Turning the Tide Against Ovarian Cancer

May 8th marks World Ovarian Cancer Day – a moment to raise awareness of one of the most lethal gynecologic disorders. Ovarian cancer often goes undetected until it has reached an advanced stage, with nearly 70% of ovarian cancer patients diagnosed at an advanced stage due to subtle and easily overlooked early symptoms.

In recent years, advances in precision oncology, particularly therapies targeting tumor DNA repair mechanisms, have offered new hope. PARP inhibitors stand out among these therapies for expanding treatment options to a wider population of ovarian cancer patients. As research continues, such innovations bring new hope to those facing this challenging disease.

Ovarian cancer remains a significant global health challenge. According to the International Agency for Research on Cancer (IARC), over 320,000 new cases were diagnosed globally in 2022, with nearly 207,000 deaths attributed to the disease. 

Historically, treatment has relied on surgical tumor removal followed by platinum-based chemotherapy in combination with taxanes. While approximately 80% of patients achieve complete remission after first-line therapy, 60–80% relapse within 18 months, often due to chemotherapy resistance. Second-line platinum chemotherapy can offer temporary control, but 85% of patients still experience disease progression within two years. These challenges underscore the critical need for maintenance therapies that can extend remission and delay progression.

The 21st century ushered in an era of targeted cancer therapies. The development of PARP inhibitors was a major breakthrough, introducing a new class of drugs rooted in a concept known as synthetic lethality.

This concept dates back to a 1922 discovery, where researchers observed that while two individual gene mutations were harmless on their own, their combination proved lethal. This principle later informed cancer research: tumor cells with specific mutations could be selectively targeted by inhibiting a second, compensatory DNA repair pathway.

In normal cells, PARP proteins repair single-strand DNA breaks, while BRCA proteins repair double-strand breaks. In BRCA-deficient cancer cells, such as those found in some ovarian cancers, further blocking of PARP activity causes DNA damage to accumulate to a lethal threshold—effectively killing cancer cells while sparing healthy ones. This insight laid the groundwork for the development of PARP inhibitors as targeted cancer therapies. 

The first PARP inhibitor, olaparib (Lynparza), was approved in 2014 for patients with BRCA-mutated advanced ovarian cancer. Following its success, several other PARP inhibitors entered clinical development. 

For example, TESARO’s niraparib delivered particularly compelling results in a large Phase 3 clinical trial. In patients with BRCA mutations, niraparib extended median progression-free survival (PFS) to 21 months compared to 5.5 months with placebo. Even in patient group without BRCA mutations, niraparib still showed a median PFS of 9.3 months compared to 3.9 months. 

These results led the U.S. FDA to grant Priority Review in late 2016, and niraparib was approved just three months later as a maintenance therapy for women with recurrent epithelial ovarian, fallopian tube, or primary peritoneal cancer who responded to platinum-based chemotherapy. 

The journey of PARP inhibitors—from a century-old genetic insight to a life-extending therapy for thousands of women—is a testament to the power of science, perseverance, and global collaboration. 

As we observe World Ovarian Cancer Day, we are reminded of both the immense challenge of this disease and the meaningful progress that innovative therapies can deliver. Together, through partnerships across borders and disciplines, we can continue to advance treatments and deliver hope to women around the world.