Image courtesy of NIAID
VALENCIA, SPAIN—Interim results of a phase 1/2 trial suggest the adjunct T-cell therapy BPX-501 can safely accelerate immune recovery after haploidentical hematopoietic stem cell transplant (haplo-HSCT) in pediatric patients with nonmalignant disorders.
Twenty-four such patients received BPX-501 after haplo-HSCT on this trial.
At a median follow-up of 7 months, all 24 were still alive and disease-free.
In addition, the incidence of graft-versus-host disease (GVHD) was considered “very low.”
Pietro Merli, MD, of Bambino Gesù Children’s Hospital in Rome, Italy, presented these results during the Presidential Symposium of the 42nd Annual Meeting of the European Society for Blood and Marrow Transplantation (EBMT) as abstract O007.*
The trial, known as BP-004, was sponsored by Bellicum Pharmaceuticals, the company developing BPX-501.
About BPX-501
BPX-501 consists of genetically modified donor T cells incorporating the CaspaCIDe safety switch, which is designed to eliminate cells in the event of toxicity.
The goal is to allow physicians to more safely perform haplo-HSCTs by giving patients BPX-501 to speed immune reconstitution and provide control over viral infections. But the technology is designed to provide a safety net to eliminate BPX-501 alloreactive T cells if severe GVHD occurs.
The CaspaCIDe switch consists of the CID-binding domain coupled to the signaling domain of caspase-9, an enzyme that is part of the apoptotic pathway. The idea is that, if a patient develops severe GVHD, he can receive an infusion with the small molecule rimiducid. And this will trigger activation of the domain of caspase-9, which leads to selective apoptosis of the CaspaCIDe-containing cells.
About BP-004
In late 2014, Bellicum initiated BP-004, a phase 1/2 trial in children with leukemias, lymphomas, or orphan inherited blood disorders. The trial is being conducted in European and US pediatric transplant centers and is set to enroll up to 90 patients.
At the EBMT meeting, investigators reported results in 41 patients treated on this trial.
Dr Merli presented data on the 24 patients with nonmalignant disorders, including Fanconi anemia (n=5), beta-thalassemia major (n=5), severe combined immunodeficiency (n=5), Wiskott-Aldrich syndrome (n=4), Diamond-Blackfan anemia (n=1), hemophagocytic lymphohistiocytosis (n=1), immune deficiency due to mutation of XIAP gene (n=1), osteopetrosis (n=1), and sickle cell disease (n=1).
All of these patients received a T-cell-depleted haplo-HSCT without post-transplant GVHD prophylaxis.
The patients received BPX-501 within 14 ± 4 days after haplo-HSCT. The phase 1 portion of the trial consisted of a classical 3+3 design, with 3 cohorts receiving escalating doses of BPX-501 cells—2.5 x 105, 5 x 105, and 1 x 106 cells/kg.
In the phase 2 portion, patients received 1 X 106 BPX-501 cells/kg. Rimiducid was only to be used in the event of uncontrollable GVHD.
Results
The median time to platelet recovery was 10 days (range, 7-16), and the median time to neutrophil recovery was 15 days (range, 10-33).
At a median follow-up of 220 days (range, 61-486), there were no reports of transplant-related mortality.
All 24 patients were still alive and disease-free. And none of the patients developed post-transplant lymphoproliferative disorder.
The cumulative incidence of skin-only acute GVHD was 16.6% (n=4), and the cumulative incidence of mild chronic GVHD was 5% (n=1).
This trial also included 17 patients with acute leukemias. Results in these patients were presented at the EBMT meeting as abstract WP16.
*Information in the abstract differs from that presented at the meeting.