Sutro Biopharma (STRO) Investor presentation summary

Platform and pipeline

• Cell-free ADC platform combines engineered antibodies, Fc-silent design, site-selective non-natural amino acid conjugation, stable β-glu linkers and high-DAR or dual-payload formats.

• Platform design aims to improve tumor selectivity, systemic stability, exposure and therapeutic index while limiting free payload and toxicity.

• Pipeline includes STRO-004 (TF), STRO-006 (ITGβ6) and STRO-227 (PTK7 dual-payload), alongside partnered TROP2- and B7-H3-targeting immunostimulatory ADCs.

STRO-004

• Phase 1 dose escalation ongoing at 1–5 mg/kg; confirmed and ongoing unconfirmed partial responses reported at 3–4 mg/kg in PDAC, HNSCC and NSCLC.

• Early activity observed in heavily pretreated patients across 8 tumor types unselected for TF expression; median 3 prior lines of therapy, range 1–7.

• Across 49 patients, tolerability was described as favorable, with mostly Grade 1–2 adverse events, 6% discontinuation due to adverse events and no discontinuations due to dose-limiting toxicities.

• Exposure was dose-proportional, half-life nearly 7 days, DAR8 configuration maintained at 98%, and free exatecan remained below 10 ng/mL across doses.

• Next study update and initiation of selected-indication expansion cohorts planned for 1H 2027.

STRO-006

• ITGβ6-targeting DAR8 exatecan ADC; Phase 1 initiated in 3Q 2026, with initial clinical data expected in 2H 2027.

• Preclinical PDX activity at a single 5 mg/kg dose included responses in 43/58 models (74%): HNSCC 15/21, adenocarcinoma NSCLC 14/19 and squamous NSCLC 14/18.

• In NSCLC PDX models, STRO-006 ORR was 28/37, versus 17/37 for Dato-DXd and 10/35 for SGN-B6A.

• Phase 1 dose escalation starts at 1.5 mg/kg; the stated NHP highest non-severely toxic dose is 30 mg/kg.