IELSG30 phase 2 trial: intravenous and intrathecal CNS prophylaxis in primary testicular diffuse large B-cell lymphoma

Primary testicular diffuse large B-cell lymphoma (PTL) is characterized by high risk of contralateral testis and central nervous system (CNS) relapse. Chemoimmunotherapy with intrathecal (IT) CNS prophylaxis and contralateral testis irradiation eliminates contralateral recurrences and reduces CNS relapses. The IELSG30 phase 2 study investigated feasibility and activity of an intensified IT and IV CNS prophylaxis. Patients with stage I/II PTL who had not received treatment received 2 cycles of IV high-dose methotrexate (MTX) (1.5 g/m²) after 6 cycles of the R-CHOP regimen (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone, every 21 days). IT liposomal cytarabine was administered on day 0 of cycles 2 to 5 of 21-day R-CHOP regimen. Contralateral testis radiotherapy (25-30 Gy) was recommended. Fifty-four patients (median age: 66 years) with stage I (n = 32) or II (n = 22) disease were treated with R-CHOP, 53 received at least 3 doses of IT cytarabine, 48 received at least 1 dose of IV MTX, and 50 received prophylactic radiotherapy. No unexpected toxicity occurred. At a median follow-up of 6 years, there was no CNS relapse; 7 patients progressed, and 8 died, with 5-year progression-free and overall survival rates of 91% (95% confidence interval [CI], 79-96) and 92% (95% CI, 81-97), respectively. Extranodal recurrence was documented in 6 patients (in 2 without nodal involvement). In 4 cases, the relapse occurred >6 years after treatment. Causes of death were lymphoma (n = 4), second primary malignancy (n = 1), cerebral vasculopathy (n = 1), unknown (n = 2). Intensive prophylaxis was feasible and effective in preventing CNS relapses.