Merus: Taking the Long View in Cancer Innovation

Most antibody cancer drugs are designed to zero in on a single target on a tumor cell. That strategy has delivered important therapies but comes with trade-offs. Many of these markers are not exclusive to cancer, appearing in smaller amounts on healthy tissue and raising the risk of side effects. Tumors, meanwhile, can adapt, sometimes evading treatment by altering or shedding the targeted protein.

Merus built its strategy around a simple yet consequential idea: Cancer is rarely defined by one signal. The company engineers bispecific and trispecific antibodies that bind to two or three substances. Instead of acting on a single cue, these antibodies are designed to fully engage only when multiple signals appear together on the same cell, a pattern far more typical of cancer cells than healthy ones.

That makes it harder for tumors to escape. Merus pairs this with an approach that closely resembles natural human antibodies, supporting stability and predictable behavior in the body. Importantly, it also reduces development and commercial risks, as regulators and physicians are already familiar with this format.

Platform to proof

EQT Life Sciences first invested in the Dutch company in 2010, when its antibody platform was scientifically differentiated, but still in its early stages. EQT, then LSP, led the first large financing, supported the company through successive funding rounds and provided strategic guidance, with active board involvement for roughly a decade. The company’s Nasdaq IPO in 2016 was a key milestone, providing access to deeper capital markets to fund its expansion.

The concept is elegant on paper, but the real test is clinical proof. In 2024, Merus received FDA-accelerated approval for a bispecific antibody for patients with advanced cancers driven by rare mutations known as NRG1 fusions and the first therapy specifically targeting this alteration. An important milestone that offered tangible evidence that the platform could translate into approved medicines.

Meanwhile, its broader pipeline is maturing. Lead programs in head and neck, as well as colorectal, cancer are in late-stage development, with data pointing to potential use in earlier lines of therapy. This is a notable step in oncology, where the bar for earlier-line adoption is typically high – although these candidates remain in clinical development and subject to regulatory approval.

Patience, then payoff

The Merus story is as much about endurance as it is about engineering. Antibody platform companies are capital-intensive and complex by design, requiring repeated financing and long clinical timelines. Merus, co-founded by Ton Logtenberg in 2003, continued to invest in its platform while advancing multiple assets into late-stage trials and actively protecting the intellectual property covering its platform technology.

That long horizon, combined with the company’s platform, late-stage assets and FDA-approved product, translated into concrete interest from the pharma industry. The 2025 acquisition by Genmab, valued at $8bn, reflected more than enthusiasm for a single drug. It signaled pharma’s growing appetite for multi-specific antibodies as a next wave in targeted cancer therapy, where hitting multiple targets with one molecule may lead to better outcomes for patients. The deal marked one of Europe’s largest biotech acquisitions to date.

“As part of Genmab, the company is now one step closer to delivering better treatments and transforming the lives of patients,” says René Kuijten, partner and head of EQT Life Sciences.

Merus’s trajectory is also part of a wider shift: Large drugmakers are increasingly willing to pay for platforms that are not only innovative but validated. Multi-specific antibodies have progressed from concept to accepted therapy, and Merus is among the companies that have proven they can produce real medicines.