Abstract 3101: In-vitro characterization of Abemaciclib pharmacology in ER+ breast cancer cell lines

The CDK4/6 inhibitor revolution - a game-changing era for breast cancer treatment

Cyclin-dependent kinase (CDK) 4/6 inhibition in combination with endocrine therapy is the standard-of-care treatment for patients with advanced-stage hormone receptor-positive, HER2 non-amplified (HR+HER2-) breast cancer. These agents can also be administered as adjuvant therapy to patients with higher-risk early stage disease. Nonetheless, the clinical success of these agents has created several challenges, such as how to address acquired resistance, identifying which patients are most likely to benefit from therapy prior to treatment, and understanding the optimal timing of administration and sequencing of these agents. In this Review, we describe the rationale for targeting CDK4/6 in patients with breast cancer, including a summary of updated clinical evidence and how this should inform clinical practice. We also discuss ongoing research efforts that are attempting to address the various challenges created by the widespread implementation of these agents.

Drugging Hijacked Kinase Pathways in Pediatric Oncology: Opportunities and Current Scenario

Childhood cancer is considered rare, corresponding to ~3% of all malignant neoplasms in the human population. The World Health Organization (WHO) reports a universal occurrence of more than 15 cases per 100,000 inhabitants around the globe, and despite improvements in diagnosis, treatment and supportive care, one child dies of cancer every 3 min. Consequently, more efficient, selective and affordable therapeutics are still needed in order to improve outcomes and avoid long-term sequelae. Alterations in kinases' functionality is a trademark of cancer and the concept of exploiting them as drug targets has burgeoned in academia and in the pharmaceutical industry of the 21st century. Consequently, an increasing plethora of inhibitors has emerged. In the present study, the expression patterns of a selected group of kinases (including tyrosine receptors, members of the PI3K/AKT/mTOR and MAPK pathways, coordinators of cell cycle progression, and chromosome segregation) and their correlation with clinical outcomes in pediatric solid tumors were accessed through the R2: Genomics Analysis and Visualization Platform and by a thorough search of published literature. To further illustrate the importance of kinase dysregulation in the pathophysiology of pediatric cancer, we analyzed the vulnerability of different cancer cell lines against their inhibition through the Cancer Dependency Map portal, and performed a search for kinase-targeted compounds with approval and clinical applicability through the CanSAR knowledgebase. Finally, we provide a detailed literature review of a considerable set of small molecules that mitigate kinase activity under experimental testing and clinical trials for the treatment of pediatric tumors, while discuss critical challenges that must be overcome before translation into clinical options, including the absence of compounds designed specifically for childhood tumors which often show differential mutational burdens, intrinsic and acquired resistance, lack of selectivity and adverse effects on a growing organism.

Abemaciclib-loaded ethylcellulose based nanosponges for sustained cytotoxicity against MCF-7 and MDA-MB-231 human breast cancer cells lines

Abemaciclib (AC) is a novel, orally available drug molecule approved for the treatment of breast cancer. Due to its low bioavailability, its administration frequency is two to three times a day that can decrease patient compliance. Sustained release formulation are needed for prolong the action and to reduce the adverse effects. The aim of current study was to develop sustained release NSs of AC. Nanosponges (NSs) was prepared by emulsion-solvent diffusion method using ethyl-cellulose (EC) and Kolliphor P-188 (KP-188) as sustained-release polymer and surfactant, respectively. Effects of varying surfactant concentration and drug: polymer proportions on the particle size (PS), polydispersity index (PDI), zeta potential (ζP), entrapment efficiency (%EE), and drug loading (%DL) were investigated. The results of AC loaded NSs (ACN1-ACN5) exhibited PS (366.3–842.2 nm), PDI (0.448–0.853), ζP (−8.21 to −19.7 mV), %EE (48.45–79.36%) and %DL (7.69–19.17%), respectively. Moreover, ACN2 showed sustained release of Abemaciclib (77.12 ± 2.54%) in 24 h Higuchi matrix as best fit kinetics model. MTT assay signified ACN2 as potentials cytotoxic nanocarrier against MCF-7 and MDA-MB-231 human breast cancer cells. Further, ACN2 displayed drug release property without variation in the % release after exposing the product at 25 °C, 5 °C, and 45 °C storage conditions for six months. This investigation proved that the developed NSs would be an efficient carrier to sustain the release of AC in order to improve efficacy against breast cancer.

A Randomized Phase I Study of Abemaciclib in Chinese Patients with Advanced and/or Metastatic Cancers

Background

Abemaciclib, a cyclin-dependent kinase 4 and 6 inhibitor, is approved in combination with endocrine therapy or as monotherapy for hormone receptor-positive and human epidermal growth factor receptor-2-negative (HR+/HER2−) advanced breast cancer outside of China.

Objective

To evaluate the safety, tolerability, and pharmacokinetic (PK) profile of abemaciclib in Chinese patients with advanced and/or metastatic cancers.

Patients and methods

A multicenter, open-label, phase I trial of abemaciclib in Chinese patients with advanced and/or metastatic cancers was conducted. Patients were randomized (1:1) to oral abemaciclib 150 or 200 mg every 12 h on a 28-day cycle. Safety analyses (primary outcome) included all patients receiving at least one dose of abemaciclib. PK and antitumor activity were also assessed.

Results

Of the 26 patients randomized, 25 received abemaciclib 150 mg (n = 12) or 200 mg (n = 13). All 25 patients reported ≥ 1 treatment-emergent adverse event (TEAE). The majority of TEAEs were Common Terminology Criteria for Adverse Events (CTCAE) Grade 1 or 2 in severity. The most frequent TEAEs of Grade ≥ 3 were neutropenia (32%) and thrombocytopenia (24%). Four patients (16%) discontinued treatment due to AEs. Abemaciclib exhibited slow absorption and clearance at single dose, with maximum concentrations achieved after around 6 h and an elimination half-life of approximately 24 h. No complete response was observed, two patients (8%) achieved partial response, with one confirmed responder, and the disease control rate was 68% (n = 17).

Conclusions

Abemaciclib was well tolerated and the safety and PK profiles in Chinese patients were comparable to those previously reported in non-Chinese populations. Preliminary antitumor activity was observed.

ClinicalTrials.gov identifier

NCT02919696.

Abemaciclib: safety and effectiveness of a unique cyclin-dependent kinase inhibitor

INTRODUCTION

The discovery and the clinical availability of novel cyclin-dependent kinases 4 and 6 inhibitors have profoundly changed the therapeutic scenario of metastatic hormone receptor-positive breast carcinoma. Among these inhibitors, abemaciclib can induce potent and sustained cell cycle arrest and immune system stimulation.

AREAS COVERED

This review summarizes the safety profile and clinical efficacy data on abemaciclib alone or in combination with aromatase inhibitors or fulvestrant in metastatic hormone receptor-positive breast carcinoma. The management of patients treated with abemaciclib is the object of this paper.

EXPERT OPINION

As shown in phase 2 and 3 clinical trials on efficacy and tolerability, abemaciclib is a potentially convenient, safe, and effective agent for the treatment of patients with advanced hormone receptor-positive patients. Orally administered abemaciclib in combination with aromatase inhibitors or fulvestrant has the potential to allow significant improvement in survival outcomes, quality of life, response rate, and duration of response even in poor prognosis subgroups. Adequate patients' information, clinical selection, and prompt, proactive management of side effects are mandatory.

Male patient with metastatic stage IV breast cancer achieves complete remission on second line Abemaciclib, Fulvestrant and Leuprolide: A case report

Male breast cancer occurs rarely, comprising <1% of breast cancers. Due to the low incidence of male breast cancer, clinical trials of this disease are lacking. Therefore, therapeutic strategies utilized in the management of female breast cancer are often applied to male patients with breast cancer. Specifically, clinical outcomes using CDK 4/6 inhibitors require further investigation in male patients. To the best of our knowledge, the present report presents the first known case of a male patient treated with second line Abemaciclib, Lupron and Fulvestrant, producing complete remission. To the best of our knowledge this is also the first report of complete remission in a male breast cancer patient with a regimen utilizing a CDK 4/6 inhibitor.

A current and comprehensive review of cyclin-dependent kinase inhibitors for the treatment of metastatic breast cancer

BACKGROUND

Resistance to endocrine treatment generally occurs over time, especially in the metastatic stage. In this paper, we aimed to review the mechanisms of cyclin-dependent kinase (CDK) 4/6 inhibition and clinical usage of new agents in the light of recent literature updates.

SCOPE

A literature search was carried out using PubMed, Medline and ASCO and ESMO annual-meeting abstracts by using the following search keywords; "palbociclib", "abemaciclib", "ribociclib", "cyclin-dependent kinase inhibitors" and "CDK 4/6" in metastatic breast cancer (MBC). The last search was on 10 June 2017.

FINDINGS

CDKs and cyclins are two molecules that have a key role in cell cycle progression. Today, there are three highly selective CDK4/6 inhibitors in clinical development - palbociclib, ribociclib and abemaciclib. Palbociclib and ribociclib were recently approved by the US FDA in combination with letrozole for the treatment of MBC in a first-line setting, as well as palbociclib in combination with fulvestrant for hormone-receptor (HR)-positive MBC that had progressed while on previous endocrine therapy according to the PALOMA-1, MONALEESA-2 and PALOMA-3 trials, respectively. In the recently published randomized phase III MONARCH 2 trial, abemaciclib plus letrozole had longer progression-free survival and higher objective response rates with less serious adverse events in advanced HR-positive breast cancer previously treated with hormonal treatment.

CONCLUSION

CDK4/6 inhibition is a new and promising target for patients with hormone-receptor-positive MBC. Both palbociclib and ribociclib showed significant additive benefit for patients receiving first-line treatment for HR-positive, epidermal growth factor receptor-2-negative advanced breast cancer. Palbociclib and abemaciclib also had significant activity in combination with fulvestrant for patients with MBC that progressed on previous endocrine therapy.

MONARCH 2: Abemaciclib in Combination With Fulvestrant in Women With HR+/HER2− Advanced Breast Cancer Who Had Progressed While Receiving Endocrine Therapy

Purpose

MONARCH 2 ( ClinicalTrials.gov identifier: NCT02107703) compared the efficacy and safety of abemaciclib, a selective cyclin-dependent kinase 4 and 6 inhibitor, plus fulvestrant with fulvestrant alone in patients with advanced breast cancer (ABC).

Patients and Methods

MONARCH 2 was a global, double-blind, phase III study of women with hormone receptor-positive and human epidermal growth factor receptor 2-negative ABC who had progressed while receiving neoadjuvant or adjuvant endocrine therapy (ET), ≤ 12 months from the end of adjuvant ET, or while receiving first-line ET for metastatic disease. Patients were randomly assigned 2:1 to receive abemaciclib or placebo (150 mg twice daily) on a continuous schedule and fulvestrant (500 mg, per label). The primary end point was investigator-assessed progression-free survival (PFS), and key secondary end points included overall survival, objective response rate (ORR), duration of response, clinical benefit rate, quality of life, and safety.

Results

Between August 2014 and December 2015, 669 patients were randomly assigned to receive abemaciclib plus fulvestrant (n = 446) or placebo plus fulvestrant (n = 223). Abemaciclib plus fulvestrant significantly extended PFS versus fulvestrant alone (median, 16.4 v 9.3 months; hazard ratio, 0.553; 95% CI, 0.449 to 0.681; P < .001). In patients with measurable disease, abemaciclib plus fulvestrant achieved an ORR of 48.1% (95% CI, 42.6% to 53.6%) compared with 21.3% (95% CI, 15.1% to 27.6%) in the control arm. The most common adverse events in the abemaciclib versus placebo arms were diarrhea (86.4% v 24.7%), neutropenia (46.0% v 4.0%), nausea (45.1% v 22.9%), and fatigue (39.9% v 26.9%).

Conclusions

Abemaciclib at 150 mg twice daily plus fulvestrant was effective, significantly improving PFS and ORR and demonstrating a tolerable safety profile in women with hormone receptor-positive and human epidermal growth factor receptor 2-negative ABC who progressed while receiving ET.