Role of Second Stem Cell Transplant in Patients with Amyloidosis Who Are Refractory or Relapsing.

Introduction: Stem cell transplant is an increasingly widely applied technique for managing amyloidosis. As in multiple myeloma, the treatment would not be expected to be curative and patients would be expected to relapse in most instances. In addition, approximately one-third of patients fail to respond to initial therapy. The role of second transplantation in treatment failures or patients who relapse is reviewed.

Patients: Of 242 patients undergoing high dose conditioning and stem cell transplantation for amyloidosis (AL) at the Mayo Clinic, 6 subsequently underwent a second transplant.

Results: Patient 1, who had single organ renal amyloid nephrotic syndrome responded and relapsed at 73 months, received a second stem cell transplant achieving a hematologic complete response with normalization of a markedly elevated pre transplant free light chain (59 to 1.9 mg/dL) and is alive at 12 months. Patient 2 relapsed 42 months after transplant for single organ renal amyloidosis; the second stem cell transplant, has normalized his free light chain ratio reduced his urinary protein loss from 5450 to 1482 mg/day and he is alive 21 months following his second transplant (63 months overall). Patient 3 relapsed 34 months after a response of renal and cardiac amyloidosis. After transplant two, he failed to achieve a 50% reduction in his free light chain, began hemodialysis 7 months post transplant and died one year post transplant. Patient 4 with single organ cardiac involvement relapsed 30 months following his first transplant and died on day +5 of his second transplant of an acute pulmonary embolus. Patient 5 was a response failure after his first transplant, had a second transplant 35 months later, having failed Dexamethasone followed by Melphalan/Dexamethasone therapy, and died 3 months later of progressive disease. Patient 6 had single organ vascular involvement manifest by calf and thigh claudication and failed to respond with his first transplant with a persistently elevated free light chain. The second transplant was performed six months after the first without further free light chain reduction and persistent claudication at 11 months.

Conclusion: Patients who failed to achieve a hematologic response after a first transplant appear not to benefit from a second course of high dose therapy. Among 4 patients who were previously responsive and relapsed, one achieved a hematologic complete response, one achieved a hematologic partial response, and two died. The two patients achieving a second hematologic response had the longest response duration (73 and 42 months) following their first transplant, and the second response presumably reflects favorable (indolent; non proliferative) biology of the underlying plasma cell dyscrasia. High dose therapy and stem cell transplant may be an effective salvage regimen for patients who responded to a first transplant and whose response lasted greater than 36 months.