Kelun-Biotech Unveils First-in-Human Results for SKB500 at ASCO 2026
During the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting, Kelun-Biotech revealed significant findings from their first-in-human study of SKB500, a novel B7-H3 antibody-drug conjugate (ADC). This innovative treatment aims to target advanced solid tumors and is anticipated to offer new hope in cancer therapy. The study, led by Professor Liu Haifeng from Jilin Provincial Cancer Hospital, focused on a range of diverse cancers, including small cell lung cancer (SCLC), esophageal squamous cell carcinoma (ESCC), head and neck squamous cell carcinoma (HNSCC), colorectal cancer (CRC), and neuroendocrine carcinoma (NEC).
SKB500 has been designed with a high-affinity antibody, optimized for enhanced endocytosis and minimal Fc effector function by utilizing a cleavable hydrophilic linker paired with a moderately toxic payload. In this Phase I study, researchers meticulously escalated doses across three stages: dose escalation, dose expansion, and indication expansion, ultimately enrolling 192 patients. Participants received doses ranging from 2 to 18 mg/kg every three weeks, with some patients specifically receiving 12 mg/kg and 16 mg/kg. Efficacy results highlighted promising antitumor activity across several solid tumor types, with overall objective response rates (ORR) and disease control rates (DCR) demonstrating substantial therapeutic potential.
As of the end of March 2026, of 124 patients who were treated with 12 mg/kg of SKB500 and had a minimum of six weeks of follow-up, the ORR reached an impressive 42.7%. Notably, patient subgroup analyses illustrated strong outcomes for those suffering from SCLC; 40 patients displayed an ORR of 65.0%, with a median progression-free survival (mPFS) of 7.2 months. Furthermore, the incidence of disease control within this subgroup soared to 95%. Similar yet promising responses also emerged among patients with other tumor types, such as ESCC, where a 54.1% ORR was documented.
In terms of safety, the findings were equally encouraging, showing that the 12 mg/kg dose yielded a more favorable safety profile compared to the 16 mg/kg group. The lower incidence of grade ≥3 treatment-related adverse events (TRAEs) and serious adverse events (TRSAEs) further underscores the manageable safety of SKB500. Hematological events were the most common side effects, with 32.3% of patients in the 12 mg/kg cohort experiencing grade ≥3 TRAEs. Importantly, there were no treatment-related deaths, and permanent discontinuation was rare.
Professor Liu Haifeng remarked on the significance of these findings, asserting that the favorable efficacy and safety profile of SKB500 indicates its therapeutic potential across multiple solid tumors, particularly in treating aggressive SCLC, which currently has limited treatment options. He emphasized the study's results as a solid foundation for further clinical development, with hopes of validating SKB500's clinical value in subsequent trials.
SKB500 is a cutting-edge ADC that was developed by Kelun-Biotech using their proprietary OptiDC™ platform, designed with a site-specific cleavable linker and an effective topoisomerase I inhibitor. Following its successful first-in-human results, a Phase II exploratory study is ongoing in China, aimed at assessing SKB500's efficacy in combination with immunotherapy or chemotherapy for extensive-stage small cell lung cancer as a first-line treatment.
Kelun-Biotech is dedicated to advancing innovative drug development, focusing on addressing significant unmet medical needs in both China and globally. With over 30 key projects in development and a commitment to establishing itself as a leading force in the field of innovative pharmaceuticals, Kelun-Biotech continues its pursuit of meaningful solutions for various diseases.
SKB500 has been designed with a high-affinity antibody, optimized for enhanced endocytosis and minimal Fc effector function by utilizing a cleavable hydrophilic linker paired with a moderately toxic payload. In this Phase I study, researchers meticulously escalated doses across three stages: dose escalation, dose expansion, and indication expansion, ultimately enrolling 192 patients. Participants received doses ranging from 2 to 18 mg/kg every three weeks, with some patients specifically receiving 12 mg/kg and 16 mg/kg. Efficacy results highlighted promising antitumor activity across several solid tumor types, with overall objective response rates (ORR) and disease control rates (DCR) demonstrating substantial therapeutic potential.
As of the end of March 2026, of 124 patients who were treated with 12 mg/kg of SKB500 and had a minimum of six weeks of follow-up, the ORR reached an impressive 42.7%. Notably, patient subgroup analyses illustrated strong outcomes for those suffering from SCLC; 40 patients displayed an ORR of 65.0%, with a median progression-free survival (mPFS) of 7.2 months. Furthermore, the incidence of disease control within this subgroup soared to 95%. Similar yet promising responses also emerged among patients with other tumor types, such as ESCC, where a 54.1% ORR was documented.
In terms of safety, the findings were equally encouraging, showing that the 12 mg/kg dose yielded a more favorable safety profile compared to the 16 mg/kg group. The lower incidence of grade ≥3 treatment-related adverse events (TRAEs) and serious adverse events (TRSAEs) further underscores the manageable safety of SKB500. Hematological events were the most common side effects, with 32.3% of patients in the 12 mg/kg cohort experiencing grade ≥3 TRAEs. Importantly, there were no treatment-related deaths, and permanent discontinuation was rare.
Professor Liu Haifeng remarked on the significance of these findings, asserting that the favorable efficacy and safety profile of SKB500 indicates its therapeutic potential across multiple solid tumors, particularly in treating aggressive SCLC, which currently has limited treatment options. He emphasized the study's results as a solid foundation for further clinical development, with hopes of validating SKB500's clinical value in subsequent trials.
SKB500 is a cutting-edge ADC that was developed by Kelun-Biotech using their proprietary OptiDC™ platform, designed with a site-specific cleavable linker and an effective topoisomerase I inhibitor. Following its successful first-in-human results, a Phase II exploratory study is ongoing in China, aimed at assessing SKB500's efficacy in combination with immunotherapy or chemotherapy for extensive-stage small cell lung cancer as a first-line treatment.
Kelun-Biotech is dedicated to advancing innovative drug development, focusing on addressing significant unmet medical needs in both China and globally. With over 30 key projects in development and a commitment to establishing itself as a leading force in the field of innovative pharmaceuticals, Kelun-Biotech continues its pursuit of meaningful solutions for various diseases.
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