Therapy after cyclin-dependent kinase inhibition in metastatic hormone receptor-positive breast cancer: Resistance mechanisms and novel treatment strategies.

Endocrine therapy has been the standard of care for patients with metastatic hormone receptor (HR)-positive, HER2-negative breast cancer since the 1970s, improving survival while avoiding the toxicities associated with cytotoxic chemotherapy. However, all HR-positive tumors ultimately develop resistance to endocrine therapy. Cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors have more recently become an important component of the management of this breast cancer subtype, significantly delaying time to the disease progression and improving survival when combined with endocrine therapy. However, as with endocrine therapy alone, treatment resistance remains a universal phenomenon. As more women receive CDK4/6 inhibitors as part of their treatment, the management of de novo and acquired resistance to combined CDK4/CDK6 inhibitor plus endocrine therapy regimens has emerged as an important clinical challenge. Several resistance mechanisms have been described, including alterations in the CDK4/6/cyclin D complex or its major effector retinoblastoma protein (pRb), bypass signaling through other cyclin/CDK complexes and activation of upstream signaling pathways, in particular the PI3K/mTOR pathway, but robust biomarkers to predict resistance remain elusive, and the role for continuing CDK4/6 inhibitors after progression remains under investigation. Novel strategies being evaluated in clinical trials include the continuation of CDK4/6 inhibitors through progression, as well as triplet therapy combinations with PI3K inhibitors or immune checkpoint inhibitors.

Molecular Assays to Determine Optimal Duration of Adjuvant Endocrine Therapy in Breast Cancer.

OPINION STATEMENT: Hormone receptor (HR) positive breast cancer has a high propensity for late recurrences that might be prevented with longer durations of endocrine therapy (ET). However, trials evaluating extended adjuvant ET have produced somewhat conflicting results. Additionally, ET is associated with not only day to day side effects that can impact quality of life, but more detrimental effects that can cause significant morbidity. Although patients with higher stage disease are at greater risk of late recurrences, even patients with stage 1 disease have a significant risk of recurrence after 5 years. Current guidelines recommend extending therapy for patients with node-positive disease, but recommendations for patients with node-negative disease are less clear. This has led to the development of various genomic tests to aid oncologists in further individualizing their approach when it comes to deciding which subpopulation of patients with HR-positive breast cancer may benefit from extending their endocrine therapy beyond 5 years. There are several assays that are prognostic of recurrences years 6 to 10 following diagnosis. Additionally, the breast cancer index has been shown to be predictive of extended ET in patients who have completed 5 years of tamoxifen. None of the available assays are, to date, predictive of recurrence after 10 years. Genomic testing is not appropriate for all patients, especially if the results will not predict the choice of further treatment. Ultimately, genomic testing should help facilitate shared decision making between the patient and oncologist.

Serum electrolyte dynamics in multiple myeloma patients undergoing autologous haematopoietic stem cell transplantation.

AIM: High-dose melphalan followed by autologous haematopoietic cell transplantation remains the standard-of-care therapy for multiple myeloma (MM). Gastrointestinal toxicity concomitant with electrolyte derangement is a primary cause of morbidity from transplant. Here, we assessed the dynamics of electrolyte imbalances and its role in hematologic counts and engraftment. Ω Patients and Methods One hundred and eighteen MM patients that received transplant were studied. RESULTS: Engraftment speed (ES) was calculated as the period between the first rise in the absolute neutrophil count (ANC) and full engraftment defined as the first of three consecutive days with ANC > 500 × 106 /L. The defined median ES was 2 days (range 0-5 days) and 40 patients had ES ≤2 days. Engraftment occurred at a median of 10 days. The median time-to-nadir for phosphorus and potassium was 10 and 4.28 days, respectively. The drop in phosphorus and potassium serum level was statistically greater in patients with an ES ≤2 days compared to patients with ES ≥2 days. Magnesium level were not significantly affected and there was no significant difference between the drop in serum phosphorus and potassium based on severity of nausea or oral mucositis. CONCLUSION: Our results indicate that there is a significant correlation between the magnitude of drop in potassium and phosphorous levels and a steep rise in neutrophil counts around the engraftment period following stem cell transplant. These events indicate a "genesis syndrome" characterized by a rapid, massive transfer of electrolytes into proliferating cells as has been previously described after HCT for certain high-grade lymphomas and leukemias.

Disparities in Treatment Satisfaction and Supportive Care Receipt for Young Adult Oncology Patients on the Basis of Residential Location.

PURPOSE: Adolescent and young adult oncology programs are critical but exist primarily in academic centers, prompting potential disparities in care on the basis of patient residence. We studied the impact of residential location on supportive care receipt and treatment satisfaction in young adults (YAs) with cancer age 19-39 years treated at the University of Wisconsin Carbone Cancer Center (UWCCC). METHODS: YA patients with cancer age 19-39 years seen at UWCCC from March 30, 2019, to March 29, 2020, were sent a survey assessing supportive care receipt and satisfaction. Survey results were compared with retrospective chart review of YAs seen at UWCCC between April 1, 2011, and April 1, 2021. Data were categorized on the basis of residential location using distance from UWCCC and 2013 Rural-Urban Continuum Code (RUCC). RESULTS: Survey results were obtained for 145 YAs, including 29 from nonmetro RUCC (20.0%) and 81 living > 20 miles from UWCCC (55.9%). YAs from nonmetro locations had lower satisfaction with available treatments (79.3% v 91.4%, P = .005), and distant YAs living > 20 miles from UWCCC more frequently identified location as a barrier to supportive care receipt (35.6% v 15.8%, P = .02). Metro YAs more frequently listed fertility consultations as unavailable (38.0% v 16.0%, P = .04) in the survey despite chart review data showing higher rates of sexual health assessments (48.2% v 20.4%, P = .002) and fertility visits (29.6% v 18.5%, P = .18). CONCLUSION: We identified differences in both supportive care receipt and treatment satisfaction on the basis of residential location. These findings support the need for measures to successfully meet treatment and supportive care needs regardless of residential location.