Does the Rechallenge with Another CDK 4/6 Inhibitor in Breast Cancer Work? A Case Report and Literature Review.

Cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors and endocrine therapy are the gold standards for systemic therapy for patients with hormone-positive (HR+)/human epidermal growth factor receptor-2-negative (HER2-) metastatic breast cancer. Following progression, no prospective randomized data exist to help guide second-line treatment. Moreover, there is a scarcity of data on rechallenge treatment strategies with another CDK4/6 inhibitor after prior limiting toxicity. We report a real-world experience of rechallenging with abemaciclib after the prior reaction of grade 4 liver toxicity to ribociclib, with high transaminases values of more than 27 times the upper limit of normal (ULN) and unexpected grade 3 neutropenia and diarrhea after a few months of abemaciclib. After two years of treatment, the patient had stable oncological disease, with normal complete blood count, hepatic enzymes, and a very good performance status. We believe that our clinical case, along with others gathered from all around the world, will help with the consolidation of an unmet clinical need to readjust the treatment after experiencing toxicity to CDK4/6 inhibitors.

Mechanisms of Resistance to CDK4/6 Inhibitors and Predictive Biomarkers of Response in HR+/HER2-Metastatic Breast Cancer-A Review of the Literature.

The latest and newest discoveries for advanced and metastatic hormone receptor-positive (HR+) and human epidermal growth factor receptor 2-negative (HER2-) breast cancer are the three cyclin-dependent kinases 4 and 6 inhibitors (CDK4/6i) in association with endocrine therapy (ET). However, even if this treatment revolutionized the world and continued to be the first-line treatment choice for these patients, it also has its limitations, caused by de novo or acquired drug resistance which leads to inevitable progression after some time. Thus, an understanding of the overview of the targeted therapy which represents the gold therapy for this subtype of cancer is essential. The full potential of CDK4/6i is yet to be known, with many trials ongoing to expand their utility to other breast cancer subtypes, such as early breast cancer, and even to other cancers. Our research establishes the important idea that resistance to combined therapy (CDK4/6i + ET) can be due to resistance to endocrine therapy, to treatment with CDK4/6i, or to both. Individuals' responses to treatment are based mostly on genetic features and molecular markers, as well as the tumor's hallmarks; therefore, a future perspective is represented by personalized treatment based on the development of new biomarkers, and strategies to overcome drug resistance to combinations of ET and CDK4/6 inhibitors. The aim of our study was to centralize the mechanisms of resistance, and we believe that our work will have utility for everyone in the medical field who wants to deepen their knowledge about ET + CDK4/6 inhibitors resistance.

The Prognostic Value of Neutrophil-to-Lymphocyte Ratio in Patients with Metastatic Renal Cell Carcinoma.

BACKGROUND: Metastatic renal cell carcinoma (mRCC) is an aggressive cancer characterised by an increased recurrence rate and an inadequate response to treatment. This study aimed to investigate the importance of the neutrophil-to-lymphocyte ratio (NLR) as a prognostic marker for long-term survival in patients with mRCC. METHODS: We retrospectively analysed data from 74 patients with mRCC treated at our medical centre with tyrosine kinase inhibitors (TKIs) and immune checkpoint inhibitors (ICIs). We evaluated the predictive value of NLR for overall survival (OS) in these patients. RESULTS: The median OS was 5.1 months in the higher NLR group (≥3) and 13.3 months in the lower NLR group (<3) (p < 0.0001). There was no significant difference in the OS between the TKI and ICI therapies in the low NLR group (12.9 vs. 13.6 months, p = 0.411) or in the high NLR group (4.7 vs. 5.5 months, p = 0.32). Both univariate and multivariate analyses revealed that a higher NLR was an independent prognostic factor of long-term survival in patients with mRCC treated with first-line therapy. CONCLUSIONS: This retrospective study showed that adding NLR to other Memorial Sloan Kettering Cancer Center (MSKCC) and International Metastatic Renal Cell Carcinoma Database Consortium (IMDC) variables might improve the prognostic and predictive power of these models.