STCube Starts Dosing in MSS Colorectal Cancer Researcher-Led Phase 2 Trial... "Phase 1b Results to Be Announced in August"

STCube announced on the 30th that it has started dosing the first patient in the Phase 2 portion of the investigator-initiated Phase 1b/2 clinical trial of its immune checkpoint inhibitor candidate Nelmastovat (hSTC810) for metastatic colorectal cancer.

STCube is conducting an investigator-initiated Phase 1b/2 clinical trial to evaluate the efficacy and safety of Nelmastovat in combination with capecitabine (a standard treatment) as a third-line therapy for MSS (microsatellite stable) colorectal cancer.

In the dose-escalation phase of the Phase 1b trial, safety and efficacy were confirmed in 12 patients. Currently, follow-up data on the Phase 1b patients are being compiled, and the first interim analysis results are scheduled to be released in August.

Subsequently, in the Phase 2 stage, 39 patients will be recruited. The recommended Phase 2 dose (RP2D) was established as Nelmastovat 800 mg and capecitabine 1000 mg/m2, with no drug-related adverse reactions and expected high efficacy. The primary goal is to improve the median progression-free survival (PFS) of the patients.

An STCube representative stated, “For patients with advanced colorectal cancer who have failed all previous standard treatments including chemotherapy, progression-free survival (the period during which the cancer does not worsen after treatment) is the most important evaluation metric in cancer therapy. Even an extension of survival by one or two months represents a significant improvement in quality of life for terminal cancer patients and can be a meaningful figure that leads to final drug approval.”

In fact, in November last year, Takeda Pharmaceutical’s Pralsetinib (brand name Pralsetra) received approval from the U.S. Food and Drug Administration (FDA) as a third-line or later treatment for colorectal cancer after Phase 3 clinical trial results showed significant improvements in the primary and secondary endpoints of overall survival (OS) and progression-free survival compared to placebo.

The median progression-free survival for Pralsetinib was 3.7 months, an increase of 1.9 months compared to the placebo group (1.8 months), and the median overall survival was 7.4 months, 2.6 months longer than the placebo group (4.8 months).

The greatest challenges in cancer treatment are “recurrence” and “metastasis.” Colorectal cancer ranks third in incidence and second in mortality worldwide, with liver metastasis occurring in 70% of patients, leading to a sharp decline in survival rates. Particularly, there are currently no immune checkpoint inhibitors proven effective in MSS colorectal cancer, which accounts for 95% of metastatic colorectal cancer cases.

BTN1A1, the target of Nelmastovat, is a novel immune checkpoint protein discovered by STCube. Through Phase 1 clinical trials, STCube confirmed that BTN1A1 is strongly expressed in dormant cancer cells (slow-growing or hidden cancer cells) involved in cancer recurrence and metastasis. Accordingly, to simultaneously induce the death of dormant cancer cells and rapidly proliferating cancer cells in the early stages, STCube is conducting a Phase 1b/2 trial combining Nelmastovat with chemotherapy.

A company representative said, “Since indicators exceeding those of existing treatments are currently being observed in the Nelmastovat combination therapy, the colorectal cancer clinical trial is progressing rapidly and is expected to be completed within this year. Our clinical data has attracted significant interest both domestically and internationally, including from global big pharma companies, and we are advancing discussions regarding licensing out (L/O) and other collaborations.”

This content was produced with the assistance of AI translation services.