Biotechnology company TILT Biotherapeutics has presented encouraging results for its TILT-123 therapy at the European Society for Medical Oncology (ESMO) Congress 2026.

The company reported on the Phase Ib portion of its PROTA study, which is evaluating TILT-123 (igrelimogene litadenorepvec) in combination with MSD’s anti-PD-1 therapy Keytruda (pembrolizumab) and pegylated liposomal doxorubicin (PLD) in patients with platinum-resistant ovarian cancer.

Platinum-resistant ovarian cancer remains a significant unmet medical need, with limited treatment options available once resistance to platinum-based chemotherapy develops. TILT’s approach aims to enhance anti-tumour immune responses through the use of oncolytic immunotherapy in combination with immune checkpoint inhibition and standard therapies. 

Data presented show that out of 14 patients, nine were evaluable by Response Evaluation Criteria in Solid Tumours (RECIST) version 1.1 at the time of data cut-off. From these, four achieved partial responses, corresponding to an overall response rate (ORR) of 44%. Two patients then covered to complete responses and a third has continued to demonstrate an ongoing response. The fourth responder saw disease progression begin 21 months after initiating treatment.  

Of the remaining five evaluable patients, three achieved stable disease and two had progressive disease, resulting in a disease control rate (DCR) of 78%. Preliminary findings indicate that the triplet combination was well tolerated, with no dose-limiting toxicities identified and no unexpected safety signals observed. 

The study builds on results from the Phase Ia portion of PROTA, which reported encouraging safety findings and preliminary evidence of anti-tumour activity with TILT-123 in combination with pembrolizumab.

Dr Matthew Block, a medical oncologist at the Mayo Clinic and lead investigator of the PROTA trial, said: “We have been struck by both the high frequency of responses to the regimen used in this clinical trial and the durable nature of those responses.  Multiple patients have reported good tolerability of this approach.”

Akseli Hemminki, Founder and CEO of TILT Biotherapeutics, added: “We are encouraged by these results from the Phase Ib portion of the PROTA study. The combination of TILT-123, pembrolizumab and chemotherapy has demonstrated durable responses, along with a favourable safety profile, in a patient population facing limited treatment options. The durability of the responses observed, together with the high disease control rate, further supports our strategy of combining TILT-123 with established immunotherapies and standard-of-care agents to improve outcomes for patients with difficult-to-treat solid tumours.”