Long‐Term Outcomes of Reduced Intensity Conditioning Hematopoietic Stem Cell Transplantation for Systemic Sclerosis Patients with Impaired Cardiac Function

Objective High intensity conditioning autologous hematopoietic stem cell transplantation (AHSCT) is standard of care for patients with advanced SSc. The role of reduced intensity conditioning (RIC) prior to AHSCT in this population remains unclear. We conducted this study to determine the long‐term outcomes of RIC AHSCT in SSc patients with cardiac involvement. Methods We evaluated 42 participants who sequentially underwent RIC AHSCT five years after the last participant was treated. Progression was defined as reinitiation of DMARDs or worsening end‐organ failure. We determined overall survival (OS) and progression‐free survival (PFS) by the Kaplan‐Meier method and identified pre‐transplant characteristics associated with OS or PFS by multivariable Cox regression. Results All participants had evidence of SSc with cardiac involvement. 95% of participants had interstitial lung disease. The median percent predicted forced vital capacity and diffusing capacity of the lungs for carbon monoxide was 62% and 45%, respectively. The five‐year OS was 75% (95% confidence interval [CI]: 63‐90%), and five‐year PFS was 59% (95% CI: 46‐76%). Pre‐transplant supplemental oxygen use (HR: 7.88, p<.01) and elevated B‐type natriuretic peptide (BNP [HR: 1.005 per pg/mL, p<.01]) was associated with mortality. Anti‐Scl‐70 antibody positivity (HR: 3.03, p=.02) was associated with progression. 24 participants (57%) who did not use supplemental oxygen and had BNP < 100 pg/mL pre‐transplant had a five‐year OS of 91% (95% CI: 80‐100%). Conclusion RIC AHSCT is safe for patients with severe manifestations from SSc. Supplemental oxygen use, elevated BNP, and anti‐Scl‐70 antibody positivity were risk factors for worse outcomes after RIC AHSCT.