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Positive Phase III Results Reported for Ofatumumab (Arzerra) as Maintenance Therapy for Relapsed CLL

Treatment achieves significance level for efficacy

According to an independent data monitoring committee (IDMC) interim analysis, the phase III PROLONG trial has reached the predefined significance level for efficacy (P ≤ 0.001).

The interim analysis demonstrated that treatment with ofatumumab (Arzerra, GlaxoSmithKline/Genmab) met the study’s primary endpoint of improving progression-free survival (PFS) as maintenance therapy compared with no further treatment (observation) in patients with relapsed chronic lymphocytic leukemia (CLL) who responded to treatment at relapse.

The IDMC will continue to monitor the patients for safety until all study patients complete therapy. Further analysis of the safety and efficacy data is under way.

In the pivotal PROLONG trial, 532 patients with relapsed CLL who had responded to treatment at relapse were randomly assigned to receive either ofatumumab maintenance treatment or no further treatment (observation). The patients in the ofatumumab arm received an initial dose of 300 mg of ofatumumab, followed 1 week later by a second dose of 1,000 mg, and then doses of 1,000 mg every 8 weeks for up to 2 years. Patients in the observation treatment arm receive no further treatment.

In addition to the primary endpoint of PFS, secondary objectives included clinical benefit, safety, tolerability, health-related quality of life, and pharmacokinetics among relapsed CLL patients receiving maintenance therapy with ofatumumab compared with observation only.

Ofatumumab is a monoclonal antibody designed to target CD20 molecules on the surface of CLL cells and normal B lymphocytes. In the U.S., it is approved for use in combination with chlorambucil for the treatment of previously untreated patients with CLL for whom fludarabine-based therapy is considered inappropriate.

The overall safety profile of ofatumumab in CLL (previously untreated and relapsed or refractory) is based on data from more than 500 patients treated alone or in combination with other therapies in clinical trials.

The most common adverse events associated with ofatumumab included infusion reactions, cytopenias (i.e., neutropenia, anemia, febrile neutropenia, thrombocytopenia, and leukopenia), and infections (i.e., lower respiratory tract infection, including pneumonia; upper respiratory tract infection; sepsis, including neutropenic sepsis and septic shock; herpes virus infection; and urinary tract infection).

CLL, the most commonly diagnosed adult leukemia in western countries, accounts for approximately one-third of all cases of leukemia. In the U.S., it is estimated that more than 105,000 people currently live with or have been previously treated for CLL and that an estimated 15,680 new cases of CLL were diagnosed in the past year. The average age at diagnosis is 72 years, and approximately 90% of patients with CLL are estimated to be over 55 years of age. Most patients with CLL have at least one co-morbid condition, such as hypertension, diabetes, cardiovascular disease, or chronic obstructive pulmonary disease (COPD).

Source: GlaxoSmithKline; July 31, 2014.

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