STRO Stock Plummets 15% — What Drove The Selloff?

H.C. Wainwright believes the selloff largely reflects an overreaction to the limited efficacy details disclosed for STRO-004 by the company.

• In its early-stage trial of patients with advanced solid tumors who had already tried several prior treatments, Sutro saw tumor shrinkage in some cases of pancreatic, head and neck, and non-small cell lung cancers.
• A fuller update is planned for the first half of 2027.
• As of June 30, Sutro held $164.3 million in cash and securities, enough to fund operations into at least the second quarter of 2028.

Shares of Sutro Biopharma (STRO) fell 15% on Wednesday after the company reported second-quarter results and an early look at its lead experimental cancer drug STRO-004.

H.C. Wainwright believes the selloff largely reflects an overreaction to the limited efficacy details disclosed for STRO-004. The firm said investors had hoped for a more complete readout or enough patient-level information to judge the strength and staying power of the responses. Wainwright views the reaction as overdone because the data remain early, while the drug already shows clearer safety advantages over approved tissue-factor antibody-drug conjugates. The firm reiterated its ‘Buy’ rating and $50 price target. The price target implies a potential upside of 135% from the stock's closing price on Wednesday. 

Early Signs Of Activity With Good Tolerability

In its early-stage trial of patients with advanced solid tumors who had already tried several prior treatments, Sutro saw tumor shrinkage in some cases of pancreatic, head and neck, and non-small cell lung cancers. The drug was generally well tolerated, with dose-limiting side effects appearing only at the highest dose tested and leading to reductions rather than dropouts, the company said.

The overall rate of patients stopping treatment because of side effects was low at 6%. Enrollment of the first dose groups moved faster than expected, and the company is still refining the best dose.

A fuller update is planned for the first half of 2027. CEO Jane Chung said the early STRO-004 findings strengthen confidence in the drug’s potential to deliver meaningful benefit and open the door to combinations.

Pipeline Progress And Solid Cash Position

Beyond STRO-004, Sutro expects to start clinical testing of STRO-006, another antibody-drug conjugate for solid tumors, in the third quarter of 2026. Its wholly owned STRO-227 program remains on track for an investigational new drug application later this year and offers a longer-term growth path for the company’s platform.

As of June 30, Sutro held $164.3 million in cash and securities, enough to fund operations into at least the second quarter of 2028. Second-quarter revenue was $9.8 million, mainly from its Astellas collaboration, while the net loss was $38.5 million.

How Did Retail Traders React?

On Stocktwits, retail sentiment around STRO stock rose from ‘neutral’ to ‘bullish’ over the past 24 hours, while message volume remained at ‘high’ levels.

A Stocktwits user expressed optimism about the company’s pipeline.

STRO stock has gained 84% year-to-date. 

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