Flomenberg, Neal

Abstract CXCR4, the chemokine receptor for stromal derived factor-1 (SDF-1) plays an important role in the homing and migration of hematopoietic stem cells. Selective inhibition of the binding of the CXCR4 receptor by the molecule AMD3100 leads to the mobilization of hematopoietic progenitors, including CD34+ cells into the circulation, even in the steady state. Preliminary studies have indicated that AMD3100 given 10–11 hours before each apheresis along with standard doses of G-CSF mobilizes more CD34+ cells per kilogram than does G-CSF alone. A Phase II study of this combination in patients with NHL and myeloma is underway. G-CSF at 10μg/kg/day for a duration of up to 9 days is administered with AMD3100 at 240 μg/kg/day starting on the evening of day 4 of G-CSF therapy, (10–11 hours prior to first and subsequent daily aphereses) until 5 x 106 CD34/kg are collected, or for a maximum of 5 days of a standard 3 blood volume apheresis. Both agents are administered subcutaneously. To date 20 patients (myeloma-6, NHL-14) have been enrolled and analyzed. Of these 20, 14 are considered to have been ‘heavily pre-treated’ using standard definitions (≥ 10 cycles of chemotherapy, platinum based salvage chemotherapy and/or radiation therapy to bone marrow sites). Blood CD34 assays (cells/μl) were performed before and after each AMD 3100 dose and on each apheresis product. After the first dose of AMD3100 there was a 2.6 fold increase in CD34/μl in blood (23 → 60 CD34+ cells/μl). The median number of apheresis performed was 2 (range 1–5); the median total CD34 collected for all 20 patients was 5.7 x 106/kg (range 2.32–14.58 x 106/kg). All patients had collections of > 2.0 x106 CD34/kg, and in 12 of 20 the 5 x 106 CD34/kg cell dose goal was collected, including 8 of 14 in the heavily pre-treated group. In fact in 6, the 5 x 106 CD34/kg cell dose was collected in a single apheresis. The median CD34/kg cell dose collected for the 14 heavily pre-treated patients was 5.7 x 106/kg (2.32–6.48 x 106/kg). There were no serious AE’s related to the use of AMD3100. Transient GI toxicity (mostly diarrhea) occurred in 10 of 20 patients shortly after the injections of AMD3100, but only 3 required therapy. Engraftment data is available for the first 12 patients treated. Time to ANC >500/μl and platelets > 20,000/μl was 9 (range 8–10) and 12 (range 9–19) days respectively. This novel combination of AMD3100 and G-CSF appears to be effective in mobilizing large numbers of CD34+ cells, even in patients considered to be heavily pre-treated, and is an effective alternative to chemotherapy/cytokine mobilization. Compared to studies of G-CSF alone, this combination may reduce the number of apheresis procedures needed to collect an adequate graft for rapid hematopoietic engraftment. The study is ongoing with accrual to date of 40 patients.

Abstract Background: Conventional AlloTx for MM is associated with TRM exceeding 20%. Non-myeloablative AlloTx (NST) utilizes the known graft-vs-myeloma (GVM) effect in an attempt to eradicate minimal residual disease. Preliminary studies of NST in MM demonstrated significant CR and low 100 day post-NST TRM (Badros et al Blood97:2574, 2001). However, even though response rates were high, the vast majority of pts with significant MM disease at the time of transplant, relapsed within the first year. To provide maximal tumor cytoreduction to allow for a subsequent GVM effect, the ECOG designed a Phase II trial of AHSCT for maximal tumor cytoreduction followed by a matched sibling NST to allow for a GVM effect. Methods: The study was designed as a two-stage process based upon early transplant mortality in the first 100 days. Eligibility included pts treated as part of induction therapy or salvage therapy. Chemotherapy responsive disease was not required. Only matched sibling donors were allowed. Pts must have had adequate PS and physiologic organ function. After stem cell mobilization, pts received melphalan 200 mg/m2 with AHSCT. Pts underwent NST 100–182 d post-AHSCT following fludarabine 30 mg/m2 daily × 5 and cyclophosphamide 1 g/m2 for 2 days. GVHD prophylaxis included cyclosporine and corticosteroids. For pts with acute GVHD, Zenapax 1 mg/kg for 5 doses q 3 d was recommended. GM-CSF was incorporated post-AHSCT and NST. The primary endpoints were day 100 TRM, early graft failure, extent of acute GVHD, toxicities, DFS and OS. The study was suspended for 6 mo after the first 19 pts to evaluate early TRM-no early TRM was observed and the study was re-opened. Results: From 5/3/01 to 1/14/05, 32 pts from 10 institutions were enrolled on the study. 23 patients, median age 51 (range 32–64) completed both transplants (28% drop-out rate): 7 (30%) CR (2 in CCR), 11 (48%) PR and 2 (9%) NR and 3 (13%) NE as the best overall response. Of the 32 pts who completed AHSCT, there were 12 grade 4 toxicities pre-NST; 11/23 pts had grade 4 toxicities post-NST. Acute grade III/IV GVHD was observed in 4 (17%); chronic GVHD was observed in 9 pts (39%): 5 limited; 4 extensive resulting in 3 CR (33%), 1 CCR, and 3 PR (33%). 1 pt (4%) had graft-failure. Two pts (8.7%; 95% CI 1.6%, 24.9%) had TRM prior to day + 100 post-NST. With a median follow up of 3.5 years from registration, the median PFS was 4.4 years and the 2-year survival rate was 78% (95% CI: 61% ∼ 95%) for the 23 pts who completed both transplants. Conclusions: AHSCT followed by NST is feasible in a Cooperative Group setting with a low early TRM. The PFS and OS were superior to historical reports for single and tandem AHSCT. AHSCT-NST tandem transplants resulted in a 78% overall response, including 30% CR (2/7 CCR) - similar to other reports for AHSCT-NST. 3/9 pts with chronic GVHD achieved CR demonstrating the GVM effect. However, a plateau in PFS or OS was not observed indicating that the GVM effect is not sufficient to produce long- term disease control and is unlikely curative using this treatment schema. Future studies should include novel therapies to induce better responses pre-transplant and consideration for post-NST maintenance to further eradicate MRD while allowing for GVM.