Sutro Doses STRO-006 and Narrows Operating Loss

The Tip Desk · November 13, 2026 · 3 min read

The clinical-stage ADC company posted a $22.0 million operating loss in the third quarter as STRO-006 entered the clinic and cash fell to $142.2 million.

Sutro Biopharma (STRO), a clinical-stage oncology company developing antibody-drug conjugates, reported a narrower operating loss in the third quarter as it put a second wholly owned ADC into the clinic and booked a milestone from Astellas.

Loss from operations was $22.0 million in the three months ended September 30, 2026, compared with $48.5 million a year earlier. Net loss was $31.5 million, or $1.90 a share, versus $56.9 million, or $6.66 a share, a year earlier. Weighted-average shares used in computing basic and diluted loss per share were 16.6 million, versus 8.5 million.

Revenue was $9.1 million, compared with $9.7 million for the year-ago quarter, with the 2026 amount related principally to the Astellas collaboration.

Total research and development and general and administrative expenses were $31.0 million, compared with $48.6 million a year earlier. Research and development expense was $23.5 million, versus $39.9 million; general and administrative expense was $7.5 million, versus $8.7 million. Restructuring and related costs were $16 thousand, versus $9.6 million a year earlier.

In October 2026, Sutro announced the first patient dosed in a Phase 1 study of STRO-006, its integrin β6-targeting ADC with a DAR8 exatecan payload, after saying in the prior quarter that the program was on track to enter the clinic in the third quarter of 2026. Dose escalation will enroll patients with ITGB6-expressing tumors, including head and neck, non-small cell lung, esophageal/gastric, colorectal, endometrial, urothelial and breast cancers, beginning at 1.5 mg/kg. The company anticipates an initial Phase 1 data update in the second half of 2027.

STRO-004, the Tissue Factor-targeting DAR8 exatecan ADC in the Phase 1 STRIVE-01 study, remains in dose optimization. Initial dose escalation in 49 heavily pretreated patients had shown confirmed and ongoing unconfirmed partial responses across three tumor types, with favorable tolerability. The company plans to provide its next STRIVE-01 update and initiate expansion cohorts in select indications in the first half of 2027.

STRO-227, a PTK7-targeting dual-payload ADC combining MMAE and exatecan, is advancing toward initiation of a Phase 1 trial in early 2027, after the prior quarter had described it as advancing toward IND submission later in 2026.

Under the Astellas collaboration, a second dual-payload immunostimulatory ADC targeting B7-H3 began dosing patients, resulting in a $10 million milestone payment received by Sutro in October 2026. The first partnered program, targeting TROP2, continues to dose patients.

Cash, cash equivalents and marketable securities were $142.2 million as of September 30, 2026, down from $164.3 million as of June 30, 2026. Based on its current operating plan, the company expects that cash to support operations into the first half of 2028, versus the prior expectation of at least the second quarter of 2028.

Chief Executive Officer Jane Chung said two programs, STRO-004 and STRO-006, entered the clinic in less than a year, with STRO-227 expected to follow in early 2027.