Neutrophil-to-Lymphocyte Ratio as a Biomarker for Clinical Response After Autologous Hematopoietic Stem Cell Transplantation in Systemic Sclerosis

Introduction: Systemic sclerosis is a complex disease that affects various target organs, making it difficult to assess response and determine remission or relapse. A baseline Neutrophil-to-Lymphocyte Ratio (NLR) >2.95 is associated with severe progressive skin and lung disease and decreased 5-year survival in systemic sclerosis (SSc). However, it is unknown whether NLR changes in response to treatment.

Objective: To retrospectively evaluate NLR changes as a biomarker for treatment response in SSc.

Methods: Progressive diffuse SSc patients who were treated with autologous hematopoietic stem cell transplantation (AHSCT group), with combination therapy of rituximab and mycophenolate mofetil (combination group) or CAR-T cell therapy (CAR-T group) were recruited, along with healthy controls (HC group). NLR, modified Rodnan Skin Score (mRSS) and forced vital capacity (FVC)% predicted were repeatedly assessed over 2 years.

Results: Fifteen patients were recruited in the AHSCT group, 15 in the combination group, and six patients in the CAR-T group. Baseline mean NLR was high (>2.95) in AHSCT, combination groups, and CAR-T compared with HC. All treatment arms showed a statistically significant decrease in mRSS values and an increase in FVC% at each time point up to 12 months. In a linear mixed model, NLR significantly decreased up to 24 months only in the AHSCT group. NLR correlated with mRSS and FVC exclusively in the AHSCT group. NLR increased above 3 in two patients who experienced a relapse after AHSCT.

Conclusion: NLR is a simple biomarker that correlated with outcome measures in SSc following AHSCT, but not with conventional therapy or CAR-T therapy. It is suggested that a decrease in NLR following AHSCT may indicate remission, whereas an increase may be associated with exacerbation. Further research is needed to validate these novel findings.