FDA Grants Fast-Track for ISB 2001: A Trispecific Antibody for Relapsed/Refractory Multiple Myeloma

 ISB 2001 is a new tri-specific T-cell engager being tested in early clinical trials for relapsed or refractory multiple myeloma. Based on phase 1 study results showing the treatment’s safety, the FDA has granted a fast-track designation. This designation is given to promising new therapies that address unmet medical needs or serious diseases.

Targeting Multiple Myeloma in a New Way

ISB 2001 is designed to activate the immune system against multiple myeloma cells by engaging three targets at once: BCMA, CD38, which are proteins on the surface of myeloma cells, and CD3, a marker on T cells.

Unlike older therapies that target only one or two of these proteins, ISB 2001 is engineered to bind even when the cancer cells have low levels of the target proteins. Its structure also helps reduce unwanted effects on healthy tissues. This design may reduce side effects and maintain strong anti-myeloma activity.

The Study That Granted FDA Fast-Track

The phase 1 study tested ISB 2001 in patients with relapsed or refractory multiple myeloma. Participants had already received at least three types of therapy, including a proteasome inhibitor, an immunomodulatory agent, and an anti-CD38 antibody.

Patients received ISB 2001 once a week through a subcutaneous injection, and gradually increased the dose. Among patients who received doses ranging from 50 to 1200 micrograms per kilogram, the overall response rate was 83%. 

Long-Lasting Effect with Fewer Injections

One of the goals of the study was to understand how the body processes ISB 2001. The medication had a long half-life, which could allow for less frequent dosing in future treatment plans. Additionally, the time to first response was relatively short with a median of 36 days meaning patients began seeing benefits within the first month of treatment.

A key concern with newer immunotherapies is how well patients tolerate them. In this trial, no dose-limiting toxicities were observed, even at higher doses.

The most common side effects were:

• Cytokine release syndrome (CRS), occurs in 75% of patients. This is an immune-related reaction that was mostly mild (grade 1), with only two cases reaching grade 2. It appeared around 3 days after treatment and lasted about 2 days, on average. 
• Injection site reactions were seen in 60% of patients.
• Infection and blood-related side effects remained low, making the therapy potentially more manageable for patients with weakened immune system.

Additionally, no cases of brain-related side effects, which is often a concern with similar therapies.

What’s Next for ISB 2001?

FDA Fast-Track designation is given to treatments that address unmet medical needs, potentially accelerating their development.. The dose-escalation part of the study has been completed, and full results will be shared at the 2025 American Society of Clinical Oncology (ASCO) Annual Meeting. The study is now in its dose-expansion phase, where more patients will be enrolled to further evaluate the treatment’s effects. 

Stay tuned for updates from the ASCO conference on the HealthTree News site.

STAY TUNED

For people with relapsed or refractory multiple myeloma, treatment options can become limited over time. In response to the need for more options for those who have tried many different treatments, ISB 2001 offers a different approach by targeting multiple markers on myeloma cells while diminishing side effects. 

You can learn more about bispecific antibodies and clinical trial endpoints in HealthTree’s patient guides. 

BISPECIFIC ANTIBODIES

CLINICAL TRIAL GUIDE

Sources:

• https://www.sciencedirect.com/science/article/pii/S000649712403773X 

• https://www.onclive.com/view/fda-grants-fast-track-designation-to-isb-2001-in-relapsed-refractory-multiple-myeloma