Multiple myeloma (MM) is an incurable disease that is characterized by the accumulation of clonal plasma cells in the bone marrow. The median overall survival for patients with MM is approximately 4-5 years. Despite front line treatment approaches, the disease eventually relapses. The recent US Food and Drug Administration (FDA) approvals of bortezomib (2003) and combination lenalidomide plus dexamethasone (2006) therapies for the treatment of previously treated MM has provided effective therapeutic options that give patients with relapsed or refractory MM the prospect for a prolongation of overall and progression-free survival times. However, MM remains an incurable disease. A clear unmet medical need still exists for additional novel therapeutic options for the treatment of previously treated MM.
Pomalidomide belongs to the IMiDs class of compounds which thalidomide is the parent compound and lenalidomide the most recently approved agent. It is derived from thalidomide and shares a number of the beneficial pharmacologic properties with thalidomide. The efficacy of thalidomide has been limited by adverse effects. This toxicity profile seems dose and duration-related, spurring the development of IMiDs, which have the potential of improved potency and reduced toxicity. By modifying the thalidomide structure through the addition of an amino group at the 4 position of the phthaloyl ring to generate pomalidomide, a compound that is up to 50000 times more potent at inhibiting TNF-alpha than thalidomide was formed.
Recently, preliminary efficacy and safety data from an ongoing phase 2 study, led by Martha Lacy, et al, at Mayo Clinic, were presented at the XII International Myeloma Workshop in Washington DC (01 March 2009). The study highlighted a 63 % objective response and a 5% complete response in patients taking pomalidomide (2 mg daily on days 1-28 of a 28-day cycle) plus dexamethasone (40 mg daily on days 1, 8, 15, 22 of each cycle) including patients with lenalidomide resistant refractory multiple myeloma. The results also showed that the treatment was well tolerated. Based on the encouraging data of this study, a phase 1/2b multi-center, randomized, open-label, dose escalation study (dose level from 2 mg to 5 mg daily on days 1-21 of a 28-day cycle)is conducted to determine the MTD of pomalidomide. This ongoing study will evaluate the safety and efficacy of oral pomalidomide alone, and in combination with dexamethasone, in patients with relapsed and refractory MM. The first results obtained in this study demonstrated that the maximum tolerated dose of pomalidomide was 4 mg once per day and highlighted that pomalidomide has significant efficacy in MM and can be safely administered to myeloma patients. Moreover, there are an increasing number of patients who are refractory or did not respond significantly or experienced significant toxicity to either bortezomib or lenalidomide.
Based on these studies, we hypothesized that these patients might benefit from the combination of pomalidomide and dexamethasone. We have therefore designed a multicenter phase 2 randomized open labelled study to determine response to pomalidomide and dexamethasone in relapse and refractory MM patients who are progressive and did not achieve at least a partial response to bortezomib and lenalidomide. This study will determine the efficacy and toxicity profile of 2 modalities of pomalidomide in patients with advanced myeloma, previously heavily treated characterized with adverse prognostic and that are in desperate need of novel therapeutics. This study will be conducted in accordance with "good clinical practice" (GCP) and all applicable regulatory requirements, including, where applicable, the 2008 version of the Declaration of Helsinki.
