The European Commission has granted orphan drug designation for the T-cell therapy product candidate BPX-501 and the small molecule rimiducid.
BPX-501 consists of genetically modified donor T cells incorporating the CaspaCIDe safety switch, which is designed to eliminate the T cells in the event of toxicity.
Rimiducid is used to activate the CaspaCIDe safety switch, which consists of the CID-binding domain coupled to the signaling domain of caspase-9, an enzyme that is part of the apoptotic pathway.
The goal of this therapy is to allow physicians to more safely perform haploidentical hematopoietic stem cell transplant (haplo-HSCT).
Haplo-HSCT recipients receive BPX-501 to speed immune reconstitution and provide control over viral infections. And rimiducid is used to eliminate BPX-501 alloreactive T cells if severe graft-vs-host disease (GVHD) occurs.
If a patient develops severe GVHD, rimiducid is used to trigger activation of the domain of caspase-9, which leads to selective apoptosis of the CaspaCIDe-containing cells.
About orphan designation
Orphan drug designation from the European Commission provides regulatory and financial incentives for companies to develop and market therapies that treat serious or life-threatening conditions that affect no more than 5 in 10,000 people in the European Union (EU), and where no treatment is currently approved.
In addition to a 10-year period of marketing exclusivity in the EU upon product approval, orphan drug designation provides fee waivers, protocol assistance, and marketing authorization under the centralized procedure granting approval in all EU countries.
BPX-501/rimiducid development
BPX-501 and rimiducid are being developed by Bellicum Pharmaceuticals.
The company has met with regulatory authorities in Europe to discuss the potential approval pathway for BPX-501 and rimiducid for the treatment of immunodeficiency and GVHD following haplo-HSCT in pediatric patients with leukemias, lymphomas, and rare inherited blood diseases who do not have a matched donor.
These discussions have resulted in an initial agreement regarding the company’s development plans, subject to further refinement in a formal protocol assistance process that is available for orphan drug products.
Based on regulatory discussions, Bellicum believes that data from the European arm of its BP-004 trial, with a 6-month follow-up time and expanded to enroll additional patients, could form the basis of marketing authorization applications for BPX-501 and rimiducid.
The European Medicines Agency’s Committee for Medicinal Products for Human Use has agreed that review and approval under “exceptional circumstances” may be suitable, recognizing that a randomized trial may not be feasible in the pediatric setting. In place of a randomized trial, Bellicum intends to collect data from a concurrent observational study of allogeneic HSCT outcomes in the pediatric setting.
The European Medicines Agency can grant early market authorization to orphan drug products under exceptional circumstances. Exceptional circumstances can be granted for medicines that treat very rare diseases or where controlled studies are impractical or not consistent with accepted principles of medical ethics.
BP-004 trial
BP-004 is a phase 1/2 dose-escalation trial of BPX-501 and rimiducid in pediatric patients with malignant and nonmalignant diseases. Interim results from this trial were reported in 2 presentations at the 42nd Annual Meeting of the European Society for Blood and Marrow Transplantation in April 2016.
One presentation involved patients with acute leukemia who received BPX-501 after haplo-HSCT. At a median follow-up of 7 months, 16 of the 17 patients were alive and disease-free. There were several cases of GVHD, but nearly all were resolved.
The other presentation covered patients with nonmalignant disorders who received BPX-501 after haplo-HSCT. At a median follow-up of 7 months, all 24 patients studied were still alive and disease-free. The incidence of GVHD was considered “very low.”
