Ovarian cancer has the highest mortality rate among gynaecological tumours despite the fact that the majority of patients with advanced disease achieve complete remission after first-line surgery and
chemotherapy. Unfortunately, disease recurrence occurs in the majority of patients and second-line treatments are not curative. Clearly, the persistence of dormant and drug-resistant cells after front-line treatments results in the inability to cure the disease. The identification of
cancer-initiating cells or cancer stem cells as key players in the development of recurrence has opened up a novel field of research aimed at identifying additional innovative therapeutic approaches. Strategies of maintenance
therapy to extend the survival of patients have been studied, but to date no overall survival benefit has been detected. Currently, numerous clinical trials have just been completed or are ongoing involving patients achieving a complete clinical response after first-line
chemotherapy in order to evaluate the efficacy of different therapeutic approaches in terms of disease-free survival and overall survival. At the 2010 ASCO meeting, the first positive results of a phase III clinical trial in this setting were presented:
bevacizumab (15 mg/kg i.v. every 21 days) added to first-line
chemotherapy and continued for an additional 15 cycles was found to prolong progression-free survival of 3.8 months in comparison to 6 cycles of
chemotherapy alone or only 6 cycles of
chemotherapy plus
bevacizumab. In addition, positive results were announced for a second phase III trial testing
bevacizumab in the same setting, but at half dose. The final assessment of the overall clinical benefit and the approval of
bevacizumab in maintenance
therapy by regulatory agencies is expected to be positive, as are the final results of
abagovomab phase III trial MIMOSA, another antibody-based
therapy tested as a maintenance treatment for advanced
ovarian cancer patients. Encouraging preliminary results confirming the safety profile and the immunogenic activity of
abagovomab were presented at the last ASCO meeting. The final results are expected to be released in the first half of 2011.