Pembrolizumab for Locally Advanced or Metastatic Urothelial Cancer Where Cisplatin is Unsuitable: An Evidence Review Group Perspective of a NICE Single Technology Appraisal

Abstract

As part of its Single Technology Appraisal (STA) process, the National Institute for Health and Care Excellence (NICE) invited the manufacturer (Merck Sharp & Dohme) of pembrolizumab (Keytruda^®) to submit evidence of its clinical and cost effectiveness for the treatment of locally advanced or metastatic urothelial cancer where cisplatin is unsuitable. The School of Health and Related Research Technology Appraisal Group at the University of Sheffield was commissioned to act as the independent Evidence Review Group (ERG). The ERG produced a detailed review of the evidence for the clinical and cost effectiveness of the technology, based on the company’s submission (CS) to NICE. The clinical effectiveness evidence in the CS for pembrolizumab was based on one phase II, single-arm, open-label, non-randomised study (KEYNOTE-052), while the evidence for the comparator (carboplatin plus gemcitabine) was based on four studies, including one randomised controlled trial and three cohort studies. In the absence of head-to-head trials, the company conducted an indirect treatment comparison for both progression-free survival (PFS) and overall survival (OS), by firstly adjusting cross-study differences using a simulated treatment comparison approach and then synthesizing the evidence based on an assumption of constant hazard ratios using a standard meta-analysis model and time-varying hazard ratios using fractional polynomial models. The treatment effect of pembrolizumab was more favourable in the adjusted population compared with the observed effect in the KEYNOTE-052 study. The company submitted a de novo partitioned survival cohort simulation model, which partitions the OS time into PFS and post-progression survival. The probabilistic incremental cost-effectiveness ratio (ICER) for pembrolizumab compared with carboplatin plus gemcitabine was estimated to be £37,081 per quality-adjusted life-year (QALY) gained, based on the results within the company’s health economic model. Following a critique of the model, for their preferred base case the ERG corrected some minor model errors, chose a progression approach for estimating utilities, and revised the extrapolation of PFS and OS. The ERG’s probabilistic base case ICER was estimated to be £67,068 per QALY gained. The ERG also undertook a range of exploratory sensitivity analyses which suggested that the ICER was highly uncertain. In particular, the choices of extrapolation for the OS of pembrolizumab and the stop** rule for pembrolizumab had the largest impacts on the ICER. The NICE Appraisal Committee recommended pembrolizumab for use within the Cancer Drugs Fund as an option for treating locally advanced or metastatic urothelial carcinoma in adults who have had platinum-containing chemotherapy, provided that pembrolizumab was stopped at 2 years of uninterrupted treatment, or earlier if the disease progresses, and the conditions of the managed access agreement for pembrolizumab are followed.