[Edaily Reporter YU JIN-HEE ] #PenetriumBio presented preclinical data at the American College of Rheumatology (ACR) conference demonstrating the mechanism for controlling “pseudo-resistance,” a key strategy in cancer treatment. Following the recent application to extend treatment for the first patient in a domestic prostate cancer clinical trial, the company has now secured scientific evidence, which is expected to give momentum to its global clinical trials for combination cancer therapies.

PenetriumBio announced on the 12th that Professor John Isaacs of Newcastle University in the UK presented the results of preclinical studies on Penetrium’s research formulation (CP-RhA01) at “ACR Convergence 2026,” held in Orlando, Florida, on the 9th (local time).

Professor Isaac led this study as the first author, with Professor Choi Jin-ho of Dankook University and Jin Geun-woo, CEO of PenetriumBio, participating as co-authors.

The academic community is paying close attention to this presentation because the tumor microenvironment (TME) in solid tumors and the pathological synovial environment in rheumatoid arthritis share the same pathological characteristic known as the “pathological microenvironment.” In both diseases, pathological fibroblasts and extracellular matrix (ECM) accumulate abnormally, obstructing drug delivery and the access of immune cells, and reducing the efficacy of existing treatments.

PenetriumBio defines this phenomenon—where drugs fail to function properly due to the pathological microenvironment—as “stromal pseudo-resistance” and has been developing therapeutic strategies to normalize it.

In this study, the research team administered Penitrium in combination with the standard treatment, methotrexate (MTX), to an animal model of arthritis. As a result, arthritis markers showed marked improvement compared to the group treated with the standard therapy alone, and the formation of “pannus”—pathological stromal tissue that destroys joints—was significantly suppressed. In particular, markers of pathological fibroblast activity (FAPα and α-SMA) and extracellular matrix-related markers were found to have decreased significantly.

This demonstrates at the molecular and metabolic levels that, by normalizing the pathological matrix environment itself—rather than merely suppressing inflammation—it is possible to restore the therapeutic response to existing drugs.

This preclinical mechanism aligns with the progress of the Phase 1 clinical trial for metastatic castration-resistant prostate cancer currently underway at Seoul National University Hospital by HYUNDAI BIOSCIENCE CO., LTD. The first patient, who began treatment last August under the leadership of Professor Jeong Chang-wook of the Department of Urology at Seoul National University Hospital, had not responded to existing hormone therapies; however, after 12 weeks of combination therapy with Penitrium (600 mg daily) and the existing hormone-targeted therapy “enzalutamide” for 12 weeks. Based on the attending physician’s assessment, an application for a 6-month (180-day) individual treatment-use authorization was submitted to the Ministry of Food and Drug Safety on the 6th.

Building on these achievements, PenetriumBio plans to expand clinical validation beyond prostate cancer to various intractable solid tumors. Previously, in September, the company received approval from the U.S. Food and Drug Administration (FDA) for an Investigational New Drug (IND) application for a Phase 2a clinical trial of Penetrium in combination therapy for patients with recurrent or refractory advanced solid tumors.

Cho Won-dong, Chairman of PenetriumBio, stated, “This ACR presentation scientifically validates the principle of controlling pseudo-resistance in the pathological microenvironment—the common therapeutic mechanism for cancer and rheumatoid arthritis—which we presented at the Seoul International Symposium last January,” and He emphasized, “Based on the real-world dosing experience and mechanistic evidence accumulating from domestic prostate cancer clinical trials, we will expand clinical development both domestically and internationally to various cancer types and autoimmune diseases to demonstrate the value of this new combination anticancer therapy.”