Abstract 5873
Background
CNS metastases is a devastating complication of breast cancer, occurring in approximately 10%–15% of patients with metastatic breast cancer (MBC) and resulting in median survival of less than one year in historic cohorts. Biological factors that govern metastases to the brain, including the role of activating PIK3CA mutations, the most common actionable alterations in HR+/HER2- MBC, are poorly understood.
Methods
In this retrospective cohort study, we determined the cumulative incidence of brain metastasis in PIK3CA mutant and PIK3CA non-mutant HR+/HER2- MBC patients treated at the Massachusetts General Hospital and genotyped during their routine clinical care with a highly sensitive multiplexed assay for real time mutation profiling of clinical samples.
Results
In the overall cohort of 307 patients, 120 patients (39.1%) had PIK3CA mutant disease and 187 patients (60.9%) had PIK3CA non-mutant disease, comparable to previously published results. Median OS from the time of diagnosis of metastatic disease was 3.96 yrs (95% CI 3.40-4.87 yrs) for PIK3CA mutant patients and 4.43 yrs (95% CI 3.82-5.32 yrs) for PIK3CA non-mutant patients, p = 0.6. 22.44% of patients with HR+/HER2- disease developed brain metastases; 30.83% of PIK3CA mutant patients and 17.11% of PIK3CA non-mutant patients developed CNS metastases, p = 0.0049. Median time to the development of CNS disease was 8.61 yrs for PIK3CA mutant subset and not reached (NR) for PIK3CA non-mutant subset, p = 0.0086. Among patients with CNS metastases, median OS for PIK3CA mutant patients was 0.48 yrs (95% CI 0.27-0.74) and for PIK3CA non-mutant it was 1.09 yrs (95% CI 0.39-2.27), p = 0.019).
Conclusions
Brain metastases are common in HR+/HER2- MBC. This incidence of brain metastases is particularly high among patients with HR+/HER2- tumors harboring a PIK3CA mutation, where it approaches the incidence historically seen in HER2+ MBC. Early recognition of symptoms potentially related to brain metastases is important even in HR+/HER2- subtype of breast cancer. High incidence of brain metastases in PIK3CA mutant HR+/HER2- MBC warrants development of blood-brain barrier penetrant agents targeting the PI3K/AKT/mTOR pathway.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
S. Isakoff: Advisory / Consultancy, Research grant / Funding (institution): Myriad; Advisory / Consultancy, Research grant / Funding (institution): Puma; Advisory / Consultancy, Research grant / Funding (institution): Immunomedics; Advisory / Consultancy, Research grant / Funding (institution): Mylan; Advisory / Consultancy, Research grant / Funding (institution): Genentech; Advisory / Consultancy, Research grant / Funding (institution): Pharmamar; Advisory / Consultancy, Research grant / Funding (institution): Abbvie; Advisory / Consultancy, Research grant / Funding (institution): OncoPep; Advisory / Consultancy, Research grant / Funding (institution): Merck; Advisory / Consultancy, Research grant / Funding (institution): AstraZeneca. A. Bardia: Advisory / Consultancy, Research grant / Funding (institution): Genentech/Roche; Advisory / Consultancy, Research grant / Funding (institution): Immunomedics; Advisory / Consultancy, Research grant / Funding (institution): Novartis; Advisory / Consultancy, Research grant / Funding (institution): Pfizer; Advisory / Consultancy, Research grant / Funding (institution): Merck; Advisory / Consultancy, Research grant / Funding (institution): Radius Health; Advisory / Consultancy, Research grant / Funding (institution): Specturm; Advisory / Consultancy, Research grant / Funding (institution): Taiho Pharmaceutical; Research grant / Funding (institution): Mersana; Research grant / Funding (institution): Innocrin; Research grant / Funding (self): Biothernostics. P.K. Brastianos: Research grant / Funding (institution): Merck; Research grant / Funding (institution): Pfizer; Research grant / Funding (institution): Bristol-Myer Squibb; Advisory / Consultancy: Genentech-Roche; Advisory / Consultancy: Merck; Advisory / Consultancy: Lily; Advisory / Consultancy: TESARO; Advisory / Consultancy: AngioChem. D. Juric: Advisory / Consultancy, Research grant / Funding (self), Research grant / Funding (institution): Novartis; Advisory / Consultancy, Research grant / Funding (institution): Genentech; Advisory / Consultancy, Research grant / Funding (institution): Eisai; Advisory / Consultancy, Research grant / Funding (institution): EMD Serono; Advisory / Consultancy, Research grant / Funding (institution): Syros; Advisory / Consultancy: Ipsen; Research grant / Funding (institution): Takeda; Research grant / Funding (institution): Celgene; Research grant / Funding (institution): Placon Therapeutics. All other authors have declared no conflicts of interest.
Resources from the same session
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
3353 - Results of the 3rd interim analysis of C-Patrol: A non-interventional study on olaparib in German routine clinical practice
Presenter: Jalid Sehouli
Session: Poster Display session 2
Resources:
Abstract