Singla, Nirmish

Abstract GPNMB (Glycoprotein non-metastatic melanoma protein B) is a canonical transcriptional target of MiT/TFE proteins (TFEB/TFE3/MITF), expressed at low levels in normal tissues but upregulated in numerous MiT/TFE-driven tumors such as translocation RCC, alveolar soft part sarcoma and MITF-driven melanoma, where it is associated with poor prognosis. CDX-011 (CR011-MMAE) is an anti-GPNMB ADC, with demonstrated efficacy in pre-clinical models of TFE3-fusion RCC. To further characterize GPNMB functionality and value as a cell-surface therapeutic target in tRCC, we engineered cell lines with genomic deletion of GPNMB via CRSIPR-Cas9 editing. Deletion of GPNMB in PRCC-TFE3 cell lines [UOK120/UOK124] significantly decreased clonogenic growth in 2D, spheroid size and viability and tumor xenograft growth in NSG mice and was associated with a decrease in phosphorylation of mTORC1 substrates [p-P70S6K, p-4EBP1]. We then examined expression of CD44, the primary receptor for GPNMB, and a tumor-associated antigen associated with poor prognosis in many cancers. Expression of CD44 and its ligand SPP1/OPN, was significantly increased in bulk RNA-Seq data from multiple transgenic models of SFPQ-TFE3, PRCC-TFE3 and ASPSCR1-TFE3, in human tRCC cases compared to normal kidney, and in SFPQ-TFE3/ PRCC-TFE3 transgenic kidney tumors and an ASPSCR-TFE3 PDX model, by immunoblotting and IHC, with increased membrane localization. shRNA-mediated depletion of CD44 profoundly and specifically decreased clonogenicity of multiple TFE3-fusion lines, with no effect seen in ccRCC lines. In conclusion, GPNMB regulates the growth of tRCC cells, potentially via an autocrine mechanism involving its receptor CD44, and targeting GPNMB-CD44 signaling may be of therapeutic benefit in tRCC. Citation Format: Kaushal Asrani, Juhyung Woo, Kewen Feng, Thiago Vidotto, Adrianna Amaral, Vikrant Palande, Jayaprakash Mandal, Eddie Imada, Christopher Thoburn, Sangeeta Ray, Huili Li, Yasser Ged, Nirmish Singla, John A. Copland, Laura Schmidt, W. Marston Linehan, Pedram Argani, Tamara Lotan. GPNMB:CD44 signaling drives tumor progression in translocation renal cell carcinoma [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Innovations in Kidney Cancer Research: From Molecular Insights to Therapeutic Breakthroughs; 2026 Mar 13-16; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2026;86(5_Suppl_2):Abstract nr B014.

Objectives: To report the outcomes of minimally invasive (MIS) nephrectomy following immune checkpoint inhibitor (ICI) therapy. Materials and Methods: This multicenter retrospective cohort study included consecutive patients who underwent nephrectomy following ICI therapy at five high-volume US academic centers between 2015 and 2023. Baseline clinical features and perioperative findings were recorded. After propensity-score matching (PSM), outcomes were compared between MIS and open nephrectomies. The primary outcome was 90-day complications, and secondary outcomes included length of hospital stay (LOS) and 90-day readmission. Results: A total of 158 patients were included, of whom 76 and 82 underwent MIS and open nephrectomies, respectively. The MIS procedures included robotic ( n = 56) and laparoscopic ( n = 20). A total of six (8%) patients converted to open. On multivariable analysis, patients with nonmetastatic vs metastatic renal-cell carcinoma (RCC) (hazard ratio [HR] 3.1, p = 0.01), those with smaller tumor size (HR 1.2 for each cm, p = 0.001), and no clinical evidence of inferior vena cava thrombus (HR 29, p = 0.002) were more likely to undergo the MIS approach compared with open approach. After PSM, including 56 MIS and 36 open nephrectomies, the MIS group compared with the open group had lower estimated blood loss (100 vs 460 mL, p < 0.001) and shorter LOS (2 vs 4 days, p < 0.001). Nevertheless, 90-day complications and readmissions were similar between the two groups. There were no 90-day mortality rates in either group. Conclusion: The MIS approach appears safe and offers more favorable perioperative outcomes compared with open surgery in properly selected patients with advanced RCC who are candidates for nephrectomy following ICI therapy.

Objectives To reassess the role of primary retroperitoneal lymph node dissection (RPLND) in patients with marker‐negative non‐seminomatous germ cell tumour (NSGCT) clinical stage (CS) 2a, to explore results in patients with CS 2b and to evaluate surgical methods, recurrence, and adjuvant chemotherapy indications. Materials and Methods Data from 17 institutions were collected, comprising 305 men who underwent primary RPLND for CS 2 NSGCT. Regression analyses were conducted to predict histology in the RPLND specimen and disease‐free survival (DFS). Results A larger retroperitoneal lymph node diameter was associated with pure teratoma in the RPLND specimen (odds ratio [OR] 1.02, 95% confidence interval [CI] 1.01–1.07; P = 0.03), but no association was observed with DFS. The 5‐year DFS rates in marker negative CS 2a and 2b were 79% and 76%. In men with non‐teratomatous viable cancer in the RPLND specimen, the 5‐year DFS rates for CS 2a and 2b were 95% and 87% with adjuvant chemotherapy, and 67% and 74% without adjuvant chemotherapy. We did not identify an association between the number of adjuvant chemotherapy cycles and DFS. Conclusions Our study suggests considering primary RPLND not only in marker‐negative CS 2a but also in CS 2b. Further research should determine the efficacy of primary RPLND in men with CS 2c and marker‐positive CS 2, as well as which patients may benefit from adjuvant chemotherapy and the optimal cycle number.

516 Background: Based on only smaller retrospective cohort studies, current guidelines recommend primary retroperitoneal lymph node dissection (RPLND) for men with marker-negative stage 2a non-seminomatous germ cell tumor (NSGCT). We aimed to reassess the role of primary RPLND in marker negative stage 2a, explore results in stages 2b/c and/or marker-positive disease, and evaluate surgical methods, recurrence, and adjuvant chemotherapy indications. Methods: Data from 17 institutions were collected, comprising 305 men who underwent primary RPLND for stage 2 NSGCT. Regression analyses were conducted to predict histology in the RPLND specimen and progression-free survival (PFS). Results: A larger retroperitoneal lymph node diameter was associated with pure teratoma in the RPLND specimen (odds ratio [OR] 1.03, 95% confidence interval [CI] 1.01-1.09, p-value = 0.02), but it did not correlate with PFS. The 5-year PFS rates were 85% for men with pure teratoma, 94% for men with viable cancer who received adjuvant chemotherapy, and 72% for men with viable cancer who did not receive adjuvant chemotherapy. The number of adjuvant chemotherapy cycles did not significantly affect PFS. Conclusions: Our study suggests considering primary RPLND not only in marker negative clinical stage 2a but also marker negative clinical stage 2b. Further research should identify the efficacy in men in other stages (2C or marker positive) and which patients may benefit from adjuvant chemotherapy and the optimal cycle number.

475 Background: Emerging evidence supports use of neoadjuvant chemotherapy (NAC) prior to radical nephroureterectomy (RNU) for appropriately selected patients with upper tract urothelial carcinoma (UTUC). However, oncologic outcomes have not been well characterized for patients with residual muscle-invasive disease after NAC. Methods: We used a multi-institutional cohort from 24 centers in the U.S., Europe, and Japan to retrospectively identify patients who underwent RNU for UTUC from 1985-2022 and had high-grade muscle-invasive disease. We stratified the cohort based on receipt of NAC (>ypT2 vs. >pT2). Exclusion criteria included receipt of adjuvant chemotherapy, concurrent cystectomy with RNU, and distant metastatic disease. Baseline characteristics were compared between groups. Kaplan-Meier survival analysis with log-rank test was used to compare differences in recurrence-free survival (RFS), overall survival (OS), and cancer-specific survival (CSS). Multivariable Cox regression and Fine-Gray competing risk regression were used to determine predictors of these outcomes. Results: A total of 1,233 patients were included, 62 of whom received NAC prior to RNU. A platinum-based regimen was used in 90% of NAC recipients, and the median number of cycles administered was 4 (IQR: 3-5). Median follow-up time among all patients was 22 months (IQR: 8-47 mo.). NAC recipients were more likely to have pathologic node positivity (35% vs. 13%) and less likely to have positive tumor margins (8% vs. 28%). On Kaplan-Meier analysis, NAC recipients with residual >ypT2 disease had poorer outcomes than those with >pT2 disease (2-year RFS [NAC vs. no NAC]: 52% vs. 80%, p<0.001; 2-year OS: 60% vs. 78%, p=0.003; 2-year CSS: 61% vs. 86%, p<0.001). Multivariable analyses also showed a statistically significant association between residual muscle-invasive disease after NAC and poorer RFS, OS, and CSS (Table). Conclusions: NAC recipients with >ypT2 disease at RNU after exhibit poorer outcomes than stage-matched chemotherapy naïve counterparts. This may reflect effects of occult micrometastatic disease or chemoresistant primary tumors in non-responders. Our data highlight the need to improve prospective identification of candidates most likely to respond to NAC prior to RNU for UTUC in order to maximize its therapeutic benefit. [Table: see text]