RESUMEN
PURPOSE: Despite significant improvement in therapeutic development in the past decades, breast cancer remains a formidable cause of death for women worldwide. The hormone positive subtype (HR(+)) (also known as luminal type) is the most prevalant category of breast cancer, comprising ~70% of patients. The clinical success of the three CDK4/6 inhibitors palbociclib, ribociclib, and abemaciclib has revolutionized the treatment of choice for metastatic HR(+) breast cancer. Accumulating evidence demonstrate that the properties of CDK4/6 inhibitors extend beyond inhibition of the cell cycle, including modulation of immune function, sensitizing PI3K inhibitors, metabolism reprogramming, kinome rewiring, modulation of the proteosome, and many others. The ubiquitin-proteasome pathway (UPP) is a crucial cellular proteolytic system that maintains the homeostasis and turnover of proteins. METHODS: We performed transcriptional profiling of the HR(+) breast cancer cell lines MCF7 and T47D treated with Palbociclib. Differential expressed genes were analyzed for novel pathways enriched. The results were further validated with biochemical assays and with real world clinical database cohorts. RESULTS: We uncovered a novel mechanism that demonstrate the CDK4/6 inhibitors suppress the expression of three ubiquitin conjugating enzymes UBE2C, UBE2S, UBE2T. Further validation in the HR(+) cell lines show that Palbociclib and ribociclib decrease UBE2C at both the mRNA and protein level, but this phenomenon was not shared with abemaciclib. These three E2 enzymes modulate several E3 ubiquitin ligases, including the APC/C complex which plays a role in G1/S progression. We further demonstrate the UBE2C/UBE2T expression levels are associated with breast cancer survival, and HR(+) breast cancer cells demonstrate dependence on the UBE2C. CONCLUSIONS: Our study suggests a novel link between CDK4/6 inhibitor and UPP pathway, adding to the potential mechanisms of their clinical efficacy in cancer.
Asunto(s)
Neoplasias de la Mama , Aminopiridinas , Bencimidazoles , Neoplasias de la Mama/patología , Quinasa 4 Dependiente de la Ciclina , Quinasa 6 Dependiente de la Ciclina , Femenino , Hormonas/uso terapéutico , Humanos , Fosfatidilinositol 3-Quinasas , Complejo de la Endopetidasa Proteasomal/uso terapéutico , Inhibidores de Proteínas Quinasas/uso terapéutico , Purinas , ARN Mensajero , Enzimas Ubiquitina-Conjugadoras/genética , Enzimas Ubiquitina-Conjugadoras/metabolismo , Ubiquitinas/uso terapéuticoRESUMEN
BACKGROUND: Studies with pertuzumab, a novel anti-HER2 antibody, show improved efficacy when combined with the established HER2-directed antibody trastuzumab in breast cancer therapy. We investigated the combination of pertuzumab or trastuzumab, or both, with docetaxel and the combination of pertuzumab and trastuzumab without chemotherapy in the neoadjuvant setting. METHODS: In this multicentre, open-label, phase 2 study, treatment-naive women with HER2-positive breast cancer were randomly assigned (1:1:1:1) centrally and stratified by operable, locally advanced, and inflammatory breast cancer, and by hormone receptor expression to receive four neoadjuvant cycles of: trastuzumab (8 mg/kg loading dose, followed by 6 mg/kg every 3 weeks) plus docetaxel (75 mg/m(2), escalating, if tolerated, to 100 mg/m(2) every 3 weeks; group A) or pertuzumab (loading dose 840 mg, followed by 420 mg every 3 weeks) and trastuzumab plus docetaxel (group B) or pertuzumab and trastuzumab (group C) or pertuzumab plus docetaxel (group D). The primary endpoint, examined in the intention-to-treat population, was pathological complete response in the breast. Neither patients nor investigators were masked to treatment. This study is registered with ClinicalTrials.gov, number NCT00545688. FINDINGS: Of 417 eligible patients, 107 were randomly assigned to group A, 107 to group B, 107 to group C, and 96 to group D. Patients given pertuzumab and trastuzumab plus docetaxel (group B) had a significantly improved pathological complete response rate (49 of 107 patients; 45·8% [95% CI 36·1-55·7]) compared with those given trastuzumab plus docetaxel (group A; 31 of 107; 29·0% [20·6-38·5]; p=0·0141). 23 of 96 (24·0% [15·8-33·7]) women given pertuzumab plus docetaxel (group D) had a pathological complete response, as did 18 of 107 (16·8% [10·3-25·3]) given pertuzumab and trastuzumab (group C). The most common adverse events of grade 3 or higher were neutropenia (61 of 107 women in group A, 48 of 107 in group B, one of 108 in group C, and 52 of 94 in group D), febrile neutropenia (eight, nine, none, and seven, respectively), and leucopenia (13, five, none, and seven, respectively). The number of serious adverse events was similar in groups A, B, and D (15-20 serious adverse events per group in 10-17% of patients) but lower in group C (four serious adverse events in 4% of patients). INTERPRETATION: Patients given pertuzumab and trastuzumab plus docetaxel (group B) had a significantly improved pathological complete response rate compared with those given trastuzumab plus docetaxel, without substantial differences in tolerability. Pertuzumab and trastuzumab without chemotherapy eradicated tumours in a proportion of women and showed a favourable safety profile. These findings justify further exploration in adjuvant trials and support the neoadjuvant approach for accelerating drug assessment in early breast cancer. FUNDING: F Hoffmann-La Roche.