GSK (GSK) ESMO 2026 Investor Briefing summary

Small-cell lung cancer

• In China-only phase III ARTEMIS-008, risvutatug rezetecan (Ris-Rez) improved median OS to 18.5 vs 10.3 months with topotecan (HR 0.46; P<0.0001); BICR median PFS was 7.2 vs 3.0 months (HR 0.33).

• ARTEMIS-008 ORR was 58.3% vs 12.8% with topotecan; DCR was 90.4% vs 60.2%.

• Global phase I-II second-line+ SCLC cohort showed 61% ORR at 8 mg/kg in 18 patients, consistent with the 58% ORR in ARTEMIS-008.

• Across 558 patients in the global program, all-grade ILD incidence was 4% and Grade ≥3 incidence was <1%; in the ARTEMIS-008 Ris-Rez arm, Grade 3+ incidence was 4%.

• EMBOLD-SCLC-301 is recruiting; a first-line phase III study was expected to start before year-end, with combinations under evaluation and some tarlatamab-exposed patients included.

Relapsed or refractory osteosarcoma

• In phase III ARTEMIS-011, Ris-Rez improved BICR median PFS to 5.5 vs 1.4 months with gemcitabine-docetaxel (HR 0.33; P<0.0001); median follow-up was 7.1 months.

• BICR ORR was 15% vs 2%, and DCR was 76% vs 33%.

• OS was immature and not reached in either arm; HR was 0.51 despite 17 control-arm patients crossing over.

• At 12 mg/kg, myelosuppression, including neutropenia and thrombocytopenia, predominated; treatment discontinuations were 4%.

Platinum-resistant ovarian cancer

• In BEHOLD-1, confirmed ORR increased with Mo-Rez dose: 36% at 2.8 mg/kg, 57% at 4.8 mg/kg and 62% at 5.8 mg/kg, the advancing dose.

• At 5.8 mg/kg Q3W, median duration of response was 12.2 months and median PFS was 11.1 months; 6-month PFS probability was 80%.

• Responses occurred across B7-H4 expression levels; 2 of 4 patients previously treated with mirvetuximab had partial responses.

• ILD/pneumonitis occurred in 9 patients (7%) across dose levels; 8 events were Grade 1–2. At 5.8 mg/kg, ILD incidence was 2%; G-CSF prophylaxis is strongly recommended from treatment start across the BEHOLD program.

• Five global phase III studies span platinum-resistant and platinum-sensitive ovarian cancer, first-line HR-proficient ovarian maintenance, and second-line and first-line MMR-proficient endometrial cancer.