A randomized phase II clinical trial showed that the oral PARP inhibitor drug olaparib (AZD2281), given after chemotherapy, improved progression-free survival in women with the most common type of recurrent ovarian cancer.
ASCO Releases Studies From Upcoming Annual Meeting – Important Advances in Targeted Therapies, Screening, and Personalized Medicine
The American Society of Clinical Oncology (ASCO) today highlighted several studies in a press briefing from among more than 4,000 abstracts publicly posted online at http://www.asco.org in advance of ASCO’s 47th Annual Meeting. An additional 17 plenary, late-breaking and other major studies will be released in on-site press conferences at the Annual Meeting.
The meeting, which is expected to draw approximately 30,000 cancer specialists, will be held June 3-7, 2011, at McCormick Place in Chicago, Illinois. The theme of this year’s meeting is “Patients. Pathways. Progress.”
“This year marks the 40th anniversary of the signing of the National Cancer Act, a law that led to major new investments in cancer research. Every day in our offices, and every year at the ASCO meeting, we see the results of those investments. People with cancer are living longer, with a better quality of life, than ever before,” said George W. Sledge Jr., M.D., President of ASCO, Ballve-Lantero Professor of Oncology and professor of pathology and laboratory medicine at the Indiana University School of Medicine.
“With our growing understanding of the nature of cancer development and behavior, cancer is becoming a chronic disease that a growing number of patients can live with for many years,” said Dr. Sledge. “The studies released today are the latest examples of progress against the disease, from new personalized treatments, to new approaches to screening and prevention.”
The study results from a phase II clinical trial involving maintenance therapy with the PARP (poly (ADP-ribose) polymerase) inhibitor olaparib were highlighted today in the ASCO press briefing, as summarized below.
Randomized Study Shows that Maintenance Therapy With PARP Inhibitors Could Play Important Role in Treatment of Recurrent Ovarian Cancer
A phase II randomized trial showed that maintenance treatment with the oral PARP inhibitor drug olaparib (AZD2281) improved progression-free survival by about four months in women with the most common type of relapsed ovarian cancer. This is the first randomized trial to demonstrate a benefit for maintenance therapy for recurrent ovarian cancer, and the first randomized trial in ovarian cancer of a PARP inhibitor– a novel class of molecularly targeted drugs.
The results of this study, if confirmed in larger trials, could lead to a new treatment approach for recurrent ovarian cancer in which drugs like olaparib are given over a long period of time to prevent recurrences or prolong remissions. This somewhat novel approach, called maintenance therapy, has already proven useful in lung cancer. Standard treatment for ovarian cancer includes platinum-based chemotherapy. After this regimen, patients are observed until recurrence, and then treated with another course of chemotherapy. While some tumors respond well to chemotherapy, the regimens are too toxic for patients to take continuously, and clinical trials have not shown any benefit for extended courses of chemotherapy.
“A well-tolerated antitumor agent that could be used for months or perhaps years as maintenance therapy after standard chemotherapy could be a big step forward and ultimately extend survival,” said lead author Jonathan A. Ledermann, M.D., principal investigator of the study and Professor of Medical Oncology at UCL Cancer Institute, University College London. “This study demonstrates proof of principle for the concept of maintenance therapy in ovarian cancer using a PARP inhibitor. Our progression-free survival difference was very impressive and better than we anticipated.”
The multicenter, international study randomized 265 women with high-grade serous ovarian cancer to either olaparib or placebo. Patients were enrolled in the trial within 8 weeks of having achieved either a complete or partial response to platinum-based treatment. PARP inhibitors have been shown to work better in patients whose tumors have responded to platinum.
In the study, the progression-free survival (PFS) – the amount of time during and after treatment in which the cancer does not return – was significantly longer in the group receiving olaparib than the placebo group, with a median of 8.4 months versus 4.8 months. At the time of data analysis, half the patients randomized to olaparib (68 patients) had not relapsed and were still receiving the drug, while only 16 percent (21 patients) remained on placebo – so overall survival data were not yet available for analysis.
Adverse events were more commonly reported in the group receiving olaparib than placebo, including nausea, fatigue, vomiting, and anemia, but the majority of these were not severe. Dose reductions to manage side effects were allowed in the study and were more prevalent in the olaparib group (23 percent) compared to the placebo group (7 percent).
Olaparib inhibits the enzyme poly (ADP-ribose) polymerase — abbreviated “PARP” — which is involved in DNA (deoxyribonucleic acid) repair. Up to half of women with high-grade serous ovarian cancer – the most common type of ovarian cancer – may have a DNA repair deficiency that makes them more susceptible to treatment with PARP inhibitors.
A number of PARP inhibitors are being studied in phase II and phase III clinical trials, as single agents and in combination with standard chemotherapies and radiation, in some types of breast and ovarian cancers believed to have DNA repair defects.
- ASCO Releases Studies From Upcoming Annual Meeting – Important Advances in Targeted Therapies, Screening, and Personalized Medicine – Randomized Study Shows that Maintenance Therapy & PARP Inhibitors Could Play Important Roles in Treatment of Relapsed Ovarian Cancer, Press Release, American Society of Clinical Oncology, May 18, 2011. [Adobe Reader PDF]
- Ledermann JA, Harter P, Gourley C, et. al. Phase II randomized placebo-controlled study of olaparib (AZD2281) in patients with platinum-sensitive relapsed serous ovarian cancer (PSR SOC). J Clin Oncol 29: 2011 (suppl; abstr 5003)(2011 ASCO Annual Meeting).
- A list of open ovarian cancer clinical trials involving PARP inhibitors.
- Long-Term Treatment with Olaparib May Help Treat Recurrent Ovarian Cancer, http://www.Cancer.net, May 18, 2011.
- 10 Exciting Ovarian Cancer Research Topics from 2010 — PARP Inhibitors & BRCA Gene-Mutated Ovarian Cancer (Topic #2 of 10) [Podcast Episode #2].
- PARP Inhibitor MK-4827 Shows Anti-Tumor Activity in First Human Clinical Study, November 17, 2010.
- PARP Inhibitor Olaparib Benefits Women With Inherited Ovarian Cancer Based Upon Platinum Drug Sensitivity, April 23, 2010.
- PARP Inhibitor MK4827 Active in Ovarian Cancer, MedPage Today, 2011 Society of Gynecologic Oncologists (SGO) Annual Meeting, March 23, 2011.
- PARP Inhibitors and Ovarian Cancer, Katherine Bell-McGuinn, M.D., Ph.D., Medical Oncologist, Memorial Sloan-Kettering Cancer Center, September 22, 2010.
- The role of homologous recombination in cancer & PARP inhibitors, Prof. Thomas Helleday, Gray Institute for Radiation Oncology, 2010 European Association For Cancer Research (EACR) Annual Mtg, ecancer.tv, August 18, 2010.
- PARP Inhibitors: Professor Hilary Calvert discusses his work on PARP inhibitor, Prof. Hilary Calvert, University College London, ecancer.tv, July 20, 2010.