QLTI-03. REAL-WORLD PARADIGM FOR TREATMENT OF PRIMARY CNS LYMPHOMA PATIENTS IN CLINICAL PRACTICE

Abstract Although high-dose methotrexate (HD-MTX) is the foundation of induction therapy for primary CNS lymphoma (PCNSL), a gold-standard regimen has yet to be established. A 10-case-based survey, to assess the practice patterns at key decision-points in adult PCNSL management outside of clinical trials, was distributed through IPCG, HOVON, and AAN Neuro-Oncology Section. Eighty-five responses were collected from North American (N=42), European (N=33), Asian (N=7), and other countries (N=3) from neurologist neurooncologists (N=35), hem-onc neurooncologists (N=24), hematologist-oncologists (N=18), neurosurgeons (N=5), radiation-oncologist (N=2), and hematopathologist (N=1). The most common first-line induction regimen was R-MP+/-V: rituximab, HD-MTX, procarbazine, +/-vincristine (N=28) followed by MATRix: HD-MTX, cytarabine, thiotepa, rituximab (N=23), then R-MT: rituximab, HD-MTX, temozolomide (N=19). For elderly patients, R-MP+/-V remained most common (N=32). The majority preferred to omit intra-CSF chemotherapy (N=50). The most preferred consolidation after complete response was high-dose chemotherapy and autologous stem-cell transplantation (HDC-ASCT, N=57), or high-dose cytarabine (N=17) in elderly patients. In cases of partial response, the most common approach was still HDC-ASCT (N=24). For stable disease, participants would move to various salvage chemotherapy (N=33), continue additional induction (N=39), or to move to radiotherapy (N=10). If early progression was noted, the most preferred approach was non-methotrexate chemotherapy (N=31). For recurrences after previous complete response and HDC-ASCT consolidation, the majority preferred to try chemotherapy before moving to radiotherapy in scenarios < 1 year (N=64) or > 1 year from consolidation (N=68), and even if the performance status was poor (N=57). Close to half (N=34) participants felt there is a role for stereotactic radiosurgery in various clinical settings. This survey noted clear consensus to use multi-drug MD-MTX based chemotherapy, and common induction regimens, however, highlighted a great variety of treatment preferences after first-line therapy even amongst disease experts through clinical consortiums, suggesting likely wider range of treatments and disease response in larger community settings.