Immunome proposes $400 million stock offering, later sets $21.50 price

Immunome, Inc. (Nasdaq: IMNM) said on December 15, 2025 that it planned an underwritten public offering of $400 million of common stock, with a 30-day option for the underwriters to buy up to $60 million more. All of the shares would be issued by the company. The company said there was no assurance the offering would be completed, or what its final size or terms would be. The deal is made under a Form S-3 shelf registration that was filed on February 13, 2024 and became effective on filing.

Underwriters, counsel and the sales agreement

Leerink Partners, J.P. Morgan, TD Cowen, Goldman Sachs & Co. LLC and Guggenheim Securities are joint bookrunning managers. Wedbush PacGrow and LifeSci Capital are co-lead managers. Latham & Watkins, LLP, of San Diego, is counsel to the underwriters. Cooley LLP, also of San Diego, is Immunome's counsel on the offering.

Immunome also has a sales agreement with TD Securities (USA) LLC for an at-the-market program capped at $200.0 million. The prospectus supplement says $134.1 million of that capacity remains available.

Pricing on December 16

On December 16, 2025, Immunome set the final terms in a prospectus supplement dated that day. It sold 18,625,000 shares at $21.50 per share, or $400,437,500 in total. Underwriting discounts and commissions came to $1.29 per share, or $24,026,250, leaving $376,411,250 before expenses. The company estimated net proceeds at approximately $375.9 million. The underwriters hold a 30-day option on an additional 2,793,750 shares, which would raise estimated net proceeds to approximately $432.3 million. Delivery of the shares was expected on or about December 18, 2025.

Chief Executive Officer and Chairman Clay Siegall is purchasing 46,511 shares in the offering at the public offering price, and the underwriters receive the same discount on those shares as on any other.

The Phase 3 result and its limits

Immunome says it announced positive topline data from the Phase 3 RINGSIDE trial of varegacestat in December 2025 and anticipates submitting an NDA in Q2 2026. The prospectus supplement does not give the topline results, so readers have only the company's word that they were positive.

The response figures the company cites come from the earlier Phase 2 study, RINGSIDE Part A. There the objective response rate was 75% of evaluable patients and 64% in the intent-to-treat population. The company says the Phase 2 safety profile is consistent with other gamma secretase inhibitors, but that is its own description.

Varegacestat would not be the first gamma secretase inhibitor for desmoid tumors. The FDA approved nirogacestat, sold as OGSIVEO, in November 2023 for progressing tumors that need systemic treatment.

Other programs

IM-1021, a ROR1-targeted antibody-drug conjugate, dosed its first patient in a Phase 1 trial in February 2025, and the company plans initial data in 2026. IM-3050, a fibroblast activation protein-targeted radioligand therapy, received IND clearance in April 2025, with a Phase 1 start planned for early 2026.

Use of proceeds and dilution

Immunome would use the proceeds, with existing cash, for the potential commercial launch of varegacestat, its manufacturing scale-up, other development and working capital. It has no current commitments to in-license or acquire other assets.

The company had 91,706,948 shares of common stock outstanding on September 30, 2025, and the final prospectus puts the count at 110,331,948 after the offering, or 113,125,698 if the option is exercised in full. Those counts exclude 15,695,808 shares issuable on exercise of stock options at a weighted-average exercise price of $10.09 per share. Historical net tangible book value was $263.9 million, or $2.88 per share, at September 30, 2025. The prospectus says buyers in the offering face immediate dilution of approximately $15.70 per share, with further dilution possible from option exercises and from sales under the sales agreement.

The prospectus gives no current cash balance and no 2025 net loss, so it does not show how much spending the offering would cover.

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