Sutro Biopharma receives Nasdaq notice for falling below $1.00 bid price

The notice

Sutro Biopharma, Inc. (Nasdaq: STRO) said in a Form 8-K dated June 20, 2025 and filed June 25, 2025 that it received written notice on June 20 from The Nasdaq Stock Market LLC. The notice says the company is not in compliance with the $1.00 minimum bid price requirement for continued listing on the Nasdaq Global Market, under Listing Rule 5450(a)(1).

The 8-K does not state the company's closing bid price on or around June 20, and it gives no share count or market value figure. It is signed by David Pauling, chief administrative officer and general counsel.

The deadlines and the options

Under Listing Rule 5810(c)(3)(A), Sutro has 180 calendar days, or until December 17, 2025, to regain compliance. To do so, its closing bid price must be at or above $1.00 a share for at least ten consecutive business days within that period.

If the company is not compliant by December 17, 2025, it may get a second 180-day period, but only if it transfers to the Nasdaq Capital Market. To qualify for that transfer, it would need to meet the Capital Market's market value of publicly held shares requirement and its other initial listing standards, apart from the bid price rule. It would also have to notify Nasdaq of its intent to cure the deficiency, which may include a reverse stock split.

If the company does not regain compliance in the allowed periods, Nasdaq will issue a delisting notice. Sutro could then appeal to a Nasdaq Listing Qualifications Panel and request a hearing. The company says it will monitor its closing bid price and, if necessary, plans to implement a reverse stock split before December 17, 2025.

The pipeline behind the listing

The 10-K, filed March 13, 2025, describes Sutro as an oncology company developing site-specific antibody drug conjugates (ADCs) on its XpressCF and XpressCF+ cell-free protein synthesis platforms. Its highest-priority wholly owned candidate is STRO-004, a preclinical ADC directed against tissue factor for solid tumors. The company anticipated submitting an IND for STRO-004 in the second half of 2025. The 10-K calls its preclinical data potent, with potential for a differentiated safety profile, and it does not present clinical results for the program.

The company's most advanced former asset, luvelta (STRO-002), was in development from 2018 to February 2025. After a strategic review in March 2025, Sutro chose to deprioritize further investment in it, though it says it will look for partners to make the drug available. Luvelta is licensed to Tasly for Greater China under an agreement from December 2021, amended in April 2022.

The partners

The 10-K says Sutro has received about $980 million in payments from its collaborations through December 31, 2024, including about $79 million in investments in its stock. Its partners include Ipsen, which received an exclusive license to STRO-003 in 2024; Astellas, under a 2022 license for immunostimulatory ADCs; Merck; Bristol Myers Squibb's Celgene unit; and EMD Serono.

The 10-K also records setbacks in those alliances. Astellas notified the company in 2024 that it would not nominate a third target program, and preclinical work on the first two targets continues. The collaborations with Merck, BMS and EMD Serono each produced a development candidate that entered clinical development. But the 10-K says each partner, as part of its own strategic portfolio review, elected to end further clinical development of the candidate molecules after Phase 1 studies.

What comes next

The next dated item is the December 17, 2025 compliance deadline. Whether the company moves to the Nasdaq Capital Market, or plans a reverse split, the 8-K describes both options only as possibilities.

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