TILT Biotherapeutics Presents Encouraging Phase 1b Results in Ovarian Cancer at ESMO 2026
Four of nine evaluable patients responded to TILT-123 combined with pembrolizumab and pegylated liposomal doxorubicin,
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HELSINKI, Finland, Oct. 26, 2026 (GLOBE NEWSWIRE) — TILT Biotherapeutics (TILT), a clinical-stage biotechnology company developing intravenously delivered cancer immunotherapies, today announces preliminary safety and efficacy results from the Phase 1b portion of its PROTA study (NCT05271318) presented at the European Society for Medical Oncology (ESMO) Congress 2026.
The trial evaluated TILT-123 (igrelimogene litadenorepvec) in combination with MSD’s (Merck & Co., Inc., Rahway, NJ, USA) anti-PD-1 therapy KEYTRUDA® (pembrolizumab) and pegylated liposomal doxorubicin (PLD) in patients with platinum-resistant ovarian cancer.
Out of fourteen patients treated, nine were evaluable by Response Evaluation Criteria in Solid Tumours (RECIST) version 1.1 at the time of data cut-off, four achieved confirmed partial responses, corresponding to an overall response rate (ORR) of 44%. Notably, two of these patients subsequently converted to complete responses, while a third continued to demonstrate an ongoing response that had been maintained for 12 months at the time of analysis. The fourth responder experienced disease progression 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.
Dr Matthew S. Block, MD, PhD, a medical oncologist at the Mayo Clinic and lead investigator of the PROTA trial, commented on the data: “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.”
Patient enrolment into the Phase 1b study was completed in January 2026. Several patients continued into an extended treatment period following the initial treatment phase, with some still receiving therapy because of ongoing clinical benefit. The study builds on results from the Phase 1a portion of PROTA, which reported encouraging safety findings and preliminary evidence of anti-tumour activity with TILT-123 in combination with pembrolizumab.
Akseli Hemminki, Founder and CEO of TILT Biotherapeutics, said: “We are encouraged by these results from the Phase 1b 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.”
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. The Company believes these encouraging findings continue to support the development of TILT-123 in solid tumours.
The study design and key efficacy and safety findings are presented in the ESMO 2026 Poster #1281P: “Phase 1b study of igrelimogene litadenorepvec plus pembrolizumab and pegylated liposomal doxorubicin in platinum-resistant ovarian cancer: preliminary safety and efficacy results.”
KEYTRUDA® is a registered trademark of Merck Sharp & Dohme LLC, a subsidiary of Merck & Co., Inc., Rahway, NJ, USA.
Notes to Editors
About TILT Biotherapeutics
TILT Biotherapeutics is developing intravenously delivered cancer immunotherapies.
TILT’s approach uses oncolytic viruses to selectively replicate in and lyse cancer cells while simultaneously stimulating immune responses towards the tumour.
TILT-123 (igrelimogene litadenorepvec) is a clinical-stage oncolytic adenovirus armed with tumour necrosis factor (TNF) and interleukin-2 (IL-2), designed to enhance the efficacy of T-cell therapies and immune checkpoint blockade. Approximately 100 patients have been treated in five international clinical trials with favourable safety profiles and preliminary evidence of anti-tumour activity.
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