MRUS Stock: Why It Substantially Increased Today

By Amit Chowdhry ● Oct 7, 2021
  • The stock price Merus NV (NASDAQ: MRUS) increased by over 35% today. This is why it happened.

The stock price Merus NV (NASDAQ: MRUS) – a clinical-stage oncology company developing innovative, full-length multispecific antibodies (Biclonics and Triclonics) – increased by over 35% today. Investors responded positively to Merus presenting clinical data on MCLA-158, including clinical responses observed in advanced head and neck squamous cell carcinoma (HNSCC) and preclinical data on zenocutuzumab (Zeno) at the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics.

MCLA-158 (petosemtamab)

The reported data are from the ongoing phase 1 dose expansion cohort that is investigating the safety, tolerability, and anti-tumor activity of MCLA-158 monotherapy in advanced HNSCC.

The observations in the presentation include:

— The enrollment of 10 patients with advanced HNSCC, as of the safety and efficacy data cutoff date of August 9, 2021 with median age of 65 (range 50-77) years, and who were treated with a median of 2 lines of prior therapy.

— 7 patients were evaluable for an interim efficacy analysis by investigator assessment (3 patients were enrolled <8 weeks from the cutoff date).

— 3 of 7 patients achieved partial responses, with one achieving complete response after the data cutoff date. And tumor reduction was observed in all 7 patients.

— The safety profile of MCLA-158 was based on 29 patients with advanced solid tumors who were treated at 1500 mg every two weeks across the phase 1 trial.

a.) The most frequent adverse events (AEs) were infusion related reactions; 72% any grade, 7% grade ≥ 3.

b.) Mild to moderate skin toxicity (3% grade ≥3).

The company is planning its next update on the MCLA-158 trial in 2022.


The observations in the preclinical presentation include:

— The bispecific HER2/HER3 antibody Zeno blocked cell growth 100 fold more potently than the bivalent HER3 antibody derived from Zeno, in an NRG1 driven growth assay.

— Zeno potently blocked NRG1-fusion mediated downstream signaling and growth in vitro and in vivo.

— Zeno induced both antibody-dependent cellular cytotoxicity (ADCC) and antibody-dependent cellular phagocytosis (ADCP) mediated killing of cancer cells in a dose-dependent manner.

— As of September 1, 2021 more than 80 patients with NRG1 fusion cancers have been treated with Zeno monotherapy in our phase 1/2 eNRGy trial and Early Access Program.


“We are encouraged by the early evidence of clinical activity of MCLA-158 in patients with advanced, previously treated HNSCC, further validating the potential of our Biclonics® platform. With Zeno, our preclinical research continues to reinforce the mechanisms by which Zeno is capable of potently inhibiting the growth of NRG1 fusion cancers.”

— Dr. Andrew Joe, Chief Medical Officer at Merus

Disclaimer: This content is intended for informational purposes. Before making any investment, you should do your own analysis.