Sutro Biopharma (STRO) Stifel 2026 Healthcare Conference 2026 summary

Platform and payload strategy

• Cell-free technology enables design across antibody, linker, payload and non-natural amino acid positioning, including ADC structures difficult to make conventionally.

• Non-natural amino acids help protect linker-payloads from cleavage in circulation; the linker is designed to release payload in tumor cells.

• Dual-payload design tunes payload ratios and positioning, including non-1:1 combinations, to balance efficacy and safety and potentially address resistance to single-payload ADCs.

• STRO-227 targets PTK7 with two payloads and DAR10; the MMAE/Topo1 combination builds on validated payload systems and aims to address resistance to single-payload ADCs.

• Broader payload work includes ATR inhibitors, PARP inhibitors and immunostimulatory agents; an Astellas collaboration combines a STING agonist with exatecan.

STRO-004 tissue factor ADC

• Phase I update in August showed antitumor activity at 3–4 mg in heavily pretreated patients, including pancreatic, lung and head-and-neck tumors; activity was seen at each dose level investigated.

• Early safety showed low cytopenia and hematologic toxicity; emerging toxicities were mainly target-related, including some stomatitis and ocular toxicity, with mitigation options available.

• PK showed higher ADC exposure with dose escalation and low free payload; circulating STRO-004 remained 98% conjugated immediately before dosing.

• Backfill cohorts are planned in tumor types showing activity; investigators are also seeking irinotecan-naive and earlier-line patients to assess activity and optimize dose, safety and durability.

• A more comprehensive efficacy and safety update at optimized doses is expected in H1 2027.

STRO-006 integrin β6 ADC

• The Phase I program entered the clinic; design features from STRO-004 carry through, with stable PK expected to help limit toxicity from linker-payload release.

• Integrin β6 is expressed across lung cancer subtypes and in head-and-neck, bladder and other tumors; the antibody was described as having strong internalization properties.

• Phase I starts at 1.5 mg/kg, above the STRO-004 starting dose, with dose escalation intended to reach the therapeutic range quickly.

• Initial clinical data are expected in H2 2027; data will be shared when sufficiently mature and meaningful.