New data released recently by Genmab A/S (Denmark) has indicated that ofatumumab maintenance therapy could have an impact on the progression-free survival (PFS) of patients with relapsed chronic lymphocytic leukemia (CLL). The data will be presented at the 56th Annual Meeting of the American Society of Hematology (San Francisco, CA, USA) on December 6th 2014.
CLL is the most commonly diagnosed adult leukemia in Western countries, and in excess of 105,000 people either currently suffer from or have been treated for the disease in the USA. On average, patients are diagnosed at 72 years of age, and approximately 90% of individuals with the disease are over 55 years of age.
Ofatumumab, a monoclonal antibody that targets the CD20 molecule on the surface of CLL cells and normal B lymphocytes, is not currently approved or licensed as maintenance treatment for relapsed CLL. The Genmab A/S Phase III study of ofatumumab, PROLONG, investigated ofatumumab maintenance therapy versus no additional treatment in patients who exhibited a complete or partial response after second or third line treatment for CLL.
A total of 474 patients were included in this interim analysis of the PROLONG study. The results demonstrated that those who received ofatumumab maintenance treatment lived 13.4 months longer without their disease condition worsening (median PFS) than those patients who received no further treatment. For the ofatumumab treatment arm and observation arm, median PFS was 28.6 months and 15.2 months, respectively (hazard ratio: 0.48; p < 0.0001).
Furthermore, the period of time until a patient needed to start treatment again was significantly longer for those in the ofatumumab arm than the no treatment arm (38.0 vs 27.4 months; hazard ratio: 0.63; p = 0.0076).
No unexpected safety concerns were observed during the trial. Adverse events occurred in 87% of patients in the ofatumumab treatment arm, versus 75% pf patients in the observation treatment arm. . For patients in the ofatumumab treatment arm, 25% experienced grade 3–4 adverse events compared with 17% in the observation arm. The two most commonly seen grade 3–4 adverse events were neutropenia (22 in the ofatumumab arm vs 9% in the observation arm) and pneumonia (7 vs 4%). The death rate was observed as similar in both study arms (14%).
Jan van de Winkel, the Chief Executive Officer of Genmab, commented: “The interim results of this study show that ofatumumab maintenance therapy significantly extended the amount of time the patients in the study lived without their CLL symptoms getting worse.”