Outcome after Second Autologous Stem Cell Transplantation as Salvage Therapy in Patients with Relapsed Multiple Myeloma.

Background: Single autologous stem cell transplant (ASCT) is considered the standard of care for younger multiple myeloma (MM) patients (pts). However, it is not curative and virtually all patients will ultimately relapse. The role of a second ASCT as salvage therapy is unclear.

Method: Retrospective review of all MM pts who received a 2^nd ASCT as salvage therapy at Princess Margaret Hospital.

Results: Between March 1992 and August 2004, 28 MM pts received a second ASCT for relapsed MM at our institution. Median age was 57 years (range 39–69) at second transplant. 17 pts were male.

Immunoglobulin subtype included IgG (16), IgA (8), light chain (1), nonsecretory (2) and IgM(1). Median initial albumin was 42g/l (27–48). In 15 patients in whom cytogenetic studies were available, 2 were positive for the 13q deletion.

Transplant conditioning regimen for first transplant was melphalan (MEL) + TBI +/− etoposide (E) in 6, MEL alone in 15 and other regimens in 7 pts. 2^nd ASCT conditioning consisted of MEL + TBI +/− E in 2, MEL alone in 25 and BU+CY in 1. Median CD34 counts were 10.96x10⁶/L and 4.85x10⁶/L for 1^st and 2^nd ASCT respectively.

The median time from diagnosis to first transplant was 9 months (2–74). The median time to relapse after the first transplant was 29 months (6–85), with a median interval between transplants of 39 months (6–99). The median time to progression after the second transplant was 13 months (5–56).

No transplant-related deaths occurred.

At median follow-up after 2^nd ASCT of 15 months (1–60), 20 (71%) pts are alive. Twelve pts (43% of all pts) are free of disease progression. The 5-year actuarial progression-free survival (PFS) and overall survival (OS) was 47% and 32%, respectively. Long term progression-free status based on the progression-free interval after 1^st transplant is summarized in the following table:

Conclusions:

1. 2^nd ASCT is a feasible and safe salvage therapy in relapsed MM patients;

2. 2^nd ASCT is effective in providing prolonged remission over one year;

3. 2nd ASCT is most effective in patients whose time to progression after 1st ASCT exceeds 24 months.