Abstract 3393
Background
Mutations in PIK3CA, an EGFR downstream effector, and the subsequent activation of AKT pathway plays an important role in colorectal carcinogenesis. Considering the frequent co-occurrence of PIK3CA and RAS mutations, conflicting data exist about its impact on prognosis of mCRC patients (pts) and its predictive role to anti-EGFR therapy. However, PI3K inhibitors have been developed and are currently under investigation in mCRC.
Methods
Data from mCRC pts treated at Azienda Ospedaliero-Universitaria Pisana from 1 Jan 2005 to 31 Dec 2017, whose tumours had been analysed per clinical practice by MALDI-TOF MassArray were retrieved. Association between PIK3CA mutation and clinico-pathological features was analysed by χ2 test; OS curves were estimated with Kaplan-Meier method and compared by log-rank test.
Results
Tumours from 90 (17%) out of 542 pts included in this analysis were PIK3CA mutated (mut), most of them in exon 9 (58.9%) or 20 (21.1%). Compared to PIK3CA wild-type (wt) tumours, mut ones were more often RAS mut (P = 0.006), MSI high (P = 0.008), and right-sided (P = 0.0004). Among 53 pts for whom PIK3CA status was available on both primary tumours (PT) and metastasis, the concordance was 92.4%. PIK3CA mutations were not associated with OS (36.4 vs 35.9 mos, HR 1.17, 95%CI 0.85-1.62, p = 0.3), with no difference among those affecting exon 9 and 20 (36.4 vs 27.5 mos, HR 0.77, 95%CI 0.39-1.54, p = 0.44). In RAS/BRAF wt (N 188) and in RAS mut (N 299) subgroup, no difference in terms of OS was found between PIK3CA mut and wt pts (38.1 vs 44.4 mos, HR 1.22, 95%CI 0.60-2.48, p = 0.55 and 27.5 vs 34.4 mos, HR 1.26, 95%CI 0.85-1.86, p = 0.22, respectively), though PIK3CA mut had shorter OS. In BRAF mut subgroup (N 54), PIK3CA mut pts had longer OS compared to PIK3CA wt (not reached vs 14.4 mos, HR 0.37, 95%CI 0.16-0.85, p = 0.09). Among 39 chemorefractory RAS/BRAF wt pts evaluable for response to an anti-EGFR agent, only 2 were exon 9 PIK3CA mut and achieved stable disease.
Conclusions
PIK3CA mut tumours displayed specific clinico-pathological features and a strong concordance was found between PT and paired metastases. Interestingly, a different impact on prognosis of PIK3CA mutation in RAS/BRAF wt, RAS mut or BRAF mut mCRC pts was observed and deserves validation.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Supported by ARCO (Associazione Ricerca e Cure in Oncologia) Foundation.
Disclosure
All authors have declared no conflicts of interest.
Resources from the same session
3516 - Palbociclib Rechallenge in Hormone Receptor (HR)[+]/HER2[-] Advanced Breast Cancer (ABC). PALMIRA Trial
Presenter: Antonio Llombart Cussac
Session: Poster Display session 2
Resources:
Abstract
4616 - Alpelisib (ALP) + Endocrine Therapy (ET) by Last Prior Therapy in Patients (pts) With PIK3CA-Mutated Hormone-Receptor Positive (HR+) Human Epidermal Growth Factor Receptor-2-Negative (HER2–) Advanced Breast Cancer (ABC): Additional Study Cohort in BYLieve
Presenter: Eva Ciruelos
Session: Poster Display session 2
Resources:
Abstract
3592 - PRECYCLE: Impact of CANKADO-based eHealth-support on quality of life in metastatic breast cancer patients treated with palbociclib and endocrine therapy.
Presenter: Tom Degenhardt
Session: Poster Display session 2
Resources:
Abstract
4168 - Efficacy and safety of oral poly (ADP-ribose) polymerase inhibitor fluzoparib in patients with BRCA1/2 mutations and platinum sensitive recurrent ovarian cancer
Presenter: Ning Li
Session: Poster Display session 2
Resources:
Abstract
2785 - Effect of response to last platinum-based chemotherapy in patients (pts) with platinum-sensitive, recurrent ovarian carcinoma in the phase 3 study ARIEL3 of rucaparib maintenance treatment
Presenter: Jonathan Ledermann
Session: Poster Display session 2
Resources:
Abstract
3496 - Integrated safety analysis of the poly(ADP-ribose) polymerase (PARP) inhibitor rucaparib in patients (pts) with ovarian cancer in the treatment and maintenance settings
Presenter: Rebecca Kristeleit
Session: Poster Display session 2
Resources:
Abstract
2844 - Clinical factors associated with prolonged response and survival under olaparib as maintenance therapy in BRCA mutated ovarian cancers
Presenter: S.Intidhar Labidi-Galy
Session: Poster Display session 2
Resources:
Abstract
1955 - A Prospective Evaluation of Tolerability of Niraparib Dosing Based on Baseline Body Weight (BW) and Platelet (plt) Count: Blinded Pooled Interim Safety Data from the NORA Study
Presenter: Xiaohua Wu
Session: Poster Display session 2
Resources:
Abstract
2539 - Evaluation of Niraparib 200 mg/d as Maintenance Therapy in Recurrent Ovarian Cancer and Associated Thrombocytopenia in a Real-World US Setting
Presenter: Premal Thaker
Session: Poster Display session 2
Resources:
Abstract
1290 - Niraparib initial dose and its’ management in patients with recurrent high-grade serous ovarian cancer.
Presenter: Jacek Grabowski
Session: Poster Display session 2
Resources:
Abstract