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
5458 - Baseline characteristics from CLARINET FORTE: Evaluating lanreotide autogel (LAN) 120 mg every 14 days in patients with progressive pancreatic or midgut neuroendocrine tumours during a standard first-line LAN regimen.
Presenter: Philippe Ruszniewski
Session: Poster Display session 2
Resources:
Abstract
1234 - Analysis of PD-1/PD-L1 blockade biomarker and immune infiltrates in Gastroenteropancreatic neuroendocrine carcinoma
Presenter: Jia Zhang Xing
Session: Poster Display session 2
Resources:
Abstract
1517 - Diabetes Is Associated With Pancreatic Neuroendocrine Tumors Growth and Metastasis
Presenter: Zhiyao Fan
Session: Poster Display session 2
Resources:
Abstract
2145 - Investigation of the reclassification of G1/G2 pancreatic neuroendocrine neoplasms by WHO 2017 classification
Presenter: Takahiro Yokose
Session: Poster Display session 2
Resources:
Abstract
3134 - Treatment with somatostatin analogues after radiopeptide therapy
Presenter: Daria Handkiewicz Junak
Session: Poster Display session 2
Resources:
Abstract
2191 - Safety and Tolerability of Surufatinib in Western Patients with Solid Tumors
Presenter: Erika Hamilton
Session: Poster Display session 2
Resources:
Abstract
3253 - The impact of tumour absorbed dosimetry with survival outcomes after peptide receptor radionuclide therapy in metastatic neuroendocrine tumours.
Presenter: Rahul Ladwa
Session: Poster Display session 2
Resources:
Abstract
3581 - Opportunist and Serious Infections in Patients with Neuroendocrine Tumors Treated With Everolimus: A Multicenter Study of Real World Patients
Presenter: Carine Mauro
Session: Poster Display session 2
Resources:
Abstract
5374 - Establishment of Prognostic Nomogram Based on the Metastatic Lymph Nodes Ratio for Patients with Gastric Neuroendocrine Tumour
Presenter: yaobin lin
Session: Poster Display session 2
Resources:
Abstract
3951 - Neutrophil-lymphocyte ratio as an independent predictive factor in Neuroendocrine Neoplasms
Presenter: Sofia Ferreira
Session: Poster Display session 2
Resources:
Abstract