Neoadjuvant nivolumab (N) + ipilimumab (I) in cisplatin-ineligible patients with upper tract urothelial cancer (UTUC): Updated results.

Abstract

645 Background: Perioperative platinum-based chemotherapy for UTUC improves pathologic responses and disease-free survival (DFS). We report the updated results from our on-going phase II neoadjuvant trial of N+I for cisplatin-ineligible patients (pts) with UTUC (NCT03520491). Methods: Cisplatin-ineligible pts with histologically confirmed high-grade UTUC and/or radiographically invasive UTUC with positive selective urine cytology were eligible. Pts were treated with I 3mg/kg + N 1mg/kg (weeks 0, 6), and “N” 3mg/kg (week 3) prior to radical nephroureterectomy (NU). The primary endpoint (EP) was pathologic complete response (pCR, ypT0pN0) and secondary EPs included <ypT2pN0 rate, DFS, and toxicity. Next generation sequencing of pre-treatment tumors was correlated with pathologic response. Results: Seventeen pts (76% male) were enrolled between 2/2021-6/2023 with median age 73 (range 59-85). Primary sites included ureter in 10 pts, renal pelvis in 5 and both in 2. Median tumor diameter was 3.0 cm, (range: 1.5 - 4.2 cm), with 8 pts (47%) having hydronephrosis. To date, 11 pts (65%) have received all planned treatment, 6 pts had N+/-I stopped early due to treatment-related toxicities, 2 pts are pending NU, 13 pts have undergone NU, 1 declined surgery, and another progressed on N+I. A pCR was seen in 4/15 pts (27%) and <ypT2pN0 in 9/15 (60%). Median time from last treatment to NU was 1.6 months (range 0.5-4.9). Three pts developed metastatic recurrence at 3.9, 10.3 and 15.6 months after treatment initiation. CTCAE grade ≥3 treatment-related adverse events occurred in 5 pts (29%). Four pts died during follow up: two of metastatic disease, one of complications related to a bowel leak (7.2 months after N+I initiation and 4.7 months after NU), and one from complications of a fall unrelated to disease or treatment (9.2 months after N+I initiation and 4.7 months after NU). Median tumor mutational burden (TMB) in 9 pts with pre-treatment sequencing was 13.2 mutations/mb (range 4.1-106.3), with 4/5 pts with TMB>10 <ypT2pN0 at NU. Pathogenic germline variants in mismatch repair genes were confirmed in 4 pts (MSH2 in 3, MLH1 in 1) and MSI-high tumors without germline alterations in 2 pts, with 5 of 6 completing NU (1 pending surgery); all 5 achieved pCR (n=3) or ypTaN0 (n=2) and remain alive and disease-free at last follow-up (6, 13.4, 17, 17.9 and 31 months). Conclusions: Updated findings from an on-going phase II trial of cisplatin-ineligible pts with UTUC receiving neoadjuvant N+I shows clinical activity in line with our initial results. All pts with pathogenic germline variants in mismatch repair genes or MSI-high tumors without germline alteration who underwent NU achieved <ypT2pN0 and remain free of disease. Clinical trial information: NCT03520491 .