Iberdomide May Aid Efficacy of CAR T-Cell Therapy in Multiple Myeloma

Iberdomide may boost chimeric antigen receptor (CAR) T-cell expansion and functionality in patients with multiple myeloma, announced researchers at Mount Sinai and Bristol Myers Squibb today.¹

Their observations are part of a phase 1b/2a clinical trial for dose toleration, safety, pharmacokinetics, and efficacy of iberdomide as a monotherapy and in combination with other medications. The data were unveiled in a poster presentation at the 22nd International Myeloma Society Annual Meeting.

CAR T-cell therapy is a promising treatment for multiple myeloma, but some patients see only limited or temporary benefits "due to limited cell persistence and functional exhaustion," according to the poster. Iberdomide is a drug known to "[increase] proliferation, activation, and reduces T cell exhaustion," according to the abstract. This study looked at whether iberdomide and dexamethasone improved the quality and function of CAR T cells.

Method and Results

Researchers collected blood samples from 24 patients with relapsed/refractory MM and 4 healthy volunteers to assess their results. The first group (n = 7) received iberdomide and dexamethasone along with CAR T-cell therapy "by comparing proliferation, phenotypic makeup, antigen-specific cytokine production, and cytotoxic activity." The second group (n = 17) had previously received CAR T-cell therapy and now took iberdomide and dexamethasone to measure the impact on immune activation using flow cytometry. A third group consisted of the four healthy volunteers to see how iberdomide affected their T cells.¹

Among the first group of patients, the combination of iberdomide and dexamethasone helped the CAR T cells stay active longer and kill more cancer cells. They also found that the ex vivo treatment of healthy T cells with iberdomide "increased the proportion of memory CAR T cells and enhanced CAR T cell expansion and functionality," further strengthening CAR T-cell therapy's efficacy in fighting RRMM.

Researchers found similar promising results in the immune systems of the 17 patients who had previously received CAR T-cell therapy. In this group, patients showed a stronger immune response after iberdomide and dexamethasone treatments; specifically, there was "increased T and NK cell proliferation and shifted T cells from a naive to an activated effector memory phenotype" in this cohort.¹

Memory T cells, as the name suggests, hold a memory of different cells they are sent to target, such as a virus or a cancer. They live longer than other T cells and react faster to the threat and therefore are key to long-term recovery from cancer and other illnesses.

These findings were validated by the results of the 4 healthy volunteers, who also demonstrated a stronger immune reaction through an increase in the number of memory CAR T cells and greater expansion and functionality of CAR T cells overall.

Why This Matters

These results, though early and not statistically meaningful, do show promise in the fight against multiple myeloma and provide justification for further clinical research. The clinical study with these patients is still ongoing, as are several other clinical trials to evaluate the role of iberdomide as a multiple myeloma therapy.

REFERENCES

1. Aleman A, Amatangelo M, Grossman L, et al. Iberdomide (Iber) treatment (Tx) enhances manufactured chimeric antigen receptor (CAR) T cell expansion and functionality and is immunostimulatory in patients post-CAR T cell therapy. Presented at: 22nd International Myeloma Society Annual Meeting; September 17-20, 2025; Toronto, Canada. Abstract PA-307.

2. Bristol‐Myers Squibb. A phase 1/2 randomized study of iberdomide plus dexamethasone in patients with relapsed/refractory multiple myeloma (CC‑220‑MM‑001). ClinicalTrials.gov Identifier: NCT02773030. Updated March 2025. Accessed September 18, 2025. https://clinicaltrials.gov/study/NCT02773030