Genmab A/S has announced the New England Journal of Medicine (NEJM) has published the full data set from the initial Phase I/II study with daratumumab monotherapy treating patients with relapsed or refractory multiple myeloma. Patients that received 16 mg/kg in part 2 of the study had a median of 4 prior lines of therapy and 64% of these patients were refractory to both proteasome inhibitors (PIs) and immunomodulatory (IMiD) drugs, which are current standard of care treatments for multiple myeloma. The data showed a 36% response rate in the 16 mg/kg group in part 2 of the study, with responses that deepened over time. Sixty five percent of patients in this group that responded to treatment were progression-free twelve months following the start of treatment. For all patients in part 2, pneumonia and thrombocytopenia were the most common grade 3/4 adverse events (AEs; ≥5%). Infusion-related reactions were mild with no dose-dependent adverse events. In part 1 of the study, no maximum tolerated dose was identified up to 24 mg/kg.

Following this study, 16 mg/kg was chosen as the dose to be used in future daratumumab clinical studies. Daratumumab is being developed by Janssen Biotech, Inc. under an exclusive worldwide license to develop, manufacture and commercialize daratumumab from Genmab.

"Patients who have relapsed or refractory multiple myeloma currently have very limited treatment options. The results from this first-in-human study of daratumumab, presented in full in The NEJM, show an impressive response rate and duration of response, particularly when you consider that patients in the study had received a large number of prior treatments," said Jan van de Winkel, Ph.D., Chief Executive Officer of Genmab.

Data from this study has been included in the Biologics License Application (BLA) submitted by Janssen to the U.S. Food and Drug Administration for daratumumab as a treatment for patients with multiple myeloma who have received at least three prior lines of therapy including both a proteasome inhibitor (PI) and an immunomodulatory agent (IMiD) or who are double refractory to a PI and an IMiD. The BLA submission was completed on July 9th 2015.

About the study

This two-part, Phase I/II, open-label study enrolled 32 patients in part 1, and 72 patients in part 2, 42 of which were in the 16 mg/kg dose group. Part 1 was a dose-escalation study with patients receiving weekly doses of daratumumab between 0.005 and 24 mg/kg of daratumumab.

In part 2, 8 mg/kg and 16 mg/kg daratumumab were administered with different schedules. The primary endpoint of the study was safety. Secondary endpoints were pharmacokinetics, objective response according to International Myeloma Working Group (IMWG) uniform response criteria for myeloma, relative reductions in M-protein and free light chains, time to progression, response duration, progression-free and overall survival.

About multiple myeloma

Multiple myeloma is an incurable blood cancer that starts in the bone marrow and is characterized by an excess proliferation of plasma cells.1 Multiple myeloma is the third most common blood cancer in the U.S., after leukemia and lymphoma.2 Approximately 26,850 new patients will be diagnosed with multiple myeloma and approximately 11,240 people will die from the disease in the U.S. in 2015.3 Globally, it is estimated that 124,225 people will be diagnosed and 87,084 will die from the disease in 2015.4 While some patients with multiple myeloma have no symptoms at all, most patients are diagnosed due to symptoms which can include bone problems, low blood counts, calcium elevation, kidney problems or infections.5 Patients who relapse after treatment with standard therapies, including PIs or IMiDs, have poor prognoses and few treatment options.6

About daratumumab

Daratumumab is an investigational human IgG1k monoclonal antibody (mAb) that binds with high affinity to the CD38 molecule, which is highly expressed on the surface of multiple myeloma cells. It induces rapid tumor cell death through multiple immune-mediated mechanisms7, including complement-dependent cytotoxicity7, antibody-dependent cellular phagocytosis8 and antibody-dependent cellular cytotoxicity7, as well as via induction of apoptosis9. Five Phase III clinical studies with daratumumab in relapsed and frontline settings are currently ongoing. Additional studies are ongoing or planned to assess its potential in other malignant and pre-malignant diseases on which CD38 is expressed, such as smoldering myeloma and non-Hodgkin lymphoma. Daratumumab has been granted Breakthrough Therapy Designation from the US FDA.