ASCO: Merus' gene-targeting cancer drug shrinks tumors. Will execs go it alone or partner?

Merus’ NRG1 gene targeting cancer treatment helped to shrink tumors and kept working for up to 9.1 months, leaving the company’s leadership with an important question: partner up or go it alone for commercialization?

A regulatory filing is still far off, but with a cancer med that could enter a completely new market for patients with a rare and aggressive gene abnormality, who have previously not had a treatment option, the company is prepping its commercial strategy now.

Presenting at the American Society of Clinical Oncology annual conference, Merus rolled out interim data from the phase 1/2 eNRGy trial and early access program for zenocutuzumab, or zeno, which featured patients who have NRG1 fusion-positive cancer. Trial patients had a variety of tumor types but mostly non-small cell lung cancer and pancreatic ductal adenocarcinoma. The study's primary endpoint is overall response and secondary endpoints include duration of response.

The analysis included 83 patients out of 110, with efficacy determined in 79 who were eligible for an assessment as of the April 12 cutoff date. Merus found that zeno led to tumor shrinkage in 70% of patients and clocked a median response duration of 9.1 months. Twenty out of the 83 total patients were continuing on treatment as of the cutoff date. The median time to response was 1.8 months and median duration of exposure was 6.3 months.

Looking at the total population, overall response was 34% for all tumor types assessed. The response was strongest in the pancreatic cancer patients at 42%, compared with 35% of the lung cancer patients. The efficacy was consistent across these two main tumor types examined in the trial, Merus Chief Medical Officer Andrew Joe, M.D., said in an investor presentation Sunday.

As for safety, Merus said zeno had a low incidence of grade 3 or higher treatment-related adverse events including a low rate of severe gastrointestinal and dermatologic toxicity and no “clinically significant cardiotoxicity.”

Zeno, a bispecific antibody, was originally planned to tackle solid tumors and Merus found in early clinical evidence that it might have more promise in cancers that have the rare but aggressive abnormality of the NRG1 gene.

The latest release at ASCO does prompt the partnering possibility, either now or later. 

If Merus is able to gather enough evidence to support an approval, it could find a market without a current standard of care. The company is therefore already actively working on its commercial strategy, according to CEO Bill Lundberg, M.D.

Chief Commercial Officer Shannon Campbell detailed that plan on the investor call, noting that investigators and doctors have said the efficacy of zeno is clinically meaningful and the once every two weeks dosing schedule is convenient for patients.

The number one challenge for Merus is establishing the infrastructure to support zeno and the genetic testing required to identify patients. The company is therefore considering partnership scenarios for the med but has also prepared digital “go-it-alone” strategies as well.

Merus has already received FDA feedback suggesting that data from the eNRGy trial could support a biologics license application for NRG1 fusion cancer, Lundberg said. The company may have enough patients enrolled and sufficient follow-up data by the middle of this year, which could be used to build the application.

Lundberg said to expect an update on the regulatory and commercial efforts in the second half of this year. Merus is also considering exploring earlier lines of treatment for NRG1 cancers, he added.

Zeno has already been granted an orphan drug designation in pancreatic cancer and a fast-track designation for NRG1 fusion cancer.