The combination of rintatolimod (Ampligen) plus pembrolizumab (Keytruda) and cisplatin produced an objective response rate (ORR) of 50% in patients with recurrent, platinum-sensitive ovarian cancer, meeting the primary end point of a phase 2 study (NCT03734692) being led by the University of Pittsburgh Medical Center.1,2
In addition, the regimen led to a complete response rate of 21% and partial response rate of 29%. The clinical benefit rate was 79%, with some responses lasting more than 70 months in select patients. The median overall survival (OS) was 32.5 months, and the median progression-free survival (PFS) was 8.3 months. With respect to safety, no grade 4 or 5 adverse effects (AEs) were reported.
“This single-arm phase 2 trial is the third in a series of consecutive studies evaluating [intraperitoneal] IP chemotherapy or chemoimmunotherapy using this analytical approach. The addition of IP [rintatolimod] and systemic PD-1 checkpoint inhibition to IP cisplatin chemotherapy resulted in a significant improvement in both clinical response rates and immune activation across highly comparable patient cohorts in the 3 trials,” Robert P. Edwards, MD, McCall Chair of Obstetrics, Gynecology, and Reproductive Science at the University of Pittsburgh School of Medicine in Pennsylvania, stated in a news release.1
Data regarding other secondary end points such as PFS, time to disease progression, and OS are anticipated by January 2027.
“These results represent what we believe is a strong step forward in the potential to enhance treatment of recurrent ovarian cancer, if further studies support findings of relatively low toxicity, clinical benefit and durable response,” Thomas K. Equels, MS, JD, chief executive officer, president, and executive vice chairman of AIM, added the news release. “Once again, data suggests that [rintatolimod] may unlock the full potential of checkpoint immunotherapies. We are particularly encouraged by the durability of the observed responses.”
Phase 2 Trial Shows Promising Results for Rintatolimod Combo in Recurrent Ovarian Cancer
- The combination of rintatolimod, pembrolizumab, and cisplatin displayed a 50% objective response rate and 79% clinical benefit rate in recurrent platinum-sensitive ovarian cancer.
- Patients experienced durable responses, with some remaining disease-free for more than 70 months; median overall survival reached 32.5 months.
- Treatment was associated with a manageable safety profile, with no grade 4 or 5 adverse effects reported in the phase 2 study.
What is rintatolimod and how was it used in the phase 2 trial?
Rintatolimod is a first-in-class dsRNA and highly selective TLR3 agonist immuno-modulator with broad spectrum activity in cancers, viral diseases, and autoimmune disorders.
The agent was studied in combination with chemoimmunotherapy in an investigator-initiated, single-arm phase 2 trial that was conducted from 2017 to 2025.2 To be eligible for inclusion patients had to have experienced their first or second recurrence of platinum-sensitive ovarian or fallopian tube cancer with measurable peritoneal or retroperitoneal lesions.
How was the combination treatment administered?
All patients received six 3-week cycles of IP cisplatin at a dose of 50 mg/m², followed by sequential administration of 200 mg of intravenous pembrolizumab and 200 mg of IP rintatolimod. Treatment continued until progression, toxicity, or patient/provider decision.
The primary end point was 13-week ORR per RECIST 1.1 criteria. Secondary end points included changes in tumor-infiltrating CD8-positive T cells, safety, and AEs.
A total of 3 of the 27 enrolled patients were not evaluable for response. The median age was 68 years old (range, 51-79). Most patients (68%) had high-grade serous histology and were experiencing their first recurrence (64%). Slightly less than half the population (44%) had completed all 6 intended cycles of treatment.
When the results were released, 50% of patients had died, with the rest either disease-free or in ongoing treatment.
What safety findings were reported?
The specific AEs included fatigue (100%), anemia (79%), abdominal pain (67%), and nausea (83%). Three patients experienced immune-related AEs which led to trial discontinuation; off study, 2 of these patients remain disease-free for more than 70 months.
What could these findings mean for the future of immunotherapy in ovarian cancer?
“This supports our proposition that [rintatolimod] has the potential to play a major role in solid tumor immuno-oncology – expanding the number of patients who benefit from checkpoint inhibitors across multiple cancer types, including ovarian cancer and pancreatic cancer. With strong intellectual property protection extending into 2039 and a growing body of positive clinical evidence, we believe we are well positioned to advance [rintatolimod] into later-stage development and strategic partnerships,” Equels concluded in the news release.1
References
- AIM ImmunoTech announces 50% objective response rate (ORR) in UPMC recurrent ovarian cancer phase 2 clinical trial, suggesting breakthrough combination potential. News release. AIM ImmunoTech Inc. May 7, 2026. Accessed May 14, 2026. https://aimimmuno.com/aim-immunotech-announces-50-objective-response-rate-orr-in-upmc-recurrent-ovarian-cancer-phase-2-clinical-trial-suggesting-breakthrough-combination-potential/
- NCT03734692: systemic immune checkpoint blockade and intraperitoneal chemo-immunotherapy in recurrent ovarian cancer. News release. Magee-Women’s Hospital of UPMC Cancer Centers. Accessed May 14, 2026. https://s3.amazonaws.com/b2icontent.irpass.cc/2265/200115.pdf
