[Edaily Reporter NA EUN-KYUNG ] SillaJen, Inc.(215600)has confirmed initial antitumor effects in a Phase 1 clinical trial of its new anticancer drug candidate, “BAL0891,” currently under development. In an interim analysis of patients with advanced cancer who had undergone multiple prior anticancer treatments, the objective response rate (ORR) for the combination therapy with paclitaxel was 21.4%.

SillaJen, Inc. announced on the 26th that it presented interim results from the Phase 1 clinical trial of BAL0891 at the European Society for Medical Oncology (ESMO) Annual Congress held in Madrid, Spain.

This analysis was conducted on 54 patients enrolled in an ongoing Phase 1 clinical trial for advanced solid tumors in South Korea and the United States, who received BAL0891 either as a monotherapy or in combination with the anticancer drug paclitaxel. Of the total patient population, 81.5% had previously received at least two courses of systemic anticancer therapy, while 18.5% had received four or more courses of treatment.

In the paclitaxel combination group, the objective response rate (ORR) was 21.4%, and the disease control rate (DCR) was 78.6%. The ORR refers to the proportion of patients whose tumors shrank by a certain threshold or more, while the DCR includes patients whose tumors shrank or remained stable (no further growth).

In the monotherapy group, a complete response (CR)—defined as tumor disappearance—was observed in one bladder cancer patient. This response has been maintained for more than seven months. However, as these results represent an interim analysis from an early-phase clinical trial, validation involving additional patients is necessary to determine the actual therapeutic efficacy.

In terms of safety, neutropenia was reported as the primary drug-related adverse event. Neutrophils are a type of white blood cell that defends against infection; a decrease in their count can increase the risk of infection. SillaJen, Inc. explained that it was able to manage this side effect through dose adjustment and supportive care, and there were no cases of treatment discontinuation or death due to drug-related adverse events.

In this clinical trial, the maximum tolerated dose (MTD) for monotherapy and the recommended Phase 2 dose (RP2D) were also established. The maximum tolerated dose is the highest dose a patient can tolerate, while the recommended Phase 2 dose is the dose selected to evaluate safety and efficacy in subsequent trials.

BAL0891 is an anticancer candidate compound that SillaJen, Inc. acquired from the Swiss pharmaceutical company Basilia in September 2022. It is a dual inhibitor that simultaneously inhibits TTK and PLK1—enzymes that regulate cell division—thereby disrupting the normal division process of cancer cells and inducing cell death. At the time, SillaJen, Inc. signed a technology licensing agreement worth up to $335 million (approximately 440 billion won), including an upfront payment of $14 million (approximately 18.5 billion won). Subsequently, the company began Phase 1 clinical trials in the U.S. and South Korea in 2023, and in April of last year, it spent approximately 3.5 billion won to secure the patents and rights to BAL0891 held by the original developer, the Dutch company Crossfire. This move eliminated the obligation to pay milestone payments totaling up to approximately 300 billion won, which would have been due depending on future development stages.

Currently, SillaJen, Inc. is developing not only its existing solid tumor clinical trials but also combination therapy with the immunotherapy “Tisrelizumab” and monotherapy for patients with acute myeloid leukemia (AML). Last August, BAL0891 was designated as an orphan drug by the U.S. Food and Drug Administration (FDA) for the treatment of acute myeloid leukemia.

A SillaJen, Inc. official stated, “Through this interim analysis, we have established the maximum tolerated dose and the recommended Phase 2 dose for BAL0891 monotherapy, and confirmed initial antitumor activity in combination with paclitaxel,” adding, “We plan to finalize our follow-up clinical development plans and continue discussions on global partnerships.”