BC3195, a novel ADC targeting CDH3: Preliminary results of a first-in-human phase I study in patients with advanced solid malignancies.

e15008 Background: Cadherin-3 (CDH3), a calcium-dependent cell-cell adhesion glycoprotein, is overexpressed on lung, breast, ovarian, colorectal, pancreatic, head and neck and other malignancies, but with negligible expression on nonmalignant tissues, and associated with cancer aggressiveness, invasiveness, and poor prognosis. BC3195 is known as the only antibody drug conjugate (ADC) in clinical stage, targeting CDH3 with payload of monomethyl auristatin E (MMAE). Methods: A phase I, open-label, first in human study to evaluate the safety, tolerability, PK, and preliminary antitumor activity of BC3195 is being performed in subjects with advanced solid malignancies. Disease assessments are performed every 6 weeks using RECIST v1.1. BC3195 is administered as 1 hour (h) IV infusion every 3 weeks. An evaluation of seven dose levels is planned: 0.3, 0.6, 1.2, 2.4, 3.0 and 3.6 mg/kg with a BOIN design guiding dose escalation. Results: Up to January 1 st , 2024, nine patients (median age, 59; male, 56%) have been enrolled and treated with BC3195, with 3 patients each in the 0.3, 0.6 and 1.2 mg/kg dose cohorts. No DLT was observed across all the 3 dose cohorts. Treatment emergent adverse events (TEAEs) occurring in ≥3 patients included: aspartate aminotransferase increased (5/9, 55.6%), conjugated bilirubin increased (5/9, 55.6%), triglycerides increased (4/9, 44%), uric acid increased (3/9, 33.3%), heart rate increased (3/9, 33%), and hypoalbuminemia (5/9, 55.6%), cough (4/9, 44.4%), hyponatraemia (4/9, 44.4%), anemia (4/9, 44.4%), asthenia (3/9, 33.3%), rash (3/9, 33.3%), vomiting (3/9, 33.3%) and back pain (3/9, 33.3%). Two subjects experienced ≥ Grade 3 TEAEs unrelated to study drug. Six subjects were evaluable for tumor assessment, and 3 subjects (3/6, 50%) show stable disease (SD) as the best response (2 subjects with target lesion reduction). PK results demonstrated that exposure for the ADC and total antibody (TA) increased with dose, the relationship between AUC 0-last and dose was greater than dose-proportional, while C max was linear. Free MMAE was highest at the 1.2 mg/kg dose level. Median T max values for ADC and TA were 1 h (end of infusion), and median T max for free MMAE was 25-169 h. In addition, elimination t 1/2 values averaged 27-48 h, 31-68 h and 63-76 h for the ADC, TA, and MMAE, respectively. Conclusions: BC3195 exhibited favorable safety profile and PK characteristics up to 1.2mg/kg. Given BC31095’s safety and PK behavior, as well as preliminary activity at the 0.6 mg/kg dose level, patient enrollment at higher dose levels is ongoing. Clinical trial information: NCT05957471 .