Ibrutinib treatment resulted in sustained minimal residual disease (MRD) negativity without the development of graft-vs-host disease (GVHD) in patients with relapsed chronic lymphocytic leukemia (CLL) who had underwent allogeneic hematopoietic stem cell transplantation (HSCT), according to a study published in the journal Blood.1

Ibrutinib is an oral, once-daily, small molecule inhibitor of both Bruton’s tyrosine kinase and interleukin-2 inducible kinase (ITK). It is approved for the treatment of CLL and has been shown to prolong overall and progression-free survival.

To evaluate the benefit of ibrutinib in relapsed CLL following allogeneic HSCT, researchers analyzed data from 27 patients with relapsed CLL who received ibrutinib salvage therapy after allogeneic HSCT. Of those, 16 were participants of multicenter clinical trials and achieved an overall response rate of 87.5%.


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The other 11 patients were treated at Stanford University following the approval of ibrutinib and achieved a complete response rate of 64% and a partial response rate of 27%.

The study also showed that of the 9 patients treated at Stanford who had mixed chimerism-associated CLL relapse, 44% converted to full donor chimerism after the initiation of ibrutinib, corresponding with disease response.

In addition, 36% of patients achieved MRD negativity with CLL in less than 1 per 10,000 white blood cells, which persisted after treatment discontinuation.

No patients developed GVHD following ibrutinib initiation, which could be due to ibrutinib enhancing graft-vs-leukemia benefit through ITK inhibition.

Reference

1. Ryan CE, Sahaf B, Logan AC, et al. Ibrutinib efficacy and tolerability in patients with relapsed chronic lymphocytic leukemia following allogeneic HCT. Blood. 2016 Nov 1. doi: 10.1182/blood-2016-06-715284. [Epub ahead of print]