Autologous Stem Cell Transplantation in Patients with Autonomic Neuropathy Due to AL Amyloidosis

Aim: The autonomic nervous system plays an essential role in homeostasis and the response to stress. The peri-transplant period can be a challenging time for homeostatic responses due to the fluid shifts, sepsis and cardiac dysrhythmias that can occur. Patients with AL amyloidosis may have significant autonomic neuropathy (AN) that renders the peri-transplant care problematic. The purpose of this study was to compare a cohort of patients with AL amyloidosis complicated by AN with a matched cohort without AN to determine the outcome of patients with AN during and after stem cell transplantation (PBSCT).

Methods: We performed a nested case-control study by searching the Mayo Clinic dysproteinemia transplant database for all patients with AL amyloidosis who underwent autologous PBSCT. Patients with proven AN were identified and compared to a large cohort of matched controls. We have complete follow-up on all the patients. The main outcome variables were overall survival (OS), the duration of hospitalization, incidence of sepsis, peri-transplant atrial fibrillation (AF) and engraftment kinetics. Comparisons between groups were performed with the Mann Whitney U test for continuous variables and the chi squared test for nominal variables. Overall survival was determined by the Kaplan-Meier method. A stepwise Cox proportional hazards model was used to evaluate the impact of various parameters on OS.

Results: We identified 13 patients with AN who underwent PBSCT and compared them to a control group of 94 patients. The two cohorts were well matched for many of the relevant clinical and laboratory characteristics prior to PBSCT. Notable differences included (i) patients with AN tended to have more organs involved (2.5 versus 1, p<0.001) and as a result (ii) the conditioning dose of melphalan was often reduced (p=0.0015). There was no difference in the number of apheresis sessions required for CD34+ cell collection (2.5 versus 2.0, p=0.99), or the number of CD34+ cell collected (6.75 versus 8.15 x10⁶/kg, p=0.99) between the two cohorts. The median hospital duration was 10 (1 – 78) and 8 (0 – 78) days (p=0.99) respectively. Engraftment kinetics, as measured by the time to reach a neutrophil count > 500/ml (p=0.85), a platelet count > 20,000/ml (p=0.99) and a platelet count > 50,000/ml (p=0.99) were similar in the two cohorts. Culture positive sepsis was more common in patients with AN (75% versus 47%, p=0.014). Atrial fibrillation occurred in all patients with AN but in only 1 patient from the control group (p<0.0001). The median OS from PBSCT was 45.2 months for all the combined groups. However, the median OS for patients with AN was 29 months but not yet reached for the controls (p<0.0001). On univariate analysis, cardiac involvement (p=0.0132), AN (p=0.0011), GFR (p=0.038), number of organs involved (p=0.0064) and NT-pro-BNP (p=0.039) all had an impact on OS. On multivariate analysis, AN remained an independent adverse determinant of OS.

Conclusion: Patients with autonomic neuropathy secondary to AL amyloidosis can undergo PBSCT safely with similar engraftment kinetics. They are at a higher risk of peri-transplant atrial fibrillation and sepsis although their hospitalizations are not longer compared to controls. Patients with AN generally have more organ involvement by AL amyloidosis. However, AN is an independent, adverse determinant of OS in AL amyloidosis.