EVOMELA® Combination Conditioning Therapy

OVERVIEW:

Elderly and infirm patients with hematological malignancies often cannot undergo allogeneic hematopoietic cell transplantation (HCT) because of high-toxicity rates and nonrelapse mortality (NRM) associated with higher-intensity conditioning allografts.

Reduced-intensity conditioning (RIC) transplantation has emerged as an attractive alternative for these populations.

FLUDARABINE/MELPHALAN. In RIC, fludarabine is often used as the lymphocyte-depleting component to facilitate donor-cell engraftment. This drug can be given once daily because of its plasma half-life. M.D. Anderson pioneered the use of fludarabine melphalan (FLU/MEL) conditioning, which has since gained wide usage. (1) Melphalan is convenient, has broad antitumor activity in hematologic malignancies and has immunosuppressive effects. The Flu/Mel conditioning regimen can provide long-term disease control, especially in the subset of patients with chemo sensitive disease. (1) TOTAL-BODY IRRADIATION. In a recent study, total-body irradiation (200 cGy) was used with flu/mel for advanced lymphoma treated with HCT. With a median follow-up time close to two years, the survival of these mostly advanced, relapsed/refractory patients was very encouraging with overall survival of 54% and progression-free survival of 54% for the entire group. (2) Treatment-related mortality was low at day 100 (9.1%) and two years (19%) after transplantation, with stable engraftment achieved in the great majority of patients.

PROPYLENE GLYCOL-FREE MELPHALAN HCL (EVOMELA®). In theory, intensifying the dose of melphalan in flu/mel conditioning could provide better disease control post HCT, allowing more time for curative graft-versus-leukemia effects to emerge. The use of the commercial formulation of melphalan (Alkeran®) proved somewhat problematic, however, because it must be reconstituted with propylene glycol, a substance that has been associated with toxic side effects. The substitution of Captisol® in propylene glycol-free melphalan HCl (EVOMELA®) for Injection (Spectrum Pharmaceuticals, Inc.) for the excipients found in Alkeran®, directly overcomes the formulation limitations noted with Alkeran®.

STUDY RATIONALE. The preliminary data suggest that the substitution of Captisol® in EVOMELA® for the excipients found in Alkeran® directly overcomes the formulation limitations and provides a potentially safer melphalan formulation for administration at higher doses used in HCT conditioning regimens.

Based on these observations, we now propose a phase II study of a RIC regimen consisting of EVOMELA® in combination with fludarabine and total-body irradiation for patients undergoing haplo-HCT. The study will investigate the safety and tolerability of this conditioning approach. While the FDA indication for EVOMELA® is for myeloablative conditioning prior to autologous HCT in patients with multiple myeloma, we anticipate our study will provide critical preliminary data to explore this formulation in allogeneic HCT conditioning.