CHENGDU, China, May 29, 2026
Kelun-Biotech has presented pivotal Phase II clinical trial results for its next-generation selective RET inhibitor, lunbotinib fumarate (A400/EP0031), at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago. The study demonstrated robust and durable clinical activity in patients with RET fusion-positive non-small cell lung cancer (NSCLC), including those with central nervous system (CNS) metastases. The results come as the company announced that the New Drug Application (NDA) for lunbotinib fumarate has been accepted for review by China’s National Medical Products Administration (NMPA), bringing the therapy one step closer to commercialization. The latest findings position lunbotinib as a promising treatment candidate in a patient population that continues to face limited targeted therapy options despite significant advances in precision oncology.
Pivotal Phase II Study Delivers High Response Rates
The pivotal study enrolled 163 patients with advanced RET fusion-positive NSCLC, including 92 treatment-naïve patients and 71 previously treated patients who had received platinum-based chemotherapy and immunotherapy. Results assessed by an Independent Review Committee demonstrated an impressive objective response rate (ORR) of 81.3% in treatment-naïve patients and 87.1% ORR in pre-treated patients. Notably, the median duration of response and median progression-free survival had not yet been reached in the treatment-naïve population, indicating sustained and durable clinical benefit.
Among previously treated patients, the therapy achieved a median duration of response of 25.7 months and median progression-free survival of 27.5 months, highlighting the drug’s potential to provide long-term disease control. These outcomes compare favorably with existing treatment approaches and reinforce the growing importance of selective RET inhibition in the management of molecularly defined lung cancers.
Strong Intracranial Activity Addresses Critical Patient Need
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One of the most significant findings from the trial was the therapy’s effectiveness in patients with brain metastases, a common and challenging complication of advanced NSCLC. Among 40 patients presenting with CNS metastases at baseline, lunbotinib achieved an intracranial complete response rate of 30% and an exceptional disease control rate of 92.5%. CNS involvement remains a major cause of disease progression and reduced quality of life in lung cancer patients, making therapies with strong brain penetration highly valuable.
Investigators noted that the impressive intracranial activity observed in the study could represent an important clinical advantage, particularly for patients whose disease has spread to the central nervous system. The results suggest that lunbotinib may offer comprehensive disease control both systemically and within the brain, potentially addressing one of the most difficult treatment challenges in RET-positive lung cancer management.
Favorable Safety Profile Supports Regulatory Advancement
Beyond efficacy, lunbotinib demonstrated a highly manageable safety profile. Treatment-related adverse events were predominantly Grade 1 or Grade 2, while the rate of permanent treatment discontinuation due to adverse events was only 1.2%. Importantly, investigators reported no treatment-related deaths and no unexpected safety concerns during the study. The favorable tolerability profile strengthens confidence in the therapy’s suitability for long-term treatment and supports ongoing regulatory review activities.
Kelun-Biotech is also advancing global development efforts through partnerships and international clinical programs, including an ongoing Phase II study cleared by the U.S. Food and Drug Administration (FDA) and currently recruiting patients across the United States, Europe, the United Kingdom, and the United Arab Emirates. As precision medicine continues to transform lung cancer treatment, the pivotal Phase II data presented at ASCO 2026 position lunbotinib fumarate as a potentially important new targeted therapy for patients with RET fusion-positive NSCLC, offering durable responses, meaningful intracranial efficacy, and a favorable safety profile.
Source: Kelun-Biotech press release
