a wholly owned subsidiary of Takeda Pharmaceutical Company Limited. Dr. Sheldon-Waniga reports current employment by Bluebird Bio and previous employment by Millennium Pharmaceuticals, Inc., Cambridge, MA, USA, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited. Dr. Ecsedy reports current employment by Kyn Therapeutics and previous employment by Millennium Pharmaceuticals, Inc., Cambridge, MA, USA, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited. Dr. Ullmann reports current employment by MaxCyte, Inc., and previous employment by Millennium Pharmaceuticals, Inc., Cambridge, MA, USA, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited. Dr. Byers reports clinical trial research funding and a preclinical (laboratory) research grant to her institution from Takeda, as well as personal fees from
BackgroundImmune checkpoint inhibitors (ICIs) have expanded treatment options for metastatic renal cell carcinoma (mRCC); however, there are limited predictive biomarkers for response to ICIs in this indication, with programmed death-ligand 1 (PD-L1) status demonstrating little predictive utility in mRCC. While predictive of ICI response in other tumor types, the utility of tumor mutation burden (TMB) in mRCC is unclear. Here, we assess TMB, loss of antigen presentation genes and PD-L1 status correlated with outcomes to ICI treatment in mRCC.MethodsTumor samples from 34 patients with mRCC treated with ICI therapy at Duke Cancer Institute were retrospectively evaluated using Personal Genome Diagnostics elio tissue complete (RUO version), a tumor genomic profiling assay for somatic variants, TMB, microsatellite status and genomic status of antigen presentation genes. Tumor samples were also analyzed with the Dako 28-8 PD-L1 immunohistochemistry assay. Deidentified clinical information was extracted from the medical record, and tumor response was evaluated based on the Response Evaluation Criteria In Solid Tumors (RECIST) V.1.1 criteria.ResultsPatients were stratified by overall response following ICI therapy and designated as progressive disease (PD; n=18) or disease control groups (DC; n=16). TMB scores ranged from 0.36 to 12.24 mutations/Mb (mean 2.83 mutations/Mb) with no significant difference between the PD and DC groups (3.01 vs 2.63 mutations/Mb, respectively; p=0.7682). Interestingly, 33% of PD patients displayed loss of heterozygosity of major histocompatibility complex class I genes (LOH-MHC) vs 6% of DC patients. Nine of 34 samples were PD-L1-positive (4 in the PD group; 5 in the DC group), suggesting no correlation between PD-L1 expression and response to ICI therapy. Notably, the DC group displayed an enrichment of mutations in DNA repair genes (p=0.04), with 68.8% exhibiting at least one mutated homologous recombination repair (HRR)-related gene compared with only 38.9% of the PD group (p=0.03).ConclusionsOverall, neither TMB nor PD-L1 correlated with ICI response and TMB was not significantly associated with PD-L1 expression. The higher incidence of LOH-MHC in PD group suggests that loss of antigen presentation may restrict response to ICIs. Separately, enrichment of HRR gene mutations in the DC group suggests potential utility in predicting ICI response and a potential therapeutic target, warranting future studies.
589 Background: ICIs have revolutionized treatment for mRCC; however there are limited predictive biomarkers for response to ICIs. PD-L1 status is still controversial demonstrating little predictive utility in mRCC. TMB is predictive for response to ICIs in melanoma and non-small cell lung cancer (NSCLC), but has not been validated in mRCC. Here, we assess the correlations between TMB and PD-L1 status with outcomes to ICI treatment in mRCC. Methods: 34 patients (pts) with mRCC who had previously received ICI therapy at Duke Cancer Institute were identified. Tumor samples were retrospectively evaluated using a Personal Genome Diagnostics Assay for somatic variants across > 500 genes, as well as TMB and microsatellite status. Tumor samples were also analyzed with the Dako 28-8 PD-L1 IHC assay. Deidentified clinical information was extracted from the medical record and tumor response was evaluated based on RECIST criteria. Results: Pts were grouped by overall response following ICI therapy into either progressive disease (“PD”, n = 18) or disease control group (“DC”, n = 16), defined as either stable disease, partial response, or complete response. Pts displayed a TMB range from 0.36 to 12.24 mutations/Mb with a mean score of 2.83 muts/Mb, with no significant difference between the PD and DC groups (mean 3.01 muts/Mb vs. 2.63 muts/Mb, p > 0.05). 9 of 32 evaluable samples were PD-L1 positive, with 4 in the PD group and 5 in the DC group. Notably, the DC group displayed a significant enrichment of mutations in genes affiliated with DNA repair (including BRCA1, BRCA2, FANCA, FANCB, FANCG, FANCM, MSH3, MSH6, RAD50, RAD51C, RAD51D, RAD54B, RECQL4, and SLX4; p = 0.0444). Conclusions: Overall, in this mRCC cohort, neither TMB nor PD-L1 correlated with patient outcomes or with ICI response. Furthermore, high TMB was not significantly associated with PD-L1 expression within the samples. The higher frequency of mutations in DNA repair genes in the DC group suggests potential use as a predictive signature for ICI response, warranting future prospective studies.
e16079 Background: ICIs have revolutionized treatment for mRCC; however there are limited predictive biomarkers for response to ICIs. PD-L1 status is still controversial, demonstrating little predictive utility in mRCC. TMB is predictive for response to ICIs in melanoma and non-small cell lung cancer (NSCLC), but has not been validated in mRCC. Here, we assess the correlations between TMB and PD-L1 status with outcomes to ICI treatment in mRCC. Methods: 34 patients (pts) with mRCC who had previously received ICIs at Duke Cancer Institute were identified. Tumor samples were retrospectively evaluated using a Personal Genome Diagnostics Assay for somatic variants across > 500 genes, as well as TMB and microsatellite status. PD-L1 status was tested via the Dako 28-8 PD-L1 IHC assay. Deidentified clinical information was extracted from the medical record and tumor response was evaluated based on RECIST criteria. Results: Pts were grouped by overall response following ICI therapy into either progressive disease (“PD”, n = 18) or disease control group (“DC”, n = 16), defined as either stable disease, partial response, or complete response. Pts displayed a TMB range from 0.36 to 12.24 mutations/Mb with a mean score of 2.83 muts/Mb, with no significant difference between the PD and DC groups (mean 3.01 muts/Mb vs. 2.63 muts/Mb, p > 0.05). 9 of 32 evaluable samples were PD-L1 positive, with 4 in the PD group and 5 in the DC group. Notably, the DC group displayed a significant enrichment of mutations in genes affiliated with DNA repair (including BRCA1, BRCA2, FANCA, FANCB, FANCG, FANCM, MSH3, MSH6, RAD50, RAD51C, RAD51D, RAD54B, RECQL4, and SLX4; p = 0.0444). DNA damage gene mutations were found in 8/10 (80%) metastatic tumor specimens and 14/24 (58%) primary tumors. Conclusions: Overall, in this mRCC cohort, neither TMB nor PD-L1 correlated with patient outcomes or with ICI response. Furthermore, high TMB was not significantly associated with PD-L1 expression within the samples. The higher frequency of mutations in DNA repair genes in the DC group suggests potential use as a predictive signature for ICI response, warranting future prospective studies. Further studies with matched primary-metastatic samples would be beneficial to determine if DNA repair mutations occur more frequently in metastatic versus primary tumor specimens.
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