Patients with acute lymphoblastic leukaemia or very aggressive lymphoma and documented isolated CNS relapse or CNS relapse combined with other relapse sites should receive therapy with intrathecal DepoCyte at least once. Treatment may be repeated during induction phase each 2 weeks and monthly during maintenance phase. The study aim is to replace the usual 2-3 weekly applications of intrathecal triple therapy with one application of DepoCyte. Primary objective is the response rate after one application of DepoCyte. Further objectives are the compilation of data regarding safety and toxicity

Inclusion Criteria:

• proven diagnosis of ALL or very aggressive Non-Hodgkin-Lymphoma (Burkitt/Burkitt-like) and CNS relapse
• CNS involvement demonstrated by a positive ventricular or lumbar CSF cytology or characteristic signs and symptoms of neoplastic meningitis plus an MRI or CT scan indicating the presence of meningeal involvement
• in combined relapse in CNS and other locations: systemic therapy with CNS active drugs can be postponed for at least 2 weeks
• Karnofsky Performance Score is > or = 60%
• 18 years of age or older
• free of uncontrolled infection
• recovered from any grade III / IV toxicities attributable to prior treatment with the exception of hematotoxicity
• patient not pregnant or breast feeding and effective methods to prevent pregnancy
• free from severe heart, lung, liver or kidney dysfunction
• written informed consent

Exclusion Criteria:

• failed to respond (as defined by no clearance of the CSF) to > 1 dose of prior i.th. MTX or ARAC or triple therapy
• history of neurotoxicity (grade III - IV) attributed to i.th. or systemic HD therapy with MTX or ARAC
• prior CNS relapse < 1 month before