Merus' Petosemtamab Abstract Hits Upside Scenario For Overall Response Rate, Duration Of Response: Analyst - Merus (NASDAQ:MRUS)

Merus N.V. MRUS announced the publication of an abstract for a poster presentation of early clinical data on the bispecific antibody petosemtamab in advanced gastric/esophageal adenocarcinoma (GEA) at the American Association for Cancer Research (AACR) Annual Meeting.
The company has decided to pause further clinical exploration of the GEA cancer cohort.
Petosemtamab has demonstrated promising clinical activity among pretreated gastric/esophageal adenocarcinoma (GEA) patients, Merus said.
Given the strong clinical activity observed in this cohort, the company plans to prioritize investigating petosemtamab in head and neck squamous cell carcinoma.
As of an October 24, 2022, data cutoff date, 14 previously treated GEA patients were treated with petosemtamab 1500 mg (IV) every two weeks.
One patient with tumor epidermal growth factor receptor protein overexpression and gene copy number amplification showed a confirmed sustained partial response (67% tumor reduction; response ongoing after 24 cycles).
Three patients had stable disease, with 2%, 17%, and 40% tumor reductions.
The company also published the first look at updated data from the dose-expansion portion of Phase 1/2 study of petosemtamab in patients with head and neck squamous cell carcinoma (HNSCC).
As of the data cutoff in the abstract of November 28, 2022, 42 patients were evaluable for response, with an ORR of 35.7% reported (15/42), including one complete response (CR) and two unconfirmed partial responses (uPRs, treatment ongoing).
15 patients had stable disease and a disease control rate of 71.4%
The median duration of response at the cutoff was six months, and the median progression-free survival was 5.0 months.
William Blair writes that the response rate comes in well above double the rate of monotherapy response rate (13%) observed with Eli Lilly And Co's LLY Erbitux (cetuximab).
The analyst writes that the results will increase confidence in the clinical profile of petosemtamab.
Price Action: MRUS shares closed higher by 11.40% at $20.75 on Friday.

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