On June 4, 2021 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 interim efficacy data, as of an April 13, 2021 cutoff date, from the phase 1/2 eNRGy trial and Early Access Program (EAP) of bispecific antibody zenocutuzumab (Zeno) in patients with NRG1+ cancers, presented virtually by Lead Author, Dr. Alison Schram of Memorial Sloan Kettering Cancer Center (MSKCC) at the 2021 ASCO (Free ASCO Whitepaper) Annual Meeting (Press release, Merus, JUN 4, 2021, View Source [SID1234583576]).

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Dr. Andrew Joe, Chief Medical Officer at Merus said, "With confirmed partial responses observed in 42% of pancreatic cancer patients, and partial responses across several NRG1+ tumor types, we remain encouraged that Zeno has the potential to become a new treatment for patients with NRG1 fusion positive cancers. The data, including durability, continue to mature with 40% of evaluable patients remaining on therapy as of the data cutoff date."

Dr. Alison Schram said, "It is very exciting to witness the emergence of a potential new treatment for patients with NRG1 fusion-positive cancers, a population with unmet need. The data presented today are the first to clinically validate NRG1 fusions as drivers of cancer and show that Zeno is capable of blocking tumor growth in patients harboring these fusions."

The reported data are from the ongoing phase 1/2 eNRGy trial and EAP which are investigating the safety and anti-tumor activity of Zeno monotherapy in NRG1+ cancers. The eNRGy trial consists of three cohorts: NRG1+ pancreatic cancer; NRG1+ non-small cell lung cancer (NSCLC); and NRG1+ other solid tumors.

Key findings in the presentation include:

Enrollment of 61 patients with NRG1+ pancreatic, NSCLC, and other cancers.
47 patients were evaluable for primary analysis , with a median age of 56 (range 22-84), previously treated with a median of 2 lines of prior therapy.
45 patients were evaluable for response by local review with measurable disease and the opportunity for ≥ 1 post-baseline tumor assessment (two patients with non-measurable disease are included in the primary analysis of 47 patients, but not included in the 45 evaluable for response).
Partial responses (PRs) achieved across four different NRG1+ tumor types and multiple different fusion partners
Across NRG1+ tumor types, 29% overall response rate (ORR) with 13 of 45 achieving PRs, one additional unconfirmed PR was confirmed after the April 13, 2021 data cutoff date (14 of 45, 31%); median duration of exposure is 5.5 months, with 40% of evaluable patients continuing on treatment; the duration of response ranges from 1+ to approximately 12 months.
34 of 45 (76%) patients had tumor reduction
42% ORR with 5 of 12 PRs in pretreated NRG1+ pancreatic cancer
Median duration of exposure as of the April 13, 2021 data cut-off is 5.7 months, with 7 of 12 patients continuing on treatment.
In NSCLC, 25% ORR, with 6 of 24 PRs; one additional unconfirmed PR was confirmed after the data cutoff date (7 of 24, 29%).
Among all other solid tumors, 22% ORR with 2 of 9 PRs.
Zeno was observed to have a favorable and tolerable safety profile (across 157 patients treated with Zeno monotherapy as of the Jan 12, 2021 safety data cutoff date).
The majority of adverse events were mild or moderate (Grade 1 or 2) in severity.
Absence of severe gastrointestinal and skin toxicities and clinical cardiotoxicity.
Low incidence (7%) of infusion reactions
First prospective clinical validation of NRG1 fusions as actionable oncogenic drivers that may be amenable to targeted therapy with Zeno.
Merus plans the next program and clinical update for Zeno at a major medical conference by the first half of 2022.

Company Conference Call and Webcast Information

Merus will hold a conference call and webcast for investors on Sunday, June 6, 2021 at 6:00 PM ET to discuss the Zeno clinical data. A replay will be available after the completion of the call in the Investors and Media section of our website.

Date: Sunday, June 6 at 6:00 pm ET
Webcast link: available on our website
Dial-in: Toll-Free: 1-877-260-1463 / International: 1-706-643-5907
Conference ID: 9678617

About the eNRGy Clinical Trial
Merus is currently enrolling patients in the phase 1/2 eNRGy trial to assess the safety and anti-tumor activity of Zeno monotherapy in NRG1+ cancers. The eNRGy trial consists of three cohorts: NRG1+ pancreatic cancer; NRG1+ non-small cell lung cancer; and NRG1+ other solid tumors. Further details, including current trial sites, can be found at www.ClinicalTrials.gov and Merus’ trial website at www.nrg1.com or by calling 1-833-NRG-1234.

About Zeno
Zeno is an antibody-dependent cell-mediated cytotoxicity (ADCC)-enhanced Biclonics that utilizes the Merus Dock & Block mechanism to inhibit the neuregulin/HER3 tumor-signaling pathway in solid tumors with NRG1 gene fusions (NRG1+). Through its unique mechanism of binding to HER2 and potently blocking the interaction of HER3 with its ligand NRG1 or NRG1-fusion proteins, Zeno has the potential to be particularly effective against NRG1+ cancers. In preclinical studies, Zeno also potently inhibits HER2/HER3 heterodimer formation and tumor growth in models harboring NRG1 fusions.