Trial results for a Phase 2 study (NCT03752333) investigating pembrolizumab in patients with cancer of unknown primary site were posted on ClinicalTrials.gov on 2026-05-04. The study enrolled 35 participants across two cohorts.
Background
Pembrolizumab (Keytruda) is an immunotherapy drug. This trial investigated its use in patients with cancer of unknown primary site (CUP).
Trial design
The study, identified as NCT03752333, was a Phase 2, single-arm, non-randomized, two-stage trial. It enrolled 35 participants with cancer of unknown primary site. The trial investigated pembrolizumab as an intervention. Participants were divided into two cohorts: one with one or more lines of prior therapy, and another with first-line untreated CUP patients. The study was hypothesis-generating and did not include a control arm.
Key results
The trial reported participant counts related to overall response rate and adverse events:
- For the outcome "Overall Response Rate (ORR) by RECIST Criteria v1.1 in the Second-line & First-line Setting," the following participant counts were reported for the Pembrolizumab group: 0, 4, 9, 13, and 9 participants.
- Regarding "Incidence Proportion of Adverse Events up to 8 Weeks After the Last Dose of Pembrolizumab in the Second Line Setting," 34 participants were reported.
- For "Incidence of Adverse Events up to 8 Weeks After the Last Dose of Pembrolizumab in Performance Status 2 (PS2) Patients in Any Setting," 5 participants were reported.
What this means
The posted results provide initial participant counts related to overall response and adverse events in a Phase 2 study of pembrolizumab for cancer of unknown primary site. Without further context, such as specific response rates, statistical analyses, or detailed adverse event profiles, the practical implications of these counts for clinical practice remain to be fully understood. This single-arm, hypothesis-generating trial contributes to the ongoing research into potential treatments for this challenging condition.
Source
The information regarding these trial results was obtained from ClinicalTrials.gov, a public database of clinical studies. The results for study NCT03752333, titled "Trial of Pembrolizumab in Cancer of Unknown Primary," were posted on 2026-05-04 on clinicaltrials.gov.