The Role of mTOR Inhibitors in Breast Cancer

509 Background: The role of PI3Kp dysregulation as a predictor of sensitivity to PI3Kpi is unclear. We aimed to evaluate the efficacy of PI3Kpi in two cohorts of MBC pts with assessable PI3Kp status. Methods: MBC pts treated in ≥3rd line with PI3Kpi were reviewed. PI3Kp status: (a) No dysregulation: PIK3CA wt and PTEN normal; (b) PI3Kp dysregulation: PIK3CA mutation (PIK3CAmut) or PTEN low (HScore≤50). Cohort A: pts treated with single agent PI3Kpi. Cohort B: pts treated with PI3Kpi in combination with hormonal therapy (HT), chemotherapy (CT) and/or trastuzumab (T). Results: Out of 232 MBC pts screened for PI3Kp alterations from Sep09 to Sep11, 32 were treated with PI3Kpi. Cohort A (n=17): HR+/HER2- 88%, HER2+ 6%, triple negative 6%; median age 43, median MBC lines 4 (2-9); PIK3CAmut in 10/17 (58.8%; 6 exon9, 4 exon20), PTEN low 3/17 (17.6%), 1 pt both; PI3Kp dysregulation 12/17 pts. Cohort B (n=15): HR+/HER2- 40%, HER2+ 60%; median age 49, median MBC lines 4 (2-13); PIK3CAmut 3/13 assessable (23.1%; all exon20), PTEN low 6/15 (40%), 1 pt both; PI3Kp dysregulation 8/15 pts. Time to progression to PI3Kpi (TTP), overall survival from MBC diagnosis (OSMBC) and OS from PI3Kpi beginning (OSPI3Kpi), according to PIK3CA status and PI3Kp dysregulation, are shown. No differences were found according to PTEN status. Conclusions: These results suggest that the best outcomes with PI3Kpi in PIK3CAmut MBC pts occur when they are used in combination with HT/CT/T. Activity of non selective PI3Kpi used as single agents seems to be limited, making results from prospective trials with selective PI3Kα inhibitors and PI3Kpi in combinations eagerly awaited. [Table: see text]

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Role of the IGF-1 Axis in Overcoming Resistance in Breast Cancer

Frontiers in Cell and Developmental Biology ◽

10.3389/fcell.2021.641449 ◽

2021 ◽

Vol 9 ◽

Author(s):

Anna Ianza ◽

Marianna Sirico ◽

Ottavia Bernocchi ◽

Daniele Generali

Keyword(s):

Breast Cancer ◽

Mtor Inhibitors ◽

Resistance Mechanisms ◽

Therapeutic Strategies ◽

Estrogen Regulation ◽

Physiological Processes ◽

Proliferation And Metastasis ◽

Cell Proliferation And Metastasis ◽

Important Therapeutic Target

Over the last two decades, many studies have demonstrated that the insulin-like growth factor-1 (IGF-1) is involved in a number of patho-physiological processes, as well as in the development of different types of solid tumors, including breast cancer (BC). Preclinical and clinical data showed that IGF-1 receptor (R) is overexpressed and hyper-phosphorylated in several subtypes of BCs. The central implications of this pathway in tumor cell proliferation and metastasis make it an important therapeutic target. Moreover, the IGF-1 axis has shown strong interconnection with estrogen regulation and endocrine therapy, suggesting a possible solution to anti-estrogen resistance. IGF-1R might also interfere with other pivotal therapeutic strategies, such as anti HER2 treatments and mTOR inhibitors; several clinical trials are ongoing evaluating the role of IGF-1R inhibition in modulating resistance mechanisms to target therapies. Our aim is to offer an overview of the most recent and significant field of application of IGF-1 inhibitors and relevant therapeutic strategies, weighing their possible future impact on clinical practice.

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Activation of PI3K/AKT/mTOR Pathway Causes Drug Resistance in Breast Cancer

Frontiers in Pharmacology ◽

10.3389/fphar.2021.628690 ◽

2021 ◽

Vol 12 ◽

Author(s):

Chao Dong ◽

Jiao Wu ◽

Yin Chen ◽

Jianyun Nie ◽

Ceshi Chen

Keyword(s):

Breast Cancer ◽

Drug Resistance ◽

Cancer Progression ◽

Critical Role ◽

Acquired Resistance ◽

Mtor Inhibitors ◽

Disease Recurrence ◽

Mtor Pathway ◽

Breast Cancer Patients

Although chemotherapy, targeted therapy and endocrine therapy decrease rate of disease recurrence in most breast cancer patients, many patients exhibit acquired resistance. Hyperactivation of the PI3K/AKT/mTOR pathway is associated with drug resistance and cancer progression. Currently, a number of drugs targeting PI3K/AKT/mTOR are being investigated in clinical trials by combining them with standard therapies to overcome acquired resistance in breast cancer. In this review, we summarize the critical role of the PI3K/AKT/mTOR pathway in drug resistance, the development of PI3K/AKT/mTOR inhibitors, and strategies to overcome acquired resistance to standard therapies in breast cancer.

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