Resistance to CDK4/6 inhibition: Mechanisms and strategies to overcome a therapeutic problem in the treatment of hormone receptor-positive metastatic breast cancer.

Selective CDK4/6 inhibitors, such as palbociclib, ribociclib, and abemaciclib, have been approved in combination with hormone therapy for the treatment of patients with HR+, HER2-negative advanced or metastatic breast cancer (mBC). Despite their promising activity, approximately 10 % of patients have de novo resistance, while the rest of them will develop acquired resistance after 24-28 months when used as first-line therapy and after a shorter period when used as second-line therapy. Various mechanisms of resistance to CDK4/6 inhibitors have been described, including cell cycle-related mechanisms, such as RB loss, p16 amplification, CDK6 or CDK4 amplification, and cyclin E-CDK2 amplification. Other bypass mechanisms involve the activation of FGFR or PI3K/AKT/mTOR pathways. Identifying the different mechanisms by which resistance to CDK4/6 inhibitors occurs may help to design new treatment strategies to improve patient outcomes. This review presents the currently available knowledge on the mechanisms of resistance to CDK4/6 inhibitors, explores possible treatment strategies that could overcome this therapeutic problem, and summarizes relevant recent clinical trials.

Efficacy and Safety of Neoadjuvant Treatment with Bevacizumab, Liposomal Doxorubicin, Cyclophosphamide and Paclitaxel Combination in Locally/Regionally Advanced, HER2-Negative, Grade III at Premenopausal Status Breast Cancer: A Phase II Study.

BACKGROUND: In the era of personalized therapy, targeted treatment in specific patient populations is mandated. OBJECTIVE: We evaluated the efficacy and safety of neoadjuvant treatment on locally advanced breast cancer (LABC) with a monoclonal agent against vascular endothelial growth factor (VEGF), bevacizumab plus chemotherapy combination of liposomal doxorubicin, cyclophosphamide and paclitaxel (PLAC-B). METHODS: Patients enrolled were at premenopausal status and characterized by human epidermal growth factor receptor 2 (HER2)-negative, hormone-receptor positive (estrogen receptor/progesterone receptor-positive [ER/PR+]) or triple-negative (TNBC), LABC (T > 3 cm), with high-grade ductal carcinoma. Patients had to have a measurable disease and Eastern Cooperative Oncology Group (ECOG) performance status (PS) of 0, with adequate hematologic, renal, and hepatic function. Patients received intravenous liposomal doxorubicin 30 mg/m2, cyclophosphamide 600 mg/m2, paclitaxel 120 mg/m2, and bevacizumab 8 mg/kg on day 1 of 15-day cycles for four cycles (four administrations as neoadjuvant treatment). The primary endpoint was complete clinical (cCR) and pathologic (pCR) response rates, while secondary endpoints included safety, breast-conserving surgery (BCS) conversion rate, and disease-free survival (DFS). RESULTS: Sixty-two women were enrolled; 20 were ER/PR+ and 42 had TNBC. All underwent surgery, six received mastectomy, and 56 (90.3%) received BCS, with an equal conversion rate from initial indication for mastectomy. cCR was 25.8%. pCR in the breast and axilla occurred in 24 patients (38.7%). pCR was 42.9% for TNBC and 30% for ER/PR+. Hematologic adverse events (AEs) included neutropenia (74.2% total; 22.6% grade 3 [G3]) and febrile neutropenia (6.5% G3); non-hematologic G3 AEs included nausea (6.5%), mucositis (9.7%), and infection (3.2%), all of which were managed without negative sequelae. Over a 3-year follow-up, all patients were alive and DFS was 87.1%. CONCLUSION: PLAC-B as neoadjuvant treatment of this subpopulation with TNBC and ER/PR+ patients is effective and safe. Further studies are necessitated.

Margin-free excision of small solid breast carcinomas using the Intact Breast Lesion Excision System®: is it feasible?

BACKGROUND: The Breast Lesion Excision System® (BLES®) is a stereotactic vacuum-assisted breast biopsy device that utilizes radiofrequency in order to excise non-palpable mammographic lesions for pathologic diagnosis. The purpose of this study was to evaluate the efficacy of BLES® in performing complete, margin-free excisions of small solid carcinomas. METHODS: Our retrospective study of prospectively enrolled patients included 50 cases of non-palpable, BIRADS ≥ 4, solid by means of mammography and sonography, lesions. All these patients underwent a BLES® breast biopsy procedure from June 2010 to June 2014 and had a malignant diagnosis. According to each patient's pathologic diagnosis, appropriate surgical treatment was recommended. Postoperatively, surgical specimens were histologically analyzed, aiming to determine whether residual malignant disease was present in the specimen cavity formatted by BLES®. RESULTS: Ductal carcinoma in situ (DCIS) was diagnosed in 5 patients and invasive carcinoma (IC) in 45 patients, at primary BLES® pathology report. Tumor-free resection margins (< 0.5 and < 1 mm) were accomplished in only 8/24 subcentimeter cases (33.3%). Absence of residual disease upon surgical excision was confirmed in 23/24 subcentimeter cases (95.8%) and 2/26 of the cases measuring > 1 cm (7.69%). Statistical analysis revealed that mammographic size was the only significant prognostic factor for complete excision (i.e., with no residual disease in the biopsy cavity) of a malignant lesion. CONCLUSIONS: Our results indicate that it is possible, when using the BLES® device, to completely excise small (≤ 10 mm) breast carcinomas that appear radiologically as solid lesions. This subset of patients should be investigated regarding the therapeutic potential of this method.

Basal phenotype breast cancer: implications for treatment and prognosis.

Breast cancer is the most common malignancy in females. The origins and biology of breast carcinomas remain unclear. Cellular and molecular heterogeneity results in different distinct groups of tumors with different clinical behavior and prognosis. Gene expression profiling has delineated five molecular subtypes based on similarities in gene expression: luminal A, luminal B, HER2 overexpressing, normal-like and basal-like. Basal-like breast cancer (BLBC) lacks estrogen receptor, progesterone receptor and HER2 expression, and comprises myoepithelial cells. Specific features include high proliferative rate, rapid growth, early recurrence and decreased overall survival. BLBC is associated with ductal carcinoma in situ, BRCA1 mutation, brain and lung metastasis, and negative axillary lymph nodes. Currently, chemotherapy is the only therapeutic choice, but demonstrates poor outcomes. There is an overlap in definition between triple-negative breast cancer and BLBC due to the triple-negative profile of BLBC. Despite the molecular and clinical similarities, the two subtypes respond differently to neoadjuvant therapy. Although particular morphologic, genetic and clinical features of BLBC have been identified, a variety of definitions among studies accounts for the contradictory results reported. In this article the molecular morphological and histopathological profile, the clinical behavior and the therapeutic options of BLBC are presented, with emphasis on the discordant findings among studies.

Which patients need an axillary clearance after sentinel node biopsy?

Sentinel lymph node biopsy (SLNB) is a safe and accurate minimally invasive method for detecting axillary lymph node (ALN) involvement in the clinically negative axilla thereby reducing morbidity in patients who avoid unnecessary axillary lymph node dissection (ALND). Although current guidelines recommend completion ALND when macro- and micrometastatic diseases are identified by SLNB, the benefit of this surgical intervention is under debate. Additionally, the management of the axilla in the presence of isolated tumour cells (ITCs) in SLNB is questioned. Particularly controversial is the prognostic significance of minimal SLNB metastasis in relation to local recurrence and overall survival. Preliminary results of the recently published Z0011 trial suggest similar outcomes after SNB or ALND when the SN is positive, but this finding has to be interpreted with caution.

Decreased Hsp90 expression in infiltrative lobular carcinoma: an immunohistochemical study.

BACKGROUND: Elevated Hsp90 expression has been documented in breast ductal carcinomas, whereas decreased Hsp90 expression has been reported in precursor lobular lesions. This study aims to assess Hsp90 expression in infiltrative lobular carcinomas of the breast. METHODS: Tissue specimens were taken from 32 patients with infiltrative lobular carcinoma. Immunohistochemical assessment of Hsp90 was performed both in the lesion and the adjacent normal breast ducts and lobules; the latter serving as control. Concerning Hsp90 assessment: i) the percentage of positive cells and ii) the intensity were separately analyzed. Subsequently, the Allred score was adopted and calculated. The intensity was treated as an ordinal variable-score (0: negative, low: 1, moderate: 2, high: 3). Statistical analysis followed. RESULTS: All infiltrative lobular carcinoma foci mainly presented with a positive cytoplasmic immunoreaction for Hsp90. Compared to the adjacent normal ducts and lobules, infiltrative lobular carcinoma exhibited a statistically significant decrease in Hsp90 expression, both in terms of Hsp90 positive cells (%) and Allred score (74.2 +/- 11.2 vs. 59.1 +/- 14.2 p = 0.0001; 7.00 +/- 0.95 vs. 6.22 +/- 1.01, p = 0.007, Wilcoxon matched-pairs signed-ranks test). Concerning the intensity of Hsp90 immunostaining only a marginal decrease was noted (2.16 +/- 0.68 vs. 1.84 +/- 0.63, p = 0.087, Wilcoxon matched-pairs signed-ranks test). CONCLUSION: ILC lesions seem to exhibit decreased Hsp90 expression, a finding contrary to what might have been expected, given that high Hsp90 expression is a trait of invasive ductal carcinomas.

Malignant carcinoid tumor of the cystic duct: a rare cause of bile duct obstruction.

BACKGROUND: Carcinoid tumors of the extrahepatic biliary tree are extremely rare malignancies, accounting for 0.2%-2% of all gastrointestinal carcinoid tumors, while carcinoids of the cystic duct are an uncommon entity and an extremely unusual cause of bile duct obstruction. METHODS: After an extensive literature review, we retrospectively analysed 61 cases of carcinoid tumor of the biliary tree as well as one additional case of a 60-year-old female with symptoms and laboratory/imaging examination findings compatible with those of a malignant biliary tract obstruction. At laparotomy, resection of the gallbladder and common bile duct was performed. Histological study revealed a well-differentiated neuro-endocrine carcinoma of the cystic duct. The patient remained disease-free at 16 months. RESULTS: Our presentation is the seventh case reported in the world literature. Compared to cholangiocarcinoma, analysis of the reviewed group indicates an increased incidence of extrahepatic carcinoid tumors in younger persons along with a slight female predominance. Statistically, the most common anatomic location is the common bile duct, followed by the perihilar region and the cystic duct. Jaundice is the most common finding. Curative surgery was realized in the majority of cases and long-term disease-free survival was achieved when surgery was curative. CONCLUSIONS: Carcinoid tumors obstructing the biliary tree are extremely difficult to diagnose preoperatively, and nearly impossible to differentiate from non-neuroendocrine tumors. As surgery offers the only potential cure for both biliary carcinoids and cholangiocarcinoma, we recommend aggressive surgical therapy as the treatment of choice in every case of potentially resectable biliary tumor.

Change in preoperative strategy based on intraoperative ultrasound findings.

Forty patients with primary liver carcinoma and 52 with liver secondaries underwent careful preoperative evaluation using computed tomography and magnetic resonance imaging, as well as intraoperative studies using intraoperative ultrasound (IOUS). The results were compared to histological findings. In the 40 patients with primary tumors who underwent hepatic resection, 4 (9.1%) additional lesions were found using IOUS, and in 10 (25%) instances, our preoperative strategy was changed (either a more extensive or more conservative excision was performed). In the 52 cases with metastatic disease who underwent hepatic resection, 14 (21.2%) more lesions were detected, and in 15 (29%) patients, the preoperative strategy was changed. Based on IOUS findings, of 92 patients, a total of 18 (16.4%) additional lesions were detected; in addition, our preoperative strategy changed in 25 (27.2%) of the cases with primary and secondary liver tumors.

Evaluation of long-lasting sensorimotor consequences following neonatal hypoxic-ischemic brain injury in rats: the neuroprotective role of MgSO4.

Perinatal asphyxia (PA) is a major determinant for long-term sensorimotor and locomotor deficits. The model of neonatal hypoxia-ischemia (HI) in 7-day-old rats produces sensorimotor cortex, thalamus and striatum injury, which are all critical for the maintenance of sensory motor function. The aim of this study was to evaluate the long-term neurodevelopmental disturbances in the above experimental model and to assess the neuroprotective effect of MgSO(4) in terms of long-term behavioral and morphological changes. Seven-day-old rats were separated into three groups: A (control), neither ligated nor exposed to hypoxia; B (HI/MgSO(4)) ligated, exposed to hypoxia and treated with MgSO(4) (2 g/kg b.w., i.p.), and C (HI) ligated and exposed to hypoxia. At the age of 42 days, the behavior of the rats was evaluated using 5 sensorimotor tests. Muscle power, motor coordination, reflexes, and limb placing were tested to different sensory stimuli. The study was completed with the histopathological evaluation of brain tissue damage. In all individual tests the HI-treated rats performed significantly worse than the control and MgSO(4)-treated rats and this difference was more pronounced in the limb placing tests. Additionally, neonatal HI resulted in extensive neuronal damage that was limited after MgSO(4) administration. Behavioral alterations represent a useful endpoint for studying the consequences of a perinatal HI insult and the efficacy of potential neuroprotective treatments. MgSO(4) administration resulted in prevention of HI-induced sensorimotor deficits and brain injury.

Neuroprotective effect of long-term MgSO4 administration after cerebral hypoxia-ischemia in newborn rats is related to the severity of brain damage.

Previous studies have shown contradictory results regarding magnesium-mediated neuroprotection in animal models of perinatal asphyxia. The aim of this study is to investigate the effects of MgSO(4) postasphyxial treatment on hypoxia-ischemia (HI)-induced brain injury in neonatal rats and the possibility that this effect is related to the severity of brain damage. Seven-day-old rats underwent unilateral carotid artery ligation followed by 1 or 2 hours of hypoxia (8% O(2)) and MgSO(4) administration. Adenosine triphosphate/phosphocreatine and glutamate/glutamine measurements and neuropathological evaluation of the hippocampus were used to assess the effects of HI and MgSO(4). HI caused time-dependent changes in energy stores, amino acid concentrations, and brain damage. Administration of MgSO(4) after 1 hour but not after 2 hours of hypoxia resulted in significant prevention of HI-induced brain injury. MgSO(4) administration results in a significant protection against moderate HI-induced brain damage, whereas it fails to offer a similar effect against severe brain damage.

Erythropoietin prevents long-term sensorimotor deficits and brain injury following neonatal hypoxia-ischemia in rats.

Perinatal asphyxia accounts for behavioral dysfunctions that often manifest as sensorimotor, learning or memory disabilities throughout development and into maturity. Erythropoietin (Epo) has been shown to exert neuroprotective effects in different models of brain injury including experimental models of perinatal asphyxia. However, the effect of Epo on functional abilities following cerebral hypoxia-ischemia (HI) in neonatal rats is not known. The aim of the present study is to investigate the effect of Epo on sensorimotor deficits and brain injury induced by hypoxia-ischemia. Seven-day-old rats underwent unilateral, permanent carotid artery ligation followed by 1 h of hypoxia. Epo was administered as a single dose immediately after the hypoxic insult (2000 U/kg). The neuroprotective effect of Epo was evaluated at postnatal day 42 by using a battery of behavioral tests and histological analysis. The results of the present study suggest that Epo treatment immediately after HI insult significantly facilitated recovery of sensorimotor function. Consistently, histopathological evaluation demonstrated that Epo significantly attenuated brain injury and preserved the integrity of cerebral cortex. These findings indicate that long-term neuroprotective effect of Epo on neonatal HI-induced brain injury might be associated with the preservation of sensorimotor functions.

E2F-1 transcription factor immunoexpression is inversely associated with tumor growth in colon adenocarcinomas.

E2F-1 is an intriguing transcription factor that accumulates the integrated signal of the G1-S transition regulators. Its role in cell fate, as depicted from in vivo models and a few studies on human tissues, is a matter of debate, since it confers a tissue-specific oncogenic or tumor suppressor behavior. In the present work, in an attempt to shed light on the role of E2F-1 in colon cancer, we examined E2F-1 expression in a series of 45 colon carcinomas and we further correlated it with tumor kinetics. E2F-1 expression and proliferation were evaluated by immunohistochemistry as the percentage of E2F-1 (E2F-1 index: EI) and Ki-67 (Proliferation index: PI)-positive cells, respectively; whereas apoptosis was estimated as the percentage of positive, by TUNEL assay, cells (Apoptotic index: AI). The relationship between E2F-1 expression and tumor kinetics was assessed by microscopical evaluation in semi-serial tissue sections and statistical analysis. Our results demonstrated that E2F-1 expression was inversely correlated with tumor growth (GI=PI/AI) (p=0.002). Specifically, the histological observations showed that E2F-1 was expressed in lesions with high apoptotic incidence and low proliferation. These results also supported the statistical findings showing that EI was inversely correlated with PI (p < 0.001) and positively associated with AI (p = 0.013). In conclusion, we suggest a tumor-suppressive behavior of E2F-1 in colon carcinomas.