Merus Announces Business Update Conference Call

On October 15, 2023 Merus N.V. (Nasdaq: MRUS) (Merus, the Company, we, or our), a clinical-stage oncology company developing innovative, full-length multispecific antibodies (Biclonics and Triclonics), reported that it will host a conference call to discuss a business update on Monday, October 16, 2023 at 7:30 a.m. ET (Press release, Merus, OCT 15, 2023, View Source [SID1234635976]).

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Zenocutuzumab (Zeno or MCLA-128: HER2 x HER3 Biclonics): NRG1 fusion (NRG1+) cancer and other solid tumors

Today two abstracts were published on the European Society for Medical Oncology Congress (ESMO) (Free ESMO Whitepaper) 2023 website. The abstracts highlight updated interim clinical data from the ongoing phase 1/2 eNRGy trial and Early Access Program (EAP) of the bispecific antibody zenocutuzumab (Zeno) in patients with neuregulin 1 fusion (NRG1+) cancer. The Principal Investigator of the eNRGy trial, Dr. Alison Schram of Memorial Sloan-Kettering Cancer Center will present a mini oral session on NRG1+ NSCLC. The ESMO (Free ESMO Whitepaper) Congress 2023 will take place in Madrid, Spain October 20-24, 2023.

"Zeno continues to show remarkably consistent efficacy over time, with robust and durable responses in these difficult-to-treat indications," said Dr. Andrew Joe, Chief Medical Officer at Merus. "We recently met with the FDA in the context of our two breakthrough therapy designations and based on these productive and collaborative discussions, we believe we will have sufficient data for both NRG1+ NSCLC and NRG1+ PDAC in the first half of 2024 to support biologics license application submissions."

Interim data included in the abstracts are from the phase 1/2 eNRGy trial and EAP which are assessing the safety and anti-tumor activity of Zeno monotherapy in NRG1+ cancer. Updated data will be provided in the presentations to include additional patients as well as follow-up on safety and efficacy for the patients presented in the abstracts:

Mini Oral Presentation Title: Durable efficacy of zenocutuzumab, a HER2 x HER3 bispecific antibody, in advanced NRG1 fusion-positive (NRG1+) non-small cell lung cancer (NSCLC)

Observations in the abstract include:
As of a February 1, 2023 data cutoff date, 85 patients (pts) with NRG1+ NSCLC were enrolled. 64 pts with measurable disease were treated as of August 1, 2022 allowing for the potential for ≥ 6 months follow up and were evaluable for response
34% overall response rate (ORR) (95% CI, 23-47) by RECIST v1.1. per investigator assessment
78% of pts had target lesion reduction
12.9 months median duration of response (DOR), with responses ongoing in 50% of pts
Among the 85 pts enrolled, Grade ≥ 3 adverse events (AEs) irrespective of causality occurred in < 4% pts
Presentation Details:
Session Category: Mini oral session 1
Session: NSCLC, metastatic
Date: Saturday, October 21, 2023
Time: 9:35-9:40 CEST
Presentation #: 1315MO

Poster Presentation Title: Durable efficacy of zenocutuzumab, a HER2 x HER3 bispecific antibody, in advanced NRG1 fusion-positive (NRG1+) pancreatic ductal adenocarcinoma (PDAC)

Observations in the abstract include:
As of a February 1, 2023 data cutoff date, 38 pts with NRG1+ PDAC were enrolled. 27 pts with measurable disease were treated as of August 1, 2022 allowing for the potential for ≥ 6 months follow-up and were evaluable for response
44% ORR (95% CI, 26-65) by RECIST v1.1. per investigator assessment; including 1 complete response
81% of pts had target lesion reduction and 84% of pts had CA 19-9 decline of ≥ 50% from baseline
9.1 months median DOR, with responses ongoing in 33% of pts
Among the 38 pts enrolled, Grade ≥ 3 AEs irrespective of causality occurred in < 5% pts
Presentation Details:
Session: Poster Session
Date: Monday, October 23, 2023
Time: 9:00-17:00 CEST
Presentation #: 1618P

As full presentations become available at the ESMO (Free ESMO Whitepaper) Congress 2023, they will contemporaneously be available on the Merus website.

Merus is also evaluating Zeno in combination with androgen deprivation therapy (enzalutamide or abiraterone) in men with castration resistant prostate cancer, irrespective of NRG1+ status. Merus plans to provide initial clinical data in the second half of 2023.

Petosemtamab (MCLA-158: EGFR x LGR5 Biclonics): Solid Tumors

Merus plans to initiate the phase 3 clinical trial in mid-2024 to evaluate petosemtamab monotherapy in previously treated recurrent or metastatic head and neck squamous cell carcinoma (HNSCC). Earlier this year in a presentation at the American Association of Cancer Research Annual Meeting, interim clinical data in this indication, having a data cutoff date of February 1, 2023, demonstrated the high and durable efficacy of petosemtamab with a well-tolerated and manageable safety profile.

"We’re very excited to start enrolling the randomized phase 3 trial as we believe we have an opportunity to significantly improve the outcomes of patients with head and neck cancer," said Bill Lundberg, M.D., President, Chief Executive Officer of Merus. "Additionally, we are encouraged to report that among the initial patients dosed in the front-line combination of petosemtamab with Keytruda, the safety profile has been observed to be generally favorable with no dose limiting toxicities reported to date."

In the planned phase 3 trial, patients will be randomized to petosemtamab monotherapy or to investigators choice of single agent chemotherapy or cetuximab. Data regarding the INTERLINK-1 trial was released today ahead of the ESMO (Free ESMO Whitepaper) Congress 2023. Merus believes the clinical activity of cetuximab monotherapy in patients with recurrent or metastatic squamous cell carcinoma of the head and neck who received prior platinum-based chemotherapy and a PD-1/PD-L1 inhibitor, further supports the planned design of our phase 3 clinical trial.

Merus continues to enroll approximately 40 patients with previously treated HNSCC with petosemtamab monotherapy at the 1100 or 1500 mg dose levels to confirm a suitable dose for future potential randomized trials. Merus plans to share the clinical data from this cohort in 2024.

Merus also continues to enroll patients with previously untreated advanced PD-L1+ HNSCC with petosemtamab 1500 mg in combination with Keytruda. Initial safety data from this single arm cohort may support the initiation of a first-line registration trial with this combination. Merus plans to report initial interim safety and efficacy data from this cohort in the first half of 2024.

MCLA-129 (EGFR x c-MET Biclonics): Solid Tumors

Abstracts on the bispecific antibody MCLA-129 in NSCLC and in previously treated HNSCC were selected for presentation at the ESMO (Free ESMO Whitepaper) Asia Congress 2023 taking place in Singapore December 1-3, 2023.

Title: Efficacy and safety of MCLA-129, an EGFR x c-MET bispecific antibody, combined with osimertinib, as first-line therapy or after progression on osimertinib in non-small cell lung cancer (NSCLC)

Title: Efficacy and safety of MCLA-129, an anti-EGFR/c-MET bispecific antibody, in head and neck squamous cell cancer (HNSCC)

Merus is discontinuing the NSCLC with EGFR exon20 mutation cohort due to the competition in this niche market.

Company Conference Call and Webcast Information

Merus will hold a conference call and webcast for investors on October 16, 2023 at 7:30 a.m. ET. A replay will be available after the completion of the call in the Investors and Media section of our website for a limited time.

Date and Time: October 16, 2023 at 7:30 a.m. ET
Webcast link: Available on our website
Dial-in: Toll-Free: 1 (800) 715-9871 / International: 1 (646) 307-1963
Conference ID: 6064075