Purpose: To identify potential predictors of response and resistance mechanisms in patients with hormone receptor-positive (HR+), HER2-negative (HER2-) advanced breast cancer (ABC) treated with the cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitor abemaciclib ± endocrine therapy (ET), baseline and acquired genomic alterations in circulating tumor DNA (ctDNA) were analyzed and associated with clinical outcomes.
Experimental Design: MONARCH 3: postmenopausal women with HR+, HER2- ABC and no prior systemic therapy in the advanced setting were randomly assigned to abemaciclib or placebo plus nonsteroidal aromatase inhibitor (NSAI). nextMONARCH: women with HR+, HER2- metastatic breast cancer that progressed on/after prior ET and chemotherapy were randomly assigned to abemaciclib alone (two doses) or plus tamoxifen.
Purpose: PIK3CA and ESR1 mutations have been implicated in resistance to endocrine therapy (ET) in HR+, HER2- advanced breast cancer (ABC). Inhibition of CDK4 and 6 has been hypothesized as a therapeutic strategy to overcome endocrine resistance in patients with PIK3CA- or ESR1-mutant breast cancers. The objective of this exploratory analysis was to assess efficacy of abemaciclib plus fulvestrant in patients with or without PIK3CA or ESR1 mutations in MONARCH 2.
View Article and Find Full Text PDFPurpose: Cyclin-dependent kinase 4 (CDK4) and CDK6 inhibitors (CDK4/6i) are highly effective against estrogen receptor-positive (ER)/HER2 breast cancer; however, intrinsic and acquired resistance is common. Elucidating the molecular features of sensitivity and resistance to CDK4/6i may lead to identification of predictive biomarkers and novel therapeutic targets, paving the way toward improving patient outcomes.
Experimental Design: Parental breast cancer cells and their endocrine-resistant derivatives (EndoR) were used.
The 17q23 amplicon is associated with poor outcome in ER breast cancers, but the causal genes to endocrine resistance in this amplicon are unclear. Here, we interrogate transcriptome data from primary breast tumors and find that among genes in 17q23, PRR11 is a key gene associated with a poor response to therapeutic estrogen suppression. PRR11 promotes estrogen-independent proliferation and confers endocrine resistance in ER breast cancers.
View Article and Find Full Text PDFMechanisms driving resistance to cyclin-dependent kinase 4/6 inhibitors (CDK4/6i) in hormone receptor-positive (HR) breast cancer have not been clearly defined. Whole-exome sequencing of 59 tumors with CDK4/6i exposure revealed multiple candidate resistance mechanisms including loss, activating alterations in , and , and loss of estrogen receptor expression. experiments confirmed that these alterations conferred CDK4/6i resistance.
View Article and Find Full Text PDFAberrant activation of mitogenic signaling pathways in cancer promotes growth and proliferation of cells by activating mTOR and S6 phosphorylation, and D-cyclin kinases and Rb phosphorylation, respectively. Correspondingly, inhibition of phosphorylation of both Rb and S6 is required for robust anti-tumor efficacy of drugs that inhibit cell signaling. The best-established mechanism of mTOR activation in cancer is via PI3K/Akt signaling, but mTOR activity can also be stimulated by CDK4 and PIM kinases.
View Article and Find Full Text PDFPurpose: neoMONARCH assessed the biological effects of abemaciclib in combination with anastrozole in the neoadjuvant setting.
Patients And Methods: Postmenopausal women with stage I-IIIB HR/HER2 breast cancer were randomized to a 2-week lead-in of abemaciclib, anastrozole, or abemaciclib plus anastrozole followed by 14 weeks of the combination. The primary objective evaluated change in Ki67 from baseline to 2 weeks of treatment.
Using an ORF kinome screen in MCF-7 cells treated with the CDK4/6 inhibitor ribociclib plus fulvestrant, we identified FGFR1 as a mechanism of drug resistance. FGFR1-amplified/ER+ breast cancer cells and MCF-7 cells transduced with FGFR1 were resistant to fulvestrant ± ribociclib or palbociclib. This resistance was abrogated by treatment with the FGFR tyrosine kinase inhibitor (TKI) lucitanib.
View Article and Find Full Text PDFUpregulation of the PI3K pathway has been implicated in the initiation and progression of several types of cancer, including renal cell carcinoma (RCC). Although several targeted therapies have been developed for RCC, durable and complete responses are exceptional. Thus, advanced RCC remains a lethal disease, underscoring the need of robust biomarker-based strategies to treat RCC.
View Article and Find Full Text PDFThe majority of deaths from MBC are in patients with hormone receptor (HR) positive, HER2 negative disease. Endocrine therapy (ET) remains the backbone of treatment in these cases, improving survival and quality of life. However, treatment can lose effectiveness due to primary or acquired endocrine resistance.
View Article and Find Full Text PDFPalbociclib is a CDK4/6 inhibitor approved for metastatic estrogen receptor-positive breast cancer. In addition to G1 cell cycle arrest, palbociclib treatment results in cell senescence, a phenotype that is not readily explained by CDK4/6 inhibition. In order to identify a molecular mechanism responsible for palbociclib-induced senescence, we performed thermal proteome profiling of MCF7 breast cancer cells.
View Article and Find Full Text PDFThis study aimed to identify biomarkers of resistance to endocrine therapy in estrogen receptor-positive (ER) breast cancers treated with prolonged neoadjuvant letrozole. We performed targeted DNA and RNA sequencing in 68 ER breast cancers from patients treated with preoperative letrozole (median, 7 months). Twenty-four tumors (35%) exhibited a PEPI score ≥4 and/or recurred after a median of 58 months and were considered endocrine resistant.
View Article and Find Full Text PDFAnticancer Agents Med Chem
June 2019
Lung cancer is the leading cause of cancer-related mortality around the world, despite effective chemotherapeutic agents, the prognosis has remained poor for a long time. The discovery of molecular changes that drive lung cancer has led to a dramatic shift in the therapeutic landscape of this disease. In "in vitro" and "in vivo" models of NSCLC (Non-Small Cell Lung Cancer), angiogenesis blockade has demonstrated an excellent anti-tumor activity, thus, a number of anti-angiogenic drugs have been approved by regulatory authorities for use in clinical practice.
View Article and Find Full Text PDFamplification occurs in approximately 15% of estrogen receptor-positive (ER) human breast cancers. We investigated mechanisms by which amplification confers antiestrogen resistance to ER breast cancer. ER tumors from patients treated with letrozole before surgery were subjected to Ki67 IHC, FGFR1 FISH, and RNA sequencing (RNA-seq).
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