Suzhou, China, March 25th, 2026—CStone Pharmaceuticals (“CStone,” HKEX: 2616), an innovation-driven biopharmaceutical company focused on the research and development of therapies for oncology, immunology, inflammation, and other key disease areas, today announced that its core commercial product, sugemalimab, has received a [I, A] recommendation in the European Society for Medical Oncology (ESMO) Early and Locally Advanced Non-Small-Cell Lung Cancer Living Guideline. This recommendation support sugemalimab for consolidation therapy in patients with unresectable Stage III non-small cell lung cancer (NSCLC) who have not progressed after concurrent or sequential chemoradiotherapy. This recommendation is expected to significantly facilitate market access for sugemalimab in the European Union and other regions, expanding patient reach - thus strengthening its global commercialization.

In February 2025, sugemalimab in combination with chemotherapy had received a [I, A] recommendation from the ESMO Non-Oncogene-Addicted Metastatic Non-Small-Cell Lung Cancer Living Guideline for the first-line treatment of both squamous and non-squamous metastatic (Stage IV) NSCLC. To date, both NSCLC indications for which sugemalimab is approved in the EU and UK are now included in ESMO guidelines, underscoring its recognized clinical value.

Guideline reference：https://www.esmo.org/guidelines/living-guidelines/esmo-living-guideline-early-and-locally-advanced-nsclc/management-of-early-and-locally-advanced-nsclc/management-of-unresectable-stage-iii-nsclc/therapy-for-unresectable-stage-iii-nsclc

As per the latest ESMO guideline update:

Sugemalimab consolidation therapy is recommended for patients with EGFR wild-type and no ALK or ROS1 genomic tumour aberrations, stage III NSCLC who have not progressed after concurrent or sequential chemoradiotherapy, for a duration of up to 24 months. This [I, A] recommendation applies to patients whose tumours express PD-L1 on ≥1% of tumour cells (TC) [ESMO-MCBS v2.0 score: 3; approved by European Medicines Agency (EMA)].

This recommendation is based on the results from the pivotal Phase III GEMSTONE-301 clinical trial, which demonstrated that sugemalimab provided a statistically significant improvement in progression-free survival (PFS) and a clinically meaningful extension in overall survival (OS) for patients with Stage III NSCLC."

To date, sugemalimab has secured four commercialization partnerships across Europe, the Middle East and Africa, and Latin America, covering more than 60 countries and regions. Market access applications have been approved or are under review in more than ten countries, as the product’s international commercialization continues to advance actively.

About Sugemalimab

The anti-PD-L1 monoclonal antibody sugemalimab was developed by CStone using OmniRat^® transgenic animal platform, which allows creation of fully human antibodies in one step. Sugemalimab is a fully human, full-length anti-PD-L1 immunoglobulin G4 (IgG4) monoclonal antibody, which may reduce the risk of immunogenicity and toxicity for patients, a unique advantage over similar drugs.

The EC and MHRA have approved sugemalimab for two indications:

• In combination with platinum-based chemotherapy for the first-line treatment of patients with metastatic NSCLC with no sensitizing EGFR mutations, or ALK, ROS1 or RET genomic tumor aberrations; and
• Monotherapy for adult patients with unresectable stage III NSCLC with PD-L1 expression on ≥1% of tumor cells and no sensitising EGFR mutations, or ALK, ROS1 genomic aberrations and whose disease has not progressed following platinum-based CRT.

The National Medical Products Administration (NMPA) of China has approved sugemalimab for five indications:

• In combination with chemotherapy as first-line treatment of patients with metastatic squamous and non-squamous NSCLC with no EGFR or ALK genomic tumor aberrations and metastatic squamous NSCLC;
• For the treatment of patients with unresectable Stage III NSCLC whose disease has not progressed following concurrent or sequential platinum-based CRT;
• For the treatment of patients with relapsed or refractory extranodal NK/T-cell lymphoma;
• In combination with fluorouracil and platinum-based chemotherapy as first-line treatment of patients with unresectable locally advanced, recurrent or metastatic ESCC; and
• In combination with fluoropyrimidine- and platinum-containing chemotherapy as first-line treatment for unresectable locally advanced or metastatic gastric or gastroesophageal junction (G/GEJ) adenocarcinoma with a PD-L1 expression CPS ≥5.

ESMO Guidelines recommend sugemalimab [I, A] for:

• In combination with platinum-doublet chemotherapy as first-line treatment for non-oncogene-addicted stage IV patients with squamous NSCLC, performance status (PS) 0-1, regardless of tumor PD-L1 status and without contraindications for immune checkpoint inhibitors (ICI);
• In combination with platinum-based chemotherapy as first-line treatment for patients with non-squamous NSCLC, PS 0-1, regardless of tumor PD-L1 status and without contraindications for ICI; and
• Consolidation therapy for up to 24 months in patients with stage III NSCLC, who are EGFR wild-type and lack ALK or ROS1 genomic aberrations, following concurrent or sequential chemoradiotherapy without disease progression.

About CStone

CStone (HKEX: 2616), established in late 2015, is an innovation-driven biopharmaceutical company focused on the research and development of therapies for oncology, immunology, inflammation, and other key disease areas. Dedicated to addressing patients’ unmet medical needs in China and globally, the Company has made significant strides since its inception. To date, the Company has successfully launched 4 innovative drugs and secured approvals for 21 new drug applications covering 9 indications. The company’s pipeline is balanced by 16 promising candidates, featuring antibody-drug conjugates (ADCs), multispecific antibodies, immunotherapies, and precision medicines. CStone also prides itself on a management team with comprehensive experiences and capabilities that span the entire drug development spectrum, from preclinical and translational research to clinical development, drug manufacturing, business development, and commercialization.

For more information about CStone, please visit: www.cstonepharma.com.

IR contact: ir@cstonepharma.com

PR contact: pr@cstonepharma.com

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