TREOS Bio Presents New PEPI Technology Data at EACR 2026, Including Six-Year Cancer-Free Outcome in MSS Metastatic Colorectal Cancer (mCRC)

LONDON and BOSTON and BUDAPEST, Hungary, June 09, 2026 (GLOBE NEWSWIRE) -- Treos Bio, a clinical-stage company developing off-the-shelf and personalized active cancer immunotherapies, today announced three abstracts on its proprietary Promiscuous EPItopes (PEPI) Technology accepted for presentation at the European Association for Cancer Research (EACR) 2026 Congress in Budapest, June 8–11.

The lead clinical finding is from the OBERTO-101 trial in MSS mCRC, a tumor type that has historically responded poorly to currently available immunotherapy approaches. A patient treated with PolyPEPI1018 at Mayo Clinic in 2019 remains disease-free 77.2 months later, with pathological complete response confirmed across resected tissues, including liver lesions.

MSS disease represents the vast majority of colorectal cancer patients and remains one of the largest unmet needs in cancer immunotherapy. PolyPEPI1018 is TREOS Bio's lead off-the-shelf multi-peptide immunotherapy candidate, already tested in three phase I/II clinical trials. If clinical efficacy continues to be demonstrated, its off-the-shelf design could offer important practical and commercial advantages compared with fully individualized approaches, including simpler logistics, faster treatment availability and broader scalability.

The presentations reinforce several elements of TREOS Bio's strategy: advancing PolyPEPI1018 in MSS mCRC, demonstrating the potential of the PEPI platform to support target selection without requiring tumor biopsy, and extending the platform into additional difficult-to-treat cancers, including EGFR-mutant non-small cell lung cancer (NSCLC).

"These presentations highlight the potential of TREOS Bio's PEPI Technology to support target prediction, broad T-cell activation and durable clinical benefit in difficult-to-treat cancers," said Sunjeet Sawhney, Chief Executive Officer of TREOS Bio. "They also reinforce the rationale for advancing PolyPEPI1018 in combination with standard therapies, while applying the PEPI Platform to additional immune-refractory cancers where current options remain limited."

OBERTO-101: Long-Term Pathological Complete Response in MSS mCRC
Co-authored by Dr. Mojun Zhu (Mayo Clinic), Dr. Joleen Hubbard (Allina Health Cancer Institute) and the Treos Bio scientific team, the case describes subject 01-0007: a patient with initially unresectable liver metastases plus lesions in the colon, lung and diffuse lymphadenopathy. After FOLFOX/cetuximab induction, the patient entered OBERTO-101 (NCT03391232) and received three doses of PolyPEPI1018 on top of standard fluoropyrimidine-based maintenance therapy. Tumor shrinkage led to partial response at week 36 and cuative R0 surgery at week 56. Surgical pathology showed no viable tumor cells across the liver, colon and all 27 resected lymph nodes, and the patient remains disease-free.

Translational analyses documented broad immune activation, including:

• T-cell responses against all seven PolyPEPI1018-targeted antigens;
• Increases in tumor-infiltrating lymphocytes (CD3+ and CD8+ cells) after the third dose;
• PolyPEPI1018-specific T-cell clonotypes detected in blood and tumor tissue, supporting intratumoral expansion of treatment-induced immune responses targeting non-mutated shared antigens in MSS mCRC.
  
  
  

EGFR-mutant NSCLC: Personalized Immunotherapy Followed by Tumor Regression on Sequential EGFR-TKI Therapy
A second case describes a 59-year-old with metastatic EGFR-mutant NSCLC and brain metastases, whose disease had progressed despite radiotherapy, EGFR-TKIs, chemotherapy and chemo-immunotherapy.

Under the German "individueller Heilversuch" regulatory framework, the patient received an 11-peptide personalized immunotherapy designed without tumor biopsy, using the patient's HLA genotype and TREOS Bio's PEPI Panel platform.

• De novo T-cell responses against 7/11 peptides (no baseline responses);
• Subsequent tumor RNA-sequencing confirmed expression of 8/11 predicted antigens;
• After treatment, subsequent osimertinib produced sustained regression of lung and brain lesions, ongoing >9 months, with gene-expression signatures of an activated tumor microenvironment.
  
  

PEPI Panel: Rapid Target Selection Without Tumor Biopsy
The third abstract introduces the PEPI Panel, a library of 3,286 synthetic long peptides covering 184 shared tumor antigens across 19 indications. Built using proprietary data from more than 100,000 tumors and 15,693 HLA genotypes, the Panel is designed to identify peptide targets predicted to be immunogenic for individual patients using only a saliva or blood sample:

• across 11 patients with seven tumor types, the PEPI Panel predicted approximately 70% of each patient's top tumor-expressed antigens;
• in 6 patients receiving PEPI-guided immunotherapies, 83% (60/72) of selected peptides induced T-cell responses.
  
  

PEPI Panel-based treatments can be designed in days, supporting a potentially faster and less invasive approach to personalized cancer immunotherapy.

About Treos Bio

TREOS Bio is a clinical-stage biotechnology company developing off-the-shelf and personalized active cancer immunotherapies built on its proprietary PEPI Technology. PEPI Technology is designed to identify "promiscuous epitopes" in a single patient and trigger broad, multi-antigen T-cell responses. The Company's lead programme, PolyPEPI1018, is an off-the-shelf multi-peptide immunotherapy in development for microsatellite-stable colorectal cancer. TREOS Bio is also advancing additional programmes in solid tumors, combining platform-based therapy design with diagnostic strategies intended to identify patients most likely to benefit. For more information, visit www.treosbio.com.

EACR 2026 presentations
https://www.treosbio.com/publications

• Durable pathological complete response associated with broad vaccine-induced T cell immunity in an MSS mCRC patient treated with PolyPEPI1018 peptide vaccine: a case report from the OBERTO-101 study — M. Zhu, E.R. Toke, Zs. Csiszovszki, L. Molnár, J. Tóth, O. Lorincz, E. Somogyi, J. Hubbard.
  
  
• Tumor regression during sequential EGFR-TKI therapy following personalized peptide immunotherapy in EGFR-mutant NSCLC: a translational case report — E. Somogyi, Zs. Csiszovszki, O. Lorincz, L. Molnár, J. Tóth, G. Koppány, K. Pántya, E.R. Toke.
  
  
• Rapid Target Selection for Personalized Cancer Vaccines Using the PEPI Panel Without Tumor Biopsy — O. Lorincz, J. Tóth, L. Molnár, Zs. Csiszovszki, E. Somogyi, K. Pántya, G. Koppány, E.R. Toke.
  
  

For further information, please contact: [email protected]

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