Phase II trial of syncopated thalidomide, lenalidomide, and weekly dexamethasone in patients with newly diagnosed...

Thalidomide and lenalidomide, in combination with dexamethasone, provide response rates ranging from 63%-79% after 4 cycles of therapy. Because of toxicities such as neuropathy and myelosuppression for thalidomide and lenalidomide, respectively, dose escalation has not been pursued. We evaluated a syncopated regimen of alternating weeks of thalidomide and lenalidomide to determine if a modified schedule allows for fewer dose reductions and, subsequently, superior efficacy. Although well tolerated, this phase II trial did not show superior efficacy compared with conventional dosing and scheduling of these agents.

Over the past decade, the novel agents thalidomide, lenalidomide, and bortezomib have emerged as effective treatment in patients with multiple myeloma (MM). Initially used in the relapse setting, these agents have been incorporated into frontline treatment algorithms. They have been combined in doublets with corticosteroids, in triplets with alkylators, or with each other. Because thalidomide and lenalidomide have different clinical activity and toxicity profiles, we designed a trial to evaluate a syncopated schedule of thalidomide and lenalidomide with weekly dexamethasone in patients with newly diagnosed MM to determine response and toxicity.

Twenty-two patients with newly diagnosed MM were treated with syncopated thalidomide (200 mg on days 1-7 and 15-21), lenalidomide (25 mg on days 8-14 and 22-28 for the first cycle and 50 mg on the same schedule for subsequent cycles) with weekly dexamethasone (40 mg). Each cycle lasted 28 days. MM parameters were assessed at the end of each cycle. It was intended that the patients proceed to stem cell mobilization and autologous transplantation after 4 cycles of therapy.

The median number of cycles administered was 3.5. The overall response was 68%. The regimen was well tolerated by the majority of the patients; only patient discontinued treatment because of toxicity.

We conclude that a syncopated schedule of thalidomide and lenalidomide with weekly dexamethasone was tolerated well, with no unexpected toxicities. However the response rate, even using lenalidomide at 50 mg, was not superior to standard dosing of thalidomide or lenalidomide plus dexamethasone.