Significance Of PIK3CA Mutations Research Articles

Abstract 485: Exon 9 mutation of PIK3CA associated with poor survival in patients with Epstein-Barr virus-associated gastric cancer

Abstract PIK3CA would seem to play an important role in the prognosis of gastric cancer (GC), very few studies have reported on the clinical implications and prognostic effects of these mutations in patients with Epstein-Barr virus-associated gastric cancer (EBVaGC). This study attempted to identify the prognostic significance of PIK3CA mutations in a large number of EBVaGC patients and the relationship of these mutations to the clinicopathologic parameters associated with prognosis. After reviewing 1318 consecutive cases of surgically resected at our institution between January 2011 and November 2014, 120 patients were identified as EBV-positive using EBV-encoded RNA in situ hybridization. Among the 120 patients, 8 patients were excluded due to insufficient or unavailable material (6 patients) and technical issues (2 patients). The related medical files and pathologic reports were all reviewed to identify the clinical and demographic characteristics. PIK3CA mutations were identified in formalin-fixed and paraffin-embedded surgical specimens from 112 EBVaGC patients with available tumor tissue sample. A real-time polymerase chain reaction was used to evaluate hot-spot mutations of exons 1, 4, 7, 9, and 20 of PIK3CA. The frequency of PIK3CA mutations was 25.0% (n=28), and among the 28 patients harboring a PIK3CA mutation, most of the mutations were identified in exon 9 (n=21, 75%). The presence of PIK3CA mutation was also correlated with a higher T category (P<0.001) and N category (P<0.001), as well as the presence of perinueral invasion (P<0.001) and venous invasion (P<0.001). In a univariate analysis, PIK3CA mutation showed no association with overall survival (OS) (P=0.184) or disease-free survival (DFS) (P=0.150). The patients harboring exon 9 PIK3CA mutations did exhibit a significantly shorter OS(P=0.023) and DFS(P=0.013) than the patients lacking an exon 9 PIK3CA mutation, yet without statistical significance in the multivariate analysis. Notably, the exon 9 E542K mutation of PIK3CA was associated with the worst DFS (P=0.011). Plus, the PIK3CA-mutant tumors were not related to such immune-related factors as intratumoral (iTu) tumor-infiltrating lymphocytes (TILs), stromal (str) TILs, iTu-PD-L1, and str-PD-L1 (all P > 0.05). The PIK3CAmutations harbored in exon 9 were also strongly related to clinicopathologic parameters associated with an unfavorable prognosis. Although the exon 9 PIK3CA mutations were not identified as an independently robust prognostic factor, they could play an important role in carcinogenesis and tumor aggressiveness in EBVaGC. Consequently, these findings support the theory that exon 9 PIK3CA mutations can be a prognostic indicator for predicting patients’ outcomes and a rationale for therapeutic targeting in EBVaGC. Citation Format: Dongwon Baek, Jong Gwang Kim, Jin Ho Baek, Byung Woog Kang, Soo Jung Lee, Yee Soo Chae, Hee Jeong Cho. Exon 9 mutation of PIK3CA associated with poor survival in patients with Epstein-Barr virus-associated gastric cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 485.

PIK3CA mutation as a prognostic factor in HPV-associated oropharynx cancer.

6011 Background: PIK3CA is the most frequently mutated gene in HPV-associated oropharyngeal SCC (OPSCC), with a prevalence of 20-30%. While PIK3CA mutations have been associated with adverse outcomes in cervical cancer, their prognostic significance in HPV-associated OPSCC remains unknown. We sought to elucidate the significance of PIK3CA mutations in a prospective cohort of HPV-associated OPSCC patients treated with definitive chemoradiation (CRT). Methods: Seventy-eight patients with HPV-associated OPSCC were prospectively enrolled on three protocols: LCCC 1121 (NCT03161821) or two phase II clinical trials of de-intensified CRT (NCT02281955 / NCT03077243). De-intensified regimen was 60 Gy IMRT with concurrent cisplatin (30mg/m2). Next-generation sequencing of tumor samples was performed using a targeted panel-based assay (UNCSeq), including over 200 genes. We estimated disease-free survival (DFS) using the Kaplan-Meier method and compared treatment groups with two-sided log-rank test (Medcalc). Results: Sequencing was performed in 78 patients with a median follow-up of 24 months. Seventy-five patients received 60Gy; three patients received 70Gy. Ten patients had disease recurrence (2 regional only, 5 distant only, 3 regional and distant). Thirty-eight of 78 patients had at least one mutation identified (17 PIK3CA, 4 PTEN, 3 KRAS, 3 FBXW7, 3 FGFR3, 2 TP53, 2 prothrombin 20210, 1 NRAS, 1 BRCA1, 1 factor V Leiden, 1 FLT3, 1 RAD50, 1 PIK3R1). The most common site of PIK3CA mutation was the helical domain (E545K – 8/17, E542K – 2/17). Despite similar T/N staging and tobacco pack years, patients with WT-PIK3CA had significantly higher DFS (93%) compared with 65% for patients with PIK3CA mutations (p = 0.0009). Patients with mutations other than PIK3CA also had improved DFS relative to those with PIK3CA mutations (96% vs. 65%; p = 0.0147). Conclusions: PIK3CA mutation is associated with worse DFS in a prospective cohort of newly diagnosed HPV-associated OPSCC patients treated with definitive CRT. These findings suggest that patients with PIK3CA mutations may not be suitable for de-intensified therapy and investigation of novel treatment strategies may be appropriate.

Prognostic and clinical impact of PIK3CA mutation in gastric cancer: pyrosequencing technology and literature review.

BackgroundPhosphatidylinositol-4,5-bisphosphate 3-kinase, catalytic subunit alpha (PIK3CA) mutations that activate the PI3K/AKT signaling pathway have been observed in several types of carcinoma and have been associated with patient prognosis. However, the significance of PIK3CA mutations in gastric cancer remains unclear. This retrospective study investigated the relationship between PIK3CA mutations and clinical outcomes in patients with gastric cancer. Additionally, we reviewed the rate of PIK3CA mutations in gastric cancer and the association between PIK3CA mutations and prognosis in human cancers.MethodsThe study included 208 patients with gastric cancer who underwent surgical resection at Kumamoto University Hospital, Japan, between January 2001 and August 2010. Mutations in PIK3CA exons 9 and 20 were quantified by pyrosequencing assays.ResultsPIK3CA mutations were detected in 25 (12 %) of the 208 patients. Ten patients had c.1634A > G (p.E545G), 10 had c.1624G > A (p.E542K), 13 had c.1633G > A (p.E545K), nine had c.3139C > T (p.H1047R), and 1 had c.3140A > G (p.H1047Y) mutations. PIK3CA mutations were not significantly associated with any clinical, epidemiologic, or pathologic characteristic. Kaplan–Meier analysis showed no significant differences in disease-free survival (log rank P = 0.84) and overall survival (log rank P = 0.74) between patients with and without PIK3CA mutations.ConclusionsMutations in PIK3CA did not correlate with prognosis in patients with gastric cancer, providing additional evidence for the lack of relationship between the two.

Defining the Prognostic and Predictive Role of PIK3CA Mutations: Sifting Through the Conflicting Data

PIK3CA is one of the most commonly mutated oncogenes in breast cancer, albeit at variable distribution among the different biological subtypes. Overall, it appears that PIK3CA mutations are most likely found in tumors with less aggressive characteristics, especially estrogen receptor (ER)-positive, luminal A tumors. Studies assessing its prognostic or predictive role have reported conflicting data, in part due to different methodologies used for detection and small sample sizes. The majority of reports used retrospective data from clinical trials thus could not exclude the effect of treatment heterogeneity when evaluating prognostic factors, and analysis was not subtype specific. Since breast cancer subtypes differ in terms of biology, treatment, and outcomes, it is critical that the effects of PIK3CA mutations on pathophysiology and therapy responsiveness are analyzed independently in each subtype. This short review discusses these issues and the significance of PIK3CA mutations in relation to the expression of HER2 and hormone receptors.

Significance of PIK3CA Mutations in Patients with Early Breast Cancer Treated with Adjuvant Chemotherapy: A Hellenic Cooperative Oncology Group (HeCOG) Study

BackgroundThe PI3K-AKT pathway is frequently activated in breast cancer. PIK3CA mutations are most frequently found in the helical (exon 9) and kinase (exon 20) domains of this protein. The aim of the present study was to examine the role of different types of PIK3CA mutations in combination with molecular biomarkers related to PI3K-AKT signaling in patients with early breast cancer.MethodsTumor tissue samples from 1008 early breast cancer patients treated with adjuvant chemotherapy in two similar randomized trials of HeCOG were examined. Tumors were subtyped with immunohistochemistry (IHC) and FISH for ER, PgR, Ki67, HER2 and androgen receptor (AR). PIK3CA mutations were analyzed by Sanger sequencing (exon 20) and qPCR (exon 9) (Sanger/qPCR mutations). In 610 cases, next generation sequencing (NGS) PIK3CA mutation data were also available. PIK3CA mutations and PTEN protein expression (IHC) were analyzed in luminal tumors (ER and/or PgR positive), molecular apocrine carcinomas (MAC; ER/PgR negative / AR positive) and hormone receptor (ER/PgR/AR) negative tumors.ResultsPIK3CA mutations were detected in 235/1008 tumors (23%) with Sanger/qPCR and in 149/610 tumors (24%) with NGS. Concordance between the two methods was good with a Kappa coefficient of 0.76 (95% CI 0.69–0.82). Lobular histology, low tumor grade and luminal A tumors were associated with helical domain mutations (PIK3CAhel), while luminal B with kinase domain mutations (PIK3CAkin). The overall incidence of PIK3CA mutations was higher in luminal as compared to MAC and hormone receptor negative tumors (p = 0.004). Disease-free and overall survival did not significantly differ with respect to PIK3CA mutation presence and type. However, a statistically significant interaction between PIK3CA mutation status and PTEN low protein expression with regard to prognosis was identified.ConclusionsThe present study did not show any prognostic significance of specific PIK3CA mutations in a large group of predominantly lymph-node positive breast cancer women treated with adjuvant chemotherapy. Further analyses in larger cohorts are warranted to investigate possible differential effect of distinct PIK3CA mutations in small subgroups of patients.

1976 Significance of PIK3CA mutations in patients with early breast cancer treated with adjuvant chemotherapy: A Hellenic Cooperative Oncology Group (HeCOG) study

1976 Significance of PIK3CA mutations in patients with early breast cancer treated with adjuvant chemotherapy: A Hellenic Cooperative Oncology Group (HeCOG) study

Reverse-Phase Protein Array Profiling of Oropharyngeal Cancer and Significance of PIK3CA Mutations in HPV-Associated Head and Neck Cancer

Human papilloma virus (HPV)-associated (HPV+) oropharyngeal squamous cell carcinomas (OPSCC) have different molecular and biologic characteristics and clinical behavior compared with HPV-negative (HPV-) OPSCC. PIK3CA mutations are more common in HPV(+) OPSCC. To define molecular differences and tumor subsets, protein expression and phosphorylation were compared between HPV(+) and HPV(-) OPSCC and between tumors with and without PIK3CA mutations. Expression of 137 total and phosphorylated proteins was evaluated by reverse-phase protein array in 29 HPV(+) and 13 HPV(-) prospectively collected OPSCCs. Forty-seven OPSCCs were tested for hotspot-activating mutations in PIK3CA and AKT. Activation of PIK3CA downstream targets and sensitivity to pathway inhibitors were determined in HPV(+) head and neck cancer cells overexpressing wild-type or mutant PIK3CA. Analyses revealed 41 differentially expressed proteins between HPV(+) and HPV(-) OPSCC categorized into functional groups: DNA repair, cell cycle, apoptosis, phosphoinositide 3-kinase (PI3K)/AKT/mTOR, and receptor kinase pathways. All queried DNA repair proteins were significantly upregulated in HPV(+) samples. A total of 8 of 33 HPV(+) and 0 of 14 HPV(-) tumors contained activating PIK3CA mutations. Despite all activating PIK3CA mutations occurring in HPV(+) samples, HPV(+) tumors had lower mean levels of activated AKT and downstream AKT target phosphorylation. Ectopic expression of mutant PIK3CA in HPV(+) cells increased mTOR, but not AKT activity. HPV E6/E7 overexpression inhibited AKT phosphorylation in HPV-negative cells. Mutant PIK3CA overexpressing cells were more sensitive to a dual PI3K/mTOR inhibitor compared with an AKT inhibitor. Protein expression analyses suggest that HPV(+) and HPV(-) OPSCC differentially activate DNA repair, cell cycle, apoptosis, PI3K/AKT/mTOR, and receptor kinase pathways. PIK3CA mutations are more common in HPV(+) OPSCC and are associated with activation of mTOR, but not AKT. These data suggest that inhibitors for mTOR may have activity against HPV(+) PIK3CA mutant oropharyngeal cancers.

Mutant PIK3CA Is Detected in Both Pre-Invasive and Recurrent Breast Cancer.

Abstract BackgroundWe identified somatic PIK3CA mutations in 32.5% of 590 primary invasive breast cancers (BC) (manuscript in press: Clinical Cancer Research). Detected by massARRAY genotyping, PIK3CA mutations significantly associate with favorable clinicopathologic features and improved clinical outcome, including overall and breast cancer-specific survival. Given the strong association between PIK3CA mutations and hormone receptor (HR) positivity, one hypothesis is that PIK3CA mutations 'drive' HR positive BC and will be detected in pre-invasive breast tumors. As PIK3CA mutations offer a protective effect in BC, it has not been determined whether PIK3CA mutations are selected for in disease progression or whether additional collaborating mutations are required.MethodsTo determine the concordance of PIK3CA mutations and assess the acquisition of additional oncogene mutations, available matched tissue samples, from the previous database, were procured and underwent massARRAY genotyping (n = 83). Two mm cores were macro-dissected from matched formalin-fixed, paraffin embedded tissue, including normal breast tissue, benign lymph nodes (LN), ductal carcinoma-in-situ (DCIS), regional LN metastases (mets), and distant mets. MassARRAY (Sequenom) genotyping was performed on native DNA to identify rare and hotspot PIK3CA mutations, as well as AKT1 (E17K), RAS, and RET mutations.ResultsConcordance of PIK3CA mutations is noted between primary BC and DCIS, except for one rare PIK3CA mutation (Q546R) not detected in DCIS (4/5). No PIK3CA mutations are detected in normal breast tissue (0/8) or benign LN (0/6). Rare and hotspot PIK3CA mutations in primary BC are detected in 87.5% (7/8) matched regional LN met and 80 % (4/5) distant mets. For the patient with the disconcordant regional LN met, the rare PIK3CA mutation (H1047L) identified in primary BC is also present in the distant met site. Notably, for the single disconcordant PIK3CA met site, a rare PIK3CA mutation (E545A) is detected in a primary tumor, regional LN met, and bone met and is absent in a second bone met, in which a KRAS (G12C) mutation has been identified. One concomitant hotspot PIK3CA (E542K)/KRAS (G12C) mutation is present in both primary BC and paired DCIS. Complete concordance of AKT1 (E17K) mutations has been identified between in DCIS, primary BC, regional LN met, and distant mets (n=4).ConclusionsWe recently defined the positive prognostic significance of PIK3CA mutations in breast cancer. PIK3CA and AKT1 (E17K) mutations are early events in breast cancer, occurring in pre-invasive tumors. Despite the protective effect of PIK3CA mutations on clinical outcome, they persist and are selected for in disease progression, as they are detected in regional LN and distant mets. Complete concordance is identified between hotspot PIK3CA mutated primary BC and matched tumors samples, suggesting that PIK3CA mutations with higher oncogenic potency are maintained in tumor progression. These findings support that targeting the PI3K pathway may assist in tailoring therapy to appropriate patient populations. We are expanding matched tissue collection from a separate patient cohort to further assess genomic and functional genomic change with disease progression. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 5164.

Use of multiplex mutation genotyping to identify novel and protective mutations in breast cancer

11004 Background: We recently analyzed 590 primary invasive breast tumors for PIK3CA mutations by multiplex massARRAY genotyping. We identified a 32.5% PIK3CA mutation rate (manuscript submitted). Associations between PIK3CA mutation status and favorable pathology, such as lower grade tumors, lymph node negativity and hormone receptor (HR) positivity, were observed. Multiplex analysis allows the rapid assessment of mutations not commonly described in breast cancer. To identify activated pathways that may serve as predictive biomarkers, tissue microarrays (TMA) underwent immunohistochemical (IHC) analysis. Methods: 590 archival formalin-fixed paraffin embedded (FFPE) tumors > 1 cm were used to ensure adequate tissue procurement for mutation detection and TMA construction. MassARRAY (Sequenom) genotyping was performed on native DNA to identify PIK3CA, RAS, RET, and other known mutations. IHC staining of the TMAs included assessment of steroid nuclear receptors, HER2 expression, Akt pathway activation (including pAKT, p70S6K, eIF4E), and PTEN. Stained TMAs underwent digital quantitative image analysis and scoring (Aperio, Vista, CA). The Kaplan-Meier method and Cox models were used in univariate and multivariate analysis for associations of mutation status and clinicopathologic features on overall survival (OS) and breast cancer-specific survival (BCSS). Results: Compared to wild-type, PIK3CA mutated tumors (median f/u: 12.8 years) demonstrate a significant improvement in OS (p=0.03) and BCSS (p=0.004). For patients with any PIK3CA mutation, the improvement in BCSS is maintained in HR positive and ER negative subgroups. In addition to PIK3CA mutations, RAS and RET mutations are identified in a small proportion of breast tumors. Additional analysis to evaluate the association of mutation status and biomarker data derived from the TMA analysis will be performed for meeting presentation. Conclusions: We have recently defined the positive prognostic significance of PIK3CA mutations in breast cancer. RAS mutations are confirmed to occur rarely in breast cancer. The finding of RET mutations in breast cancer is novel. Future tumor biomarker identification directed towards predictive measurement will assist in tailoring therapy to appropriate patient populations. No significant financial relationships to disclose.