This study was designed to evaluate the efficacy and safety of MRG003 in R/M SCCHN….The immunohistochemistry detection of EGFR expression was performed in 65 pts, and 62 pts (95.4%) were EGFR-positive….At the data cutoff, the ORR was 30.6% in all EGFR-positive pts.

In phase 1a, 1 patient (5%) achieved a partial response, and 5 (23%) achieved stable disease. In phase 1b, 8 patients (21%) achieved a confirmed partial response, and 12 (31%) achieved stable disease. The objective response rates for SCCHN, NPC, and CRC were 40%, 44%, and 0%, and the disease control rates were 100%, 89%, and 25%, respectively....The findings of this nonrandomized clinical trial suggest that MRG003 showed a manageable safety profile and promising antitumor activity in patients with EGFR-positive NPC and SCCHN.

...a total of 39 pts with CRC (12), SCCHN (13), and NPC (14) were enrolled in Ph Ib with pre-screening of EGFR by IHC….Among 18 of 22 pts who had tumor evaluation in Ph Ia, the ORR was 6% and DCR was 33%; Among 27 of 39 pts evaluable for efficacy in Ph Ib, the BOR was 11 PR (8 confirmed) and 9 SD, the ORR was 30% and DCR was 63%. The ORR was 40% and DCR was 80% for SCCHN, and the ORR was 44% and DCR was 78% for NPC.

Among these 9 EGFR positive pts, one with NPC in the 2.5 mg/kg cohort had partial response, four had stable disease (one with H&N in the 1.5 mg/kg, one each with NPC and H&N in the 2.0 mg/kg, and one with EC in the 2.5 mg/kg cohorts). The disease control rate (DCR) at doses ≥1.5 mg/kg was 100% for the EGFR positive pts....The dose escalation study of MRG003 showed manageable safety profiles and encouraging preliminary antitumor activity in pts with EGFR-positive solid tumors. MRG003 is currently being evaluated as a single agent in phase I dose expansion cohorts to further assess safety, PK, and antitumor activity.