TROPION-PanTumor01: Dose analysis of the TROP2-directed antibody-drug conjugate (ADC) datopotamab deruxtecan (Dato-DXd, DS-1062) for the treatment (Tx) of advanced or metastatic non-small cell lung cancer (NSCLC).

9058 Background: Datopotamab deruxtecan (Dato-DXd; DS-1062) is an ADC composed of a humanized anti-TROP2 IgG1 monoclonal antibody conjugated to a topoisomerase I inhibitor via a tetrapeptide-based cleavable linker. Methods: TROPION-PanTumor01 (NCT03401385) is a multicenter dose-escalation/expansion study evaluating Dato-DXd administered Q3W in patients (pts) with advanced NSCLC (since expanded to other tumor types, excluded from this analysis). Efficacy and safety were evaluated in 175 pts for dose analysis. Pharmacometric analyses (population pharmacokinetics [popPK] and exposure-response modeling) were conducted across doses to inform dose selection for further development. Results: At data cutoff (Sept 4, 2020), median follow-up was 7.4 mo (range, 0.10-21.7 mo). Select all-grade TEAEs were 1.5- to 2-fold higher in the 8 mg/kg vs 4 and 6 mg/kg cohorts: vomiting (34% vs 12% and 18%), anemia (28% vs 4% and 16%), diarrhea (20% vs 6% and 11%), and mucositis (29% vs 6% and 13%). Rates of grade ≥3 drug-related TEAEs and serious drug-related TEAEs were ≥2-fold higher with the 8 mg/kg dose (n = 80; 34% and 20%) relative to the 4 mg/kg (n = 50; 10% and 8%) and 6 mg/kg (n = 45; 16% and 9%) doses. Rates of drug-related interstitial lung disease (ILD), as determined by an independent adjudication committee, were higher in the 8 mg/kg cohort (15% vs 2% and 2% in the 4 and 6 mg/kg cohorts); 3 pts in the 8 mg/kg cohort experienced grade 5 ILD. Dose interruptions and reductions due to TEAEs increased with dose (4 mg/kg: 4% and 2%; 6 mg/kg: 20% and 9%; 8 mg/kg: 20% and 31%). More pts in the 8 mg/kg cohort discontinued Tx early due to AEs (15%) compared with those in the 4 mg/kg (4%) and 6 mg/kg (7%) cohorts. ORRs determined by blinded independent central review were similar: 8 mg/kg, 25% (20/80); 6 mg/kg, 21% (8/39); and 4 mg/kg, 23% (9/40). Preliminary median PFS (95% CI) was 5.4 mo (4.1-7.1 mo) in the 8 mg/kg cohort, 8.2 mo (1.5-11.8 mo) in the 6 mg/kg cohort, and 4.3 mo (2.0 mo-NE) in the 4 mg/kg cohort. PFS was limited by early censoring due to immature duration of follow-up, with the majority of pts having ≤3 mo of follow-up in the 4 (66%) and 6 mg/kg (67%) cohorts vs 8 mg/kg (46%) cohort. In pharmacometric analyses, tumor-size change from baseline and probability of complete response/partial response positively correlated with exposure (AUC) of Dato-DXd. Incidences of dose reduction and grade ≥2 stomatitis/mucositis were also positively correlated with exposure; projected probabilities in a virtual population bootstrapped from pts with NSCLC in the popPK data confirmed these trends. Updated results will be presented. Conclusions: A Dato-DXd dose of 6 mg/kg was selected for the randomized, phase 3, TROPION-Lung01 trial (NCT04656652) based on better tolerance and improved efficacy, including a trend toward increased PFS. Clinical trial information: NCT03401385.