Venetoclax Shows Activity Against T-ALL in Children

Data from a small retrospective study suggest that venetoclax-based regimens may have activity against relapsed or refractory T-lineage acute lymphoblastic leukemia (T-ALL) in children and young adults.

Among seven patients with T-ALL treated with venetoclax (Venclexta) in combination with chemotherapy, four had complete remissions and one had a CR with incomplete recovery of blood counts (CRi), and all four patients had undetectable minimal residual disease (MRD), reported pediatric hematology/oncology fellow Amber Gibson, MD, and colleagues from the University of Texas MD Anderson Cancer Center Children’s Cancer Hospital in Houston.

“This single-institution retrospective review found that venetoclax was safe and well tolerated in combination chemotherapy regimens, thrombocytopenia and neutropenia were the most common toxicities identified, [and] venetoclax should be considered for patients with refractory T-cell ALL and investigated as up-front therapy for this patient population,” they wrote in the abstract accompanying a poster presentation at the annual meeting of the American Society of Pediatric Hematology/Oncology.

Children with relapsed T-ALL and T-lymphoblastic lymphoma (T-LL) have a dismal prognosis, with a 3-year event-free survival rate less than 10%, according to the researchers.

To see whether venetoclax, an inhibitor of the antiapoptotic protein B-cell lymphoma-2 (BCL-2), could improve outcomes for children with ALL, the investigators conducted a retrospective chart review of the safety and efficacy of venetoclax in young patients with relapsed/refractory ALL/LL who received the drug at their center.

They identified 10 patients aged 6-21 years (median, 18), 5 of whom had T-ALL (1 with early T-cell precursor ALL), 2 with T-LL, and 3 with B-lineage ALL (B-ALL).

The median number of prior lines of therapy was 3.5. Three of the 10 patients had received hematopoietic stem cell transplants, and the 3 patients with B-ALL had all received prior CD19-directed chimeric antigen receptor T-cell (CAR T) therapy. One of these patients received a dual CD19/CD22 CAR T product, one received CD19-directed blinotumumab.

There were no new safety signals with venetoclax, no treatment-related deaths, and no deaths within 30 days of starting venetoclax.

All 10 patients had grade 4 thrombocytopenias, 6 had grade 4 neutropenia, 3 had grade 4 febrile neutropenia, 2 had grade 4 anemia, and 1 each had grade 4 sepsis, pneumonia, or coagulopathy.

As noted, there were three CRs and one CRi, all in patients with T-ALL. All four of these patients were MRD negative by flow cytometry at a median of 22 days. The median duration of response was 17.4 months (range, 2-18 months).

At the most recent follow-up five patients were still alive, three without disease, one was still undergoing treatment, and one was alive following an allogeneic HSCT.

Early Studies

Shilpa Shahani, MD, a pediatric oncologist and assistant clinical professor of pediatrics at City of Hope in Duarte, Calif., who was not involved in the study, said that there are early studies exploring the use of venetoclax in infants with ALL.

“Venetoclax is a BCL-2 inhibitor that is pretty well tolerated, but you can also have cytopenias with it,” she said.

She noted that it is not typically used in the frontline setting in pediatric populations, but may be considered for patients with difficult-to-treat disease or for whom the relatively good toxicity profile might be appropriate.

The MD Anderson investigators did not report a funding source. The authors and Shahani reported no relevant conflicts of interest.

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