Abstract

Abstract 1937

Background:

Despite the advantages of autologous stem cell transplantation (ASCT) over conventional chemotherapy, the results of ASCT in multiple myeloma (MM) are still unsatisfactory. Intravenous (iv) melphalan at a dose of 200 mg/m2 is the most commonly used conditioning regimen for ASCT. However, better conditioning regimens are still needed, and more intensive conditioning regimens have been investigated. We evaluated the role of bortezomib-containing regimen (escalated dose of bortezomib + iv busulfan and iv melphalan) in the MM patients who had a sensitive response to bortezomib during the induction chemotherapy. In the phase 1 trial, we assessed the MTD (maximum tolerated dose) of bortezomib. The trial is registered on National Cancer Institute website, number NCT01255527.

Methods:

Nine MM patients who were candidate for ASCT enrolled in this study. M:F=5:4 and median age were 59 (34–62). They were treated with escalating doses of bortezomib as a conditioning regimen (N=3/group; 0.7, 1.0, and 1.3 mg/m2 on D-6, D-3 & D+1) and a fixed dose of busulfan (3.2 mg/kg from D-5 to D-3) and melphalan (140 mg/m2 on D-2). Dose limiting toxicities (DLT) were defined as any toxicity of grade 3 or greater, with the following exceptions: vomiting, fatigue, alopecia, libido, amenorrhea, nausea, febrile neutropenia, infection, anorexia, depression, anxiety, and cytopenias. Grade 3/4 hematological toxicity was acceptable. Grade 4 of mucositis, °Ã Grade 3 diarrhea and °Ã Grade 3 cardiac toxicity were regarded as DLT. Only one patients had grade 3 oral mucositis and there were no other non hematologic toxicities of grade 3 or greater. DLT refers only to toxic events (symptomatic grade °Ã 3 toxicity) that occur until day +28 after ASCT and are attributed as possibly, probably, or definitely due to treatment.

Results:

Four patients had grade 3 oral mucositis (2 in 0.7 mg/m2 group, 1 in 1.0 mg/m2 group and 1 in 1.3 mg/m2 group), but no grade 4 (considered as DLT) oral mucositis. No other non hematologic toxicities of grade 3 or greater. Therefore, there were no dose limiting toxicities in this phase 1 trial and MTD of bortezomib was 1.3 mg/m2. Median times to ANC > 0.5 · 106/L and platelet > 20 · 106/L were 12 and 10 days, respectively, with no graft failures. All patients achieved at least very good partial response. Six patients (67%) achieved complete remission(CR) after ASCT.

Conclusion:

In the phase 1 trial, MTD of bortezomib was 1.3 mg/m2. Addition of bortezomib to busulfan and melphalan conditioning regimen shows to be safe, well-tolerated and worthy of phase 2 trial.

Disclosures:

No relevant conflicts of interest to declare.

Author notes

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Asterisk with author names denotes non-ASH members.