Intrathecal (IT) Chemotherapy for Central Nervous System (CNS) Prophylaxis in Diffuse Large B-Cell Lymphoma (DLBCL): A Single Centre Retrospective Observational Study
Authors: Attwell Luke , Gray Benjamin , Hall Rachel , Killick Sally , McCarthy Helen , Walewska Renata , Chacko Joseph M. 
Published: November 2020

Introduction:
CNS relapse of DLBCL is associated with poor prognosis. Estimated incidence varies between 1.9 and 8.4%1. The CNS-International prognostic index (IPI)2 help risk stratify and estimate the 2-year risk of CNS relapse in DLBCL patients treated with R-CHOP chemotherapy. CNS prophylaxis is indicated in patients with a high risk of CNS relapse (a score of ≥4 equated to a 10.2% risk). High-risk DLBCL patients outside the CNS-IPI system include double/triple-hit (MYC/BCL-2/BCL-6 translocations) lymphoma, HIV lymphoma, testicular lymphoma, primary cutaneous lymphoma-leg type, stage IE breast lymphoma3. IT methotrexate or cytarabine administered during the course of systemic chemotherapy has been the most widely employed method of CNS prophylaxis but there is paucity of data validating its efficacy.
Aim:
The primary aim of the study was to evaluate the CNS relapse rates in DLBCL patients who received CNS prophylaxis.
Patients and Methods:
This was a single-centre retrospective observational study conducted in a district general hospital. Data was extracted from the regional (Dorset Cancer Network) DLBCL database and laboratory reports for CSF analysis at the time of the first intrathecal chemotherapy. Medical records of patients with DLBCL who received CNS prophylaxis were evaluated for the following patient-related and disease-related demographics: age at diagnosis, gender, stage, systemic treatment, CNS prophylaxis, treatment response, remission duration, systemic relapse rates, CNS relapse rates and survival. CNS-IPI scores were retrospectively calculated and additional indications evaluated for patients who received CNS prophylaxis.
Results:
Between 2013 and 2018, 178 patients were diagnosed with DLBCL. All patients were treated with RCHOP chemo-immunotherapy. CNS prophylaxis was administered in 47 (26%) patients. Median age was 69 years (range 20-86 years) and 62% were males. All 47 patients (100%) received IT methotrexate as CNS prophylaxis, with 43 (91%) receiving all of the planned 4 doses of IT methotrexate 12.5 mg each. A CNS-IPI score of ³4 was present in 31 (66%) patients, and a score of 2-3 in 9 (19%) patients. Additional risk factors identified included testicular lymphoma in 3 patients, breast lymphoma in 2 patients and oropharyngeal lymphoma in 2 patients. Ten (21%) patients received their treatment at the outset with courses 1-4 of R-CHOP. Of the 47 patients who received CNS prophylaxis, 5 (10%) relapsed; all had isolated CNS lymphoma at relapse. Median time to CNS relapse was 25 months (range 12-36 months) from initial diagnosis of DLBCL. Median survival after CNS relapse was 5 months (range 2-9 months). Of the remaining 141 patients, 2 patients relapsed with isolated CNS lymphoma.
Conclusion:
Although the overall incidence was low (4%), CNS relapse was observed in 10% of high-risk patients all of whom received CNS prophylaxis with IT methotrexate. The efficacy of CNS prophylaxis with IT chemotherapy remains unproven. There is no randomised study to show that IT prophylaxis alone is effective. Current British guidelines recommend high-dose intravenous methotrexate over IT methotrexate if patient's physiological fitness and renal function are acceptable4. The median age in our cohort was 69 years which makes it challenging to deliver dose-intensive systemic therapy concurrently with intravenous high-dose methotrexate. The role of CNS prophylaxis in high-risk patients including its efficacy and safety in older patients need further evaluation in prospective randomised studies.
References Eyre T et al.Efficacy of central nervous system prophylaxis with stand-alone intrathecal chemotherapy in diffuse large B-cell lymphoma patients treated with anthracycline-based chemotherapy in the rituximab era: a systematic review. Hematologica. 2019;105(7):1914-1924.Norbert Schmitz et al.CNS International prognostic Index: A risk model for CNS relapse in patients with diffuse large B-cell lymphoma treated with R-CHOPJ Clin Oncol 2016; 34:3150-3156.Andrew D Zelenetz et al.National Comprehensive Cancer Network (NCCN) Guidelines: B-Cell Lymphomas.Version 2.2020.Pamela McKay et al.The prevention of central nervous system relapse in diffuse large B-cell lymphoma: a British Society for Haematology good practice paper. Onlinelibrary.wiley.com. 2020. Available from: https://onlinelibrary.wiley.com/doi/epdf/10.1111/bjh.16866

Disclosures
Hall: Janssen:Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: sponsored for educational meetings;Karyopharm:Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: sponsored for educational meetings;Takeda:Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: sponsored for educational meetings;Celgene:Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: sponsored for educational meetings.Killick:Celgene:Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Support for attending educational meetings;Jazz Pharmaceuticals:Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Support for attending educational meetings;Novartis:Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Support for attending educational meetings;Gilead:Honoraria, Other: Support for attending education meetings.McCarthy:Janssen:Honoraria;Abbvie:Membership on an entity's Board of Directors or advisory committees.Walewska:AbbVie:Other: sponsored for educational meetings, Speakers Bureau;Janssen:Other: sponsored for educational meetings, Speakers Bureau;Gilead:Speakers Bureau;Astra Zeneca:Membership on an entity's Board of Directors or advisory committees.Chacko:Astellas:Honoraria;Daiichi-Sankyo:Honoraria;Novartis:Honoraria, Other: Travel Grants;Gilead:Other: Travel grants;Jazz Pharmaceuticals:Other: Travel grants;Celgene:Other: Travel grants.