The combination of cediranib and olaparib improved progression-free survival in patients with platinum-resistant ovarian cancer, although the difference from chemotherapy did not achieve statistical significance.
Nicoletta Colombo, MD
The combination of cediranib and olaparib (Lynparza) improved progression-free survival (PFS) in patients with platinum-resistant ovarian cancer (PROC), although the difference from chemotherapy did not achieve statistical significance, a randomized trial showed.1
Continuous treatment with the VEGF inhibitor cediranib and the PARP inhibitor olaparib led to a median PFS of 5.7 months as compared with 3.1 months with weekly paclitaxel. The difference represented a 24% decrease in the hazard for disease progression or death but did not significantly distinguish itself from paclitaxel (HR, 0.76; 90% CI, 0.49-1.17; P = .29). The combination appeared even more active in patients with germline (g) BRCA wild-type tumors, resulting in a 37% reduction in the hazard ratio versus paclitaxel.
Intermittent therapy with the combination led to a median PFS of 3.8 months, Nicoletta Colombo, MD, of the European Oncology Institute in Milan, reported at the 2019 ESMO Congress.
“The BAROCCO trial included a difficult-to-treat population with a high unmet need: 59% of the patients had received 3 or more lines of therapy and their median platinum-free interval was less than 3 months,” said Colombo. “Although not statistically significant, the continuous administration [of the combination] shows a promising trend for improved progression-free survival, particularly in the germline BRCA wild-type population.
“The continuous administration of cediranib and olaparib is active in platinum-resistant ovarian cancer patients, with a clinical benefit observed in 85% of patients. The regimen was well tolerated with few severe side effects,” added Colombo.
Despite recent advances in the treatment of platinum-sensitive ovarian cancer, PROC continues to represent a high unmet need. The disease is associated with a median PFS of 3 to 4 months with weekly paclitaxel, which is the most effective chemotherapy regimen, said Colombo.
The FDA approved single-agent olaparib for relapsed gBRCA-mutant ovarian cancer, but limited data exist regarding the activity of PARP inhibitors in BRCA wild-type PROC.
Evidence does exist for PARP inhibitor activity beyond gBRCA-mutant disease when combined with an angiogenesis inhibitor. Cediranib/olaparib led to a fourfold increase in median PFS compared to olaparib monotherapy in patients with gBRCA wild-type ovarian cancer.2 Bevacizumab (Avastin) and niraparib (Zejula) more than doubled median PFS in gBRCA wild-type ovarian cancer as compared with niraparib alone.3
“The combination of cediranib and olaparib may have a synergistic effect,” said Colombo. “Molecular pharmacology studies suggest that cediranib induces downregulation of some genes that are involved in homologous recombination, thus producing a sort of functional BRCAness that favors the selective activity of the PARP inhibitior.”
With that background, investigators at multiple centers in Italy performed a randomized phase II trial comparing weekly paclitaxel with 2 different cediranib/olaparib regimens. All patients received olaparib at 300 mg twice daily, as well as cediranib at 20 mg daily. However, one group of patients received cediranib 7 days a week (continuous) and a second group received the VEGF inhibitor 5 days a week (intermittent). Patients randomized to paclitaxel received 80 mg/m2 weekly.
Investigators assumed a median PFS of 3.4 months with paclitaxel and projected that the combination would reduce the hazard ratio by 49% (3.3-month improvement).
The trial included 123 patients, randomized 1:1:1 to the 3 treatment arms. The groups were balanced with respect to distribution of baseline characteristics. Data were stratified by BRCA status (89% wild-type or unknown), prior antiangiogenic therapy (53%), and prior lines of chemotherapy (three or more, 59% ).
Colombo said 12 patients allocated to paclitaxel withdrew from the study following randomization, leaving 29 for data analysis. Subsequently, 95% to 100% of patients in all 3 groups dropped out, primarily because of disease progression (80%-90%). Three patients in the paclitaxel group withdrew because of adverse events, as did 3 in the continuous-therapy arm and 1 in the intermittent arm.
The 24% relative difference in the PFS hazard between the continuous and paclitaxel arms included a 28.2% absolute difference in favor of the combination at 2 months and 15.7% difference at 4 months. Thereafter, the survival curves started to converge, but continuous combination therapy maintained an advantage throughout. The comparison of paclitaxel versus intermittent combination therapy produced a hazard ratio of 1.08 (P = .76).
A subgroup analysis of PFS showed that continuous treatment with the combination was particularly active in patients with no more than 2 prior lines of chemotherapy (HR, 0.47) and those with no prior antiangiogenic therapy (HR, 0.58), as well as the patients with gBRCA wild-type or unknown status (HR, 0.63).
Analysis of objective response favored paclitaxel (33.3%) over the continuous (17.9%) and intermittent (11.4%) combination arms, whereas stable disease occurred two to three times as often with continuous (66.7%) and intermittent (51.4%) combination therapy (20.8% for paclitaxel).
The proportion of patients with progressive disease as best response was 45.8% in the paclitaxel group, 15.4% with the continuous combination arm, and 37.1% with the intermittent combination arm.
Combination therapy (both arms) was associated with substantially more drug-related adverse events, including diarrhea (51%-58%), nausea (50%-51%), vomiting (37%-38%), fatigue (40%-46%), and hypertension (18%-29%). The most common grade ≥3 treatment-related adverse events associated with the combination were anemia (10%-13%), fatigue (10%), and hypertension (12%-13%).