BETHESDA, MarylandThe Oncologic Drugs Advisory Committee (ODAC)
has unanimously recommended that the Food and Drug Administration approve the
marketing of Zevalin (ibritumomab tiuxetan, IDEC Pharmaceuticals) for the
treatment of patients with rituximab (Rituxan)-refractory follicular, B-cell
non-Hodgkin’s lymphoma (NHL).
However, by a 10-to-6 vote, the committee failed to recommend that the
agency fully approve Zevalin for the treatment of patients who have not failed
rituximab therapy, including those with relapsed or refractory low-grade
follicular NHL or CD20-positive transformed B-cell NHL. For this indication,
the committee suggested that the FDA consider approval under the agency’s
accelerated approval regulations.
Zevalin is a murine monoclonal antibody linked by a chelating agent to the
radioactive isotope yttrium-90, and it is intended as a complementary drug to
rituximab. Both monoclonal antibodies target the CD-20 surface antigen
expressed on B-lineage tumor cells.
A Two-Part Process
Administering Zevalin is a two-part process. A patient first receives a
single infusion of rituximab (250 mg/m²), followed by indium-111-labeled
Zevalin for imaging. A week later, the patient gets a second infusion of
rituximab at the same dose, followed by a therapeutic infusion of Zevalin (2 mg
of antibody labeled with 0.3 or 0.4 mCi/kg of yttrium-90, depending on the
patient’s baseline platelet count). The maximum Zevalin dose for any patient
is 32 mCi.
A hospital’s nuclear pharmacy prepares the active drug from a kit obtained
from IDEC that contains the monoclonal antibody. The pharmacy then labels the
monoclonal antibody with the yttrium radioisotope obtained from a separate
source. The mixture remains stable for about 8 hours.
"If the committee recommends approval of this product, you should be
aware there are some outstanding manufacturing issues," said Marjorie
Shapiro, PhD, of the FDA’s product review team for Zevalin.