ClinicalTrials.gov posted trial results on 3 September 2026 for a completed study of pembrolizumab in advanced cancer. The Phase 1/2 study enrolled 323 participants and evaluated FLX475, also called tivumecirnon, alone and in combination with pembrolizumab.

Background

The study examined tivumecirnon monotherapy and tivumecirnon with pembrolizumab, also known by the brand name Keytruda. Its stated purpose was to assess safety and preliminary anti-tumor activity in people with advanced cancer. The interventions listed in the registry were tivumecirnon and pembrolizumab.

Trial design

This was an open-label, sequential-group, dose-escalation and cohort-expansion study identified as NCT03674567. It had a Phase 1/Phase 2 design and was listed as completed, with 323 participants enrolled.

The trial had two parts. Part 1 used sequential dose-escalation cohorts of tivumecirnon as monotherapy or in combination with pembrolizumab. Part 2 used cohort expansion. The primary outcome concerned safety and tolerability, including adverse events, dose-limiting toxicities, and maximum tolerated dose. No primary outcome entries or statistical analyses were supplied in the data.

Key results

The posted measurements reported participant counts for dose-escalation and expansion groups under the safety and tolerability outcome:

  • Tivumecirnon monotherapy at 25 mg: 2 participants; 50 mg: 3 participants; 75 mg: 6 participants; 100 mg: 6 participants.
  • Tivumecirnon with pembrolizumab at 50 mg: 3 participants; 75 mg: 2 participants; 100 mg: 8 participants.
  • Expansion monotherapy cohorts M1 through M5 included 8, 14, 10, 9, and 12 participants, respectively.

The supplied record did not include adverse-event totals, dose-limiting-toxicity results, a maximum tolerated dose, response measurements, p-values, confidence intervals, or comparative analyses.

What this means

The record documents completion and the availability of measurements from a dose-escalation and cohort-expansion study of tivumecirnon with or without pembrolizumab in advanced cancer. The reported figures describe the sizes of selected treatment groups, not treatment benefit or comparative safety.

Because the supplied data do not report outcome analyses or an adverse-event summary, they do not establish whether the regimen demonstrated anti-tumor activity, identified a maximum tolerated dose, or changed pembrolizumab’s approved use.

Source

Source: ClinicalTrials.gov, registry record for “Dose Escalation and Expansion Study of FLX475 Monotherapy and in Combination With Pembrolizumab,” NCT03674567, with results posted on 3 September 2026. The record is available at clinicaltrials.gov/study/NCT03674567.