Efficacy and Safety of Cyclin-Dependent Kinases 4 and 6 Inhibitors in HR+/HER2- Advanced Breast Cancer

Adverse Cardiovascular Events Associated With Cyclin-Dependent Kinase 4/6 Inhibitors in Patients With Metastatic Breast Cancer

Background Cyclin-dependent kinase (CDK) 4 and 6 inhibitors have significantly improved survival in patients with hormone receptor-positive metastatic breast cancer. There are few data regarding the epidemiology of cardiovascular adverse events (CVAEs) with these therapies. Methods and Results Using the OneFlorida Data Trust, adult patients without prior cardiovascular disease who received at least 1 CDK4/6 inhibitor were included in the analysis. CVAEs identified from International Classification of Diseases, Ninth and Tenth Revisions (ICD-9/10) codes included hypertension, atrial fibrillation(AF)/atrial flutter (AFL), heart failure/cardiomyopathy, ischemic heart disease, and pericardial disease. Competing risk analysis (Fine-Gray model) was used to determine the association between CDK4/6 inhibitor therapy and incident CVAEs. The effect of CVAEs on all-cause death was studied using Cox proportional hazard models. Propensity-weight analyses were performed to compare these patients to a cohort of patients treated with anthracyclines. A total of 1376 patients treated with CDK4/6 inhibitors were included in the analysis. CVAEs occurred in 24% (35.9 per 100 person-years). CVAEs were slightly higher in patients who received CKD4/6 inhibitors compared with anthracyclines (P=0.063), with higher death rate associated with the development of AF/AFL or cardiomyopathy/heart failure in the CDK4/6 group. The development of cardiomyopathy/heart failure and AF/AFL was associated with increased all-cause death (adjusted hazard ratio [HR], 4.89 [95% CI, 2.98-8.05]; and 5.88 [95% CI, 3.56-9.73], respectively). Conclusions CVAEs may be more common with CDK4/6 inhibitors than previously recognized, with increased death rates in these patients who develop AF/AFL or heart failure. Further research is needed to definitively determine cardiovascular risk associated with these novel anticancer treatments.

Cost Effectiveness of Ribociclib and Palbociclib in the Second-Line Treatment of Hormone Receptor-Positive, HER2-Negative Metastatic Breast Cancer in Post-Menopausal Indian Women

BACKGROUND

In this study, we evaluate the cost and outcomes of cyclin-dependent kinase 4/6 inhibitors (CDK4/6i) plus fulvestrant, fulvestrant alone, and conventional chemotherapy as the second-line therapy for hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) metastatic breast cancer (MBC) in India.

METHODS

Using a Markov model, the clinical effectiveness of managing HR+, HER2- MBC in postmenopausal women with either a CDK4/6i (either ribociclib or palbociclib) and fulvestrant, fulvestrant alone, and chemotherapy (single-agent paclitaxel or capecitabine) was measured in terms of quality-adjusted life-years (QALYs). The costs were estimated from two different points of view: scenario I, as per the prevailing market prices of the drugs; and scenario II, as per the reimbursement rates set up by the publicly financed national health insurance scheme. Incremental cost per QALY gained with a given treatment option was compared against the next best alternative and was assessed for cost effectiveness using a threshold of 1-time the per capita gross domestic product (GDP) in India from a societal perspective.

RESULTS

In scenario I, an MBC patient was found to incur a lifetime cost of Indian Rupees (₹) 2.54 million ($34,644), ₹2.53 million ($34,496), ₹512,598 ($6,984), ₹326,026 ($4,442) and ₹237,115 ($3,230) for the ribociclib and palbociclib combination arms, fulvestrant monotherapy, single-agent paclitaxel and the single-agent capecitabine treatment arms, respectively. The lifetime cost for CDK4/6i (ribociclib and palbociclib) combination therapy, fulvestrant monotherapy, paclitaxel, and capecitabine arms was estimated to be ₹1.94 million ($26,459), ₹1.92 million ($26,220), ₹315,387 ($4,296), ₹187,392 ($2,553) and ₹153,263 ($2,088), respectively, in scenario II. The mean QALYs lived per MBC patient with CDK4/6i (either ribociclib or palbociclib) combination therapy, fulvestrant, paclitaxel and capecitabine were estimated to be 1.4, 1.0, 0.9 and 0.7, respectively. None of the treatment arms are cost effective at current prices and reimbursement rates at a threshold of 1-time the per capita GDP of India. However, a 78% reduction in the current market price or a 72% reduction in the reimbursement rate of fulvestrant in the government-funded insurance program will make it a cost-effective treatment option for HR+, HER2- MBC patients in India.

CONCLUSION

CDK4/6i (ribociclib and palbociclib) therapy is not a cost-effective treatment option for MBC patients. A 72% reduction in the reimbursement rate for fulvestrant monotherapy will make it a cost-effective treatment option in the Indian context.

Clinical Utility of CDK4/6 Inhibitors in Sarcoma: Successes and Future Challenges

PURPOSE

Soft tissue and bone sarcomas are rare malignancies that exhibit significant pathologic and molecular heterogeneity. Deregulation of the CDKN2A-CCND-CDK4/6-retinoblastoma 1 (Rb) pathway is frequently observed in about 25% of unselected sarcomas and is pathognomonic for specific sarcoma subtypes. This genomic specificity has fueled the clinical evaluation of selective CDK4/6 inhibitors in sarcomas. Here, we highlight successes, opportunities, and future challenges for using CDK4/6 inhibitors to treat sarcoma.

MATERIALS AND METHODS

This review summarizes the current evidence for the use of CDK4/6 inhibitors in sarcoma while identifying molecular rationale and predictive biomarkers that provide the foundation for targeting the CDK4/6 pathway in sarcoma. A systematic review was performed of articles indexed in the PubMed database and the National Institutes of Health Clinical Trials Registry (ClinicalTrials.gov). For each sarcoma subtype, we discuss the preclinical rationale, case reports, and available clinical trials data.

RESULTS

Despite promising clinical outcomes in a subset of sarcomas, resistance to CDK4/6 inhibitors results in highly heterogeneous clinical outcomes. Current clinical data support the use of CDK4/6 inhibitors in subsets of sarcoma primarily driven by CDK4/6 deregulation. When dysregulation of the Rb pathway is a secondary driver of sarcoma, combination therapy with CDK4/6 inhibition may be an option. Developing strategies to identify responders and the mechanisms that drive resistance is important to maximize the clinical utility of these drugs in patients with sarcoma. Potential biomarkers that indicate CDK4/6 inhibitor sensitivity in sarcoma include CDK4, CCND, CCNE, RB1, E2F1, and CDKN2A.

CONCLUSION

CDK4/6 inhibitors represent a major breakthrough for targeted cancer treatment. CDK4/6 inhibitor use in sarcoma has led to limited, but significant, early clinical success. Targeted future clinical research will be key to unlocking the potential of CDK4/6 inhibition in sarcoma.

Response to CDK4/6-inhibitors in sarcomas indicate the need for predictive biomarkers specific to this disease.

Real-world effectiveness and sensitivity of palbociclib plus endocrine therapy in HR+/HER2- patients with metastatic breast cancer

Palbociclib has shown satisfactory outcomes when combined with endocrine therapy (ET) in hormone receptor-positive and human epidermal growth factor receptor 2-negative (HR+/HER2-) metastatic breast cancer (MBC). However, data in Asia are currently scarce.This retrospective study aimed to evaluate the real-world effectiveness, sensitivity, and toxicity of palbociclib plus ET in HR+/HER2- MBC in North China. We recruited patients with HR+/HER2- MBC from August 2018 to July 2020 across 7 hospitals in North China. The primary endpoint was to evaluate progression-free survival (PFS) after initial progress on palbociclib therapy. The secondary endpoints included determining predictive biomarkers of palbociclib sensitivity and toxicity of palbociclib.A total of 54 patients were analyzed in this cohort with an estimated median follow-up time of 14.3 months. Patients who received palbociclib as a first-line treatment showed significantly prolonged PFS compared with those who received palbociclib as a second-line or beyond treatment (21.8 months vs 15.9 months vs 6.8 months) (P < .001). Besides, patients with Ki67 <30% (P = .024) and PR ≥20% (P = .041) in metastatic tumors had significantly longer PFS. The Cox proportional-hazards regression analyses proved that different lines (P = .001 in multivariate analysis), Ki67 <30% (P = .035 in multivariate analysis), and PR ≥20% (P = .045 in univariate analysis) in metastatic tumors affected PFS significantly. The most common adverse events were hematologic, with 31.48% of patients having neutropenia.Palbociclib plus ET significantly prolonged PFS for patients with HR+/HER2- MBC who received first-line therapy, with manageable toxicity. The values of Ki67 and PR in metastatic tumors may be potential predictive biomarkers of palbociclib sensitivity.

The Place of Chemotherapy in The Evolving Treatment Landscape for Patients With HR-positive/HER2-negative MBC

Endocrine therapy (ET) for the treatment of patients with hormone receptor-positive/human epidermal growth factor receptor 2-negative (HR-positive/HER2-negative) metastatic breast cancer (MBC) has changed markedly over recent years with the emergence of new ETs and the use of molecularly targeted agents. Cytotoxic chemotherapy continues, however, to have an important role in these patients and it is important to maximize its efficacy while minimizing toxicity to optimize outcomes. This review examines current HR-positive/HER2-negative MBC clinical guidelines and addresses key questions around the use of chemotherapy in the face of emerging therapeutic options. Specifically, the indications for chemotherapy in patients with HR-positive/HER2-negative MBC and the choice of optimal chemotherapy are discussed.

Breast cancer liver metastasis: current and future treatment approaches

Nearly all fatalities arising from breast tumors are attributable to distant metastases. Breast cancer liver metastasis (BCLM) is associated with poor prognoses, with the median survival time being 2 to 3 years. Tumor intrinsic subtype directs preferential metastasis to specific organs, with HER2-enriched tumors demonstrating the highest rates of metastasis to the liver, though all subtypes can grow in the liver. There is no singular established standard-of-care for BCLM; therapeutic selection is driven by histologic and molecular hallmarks of the primary tumor or biopsied metastasis samples. Given the poor prognosis of patients with hepatic spread, pre-clinical studies are necessary to identify and evaluate promising new treatment strategies. It is critical that these laboratory studies accurately recapitulate the BCLM disease process, standard progression, and histological attributes. In this review, we summarize the histologic and molecular characteristics of BCLM, evaluate the efficacy of existing surgical and medical treatment strategies, and discuss future approaches to preclinical study of BCLM.