GSK has announced the first global data for risvutatug rezetecan (Ris-Rez), its investigational B7-H3-targeted Antibody Drug Conjugate (ADC), in patients with relapsed Extensive-Stage Small Cell Lung Cancer (ES-SCLC). Results from the phase 1b dose-optimisation portion of the EMBOLD PanTumor-101 trial showed positive anti-tumor activity and a manageable safety profile, adding to recently reported positive phase 3 data in patients with SCLC in China.

In the trial, Ris-Rez achieved a confirmed Objective Response Rate (ORR) of 61 percent among evaluable patients at the 8 mg/kg dose (n=11/18; 95 percent CI: 35.7-82.7), compared with 32 percent at the 6 mg/kg dose (n=7/22; 95 percent CI: 13.9-54.9). These findings will be presented in a poster session at the European Society for Medical Oncology (ESMO) Congress 2026 in Madrid, Spain. Along with data from Hansoh’s phase 3 ARTEMIS-008 study in SCLC, this data supported selection of the 8 mg/kg dose currently being evaluated in GSK’s global phase 3 EMBOLD SCLC-301 study.

Hesham Abdullah, Senior Vice President, Global Head of Oncology, R&D, GSK, said, “Today’s first global data for Ris-Rez build on the statistically significant Overall Survival benefit recently reported in Hansoh’s pivotal Chinese trial. As the data for Ris-Rez continues to grow, we remain focused on accelerating development in Extensive-Stage Small Cell Lung Cancer, where patients often relapse quickly and urgently need more treatment options.”

The safety profile was manageable across both dose levels at a median follow-up of 100.5 days. Grade 3 or higher Treatment-Related Adverse Events (TRAEs) were observed in 42 percent of patients receiving 8 mg/kg and 15 percent of those receiving 6 mg/kg, with haematological events being the most common. The overall rate of Interstitial Lung Disease (ILD) was low (2 percent; 1 out of 50 patients) and the case was moderate (grade 2).

Hye Ryun Kim, MD, PhD, Division of Medical Oncology, Yonsei Cancer Center, and a study investigator in the EMBOLD PanTumor-101 study, said, “Extensive-Stage Small Cell Lung Cancer remains one of the most aggressive cancers we treat, with 5-year survival rates typically in the single digits. Patients whose disease relapses often have limited options, and current therapies can be difficult to tolerate. The response rates and manageable safety profile observed with Ris-Rez are encouraging and support its ongoing development in this setting.”

These data will be presented alongside a broader set of findings from the EMBOLD program at ESMO 2026, including global dose-escalation results from EMBOLD PanTumor-101, an analysis of ILD across the Ris-Rez early clinical program, and the design of the global phase 3 EMBOLD SCLC-301 study. Real-world evidence from the RESONANCE study further demonstrates the complexity of treatment decision-making after relapse in ES-SCLC and highlights the absence of a clear treatment standard in later lines of therapy. Together, these findings contribute to the growing body of evidence for Ris-Rez and reflect GSK’s focus on advancing targeted medicines where significant patient need and scientific opportunity remain.

EMBOLD PanTumor-101 (NCT06551142) is a global, open-label phase 1a/b study evaluating the safety, tolerability and clinical activity of Ris-Rez monotherapy in adult patients with advanced or metastatic solid tumours. In the phase Ib dose-optimisation portion of the study, patients with relapsed (2L+) ES-SCLC were randomised to receive Ris-Rez 6 mg/kg or 8 mg/kg intravenously every 3 weeks until disease progression, unacceptable toxicity, loss to follow-up or death.

The analysis presented at ESMO 2026 included 50 patients who had received a median of 2 prior therapies. The study population included patients with prior topoisomerase-1 inhibitor or tarlatamab exposure, as well as patients with brain or liver metastases. Enrolment in the phase 1b dose-optimisation portion of the trial was still ongoing at data cut-off, and longer follow-up will be needed to further characterise the Durability of Response (DoR).

Ris-Rez is a novel investigational ADC targeting the B7-H3 protein, which is highly expressed over 10 solid tumor types, supporting GSK’s ambition to develop it across more than 40 indications by 2040.

GSK acquired exclusive worldwide rights (excluding China’s mainland, Hong Kong, Macau, and Taiwan) from Hansoh Pharma to progress clinical development and commercialisation of Ris-Rez.

More than 1,000 patients have received Ris-Rez as part of GSK’s global EMBOLD clinical trial program, which includes phase 3 trials in late-line ES-SCLC and metastatic Castration-Resistant Prostate Cancer (mCRPC), with additional upcoming phase 3 trials planned in early-line SCLC and chemo-naïve mCRPC.

Ris-Rez has received several global regulatory designations to date, including Orphan Drug Designations (ODDs) in the US, Japan and the EU for SCLC, and Breakthrough Therapy Designation (BTD) in the US and Priority Medicines (PRIME) Designation from the European Medicines Agency (EMA) for relapsed or refractory ES-SCLC, among others.

SCLC is associated with rapid progression and accounts for approximately 10-15 percent of all lung cancer diagnoses worldwide. It is characterised by early metastatic spread, frequent relapse and poor prognosis. Approximately, 70 percent of patients with SCLC are diagnosed with extensive-stage disease (ES-SCLC), meaning the cancer has spread throughout one or both lungs and/or to other parts of the body.

Median OS for patients with ES-SCLC treated with current Standard-of-Care (SoC) therapies is approximately 12 to 13 months. Despite advances in treatment, outcomes for patients with ES-SCLC remain poor and risk of disease progression or recurrence remains high, underscoring the need for new therapies that can improve outcomes for patients facing this aggressive cancer.

GSK is focused on developing differentiated medicines for cancers where patients continue to face poor outcomes, treatment resistance, limited options or significant treatment burden. We focus where advances in science and technology offer the greatest opportunity to improve outcomes across hematological, lung, gastrointestinal, genitourinary and gynaecological cancers. Across multiple modalities, including targeted small molecules, ADCs and immunotherapies, GSK applies deep expertise in cancer biology and immune system science to develop differentiated medicines designed to deliver durable responses, overcome resistance and reduce treatment burden.