UPDATE: Immuneering (IMRX) - The Data Hit. The Stock Got Hit Harder.
The ASCO oral confirmed the 17.3-month median OS in n=55 — and added a consistency check the pre-release didn’t have. The stock is down 13.9% anyway.
Executive Summary: Sell-the-News, With a Twist
The Vu podium presentation at ASCO landed, and the data is exactly what the May 21 pre-release promised — and then some. 17.3-month median OS in the full n=55 cohort, 8.3-month mPFS, 36% confirmed ORR, 82% DCR, and 84% of patients maintaining or gaining weight at three months. The safety profile held: only anemia (16%) and neutropenia (18%) crossed the 10% Grade 3+ threshold, both chemo-driven, no Grade 4 atebimetinib-related events, no Grade 5s, one discontinuation.
Then the stock closed at $4.49, down 13.9% from $5.22 on May 21.
Welcome to biotech. The headline number was pre-released eleven days ago, the AACR/ASCO run-up priced in a strong topline, and today’s tape is the buyside taking profits on a single-arm trial that doesn’t read out the randomized version until 2028. None of that breaks the thesis. Some of it actually strengthens it.
The Receipts
The Consistency Check (the new piece). This is the data point the May 21 pre-release didn’t carry, and it’s the most important thing on the slide deck. The original n=34 cohort — with median follow-up now at 17.0 months — also posted a 17.3-month median OS (95% CI: 11.6, not reached). The full n=55 cohort, with shorter 11.6-month median follow-up, hit the same 17.3-month median (95% CI: 11.2, not reached).
The implication: the bear-case argument that “the median will keep dropping as follow-up matures” just got a clean refutation. The longer-followed subset didn’t degrade. The 21 new patients didn’t drag the number down. Two cohorts, two different follow-up durations, same median. That’s about as good a durability tell as you can get out of a single-arm trial.
The Response and PFS Numbers. The pre-release gave us mOS. ASCO gave us the full triad: 8.3-month mPFS (95% CI: 5.9, 9.6), 36% confirmed ORR (18/50), 82% DCR (41/50). The MPACT historical mPFS in the gem/nab-pac arm was 5.5 months — so this regimen extends PFS by roughly three months and OS by roughly nine. That OS-PFS discordance I flagged in the original deep dive (the survival benefit substantially exceeding the progression-free benefit) is now even more pronounced at maturity. The interpretation I offered then still applies: the drug appears to keep patients in a healthier state post-progression, allowing them to tolerate subsequent lines of therapy. The 84% weight stability number is the clinical-narrative scaffolding for that read.
The Safety Profile Refinement. Today’s data gives a more granular AE breakdown than prior disclosures. Grade 3+ events below the 10% threshold: rash (5%), fatigue (2%), vomiting (2%), peripheral edema (2%). For a MEK inhibitor, that rash number is the punchline. Trametinib’s chronic-inhibition profile drives Grade 3 rash in roughly 15-20% of patients depending on the regimen. 5% Grade 3 rash on atebimetinib + chemo is the slap-and-run mechanism doing exactly what the original deep dive said it would do — sparing healthy skin during the daily 20-hour drug-free window.
The Investor Call and Phase 3 Update. Management held the 8:00 a.m. EDT call. MAPKeeper 301 (NCT07562152) remains actively recruiting, first patient dosing on track for mid-2026, topline expected mid-2028. No surprises on timeline. No financing surprises — the fortress balance sheet ($198.6M as of Q1, runway into 2029) is unchanged.
