Predictive Factors for Transplant Outcomes of Cardiac AL Amyloidosis

Introduction

Light chain amyloidosis (AL) is characterized by the deposition of amyloid fibrils in several organs including the heart, which eventually leads to morbidity and mortality from progressive cardiomyopathy. Patents eligible for high-dose chemotherapy and autologous stem cell transplantation (ASCT) achieve deep and durable responses, however, a subgroup of patients continue to be at higher risk of treatment failure and increased non-relapse mortality (NRM). In this study, we aimed to assess the predictive factors that impact the outcomes of cardiac AL patients after ASCT.

Methods

All consecutive patients with cardiac AL who underwent ASCT between 09/2005 and 11/2021 were included. Primary endpoints were progression-free survival (PFS) and overall survival (OS). Secondary endpoints included the cumulative incidence of NRM.

Results

Of 179 total patients who underwent ASCT during the study period, 88 (59 males, 29 females) patients, with a median age of 61 (range, 27-77) years, were identified to have cardiac AL. Of these, only 10 (11%) had isolated cardiac AL, 44 (50%) patients had 2 organs involved (cardiac + a second organ), and 34 (39%) patients had >2 organs involved. The kidney was the most frequent second organ involved (63%). Overall, 65% of patients had a baseline involved minus uninvolved free light chain (dFLC) level of >180, 62% had Mayo Stage III/IV, and 81% had increased bone marrow plasma cells ≥10%. Twenty-four (29%) patients had KPS at transplant ≥90 and 49 (56%) had HCT-Comorbidity Index (CI) ≤3. Bortezomib, cyclophosphamide and dexamethasone (VCD) was the most frequently induction therapy (48%), followed by proteasome inhibitors +/- immunomodulatory drugs (27%).

With a median follow up of 3.99 (range, 0.27-11.55) years, the 4-year PFS and OS for all 179 AL patients were 56% and 76%, respectively, and the 4-year PFS and OS rates for the 88 patients with cardiac AL were 56% and 67%. The 1- and 4-year cumulative incidence of NRM for patients with cardiac involvement were 6% and 16%, respectively. In MVA for PFS, age ³60 years (hazard ratio (HR) 2.647, 95% confidence interval (CI): 1.171-5.982; p=0.0193) and dFLC ³180 (HR 2.888, 95% CI: 1.101-7.575; p= 0.0311) were associated with worse outcomes. For OS, age ³60 (HR 5.705, 95% CI: 1.874-17.366; p=0.0022), Revised Mayo Stage III/IV (HR 7.017, 95% CI: 2.19-22.488, p=0.001) and HCT-CI >3 (HR 4.448, 95% CI: 1.6-12.361; p= 0.0042) were associated with worse survival. In a subgroup analysis stratifying patients by Revised Mayo Staging, patients with Mayo Stage I/II had a significantly superior 4-year PFS/OS of 75%/91% vs 46%/52% for those with Mayo Stage III/IV (p=0.0149 for PFS; p=0.0012 for OS). For the 10 patients with isolated cardiac AL (n=10), the outcomes were not significantly different from those with cardiac + other organ involvement.

Conclusions

Patients with cardiac AL who underwent ASCT have comparable outcomes to those without cardiac involvement. Among factors that may predict the outcome, Mayo cardiac stage seems to have the strongest impact. Cardiac AL patients with Mayo Stage I/II had an excellent 4-year OS of >90%. Older patients with advanced Mayo Stage and high HCT-CI are at a high-risk for treatment failure or death and may benefit from non- transplant options.