Does ibrutinib pre-treatment affect the outcomes of alloHCT for patients with CLL?

This study investigated the safety and effectiveness of alloHCT (allogeneic hematopoietic stem cell transplantation) in patients with chronic lymphocytic leukemia (CLL) pre-treated with ibrutinib (Imbruvica). This study concluded that ibrutinib does not affect the safety of alloHCT.

Ibrutinib has become the standard of care for patients with relapsed or refractory (did not respond to treatment) CLL. This treatment, however, does not cure CLL. Many patients progress despite treatment. Patients who progress generally undergo alloHCT (stem cell transplant using donor stem cells). Whether pre-transplant ibrutinib affects the safety or effectiveness of alloHCT in CLL remains under investigation.

This study included information on 70 patients with mantle cell lymphoma (MCL; 31.4%) or CLL (68.5%). All patients received ibrutinib treatment before alloHCT. The average follow-up period was 12 months.

At the time of transplant, 73% of patients responded to ibrutinib treatment. 10% of CLL patients achieved a complete response (CR; complete disappearance of all signs of cancer). 17% of CLL patients experienced progressive disease.

98.6% of patients had successful engraftment (transplanted stem cells enter the bone marrow and start making new blood cells). 47.1% of patients had grade 2 – 4 acute GVHD (when transplanted cells attack healthy cells). At follow-up, 54% of patients had chronic GVHD. Of these, 23% experienced complete symptom resolution.

After 12 months, the overall survival (time from transplant to death from any cause) was 72% for CLL patients. 60% of patients were progression-free. 30% of patients relapsed. The non-relapse mortality (time from transplant to death not due to relapse or progression) rate was 10%.

This study concluded that ibrutinib does not affect the safety of alloHCT, but relapse rates in CLL were relatively high.

This study was retrospective, meaning it looked back in time to analyze data. As a result, collected data may be incomplete. Also, the patient population was small, and the follow-up period was short. These factors may limit the conclusions that can be drawn from these results. Larger studies are needed to further confirm these results.