Of 31 previously-treated patients who received elotuzumab 10 mg/kg plus lenalidomide and low-dose dexamethasone, 28 (90%) achieved an objective response. Of 32 previously-treated patients who received elotuzumab 20 mg/kg plus lenalidomide and low-dose dexamethasone, 23 (72%) achieved an objective response. The median time to progression-free survival was not reached after 4.9 months of follow-up.
In the study, grade 3 and 4 adverse events included neutropenia (14%), lymphopenia (14%) and thrombocytopenia (13%). The overall rate of treatment-emergent grade 3/4 adverse events was 56%. The overall rate of grade 3/4 elotuzumab-related adverse events was 24%. Of patients with infusion-related reactions, one patient (1.6%) experienced grade 3 rash within 24 hours of treatment with elotuzumab. There were no grade 4 infusion-related adverse events. The most common elotuzumab-related adverse events were fatigue (21%), pyrexia (14%), lymphopenia (11%), nausea (11%) diarrhea (11%), constipation (10%) and neutropenia (10%).
Multiple myeloma is the second most common blood cancer in the United States, with a 5-year survival rate of approximately 35%. Elotuzumab is an investigational humanized monoclonal antibody specifically directed against CS1, a cell-surface glycoprotein that is highly and uniformly present on multiple myeloma cells.
"There remains a need for more effective and tolerable treatment options for patients with relapsed multiple myeloma, as almost all patients eventually relapse and require further therapy," said Paul G. Richardson, M.D. Clinical Director, Jerome Lipper Center for Multiple Myeloma, Dana-Farber Cancer Institute, lead author and investigator on the study. "The preliminary Phase 2 data presented today support further investigation of the potential role of elotuzumab in combination with lenalidomide and low-dose dexamethasone as a treatment option for patients with relapsed multiple myeloma."
A Phase 3 clinical development program for elotuzumab in relapsed multiple myeloma is expected to be initiated in early 2011.
About the Phase 1b/2 Study
The primary endpoint of the Phase 2 portion of this Phase 1b/2, multicenter, open-label dose-escalation study was ORR according to the IMWG response criteria. Patients were randomized 1:1 to receive elotuzumab either 10 or 20 mg/kg (IV infusion on days 1, 8, 15, and 22 of a 28-day cycle in the first 2 cycles and then days 1 and 15 of subsequent cycles), along with lenalidomide 25 mg PO daily on days 1 to 21 and dexamethasone 40 mg PO weekly. Patients were treated until disease progression or unacceptable toxicity, if earlier. To control potential infusion reactions, patients received methylprednisolone (50 mg IV), diphenhydramine (25–50 mg PO or IV) or equivalent, ranitidine (50 mg IV) or equivalent, and acetaminophen (650–1000 mg PO) 30 to 60 minutes prior to each elotuzumab infusion.
Updated Results from a Second Phase 1b Study also Presented
Updated results from an ongoing Phase 1b study of elotuzumab in combination with bortezomib were also presented at the ASH annual meeting. In this study of elotuzumab plus bortezomib in 27 evaluable patients, 13 patients (48%) had an objective response and 17 patients (63%) achieved a clinical response, defined as minimal response or better using the combined European Group for Blood and Marrow Transplant (EBMT) criteria. Median time to disease progression was 9.46 months in the evaluable population. No dose-limiting toxicities were reported and a maximum tolerated dose was not established. The most frequent elotuzumab-related grade 3/4 AEs were fatigue and thrombocytopenia (7%). Serious adverse events related to elotuzumab included one grade 3 chest pain and one grade 3 gastroenteritis. Twenty patients (71%) experienced one or more infusion reactions. The primary endpoint for this study was the incidence of dose-limiting toxicities in the first treatment cycle for each cohort.
About Multiple Myeloma
Multiple myeloma is a type of cancer that originates in the white blood cells. It is the second most common blood cancer in the United States. In 2010, it is estimated that 20,180 new cases will be diagnosed in the U.S. and that 10,650 people will die from the disease.
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