Merck Just Bet $6.7 Billion on a Drug Most People Haven't Heard Of

CML patients already have treatment options called tyrosine kinase inhibitors, or TKIs. Think of TKIs as keys that block a specific lock (a protein called BCR-ABL) driving the cancer. The problem is that existing keys don't always work. Some patients develop resistance mutations, essentially changing the lock so the old keys no longer fit.

TERN-701 is designed as a next-generation key. It works differently from current options, binding to a separate spot on the protein (an "allosteric" site, for the science nerds). This potentially lets it work even when mutations have foiled other drugs.

The early results look genuinely impressive. In the ongoing CARDINAL Phase 1/2 trial, 75% of patients achieved a major molecular response (a deep reduction in cancer signals) by 24 weeks. About 36% achieved an even deeper response. And the safety profile was clean: serious side effects like low blood cell counts showed up in only about 8% of patients.

The FDA granted TERN-701 Fast Track designation in late 2025, a signal that regulators see it addressing an unmet medical need. Pivotal dose selection and an FDA end-of-Phase 2 meeting are both expected around mid-2026.

The Price Tag: Bargain or Overpay?

Let's talk about the money, because the valuation math on this deal is fascinating.

Terns' stock had been on a tear. By early March 2026, the stock had climbed above $42. The run-up was driven by strong clinical data and, almost certainly, takeover speculation.

Merck's $53 offer represents just a 6% premium to Terns' March 24 closing price. That's paper-thin by biotech acquisition standards, where premiums of 30-50% are common. But zoom out a bit and the picture changes. Compared to Terns' 60-day volume-weighted average price, the premium was 31%. Against the 90-day average, it was 42%.

In other words, Merck is paying a hefty premium to where Terns was trading a few months ago, but barely a nudge above where the stock sat the day before the announcement. The market had, in many ways, already priced in a deal. Terns' stock had risen roughly sixfold in the months leading up to this, fueled by clinical hype and buyout whispers.

Merck will take a $5.8 billion charge (about $2.35 per share) against its 2026 results. That's the accounting hit when you buy a company whose primary asset hasn't been approved yet: you're essentially purchasing an expensive lottery ticket and writing it down immediately.

A Phase 1/2 Asset for $6.7 Billion: Is Merck Overpaying?

This is where opinions diverge. Paying nearly $7 billion for a drug that hasn't even started pivotal trials is, by any historical standard, aggressive. The first pivotal study isn't expected to launch until late 2026 or early 2027, and it'll test TERN-701 against existing second-generation TKIs in patients who've already failed initial treatment.

But consider the competitive context. Novartis already has Scemblix (asciminib) on the market, a similar allosteric BCR-ABL inhibitor that's been gaining traction. Merck's R&D head, Dr. Dean Li, specifically noted TERN-701's potential advantages over existing TKIs, including Scemblix. If TERN-701 can show superiority or match Scemblix's results while expanding into resistant patient populations, the addressable market could be substantial.

The CML market isn't enormous by Keytruda standards; nothing is. But it's durable. CML patients take their medication for years, sometimes decades. That recurring revenue stream is exactly what Merck needs as it stares down a future of biosimilar erosion.

Merck's Bigger Chess Game

This deal doesn't exist in isolation. Merck has been making moves across the board to prepare for life after Keytruda.

On the defensive side, the company won FDA approval for Keytruda Qlex, a subcutaneous injection, in September 2025. It covers approximately 13 tumor types and can be administered faster than the traditional IV infusion. Pricing it at parity (around $12,031 per three-week cycle) is a play to retain patients through convenience, even as biosimilars eventually undercut on price. It's like a coffee shop adding a drive-through right before a competitor opens next door.

On the offensive side, Merck's collaboration with Moderna on a personalized mRNA cancer vaccine (mRNA-4157/V940) is moving through Phase 3 trials. In Phase 2b, the vaccine combined with Keytruda cut melanoma relapse risk in half. It has Breakthrough Therapy designation, and a filing could come as early as late 2025 or 2026.

There's also the Keytruda plus Welireg combination for kidney cancer, which became the first combo to beat PD-1 monotherapy in the adjuvant setting. A supplemental filing is expected in 2025 or 2026.

The Terns acquisition fits into a broader pattern: buy external assets, defend Keytruda's franchise through reformulation, and build new combinations around it. It's a three-pronged strategy born out of necessity.

What Happens Next

The deal is structured as a tender offer, meaning Merck doesn't need a traditional shareholder vote. A Merck subsidiary will bid for a majority of Terns' shares, followed by a merger to scoop up the rest. The only major hurdle is antitrust clearance under the Hart-Scott-Rodino Act, which shouldn't be controversial given the companies don't overlap in the CML market.

Closing is expected in Q2 2026, which lines up nicely with Terns' upcoming milestones: pivotal dose selection, the FDA end-of-Phase 2 meeting, and updated data from the CARDINAL trial, all expected in the second half of this year.

Merck plans to absorb Terns' pipeline and advance TERN-701 toward registration trials. Terns' metabolic programs (a THR-β agonist, a GIPR antagonist, a GLP-1 receptor agonist) are available for partnering but won't be Merck's focus. This acquisition is about one thing: cancer.

The Bottom Line

Merck is paying a king's ransom for a drug that's still early in its clinical story. That's a bet on the science, yes, but it's also a bet on timing. With Keytruda's patent cliff now less than three years away and billions of dollars in annual revenue at stake, Merck doesn't have the luxury of waiting for Phase 3 data before making a move.

Terns' TERN-701 gives Merck a foothold in hematologic oncology, a differentiated mechanism of action, and a pipeline asset with genuine best-in-class potential. Whether it was worth $6.7 billion, we'll know in a few years. But in pharma's game of musical chairs, sometimes the cost of sitting out is higher than the cost of overpaying.

Merck would rather be early and expensive than late and empty-handed.

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