Long Term Follow-Up of 4-Hydroperoxycyclophosphamide Purged Autologous Bone Marrow Transplantation in Non-Hodgkin’s Lymphoma Patients with High Risk of Bone Marrow Involvement.

Introduction: High-dose chemotherapy and autologous stem cell transplant (ASCT) can result in long term survival for patients with advanced non-Hodgkin’s lymphoma (NHL) but relapse remains a common cause of treatment failure. Bone marrow (BM) involvement is common in NHL and there is controversy over whether or not reinfusion of BM stem cells contaminated by clonogenic tumor cells is a major cause of relapse following ASCT. Bone marrow purging can reduce the number of tumor cells in vitro, but the impact on relapse and disease free survival (DFS) remains unknown.

Methods: Between 1990 and 1993, 20 pts with poor prognosis NHL (B-symptoms, high LDH, bulky adenopathy, stage III or IV, or relapsed disease) at high risk for BM involvement underwent 4-hydroperoxycyclophosphamide (4-hc) purged BM transplantation. Thirteen pts had low grade B-cell NHL, 6 had an intermediate grade B-cell NHL with a small B-cell component, and 1 had T-lymphoblastic lymphoma. Seven of 20 pts had received ≥3 prior chemotherapeutic regimens. Three pts underwent transplantation in first complete remission and 17 pts were in chemotherapy-responsive relapse. At diagnosis, 11 of 20 pts had documented BM involvement, and at ASCT, 6 of 20 pts had BM involvement (all < 5% involvement at BM harvest). Eighteen pts (90%) received 4-hc purged autologous BM, and 2 pts (10%) received 4-hc purged autologous BM and peripheral stem cell support. High dose regimens included Cytoxan/TBI (85%), BCV(10%), and Melphalan/TBI (5%). The median age was 45 yrs (range: 20–57 yrs). The median nucleated cell count of 4-hc marrow that was reinfused was 2.4 × 10⁸ /kg (range: 0.87–5.5). The median time to granulocyte recovery was 26 days (range: 14–59). Two pts died at days 31 and 35 without achieving platelet transfusion independence. In the remaining 18 pts, the last platelet transfusion was given at a median of 29 days post-marrow infusion (range 18–149), and the median in-patient hospital days was 27 (range: 16–82 days).

Results: There were 2 deaths (fungal infection and CNS relapse) during ASCT. One pt died in CR after developing secondary AML 5.34 yrs after ASCT. Post-ASCT, 18 of 20 pts achieved CR (including 1 pt who had no evidence of disease at autopsy), 1 pt had a PR, and 1 pt died during BMT and was not evaluable for response. Median follow-up for the group was 8.2 yrs (range: 0.1–12.4 yrs). At last follow-up, 9 pts remain in CR (1 died of AML in CR), 5 pts had relapsed and remain alive, and 5 pts died of progressive disease. Median follow-up for survivors was 11.1 yrs (range: 5.2–12.4 yrs). 65% of pts remain alive at last follow-up. The median EFS was 9.4 yrs (range: 0.1–12.4 yrs). Those who achieved a CR post-ASCT had a median DFS of 10.6 yrs (range: 1.1–12.4 yrs). At 8.2 yrs, 4/6 pts with involved BM at the time of harvest had relapsed or died compared to 7/14 pts with negative BM which is not significantly different.

Conclusion: ASCT using 4-hc BM purging is feasible and can result in long term relapse free survival, even for pts with subtypes of NHL at high risk for BM involvement. Whether 4-hc BM purging is equivalent or superior to immunologic approaches to stem cell processing remains to be determined.