Myriad Genetics Receives the US FDA Approval for MyChoice CDx Test as a Companion Diagnostic for GSK’s Zejula

Why It Matters

The diagnostic enables clinicians to match Zejula to patients most likely to respond, improving outcomes while supporting the broader shift toward biomarker‑driven cancer care.

Key Takeaways

• FDA clears MyChoice CDx for HRD detection in ovarian cancer.
• Test guides Zejula use in patients with advanced disease.
• NGS evaluates BRCA1/2 mutations and genomic instability score.
• HRD+ status predicts better response to PARP inhibitor therapy.
• Companion diagnostic aligns with GSK’s precision oncology strategy.

Pulse Analysis

Companion diagnostics have become a linchpin of modern oncology, translating molecular insights into actionable treatment pathways. The FDA’s endorsement of MyChoice CDx underscores the regulatory momentum behind assays that can reliably stratify patients based on homologous recombination deficiency (HRD). By integrating comprehensive BRCA1/2 sequencing with a tumor genomic instability score, the test offers a nuanced view of DNA repair defects, a critical factor for selecting PARP inhibitors like Zejula.

The clinical foundation for MyChoice CDx rests on the PRIMA trial, which demonstrated that HRD‑positive ovarian cancer patients experienced markedly longer progression‑free survival when treated with niraparib after platinum‑based chemotherapy. This data not only validates the assay’s predictive power but also highlights the importance of next‑generation sequencing platforms that can capture large‑scale genomic rearrangements alongside point mutations. As oncologists seek to personalize therapy, the ability to quantify loss of heterozygosity, telomeric allelic imbalance, and large‑scale state transitions provides a robust biomarker that can be integrated into routine pathology workflows.

From a market perspective, the approval strengthens Myriad Genetics’ position in the competitive companion‑diagnostic arena and reinforces GSK’s commitment to precision medicine. Healthcare systems are likely to adopt the test to meet payer requirements for biomarker‑guided therapy, potentially expanding the eligible patient pool for Zejula. Moreover, the move may spur further collaborations between diagnostic innovators and pharma companies, accelerating the development of tailored treatment regimens across a range of solid tumors.