Hypothesis Disproven in Randomized Phase 2 Trial

The NRG-GY023 trial, conducted by the National Cancer Institute and NRG Oncology, evaluated 153 patients with platinum-resistant ovarian, fallopian tube, or primary peritoneal cancer who had prior bevacizumab treatment. Patients were randomized 1:2:2:2 to standard chemotherapy, durvalumab/olaparib/cediranib triple therapy, durvalumab/cediranib, or olaparib/cediranib. As of September 9, 2024, the median progression-free survival (PFS) for the triple therapy arm was 2.9 months, compared to 3.4 months for the standard arm, with a hazard ratio of 1.003 and a 95% confidence interval of 0.56-1.80. Due to the hazard ratio for all experimental arms exceeding the pre-specified futility threshold of 0.87 in the interim analysis, enrollment was stopped on February 1, 2023.

Combination of Three Mechanisms Fails to Overcome Treatment Resistance

AstraZeneca's Imfinzi (durvalumab) is a PD-L1 inhibitor, and AstraZeneca and Merck's Lynparza (olaparib) is a PARP1/PARP2 inhibitor. Cediranib (AZD2171), an investigational drug without a marketed brand, inhibits VEGFR1, VEGFR2, and VEGFR3 tyrosine kinases, thereby blocking tumor angiogenesis. The objective response rate (ORR) for the triple therapy was 15.9%, higher than the 4.3% for the standard arm, but the median overall survival (OS) was 8.3 months and 7.5 months, respectively, with a small separation. The finding that increased response rates did not translate into durable disease control suggests that non-selective combination therapy alone is insufficient to overcome the angiogenesis, DNA repair, and immune evasion resistance mechanisms developed after bevacizumab exposure.

Approved Therapies Raise the Competitive Bar

The standard arm consisted of weekly paclitaxel, topotecan, or pegylated liposomal doxorubicin, as selected by the investigator; all three combinations were discontinued in Phase 2. AbbVie's Elahere (mirvetuximab soravtansine-gynx), a FRα-targeting antibody-drug conjugate, received accelerated approval from the FDA on November 14, 2022, and full approval on March 22, 2024, and was also approved by the EMA on November 14, 2024. The FDA approved Merck's PD-1 inhibitor, Keytruda (pembrolizumab), in combination with paclitaxel for patients with PD-L1 CPS ≥1 on February 10, 2026. Subsequently, on March 25, 2026, the combination of Corcept Therapeutics' Lifyorli (relacorilant) and nab-paclitaxel was approved for patients with prior bevacizumab treatment, making it a more direct competitive option than NRG-GY023.

Commercial Impact: Reduced Expansion Potential Compared to Existing Sales

Lynparza received accelerated approval from the FDA on December 19, 2014, for BRCA-mutated advanced ovarian cancer and secured approval for recurrent ovarian cancer maintenance therapy on August 17, 2017, and Imfinzi received its first FDA approval on May 1, 2017. Therefore, this failure undermines the expansion potential of these two products beyond their existing approved indications and the registrability of cediranib. The ovarian cancer treatment market in the seven major markets is projected to grow from USD 3.012 billion in 2025 to USD 5.703 billion in 2034, but market share is shifting towards approved therapies that select patients based on FRα, PD-L1, and treatment history, rather than non-selective multi-mechanism combinations. This strengthens the rationale for shifting research and development capital towards antibody-drug conjugates and the validation of complex biomarkers that explain resistance mechanisms, rather than simply expanding combination therapies.