Dr. Oliver Dorigo of the Stanford University Medical Center was the medical source for an article featured in Oncology. Dr. Dorigo explained that if a woman with ovarian cancer has been diagnosed as “platinum sensitive,” her cancer will generally respond favorably to platinum-based chemotherapy. Further, in the event of a relapse, she can still be treated with the same chemotherapy.
About Platinum Sensitivity
The role of platinum sensitivity is still evolving. The current guide used by physicians involves a treatment-free period of a minimum of six months after previous chemotherapy before re-treatment with platinum-based chemotherapy.
Women who require treatment prior to six months are considered to be “platinum-resistant” in that their cancer will not respond to the therapy. As they are not eligible for the platinum-based treatment, their doctors would have to rely on other options.
Options if Platinum-Sensitive
One of the platinum chemotherapies used most often in ovarian cancer is Carboplatin. The drug is generally combined with non-platinum drugs such as Taxol, Doxil, Doxylamine, or Gemzar.
Any platinum-based drugs may be effective on tumors as a second or third therapy if a woman has platinum-sensitive ovarian cancer.
Options if Platinum-Resistant
If a woman’s cancer is platinum-resistant, a doctor may change the dosing intervals of Taxol from every three-week cycle to, for example, every week. The doctor may also add other drugs such as Doxil or Gemzar in combination with Taxol.
Looking at the broad picture, any of the aforementioned drugs may be combined with Avastin, a non-platinum drug. Avastin (bevacizumab) is a vascular endothelial growth factor (VEGF) inhibitor. The drug targets the protein repair process rather than DNA repair.
By blocking the VEGF process of protein repair, blood vessel growth is disrupted. This cuts off a malignancy’s oxygen and subsequently its development. The process is called anti-angiogenesis which blocks new blood vessels from growing out of existing blood vessels. When nutrients and oxygen are blocked it “starves” the tumors.
Zejula Granted FDA New Indication Approval
An article featured in Clinical Oncology News reported that Zejula (niraparib) maintenance therapy was approved for women who have advanced epithelial (tissue covering most surfaces of the body) ovarian cancer.
Zejula is a once-daily oral poly (ADP-ribose) polymerase (PARP) inhibitor, a type of enzyme involved in many functions of the cell. The PARP has been approved for the treatment of patients who have demonstrated a partial or complete response to platinum-based chemotherapy with or without evidence of the BRCA mutation.
About Phase 3 PRIMA Study
FDA approval was based on data from the PRIMA study that enrolled newly diagnosed patients with advanced ovarian disease. The patients were selected following partial or complete response to platinum-based chemotherapy without regard to biomarker status.
Note that biomarkers are substances that give an indication of the state of an organism. A biomarker may be blood pressure, imaging, or even the potential hazards and effectiveness of a particular therapy.
Dr. Bradley Monk, the PRIMA study investigator, offered his opinion. He suggests that Zejula is an appropriate maintenance option for ovarian patients who demonstrated a positive response to the initial platinum-based chemotherapy. He believes that this option is preferable to active surveillance.
About the PRIMA Clinical Trial
Patients were administered an initial dose of 300mg of Zejula once each day. The dose was eventually adjusted later in the study to be determined in accordance with a patient’s weight or platelet count.
The initial dose given for recurrent ovarian cancer or late-line treatment is 300 mg once each day.
About the Primary End Point
Women with ovarian cancer exhibiting homologous recombination deficiencies (HRD) generally have positive responses to therapies. Having HRD indicates that the patient’s ovarian cancer cells have difficulty repairing themselves and are easier to target.
Therefore, women who have the BRCA gene and HRD may find increased benefits from specific chemotherapy drugs as well as PARP inhibitors.
The goal of the PRIMA study (primary endpoint) was PFS or progression-free survival. Results of the study showed a fifty-seven percent risk reduction in disease progression or death when compared to a placebo.
With respect to Zejula’s safety profile, common grade three or higher symptoms were anemia, neutropenia (low neutrophil count), and thrombocytopenia (low platelet count).
In conclusion, Zejula maintenance therapy has shown to be safe and effective.