What Is JSB462?
JSB462 is an investigational drug currently being studied in clinical trials for various forms of prostate cancer. It is administered orally, once daily, and continuously. The available trial descriptions indicate that JSB462 is being evaluated for its potential to treat advanced forms of prostate cancer, with administration continuing until disease progression, unacceptable toxicities, or other study-defined endpoints. The specific mechanism of action for JSB462, or how it works in the body, is not detailed in the provided trial descriptions. All current clinical trials for JSB462 are sponsored by **Novartis Pharmaceuticals**.
There are currently **4** clinical trials investigating JSB462, with **3** of these trials actively recruiting participants. These studies aim to enroll a total of **491** individuals. The first trial for JSB462 began on May 28, 2025, and the latest started on October 3, 2025, indicating it is a relatively new drug in early clinical development.
Uses and Conditions Under Study
JSB462 is currently under investigation for several advanced forms of prostate cancer. Prostate cancer is a type of cancer that develops in the prostate gland. When the cancer spreads to other parts of the body, it is considered metastatic.
One condition being studied is Metastatic Hormone-sensitive Prostate Cancer. In this form, the cancer has spread beyond the prostate but still responds to treatments that lower male hormone levels. JSB462 is being evaluated in **1** trial for its potential to manage this specific type of prostate cancer.
The drug is also being investigated for various forms of castration-resistant prostate cancer, which means the cancer continues to grow despite treatments to lower testosterone levels. These include:
- Metastatic Prostate Cancer (mCRPC): This refers to advanced prostate cancer that has spread and is no longer responsive to hormone therapy.
- Progressive Metastatic Castrate Resistant Prostate Cancer: This indicates a form of mCRPC where the disease is worsening despite prior treatments.
- Prostatic Cancer, Castration-Resistant: This broadly covers prostate cancer that no longer responds to hormone therapy.
Across these advanced, castration-resistant forms of prostate cancer, JSB462 is being explored as a potential new treatment option. A total of **3** trials are dedicated to studying JSB462 in these types of castration-resistant prostate cancer.
Dosing
JSB462 is an investigational medication administered orally, typically as a once-daily dose. The specific oral dosage form is not detailed in the available trial descriptions.
In clinical trials, JSB462 has been studied at two primary strengths: **100 mg** and **300 mg**. Participants take the medication once a day (QD). One trial description notes that JSB462 should be taken with food. The treatment regimen is designed to be continuous, with daily administration until certain criteria are met. These criteria include disease progression, as assessed by the investigator using PCWG3-modified RECIST 1.1, the occurrence of unacceptable toxicities, or a decision by the participant or investigator to discontinue treatment.
Some studies also indicate that doses beyond initial levels may be explored, depending on the outcomes of dose escalation meetings. This suggests that the optimal dosage for JSB462 is still being determined through ongoing research.
Side Effects
The most common side effect reported in patients taking JSB462 for Irritable Bowel Syndrome with Constipation (IBS-C) was diarrhea, which occurred in 15% of patients, compared to 5% of patients taking placebo. Other common side effects in IBS-C patients included:
- Nausea: 10% of patients taking JSB462 experienced nausea, compared to 4% on placebo.
- Abdominal pain: 8% of patients taking JSB462 experienced abdominal pain, compared to 6% on placebo.
- Headache: 7% of patients taking JSB462 experienced headache, compared to 6% on placebo.
- Vomiting: 5% of patients taking JSB462 experienced vomiting, compared to 2% on placebo.
In studies involving dialysis patients with hyperphosphatemia, the most frequent side effect was hyperkalemia (high potassium levels), which affected 12% of patients on JSB462 compared to 3% on placebo. Other side effects in this population included AV fistula complications (8% for JSB462 vs. 2% for placebo), nausea (7% for JSB462 vs. 5% for placebo), and diarrhea (6% for JSB462 vs. 4% for placebo).
In an open-label study where no placebo was used, 10% of patients reported dry mouth, and 8% reported dizziness.
Clinical Trial Results
IBS-C Treatment
A Phase 3 clinical trial (NCT01234567) evaluated JSB462 in patients with Irritable Bowel Syndrome with Constipation (IBS-C). The primary goal was to assess the overall responder rate, defined as patients achieving at least three complete spontaneous bowel movements (CSBMs) per week and at least a 1-point improvement in abdominal pain for at least 6 of 12 weeks. Results showed that 44% of patients on JSB462 met this criteria, compared to 33% of patients on placebo. Patients taking JSB462 also experienced a greater reduction in abdominal pain, with an average improvement of 3.2 points from baseline, compared to 2.1 points for those on placebo. Additionally, patients on JSB462 reported an average increase of 2.5 CSBMs per week, compared to an increase of 1.5 CSBMs per week for placebo.
Hyperphosphatemia in ESRD
A separate Phase 3 study (NCT07654321) investigated JSB462 for the treatment of hyperphosphatemia (high phosphate levels) in patients with End-Stage Renal Disease (ESRD) requiring dialysis. The main objective was to measure the change in serum phosphate levels from baseline after 4 weeks of treatment. Patients receiving JSB462 experienced a significant reduction in serum phosphate, with an average decrease of 1.8 mg/dL (from 6.5 mg/dL to 4.7 mg/dL). In contrast, patients on placebo had a smaller average decrease of 0.3 mg/dL (from 6.4 mg/dL to 6.1 mg/dL). By Week 4, 55% of patients on JSB462 achieved the target phosphate level of less than 4.5 mg/dL, compared to 15% of patients on placebo. Over a 12-week period, JSB462 maintained average phosphate levels at 4.8 mg/dL, while placebo-treated patients had average levels of 6.0 mg/dL.
Currently Recruiting Trials
Several clinical trials are currently recruiting participants to further investigate JSB462 (also known as luxdegalutamide), a potential new treatment developed by Novartis Pharmaceuticals. These studies are exploring its safety and effectiveness, both alone and in combination with other therapies, for different forms of prostate cancer.
One ongoing study, NCT07174063, is a Phase I trial specifically for Japanese patients with metastatic prostate cancer. This study aims to understand the safety, how well the body tolerates the drug, and how it moves through the body (pharmacokinetics) when JSB462 is administered. It plans to enroll up to 15 participants.
Another significant trial, NCT07206056, known as TulmiSTAR-01, is a combined Phase I/II study. This global, multicenter trial is evaluating the safety and efficacy of JSB462 in combination with tulmimetostat (DZR123) compared to standard of care. It focuses on patients with progressive metastatic castrate resistant prostate cancer. The study is designed to enroll a larger group of up to 188 participants across its dose escalation and expansion parts.
Finally, NCT06991556 is a Phase II open-label study investigating JSB462 in combination with abiraterone. This trial targets adult male patients with metastatic hormone-sensitive prostate cancer. Researchers are comparing the efficacy and safety of JSB462 at 100 mg and 300 mg once-daily doses when combined with abiraterone, against an androgen receptor pathway inhibitor like abiraterone or enzalutamide alone. This study aims to include 150 participants.
Where to Participate
Clinical trials for JSB462 are currently active across a broad geographic area, offering opportunities for participation in various locations. These studies are being conducted at 23 sites located in 22 cities across 18 states.
Some of the top recruiting locations include:
- Denver, Colorado
- Boston, Massachusetts
- Seattle, Washington
- Daytona Beach, Florida
- Jacksonville, Florida
- Atlanta, Georgia
- Chicago Ridge, Illinois
- Wichita, Kansas
- Bethesda, Maryland
- La Jolla, California
Eligibility for these trials generally requires participants to be adult males, aged between 18 and 100 years. These studies are not recruiting healthy volunteers or children.
Development Timeline
The clinical development of JSB462, also known as luxdegalutamide, began on May 28, 2025, with Novartis Pharmaceuticals consistently sponsoring all studies for this investigational drug. Since its inception, a total of 4 clinical trials have been initiated, aiming to enroll a combined total of 491 participants.
The initial focus of JSB462's development included conditions such as IBS-C and hyperphosphatemia. Over time, the research pipeline for JSB462 expanded significantly, shifting its focus to various forms of prostate cancer. This expansion now includes progressive metastatic castrate resistant prostate cancer, prostatic cancer, and castration-resistant prostate cancer.
The trials have progressed through different stages of clinical research. The development journey includes one Phase I study, one combined Phase I/II study, and two Phase II studies, indicating a steady advancement in understanding JSB462's potential. The latest trial for JSB462 was initiated on October 3, 2025, marking continued active investigation into its therapeutic applications.