Background:

Chimeric Antigen Receptor T-cell (CART) therapy has become an important approach for treating acute B-lymphoblastic leukemia (B-ALL) that relapses after hematopoietic stem cell transplantation (HSCT). Radiotherapy may aid in treating leukemia with extramedullary infiltration. Combining CART with radiotherapy might enhance the treatment of extramedullary relapse of B-ALL post-transplant.

Objective:

To investigate whether CART combined with radiotherapy can improve outcomes in treating extramedullary relapse of B-ALL post-transplant.

Methods:

This study included 15 cases of extramedullary relapse of B-ALL post-HSCT treated at Beijing Boren Hospital from August 2017 to October 2023. The median age was 31.5 years (range: 12-71 years), with 7 males (46.7%) and 8 females (53.3%). Nine patients (60%) had concurrent bone marrow relapse before treatment. All patients received CART combined with local radiotherapy targeting sites of extramedullary infiltration. The follow-up period ended on July 1, 2024, with a median follow-up duration of 413 days. Progression-free survival (PFS) and overall survival (OS) were the primary endpoints.

Results:

Among the 15 patients treated with CART combined with local radiotherapy, 11 achieved complete remission in both bone marrow and extramedullary sites, yielding a remission rate of 73.3%. By the end of the follow-up period, 6 patients (54.5%) had relapsed, while 5 remained in continuous remission (45.5%). The median PFS of 1428 days. The 1-year PFS rate is 62.3%, and the 2-year PFS rate is 51.9%. The median OS not yet reached. The 1-year OS rate is 100.0%, and the 2-year OS rate is 83.3%.

Conclusions:

CART is an effective treatment method for post-transplant relapsed acute B-lymphoblastic leukemia.

Combining CART with radiotherapy may help improve the remission rates for post-transplant extramedullary relapsed acute B-lymphoblastic leukemia.

Disclosures

No relevant conflicts of interest to declare.

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