Leventakos, Konstantinos

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.

Adoptive cellular immunotherapy (ACT) has revolutionized hematologic malignancies, yet translation to solid tumors has historically been limited. This landscape shifted significantly in 2024 with US Food and Drug Administration approvals of lifileucel, a tumor-infiltrating lymphocyte (TIL) therapy for advanced melanoma, and afamitresgene autoleucel, an engineered T-cell receptor (TCR) therapy for synovial sarcoma. These approvals mark the clinical arrival of ACT for solid tumors and highlight a rapidly expanding therapeutic landscape. Beyond these indications, multiple ACT platforms including TIL, TCR, chimeric antigen receptor (CAR) T-cell, CAR-natural killer, and CAR-macrophage therapies are under active clinical investigation across diverse solid tumor indications. Clinical experience to date has defined key barriers to efficacy, including impaired tumor trafficking, antigen heterogeneity, immunosuppressive tumor microenvironment, and limited cellular persistence. In parallel, rapid advances in cellular engineering are reshaping the field, with the development of armored constructs, logic-gated and multiantigen targeting strategies, innate immune–based platforms, and novel manufacturing approaches including allogeneic and in vivo cell engineering. As ACT enters clinical practice for select solid tumors, distinct toxicity profiles and logistical requirements necessitate careful patient selection and multidisciplinary coordination. Early biomarker testing, timely referral to specialized centers, and familiarity with evolving toxicity management frameworks are increasingly critical. Here, we seek to provide a practice-oriented framework for understanding emerging ACT platforms, clinical data, toxicity considerations, and implementation strategies relevant to contemporary solid tumor oncology care.

Abstract Previous studies implicated protein arginine methyltransferase 5 (PRMT5) as a synthetic lethal target for MTAP-deleted (MTAP del) cancers; however, the pharmacologic characterization of small-molecule inhibitors that recapitulate the synthetic lethal phenotype has not been described. MRTX1719 selectively inhibited PRMT5 in the presence of MTA, which is elevated in MTAP del cancers, and inhibited PRMT5-dependent activity and cell viability with >70-fold selecti­vity in HCT116 MTAP del compared with HCT116 MTAP wild-type (WT) cells. MRTX1719 demonstrated dose-dependent antitumor activity and inhibition of PRMT5-dependent SDMA modification in MTAP del tumors. In contrast, MRTX1719 demonstrated minimal effects on SDMA and viability in MTAP WT tumor xenografts or hematopoietic cells. MRTX1719 demonstrated marked antitumor activity across a panel of xenograft models at well-tolerated doses. Early signs of clinical activity were observed including objective responses in patients with MTAP del melanoma, gallbladder adenocarcinoma, mesothelioma, non–small cell lung cancer, and malignant peripheral nerve sheath tumors from the phase I/II study. Significance: PRMT5 was identified as a synthetic lethal target for MTAP del cancers; however, previous PRMT5 inhibitors do not selectively target this genotype. The differentiated binding mode of MRTX1719 leverages the elevated MTA in MTAP del cancers and represents a promising therapy for the ∼10% of patients with cancer with this biomarker. See related commentary by Mulvaney, p. 2310. This article is featured in Selected Articles from This Issue, p. 2293