Supplementary Table S1 shows cytotoxicity of exatecan compared to DXd. Supplementary Table S2 shows selected hematologic parameters and biochemical parameters from the repeat-dose administration of exatecan mesylate studies in rats. Supplementary Table S3 shows in vitro ADC stability study of total antibody, ADC and free payload. Supplementary Table S4 shows pharmacokinetic parameters of total antibody, ADC and free payload. Supplementary Table S5 shows ADC (T: T-1000-e; D: DS-8201a) internalization rate on cell lines with different HER2 expression level. Supplementary Table S6 shows correlation of exatecan release and target expression. Supplementary Table S7 shows In vitro cytotoxicicity of HER-targeting MTX-1000, TROP2 targeting MTX-132 and HER3-targeting Patritumab-T1000-exatecan and their counterpart DXd-ADC.
ARTICLE ABSTRACT
Antibody–drug conjugates (ADC) using DNA topoisomerase I inhibitor DXd/SN-38 have transformed cancer treatment, yet more effective ADCs are needed for overcoming resistance. We have designed an ADC class using a novel self-immolative T moiety for traceless conjugation and release of exatecan, a more potent topoisomerase I inhibitor with less sensitivity to multidrug resistance (MDR). Characterized by enhanced therapeutic indices, higher stability, and improved intratumoral pharmacodynamic response, antibody–T moiety–exatecan conjugates targeting HER2, HER3, and TROP2 overcome the intrinsic or treatment resistance of equivalent DXd/SN-38 ADCs in low-target-expression, large, and MDR+ tumors. T moiety–exatecan ADCs display durable antitumor activity in patient-derived xenograft and organoid models representative of unmet clinical needs, including EGFR ex19del/T790M/C797S triple-mutation lung cancer and BRAF/KRAS–TP53 double-mutant colon cancer, and show synergy with PARP/ATR inhibitor and anti–PD-1 treatment. High tolerability of the T moiety–exatecan ADC class in nonhuman primates supports its potential to expand the responding patient population and tumor types beyond current ADCs.
ADCs combining a novel self-immolative moiety and topoisomerase I inhibitor exatecan as payload show deep and durable response in low-target-expressing and MDR+ tumors resistant to DXd/SN-38 ADCs without increasing toxicity. This new class of ADCs has the potential to benefit an additional patient population beyond current options.See related commentary by Gupta et al., p. 817.This article is highlighted in the In This Issue feature, p. 799
