Induction with Bortezomib and Dexamethasone (BD) Followed By Risk Adapted High Dose Melphalan and Autologous Stem Cell Transplantation and BD Consolidation in Patients with AL Amyloidosis: A Phase II Feasibility Study

Background: The depth and durability of hematologic response is a critical determinant of outcome in patients (pts) with light chain (AL) amyloidosis. Complete hematologic remissions (CR) following risk-adapted melphalan and stem cell transplant (RA-SCT) in pts with AL amyloidosis is associated with organ improvement and extended overall survival (OS). We have previously shown that using bortezomib and dexamethasone (BD) as consolidation following RA-SCT is associated with deeper hematologic responses and favorable outcomes. We have conducted a prospective phase II trial using BD as induction followed by RA-SCT and BD consolidation to determine the safety and hematologic and organ response rates of this treatment program for newly diagnosed, transplant-eligible pts with AL amyloidosis.

Methods: Untreated pts with AL amyloidosis received 1-3 cycles of BD (B 1.3mg/m2, IV/SC, and D 40mg, IV/PO, days 1, 4, 8, 11). BD was discontinued before 3 cycles in patients who achieved CR. Pts were then assigned melphalan 100, 140 or 200mg/m2 based on age, renal function and cardiac involvement; Starting 3 months following RA-SCT, pts received six cycles of BD (B 1.3mg/m2, IV/SC and D 20mg, IV/PO days 1, 8, 15, 22) every 12 weeks as consolidation. Hematologic responses were assessed using International Society of Amyloidosis criteria (Palladini et al. JCO 2012) and organ responses using updated criteria (Palladini et al. Blood 2014), after induction, 3 months post RA-SCT, and at 12 and 24 months from treatment initiation. Patients with New York Heart Association Class III/IV heart failure, ECOG > 2 or > grade 2 neuropathy were ineligible.

Results: Twenty pts, 70% male, with a median age of 60.1 years with renal (55%), cardiac (65%), liver/GI (15%) or nervous system (15%) involvement received BD induction and 18 patients have been transplanted. Two pts with cardiac disease died during BD induction (10% TRM); 85% of pts are alive with a median follow up of 28 mo. By intent to treat, 60% and 70% of patients achieved at least a very good partial response (>VGPR) following BD induction and RA-SCT, respectively. Overall, 95% of patients achieved hematologic responses (>PR) including 35% CR. Cardiac and renal responses were seen in 75% (N=8) and 60% (N=10) of evaluable pts at 1 year following treatment initiation. Most common grade >3 adverse events included GI (40%), Renal (30%), infectious (10%), and cardiovascular (10%); Grade 2 or higher neuropathy was seen in 40% of pts and warranted discontinuation of BD consolidation in 35% of pts.

Conclusion: In newly diagnosed AL amyloidosis pts, BD induction followed by RA-SCT was safe and rapidly and effectively induced responses resulting in organ improvement. There was 10% TRM during BD induction and no deaths during transplant supporting the notion that early mortality in newly diagnosed AL pts is independent of treatment received. The high incidence of neuropathy may be related to the administration of BD on a twice weekly schedule and rendered some pts ineligible for post-transplant therapy. Whether transplant-eligible pts will ultimately derive more benefit from proteasome inhibitor induction versus consolidation is worthy of further study.