POST-TRANSPLANT LYMPHOPROLIFERATIVE DISORDER (PTLD) AFTER SOLID ORGAN TRANSPLANT (SOT): SURVIVAL AND PROGNOSTICATION AMONG 570 PATIENTS (PTS) TREATED IN THE MODERN ERA

Background: PTLDs are rare, aggressive and clinically heterogeneous diseases that may arise in the setting of immunosuppression following SOT. There remains an absence of a standard frontline treatment approach in the real world setting. We conducted a comprehensive multicenter retrospective study to analyze disease characteristics and outcomes of post-SOT PTLD in the modern era. Methods: Data on newly diagnosed pts age ≥18 years (yrs) with SOT-related PTLD from 2000-2017 were analyzed from 10 academic institutions under IRB approval. Detailed patient and disease characteristics were summarized. Survival endpoints estimated by Kaplan-Meier method and compared by log rank test. Results: We identified 570 PTLD pts with median age of 54 yrs (range, 18-82 yrs) at diagnosis. The majority of pts were male (67%), caucasian (79%), and had stage III-IV disease (67%) at diagnosis. Median time from SOT to PTLD was 61 months (range 0.23-1318). SOT type was renal (35%), liver (19%), lung (18%), heart (13%), intestine & pancreas (1% each), other/missing (1%) and 66 pts (12%) had multiple SOT (11% having 2 organs transplanted, 1% 3 organs). 53% had EBV positive tumor. A minority had graft involvement or rejection (19% each) at the time of diagnosis. For therapy, most pts (85%) underwent reduction in immunosuppression (RIS). For 1st line treatment, rituximab (R)-based therapy was given in 65% (R monotherapy 35% and R+chemotherapy 30%); 8% received chemotherapy without R and 27% received RIS alone. Response to 1st line therapy was: complete response (CR) 59% and partial response (PR) 12% yielding an overall response rate of 71% with 8% stable disease and 21% of pts had primary refractory disease. With 41-month median follow-up, the estimated 5 yr relapse free survival (RFS) and overall survival (OS) rates for all pts were 65% and 71%, respectively. The median OS and RFS were 185 and 181 months respectively. 23% relapsed after 1st line therapy. Outcomes varied significantly by SOT type, with cardiac and lung pts having the worst 5-yr RFS [95% CI] (49% [34, 71] and 58% [44, 77], respectively; P=0.09) and 5 yr OS [95% CI] (63% [51, 79] and 59% [48, 72], respectively, P< 0.0001. Achievement of CR vs PR to 1st line therapy by month 3 after diagnosis was strongly associated with RFS (5 yr RFS 69% [95% CI 63, 76] vs 44% [95% CI 31, 64], P< 0.0001). Furthermore, CR vs non-CR to 1st line therapy was associated with significantly improved OS (5 yr OS 85% [80, 90] vs 70% [62, 80], respectively, P< 0.0001). Conclusions: These data represent the largest cohort of SOT-related PTLD pts reported to date. Collectively, pts with lung and heart SOT-related PTLD had significantly inferior OS and depth of response to 1st line therapy was a critical determinant for long-term RFS and OS. Our data demonstrates improved outcomes in pts with newly diagnosed PTLD treated in the era of novel agents. Keywords: post-transplant lymphoproliferative disorders (PTLDs); PTLD. Disclosures: Venugopal, P: Consultant Advisory Role: AbbVie and Bayer. Fenske, T: Consultant Advisory Role: Genentech.