Danish biotechnology firm Genmab has reported data from the Phase II trial (Sirius MMY2002) of daratumumab in patients with relapsed and refractory multiple myeloma.
Daratumumab is a human IgG1k monoclonal antibody (mAb). It is being developed by Janssen Biotech under an exclusive worldwide licence from Genmab to develop, manufacture and commercialise the product.
The drug binds with high affinity to the CD38 molecule, which is highly expressed on the surface of multiple myeloma cells.
124 patients were involved in the two-part trial, which took place in Canada, Spain and the US.
The patients were given at least three prior lines of therapy, including a proteasome inhibitor and an immunomodulatory agent.
They were randomly allocated in a 1:1 ratio to receive intravenous daratumumab 8mg/kg or 16mg/kg in part 1 of the study, to decide the dose for further assessment in part 2.
Patients received 8mg/kg every four weeks, or 16mg/kg per week for eight weeks (cycles 1 and 2). They then received the doses every two weeks for 16 weeks (cycles 3-6), and then every four weeks thereafter (cycle 7 and higher).
The company noted that patients who received 16mg/kg of daratumumab had a median of five prior lines of therapy, and that 95.3% were refractory to both proteasome inhibitors (PIs) and immunomodulatory drugs, which are current standard of care treatments for multiple myeloma.
Results from the trial showed a 29.2% overall response rate, including three stringent complete responses, ten very good partial responses, and 18 partial responses in patients treated with 16mg/kg of daratumumab.
The median time to respond among patients was one month, while the median response duration was 7.4 months, and median progression-free survival was 3.7 months.
The 12-month, overall survival rate was 64.8% and, at a subsequent cutoff, median overall survival was 17.5 months.
Daratumumab was well tolerated, with fatigue (40%) and anemia (33%) the most common adverse events (AEs). No drug-related AEs led to treatment being discontinued.
Genmab CEO Jan van de Winkel said: "Data from the daratumumab Sirius study illustrates the significant potential of daratumumab in patients with multiple myeloma who have undergone multiple rounds of prior treatment.
"Data from the study, now published in The Lancet, was the basis for the approval of daratumumab in heavily pre-treated or double refractory multiple myeloma by the US FDA."
In November last year, the US Food and Drug Administration (FDA) approved the Darzalex (daratumumab) injection for intravenous infusion to treat patients with multiple myeloma who have received at least three prior lines of therapy.
Eligible patients will have received a proteasome inhibitor (PI) and an immunomodulatory agent, or will have been double-refractory to a PI and an immunomodulatory agent.