Marinis, Filippo de

8513 Background: The MET pathway is a known mediator of EGFR-TKI resistance and represents a therapeutic vulnerability to select MET-TKIs. Savo is an oral, highly selective MET-TKI that, when combined with osi, has the potential to overcome MET-driven resistance after progressive disease (PD) on osi. The Phase 2 SAVANNAH study has demonstrated clinically meaningful activity with the combination of savo + osi in patients (pts) with EGFR-mutated (EGFRm) advanced NSCLC and MET overexpression/amplification (NCT03778229). Isolating the efficacy of savo in the use of savo + osi is a key question for this combination. Methods: A subset of SAVANNAH included eligible pts who had EGFRm advanced NSCLC with MET overexpression (IHC 3+ intensity in ≥90% of tumor cells [IHC3+/≥90%]) and/or amplification (≥10 MET gene copies by FISH [FISH10+]) after PD on first-line (1L) osi; asymptomatic stable brain metastases (treated/untreated) were allowed. Pts were randomized 2:1 (double-blind) to savo 300 mg BID + osi 80 mg QD, or savo 300 mg BID + PBO (stratified by investigator [INV] assessed baseline [BL] brain metastases [yes/no]), until INV-assessed PD per RECIST 1.1. Brain imaging occurred at BL and PD; pts with brain metastases were re-imaged at each tumor assessment to PD. Endpoints included objective response rate (ORR), duration of response (DoR), and progression-free survival (PFS) by BICR and INV; CNS PFS, and presence/absence of CNS lesions at PD by BICR. Results: Overall, 73 pts were randomized (savo + osi n=48; savo + PBO n=25). At BL, median age: 67 vs 65 years, female: 73% vs 64%, White: 73% vs 52% in the savo + osi and savo + PBO arms, respectively. Efficacy outcomes (ORR, DoR, and PFS) were higher with savo + osi than savo + PBO (Table). CNS PFS events by CNS BICR occurred in 5/14 (36% savo + osi) and 2/4 pts (50% savo + PBO). In pts without BL brain metastases, none of the 13 pts (savo + osi) with RECIST PD by BICR had a new CNS lesion; 6/11 pts in the savo + PBO arm developed a new CNS lesion. Conclusions: In EGFRm advanced NSCLC with MET IHC3+/≥90% and/or FISH10+ status after PD on 1L osi, efficacy of savo 300 mg BID + osi was numerically greater than savo + PBO and showed promising CNS activity. To date, this is one of the largest randomized data sets presented evaluating an oral MET-TKI in EGFRm NSCLC. Efficacy findings from SAVANNAH suggest that targeting both EGFR and MET is key and support further investigation of savo + osi and CNS activity in the Phase 3 SAFFRON study. Clinical trial information: NCT03778229 . Assessment Savo + osi (n=48) Savo + placebo (n=25) ORR, % (95% CI) BICR 58 (43, 72) 16 (5, 36) INV 54 (39, 69) 24 (9, 45) DoR, mo, median (95% CI) BICR 11.8 (6.0, NC) 4.5 (2.6, NC) INV 8.0 (4.9, 11.7) 4.2 (2.6, NC) PFS, mo, median (95% CI) BICR 8.3 (5.8, 15.1) 3.6 (1.4, 5.7) INV 7.6 (5.6, 11.0) 2.7 (1.4, 4.1) BICR, blinded independent central review; CI, confidence interval; mo, months; NC, not calculable.

Abstract Background: Savo is an oral, potent and highly selective MET-TKI. In the Phase 2 SAVANNAH study (NCT03778229), savo + osi had a high rate of durable responses in pts with EGFRm advanced NSCLC and high MET OverExp and/or Amp levels. Early clearance of plasma EGFRm may predict outcomes. We report an exploratory analysis of plasma EGFRm clearance and its association with MET tissue biomarker status, ORR and PFS. Methods: Pts with EGFRm advanced NSCLC and MET OverExp and/or Amp with PD on 1L+ osi received savo 300 mg QD, 300 mg BID or 600 mg QD + osi 80 mg QD. MET OverExp/Amp was centrally confirmed (by IHC [Roche], 3+ intensity in ≥50% of tumor cells [MET IHC3+/≥50%]; by FISH [Abbott Molecular], MET gene copy number ≥5 or MET:CEP7 ratio ≥2 [FISH5+], or at higher thresholds of MET IHC3+/≥90% or FISH10+). Baseline (BL) and Wk 3 plasma EGFRm (Ex19del/L858R) were analyzed by ddPCR (Biodesix) as an estimate of tumor burden. MET Amp was not monitored in ctDNA due to low detection sensitivity. Clearance was defined as undetected EGFRm ctDNA at Wk 3, when detected at BL. PFS was investigator-assessed (RECIST 1.1). DCO: Aug 23, 2024. Results: Of 344 pts with evaluable BL ctDNA, 259 (75%) had detected EGFRm ctDNA. Of these, 225 had evaluable ctDNA at Wk 3 (82 [36%] had EGFRm clearance at Wk 3). Confirmed ORR was higher in pts with EGFRm Wk 3 clearance (56/82; 68%) vs non-clearance (38/143; 27%). PFS was longer in pts with vs without EGFRm clearance at Wk 3 (Table). Across all pts evaluable for ctDNA at Wk 3, clearance rates were higher in pts with vs without high MET (69/162 [43%] vs 13/63 [21%]; odds ratio [95% CI] 0.35 [0.16, 0.72]). Similar results were seen in the savo 300 mg QD + osi subgroup. Conclusions: In SAVANNAH, among pts with detected EGFRm ctDNA at BL, clearance at Wk 3 was associated with improved ORR and PFS. Plasma EGFRm clearance at Wk 3 is enriched in pts with MET IHC3+/≥90% or FISH10+ status, consistent with improved efficacy in this biomarker subgroup. Citation Format: Jonathan W. Riess, Filippo de Marinis, Benjamin Levy, Tae Min Kim, Laura Bonanno, Quincy Chu, Marcello Tiseo, Adrian Sacher, Silvia Novello, Christina Baik, Lyudmila Bazhenova, Jacques Cadranel, Giulio Metro, Cheng-Ta Yang, Tsung-Ying Yang, Gee-Chen Chang, Konstantinos Leventakos, Lorenzo Livi, James Chih-Hsin Yang, Lecia V. Sequist, John Argue, Wanning Xu, Aleksandra Markovets, Ryan Hartmaier, Myung-Ju Ahn. SAVANNAH: Clearance of plasma EGFRm in patients with EGFRm MET-overexpressed (OverExp) and/or -amplified (Amp) NSCLC post-osimertinib (osi) treated with savolitinib (savo) + osi [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 LB416.

ImportanceArginine deprivation using ADI-PEG20 (pegargiminase) combined with chemotherapy is untested in a randomized study among patients with cancer. ATOMIC-Meso (ADI-PEG20 Targeting of Malignancies Induces Cytotoxicity-Mesothelioma) is a pivotal trial comparing standard first-line chemotherapy plus pegargiminase or placebo in patients with nonepithelioid pleural mesothelioma.ObjectiveTo determine the effect of pegargiminase-based chemotherapy on survival in nonepithelioid pleural mesothelioma, an arginine-auxotrophic tumor.Design, Setting, and ParticipantsThis was a phase 2-3, double-blind randomized clinical trial conducted at 43 centers in 5 countries that included patients with chemotherapy-naive nonepithelioid pleural mesothelioma from August 1, 2017, to August 15, 2021, with at least 12 months’ follow-up. Final follow-up was on August 15, 2022. Data analysis was performed from March 2018 to June 2023.InterventionPatients were randomly assigned (1:1) to receive weekly intramuscular pegargiminase (36.8 mg/m2) or placebo. All patients received intravenous pemetrexed (500 mg/m2) and platinum (75-mg/m2 cisplatin or carboplatin area under the curve 5) chemotherapy every 3 weeks up to 6 cycles. Pegargiminase or placebo was continued until progression, toxicity, or 24 months.Main Outcomes and MeasuresThe primary end point was overall survival, and secondary end points were progression-free survival and safety. Response rate by blinded independent central review was assessed in the phase 2 portion only.ResultsAmong 249 randomized patients (mean [SD] age, 69.5 [7.9] years; 43 female individuals [17.3%] and 206 male individuals [82.7%]), all were included in the analysis. The median overall survival was 9.3 months (95% CI, 7.9-11.8 months) with pegargiminase-chemotherapy as compared with 7.7 months (95% CI, 6.1-9.5 months) with placebo-chemotherapy (hazard ratio [HR] for death, 0.71; 95% CI, 0.55-0.93; P = .02). The median progression-free survival was 6.2 months (95% CI, 5.8-7.4 months) with pegargiminase-chemotherapy as compared with 5.6 months (95% CI, 4.1-5.9 months) with placebo-chemotherapy (HR, 0.65; 95% CI, 0.46-0.90; P = .02). Grade 3 to 4 adverse events with pegargiminase occurred in 36 patients (28.8%) and with placebo in 21 patients (16.9%); drug hypersensitivity and skin reactions occurred in the experimental arm in 3 patients (2.4%) and 2 patients (1.6%), respectively, and none in the placebo arm. Rates of poststudy treatments were comparable in both arms (57 patients [45.6%] with pegargiminase vs 58 patients [46.8%] with placebo).Conclusions and RelevanceIn this randomized clinical trial of arginine depletion with pegargiminase plus chemotherapy, survival was extended beyond standard chemotherapy with a favorable safety profile in patients with nonepithelioid pleural mesothelioma. Pegargiminase-based chemotherapy as a novel antimetabolite strategy for mesothelioma validates wider clinical testing in oncology.Trial RegistrationClinicalTrials.gov Identifier: NCT02709512