A phase 2 single-arm study of cabozantinib in patients with advanced or unresectable renal cell carcinoma pretreated with one immune checkpoint inhibitor: The BREAKPOINT trial (MeetUro trial 03-NCT03463681).
Authors: Giuseppe Procopio, Melanie Claps, Chiara Pircher, Luca Porcu, Pierangela Sepe, Valentina Guadalupi, Ugo De Giorgi, Cristian Lolli, Marco Maruzzo, Franco Nole, Roberto Iacovelli, Cristina Masini, Cinzia Baldessari, Laura Doni, Antonio Cusmai, Angela Gernone, Sarah Scagliarini, Sandro Pignata, Filippo G. De Braud, Elena Verzoni
Journal: Journal of Clinical Oncology (2021)

4569 Background: For many years, vascular endothelial growth factor (VEGF)-targeted therapy (tp) has been a milestone for metastatic renal cell carcinoma (mRCC). Recently, first line tp based on anti-PD-1/PD-L1 immune-checkpoint inhibitors (ICIs) plus tyrosine-kinase-inhibitors (IO-TKI) and anti-PD-1 plus anti-CTLA-4 combos (IO-IO) significantly improved survival of mRCC patients (pts). Prospective data are lacking to determine the efficacy of anti-VEGF tp after IO-IO or IO-TKI. Cabozantinib (Cabo) showed to prolong survival in mRCC pts pre-treated with TKIs and to target kinases involved in immune-escape. So, it may represent an ideal agent to be used sequentially after ICIs. Methods: This is an open label, single arm, multicenter, phase II study evaluating efficacy and safety of Cabo in mRCC pts who received an anti-PD-1/PD-L1-based adjuvant (adj) or first line tp. Cabo 60 mg/daily was administered until progressive disease (PD) or unacceptable toxicity. Primary endpoint was progression free survival (PFS) by Brookmeyer-Crowley test, secondary endpoints were overall survival (OS), objective response rate (ORR) and safety. Exploratory endopoints were to investigate tissue PD-L1 expression, to assess the modulating activity of Cabo on local and systemic tumor immunity and to explore bone formation and reabsorption markers. Results: From July 2018, 49 pts were enrolled and 48 were included in the analysis. Median age was 62.5 years (range: 30-78), 63% of pts were male. At baseline, 26% of pts had a good Heng risk score, 47% intermediate and 28% a poor risk, while in 2% of pts the class of risk was undetermined. 74% of pts received an IO-IO combo as first line tp, 17% IO-TKI, 9% pts an adj IO monotherapy. Pts received a median of 10 cycles of Cabo (range 5-17 cycles). 25 pts (53%) are still on tp, 1 patient discontinued Cabo for AEs, 13 pts for radiological PD, 6 pts discontinued for clinical PD or death, while 2 pts for reasons other than AEs or PD. Among evaluable cases, 17 pts (43%) achieved a partial response and 15 pts (37%) stable disease. Complete responses were not observed. At a median (m) follow-up of 8.0 months (mo) (4.4-13.5 mo), 71% of pts were alive and mPFS was 9.3 mo (95% CI 7.1-29.0 mo). Grade (G) 3-4 adverse events (AEs) occurred in 34% of pts, including more frequently serum bilirubin increase, hypertension, calcium and sodium serum levels alterations and oral mucositis. G1-2 were observed in 61% of pts, including in most of cases diarrhoea, nausea, oral mucositis, disgeusia, hand-foot syndrome, fatigue and hypothyroidism. Due to AEs, transitory withholding of Cabo was observed in 53.5% of pts and for 23 pts (48%) dose reductions were needed. Conclusions: So far, Cabo tp after IO-IO or IO-TKI showed promising results and was well tolerated. Longer follow-up is needed for final OS and exploratory endpoints results. Clinical trial information: NCT03463681.