Evaluation of Single Agent Lenalidomide in Patients with Newly Diagnosed Multiple Myeloma (NDMM).

Lenalidomide (Len) is an immunomodulatory drug with antitumor effects mediated through activation of T and NK cells as well as modulation of tumor cytokine environment. Currently Len is approved in combination with dexamethasone (dex) for treatment of patients with relapsed myeloma. Interestingly, in NDMM, higher 1 and 2 year survival rates were observed when the dose of dex was reduced compared to standard high dose dexamethasone and Len (Rajkumar et al. 2008). The immune suppressive effects of dex can antagonize Len immunomodulatory activity and may explain this observation. To our knowledge, Len has not been evaluated as a single agent in NDMM.

Records of patients with newly diagnosed symptomatic multiple myeloma treated with single agent Len at H. Lee Moffitt Cancer Center and Roswell Park Cancer Institute were reviewed (after IRB approval at both institutions). Data was collected on disease characteristics, demographics and treatment outcomes. Responses assessed as per the IMWG criteria.

From March 2007 to July of 2009, 18 patients with NDMM have been treated with Len alone. The median age was 70 years (range 46-84), and 12/18 were males. Heavy chain was IgG in 12 and IgA in 4 patients with 2 patients with light chain myeloma. The involved light chain was kappa in half the patients. Clinical stage of patients included stage IIIA (n=13), IIA (n=4) and IA (n=1) using the DS system whereas as per the ISS system 10, 6 and 2 has stages I, II and III respectively. Cytogenetics were not available on most patients (11); and 4 of 7 patients with available cytogenetics had deletion 13q identified by FISH. The median b2m was 2.8 mg/L (range 2.1-10.7) with >3.5mg/L in 7/18 patients. All except one patient (with a creatinine clearance of 49 ml/min) were started on Len 25 mg daily for 21 days of a 28 days cycle. As of August 1^st 2009, 3 patients are inevaluable for response due to short follow up. Among the remainder 15 patients, 3 achieved a CR (1 stringent CR), 2 VGPR, 3 PR, 4 had MR with SD in additional 3 patients. Thus MR or better response was noted in 80% of patients. The median time to first response was 55 days (range 28-98) and median time to best response was 73 days (range 31-591). After a median follow up of 7 months (range 1-26), 1 patient died of progressive disease (despite the addition of dexamethasone and subsequent bortezomib therapy), 4 patients required the addition of dexamethasone. Len was generally well tolerated and no grade 4 hematologic toxicity were noted, 1 patient had grade 3 neutropenia, 1 patients grade 3 anemia and 2 patient grade 3 thrombocytopenia. Four patients had Len dose reduced.

Single agent Len appears to be an effective therapy in newly diagnosed myeloma patients (MR and better in 80% of patients) and should be evaluated in a prospective fashion in an attempt to decrease corticosteroid toxicity in a group of vulnerable patients and potentially enhance the immunomodulatory activity of Len. Our experience suggests that single agent Len can be effectively employed as an initial step in sequencing anti-myeloma regimen(s) for treatment of NDMM.

Baz:celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding. Off Label Use: lenalidomide as a single agent in newly diagnosed myeloma. Hussein:Celgene: Employment.