IMRX reports atebimetinib interim OS/PFS; concurrent $25M Aventis private placement contingent on $75M IPO
Immuneering Corporation (IMRX) is offering shares of its Class A common stock and pre-funded warrants, with a concurrent private placement with Aventis Inc., a wholly owned subsidiary of Sanofi, to purchase up to $25.0 million of stock contingent on a firm-commitment public offering that raises at least $75.0 million.
Clinical update: in a 320 mg once-daily atebimetinib plus modified gemcitabine/nab-paclitaxel cohort (N=34, cutoff August 26, 2025), Immuneering reported 86% overall survival and 53% progression-free survival at nine months, median PFS 9.6 months, median OS not reached; six-month rates were 94% OS and 70% PFS. Grade ≥3 TEAEs ≥10% included anemia (24%) and neutropenia (18%); no Grade 5 TEAEs reported.
The company’s Class A common stock trades on Nasdaq under IMRX (last reported sale $8.59 on September 23, 2025). Underwriters will receive a 6.0% commission and an option to purchase additional shares. The private placement shares will not be registered and are expected to close concurrent with the qualified public offering.
Positive
- Interim clinical efficacy: 320 mg atebimetinib plus mGnP cohort reported 86% OS and 53% PFS at nine months (N=34) with median PFS 9.6 months
- No Grade 5 TEAEs: safety update reported no Grade 5 events and no new safety signals at the cutoff date
- Strategic investor interest: Aventis Inc. (Sanofi subsidiary) agreed to purchase up to $25.0 million in a concurrent private placement (subject to conditions)
- Nasdaq listing and recent price: Class A common stock trades under IMRX, last reported sale $8.59 on September 23, 2025
Negative
- Private placement contingency: Aventis commitment is contingent on a qualified public offering that raises at least $75.0 million and public pricing announced by Sept 26, 2025
- Immediate dilution: company discloses existing net tangible book value $0.51 per share as of June 30, 2025 and states new investors will incur immediate dilution (specific per-share dilution amounts redacted)
- Significant Grade ≥3 adverse events: anemia (24%) and neutropenia (18%) occurred at Grade ≥3 in the 320 mg ITT population
- Pre-funded warrants illiquidity: no public market is expected for the pre-funded warrants and they will not be listed
Insights
TL;DR: Clinical interim data plus a conditional $25M investor commitment support near-term financing but depend on a $75M qualified public offering.
The announced interim atebimetinib data (N=34) show survival and PFS rates at six and nine months that the company contrasts versus reconstructed MPACT estimates. The financing structure pairs an underwritten public offering with a contingent $25M private placement from a Sanofi subsidiary, aligning strategic investor interest with a minimum public raise threshold. The offering will dilute existing holders; underwriting fees of 6% apply. These are material near-term capital and commercial-readout developments relevant to liquidity and runway.
TL;DR: Atebimetinib plus mGnP interim results in first-line pancreatic cancer show encouraging survival and tolerability signals in a 34-patient cohort.
The 320 mg cohort reported median PFS of 9.6 months and not-yet-reached median OS with nine-month OS/PFS of 86%/53% and six-month OS/PFS of 94%/70%. Reported Grade ≥3 toxicities were primarily hematologic (anemia 24%, neutropenia 18%), with no Grade 5 events and no new safety signals through the cutoff date. Data are single-arm and non-randomized; the company plans regulatory feedback on Phase 3 plans in Q4 2025 and anticipates potential Phase 3 initiation by end of 2025 pending that feedback.
Registration No. 333-289589
(To Prospectus dated August 20, 2025)
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ABOUT THIS PROSPECTUS SUPPLEMENT
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CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS
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PROSPECTUS SUPPLEMENT SUMMARY
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THE OFFERING
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DILUTION
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CERTAIN U.S. FEDERAL INCOME TAX CONSEQUENCES
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WHERE YOU CAN FIND MORE INFORMATION; INCORPORATION BY REFERENCE
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SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS
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WHERE YOU CAN FIND MORE INFORMATION; INCORPORATION BY REFERENCE
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RISK FACTORS
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USE OF PROCEEDS
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DESCRIPTION OF CAPITAL STOCK
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DESCRIPTION OF DEBT SECURITIES
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DESCRIPTION OF WARRANTS
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DESCRIPTION OF UNITS
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PLAN OF DISTRIBUTION
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EXPERTS
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245 Main Street, Second Floor
Cambridge, MA 02142
(617) 500-8080
Preferred Stock
Debt Securities
Warrants
Units
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ABOUT THIS PROSPECTUS
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SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS
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WHERE YOU CAN FIND MORE INFORMATION; INCORPORATION BY REFERENCE
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THE COMPANY
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RISK FACTORS
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USE OF PROCEEDS
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DESCRIPTION OF CAPITAL STOCK
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DESCRIPTION OF DEBT SECURITIES
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DESCRIPTION OF WARRANTS
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DESCRIPTION OF UNITS
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GLOBAL SECURITIES
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PLAN OF DISTRIBUTION
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LEGAL MATTERS
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EXPERTS
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245 Main Street, Second Floor
Cambridge, MA 02142
(617) 500-8080