☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q For the quarterly period ended September 30, 2023 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission file number 0-17999 ImmunoGen, Inc. Massachusetts 04-2726691 (State or other jurisdiction of incorporation or organization) 830 Winte ...

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2023 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission file number 0-17999 ImmunoGen, Inc. Large accelerated filer ⌧ Accelerated filer ◻ Non-accelerated filer ◻ Smaller reporting company ☐ Emer ...

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2023 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission file number 0-17999 ImmunoGen, Inc. Massachusetts 04-2726691 (State or other jurisdiction of incorporation or organization) 830 Winter St ...

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Table of Contents Form 10-K For the year ended December 31, 2022 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the period from to Commission file number 0-17999 ImmunoGen, Inc. Massachusetts (State or other jurisdiction of incorporation or organization) 04-2726691 (I.R.S. Employer Identification No.) ☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 ...

Financial Performance - Total revenues for the three months ended June 30, 2022, were $14.2 million, a decrease of 16.4% compared to $16.9 million for the same period in 2021[15]. - The net loss for the six months ended June 30, 2022, was $86.2 million, compared to a net loss of $64.8 million for the same period in 2021, indicating an increase in losses of approximately 32.9%[15]. - The basic and diluted net loss per common share for the three months ended June 30, 2022, was $0.24, compared to $0.15 for the same period in 2021[15]. - The company reported a net loss of $62,021,000 for the three months ended June 30, 2022, compared to a net loss of $30,741,000 for the same period in 2021, indicating an increase in loss of approximately 102.5%[15]. - The company reported a net loss of $86.2 million for the six months ended June 30, 2022, compared to a net loss of $64.8 million for the same period in 2021[21]. Assets and Liabilities - As of June 30, 2022, total assets decreased to $422.3 million from $525.8 million as of December 31, 2021, representing a decline of approximately 19.6%[13]. - Total current liabilities decreased to $87.1 million as of June 30, 2022, from $100.9 million as of December 31, 2021, a reduction of approximately 13.7%[13]. - The total shareholders' equity decreased to $249.8 million as of June 30, 2022, from $325.6 million at the end of 2021, a decline of approximately 23.2%[13]. - The company’s accumulated deficit increased to $1,557,309,000 as of June 30, 2022, compared to $1,471,143,000 as of December 31, 2021, indicating an increase of approximately 5.8%[13]. Cash Flow - The company reported cash and cash equivalents of $373.9 million as of June 30, 2022, down from $478.8 million at the end of 2021, a decrease of 22%[13]. - The company had net cash used for operating activities of $105.4 million for the six months ended June 30, 2022, compared to $88.5 million for the same period in 2021[21]. - Cash and cash equivalents as of June 30, 2022, were $373.9 million, down from $478.8 million as of December 31, 2021[129]. Research and Development - Research and development expenses for the three months ended June 30, 2022, were $51.4 million, up 48.7% from $34.6 million in the same period of 2021[15]. - The company anticipates continued investment in research and development to support future product candidates and business strategies[8]. - The company expects to continue incurring substantial operating losses in the near term due to significant expenses related to research and development[21]. - Total research and development expenses rose to $51.4 million for the six months ended June 30, 2022, an increase of $16.8 million compared to $34.6 million in 2021[119]. Revenue Recognition - The company expects to recognize revenue on approximately 26%, 62%, and 12% of remaining performance obligations over the next 12 months, 13 to 60 months, and 61 to 120 months, respectively[27]. - The aggregate amount of deferred revenue as of June 30, 2022, was $59.2 million, reflecting a decrease from $92.1 million at the end of 2021[28]. - The company recognized $36.6 million in revenue from amounts included in contract liabilities at the beginning of the period for the six months ended June 30, 2022[28]. - License and milestone fee revenue increased by $6.7 million and $37.5 million for the three and six months ended June 30, 2022, respectively, compared to the same periods in 2021[116]. Strategic Initiatives - The company plans to explore market expansion opportunities and potential strategic partnerships to enhance growth prospects[8]. - The company plans to raise additional funds through equity, debt, or other financings to support its operational activities[22]. - The company has selectively licensed its ADC platform technology to other companies, which may provide upfront fees, milestone payments, and royalties on sales[106]. Stock and Compensation - Stock compensation expense related to stock options and restricted stock unit awards was $4.8 million and $9.0 million for the three and six months ended June 30, 2022, respectively, compared to $3.6 million and $7.3 million for the same periods in 2021[51]. - The estimated fair value of unvested employee awards, excluding performance awards, was $50.1 million as of June 30, 2022, with a weighted-average remaining vesting period of approximately three years[51]. - The Company had 29,528 options outstanding as of June 30, 2022, compared to 21,681 options in the same period of 2021[44]. Collaborations and Agreements - The Company received a non-refundable upfront payment of $13.0 million from Eli Lilly under a license agreement, with potential additional fees of $32.5 million and up to $1.7 billion in milestone payments[55]. - The collaboration with Huadong includes a $40.0 million upfront payment and potential milestone payments of approximately $265.0 million[65]. - The license agreement with Viridian includes potential milestone payments of up to $143.0 million plus royalties on commercial sales[67].

Financial Performance - Total revenues for the three months ended March 31, 2022, were $38,078,000, a significant increase from $15,706,000 in the same period of 2021, representing a growth of 142%[14] - The net loss for the three months ended March 31, 2022, was $24,145,000, compared to a net loss of $34,051,000 for the same period in 2021, indicating a reduction in losses by approximately 29%[14] - The company reported a basic and diluted net loss per common share of $0.10 for the three months ended March 31, 2022, compared to $0.17 for the same period in 2021[14] - The total shareholders' equity as of March 31, 2022, was $306,468,000, down from $325,586,000 at the end of 2021, a decrease of approximately 6%[13] - The company incurred a net loss of $24.1 million for the three months ended March 31, 2022, with an accumulated deficit of approximately $1.5 billion[21] Cash and Liabilities - Cash and cash equivalents decreased to $437,661,000 as of March 31, 2022, down from $478,750,000 at the end of 2021, a decline of approximately 9%[13] - Total current liabilities decreased to $84,118,000 as of March 31, 2022, from $100,945,000 at the end of 2021, a reduction of about 17%[13] - As of March 31, 2022, the company had no marketable securities, and its cash equivalents primarily consisted of money market funds[31] Research and Development - Research and development expenses increased to $44,282,000 for the three months ended March 31, 2022, up from $34,413,000 in the prior year, reflecting a rise of 29%[14] - The company anticipates continued growth in revenues driven by new product developments and market expansion strategies[8] - The management highlighted ongoing investments in research and development to support future product candidates and business strategies[9] - ImmunoGen, Inc. expects to continue incurring substantial operating losses in the near term due to significant research and development expenses[21] Revenue Recognition - The aggregate amount of deferred revenue as of March 31, 2022, was $70.1 million, with expected revenue recognition of approximately 33% in the next 12 months[27] - During the three months ended March 31, 2022, the company recognized $21.6 million in license and milestone fee revenue from a collaboration with Hangzhou Zhongmei Huadong Pharmaceutical Co., Ltd.[28] - The company received an upfront payment of $13.0 million from Eli Lilly and Company, with $9.2 million recognized as revenue during the same period[28] - The company recognized $4.1 million of previously deferred non-cash royalty revenue related to KADCYLA® royalties during the three months ended March 31, 2022[28] - The company expects to recognize revenue on approximately 33%, 55%, and 12% of the remaining performance obligations over the next 12 months, 13 to 60 months, and 61 to 120 months, respectively, from a deferred revenue balance of $70.1 million[27] Risks and Uncertainties - The management's discussion highlighted ongoing risks and uncertainties that may affect future performance, emphasizing the need for cautious investment considerations[10] - The company is subject to common risks in the biotechnology industry, including competition and dependence on key personnel[23] - The company plans to address known and unknown risks that may impact future performance as outlined in the "Risk Factors" section of the report[10] Stock and Compensation - As of March 31, 2022, the Company had 26,937 stock options outstanding with a weighted average exercise price of $6.08, an increase from 21,219 options at December 31, 2021[46] - Stock compensation expense for stock options and restricted stock unit awards was $4.2 million for the three months ended March 31, 2022, compared to $3.7 million for the same period in 2021[48] - The estimated fair value of unvested employee awards, excluding performance awards, was $46.9 million as of March 31, 2022, with a weighted-average remaining vesting period of approximately three years[48] Future Financing - The company may raise additional funds through equity, debt, or other financings, but there is no assurance that it will be able to do so on acceptable terms[22] - The Company has noncancelable manufacturing commitments totaling $18.3 million for in-process and future manufacturing of antibody and drug substances as of March 31, 2022[84] Other Financial Metrics - The weighted average discount rate for the operating lease liability is approximately 11%, with total lease liabilities amounting to $18.025 million[79] - The Company recorded $1.2 million in sublease income for each of the three months ended March 31, 2022, and 2021[81] - The Company expects a significant decrease in its 2022 tax loss due to the capitalization of research and development expenses as per the Tax Cuts and Jobs Act of 2017[69]

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Form 10-K ☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the year ended December 31, 2021 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the period from to Commission file number 0-17999 ImmunoGen, Inc. Massachusetts (State or other jurisdiction of incorporation or organization) 04-2726691 (I.R.S. Employer Identification No.) ...

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended September 30, 2021 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission file number 0-17999 ImmunoGen, Inc. Massachusetts 04-2726691 (State or other jurisdiction of incorporation or organization) (I.R.S. E ...

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission file number 0-17999 ImmunoGen, Inc. Washington, D.C. 20549 FORM 10-Q ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2021 OR Massachusetts 04-2726691 (State or other jurisdiction of incorporation or organization) (I.R.S. Employ ...

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2021 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission file number 0-17999 ImmunoGen, Inc. Massachusetts 04-2726691 (State or other jurisdiction of incorporation or organization) (I.R.S. Emplo ...