Thread by @StephenVLiu

#ESMO20 Dr. @HelenaYu923 presents data on patritumab deruxtecan (U3-1402), a HER3-ADC for patients with #EGFR mutant NSCLC. #LCSM @OncoAlert

#ESMO20 HER3 is expressed in 80% of #EGFR mutant NSCLC hence this ADC approach. Patritumab is an ADC with HER3 Ab linked to a topoisomerase I payload. Here, data from escalation (n=12) and expansion (n=45) in EGFR+ NSCLC after TKI (expansion was post chemo as well). #LCSM

#ESMO20 Median follow up was 5 months across the study. Median of 4 prior lines of therapy and most patients (86%) had prior osimertinib. Brain metastases present in almost half of patients. No HER3 selection but majority did have expression. #LCSM

#ESMO20 In 49 evaluable patients, 1 CR, 13 confirmed PR, 3 unconfirmed PR. Most with some reduction. Activity seen across various TKI resistance mechanisms including C797S, MET, KRAS, HER2, BRAF. #LCSM @OncoAlert

#ESMO20 The ORR was 25% but does not include several unconfirmed responses. Time to response was 2 months, DOR 6.9 months. Notable myelosuppression but did not seem to lead to discontinuation. 3 cases of related ILD. Most toxicities managed with dose reduction. #LCSM