Atebimetinib Combinations with Anti-PD1 Cured 50% of Mice in a RAS-Mutant Colorectal Cancer Model and Nearly Doubled Survival in a RAS-Mutant Lung Cancer Model; New Data Presented at SITC 2026
Complete tumor regressions persisted after treatment stopped in the colorectal mouse model.
Sentiment and the balance of points
Rhea-AI Sentiment reads the wording of the document, how positive or negative its language is on a 1 to 5 scale. The balance of points shown with the takes weighs what the document actually discloses, so the two can disagree, for example when a trial that missed its main goal is described in upbeat language.
Rhea-AI Summary
Immuneering (Nasdaq: IMRX) reported preclinical atebimetinib combination results, including complete tumor regression in 50% of mice in a colorectal cancer model.
In the RAS-mutant colorectal model, atebimetinib plus anti-PD-1 achieved complete regression in 6 of 12 mice at each tested dose, with no regrowth after treatment stopped; median survival was not reached. In the RAS-mutant lung model, adding atebimetinib to anti-PD-1 and chemotherapy extended median survival to 25 days versus 14 days, a 1.8-fold improvement. The results are being presented at SITC 2026. Immuneering expects its Phase 2 trial of atebimetinib with anti-PD-1 and platinum-doublet chemotherapy in previously untreated RAS-mutant non-small cell lung cancer to dose its first patient by year-end 2026.
Positive
- Minor pointColorectal-model combination achieved 50% complete regression at each tested dose, without regrowth after treatment stopped.
- Minor pointColorectal-model combination median survival was not reached, outperforming the single-agent treatment groups.
- Minor pointLung-model combination extended median survival to 25 versus 14 days with anti-PD-1 plus chemotherapy alone.
- Minor pointLung-model combination had 12 of 12 mice alive at Day 18, versus none with anti-PD-1 plus chemotherapy.
- Minor point. Forward-looking: it has not happened yet and may not happen.Immuneering expects first Phase 2 patient dosing by year-end 2026 for the first-line lung cancer combination trial.
Negative
- None.
Key Figures
- Complete tumor regression
- 50% (6 of 12 mice)
- CT-26 colorectal model; atebimetinib plus anti-PD-1
- Median survival
- 25 days vs. 14 days (1.8-fold improvement)
- LL2 lung model; 125 mg/kg BID triple combination vs. anti-PD-1 plus chemotherapy
- Survival at Day 18
- 12 of 12 mice vs. 0 of 12 mice
- LL2 lung model; triple combination vs. anti-PD-1 plus chemotherapy
- P-value
- P<0.0001
- Versus vehicle for nearly all colorectal model combinations
- First patient dosing
- By year-end
- Expected start of the Phase 2 first-line RAS-mutant NSCLC combination trial
Historical Context
-
Prior SITC notice described preclinical PD-1 combination findings supporting a planned Phase 2 lung study.
24h Move is the share-price change in the day after each event; other market factors may also have contributed.
Key Terms
anti-pd-1 medical
mek inhibitor medical
mapk pathway medical
syngeneic medical
nsclc medical
AI-generated analysis. How Rhea-AI works. Not financial advice.
- Durable complete regressions observed in
- Median survival extended by 1.8-fold with atebimetinib plus anti-PD-1 and chemotherapy versus anti-PD-1 plus chemotherapy alone in a RAS-mutant lung cancer model -
- Pulsatile MEK inhibition reversed MAPK-driven immune suppression by lowering suppressive myeloid cells and regulatory T-cells, and expanding NK cells, while avoiding T-cell signaling attenuation associated with continuous MAPK inhibition -
- Phase 2 clinical trial of atebimetinib in combination with anti-PD-1 and platinum-doublet chemotherapy in first-line RAS-mutant NSCLC is expected to dose the first patient by year-end -
NEW YORK, Nov. 06, 2026 (GLOBE NEWSWIRE) -- Immuneering Corporation (Nasdaq: IMRX), a late-stage clinical oncology company focused on keeping cancer patients alive and helping them thrive, today announced compelling preclinical data demonstrating that atebimetinib, the Company’s novel Deep Cyclic Inhibitor of MEK, enhanced the activity of PD-1 checkpoint blockade in RAS-mutant colorectal and lung cancer models, including a
“Curing
In the CT-26 syngeneic mouse model of colorectal cancer, both the 75 mg/kg and 125 mg/kg atebimetinib plus anti-PD-1 groups achieved complete tumor regression in 6 of 12 mice (
In the LL2 syngeneic lung cancer model, a PD-1-cold model unresponsive to anti-PD-1 monotherapy, atebimetinib demonstrated enhanced antitumor activity in combination with anti-PD-1 and platinum-doublet chemotherapy. At 125 mg/kg BID, atebimetinib plus anti-PD-1, carboplatin and pemetrexed extended median survival to 25 days, compared with 14 days for anti-PD-1 plus chemotherapy alone, representing a 1.8-fold improvement. All 12 mice receiving the triple combination were alive at Day 18, compared with none of the 12 mice receiving anti-PD-1 plus chemotherapy alone. These data support further clinical investigation of this combination in first-line RAS-mutant non-small cell lung cancer (NSCLC).
Presentation Details:
Title: “Cyclic disruption of the mitogen-activated protein kinase (MAPK) pathway by the pulsatile MEK inhibitor, Atebimetinib, enhances PD-1 checkpoint blockade in RAS mutant tumors.”
Abstract: #377
Presenting Author: Amy E. Axel, Immuneering Corporation
Presentation: Friday, November 6, 2026
Following presentation, the poster will be available on the publications section of Immuneering’s website at https://immuneering.com/publications.
About Immuneering Corporation
Immuneering is a late-stage clinical oncology company dedicated to keeping cancer patients alive and helping them thrive, with an initial focus on patients with RAS, RAF, and other MAPK-driven cancers. The Company is developing an entirely new category of cancer medicines, Deep Cyclic Inhibitors, designed to improve overall survival by three mechanisms: shrinking tumors durably with less resistance, preserving body mass by countering cachexia, and minimizing side effects to maximize performance status and combinability. Immuneering’s lead product candidate, atebimetinib, is an oral, once-daily Deep Cyclic Inhibitor of MEK, designed to improve survival across many cancer indications. The Company is conducting a global randomized pivotal trial, MAPKeeper 301, evaluating atebimetinib in combination with chemotherapy in first-line pancreatic cancer patients. The Company’s development pipeline also includes additional combination opportunities and preclinical stage programs. For more information, please visit www.immuneering.com.
Forward-Looking Statements
This press release contains forward-looking statements, including within the meaning of the Private Securities Litigation Reform Act of 1995. All statements contained in this press release that do not relate to matters of historical fact should be considered forward-looking statements, including, without limitation, statements regarding: the treatment potential of atebimetinib, alone or in combination with other agents to treat cancer, including anti-PD-1 therapy and platinum-doublet chemotherapy; the timing, design and initiation of the Phase 2 study of atebimetinib in combination with anti-PD-1 therapy and chemotherapy; the translation of preclinical efficacy and immune profiling findings to patients, including that combining a pulsatile inhibitor of MEK with an immunotherapy may lead to enhanced activity.
These forward-looking statements are based on management’s current expectations. These statements are neither promises nor guarantees, but involve known and unknown risks, uncertainties and other important factors that may cause our actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements, including, but not limited to, the following: we are a late-stage clinical oncology company with a limited operating history and have not completed any registrational clinical trials; we have incurred significant losses, are not currently profitable and may never become profitable; limitations on our cash runway and potential increases in expenditures; our need for additional funding; our unproven approach to therapeutic intervention; our ability to address regulatory questions and changing regulatory standards, and the uncertainties relating to regulatory filings, reviews and approvals; the lengthy, expensive, and uncertain process of clinical drug development, including the uncertainty of whether positive preclinical or early clinical efficacy and safety results are confirmed in later-stage trials, potential delays in activation of trial sites or enrollment of trial participants, or failure to obtain regulatory approvals; our reliance on third parties and collaborators to conduct our clinical trials, manufacture our product candidates, and develop and commercialize our product candidates, if approved; failure to compete successfully against other drug companies; protection of our proprietary technology and the confidentiality of our trade secrets; potential lawsuits for, or claims of, infringement of third-party intellectual property or challenges to the ownership of our intellectual property; our patents being found invalid or unenforceable; costs and resources of operating as a public company; and unfavorable or no analyst research or reports.
These and other important factors discussed under the caption “Risk Factors” in our Quarterly Report on Form 10-Q for the period ended September 30, 2026, and our other reports filed with the U.S. Securities and Exchange Commission, could cause actual results to differ materially from those indicated by the forward-looking statements made in this press release. Any such forward-looking statements represent management's estimates as of the date of this press release. While we may elect to update such forward-looking statements at some point in the future, except as required by law, we disclaim any obligation to do so, even if subsequent events cause our views to change. These forward-looking statements should not be relied upon as representing our views as of any date subsequent to the date of this press release.
Investor Contact:
Laurence Watts
New Street Investor Relations
laurence@newstreetir.com
Media Contact:
David Caouette
dcaouette@immuneering.com
FAQ
AI-generated questions and answers. How Rhea-AI works. Not financial advice.
What did Immuneering’s atebimetinib combination show in the colorectal cancer mouse model?
Atebimetinib plus anti-PD-1 produced complete tumor regression in 6 of 12 mice (50%) in each of the 75 mg/kg and 125 mg/kg groups. No regrowth occurred after treatment stopped, and median survival was not reached in the combination groups.
When does Immuneering expect its atebimetinib Phase 2 lung cancer trial to start dosing?
Immuneering expects to dose the first patient by year-end 2026. The Phase 2 trial will evaluate atebimetinib with anti-PD-1 and platinum-doublet chemotherapy as first-line treatment for RAS-mutant non-small cell lung cancer.
Which atebimetinib dose and chemotherapy drugs were tested in Immuneering’s lung cancer mouse study?
The lung cancer mouse study tested atebimetinib at 125 mg/kg twice daily with anti-PD-1, carboplatin and pemetrexed. The LL2 model was unresponsive to anti-PD-1 given alone.