Shah, Pooja A.

Abstract Purpose: Homozygous deletion of the 9p21 locus, containing CDKN2A/B and MTAP [CDKN2A/MTAP deletion (CMdel)], underlies emerging therapeutic strategies, including PRMT5/MAT2A inhibition. The clinicogenomic context and treatment outcome associations of CMdel in non–small cell lung cancer (NSCLC) remain incompletely defined. Experimental Design: We analyzed Tempus Lens records with paired DNA (xT) and RNA (xR) sequencing. After quality filtering (purity ≥40%), 16,947 patients were included in the primary dataset, and 10,996 were included in the validation dataset and stratified by deletion status [CMdel vs. CM wild-type (CMwt)]. IFN status was defined by IFN-kappa (IFNK) expression [log2(TPM + 1)] using the 25th percentile of CMwt as the threshold. Immune composition was inferred by quanTIseq. First-line regimens were grouped as immune checkpoint inhibitor (ICI) monotherapy, ICI chemotherapy, chemotherapy, or tyrosine kinase inhibitors (TKI). Best response and time to next treatment (TTNT) with risk-set adjustment and 18-month truncation were assessed. Results: CMdel occurred in 11.7% (n = 1,991) and 15% (n = 1,676), respectively, and was enriched in mucinous histology, stage IV disease, and never smokers. CMdel was associated with EGFR, TERT, and SMARCA4 alterations, whereas CMwt was associated with RB1, SETD2, and ARID2. More than 50% of CMdel tumors harbored targetable coalterations, enriched in EGFR/ALK/RET and relatively depleted in KRAS. CMdel tumors exhibited lower PD-L1, mutation burden, and immune infiltration. TTNT did not differ by CM status for ICI monotherapy or TKI but was shorter in CMdel for ICI chemotherapy and chemotherapy. Discordant and broad deletions were less common and had weaker TTNT association. IFNK-low expression marked immune-excluded subgroups with worse treatment outcomes. Conclusions: CDKN2A/MTAP loss defines a prevalent, genomically distinct NSCLC subset enriched in actionable drivers. CMdel associates with worse outcomes to ICI/chemotherapy-containing regimens. These findings highlight convergent biology at 9p21 and support biomarker-guided development of PRMT5/MAT2A inhibitors in MTAP-deleted NSCLC.

Abstract Background: Deletions in MTAP occur in 10-15% of cancers and are associated with poor prognosis. MTAP deletion (MTAPdel) leads to accumulation of MTA which causes partial inhibition of PRMT5, creating a synthetic lethality approach with PRMT5 inhibitors. Multiple investigational MTA-cooperative PRMT5 inhibitors have demonstrated early clinical efficacy in MTAPdel NSCLC and other cancers. MTAPdel, PRMT5 expression, and clinical outcomes to standard of care immune checkpoint inhibitors (ICI) and chemotherapy (chemo) have not been well characterized. Methods: The Tempus Lens Platform (Tempus AI, Inc., Chicago, IL) was used to query the Tempus multimodal de-identified database and establish and subsequently analyze a cohort of patients (pts)with NSCLC and DNA (Tempus xT) and RNA (Tempus xR) testing, treated with front-line (1L) ICI with or without chemo (N=3,676). PRMT5 expression was normalized as transcripts per million (TPM) and reported as log2(TPM + 1). Pts were classified into high vs low groups based on median PRMT5 expression and into MTAPdel vs intact (MTAPwt) based on MTAP biallelic loss. Immune infiltration was estimated using Quantiseq. Real-world overall survival (rwOS) was defined as the time from 1L start to death or last known follow-up. Real-world progression-free survival (rwPFS) was defined as the time from 1L start to death, progression or last known follow-up. Hazard ratios (HR) were calculated using Cox proportional hazards models and adjusted for age, sex, histology, smoking status and PDL1 status. Results: PRMT5 expression was moderately increased in pts with MTAPdel (6.65 v 6.70, p=0.012). Alterations in MYC, SMARCA4 and KEAP1 were enriched in PRMT5-high tumors in both MTAPdel and MTAPwt pts (p<0.03). Pts with PRMT5-high tumors had decreased infiltrate of multiple immune cells, including B cells, macrophages (M1 and M2), NK cells, CD4 and CD8 T cells (p<0.001). Pts with MTAPdel/PRMT5-high expression had shorter rwOS compared to MTAPwt/PRMT5-low when treated with ICI alone (HR 1.58, 95% CI 1.11-2.24, p=0.011) or with ICI + chemo (HR 1.65, 95% CI 1.34-2.03, p<0.001). These associations persisted on multivariate analysis. Pts with MTAPdel/PRMT5-high expression were also associated with worse rwPFS when treated with ICI + chemo (HR 1.5, 95% CI 1.22-1.86, p<0.001) on univariate and multivariate analysis, but did not associate with rwPFS in pts treated with ICI alone (HR=0.97, 95% CI 0.66-1.42, p=0.9). Conclusion: PRMT5 expression defines an immune suppressed subpopulation of pts with NSCLC. Pts with elevated PRMT5 expression and MTAPdel have poor outcomes with ICI+/- chemo, indicating PRMT5 RNA expression levels can be used to inform clinical trial designs, particularly those that are testing novel combinatorial strategies. Citation Format: Natalie Vokes, Stamatina Fragkogianni, Pooja A. Shah, Santiago G. Trevino, Konstantinos Leventakos, Lei Deng, Matthew Lee, Tali Azenkot, KAYLA LAYNG, JACOB MERCER, Jyoti Patel, Jordi Rodon Ahnert. High PRMT5 expression is associated with decreased immune infiltrate and worse outcomes to immune checkpoint inhibitors in non-small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 2446.

Abstract Homozygous deletions in the gene encoding methylthioadenosine phosphorylase (MTAP) occur in ∼10% of patients with cancer, including up to 45% in some tumor types, and may be associated with poor prognosis. MTAP deficiency causes accumulation of its catabolic target methylthioadenosine (MTA) that outcompetes S-adenosyl methionine (SAM) for binding to protein arginine methyltransferase 5 (PRMT5), partially inhibiting PRMT5 activity as a posttranslational regulator of a variety of critical cellular functions. Prior anticancer treatments developed to target PRMT5 exhibited high rates of dose-limiting hematologic toxicities because of a lack of selectivity for tumor cells. More recently, several agents have been developed that exploit the vulnerability of MTAP-deleted cancer cells to further inhibition of the PRMT5 pathway, selectively inducing synthetic lethality in those cancer cells. MTA-cooperative PRMT5 inhibitors such as BMS-986504/MRTX1719 and AMG 193 target the PRMT5–MTA complex, whereas inhibitors of the SAM synthetase methionine adenosyl transferase 2A, such as IDE397, deprive PRMT5 of its methyl donor SAM. In this review article, we summarize the mechanisms of action, preclinical data, and clinical data available thus far for these novel classes of oncology precision medicine and discuss potential future directions relevant to MTAP deletion as a promising synthetic lethal vulnerability for cancer therapy.

Abstract Deletions in 9p21 are common across multiple cancer types including NSCLC. Notably, 9p21 deletions have been implicated in an immune-excluded tumor immune phenotype and worse outcomes following ICIs. Whether this effect is due to CDKN2A loss, collateral loss of MTAP, or loss of type I interferon genes (IFNK, IFNA) has not been fully adjudicated. The Tempus Database (Tempus AI, Inc., Chicago, IL) was queried for de-identified records of patients with NSCLC and DNA (Tempus xT) and RNA (Tempus xR) molecular profiling. CDKN2A/MTAP deleted samples were defined as those containing biallelic loss of CDKN2A/B and MTAP. As IFNK is not included in the DNA sequencing bait set, IFNK status was defined as low in any sample with expression ≤ the first quartile of IFNK expression from samples with intact CDKN2A/B and MTAP. Samples with tumor purity < 40% or mixed loss of CDKN2A/B and MTAP were excluded. Association analysis of CDKN2A/MTAP/IFNK status with other genomic events and clinical outcomes was performed. N=16, 947 patients were included in the overall analysis, of whom n=1, 991 had CDKN2A/B/MTAP deletion (11.7%, CMdel). Significantly more CMdelpatients had low IFNK expression compared to CDKN2A/B/MTAP intact (CMwt) patients (n=14, 956); of CMdel(n=1300), 65.3% had high IFNK expression (IFNKhi) and 34.7% had low IFNK expression (IFNKlo). Among CMdelpatients, IFNKhisamples were enriched in never smokers compared to IFNKlopatients (24% vs 18%, p=0.002). CMdel was enriched in samples with EGFR and ALK driver alterations, and depleted in samples with KRAS or TP53 alterations. In both CMdeland CMwtcontexts, KRAS, EGFR, and ALK alterations associated with IFNKhiexpression, whereas TP53, NFE2L2, STK11, KEAP1, SMARCA4, and KMT2D associated with IFNKloexpression. IFNKhiexpression within CMdelpatients was associated with an increase in the estimated proportion of immune cell subpopulations, including CD8 T cells and macrophages (M1 and M2), and a decrease in neutrophils and NK cells. In metastatic/unresectable stage III patients with recorded ICI-containing 1L therapies (n=1, 795), patients with CMdeland IFNKlotrended toward higher rates of progressive disease (PD) (37%), whereas CMdel/IFNKhihad comparable rates of PD to CMwtl/IFNKhiand CMwtl/IFNKlo(28%, 27%, 30%, respectively). CMdel/IFNKlopatients treated with non-ICI/TKI therapies (mostly consisting of chemotherapy) had a non-significant trend toward increased rate of PD (63%). CMdelassociates with driver alterations in EGFR and ALK, along with worse ICI and chemotherapy outcomes in the context of IFNKlobut not IFNKhi expression. Further work to disentangle the impact of immune infiltrate and the co-mutation landscape will help clarify the underlying associated biology. Citation Format: Natalie Vokes, Jessica L. Symons, Brooke Rhead, Pooja A. Shah, Santiago Trevino, Konstantinos Levantakos, Stamatina Fragkogianni, Calvin Chao, Jordi A. Rodon. Low interferon expression coupled with 9p21 loss in non-small cell lung cancer (NSCLC) patients associated with distinct somatic landscape, altered immune population, and poorer response to immune checkpoint inhibitor (ICI) therapies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 6620.