Rituximab and Acalabrutinib in Newly Diagnosed B Cell Post Transplant Lymphoproliferative Disorder

This is a non-randomized phase II study of acalabrutinib plus rituximab in newly diagnosed B-cell PTLD in participants with both solid organ transplant (SOT) and Bone marrow transplant (BMT). Acalabrutinib is an inhibitor of Bruton Tyrosine Kinase (BTK). BTK is important in B cells and plays a role in the development of PTLD. Acalabrutinib is approved in the US for the treatment of adult participants with indolent lymphoma, mantle cell lymphoma, and is being evaluated to treat other lymphomas. Rituximab has been approved for treatment of B cell non-Hodgkin lymphoma (NHL). While not approved for PTLD, it has become the mainstay of treatment. The primary objective of this study is to determine the overall response rate to combination treatment with rituximab and acalabrutinib in patients with PTLD. The secondary objectives of this study is to determine response rates, survival, failure rates, and safety elements in participants with PTLD treated with combination rituximab and acalabrutinib.