Radical Improvement in Prognosis of CNS Ptlds Using Methotrexate Dose Alorithm Regardless of Renal Function
Authors: Choquet Sylvain , Lavaud Anne , Boussen Inès , Roos-Weil Damien , Morel Veronique , Solorzano Silvia , Uzunov Madalina , Leblond Veronique 
Published: November 2021

Abstract
Introduction
While systemic post-transplant lymphoproliferations (PTLDs) have a good prognosis, with a median survival of more than 6 years, PTLD of the central nervous system (CNS-PTLD) have a very poor prognosis with a CR rate of 38% and overall survival (OS) of 43% at 3 years. The main prognostic criterion being the response to the first line (Evens AM et al. Am J Transpl 2013), we hypothesized that the majority of treatment failures were due to the absence or underuse of the major drug in CNS NHL treatment, namely methotrexate (Mtx), due to the high rate of renal failure in transplanted patients.
Patients and methods
Since April 2017, CNS-PTLD treated at Pitie-Salpetriere Hospital, Paris, France, have been systematically treated with a combination of methotrexate on day 1, Cytarabine on days 2 and 3, every 15 days for 6 cures. Cytarabine is given at 2g/m 2/d when the creatinine clearance (cc) is &gt; 50ml/min, 1g/m 2/d below. The dose of Mtx of the first treatment is 100 mg/m 2 in case of dialysis or cc &lt;30 ml/min, between 100 and 500 mg/m 2 for cc between 30 and 50 ml/min, between 500 and 1000mg/m 2 between 50 and 60 ml/min and/or albuminemia &lt;35g /L and/or&gt; 65 years, 3000mg/m 2 in other cases. The dose of Mtx during the following treatments depends on the dosage of Mtx at 24h: below 1 microM the following dose is increased, above 5 microM it is reduced otherwise it remains the same. The results are compared to those of CNS-PTLDs treated in the same unit before April 2017
Results
Of the 182 PTLDs treated since 1990 at Pitie-Salpetriere hospital, 49 are CNS-PTLD, including 16 processed with the new algorithm. The median age is 58 years, 9 patients have kidney or kidney-pancreas transplants, 2 heart, 1 lung and 3 liver, all are EBV positive diffuse large B cell CNS-PTLDs. The diagnosis is made in median 88 months after the transplantation. The cc at the diagnosis is in median of 50 ml / min. Of these 16 patients, only 2 had a cc&gt; 60 ml/min, and only two were able to receive 3000 mg/m 2 of Mtx. The other patients received between 100 and 1000 mg/m 2 at the first treatment, 6 had an increased dose during the next cycles following the algorithm. No worsening of renal function or overdose of Mtx have been rated. Of the 16 patients 14 achieved complete remission (93%), 1 a PR, 1 died of progression after the first cycle, 1 relapsed within 3 months and 1 after 1 year of CR. Median overall survival (OS) is not achieved (448 days +). In comparison, of the 33 CNS-PTLDs treated before April 2017, 10 obtained a CR (30%), 6 a PR and the median OS is 211 days, for the 9 CNS-PTLDs treated without Mtx, only one obtained a CR, 1 a PR and their OS is only 180 days (p=0.016) cf figure
Conclusion
Contrary to general belief, methotrexate can be used regardless of the renal function by adapting its dose to the cc then to the dosages at H24. This new simple algorithm increased the CR rate from 30% to more than 90% and improve OS. In case of confirmation on further series, this new attitude should revolutionize the management of CNS-PTLDs ... but also other CNS-NHLs in case of renal failure
Figure 1 Figure 1.

Disclosures
Leblond: AstraZeneca: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Lilly: Consultancy; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel Support; Roche: Honoraria; Amgen: Honoraria; Beigene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees.