Pembrolizumab shows benefit in heavily pretreated mCRPC

  • Tucker MD & al.
  • Cancer Med
  • 3 Jul 2019

  • curated by Deepa Koli
  • Univadis Clinical Summaries
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Takeaway

  • Pembrolizumab showed ≥50% confirmed PSA decline in 17% of patients with heavily treated metastatic castrate-resistant prostate cancer (mCRPC).
  • 75% of men who harbor pathogenic LRP1b mutations had ≥50% confirmed PSA decline.

Why this matters

  • LRP1b mutations is a potential marker for pembrolizumab response in mCRPC.

Study design

  • Study of 48 patients with heavily treated mCRPC who received ≥1 cycle of pembrolizumab.
  • Funding: No external funding.

Key results

  • 94% of patients received ≥3 prior treatment lines.
  • 52% of patients received concurrent therapy with pembrolizumab.
  • 21% of patients reported confirmed ≥30%, 17% had ≥50%, and 8% had confirmed ≥90% PSA decline.
  • Of 23 patients who received concurrent enzalutamide, 22% reported ≥50% PSA decline.
  • Median PSA-PFS was 1.8 months.
  • In 38% of patients with evaluable somatic genomic profiling:
    • Most common alterations: TMPRSS2-ERG fusion (33%), PTEN loss (28%), and AR amplifications (22%).
    • 4 patients had LRP1b mutation, and 75% of these reported ≥50% PSA decline.
  • Adverse event (AE) rate was 35%; 3 grade 3 AEs were reported.

Limitations

  • Retrospective design and small sample size.