The preliminary findings of a Phase 3 trial suggest that Revlimid (lenalidomide) improves the complete response rate in multiple myeloma patients who had undergone an autologous stem cell transplant (ASCT). Researchers presented the results of the trial at the American Society of Hematology’s annual meeting in December 2009.

In mid-January, Celgene further announced that, based on an interim analysis reviewed by an independent committee, the Phase 3 trial has met an additional primary endpoint. Patients on Revlimid showed better progression-free survival than patients on a placebo. Final results will be presented at a major medical meeting later this year.

In recent years high-dose chemotherapy followed by an ASCT has become a standard treatment option for younger patients with newly diagnosed multiple myeloma. The patients receive high-dose chemotherapy which destroys both the myeloma cells and healthy stem cells. After chemotherapy, the patients receive an autologous stem cell transplant, in which the patients’ own stem cells that were collected before high-dose chemotherapy are transplanted back into the patients. In tandem transplantation, the entire process is repeated twice.

While high-dose chemotherapy followed by stem cell transplantation extends survival and improves response rate, many patients eventually relapse; thus, scientists are looking for new strategies to control the disease.

Post-transplant therapies, such as thalidomide (Thalomid) plus prednisone, have shown to increase both response rate and survival time; however, side effects, such as nerve damage in the limbs, were a major limitation of the thalidomide plus prednisone regimen. Because of its similarities to thalidomide, researchers decided Revlimid might offer the same benefits as a post-transplant therapy without the side effects associated with the thalidomide plus prednisone therapy.

For their study, researchers recruited 614 patients who had undergone an ASCT within the previous six months and treated all of them with two months of Revlimid (25 mg/day for 21 days each month), referred to as consolidation therapy, followed by either a lower dose Revlimid (10 to 15 mg/day) or a placebo, referred to as maintenance therapy, until relapse.

The researchers compared patient response rates before and after consolidation therapy. Of the 614 patients participating, 435 (80 percent) were able to receive the consolidation therapy at the dosage and schedule planned. Data for 412 patients were available for analysis.

Before receiving Revlimid consolidation therapy, 104 patients (25 percent) had achieved partial response; 206 (50 percent) achieved very good partial response; 90 (22 percent) achieved complete response; and nine (2.2 percent) achieved stringent complete response. Three participants (0.7 percent) remained stable.

Sixty patients (15 percent) improved their response after consolidation therapy. Eight patients (2 percent) advanced to stringent complete response, 33 (8.2 percent) to complete response, and 18 (4.5 percent) to very good complete response. The nine patients who had already reached stringent complete response before consolidation were not included in the post-consolidation analysis since they could not improve their response any further.

Seventy-four patients (12 percent) experienced severe side effects, such as blood disorders, allergic reactions, infections, fatigue, and clotting in the veins.

Researchers concluded that Revlimid can be administered as consolidation therapy for two cycles at the dose tested and that it significantly improves the rate of complete response or better.

For more information, please see abstract 529 at the ASH meeting Web site, the Celgene press release, and the clinical trial description.