Robert Zeillinger

GANNET53 Part II: A European Phase I/II Trial of the HSP90 Inhibitor Ganetespib in High-Grade Platinum-Resistant Ovarian Cancer—A Study of the GANNET53 Consortium

Abstract Purpose: Mutant p53 stabilized by heat shock protein 90 (HSP90) is a novel target in oncology. The open-label, randomized phase II GANNET53 trial is the first to evaluate the HSP90 inhibitor ganetespib (G) with paclitaxel (P) in platinum-resistant epithelial ovarian cancer (EUDRACT 2013-003868-31; EU FP7 #602602). Patients and Methods: Patients were randomized 2:1 to receive G + P or P alone until progression. Primary endpoints were progression-free survival (PFS) and PFS rate at 6 months. Exploratory endpoints were biomarkers based on p53 and HSP90. Results: A total of 133 patients were enrolled. The median PFS was 3.5 (G + P) and 5.3 months (P) (HR = 1.3; 95% confidence interval, 0.897–1.895; P = 0.16), and PFS rates at 6 months were 22% (G + P) and 33% (P). No significant differences were found in overall survival, objective response rate, and post-progression PFS between arms. The most frequent adverse events were diarrhea (79% vs. 26%), anemia (46% vs. 51%), nausea (41% vs. 40%), and peripheral neuropathy (36% vs. 47%). Serious adverse events were more common in G + P (39.5% vs. 23.3%). Gastrointestinal perforation was a new safety finding. Despite a high TP53 mutation frequency, HSP90–p53 complexes were detected in only 39.6% of the cases and were also detected stably during treatment. In vitro, no synergistic effects of G + P were observed, and mutant p53 depletion did not sensitize ovarian cancer cells to treatment. Conclusions: Although no major safety findings were observed, G + P did not lead to survival benefit. Our companion diagnostic program confirmed that G + P do not favorably cooperate in killing ovarian cancer cells.

Association of the Single Nucleotide Polymorphisms rs11556218, rs4778889, rs4072111, and rs1131445 of the Interleukin-16 Gene with Ovarian Cancer

Single nucleotide polymorphisms (SNPs) of the IL-16 gene have been reported to influence the risk of several cancers, but their role in ovarian cancer (OC) has not been studied. Using the restriction fragment length polymorphism (PCR-RFLP) method, we examined four IL-16 SNPs: rs11556218 (T > G), rs4778889 (T > C), rs4072111 (C > T), and rs1131445 (T > C) in blood samples from 413 women of Central European descent, including 200 OC patients and 213 healthy controls. Among the patients, 62% were postmenopausal, 84.5% were diagnosed in late stages (FIGO IIb-IV), and 73.5% had high-grade serous OC (HGSOC). Minor allele frequencies in controls were 9.2% for rs11556218 (G allele), 13.7% for rs4778889 (C allele), 10.4% for rs4072111 (T allele), and 32.3% for rs1131445 (C allele). We found significant associations of rs11556218 (G vs. T allele: OR 2.76, 95% CI 1.84–4.14, p < 0.0001) with elevated OC risk in the whole cohort (p < 0.001) and in both premenopausal (p < 0.001) and postmenopausal (p = 0.001) subgroups. These associations remained significant across heterozygote (p < 0.001), dominant (p < 0.001), and overdominant (p < 0.001) models. IL-16 rs4778889 was associated with OC risk predominantly in premenopausal women (p < 0.0001 in almost all models). In the whole cohort, the C allele was associated with OC risk (OR 1.54, CI 95% 1.06–2.23, p = 0.024), and the association of rs4778889 was significant in dominant (p = 0.019), overdominant (p = 0.033), and heterozygote (p = 0.027) models. Furthermore, rs4778889 was linked with HGSOC (p = 0.036) and endometriosis-related OC subtypes (p = 0.002). No significant associations were found for rs4072111 or rs1131445 (p = 0.81 or 0.47, respectively). In conclusion, rs11556218 and rs4778889 SNPs are associated with OC risk, especially in premenopausal women.

Amyloid-like p53 as prognostic biomarker in serous ovarian cancer—a study of the OVCAD consortium

TP53 is the most commonly mutated gene in cancer and has been shown to form amyloid-like aggregates, similar to key proteins in neurodegenerative diseases. Nonetheless, the clinical implications of p53 aggregation remain unclear. Here, we investigated the presence and clinical relevance of p53 aggregates in serous ovarian cancer (OC). Using the p53-Seprion-ELISA, p53 aggregates were detected in 46 out of 81 patients, with a detection rate of 84.3% in patients with missense mutations. High p53 aggregation was associated with prolonged progression-free survival. We found associations of overall survival with p53 aggregates, but they did not reach statistical significance. Interestingly, p53 aggregation was significantly associated with elevated levels of p53 autoantibodies and increased apoptosis, suggesting that high levels of p53 aggregates may trigger an immune response and/or exert a cytotoxic effect. To conclude, for the first time, we demonstrated that p53 aggregates are an independent prognostic marker in serous OC. P53-targeted therapies based on the amount of these aggregates may improve the patient's prognosis.