Treatment with Bendamustine, Thalidomide and Prednisolone (BPT) in Patients with Refractory or Relapsed Multiple Myeloma after Autologous Stem Cell Transplantation or Conventional Chemotherapy: Results of a Phase I Clinical Trial.

Thalidomide is an active single agent in advanced relapsed or refractory multiple myeloma (MM). The combination of low dose thalidomide with bendamustine and prednisolone might maintain or increase efficacy of the drug while avoiding dose limiting toxicity (DLT).

Patients and Methods: The treatment consists of a fixed dose of bendamustine (60mg/qm) day 1, 8, and 15 with prednisolone (100 mg) day 1, 8, 15, and 22. In addition, thalidomide is given in three escalating doses, starting with 50 mg to a maximum of 200 mg daily. At each dose level 8 to 12 relapsed or refractory patients, half of them after conventional chemotherapy and half after high dose therapy with stem cell support, were enrolled. Cycles were repeated every 28 days for a minimum of 2 and a maximum of 10 cycles either until a maximal response was achieved, or until a DLT or a disease progression were observed. Between March 2004 and May 2006, 28 patients were enrolled: 8 in the first dose level with 50 mg thalidomide; 8 in the second dose level with 100 mg and 12 in the third dose level with 200 mg. All patients had received a minimum of 2 prior treatment regimens. Seven patients had been refractory to the last treatment. Median age was 67 years (range: 40 – 78). All patients completed 2 cycles of BPT-treatment and are therefore evaluable. Response was assessed using EBMT criteria modified to include near complete remission (nCR) and very good partial remission (VGPR).

Results: Twentyfive of 28 patients responded after at least 2 cycles of chemotherapy with 3 CR, 1 nCR, 5 VGPR, 15 PR and 1 MR. Two patients had stable disease and one patient was refractory. With a median follow up of 15 months, EFS and OS at twelve months were 34 % and 92 %, respectively. The most common side effects were constipation (11 patients WHO grade 1, 8 patients WHO grade 2), polyneuropathy (15 patients WHO grade 1, 3 patients WHO grade 2) and somnolence (4 patients WHO grade 1). None of the 28 patients developed dose-limiting hematoxicity as defined by an ANC < 1,0 Gpt/l for > 7 days or an ANC < 0,5 Gpt/l for > 3 days or platelet count < 25 Gpt/l. Transient neutropenia was reported in 9 patients (WHO grade 3 and 4) but no thrombocytopenia was observed.

Conclusion: BPT with a dose between 50 and 200 mg thalidomide daily is well tolerated in patients with relapsed or refractory MM.