Greywolf Therapeutics reports durable clinical responses with first-in-class oral ERAP1 inhibitor GRWD5769 across six solid tumor types

Data from Phase 1b EMITT-1 trial presented in oral session at ASCO 2026 Annual Meeting

• First-in-class oral ERAP1 inhibitor demonstrates objective response rates (ORR) of 13-36% across patients with secondary anti-PD-1 resistance or microsatellite stable colorectal cancer without liver metastases in combination with cemiplimab (anti-PD-1)
  
• Long-lasting responses observed in patients, with multiple patients remaining progression-free for over 6 months across multiple tumor types
  
• Therapy was well tolerated with no safety signals and the trial is ongoing
  

OXFORD, United Kingdom, June 02, 2026 (GLOBE NEWSWIRE) -- Greywolf Therapeutics, a clinical-stage biotech company advancing novel antigen modulation treatments for cancer and autoimmune diseases, today reports clinical and translational results from six completed Phase 1b expansion cohorts of the EMITT-1 trial (NCT06923761) evaluating GRWD5769, a first-in-class oral ERAP1 inhibitor, in combination with cemiplimab in patients with secondary anti-PD-1 resistance or microsatellite stable colorectal cancer without liver metastases (MSS-CRC NLM).

Data were presented in an oral session at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting by Professor Fiona Thistlethwaite, Consultant Medical Oncologist at The Christie NHS Foundation Trust and Medical Director of the National Institute for Health and Care Research (NIHR) Manchester Clinical Research Facility at The Christie, and Principal Investigator of the EMITT-1 trial.

Professor Fiona Thistlethwaite, Consultant Medical Oncologist at The Christie NHS Foundation Trust and Medical Director of the National Institute for Health and Care Research (NIHR) Manchester Clinical Research Facility at The Christie said:

"What excites me about this trial is the combination of what we're seeing - strong signals of efficacy across six tumor types that have shown great resistance to immunotherapy, with very few side effects. That's unusual at such an early stage."

Highlights from the Phase 1b data

• Objective Response Rates (ORR) of 13-36% across all six cohorts in patients with a median of 2 prior lines of therapy and documented secondary anti-PD-1 resistance (except MSS-CRC (NLM) where this therapy is not effective)
  
• Durable Clinical Benefit of 18-55% across all cohorts (DCB - defined as complete response, partial response, or stable disease lasting =6 months) and Progression Free Survival duration of 33 wks in NSCLC, 16 wks in HCC and 33 wks in MSS-CRC (NLM) (with 8.8 months median follow-up and still maturing). These data are very encouraging in a setting where durable benefit is exceptionally rare.
  
• GRWD5769 is well tolerated in cemiplimab combination, with no safety signals and most adverse events being Grade 1
  

	Evaluable* (n)	Partial response(s)	Overall response rate (%)	Durable clinical benefit (%)	Progression-free survival (wks)
Urothelial carcinoma	14	5	36	36	8
Non-small cell lung cancer	14	3	21	55	33
Hepatocellular carcinoma (liver cancer)	14	2	14	32	16
Microsatellite stable colorectal cancer (no liver metastases)	12	2	17	51	33
Cervical	14	2	14	18	9
Head and neck squamous cell carcinoma	8	1	13	38	14

Tom Lillie, Chief Medical Officer of Greywolf Therapeutics, said:

"Seeing the combination of strong durable clinical benefit rates and sustained PFS in a population that had already failed anti-PD-1 therapy, and in MSS-CRC where it isn't licensed, is a clinically meaningful signal. Critically, we're seeing this alongside a tolerability profile that enables patients to remain on treatment for extended periods, providing excellent potential for GRWD5769 to be used in other combination therapies."

Peter Joyce, CEO and Co-founder of Greywolf Therapeutics, said:

"EMITT-1 has validated a mechanism that the field has long recognized as scientifically compelling but clinically unproven. We are now advancing into Stage 2 cohort expansions to inform a randomized Phase 2 study, and we believe this data positions GRWD5769 as a genuinely differentiated approach to two of the largest unmet needs in oncology - T cell exhaustion and tumor visibility to the immune system."

About GRWD5769

GRWD5769 is a first-in-class oral small molecule inhibitor of Endoplasmic Reticulum Aminopeptidase 1 (ERAP1), an enzyme that regulates tumor antigen presentation on MHC-I. By inhibiting ERAP1 on a cyclical Q3W on/off schedule, GRWD5769 aims to generate alternating antigenic repertoires to broaden T cell responses and prevent T cell exhaustion driven by chronic antigen exposure. The drug is administered as an oral capsule in combination with cemiplimab, an approved anti-PD-1 therapy.

About the EMITT-1 trial

EMITT-1 (NCT06923761) is a global Phase 1/2 study evaluating GRWD5769 in combination with cemiplimab across multiple solid tumor types. The Phase 1b expansion enrolled patients across six cohorts: non-small cell lung cancer (NSCLC), urothelial carcinoma (UC), hepatocellular carcinoma (HCC), MSS-CRC (without liver metastases), squamous cell carcinoma of the head and neck (SCCHN), and cervical cancer. All patients had secondary resistance to prior anti-PD-1 therapy, except for the MSS-CRC NLM cohort. The trial is ongoing across 28 centers in Australia, France, Spain, and the United Kingdom.

About Greywolf Therapeutics

Greywolf Therapeutics is a clinical-stage biotech company advancing novel antigen modulation treatments for cancer and autoimmune diseases.

The company's first-in-class small molecules are developed to control T cell activation by modulating antigen presentation, altering how cells appear to the immune system so it can recognize and target them correctly.

Greywolf is headquartered in Oxford, UK.

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