Spira, Alexander I.

TPS3678 Background: Advanced and metastatic colorectal cancer (CRC) remains an area of significant unmet clinical need, particularly for patients with MSS/MSI-L tumors. In recent years, there have been several advancements in the treatment of solid tumors with T cell engagers. Our ATLAS scRNA-seq based discovery platform identified LY6G6D as a highly-specific tumor-associated antigen in advanced and metastatic CRC. CBI-1214, a CD3 bispecific T cell engager targeting LY6G6D with potent in vitro and in vivo activity even at low LY6G6D expression levels of ~300 copies/cell ( Yigit B et al, AACR 2025 ), is being developed for the treatment of patients with advanced or metastatic MSS/MSI-L CRC. Methods: This ongoing, open-label FIH study (CBI-1214-001) is being conducted to evaluate the safety, tolerability, pharmacokinetics (PK), and anti-tumor activity of CBI-1214 and to determine the maximum tolerated dose (MTD) and/or optimal biological dose (OBD) in participants with advanced or metastatic MSS/MSI-L CRC who have exhausted at least one prior line of systemic treatment and do not qualify for available targeted treatment options for actionable genomic alterations. Additional eligibility criteria include: at least 18 years of age, measurable disease (as defined by RECIST v1.1), available archival tumor tissue sample or a fresh tumor sample, ECOG PS 0 or 1, as well as adequate hematologic and organ functions. Patients whose CRC tumor tissues have been identified as dMMR or MSI-H are excluded. The study is conducted in two parts: Part 1 dose escalation, which starts with Part 1a as accelerated dose escalation, followed by Part 1b escalation, which is based on a modified toxicity probability interval (mTPI-2) design, and Part 2, which is designed as a randomized dose optimization study to select the final recommended phase 2 dose (RP2D). For both parts of the study, the study intervention is administered as monotherapy, given as an intravenous (IV) infusion, in 21-day treatment cycles, with a step-up option. After an up-to-28-day screening period, eligible patients receive study medication and are followed for their entire treatment period plus a follow-up period of approximately 90 days. The study is open for recruitment in the United States (NCT07321106). Clinical trial information: NCT07321106 .

3146 Background: The MTA-cooperative PRMT5 inhibitor BMS-986504 selectively binds to the PRMT5-MTA complex, a synthetic lethal target in MTAP -del cancer cells, while sparing MTAP –wild-type normal cells. In the phase 1 CA240-0007 study, BMS-986504 was well tolerated and had antitumor activity in pts with MTAP -del advanced solid tumors (ORR, 23%; median DOR, 10.5 mo). BMS-986504 also demonstrated dose-dependent reductions in plasma symmetric dimethylarginine (SDMA) levels, a PD biomarker of PRMT5 inhibition. Here, we report expanded PD and genomic analyses and initial results of exploratory proteomic analyses from CA240-0007. Methods: Pts with advanced, unresectable, or metastatic solid tumors with homozygous MTAP -del received BMS-986504 (50–800 mg) in 3-wk cycles. Analyses of SDMA levels and proteomic profiles from paired plasma samples (baseline and C2D1) were performed using mass spectrometry and SomaScan 11K, respectively. Tumor genomic information was extracted from local pathology reports. ORR was assessed per RECIST v1.1. Results: Among 78 pts with paired samples at data cutoff (22 Sept 2025; median f/u, 15.9 mo), dose-dependent reductions were seen in plasma SDMA levels, with the greatest reductions at 400 mg QD (median, 60.3%; n = 31) and 600 mg QD (median, 60.3%; n = 23). Proteomic pathway enrichment analysis demonstrated downregulation of PI3K/Akt/mTOR, Myc target, cell cycle, and DNA damage repair (DDR) pathways with BMS-986504 on C2D1 (n = 87), consistent with the expected effect of PRMT5 inhibition; a trend toward deeper modulation of PRMT5-regulated pathways was observed at higher doses. No proteins at baseline (n = 94) were found to be significantly associated with ORR (false discovery rate > 0.05). Responses in clinically evaluable pts with NSCLC (n = 33) or PDAC (n = 35) were observed regardless of EGFR , KRAS , or TP53 status. In pts with NSCLC, STK11 and SMARCA4 alterations were numerically higher in nonresponders. No gene alterations were associated with response in PDAC, except GABRA6 alterations (n = 2, both responders). A trend toward higher ORRs was seen in pts with alterations in DDR genes ( CHEK2, FANCD2, XRCC4 , and/or MSH2 ), consistent with the role of PRMT5 in DDR via regulation of mRNA splicing. ctDNA analysis will be presented. Conclusions: BMS-986504 demonstrated robust dose-dependent PD effects in pts with advanced solid tumors in plasma SDMA and proteomic analyses. Downregulation of PRMT5-regulated pathways was observed with BMS-986504 treatment. Response was seen regardless of EGFR, KRAS , and TP53 alterations in NSCLC or PDAC, and DDR gene alterations were associated with improved response. These findings further support the MOA of BMS-986504 and its ongoing investigation in the phase 2/3 MountainTAP-9, -29, and -30 studies as a potential treatment option in pts with MTAP -del advanced solid tumors. Clinical trial information: NCT05245500 .

3109 Background: Poly(ADP-ribose) glycohydrolase (PARG) is an enzyme that catalyzes the removal of poly-ADP-ribose (PAR) chains from proteins during DNA damage repair. PARG inhibition leads to selective cell death in tumors with underlying replication fork defects, including BRCAm tumors, through a mechanism distinct from PARP inhibition. ETX-19477 is an oral, potent, and selective PARG inhibitor that shows robust preclinical activity in mouse models of ovarian, breast, and gastric cancers. Methods: ERADIC8 is an open-label, multicenter, Phase 1/2 study, consisting of two parts, dose escalation and dose expansion. A Bayesian Optimal Interval Design was used to enroll patients (pts) into dose escalation cohorts, with enrichment for pts with BRCAm high grade serous ovarian (HGSOC) and breast cancers. The primary objective is to assess safety/tolerability of ETX-19477 and define the maximum tolerated dose (MTD) and recommended Phase 2 dose(s). Secondary and exploratory objectives include pharmacokinetics, pharmacodynamics, and preliminary anti-tumor activity per RECIST v1.1. ETX-19477 is given orally once or twice daily in 21-day cycles. Results: As of Jan 6 2026, 45 pts were enrolled into the study across 11 dose levels (range: 80-750 mg QD, 190-350 mg BID). Tumor types included ovarian (n=24, BRCAm: 18), breast (n=8, BRCAm: 7), endometrial (n=6, BRCAm: 0), colorectal (CRC, n=3, BRCAm: 1), and other (n=4, BRCAm: 0) cancers. Treatment-related AEs (TRAEs; any grade) occurring in >20% of pts were nausea (53%), vomiting (38%), and fatigue (24%). The only Gr3 TRAE occurring in >5% of pts was neutropenia (16%). There was one Gr4 TRAE of neutropenia in 1 pt (2%) and no Gr5 TRAEs. ETX-19477 exposure is dose proportional, and the BID regimen achieves >85% PARG inhibition throughout the dosing interval in a blood-based PAR accumulation pharmacodynamic assay. As of the data cutoff, dose escalation is ongoing at 350 mg BID (MTD has not been defined) and dose expansion is ongoing at 200-300 mg BID. Among BRCAm, HGSOC pts enrolled at BID dose levels, there were 7 evaluable pts with a median of 4 prior lines of therapy (range 2–11): 2 pts achieved a partial response (PR, 29%) and 3 pts achieved stable disease (SD, 43%). Both pts with PRs were platinum-resistant and received prior PARP inhibitor treatment. 1 pt with BRCAm CRC remains on active therapy (250 mg BID) with SD for 7 months. Conclusions: ETX-19477 was well tolerated and showed anti-tumor activity in heavily pretreated pts with BRCAm, platinum-resistant HGSOC during dose escalation. These findings provide the first clinical proof-of-concept of PARG inhibition in HGSOC. ETX-19477 is being further evaluated in the dose expansion phase of the study. Clinical trial information: NCT06395519 .

3014 Background: Macrocyclic next-generation tyrosine kinase inhibitors (TKIs) have transformed outcomes in ALK- and ROS1-positive NSCLC; such creatively designed medicines are similarly needed to improve outcomes in EGFR-mutant NSCLC. Using a novel, mutant-selective macrocyclic structure, BH-30643 was designed for super-potency against driver EGFRm, largely sparing wildtype (WT) EGFR, and with unique invulnerability to resistance from C797S with or without T790M. Here we report emerging first-in-human dose-escalation data from the SOLARA trial (NCT06706076). Methods: Phase 1 dose escalation used a BOIN design with backfill at potentially efficacious doses. Expansion cohorts targeted populations of interest. Patients (pts) had advanced NSCLC with EGFR and/or HER2 mutations detected on local testing (tissue or plasma). Measurable disease was required; asymptomatic untreated brain metastases (BM) were permitted. Objectives included safety, PK, and RECIST response rate (ORR). Plasma NGS was performed at baseline and on treatment. Results: As of 01/05/2026, 72 pts enrolled into dose escalation and backfill across 7 dose levels at a total daily dose of 20mg -160mg, median age 62, 44% Asian, 65% with history of BM, median of 3 prior lines of treatment (range 1-12). EGFR mutations included classical (38 pts), exon20ins (14 pts) and other/atypical (18 pts) or HER2 mutations (2 pts). Plasma exposures at doses of 40mg BID and above achieved > 10x coverage over target EC90 and exceeded exposure levels of most contemporary EGFR TKIs. Common TRAE ( > 10%) were WT EGFR-associated, including diarrhea (38%), rash (28%), fatigue (15%), stomatitis (13%), and were predominantly grade 1. Bilirubin elevation was seen in 26 pts (36%) related to off-target UGT1A1 inhibition (Gilbert’s-like). Grade 3 TRAE were seen in 15 pts (18%), most commonly bilirubin (8/15); DLTs included bilirubin increase and mucositis, occurring at doses ≥ 60mg BID. No pneumonitis was observed. Responses were observed across diverse EGFRm subsets, including in CNS. Including expansion pts, 28 pts enrolled with C797S on their most recent informative molecular testing (6 with concurrent MET+ or KRAS+), with 23 still on therapy. Of 17 with on-treatment scans, partial responses (confirmed or ongoing) were seen in 10 (59%); ORR was comparable with (50%) or without (66%) T790M. Of 9 pts with baseline C797S detected in ctDNA (3 with T790M), 7 had > 99% reduction of C797S VAF on treatment. Conclusions: Leveraging a novel macrocyclic scaffold, BH-30643 is the first TKI monotherapy to demonstrate clinical responses against C797S both with or without T790M. High plasma exposures combined with super-potency, CNS activity, and favorable safety offers potential for deep and durable EGFR inhibition. Enrollment into backfill and expansion cohorts is ongoing to better characterize activity in both TKI-naïve and resistant pts. Clinical trial information: NCT06706076 .

3553 Background: Vilastobart (XTX101) is tumor-activated, high affinity, Fc-enhanced aCTLA-4 designed to focus activity toward the tumor and minimize systemic adverse events. Fc-enhancement augments FcγR co-engagement on antigen presenting cells and has been linked with efficacy of aCTLA-4 combinations in patients (pts) with microsatellite stable (MSS) colorectal cancer (CRC) and other tumors [Fakih ASCO GI 2025]. Vilastobart was generally well-tolerated and demonstrated evidence of anti-tumor activity in pts with immunologically “cold” advanced solid tumors, both as a monotherapy and in combination with atezolizumab [Davar SITC 2024]. Methods: Phase 2 of the NCT04896697 study evaluated the initial recommended Phase 2 dose of vilastobart 100 mg Q6W in combination with atezolizumab 1200 mg Q3W in pts with MSS CRC who had at least 1 prior chemotherapy regimen in the metastatic setting, excluding pts with prior immune checkpoint inhibitors. Pts with (LM) and without liver metastasis (NLM) were eligible. Tumor biopsies were obtained before and during treatment for translational analyses. Results: As of January 13, 2025, 40 pts were dosed in Phase 2. Median age was 55 (25-82) and 70% of pts had 3 or more prior lines of therapy. Of the 24 enrolled NLM pts, 11 were response-evaluable with an available on-treatment scan as of the data cut. In these 11 pts, two confirmed and one unconfirmed partial response (PR) were reported, all accompanied by significant decreases in ctDNA and serum tumor marker CEA and with each pt ongoing on therapy, for a preliminary ORR of 27%. One additional pt (with peritoneal metastasis) had a 24% reduction in target lesions (first scan) and was ongoing on therapy. Of the 16 enrolled LM pts, 7 were response evaluable, with one stable disease and another pt reporting a mixed response with significant serum tumor marker reductions, both ongoing on therapy. Of note, one LM pt in Phase 1C dose escalation treated with vilastobart (150 mg Q6W) combination had a confirmed PR with LM resolution. Six pts (15%) reported G3+ treatment-related adverse events (TRAEs), with two G4 laboratory TRAEs and no G5 TRAEs. Only three pts discontinued therapy for TRAEs. TRAEs occurring in ≥10% (all grade) or ≥5% (G3) of pts are summarized in the Table. Conclusions: The combination of vilastobart, a novel tumor-activated, Fc-enhanced a-CTLA-4, and atezolizumab demonstrated initial evidence of anti-tumor activity in late line, metastatic MSS CRC where immune checkpoint blockade has historically been relatively ineffective. Vilastobart was observed to have a differentiated safety profile distinct from systemically active a-CTLA-4, consistent with tumor-selective activation. Clinical trial information: NCT04896697 . AE term All Graden (%) Grade 3n (%) Fatigue 12 (30%) 0 Diarrhea 8 (20%) 0 Infusion related reactions 5 (13%) 0 Pyrexia 4 (10%) 0 ALT increased 4 (10%) 0 AST increased 4 (10%) 1 (3%) Colitis 2 (5%) 2 (5%)

3011 Background: BMS-986504 selectively binds to the PRMT5-MTA complex, which represents a synthetic lethal target in MTAP -del cancer cells, while sparing MTAP– wild-type cells. In the first-in-human phase 1/2 CA240-0007 study in advanced, unresectable or metastatic solid tumors with homozygous MTAP -del, BMS-986504 was found to be well tolerated and demonstrated antitumor activity in multiple tumors. Here, we report clinical results and the first PK and PD analyses of BMS-986504 from the dose escalation and expansion phases of CA240-0007. Methods: Pts with measurable/evaluable disease and no available treatment (Tx) with curative intent were enrolled; 7 doses were evaluated (50 to 800 mg) in dose escalation. Objective response rate (ORR), disease control rate (DCR), duration of response (DOR), time to response (TTR), safety, PK, PD, including plasma SDMA were assessed. Results: As of 2 Dec 24, 152 heavily pretreated pts were enrolled across all doses: NSCLC (n = 34), PDAC (n = 41), cholangiocarcinoma (n = 12), and mesothelioma (n = 12) were the most common tumor types. With a median f/u of 9.0 mo (95% CI 7.6–9.9), continued durable antitumor activity and deepening tumor regression were seen across tumor types and doses (ORR = 23%, DCR = 70%, median DOR = 10.5 mo, TTR = 4.6 mo). No new safety signals were identified. Most Tx-related adverse events (TRAEs) were grade (Gr) 1 or 2; 13% had Gr ≥ 3 TRAEs (Gr 3 = 12%, Gr 4 = < 1%, Gr 5 = 0). Doses from 50 to 600 mg QD were assessed for PK/PD. The AUC (0-24) after multiple doses was approximately dose proportional at 200 to 600 mg, and the terminal t 1/2 after a single dose was approximately 24 h (table). There were dose-dependent reductions in predicted plasma SDMA, with the 400 and 600 mg doses approaching the plateau. Conclusions: With longer f/u, BMS-986504 continued to show increasingly durable antitumor activity. BMS-986504 demonstrated a favorable PK/PD profile, supporting QD dosing at 400 and 600 mg. These results support further investigation of BMS-986504 at 400 and 600 mg QD as a potential first-in-class synthetic lethal Tx option in pts with advanced solid tumors with MTAP -del. Clinical trial information: NCT05245500 . PK and PD. 50 mg QD 100 mg QD 200 mg QD 400 mg QD 600 mg QD PK after multiple doses t max a (min–max), h 2.0 (2.0–4.0)n = 3 2.0 (1.0–2.0)n = 3 2.0 (0.5–6.0)n = 8 2.0 (0.5–4.0)n = 10 2.0 (1.0–6.0)n = 10 C max , b ng/mL 107n = 3 377n = 3 685n = 8 1240n = 10 2110n = 10 AUC (0-24) , b h∙ng/mL 948 n = 3 3060 n = 3 7150 n = 7 11,800n = 10 26,700n = 9 AUC (0-24) , b,c h∙ng/mL/mg 19.0n = 3 30.6n = 3 35.8n = 7 29.5n = 10 44.6n = 9 Terminal t 1/2 after single dose, d h 21.7 n = 1 80.7 n = 1 21.5 n = 14 21.7 n = 14 24.1 n = 1 PD Translational exposure targets (C avgss ), X 0.08 0.21 0.5 1.1 1.7 Predicted plasma SDMA reduction, a % (90% PI) 30.0 (23.2–37.8) 38.8 (27.1–47.5) 48.3 (42.0–53.0) 55.0 (50.7–57.6) 57.4 (54.3–59.0) a Median. b Geometric mean. c Dose-normalized. d Arithmetic mean.

Abstract Background: Effective treatments (Tx) are needed for MTAP-del cancers (10-15% of all cancers). BMS-986504 (formerly MRTX1719) is a potential first-in-class MTA-cooperative protein arginine methyltransferase 5 (PRMT5) inhibitor that selectively binds to the PRMT5-MTA complex, a synthetic lethal target in MTAP-del but not MTAP-wild-type cells. In the first-in-human phase 1/2 CA240-0007 study, BMS-986504 was well tolerated and showed clinical activity in heavily pretreated pts across multiple advanced solid tumors with homozygous MTAP-del. Here, we report results of exploratory PD analyses of PRMT5 inhibition with BMS-986504 in CA240-0007. Methods: Pts with advanced, unresectable or metastatic solid tumors with homozygous MTAP-del received BMS-986504 (50 to 800 mg) in 3-wk cycles. Symmetric dimethylarginine (SDMA) and intron retention are known PD BMs of PRMT5 inhibition. Therefore, PD effects of BMS-986504 were assessed via changes in plasma and tumor SDMA levels (mass spec and IHC), intron retention, and gene expression (RNASeq) based on samples collected at baseline (BL) and cycle 2 day 1 (C2D1). Additional analyses correlating efficacy outcomes with PD results and select mutations at BL were performed in clinically evaluable pts as of 19-SEP-24. Results: Robust PD modulation of the PRMT5 pathway was observed with BMS-986504. Among pts with matched samples (n = 63), median plasma SDMA levels were reduced by 56% from BL (122.6 ng/mL) to C2D1 (53.8 ng/mL). There were dose-dependent reductions in median plasma SDMA with the greatest reductions at 400 mg QD (59.7% [n = 20]), 400 mg BID (61.9% [n = 9]) and 600 mg QD (59.1% [n = 14]). These PD effects were corroborated in the tumor. Median tumor SDMA levels decreased from an HScore of 285 at BL to 0 at C2D1. Consistent with the SDMA decreases, increased intron retention was observed in 9/11 pts with matched samples. BMS-986504 led to downregulation of several gene pathways including DNA repair and mitotic spindle formation, and MYC and E2F targets, as assessed by RNASeq. There was no significant change in expression of MAT2A, PRMT5, or other PRMT genes, suggesting a lack of compensation for PRMT5 inhibition through these genes. Responses were observed with BMS-986504 across EGFR, KRAS, and TP53 mutation subgroups. Additional correlative analyses among BMs and efficacy outcomes will be presented. Conclusions: BMS-986504 demonstrated robust PD effects across multiple doses and solid tumors which is consistent with the proposed mechanism of action. There was a trend of increasing plasma SDMA reduction across doses, with the greatest reductions observed at 400 mg QD and above. Together these results support further investigation of BMS-986504 at 400 mg QD and higher doses as a potential first-in-class synthetic lethal Tx option in pts with advanced solid tumors with MTAP-del. Citation Format: Jordi Rodón, Tyler Simpson, Ben George, Pasi A. Jänne, Kathryn C. Arbour, Konstantinos Leventakos, Kyriakos P. Papadopoulos, Melissa L. Johnson, Alexander I. Spira, Cesar A. Perez, Hani M. Babiker, Richard Zuniga, Candace L. Haddox, Tapsi Kumar, Yidi Qin, Wen-Chi Chou, Peter Olson, Kenna Anderes, Alice Wozniak, Curtis Chin, Ming Lei, Jason T. Henry. Pharmacodynamic (PD) and exploratory biomarker (BM) analysis of the PRMT5 inhibitor BMS-986504 in patients (pts) with advanced solid tumors with homozygous MTAP deletion (MTAP-del) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_2):Abstract nr CT079.

2526 Background: Tumor necrosis factor receptor-2 (TNFR2) is expressed on effector CD8+, CD4+, and regulatory T (Treg) cells, natural killer (NK) cells, and myeloid cells. Activation of TNFR2 is anticipated to yield effective anti-tumor immunity by stimulating T-cell and NK-cell activation and proliferation in the tumor microenvironment. HFB200301 is a first-in-class anti-TNFR2 agonistic monoclonal antibody that triggers both innate and adaptive immune stimulation by binding to a specific epitope on TNFR2. We report initial results of an ongoing Phase I dose escalation, multicenter study (NCT05238883) of HFB200301 in monotherapy and in combination with tislelizumab (TIS) in patients (pts) with advanced refractory solid tumors. Methods: A Phase I trial designed to evaluate the safety, pharmacokinetics (PK), pharmacodynamics (PD), and initial efficacy of HFB200301 in monotherapy and in combination with TIS. Eligible pts, ≥18 years with an ECOG PS 0-1 and advanced solid tumors, will be enrolled in dose escalation at 5 different dose cohorts in monotherapy (Q4W), 3 different dose cohorts in combination with TIS (Q4W), or in dose expansion following determination of safety. Radiographic response is assessed every 8 weeks. Results: A total of 39 pts have been enrolled, 27 pts in monotherapy and 12 pts in combination. All pts received prior systemic therapy (median 2, range 1-4); 23 pts (59%) had prior checkpoint inhibitor treatment. No dose limiting toxicities were observed in either the monotherapy or combination arms. Treatment-related adverse events (TRAEs) occurred in 44% of monotherapy and in 50% of combination pts, with pruritis (11%), tremor (7%), fatigue (7%), asthenia (7%) and nausea (7%) being the most common TRAEs. No ≥ Grade 3 TRAEs were reported, and there were no drug discontinuations due to TRAEs. Preliminary HFB200301 PK analysis demonstrated non-linear clearance of HFB200301, with dose-proportional maximum concentration [Cmax], achieving sufficient exposures for peripheral target engagement in all tested doses. Emerging PD data demonstrates evidence of immune activation and expansion of CD8+ T cells, but not Tregs, in the tumor microenvironment and peripheral blood. Single cell RNAseq analysis of peripheral blood mononuclear cells demonstrated PD modulation in TNFR2 positive immune cell types post-HFB200301 treatment. Early response evaluation reveals ongoing durable clinical responses (> 6 months) in a PD-L1+ pleural mesothelioma pt and an EBV+ gastric cancer pt from combination cohorts. Conclusions: HFB200301 demonstrates a favorable safety profile, dose-dependent PK, with PD and preliminary clinical activity in monotherapy and in combination with TIS in pts with heavily pre-treated refractory solid tumors. Clinical trial information: NCT05238883 .

PURPOSE KRAS is the most commonly mutated driver oncogene in non–small cell lung cancer (NSCLC). Sotorasib and adagrasib, KRAS G12C inhibitors, have been granted accelerated US approval; however, hepatotoxicity is a common side effect with higher rates in patients treated with sotorasib proximal to checkpoint inhibitor (CPI) therapy. The aim of this study was to assess the feasibility and safety of adagrasib after discontinuation of sotorasib because of treatment-related grade 3 hepatotoxicity through real-world and clinical cases. METHODS Medical records from five patients treated in real-world settings were retrospectively reviewed. Patients had locally advanced or metastatic KRAS G12C -mutated NSCLC and received adagrasib after sotorasib in the absence of extracranial disease progression. Additional data were collected for 12 patients with KRAS G12C -mutated NSCLC enrolled in a phase Ib cohort of the KRYSTAL-1 study and previously treated with sotorasib. The end points associated with both drugs included timing and severity of hepatotoxicity, best overall response, and duration of therapy. RESULTS All patients were treated with CPIs followed by sotorasib (initiated 0-64 days after CPI). All five real-world patients experienced hepatotoxicity with sotorasib that led to treatment discontinuation, whereas none experienced treatment-related hepatotoxicity with subsequent adagrasib treatment. Three patients from KRYSTAL-1 transitioned from sotorasib to adagrasib because of hepatotoxicity; one experienced grade 3 ALT elevation on adagrasib that resolved with therapy interruption and dose reduction. CONCLUSION Adagrasib may have a distinct hepatotoxicity profile from sotorasib and is more easily combined with CPIs either sequentially or concurrently. These differences may be used to inform clinical decisions regarding an initial KRAS G12C inhibitor for patients who recently discontinued a CPI or experience hepatotoxicity on sotorasib.