Abstract 7523: An integrated analysis of radiologic and pathological responses in patients with metastatic renal cell carcinoma who presented with primary renal tumor in situ and received first-line nivolumab plus ipilimumab followed by cytoreductive nephrectomy
Authors: Clemente Leticia Campos , Alhalabi Omar , Campbell Matthew T. , Alonso Guillermo Corredor , Hara Kieko , Msaouel Pavlos , Johns Andrew C. , Tang Chad , Karam Jose A. , Rao Priya , Tannir Nizar M. 
Published: March 2024

Abstract
Background: The decision to perform cytoreductive nephrectomy (CN) and timing of CN in patients (pts) with metastatic renal cell carcinoma (mRCC) and primary who respond to immune checkpoint therapy (ICT) is a matter of debate. In CheckMate-214, nivolumab plus ipilimumab (N+I) yielded a 35% objective response rate in the primary; however, there is a paucity of pathological data from nephrectomy specimens (Nx) after treatment with N+I. We sought to investigate the radiologic and pathological responses and correlate the findings with outcomes in pts receiving 1L N+I followed by CN.
Methods: We reviewed the medical records and Nx of pts with mRCC who received N+I followed by CN at our institution (2016-2021). H&E slides were reviewed to determine the % of residual viable malignant cells. Pathological response was defined as tumor viability ≤20%, and pathological complete response (pCR) defined as absence of residual cancer. Radiologic response was defined as ≥30% reduction in primary size. Progression-free survival (PFS) and overall survival (OS) were determined from date of CN.
Results: 22 pts (median age 59) are included: 18 (81.8%) males, 19 (86%) Caucasian, 20 (91%) had clear-cell histology, 20 (91%) had ECOG Performance Status 0-1, 10 (45%) had intermediate-risk disease and 12 (55%) had poor-risk disease by IMDC. Median ICT duration before CN was 6.5 months (mo) (range, 2-19 mo). 17 (77%) completed 4 cycles of N+I, and 16 (73%) received N maintenance before CN. 5 pts (23%) had grade 3/4 immune-related adverse effects; 1 pt did not complete 4 cycles of N+I due to hepatitis. There were no therapy-related deaths. 12 pts (54.5%) had progressive disease (PD); 3 pts (14%) died of RCC. Median PFS was 22 mo, median OS not reached (NR). Pts with pathological response had greater radiologic reduction in primary size compared to pts without pathological response (median reduction 38% vs. 15% p-value 0.01), smaller final primary pathological size (median 5.7 cm vs. 10.65 cm p-value 0.002), and lower pathological yT stage (pT0: 1, pT1: 6, pT2: 2 pT3: 3, pT4: 0 vs. pT0: 0, pT1: 1, pT2: 0, pT3: 8, pT4: 1 p-value 0.045); ICT duration was similar between groups (median 5.5 mo vs. 7 mo p-value 0.733). 6 pts achieved low viability within 5 mo of ICT. In 9 pts with optimal radiopathological response [viability ≤20% and ≥30% primary size reduction], PFS was longer compared to PFS in pts with suboptimal radiopathological response: median PFS NR vs. 17 months (HR 0.23, 95% CI 0.076 - 0.741; p-value 0.041). In 13 pts with suboptimal response, 10 (77%) had PD, the most common sites of PD were lymph nodes [6 pts (60%)] and brain [3 pts (30%)].
Conclusions: In this small cohort, N+I yielded a low pCR in Nx of pts with mRCC. Radiologic response but not ICT duration was associated with low tumor viability.
Citation Format: Leticia Campos Clemente, Omar Alhalabi, Matthew T. Campbell, Guillermo Corredor Alonso, Kieko Hara, Pavlos Msaouel, Andrew C. Johns, Chad Tang, Jose A. Karam, Priya Rao, Nizar M. Tannir. An integrated analysis of radiologic and pathological responses in patients with metastatic renal cell carcinoma who presented with primary renal tumor in situ and received first-line nivolumab plus ipilimumab followed by cytoreductive nephrectomy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7523.