Safety and Efficacy of a Six Month Full Dose Lenalidomide Consolidation Treatment After First-Line High-Dose Therapy in Patients with Multiple Myeloma

Consolidation with 2 cycles of 25 mg lenalidomide and/or maintenance treatment with a dosage of 10–15 mg lenalidomide after high-dose therapy (HDT) and autologous stem cell transplantation (SCT) improves event-free survival (EFS) in patients with multiple myeloma (MM), as has been shown recently by two randomised clinical trials in the US and France with patients up to the age of 70 and 65, respectively. So far data on longer consolidation treatment and different dosages in the maintenance setting is lacking.

In the randomized, open label phase III LenaMain trial (clinical trials gov: NCT00891384) patients up to the age of 75 years are treated with six cycles of lenalidomide consolidation at a full dosage of 25 mg starting three months after first-line treatment with HDT and autologous SCT. After consolidation patients receive maintenance treatment with either lenalidomide 5 mg or 25 mg, both until disease progression. Here we present data of an interim safety analysis of the consolidation phase of the study. The trial is conducted in 4 transplant centers in Germany und plans to enrol 194 patients.

Enrolment started in April 2009, and interim safety analysis was conducted in September 2011 with the first 68 patients enrolled and 50 patients finishing the consolidation phase. Myeloma subtype was IgG, IgA, others in 55, 23, 23% of patients, respectively, who had a median age of 64 years (range 37–73) and an ISS stage of I in 50%, II in 27% and III in 23% of cases at the time of diagnosis. All patients were treated with a median of 3 (range: 1–6) cycles of induction treatment followed by cytotoxic stem cell mobilisation with cyclophosphamide (4g/m²) and HDT and autologous SCT. Thirty-seven patients younger than 66 yrs received conditioning with melphalan 200 mg/m², which was repeated in 7 patients not achieving at least a very good partial response. Tandem-HDT with melphalan 100 mg/m²was used for 32 patients older than 65 yrs. A median of 113 days (range:56–153) after the last HDT, consolidation treatment with lenalidomide 25 mg daily for 21 days of a 28 days cycle was initiated. All patients received aspirin for prevention of deep-vein thrombosis.

Response rates at baseline 3 month after HDT for sCR, CR, vgPR, PR, MRSD, PD were 0%, 14%, 53%, 31%, 2% and 0%, respectively. Three patients developed an early relapse during the six cycles of consolidation therapy. After cycle 6 of consolidation treatment response rates for sCR, CR, vgPR, PR, MRSD, PD were 10%, 16%, 41%, 24%, 2% and 7%, respectively. The remission status was improved in one third of patients.

After 6 cycles of consolidation treatment 4 patients had discontinued treatment due to AEs, 2 patients withdrew consent and sudden death of unknown cause occurred in one patient during cycle 1. A lenalidomide dosage of 25 mg for 6 cycles could be applied to 53% of patients. Dose reductions were necessary in 47% of patients. Lenalidomide dosage after cycle 6 was 20 mg, 15 mg, 10 mg and 5 mg in 21%, 6%, 15%, and 2% of patients, respectively. The most common hematologic AE was neutropenia (Grade 1–2 in 42%, Grade 3–4 in 39%). Anemia (Grade 1–2: 88 %, Grade 3–4: 3%) and thrombocytopenia (Grade 1–2: 67 %, Grade 3–4: 7 %) occurred less frequently. No bleeding AE was documented. Infectious complications were seen in 59% of patients including 7% with Grade 3–4. Non-hematologic toxicity was low, and Grade 3–4 AEs included pain (2%), skin symptoms (2%), and neurological and constitutional symptoms (7%). There was no statistically significant difference in toxicity and tolerated dosage between patients younger or older than 65 years.

Dose-escalation with lenalidomide 25 mg for 6 cycles as consolidation treatment was very well tolerated and the toxicity was consistent with published data with lower lenalidomide exposure. This was also true for patients aged 66–75 who did not experience an increased toxicity. Lenalidomide 25 mg for six cycles appears to be an effective consolidation treatment, with approximately one third of patients improving their response status.

Fenk:OrthoBiotec: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Off Label Use: Lenalidomide is not approved for maintenace treament of patients with myeloma. Giagounidis:Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. Kröger:Celgene: Research Funding. Schroeder:Celgene: Travel support Other. Kobbe:OrthoBiotec: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding.