PIK3CA amplification associates with resistance to chemotherapy in ovarian cancer patients.

PI3K/AKT signalling pathway controls important cellular processes such as the cell proliferation and apoptosis. PIK3CA gene encoding a catalytic subunit of the PI3K is mutated and/or amplified in various neoplasms, including ovarian cancer. We aimed to evaluate PIK3CA alterations and their clinical importance in ovarian cancer patients. Molecular analysis was performed on 117 ovarian carcinomas with the use of qPCR, SSCP and sequencing. In a group of 98 patients with complete clinical data, 62 patients were treated with standard taxane-platinum regimens and 36 patients with platinum-cyclophosphamide regimens. A multivariate analysis was performed by the Cox's and logistic regression models. PIK3CA mutations occurred in 5/117 (4.3%) carcinomas, exclusively in the endometrioid and clear cell types (p = 0.0002); they were also associated with low FIGO stage (p = 0.0003), low tumor grade (p = 0.045) and early patient's age at diagnosis (p = 0.0005). The PIK3CA amplification (predominantly a low-level) was found in 28/117 (24%) ovarian carcinomas. It was more frequent in TP53 mutant tumors (p = 0.012) and tended to associate with high pAKT expression (p = 0.061). The PIK3CA amplification strongly diminished odds of complete remission (OR = 0.25, p = 0.033) and platinum sensitive response (PS, OR = 0.12, p = 0.004) in the taxane-platinum treated patients. The odds of PS were also much lower in all patients with the PIK3CA amplification evaluated together, regardless of the treatment applied (OR = 0.18, p = 0.001). Our results suggest that PIK3CA amplification may be a marker predicting ovarian cancer response to chemotherapy.

TP53, BCL-2 and BAX analysis in 199 ovarian cancer patients treated with taxane-platinum regimens.

OBJECTIVE: In cell line studies, BCL-2 and BAX proteins interfere with cancer response to taxanes. This issue has not received much attention with regard to taxane-platinum (TP)-treated ovarian cancer patients. METHODS: We evaluated prognostic/predictive significance of BCL-2 and BAX with regard to TP53 status. Immunohistochemical analysis was performed on 199 ovarian carcinomas FIGO stage IIB-IV treated with TP; the results were analyzed by the Cox and logistic regression models. RESULTS: Clinicopathological parameters (residual tumor size, FIGO stage and/or tumor grade, but not patient's age) were the only or the strongest predictors of patient's outcome. Platinum highly sensitive response showed a positive association with TP53 accumulation (p=0.045). As in our previously published analysis on platinum-cyclophosphamide-treated group, complete remission showed a borderline negative (paradoxic) association with high BAX expression in the whole group (p=0.058) and with BCL-2 expression in the TP53(-) group (p=0.058). CONCLUSION: Our results suggest that TP53, BCL-2 and BAX proteins carry some predictive potential in taxane-platinum-treated ovarian cancer patients, auxiliary to clinicopathological factors. We have confirmed on another patient group that clinical importance of BCL-2 may depend on TP53 status.

TP53 status and taxane-platinum versus platinum-based therapy in ovarian cancer patients: a non-randomized retrospective study.

BACKGROUND: Taxane-platinum therapy (TP) has replaced platinum-based therapy (PC or PAC, DNA damaging chemotherapy) in the postoperative treatment of ovarian cancer patients; however, it is not always effective. TP53 protein plays a differential role in response to DNA-damaging agents and taxanes. We sought to define profiles of patients who benefit the most from TP and also of those who can be treated with PC. METHODS: We compared the effectiveness of PC/PAC (n = 253) and TP (n = 199) with respect to tumor TP53 accumulation in ovarian cancer patients with FIGO stage IIB-IV disease; this was a non-randomized retrospective study. Immunohistochemical analysis was performed on 452 archival tumors; univariate and multivariate analysis by the Cox's and logistic regression models was performed in all patients and in subgroups with [TP53(+)] and without TP53 accumulation [TP53(-)]. RESULTS: The advantage of taxane-platinum therapy over platinum-based therapy was seen in the TP53(+), and not in the TP53(-) group. In the TP53(+) group taxane-platinum therapy enhanced the probability of complete remission (p = .018), platinum sensitivity (p = .014), platinum highly sensitive response (p = .038) and longer survival (OS, p = .008). Poor tumor differentiation diminished the advantage from taxane-platinum therapy in the TP53(+) group. In the TP53(-) group PC/PAC was at least equally efficient as taxane-platinum therapy and it enhanced the chance of platinum highly sensitive response (p = .010). However, in the TP53(-) group taxane-platinum therapy possibly diminished the risk of death in patients over 53 yrs (p = .077). Among factors that positively interacted with taxane-platinum therapy in some analyses were endometrioid and clear cell type, FIGO III stage, bulky residual tumor, more advanced age of patient and moderate tumor differentiation. CONCLUSION: Our results suggest that taxane-platinum therapy is particularly justified in patients with TP53(+) tumors or older than 53 years. In the group of patients < or =53 yrs and with TP53(-) tumors platinum-based therapy is possibly equally efficient. We provide hints for planning randomized trials to verify these observations.