Study of Older Patients with Primary Central Nervous System Lymphoma (PCNSL): Comparison of High-Dose Chemotherapy Followed by Autologous Stem Cell Transplantation with Conventional Chemotherapy Using R-MP (Rituximab + Methotrexate + Procarbazine)

Primary diffuse large B-cell lymphoma of the central nervous system (PCNSL) is a rare cancer that affects the central nervous system—that is, the brain, spinal cord, and eyes. It occurs primarily in older adults and has a poor prognosis. Nevertheless, the goal of treatment is a cure. The current standard of care is divided into an induction and a consolidation phase. This means that treatment begins with an initial therapy consisting of a combination of various chemotherapy drugs such as rituximab, methotrexate, and procarbazine (R-MP). The goal of this therapy is to rapidly reduce the cancer. This is followed by maintenance chemotherapy with procarbazine, which is intended to stabilize the treatment response achieved over the long term and thus reduce the risk of relapse.

The goal of the PRIMA-CNS study is to investigate an alternative treatment approach compared to the current standard of care, which combines a shorter but more intensive induction chemotherapy regimen of rituximab, methotrexate, and cytarabine (R-MTX-AraC) combined with high-dose chemotherapy followed by autologous stem cell transplantation (HCT-ASCT). In this method, the patients’ own blood stem cells are collected during therapy and reinfused after high-dose chemotherapy to restore blood production. This is a randomized, interventional Phase 3 trial. This means that patients are randomly assigned to one of two treatment groups after all patients have received the same induction therapy consisting of one cycle of rituximab and methotrexate. One group of patients receives the current standard of care, while the comparison group receives the alternative treatment approach described above. The goal is to compare the two treatment approaches in terms of their efficacy (measured by progression-free survival—the period during which the cancer has not progressed and no new tumor sites have developed) and safety, in order to determine which therapy is more beneficial. This study is particularly relevant because older PCNSL patients have a poorer prognosis due to other medical conditions and reduced tolerance for intensive therapies. The results could help optimize treatment strategies for this patient group.

Eligible participants include women and men aged 65 and older with a newly diagnosed primary diffuse large B-cell lymphoma of the central nervous system (PCNSL). The disease must affect only the central nervous system and must be confirmed by a biopsy or cerebrospinal fluid analysis. Patients must be in good general health (ECOG ≤ 2) and, from a medical standpoint, be eligible for high-dose chemotherapy. Furthermore, the disease must not have progressed during prior therapy. Patients with immunodeficiency (e.g., HIV, organ transplantation) or lymphoma that has already spread outside the CNS are excluded. Other exclusion criteria include other cancers within the past five years (except for early-stage cancers that have been completely cured), severe kidney, heart, lung, or liver disease, active hepatitis B or C, and recent participation in another clinical trial.