Improved Mobilization of CD34+ Peripheral Blood Stem Cells (PBSC) and Dendritic Cells (DCs) by AMD-3100 (AMD) in Hard to Mobilize Non-Hodgkin’s Lymphoma (NHL) Patients (pts) Mobilized with Standard Dose of G-CSF.

PBSC mobilization for auto transplantation of NHL pts with multiple regimens of prior chemotherapy is hard to achieve and 25%–30% of patients experience mobilization failure. AMD is a small bicyclam compound which specifically binds to CXCR4 receptor and blocks signaling through SDF-1. Previous studies in normal donors suggested clear dose dependent CD34+ cell mobilization as a single agent as well as additively with G-CSF with little toxicity (ASH meeting, 2002; 2003). Similarly, previous studies with NHL and Myeloma patients resulted with a dose-dependent augmentation of CD34+ cell mobilization in pts receiving G-CSF with little toxicity. The exact mechanism of AMD-induced mobilization of CD34+ cells was not studied in patients and AMD was not used before for PBSC mobilization in hard to mobilize NHL patients. Furthermore, its effect on mobilization of DCs and lymphoma cells was not studied before. On November 2003, we initiated a phase II study of 10, hard to mobilize NHL patients, receiving 16ug/kg of G-CSF for 4 days and G-CSF followed by 240ug/kg of AMD on day 5, 9 hours before apheresis collection. G-CSF and AMD were continued for additional day or 2, as needed, in order to collect the target dose of ≥ 2x10⁶ PBSC/kg. Ten liters of blood were exchanged in ~4hours of apheresis. Median age was 54 years (44 to 63 years). Of the 10 patients enrolled, 6 pts had diffuse large cell lymphoma and 3 had follicular histology with 8/10 received 2 regimens of chemotherapy, 2 of which received also radiation prior to mobilization. At mobilization, 5/9 pts were primary refractory, 3 pts were in 1^st relapse, 1 pt in 2nd relapse and 1 pt in 2nd CR. We determined percent CD34+ cells and percent DC1 and DC2 cells as well as percent lymphoma cell mobilization (by Real time DNA-PCR) at baseline (before administration of G-CSF) and before and after AMD, in the blood and in the apheresis product. To date 7 pts were transplanted. Five pts collected in 1 day and 5 pts collected in 2 days. No adverse events were observed during mobilization. All patients collected ≥ 2x10⁶ PBSC/kg and 7 pts have been transplanted with a dose of 2-7x10⁶ PBSC/kg. All transplanted pts engrafted with a mean of 10 days (9 to 12 days) for ≥ 500ANC and with a mean of 13 days (12–14 days for 6/7 pts) to reach 20K of plts. One pt had a delayed plt engraftment and was engrafted on day 27. Addition of AMD to G-CSF, prior to the first or 2^nd PBSC collection resulted in a mean increase of percent CD34+ cells from 0.11% to 0.17% ( p=0.017), with a similar mean increase in CD34+ cells/ul (35/ul to 81/ul; p=0.0001) followed by normalization of CD34+ cells/ul within 24 hours. Similarly, addition of AMD to G-CSF resulted in an increase in the mean of DC1 cells from 79/ul to 156/ul (p=0.009) and from a mean of 62/ul to164/ul (p=0.006) for DC2 cells. One pt had 0.08% lymphoma cells at baseline by DNA-PCR for the major breakage point of the Bcl-2 translocation sequence, with no detectable lymphoma cells in the blood or apheresis collection post AMD. All other pts were negative for lymphoma pre and post AMD by this test. Adverse events and sever adverse events related to study were minimal. We conclude that AMD is a safe drug with clinical benefit in increasing PBSC and DC mobilization with no detectable mobilization of lymphoma cells.