STCube said Thursday it received approval from the Ministry of Food and Drug Safety (MFDS) for its investigational new drug (IND) application to initiate a phase 1b/2 clinical trial of nelmastobart, a novel immune checkpoint inhibitor targeting BTN1A1, in patients with metastatic colorectal cancer.
STCube has received IND approval in Korea to initiate a phase 1b/2 trial of nelmastobart, a first-in-class BTN1A1-targeting immunotherapy, in patients with metastatic colorectal cancer. (Screen capture of STCube homepage)
Nelmastobart is the first-in-class immunotherapy designed to inhibit BTN1A1, a protein known to be mutually exclusive with PD-L1 expression. Unlike conventional immune checkpoint inhibitors targeting PD-L1, nelmastobart is expected to offer a new therapeutic option for patients who are unresponsive or resistant to current treatments.
“We received IND approval earlier than expected,” a company official said. “We systematically designed the clinical trial in line with regulatory guidance and have prepared thoroughly. We will do our utmost to ensure a smooth and timely patient recruitment and dosing process.”
The trial will be conducted at five university hospitals across Korea, with Institutional Review Board (IRB) review already underway at Korea University Anam Hospital. STCube plans to promptly submit IRB applications to the remaining hospitals to accelerate the clinical process.
The study will evaluate the safety and efficacy of nelmastobart in combination with TAS-102 and bevacizumab in patients with metastatic or recurrent colorectal cancer who are refractory or intolerant to oxaliplatin- and irinotecan-based chemotherapy. The company submitted its IND to the MFDS last month.
Notably, the trial will focus on BTN1A1-positive patients, representing a biomarker-based approach that distinguishes it from prior studies. Based on previous findings showing a correlation between BTN1A1 expression and drug responsiveness, STCube aims to enhance therapeutic outcomes by selecting patients more likely to benefit from nelmastobart.
During the phase 1b study, which will enroll at least six patients, the trial will determine the maximum tolerated dose (MTD) and recommended phase 2 dose (RP2D) of the combination therapy.
Dose-limiting toxicity (DLT) assessments are expected to be completed within the first half of this year.
In the phase 2 trial, involving a minimum of 52 patients with a BTN1A1 tumor proportion score (TPS) of 50 percent or higher, progression-free survival (PFS) will be the primary endpoint.
With this trial, STCube aims to demonstrate the clinical value of BTN1A1-targeted immunotherapy as a potential breakthrough for patients who have reached the limits of existing checkpoint inhibitors.
BTN1A1 TPS ≥50 percent is found in over 30 percent of colorectal cancer patients and is also highly expressed in several solid tumors, including lung cancer.
“This trial represents a critical opportunity to validate BTN1A1 as a novel immuno-oncology target and biomarker, as well as to highlight the therapeutic potential of Nelmastobart,” said STCube CEO Jung Hyun-jin. “Given the favorable pharmacological data from previous studies, we also expect to swiftly complete the IRB approval process.”