Multi-omic analysis of the prognostic and predictive value of LAG3 expression in urothelial carcinoma.

person Adanma Ayanambakkam Stephenson Cancer Center, University of Oklahoma Health Sciences Center, Oklahoma City, OK info_outline Adanma Ayanambakkam, Anh B. Lam, Kieran Sweeney, Chao Xu, Andrew Elliott, Seven Tomek, Chadi Nabhan, Sumati Gupta, Jad Chahoud, Debasish Sundi, William Paul Skelton, Laura Graham, Lyudmyla Derby Berim, Bodour Salhia, Sean Kern, Stephen B. Edge, Yousef Zakharia, Abhishek Tripathi, Rana R. McKay, Abdul Rafeh Naqash

Authors person Adanma Ayanambakkam Stephenson Cancer Center, University of Oklahoma Health Sciences Center, Oklahoma City, OK info_outline Adanma Ayanambakkam, Anh B. Lam, Kieran Sweeney, Chao Xu, Andrew Elliott, Seven Tomek, Chadi Nabhan, Sumati Gupta, Jad Chahoud, Debasish Sundi, William Paul Skelton, Laura Graham, Lyudmyla Derby Berim, Bodour Salhia, Sean Kern, Stephen B. Edge, Yousef Zakharia, Abhishek Tripathi, Rana R. McKay, Abdul Rafeh Naqash Organizations Stephenson Cancer Center, University of Oklahoma Health Sciences Center, Oklahoma City, OK, University of Oklahoma Health Sciences Center, Oklahoma City, OK, Caris Life Sciences, Irving, TX, Caris Life Sciences, Phoenix, AZ, Caris Life Sciences and the University of South Carolina, Deerfield, IL, Huntsman Cancer Institute at the University of Utah, Salt Lake City, UT, Department of Genitourinary Medical Oncology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, The Ohio State University, Columbus, OH, University of Virginia Comprehensive Cancer Center, Charlottesville, VA, University of Colorado Cancer Center Anschutz Medical Campus, Aurora, CO, Rutgers Cancer Institute of New Jersey, New Brunswick, NJ, Department of Translational Genomics, Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, Indiana University, Indianapolis, IN, Department of Surgical Oncology, Roswell Park Cancer Institute, Buffalo, NY, University of Iowa Holden Comprehensive Cancer Center, Iowa City, IA, Department of Medical Oncology & Experimental Therapeutics, City of Hope Comprehensive Cancer Center, Duarte, CA, University of California, San Diego Health, La Jolla, CA, University of Oklahoma Health Sciences Center, Stephenson Cancer Center, Oklahoma City, OK Abstract Disclosures Research Funding No funding sources reported Background: Lymphocyte-activation gene 3( LAG3 ) is an immune checkpoint protein expressed on immune cells that inhibits T-cell function. Despite its established prognostic significance in other malignancies, the role of LAG3 as a prognostic or predictive biomarker in urothelial carcinoma (UC) remains inadequately studied. Methods: DNA (592-gene or whole exome) and RNA (whole transcriptome) sequencing were performed for patient tumors submitted to Caris Life Sciences. PD-L1+ status (22c3, combined positive score≥10) was determined by IHC. TMB-High (TMB-H) was defined as ≥10 mutations/Mb. LAG3 high ( LAG3 -H) and low ( LAG3 -L) groups were defined by the top and bottom quartiles of LAG3 RNA transcripts per million, respectively. Tumor microenvironment (TME) cell fractions were estimated by RNA deconvolution using quanTIseq. Significance was tested using Mann-Whitney U and 𝜒 2 tests as appropriate. Real-world median overall survival (mOS) was obtained from insurance claims data and calculated from treatment start to last contact, while time-on-treatment (ToT) was calculated from treatment start to end. Hazard ratio (HR) was calculated using the Cox proportional hazards model, and p-values were calculated using the log-rank test. Clinical and RNA-seq data from patients enrolled in the Oncology Research Information Exchange Network (ORIEN) were used to validate the analysis. Results: Among 3343 UC cases, LAG3 -H was associated with increased TP53 (70.6% vs 49.4%, q<10 -4 ) and RB1 mutations (31.0% vs 18.0%, q<10 -4 ), decreased FGFR3 mutations (6.0% vs 18.1%, q<10 -4 ), and increased TMB-H (50.1% vs 36.7%, q<10 -4 ) and PD-L1+ status (71.0% vs 16.2% 22c3, q<10 -4 ). LAG3 -H tumors had increased infiltration of CD8+ (1.5% vs 0.0%, q<10 -4 ) and NK (2.3% vs 1.6%, q<10 -4 ) cells, but also higher levels of inhibitory Tregs (3.3% vs 1.4%, q<10 -4 ). No significant difference was found in mOS of patients with LAG3-H, when comparing low vs high levels of FGL1 expression (HR=0.934, p=0.51). Among patients who received an immune checkpoint inhibitor (ICI; N=675), multivariate analysis using Cox proportional hazard regression revealed that LAG3 -H had improved mOS vs LAG3 -L (HR=0.720, p=0.002) after accounting for potential confounders (sex, TMB, TP53 , and FGFR3 ). LAG3 -H also had significantly improved mOS vs LAG3 -L in PD-L1+ patients given ICI (N=291, HR=0.605, p=0.009). LAG3 expression was also higher in patients with above median ToT on avelumab (1.4-fold, p=0.049) and pembrolizumab (1.2-fold, p=0.022). Improved mOS for LAG3 -H vs LAG3-L patients (HR=0.65, p=0.036) were validated using the ORIEN database. Conclusions: Increased LAG3 expression in UC correlates with a distinct mutational landscape, an inflamed TME characterized by augmented immune cell infiltration, prolonged ICI ToT, and significant improvements in mOS. These findings corroborate the potential for dual LAG3 PD1 blockade in UC.