Merck acquisition brings Terns CML treatment into pipeline
Oral treatment TERN-701, currently in trials, has FDA orphan drug designation
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Merck is set to acquire Terns Pharmaceuticals in a $6.7 billion deal aimed at expanding its oncology pipeline, including an experimental treatment for chronic myeloid leukemia (CML).
The acquisition will give Merck access to Terns’ lead candidate, TERN-701, an oral therapy under development for certain people with CML, a type of blood cancer characterized by the overproduction of abnormal white blood cells.
The companies expect to close the acquisition in the second quarter of 2026, pending regulatory approval and other customary conditions.
“The acquisition of Terns builds on our growing presence in hematology with TERN-701, a potential best-in-class candidate for the treatment of certain patients with chronic myeloid leukemia,” Robert M. Davis, chairman and CEO of Merck, said in a company press release. “This transaction further diversifies and strengthens our position in oncology as we continue to look for opportunities to broaden our portfolio into other therapeutic areas.”
Under the terms of the agreement, Merck will acquire all shares of Terns, bringing the company and its drug development programs fully under Merck’s control.
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“This acquisition reflects our team’s deep commitment to innovation in oncology and developing high impact medicines,” said Amy Burroughs, Terns’ CEO. “By working together, we will advance TERN-701, leveraging the deep expertise and significant resources at Merck, a global biopharmaceutical leader with a proven track record of delivering cancer breakthroughs for patients who need them most.”
CML is often associated with a genetic mutation known as the Philadelphia chromosome, which creates an abnormal fusion gene called BCR-ABL1. This gene produces an abnormal enzyme, a tyrosine kinase, that signals cells to grow uncontrollably, driving the disease.
TERN-701 belongs to a class of drugs known as tyrosine kinase inhibitors (TKIs), which are designed to block the BCR-ABL1 enzyme and help to slow or stop the growth of leukemia cells.
CML typically progresses through three phases — chronic, accelerated, and blast — with most patients diagnosed in the chronic phase, the earliest stage of the disease. With appropriate treatment, many patients can avoid progression to more advanced stages. However, current therapies can be limited by resistance or side effects, highlighting the need for new treatment options.
Unlike most current TKIs, which bind to the active site of an enzyme, TERN-701 is designed to bind to a different region, known as an allosteric site. This approach may allow the therapy to remain effective even when mutations in the enzyme make it resistant to standard treatments.
TERN-701 is being evaluated in the Phase 1/2 CARDINAL trial (NCT06163430), which is expected to enroll up to 180 adults, aged 18 and older, with chronic-phase, Philadelphia chromosome-positive CML who have received at least one TKI but did not respond adequately or could not tolerate treatment.
The Phase 1 part of the study is testing the safety of increasing doses of TERN-701, taken once daily in continuous 28-day cycles, to help identify the optimal dose for the Phase 2 part. In the Phase 2 portion, the safety and efficacy of two selected dose levels will be assessed in a larger patient population. The therapy is also being evaluated at 500 mg doses in an additional group of patients with specific genetic mutations linked to resistance to existing therapies.
The trial is currently recruiting at several sites across the U.S., Europe, South Korea, Australia, and New Zealand.
Early clinical data show promising activity, including encouraging rates of major molecular response — meaning very low levels of BCR-ABL1 in the blood or bone marrow — and deep molecular response, where BCR-ABL1 levels become extremely low or even undetectable by week 24. Responses have been observed even in patients who had received multiple prior treatments, including those treated with an allosteric TKI, according to the company.
The treatment has also shown a favorable safety profile, with most side effects reported as mild and low rates of severe side effects and treatment discontinuation.
“The first approval of a BCR::ABL1 tyrosine kinase inhibitor 25 years ago transformed the prognosis for many patients with chronic myeloid leukemia,” said Dean Y. Li, MD, PhD, president of Merck Research Laboratories. “Despite new therapeutic options, there is significant need for innovative, well-tolerated therapies with faster time to onset of molecular response leading to deeper responses and better disease control.”
Early clinical evidence shows the treatment “may have the potential to provide a meaningfully differentiated option for certain patients living with CML,” Li said.
The U.S. Food and Drug Administration (FDA) in 2024 granted the therapy orphan drug designation, a status intended to support the development of treatments for rare diseases, defined as those affecting fewer than 200,000 people in the U.S.
