Real-world outcomes in patients with metastatic renal cell carcinoma (mRCC) receiving dual immune checkpoint inhibitor (ICI-ICI) regimens or immune checkpoint inhibitor and tyrosine kinase inhibitor (ICI-TKI) combinations as first-line therapy: A British Columbia (BC) population-based analysis.

Abstract

646 Background: Currently available first-line treatment regimens for mRCC include pembrolizumab-axitinib (ICI-TKI) and ipilimumab-nivolumab (ICI-ICI). Although both regimens are superior to sunitinib, direct comparisons between ICI-ICI and ICI-TKI are lacking and real-world data are sparse. Methods: Through BC Cancer pharmacy data and patient access programs queries, we identified 319 mRCC patients who were treated with first line ICI-TKI or ICI-ICI between May 2019 and March 2022. Patients’ charts were reviewed for baseline characteristics, including International mRCC Database Consortium (IMDC) risk criteria, pharmacy data, pathology and radiology reports, treatment toxicity, rationale for treatment choice when available, progression and survival outcomes. Treatment groups were compared using standard descriptive statistics; survival outcomes were compared using Kaplan Meier and Cox Regression analyses. Results: Among the first 214 patients, 64.9% and 35.1% received first line ICI-ICI and ICI-TKI, respectively. The most commonly cited reason for choosing ICI-ICI was unavailability of a publicly funded alternative at the time of prescription. IMDC risk group distribution was markedly different between regimens; in ICI-TKI patients, favorable, intermediate and poor-risk patients respectively represented 60.3%, 28.8% and 10.9%, versus 10.2%, 56.9% and 32.9% in ICI-ICI patients (p<0.001). Response rates in ICI-TKI compared favorably to ICI-ICI in the overall population with objective response rates (ORR) of 69% vs 50.4% (p=0.012) and primary progression rates of 12.7% vs 33.1% (p=0.001). However, in the intermediate-poor risk patients, survival outcomes were similar between ICI-TKI and ICI-ICI, with median progression-free survival (mPFS) of 7.5 versus 4.5 months respectively (hazard ratio [HR] 0.67, 95% confidence interval [CI] 0.41 to 1.09, p=0.107) and median overall survival (mOS) of not reached (NR) vs 22.6 months (HR 0.86, 95% CI 0.44 to 1.69, p=0.665). Of interest, in patients treated with ICI-ICI, more ipilimumab infusions in the induction phase was associated with improved mOS, rising from 3.9 to 13.6, 21.8 and 37.5 months for 1, 2, 3 or 4 infusions respectively (statistically significant by Log Rank [Mantel-Cox], p<0.001). Conclusions: In the real-world mRCC experience from BC, Canada, ICI-TKI was associated with statistically significantly improved ORR over ICI-ICI although the treated population was comparatively enriched for favorable risk patients by IMDC. PFS and OS did not differ between the two regimens in the intermediate-poor risk population. Updated results on all 319 patients will be presented.