Trial results for the Phase 1b/2a study (NCT05383170) investigating CyPep-1 in combination with pembrolizumab (Keytruda) for advanced or metastatic cancers were posted on ClinicalTrials.gov on 2025-11-28. The Phase 1b portion of the study reported a median progression-free survival (PFS) of 3.3 months and a median overall survival (OS) of 13.4 months in patients with advanced cancers.
Background
Pembrolizumab (Keytruda) is an anti-PD-1 antibody. This study investigated CyPep-1 in combination with pembrolizumab for the treatment of advanced or metastatic cancers, specifically including advanced head and neck squamous cell carcinoma, advanced breast cancer, and advanced melanoma.
Trial design
The study (NCT05383170) was a Phase 1b/2a trial, with the reported results pertaining to the Phase 1b portion. It enrolled 6 participants with advanced or metastatic cancers, including advanced head and neck squamous cell carcinoma, advanced breast cancer, and advanced melanoma. The trial assessed CyPep-1 administered directly into measurable tumor lesions in combination with pembrolizumab.
Key results
The Phase 1b portion of the trial focused on evaluating safety and preliminary efficacy. Key safety results included:
- The frequency of treatment-emergent adverse events (TEAEs) was reported as 11, 19, 2, 0, and 0 events across different categories.
- The incidence of dose-limiting toxicities (DLTs) was reported as 1 event.
Regarding efficacy, the study reported:
- Median progression-free survival (PFS) per RECIST v1.1 was 3.3 months.
- Median overall survival (OS) per RECIST v1.1 was 13.4 months.
What this means
The results from this Phase 1b study provide initial safety and efficacy data for the combination of CyPep-1 with pembrolizumab in a small cohort of patients with advanced or metastatic cancers. The observed median PFS of 3.3 months and OS of 13.4 months offer preliminary insights into the potential anti-tumor activity of this combination. The safety profile, including the reported frequency of TEAEs and the incidence of 1 DLT, will inform further development of this therapeutic approach. These early-phase findings warrant further investigation in larger clinical trials.
Source
The information for these trial results was obtained from ClinicalTrials.gov, a public database of clinical studies. The results for study NCT05383170, titled "A Study to Evaluate the Safety and Efficacy of CyPep-1 in Combination With Pembrolizumab for the Treatment of Advanced or Metastatic Cancers," were posted on 2025-11-28 on clinicaltrials.gov.