Ipilimumab challenge/re-challenge in metastatic urothelial carcinoma (mUC) and other genitourinary (GU) tumors treated with cabozantinib+nivolumab (CaboNivo) or cabozantinib+nivolumab+ipilimumab (CaboNivoIpi)

• Published in: Journal of clinical oncology Vol. 38; no. 15_suppl; p. 5039
• Main Authors: Niglio, Scot Anthony, Girardi, Daniel da Motta, Mortazavi, Amir, Lara, Primo, Pal, Sumanta K., Saraiya, Biren, Cordes, Lisa M., Ley, Lisa, Sierra Ortiz, Olena, Cadena, Jacqueline, Diaz, Carlos, Bagheri, Mohammadhadi H., Steinberg, Seth M., Costello, Rene, Streicher, Howard, Wright, John, Parnes, Howard L., Ning, Yang-Min, Bottaro, Donald P., Apolo, Andrea B.
• Format: Journal Article
• Language: English
• Published: 20.05.2020
• ISSN: 0732-183X; 1527-7755
• DOI: 10.1200/JCO.2020.38.15_suppl.5039

Abstract only 5039 Background: We investigated challenging/re-challenging pts with ipilimumab (ipi) after progression on CaboNivo or CaboNivoIpi. Methods: In a phase I expansion study, patients with mUC post-platinum chemotherapy and other GU tumors patients who progressed on Cabo 40 mg daily plus nivolumab, 3 mg/kg every 21 days (CaboNivo) alone or with ipi, 1 mg/kg every 21 days for 4 cycles (CaboNivoIpi)-and achieved a PR or SD≥6 mo, were challenged/re-challenged with ipi, 1 mg/kg every 21 days for up to 4 cycles. Restaging scans were done every 6 wks for the first 12 wks, then every 8 wks and evaluated by RECIST 1.1. Results: In total, 24 patients were evaluated: 18 pts (8 UC (5 bladder and 3 upper tract), 4 clear cell renal cell carcinoma (RCC), 3 urachal adenocarcinoma (adeno), 2 bladder adeno, and 1 sarcomatoid clear cell RCC) who progressed on CaboNivo were challenged with ipi. In the challenge group, median (m) follow-up was 21.2 months. One pt achieved a PR in the LNs, but was found to have brain metastases before the next restaging, 13 had SD and 4 had PD. Median duration of PR or SD was 3.6 months (95% CI: 1.4 – 7.8 months). The mOS from start of ipi challenge was 13.9 months (95% CI: 5.8 months- not estimable); mPFS was 4.6 months (95% CI: 1.9 – 8.7 months). Grade 1/2 treatment related adverse events (AEs) occurred in all 18 pts (100%) and ≥Grade 3 (G≥3) AEs occurred in 11 pts (61%). The most common G≥3 AEs were hypophosphatemia (22%), hypertension (6%), adrenal insufficiency (6%), increased AST (6%), and ALT (6%). Six patients (3 bladder UC, 1 penile squamous cell (SCC) carcinoma, 1 urethral SCC, and 1 clear cell RCC with sarcomatoid features) who progressed on CaboNivoIpi were re-challenged with Ipi. On re-challenge, mfollow-up was 20.9 months. There were no PRs, 3 SDs and 3 PDs. mOS from start of re-challenge was 4.0 months (95% CI: 2.2 – 23.3 months) and mPFS was 1.9 months (95% CI: 1.1 – 2.6 months). Grade 1/2 treatment related AEs occurred in all 6 pts (100%) and ≥Grade 3 (G≥3) AEs occurred in 2pts (33%). G≥3 AEs included 1 hypertension (17%) and 1 hyperphosphatemia (17%). Conclusions: Ipi challenge/re-challenge showed low response rates in pts previously treated with CaboNivo or CaboNivoIpi. However, pts treated with CaboNivo who were challenged with ipi had a better OS than patients who had progressed on CaboNivoIpi and were re-challenged with ipi. Larger trials are warranted testing the ipi challenge in pts progressing on CaboNivo. Clinical trial information: NCT02496208 .