The aim of this trial is to determine the appropriate dose of pixantrone to be used in this combination and obtain data on the combination's safety and activity profile.

The FND-R regimen is commonly used in the treatment of indolent Non-Hodgkin's lymphoma (NHL) and contains the chemotherapy agents mitoxantrone, fludarabine, dexamethasone (a steroid) and the monoclonal antibody rituximab. In this trial we are replacing mitoxantrone with pixantrone, an agent with a similar chemical structure (both agents are DNA intercalators). The trial is being run in patients with relapsed or refractory indolent NHL and aims to define the appropriate dose of pixantrone to be used in this combination, as well as to obtain data on pixantrone's safety and activity profile in combination with these drugs.

This trial is expected to recruit up to 30 patients in the USA. Patients will be treated with the drug combination for up to eight months and then followed closely in the four-week period after the last administration. After that, patients will receive physician check-ups every three months.

Inclusion criteria

• Patients with relapsed or refractory indolent (low-grade) NHL
• Who have received 1-3 prior treatments with chemotherapy

Exclusion criteria

• Patients previously treated with fludarabine
• Prior treatment with rituximab (Rituxan), unless there was a complete response (CR) or partial response (PR) to that treatment
• Patients known to have an allergic reaction to rituximab, or to murine proteins.