Tango Therapeutics Stock Tumbles 16% Despite 82% Response Rate in Pancreatic Cancer Combo Trial at ESMO

NEW YORK — Tango Therapeutics shares fell more than 16% in early trading Friday. The biotech company presented updated results for its pancreatic cancer drug combination at a major medical meeting, but investors sold the stock after a strong run-up ahead of the data.

The stock fell $4.53 to $23.40, with more than 3.8 million shares traded, above its three-month daily average. Shares had risen about 28% in the days before the release, from about $21.89 on Oct. 13 to Thursday's close of $27.93. They are still up more than 270% over the past year.

Boston-based Tango presented the data at the European Society for Medical Oncology Congress in Madrid. The trial tested its experimental drug vopimetostat together with daraxonrasib, an experimental drug from Revolution Medicines.

The data

The study enrolled previously treated patients with metastatic pancreatic cancer whose tumors carry two specific genetic changes, an MTAP deletion and a RAS mutation.

Of 22 patients who could be evaluated for effectiveness, 18 saw their tumors shrink, a response rate of 82%. Every patient had their disease controlled. Nine months into treatment, 88% had not seen their cancer progress. Median progression-free survival has not yet been reached. Thirteen of the 22 patients received the combination as their third line of treatment.

The data were collected through Aug. 20.

"Achieving this level of durability with an oral, chemotherapy-free regimen is particularly meaningful for patients," said Dr. Alexander Spira, the study's principal investigator.

Dr. Anna Berkenblit of the Pancreatic Cancer Action Network said "these results warrant rapid evaluation in a larger, randomized Phase 3 trial."

Compared with June

The new figures are based on more patients and longer follow-up than the first look Tango released in June. At that time, 11 of 12 evaluable patients, or 92%, had responded, and 90% were free of progression at six months.

The response rate in the larger group was lower than the earlier figure, as is common when early trials add patients. Analysts did not publicly tie Friday's decline to the change.

Safety

At the lower dose, the combination was generally well tolerated in 25 pancreatic cancer patients. There were no dose-limiting toxicities and no patients stopped treatment because of side effects. Forty percent had serious, or Grade 3, side effects, and 20% needed a dose reduction. The most common side effects were mouth sores, rash and diarrhea.

A higher dose tested in four patients was not well tolerated. Two patients had a total of three dose-limiting toxicities.

A separate arm combining vopimetostat with zoldonrasib, another Revolution Medicines drug, in patients with a specific KRAS mutation showed a 54% response rate among 35 evaluable patients.

Phase 3 plans

After discussions with the Food and Drug Administration, Tango plans to start a global Phase 3 trial in the first half of 2027. It will test the combination against standard chemotherapy as a first treatment in patients with MTAP-deleted pancreatic cancer.

"We are focused on initiating a planned registrational Phase 3 trial of vopimetostat with daraxonrasib," CEO Dr. Malte Peters said.

The company also plans to talk with regulators about seeking approval in previously treated patients and to explore combinations in other tumor types.

"We view PRMT5 inhibition as an emerging backbone in combination treatment strategies in PDAC and beyond," Peters said, referring to pancreatic ductal adenocarcinoma, the most common form of pancreatic cancer.

Why the selloff

Some investors appeared to take profits after the stock's rise into the meeting, a common pattern for biotech companies after major data releases. The Phase 3 trial is more than a year away, and approval would come years later.

The broader market was also weak. The Nasdaq had its worst session since June on Thursday amid concerns about AI spending.

A company affiliate also filed a notice to sell up to 15,231 shares, according to a regulatory filing. Such sales are often planned in advance.

Pancreatic cancer is one of the deadliest cancers, with few effective treatments for advanced disease. Drugs targeting RAS mutations, which drive most pancreatic tumors, are among the most closely watched areas in cancer research. That interest has driven big gains in both Tango and Revolution Medicines this year.