On November 12, 2026 Immuneering Corporation (Nasdaq: IMRX), a late-stage clinical oncology company focused on keeping cancer patients alive and helping them thrive, reported plans to initiate a Phase 2 clinical trial evaluating atebimetinib in combination with chemotherapy in patients with anaplastic thyroid cancer (ATC), a highly aggressive form of thyroid cancer with significant unmet need, commonly driven by BRAF or RAS mutations.

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Immuneering plans to submit an Investigational New Drug (IND) application to the U.S. Food and Drug Administration (FDA) for the program by the end of 2026. Subject to regulatory clearance, Immuneering currently expects to dose the first patient in the study in mid-2027, with topline results potentially available 12-18 months after dosing begins. The preliminary study plan is to enroll approximately 60 patients with ATC who progressed on standard of care, including an all-comers cohort and a BRAF V600E cohort. The study is designed to be potentially registrational, pending discussion with regulators.

ATC is one of the fastest growing and most aggressive forms of cancer. While it accounts for a small percentage of all thyroid cancers, its rapid progression and poor prognosis result in a disproportionately high share of thyroid cancer-related deaths. It is commonly driven by the MAPK pathway. BRAF mutations are the most frequently occurring alterations, and the majority of patients have tumors driven by either BRAF mutations or RAS mutations. New treatment options capable of delivering durable tumor control while maintaining tolerability are urgently needed.

"Anaplastic thyroid cancer remains one of the most challenging malignancies we encounter, with tumors that can progress extraordinarily quickly and limited treatment options for many patients," said Alan Ho, M.D., Ph.D., Chief of the Head and Neck Oncology Service at Memorial Sloan Kettering Cancer Center. "Despite important advances for certain molecularly defined subsets of patients, there remains a substantial need for new therapeutic approaches that can provide durable disease control for a broader population of patients with ATC."

"Atebimetinib has the potential to help patients with many different types of cancer, and to be synergistic in many different combinations," said Ben Zeskind, Ph.D., Co-founder and Chief Executive Officer of Immuneering. "The exciting results we have observed to date with atebimetinib in combination with chemotherapy in pancreatic cancer has reinforced our conviction in this approach. With MAPK pathway activation a defining feature of anaplastic thyroid cancer, and BRAF and RAS mutations among its key drivers, deep cyclic inhibition of MAPK signaling with atebimetinib represents an innovative, promising therapeutic approach in combination with chemotherapy for addressing the significant unmet need in anaplastic thyroid cancer. We are grateful to the esteemed group of world-class thyroid cancer experts who have helped design this study and encouraged us to pursue it with a high degree of optimism, and together we are moving full speed ahead."

The scientific rationale supporting the planned clinical program will be highlighted in a preclinical poster at the 38th EORTC-NCI-AACR (Free EORTC-NCI-AACR Whitepaper) Symposium on Molecular Targets and Cancer Therapeutics, taking place November 18-20, 2026, in Barcelona, Spain.

Poster Presentation Details:
Title: Atebimetinib, a deep cyclic inhibitor of MEK, combined with chemotherapy: preclinical rationale for treatment of anaplastic thyroid cancer (ATC).
Abstract Number: 144
Poster Number: PB-144
Presenter: Praveen Nair
Date: Wednesday, November 18, 2026

Following presentation, the poster is expected to be available on the publications section of Immuneering’s website.

Conference Call
Immuneering will host a conference call and live webcast at 8:30 a.m. EST on November 12, 2026, to discuss today’s news announcements. Individuals interested in listening to the live conference call may do so by dialing (800) 715-9871 for U.S. callers and (646) 307-1963 for other locations and reference conference ID 6087332, or from the webcast link in the "investors" section of the company’s website at www.immuneering.com. A webcast replay will be available in the investor relations section on the company’s website for 90 days following the completion of the call.

About Anaplastic Thyroid Cancer
Anaplastic thyroid cancer, or ATC, is a rare and highly aggressive form of thyroid cancer characterized by rapid tumor growth and invasion into surrounding tissues. According to the National Cancer Institute, ATC accounts for approximately 1% to 2% of thyroid cancer cases and affects approximately one to two people per million each year in the United States. Unlike most other forms of thyroid cancer, ATC can progress extremely rapidly and frequently presents with locally advanced or metastatic disease. Standard of care chemotherapy remains a primary treatment option for ATC, however these cytotoxic agents can induce MAPK reactivation, potentially limiting response durability. Although advances in targeted therapies have improved outcomes for some patients with specific molecular alterations, there remains a substantial unmet need for new treatment approaches capable of providing durable disease control across a broader population of patients with ATC.

About Atebimetinib
Atebimetinib is the first in a new category of oral drug candidates, Deep Cyclic Inhibitors (DCIs), 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. Each of these mechanisms has been well established to improve survival in published studies. DCIs challenge the conventional model of sustained or continuous inhibition in oncology. Whereas most therapies are designed for sustained inhibition, driving cancer to adapt and develop resistance so tumors shrink quickly but temporarily, DCIs are designed to pulse faster than tumors can adapt, so tumors shrink slowly but durably. Moreover, DCIs aim to restore full transient signaling to healthy cells, with the goal of leading to fewer adverse events. Atebimetinib targets MEK, a key control point in the MAPK pathway (RAS-RAF-MEK-ERK), which is pathologically activated in a majority of cancers, including approximately 97% of pancreatic cancers. Targeting MEK blocks a broader range of MAPK pathway alterations because it is further downstream, creating the potential for more durable benefit.

(Press release, Immuneering, NOV 12, 2026, View Source [SID1234674695])