Background: Immune checkpoint combination therapy (ICI-combo) is the new standard of care for mRCC in first-line setting. However, pts with poor PS (≥2) were excluded from pivotal trials. Hence, the activity and safety of ICI-combo in this group of pts is still unknown. Methods: We performed a multicentre retrospective study of PS≥2 mRCC pts who received ICI-combo, either nivolumab-ipilimumab (NI) or pembrolizumab-axitinib (PA) as first-line treatment between 2017-2021. Patient’s characteristics, clinical outcomes and toxicity were retrospectively reviewed. We analysed overall response rate (ORR), disease control rate (DCR), progression-free survival (PFS), overall survival (OS) and grade ≥3 treatment-related adverse events (G≥3 AEs) in pts treated with NI or PA. The association between LIPI (Lung Immune Prognostic Index) and ORR, PFS and OS was also evaluated. Results: We identified 56 mRCC pts with PS≥2 treated with ICI-combo across 13 institutions. Thirty-six and 20 pts were treated with NI and PA respectively. Median age at diagnosis was 64 (31-83) years, 38 (68%) were male, 16 (29%) had prior nephrectomy and 40 (71%) had synchronous metastatic disease at diagnosis. Respectively, 19 (34%) and 37 (66%) pts were intermediate and poor risk according to IMDC. Fifty pts (89%) were clear cell RCC, and only 4 pts had sarcomatoid features reported. At the time of analysis (median follow-up 11.1 months(mo)) 45% pts were dead. The ORR for the entire cohort was 27%; ORR was numerically higher with PA (42%) than with NI (20%) but did not reach statistical significancy (p=0.157). Median PFS (mPFS) and mOS in the entire cohort were 4.4 mo and 15.9 mo respectively. No significant differences in PFS, OS or the rate of G≥3AEs were seen between the NI and PA groups. Efficacy and toxicity outcomes are described in the table below. No significant differences in OS or PFS according to the IMDC risk score were observed (p=0.818). However, LIPI was significantly associated with OS (poor LIPI: HR=8.18; p=0.004) and PFS (Intermediate LIPI: HR=2.4; p=0.048 and poor LIPI: HR=8.59; p<0.001). LIPI was predictive of response in patients treated with NI (p=0.024). Conclusions: We report the first cohort of PS≥2 mRCC pts treated with ICI-combo in first-line setting. No significant differences in ORR, PFS or OS were seen between NI and PA. LIPI was significantly associated with both OS and PFS, and was predictive of ORR in the NI group. Prospective real-world studies are needed to confirm these results.

*19/20 evaluable for response; # 35/36 evaluable for response.