Trial results for the Phase 2 study (NCT04171219) investigating pembrolizumab and talabostat for advanced solid cancers were posted on ClinicalTrials.gov on 2025-05-16. This trial was terminated, with median overall survival reported as 16.4 months for treatment-naïve patients and 26.1 months for pretreated patients.
Background
Pembrolizumab (Keytruda) is an immunotherapy that helps the body's immune system attack cancer, with multiple approved indications. Talabostat is an investigational agent that may inhibit tumor cell growth by blocking specific enzymes. This trial investigated the combination of these two agents for the treatment of advanced solid cancers, including both advanced malignant solid neoplasm and recurrent malignant solid neoplasm.
Trial design
The Phase 2 study (NCT04171219) investigated talabostat and pembrolizumab for the treatment of advanced malignant solid neoplasm and recurrent malignant solid neoplasm. The trial enrolled 31 participants and was ultimately terminated. Participants were divided into two cohorts: Cohort A for PD-1/PD-L1 and/or CTLA-4 inhibitor treatment-naïve patients, and Cohort B for PD-1/PD-L1 and/or CTLA-4 inhibitor pretreated patients.
Key results
Results from the terminated trial provided data on disease control rates, dose-limiting toxicities, and survival outcomes across the two cohorts:
- Disease Control Rate Per RECIST v1.1: 4 participants in Cohort A (treatment-naïve) and 4 participants in Cohort B (pretreated) achieved disease control.
- Immune-related Disease Control Rate Per iRECIST: 4 participants in Cohort A and 5 participants in Cohort B achieved immune-related disease control.
- Dose-limiting Toxicities (DLTs): 1 participant in Cohort A experienced DLTs, while 0 participants in Cohort B experienced DLTs.
- Progression-free Survival (PFS) by RECIST v1.1: The median PFS was 2.7 months for Cohort A and 2.5 months for Cohort B.
- Progression-free Survival (PFS) by iRECIST: The median PFS was 2.7 months for Cohort A and 2.5 months for Cohort B.
- Overall Survival (OS): The median OS was 16.4 months for Cohort A and 26.1 months for Cohort B.
What this means
The termination of this Phase 2 trial suggests that the combination of talabostat and pembrolizumab did not meet the predefined criteria for continuation or showed insufficient efficacy to warrant further development in advanced solid cancers. While specific reasons for termination are not detailed in the results, the reported disease control rates and progression-free survival figures are modest. The observed median overall survival, particularly the 26.1 months in the pretreated cohort, provides descriptive data for future research, but the overall context of trial termination limits the immediate clinical implications of these findings.
Source
The information regarding these trial results was obtained from ClinicalTrials.gov, a public database of clinical studies. The results for study NCT04171219, titled "Talabostat and Pembrolizumab for the Treatment of Advanced Solid Cancers," were posted on 2025-05-16 on clinicaltrials.gov.