition Report	false

Stock-Based Compensation - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate intrinsic value of options exercised	$ 1,100	$ 300
General and Administrative Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share Based Compensation Expense	$ 48	$ 17
Stock Incentive Plan 2021 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock for the issuance			275,000
Number of Options, Granted	0	0
Shares of common stock available for grant (in shares)	209,000

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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+ Details

Fair Value of Financial Instruments (Tables)

3 Months Ended

Mar. 31, 2024

Fair Value Disclosures [Abstract]

Summary of Assets Measured at Fair Value on a Recurring Basis

The following tables show assets measured at fair value on a recurring basis as of March 31, 2024 and December 31, 2023:


	March 31, 2024
(in thousands)	Level 1		Level 2		Level 3
Cash equivalents:
Money market funds	$	5,996	$	—	$	—
Totals	$	5,996	$	—	$	—

Short-term investments:
Treasury bills and notes	$	—	$	9,950	$	—
Totals	$	—	$	9,950	$	—


	December 31, 2023
(in thousands)	Level 1		Level 2		Level 3
Cash equivalents:
Money market funds	$	5,721	$	—	$	—
Totals	$	5,721	$	—	$	—

Short-term investments:
Treasury bills and notes	$	—	$	12,886	$	—
Totals	$	—	$	12,886	$	—

Summary of Carrying Values and Fair Values of Financial Instruments

The following table summarizes the carrying values and fair values of the Company's financial instruments:


	March 31, 2024
(in thousands)	Amortized Cost		Allowance for Credit Losses		Net Carrying Amount		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Short-term investments:
Treasury bills and notes	$	9,950	$	—	$	9,950	$	—	$	—	$	9,950
Total short-term investments	$	9,950	$	—	$	9,950	$	—	$	—	$	9,950


	December 31, 2023
(in thousands)	Amortized Cost		Allowance for Credit Losses		Net Carrying Amount		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Short-term investments:
Treasury bills and notes	$	12,886	$	—	$	12,886	$	—	$	—	$	12,886
Total short-term investments	$	12,886	$	—	$	12,886	$	—	$	—	$	12,886

- Definition

Tabular disclosure of information about investment in debt security measured at amortized cost (held-to-maturity).

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+ Details

Discontinued Operations - Sale of Commercial Business - Additional Information (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2024 USD ($)
Discontinued Operations and Disposal Groups [Abstract]
Development and commercialization milestone payment received	$ 225,000
Discontinued operations directly relate to Commercial Business	225,000
Income tax expense	$ 23,194

- Definition

+ References

+ Details

Accounts Payable, Accrued Expenses and Other - Schedule of Accounts Payable, Accrued Expenses and Other (Detail) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Payables And Accruals [Abstract]
Accounts payable	$ 168	$ 74
Accrued goods and services	161	130
Accrued clinical trial costs	46	46
Others	191	191
Total accounts payable, accrued expenses and other	$ 566	$ 441

Discontinued Operations - Sale of Commercial Business (Tables)

3 Months Ended

Mar. 31, 2024

Discontinued Operations and Disposal Groups [Abstract]

Summary of Discontinued Operations

Discontinued operations for the three months ended March 31, 2024 and 2023 includes the following:


	Three Months Ended March 31,
(in thousands)	2024			2023
Other income and expenses:
Gain on sale of Commercial Business	$	225,000		$	—
Income from discontinued operations		225,000			—
Income tax expense		(23,194	)		—
Total income from discontinued operations	$	201,806		$	—

- Definition

Tabular disclosure of information related to a disposal group. Includes, but is not limited to, a discontinued operation, disposal classified as held-for-sale or disposed of by means other than sale or disposal of an individually significant component.

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+ Details

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2024	Dec. 31, 2023
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	30,000,000	30,000,000
Common stock, shares issued	14,532,000	14,351,000
Common stock, shares outstanding	14,532,000	14,351,000

Nature of the Business

3 Months Ended

Mar. 31, 2024

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Nature of the Business

1. Nature of the Business

Merrimack Pharmaceuticals, Inc. (the “Company”) is a biopharmaceutical company based in Cambridge, Massachusetts that is entitled to receive up to $225.0 million in contingent milestone payments related to its sale of ONIVYDE® and MM-436 (the “Commercial Business”) to Ipsen S.A. (“Ipsen”) in April 2017 (the “Ipsen Sale”). The Company does not have any ongoing research or development activities. The Company does not have any employees and instead uses external consultants for the operation of the Company.

On February 13, 2024, the Company announced that Ipsen S.A. announced it had received approval from the U.S. Food and Drug Administration (“FDA”) to market ONIVYDE as a first-line treatment of metastatic adenocarcinoma on the pancreas. As a result of this approval by the FDA, the Company received a $225 million milestone payment from Ipsen under the terms of the Ipsen Sale in March 2024. On May 10, 2024, the Company’s stockholders approved a plan of dissolution (the “Plan of Dissolution”) whereby the Company will cease operations and dissolve in accordance with Delaware law. Stockholders of record on May 10, 2024 will receive a one-time liquidating dividend of $15.10 per share, which dividend is expected to be paid on or around May 17. Thereafter, the Company intends to transfer any remaining rights to any potential future milestone payments, as described below, from Ipsen Pharmaceuticals or Elevation Oncology to a liquidating trust. Currently, the Company has no expectation that any future milestone payments will occur. If any future milestone payments were received, they would be distributed to stockholders of record as of May 10, 2024. Following the stockholders’ meeting, the Company expects to delist from trading on NASDAQ on or around May 15, 2024 and to terminate its registration as a reporting company under the Securities Exchange Act of 1934, as amended.

In addition to the $225 million milestone that the Company received in March 2024, based upon the approval announced by the FDA on February 13, 2024 of ONIVYDE® for the first-line treatment of metastatic pancreatic ductal adenocarcinoma (“mPDAC”), there are $225 million of additional contingent milestone payments which could result from the Ipsen Sale. The Company believes that the probability of receiving these additional milestones is remote based on publicly available information provided by Ipsen. The $225.0 million in contingent milestone payments resulting from the Ipsen Sale consist of:

•

$150.0 million upon approval by the FDA of ONIVYDE® for the treatment of small-cell lung cancer after failure of first-line chemotherapy; and

•

$75.0 million upon approval by the FDA of ONIVYDE® for an additional indication unrelated to those described above.

On May 30, 2019, the Company announced the completion of its review of strategic alternatives, following which the Company’s board of directors (the “Board”) implemented a series of measures designed to extend the Company’s cash runway and preserve its ability to capture the potential milestone payments resulting from the Ipsen Sale. In connection with that announcement, the Company discontinued the discovery efforts on its remaining preclinical programs: MM-401, an agonistic antibody targeting a novel immuno-oncology target, TNFR2; and MM-201, a highly stabilized agonist-Fc fusion protein targeting death receptors 4 and 5.

The Company’s termination of its executive management team and all other employees was substantially completed by June 28, 2019 and fully completed by July 12, 2019. As of July 12, 2019, the Company no longer had any employees. The Company has engaged external consultants to run the day-to-day operations of the Company. The Company has also entered into consulting agreements with certain former members of its executive management team who are supporting the Company’s relationship with current partners, and assisting with certain legal and regulatory matters and the continued wind-down of operations.

On July 12, 2019, the Company completed the sale to Elevation Oncology, Inc. (formerly known as 14ner Oncology, Inc.) (“Elevation”) of its anti-HER3 antibody programs, MM-121 (seribantumab) and MM-111 (the “Elevation Sale”). In connection with the Elevation Sale, the Company received an upfront cash payment of $3.5 million. The Company is also eligible to receive up to $54.5 million in additional potential development, regulatory approval and commercial-based milestone payments, consisting of:

•

$3.0 million for achievement of the primary endpoint in the first registrational clinical study of either MM-121 or MM-111;

•

Up to $16.5 million in total payments for the achievement of various regulatory approval and reimbursement-based milestones in the United States, Europe and Japan; and

•

Up to $35.0 million in total payments for achieving various cumulative worldwide net sales targets between $100.0 million and $300.0 million for MM-121 and MM-111.

In January 2023, Elevation announced that it had paused further investment in the clinical development of seribantumab and intends to pursue further development only in collaboration with a partner. In January of 2024 Elevation announced that it is evaluating initiation of a development program utilizing a antibody drug conjugate (ADC) targeting HER3. Elevation has not

disclosed if this preclinical program utilizes intellectual property licensed from Merrimack. Elevation has also not provided a timeline indicating when this program could reach clinical trials or regulatory approval, if successful.

On January 23, 2023, the Company entered into another Asset Purchase Option Agreement (the “Option Agreement”) with another third party (the “Purchaser”), pursuant to which the Purchaser agreed to obtain an exclusive option (the “Option”) to purchase one of the Company’s preclinical programs with a consideration of $0.7 million. Under the terms of the Option Agreement, the Purchaser paid to the Company the Option fee of $0.2 million and the Company incurred transaction costs less than $0.1 million. A net gain of $0.1 million was recognized in January 2023. The Purchaser decided not to exercise the Option in July 2023.

The Company's remaining non-commercial assets, including its clinical and preclinical development programs, and all material other clinical and pre-clinical development programs have been sold with the exception of one program.

The Company is subject to risks and uncertainties common to companies in the biopharmaceutical industry, including, among other things, its ability to secure additional capital to fund operations, development by competitors of new technological innovations, protection of proprietary technology and compliance with government regulations. None of the Company’s product candidates sold to others or retained by the Company are approved for any indication by the FDA or any other regulatory agency. The Company operates in an environment of rapid change in technology and substantial competition from pharmaceutical and biotechnology companies, among others. In addition, the Company is dependent upon the services of its external consultants for the operation of the Company.

In accordance with Accounting Standards Codification (“ASC”) 205-40, Going Concern, the Company has evaluated whether there are conditions and events, considered in the aggregate, that raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date that the condensed consolidated financial statements are issued. As of March 31, 2024, the Company had an accumulated deficit of $347.4 million. During the three months ended March 31, 2024, the Company incurred net loss from continuing operations of $0.4 million and used $1.3 million of cash in operating activities. The Company expects to continue to generate operating losses for the foreseeable future. The Company expects that its cash and cash equivalents and short-term investments of $244.1 million at March 31, 2024 will be sufficient to fund operations for the foreseeable future.

Summary of Significant Accounting Policies (Policies)	3 Months Ended
Summary of Significant Accounting Policies (Policies)	Mar. 31, 2024
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying condensed consolidated financial statements reflect the operations of Merrimack Pharmaceuticals, Inc. and its wholly owned subsidiaries. All intercompany accounts and transactions have been eliminated. The condensed consolidated financial statements are unaudited and have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”). The accounting policies followed in the preparation of the interim condensed consolidated financial statements are consistent in all material respects with those presented in Note 1 to the financial statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2023.
Unaudited Interim Financial Information	Unaudited Interim Financial Information The condensed consolidated balance sheet as of December 31, 2023 was derived from audited financial statements for the year ended December 31, 2023, but does not include all disclosures required by GAAP. The condensed consolidated balance sheet as of March 31, 2024, the condensed consolidated statements of operations and comprehensive loss for the three months ended March 31, 2024 and 2023, the condensed consolidated statements of stockholders’ equity for the three months ended March 31, 2024 and 2023 and the condensed consolidated statements of cash flows for the three months ended March 31, 2024 and 2023 are unaudited. The unaudited interim condensed consolidated financial statements have been prepared on the same basis as the audited annual financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for the fair statement of the Company’s financial position as of March 31, 2024, the results of its operations for the three months ended March 31, 2024 and 2023, its statements of stockholders’ equity for the three months ended March 31, 2024 and 2023 and its statements of cash flows for the three months ended March 31, 2024 and 2023. The financial data and other information disclosed in the notes related to the three months ended March 31, 2024 and 2023 are unaudited. The results for the three months ended March 31, 2024 and 2023 are not necessarily indicative of results to be expected for the year ending December 31, 2024, any other interim periods, or any future year or period. The unaudited interim financial statements of the Company included herein have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”). Certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted from this report, as is permitted by such rules and regulations. These unaudited condensed consolidated financial statements should be read in conjunction with the audited financial statements and the notes thereto contained in the Company’s Annual Report on Form 10-K for the year ended December 31, 2023 filed with the SEC on March 7, 2024.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates, assumptions and judgments that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements and the reported amounts of expenses during the reporting periods. Significant estimates, assumptions and judgments reflected in these condensed consolidated financial statements include, but are not limited to, the accrual of research and development expenses and the valuation of stock-based awards. Estimates are periodically reviewed in light of changes in circumstances, facts and experience. Actual results could differ from the Company’s estimates.
Recent Accounting Pronouncements	From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (“FASB”) or other standard setting bodies that the Company adopts as of the specified effective date. Unless otherwise discussed above, the Company does not believe that the adoption of recently issued standards has or may have a material impact on the Company’s condensed consolidated financial statements or disclosures.