Don't Buy Summit Therapeutics Until This Big Thing Happen

Sometimes, everything can seem to be going your way. And then the wheels fall off. That's the situation Summit Therapeutics (NASDAQ: SMMT) finds itself in.

Shares of the clinical-stage biotech company skyrocketed 584% last year. The stock more than doubled again by late April 2025. However, Summit subsequently gave up all of its year-to-date gains and then some.

What happened? Summit's lead pipeline candidate, ivonescimab, failed to achieve a statistically significant overall survival benefit in a phase 3 clinical study targeting non-small cell lung cancer (NSCLC) conducted by the company's partner, Akeso (OTC: AKES.F).

Some investors may be tempted to load up on this beaten-down biotech stock after its steep sell-off. However, don't buy Summit Therapeutics until one big thing happens.

Rolling the dice

Summit has planned for months to submit a Biologics License Application (BLA) to the U.S. Food and Drug Administration (FDA) for ivonescimab in combination with chemotherapy as a second-line treatment for NSCLC. The company's intention was and is to use the results from the Harmoni clinical study to support this BLA.

But there's a glaring issue with this plan. The FDA told Summit that ivonescimab plus chemo needed a statistically significant overall survival benefit to win marketing approval. This requirement wasn't met in the Harmoni study.

Summit was left with a huge decision on how to proceed. On Oct. 20, 2025, the drugmaker revealed its strategy: Roll the dice anyway. Summit intends to move forward with the BLA based on the Harmoni data despite the FDA's guidance.

What is Summit's management thinking? They seem to believe that they will be able to convince the FDA to change its mind based on the remaining safety and efficacy data from the Harmoni study.

Acceptance is critical

In case you haven't guessed it already, the big thing to wait on before buying any shares of Summit Therapeutics is the FDA's decision on whether to accept or reject the BLA for ivonescimab plus chemo. Acceptance is critical for the company.

Summit hasn't announced the filing of the BLA yet. However, it plans to do so in the fourth quarter of 2025. That leaves only a few weeks to move full steam ahead. The FDA has 60 days to accept or reject a BLA after its submission.

Image source: Getty Images.

Interestingly, the company's management didn't provide any indications during the third-quarter earnings call in October that the FDA had hinted about the possibility of changing its mind on the overall survival requirement. Urte Gayko, Summit's Chief Regulatory, Quality, and Pharmacovigilance Officer, stated, "We have continued interaction with the FDA." She added that the company is "looking forward to getting specific feedback and giving some color earlier next year after the submission."

A binary outcome

If Summit's gamble pays off and the FDA accepts the BLA, expect the stock to soar. If the drugmaker's roll of the dice fails, its shares will almost certainly decline further. The FDA's decision is a textbook example of a binary outcome. However, investors need to understand that the acceptance or rejection of Summit's BLA won't be the end of the story, regardless of the decision.

Let's assume that the FDA accepts the BLA. Although it would be a key win for Summit, it would not necessarily mean that the agency will ultimately decide to approve ivonescimab in combination with chemotherapy as a second-line treatment for NSCLC. Investors would still have to wait for the FDA's final decision.

On the other hand, an FDA rejection of the BLA wouldn't translate to a death knell for Summit. The company expects to report data from its Harmoni-3 phase 3 study of ivonescimab combined with chemo as a first-line treatment for squamous NSCLC in the second half of 2026. Summit may be able to use this data to file another BLA.

Whatever ultimately happens, the looming decision by the FDA about whether or not to accept the first BLA for ivonescimab plus chemo will be a catalyst for Summit's stock one way or the other. Investors will probably be better off staying on the sidelines in the meantime.

Keith Speights has no position in any of the stocks mentioned. The Motley Fool has positions in and recommends Summit Therapeutics. The Motley Fool has a disclosure policy.