SHANGHAI, October 28, 2026 — Hansoh Pharmaceutical Group Co., Ltd. ("Hansoh Pharma," 03692.HK) today announced that preliminary results from the Phase 1 clinical study of HS-20108 were presented in a poster session at the 2026 Annual Meeting of the European Society for Medical Oncology (ESMO). HS-20108 demonstrated a manageable safety profile and preliminary efficacy in the advanced solid tumor population, with particularly pronounced anti-tumor activity in small cell lung cancer (SCLC) patients who have received prior platinum-based chemotherapy.

HS-20108 is a proprietary antibody-drug conjugate (ADC) targeting SEZ6, developed by Hansoh Pharma, comprising a fully human anti-SEZ6 monoclonal antibody conjugated to a topoisomerase I inhibitor (TOP1i) payload via a linker. It is currently under clinical development for indications including small cell lung cancer (SCLC) and neuroendocrine tumors (NEN). The current ESMO 2026 data disclose the preliminary monotherapy results of this drug in patients with advanced solid tumors.

Details of the Poster Presentation

• Poster Title: Phase 1 Study of HS-20108, a SEZ6-Targeting Antibody-Drug Conjugate, in Patients with Advanced Solid Tumors

• Presentation Format: Poster

• FPN: 3814P

• Date/Time: Mon. 26.10.2026 (12:00-12:45) CET

• Presenter: Prof. Shengxiang Ren, Shanghai Pulmonary Hospital

About the HS-20108-101 Study

HS-20108-101 (NCT06936735) is a first-in-human, multicenter, open-label Phase 1 trial conducted in China evaluating the safety, tolerability, pharmacokinetic (PK) profile, and preliminary anti-tumor activity of HS-20108 in patients with advanced solid tumors. The study comprises a Phase 1a dose-escalation phase (2.0-6.0 mg/kg, administered intravenously once every 3 weeks) and a Phase 1b dose-expansion phase. The primary endpoints are the maximum tolerated dose (MTD)/maximum administered dose (MAD) and the objective response rate (ORR) assessed by investigators per RECIST v1.1.

As of the data cutoff (12 August 2026), a total of 96 patients with advanced solid tumors were enrolled, with a median follow-up time of 4.53 months (range: 0.1-14.5 months). The data in the advanced solid tumor population are as follows:

Encouraging anti-tumor activity:

• Tumor responses were observed across all dose groups (2.0-6.0 mg/kg, N=90): the unconfirmed ORR (uORR) was 51.1%, the confirmed ORR (cORR) was 41.1%, and the disease control rate (DCR) was 95.6%;

• Efficacy was particularly pronounced in SCLC patients (4.0/5.0 mg/kg cohorts, N=55): uORR was 65.4%/58.6%, cORR was 57.7%/44.8%, and DCR was 100.0%/96.6%, respectively.

• In SCLC patients who had received prior first-line therapy (i.e., second-line therapy) (4.0/5.0 mg/kg cohorts, N=33): uORR reached 75.0%/64.7%, cORR was 68.8%/52.9%, and the DCR in both dose cohorts was 100.0%, further supporting the treatment potential of HS-20108 in second-line SCLC.

Manageable safety:

• Only one dose-limiting toxicity (DLT) was reported (in the 6.0 mg/kg cohort, grade 4 thrombocytopenia); no infusion-related reactions were reported;

• Grade ≥3 treatment-related adverse events (TRAEs) were mainly hematologic and gastrointestinal events, all of which were manageable and resolved rapidly following treatment;

• One SCLC patient reported grade 3 treatment-related interstitial lung disease (ILD; this event was also considered possibly related to prior immuno-oncology therapy). One grade 5 adverse event was reported (preferred term: disease progression);

• Overall, HS-20108 demonstrated a manageable safety profile in patients with advanced solid tumors, and the safety profile in SCLC patients was generally consistent with that of the overall population.

Hansoh Pharma will continue to be driven by patient needs, deepening the clinical layout of HS-20108 across multiple tumor types, multiple lines of therapy, and various combination regimens, fully exploiting the therapeutic potential of the SEZ6-targeting ADC, advancing Chinese innovation to the world, and providing more effective and accessible disease solutions for patients globally.

About Small Cell Lung Cancer

In 2022, an estimated 1.06 million new cases of lung cancer and 733,300 lung cancer-related deaths were reported in China, making lung cancer the most common cancer and the leading cause of cancer-related mortality in the country ^[1]. Small cell lung cancer (SCLC) accounts for approximately 10%–5% of all lung cancer cases ^[2] and is characterized by its highly aggressive nature, early development of widespread metastases, high risk of recurrence, and poor prognosis ^[3].

SCLC is broadly classified into limited-stage disease (LS-SCLC) and extensive-stage disease (ES-SCLC). Treatment for LS-SCLC may include surgery and concurrent chemoradiotherapy; however, the 5-year survival rate remains only approximately 30%–35% ^[4]. Approximately 60%–70% of patients with SCLC are diagnosed with extensive-stage disease, for which palliative systemic therapy, primarily chemotherapy, is the mainstay of treatment. Patients with ES-SCLC have a particularly poor prognosis, with a median overall survival of only 7–12 months ^[5] and a 2-year survival rate of approximately 22% ^[6], underscoring the high unmet medical need and the urgency of developing innovative therapies.

References

[1] Zheng RS, Chen R, Han BF, et al. Cancer incidence and mortality in China, 2022. Chinese Journal of Oncology. 2024;46(3):221-231.

[2] Kim SY, Park HS, Chiang AC. Small Cell Lung Cancer: A Review. JAMA. 2025 Jun 3;333(21):1906-1917.

[3] Rudin CM, Brambilla E, Faivre-Finn C, Sage J. Small-cell lung cancer. Nat Rev Dis Primers. 2021;7(1):3.

[4] Higgins KA, Gorgens S, Sudmeier LJ, Faivre-Finn C. Recent developments in limited stage small cell lung cancer. Transl Lung Cancer Res. 2019;8(Suppl 2): S147-S152.

[5] Wang S, Zimmermann S, Parikh K, Mansfield AS, Adjei AA. Current Diagnosis and Management of Small-Cell Lung Cancer. Mayo Clin Proc. 2019;94(8):1599-1622.

[6] Rudin CM, Brambilla E, Faivre-Finn C, Sage J. Small-cell lung cancer. Nat Rev Dis Primers. 2021;7(1):3.