402O - Preliminary results of phase II study to evaluate safety and efficacy of combination pucotenlimab with epidermal growth factor receptor-ADC (EGFR-ADC) MRG003 in recurrent or metastatic nasopharyngeal carcinoma (R/M-NPC)

Background

As an epidermal growth factor receptor-ADC (EGFR-ADC), MRG003, in combination of pucotenlimab (HX008) had shown good tolerability and promising anti-tumor activity in EGFR-positive solid tumors in phase I study. Here we reported the initial results from NPC cohort from the phase II part of HX008/MRG003-C001 (NCT05688605).

Methods

In this Phase II part, pts with R/M−NPC who had failed first-line platinum-based therapy were enrolled to receive 3.0 mg/kg HX008 combined with 2.0 mg/kg MRG003 every 3 weeks. The primary endpoint was objective response rate (ORR) in full analysis set (FAS) assessed by investigators according to RECIST v.1.1. The secondary endpoint included progression-free survival (PFS), overall survival (OS), duration of response (DoR), and safety.

Results

As of 30 June 2024 (cut-off date), 30 pts were enrolled in this study with a median age of 50 (32,64), and 21 pts (70.0%) were male. 14 (46.7%) pts were ECOG PS 0. 29 (96.7%) pts had failed from anti-PD-(L)1 treatment. A total of 30 pts were assessed, the median follow-up time was 4.2 months (3.6-5.5). 2 pts achieved CR, 18 pts achieved PR, and 8 pts achieved SD. All responses were confirmed, cORR and DCR were 66.7% (95%CI: 59.7, 73.7%) and 93.3% (95%CI: 91.9, 94.8), respectively. PFS and DoR were immature, with 6-month PFS rate of 76.2% (95%CI: 50.5, 89.7) and 6-month DoR rate of 83.3% (95%CI: 27.3, 97.5), respectively. The most commonly reported treatment-related adverse events (TRAEs) included pruritus (70.0%), rash (53.3%), anemia (50.0%), and alopecia (43.3%). Grade 3-4 TRAEs occurred in 7 pts (23.3%) and were mainly pneumonia (6.7%) and patients recovered to resume therapy. The incidence of SAE was 10.0% (3pts). There were no TRAEs leading to discontinuation of the therapy, or to death.

Conclusions

MRG003 in combination with HX008 demonstrated promising efficacy results and good safety profile in this trial. It may provide an efficacious salvage treatment option for R/M-NPC pts who had failed anti-PD-(L)1 and platinum-based therapy. Further follow-up is ongoing.

Clinical trial identification

NCT05688605.

Editorial acknowledgement

Legal entity responsible for the study

Shanghai Miracogen Inc.

Funding

Shanghai Miracogen Inc.

Disclosure

All authors have declared no conflicts of interest.