TREATMENT AND OUTCOMES OF PATIENTS WITH POST‐TRANSPLANT LYMPHOPROLIFERATIVE DISORDER: A SINGLE CENTRE EXPERIENCE

Abstract

Background: Post-transplant lymphoproliferative disorder (PTLD) is a potentially severe complication that takes place after solid (SOT) or allogeneic hematopoietic stem cell transplant (HSCT). To date, its treatment is not standardised, and choice of therapy depends on histology and clinical presentation. We report the results of a 10 years (yrs) single-centre retrospective study assessing presentation, treatment patterns and outcomes of patients with PTLD. Methods: Patients ≥18 yrs diagnosed with a PTLD between 2011 and 2020 were identified in our medical records database. Primary endpoints were 2 yrs progression-free survival (PFS), overall survival (OS), and relapse incidence (RI) estimated with Kaplan-Meier and comparison between HSCT and SOT group. Secondary endpoints were the overall response rate (ORR) and complete response rate (CRR) at the end of first line treatment. Exploratory univariate analysis for OS, PFS were investigated using Cox regression model. Results: A total of 38 patients were included. Patient's characteristics and treatment strategies are presented in Table 1. HCST patients present a significantly higher prevalence of early onset PTLD (90% in HCST group vs 0% in SOT group), positive EBER immunostaining (100% vs 22%) and detectable Epstein Bar Virus (EBV) viremia (100% vs 28%), higher LDH (95% vs 66%), IPI score 3-5 (50% vs 33%), with a remarkable higher use of single agent Rituximab as first line therapy in HSCT patients (65% vs 11%). 2 yrs PFS was 54% (95%CI 36-73%) for the entire cohort, 42% (95%CI 16-67%) for HSCT and 67% (95%CI 41-92) for SOT; p-value 0.23. 2 yrs OS was 53% (95%CI 41-66%) for the entire cohort, 42% (95% CI 16-67%) for HSCT and 65% (95% CI 39-91) for SOT; p-value 0.22. 2 yrs RI was 9% (95% CI: 0-21%) for the entire cohort, 0% for HSCT and 14% (95% CI 0-33%) for SOT; p-value 0.26. ORR and CRR were similar with 82% (75% for HSCT, 89% for SOT, p-value 0.41) at the end of first line treatment. High IPI score (3-5) demonstrated worse outcome for PFS (HR: 2.5, 95%CI 0.95-6.65, p-value 0.063) and OS (HR: 2.4, 95%CI 0.92-6.48, p-value 0.07). A total of 17 patients died during follow-up: 7 during first line treatment of PTLD complication and multiorgan failure (5 in the HSCT group, 2 in the SOT group; p-value 0.41); 2 following PTLD relapse after first CR (0 in the HSCT group, 2 in the SOT group; p-value 0.22). Conclusion: This study highlights the clinical and therapeutic heterogeneity of PTLD. We observe a worse 2 yrs PFS and OS in patients with high IPI score. CRR after first line treatment is almost 90% in the SOT group, with a 2 yrs OS of 53%, consistent with previous studies (Trappe et al, JCO 2017). The higher mortality observed in the HSCT group suggests that serious treatment-related toxicities remain main challenges in this fragile patient population. New tools to guide therapeutic approaches in PTLD patients are warranted. Keywords: Lymphoid Cancers - Other No conflicts of interests pertinent to the abstract.