Cell-Cycle Therapeutics Come of Age

Incorporating CDK4/6 Inhibitors in the Treatment of Advanced Luminal Breast Cancer

After optimizing endocrine monotherapy modalities in the setting of advanced luminal breast cancer (BC), dual endocrine/targeted therapy combinations have been tested with positive results, and are transforming this BC subtype treatment landscape. Cell cycle deregulation is a hallmark of cancer that has become a key druggable target in hormone receptor (HR)-positive BC due to its role in endocrine resistance mechanisms. Cyclin dependent kinase (CDK)4/6 inhibitors have experienced a fast development in combination with endocrine therapy and have already been commercialized in some countries. In this review, we will summarize the development of these CDK4/6 inhibitors in luminal BC, from the preclinical data to the pivotal phase III trials that led to their approval, focusing on the efficacy and safety data for each of the treatment settings. Moreover, we will consider the challenges CDK4/6 inhibitors face in their positioning in the algorithm of treatment for advanced luminal BC and the considerations physicians should take into account when selecting these therapies for their patients. However, we are still in need of reliable predictive biomarkers in order to identify patients who will derive the greatest benefit from these drug combinations that are not exempt from toxicity.

A Young Female Athlete With Acute Low Back Pain Caused by Stage IV Breast Cancer

OBJECTIVE

The purpose of this case report is to describe the case of a young female athlete with low back pain caused by metastatic breast cancer.

CLINICAL FEATURES

A 27-year-old woman presented with low back pain after striking a ball during kickball 3 days earlier. Because of the mechanism of injury and onset, the patient was originally diagnosed with a lumbar spine sprain/strain.

INTERVENTION/OUTCOME

After radiographs were obtained and were read as unremarkable, a 2-week trial of care was initiated that included soft-tissue mobilizations, anti-inflammatory medications from her primary care physician, and therapeutic rehabilitation exercises. After this trial concluded, the patient did not improve and continued to be in significant pain. Magnetic resonance imaging was then ordered and revealed an expansile lesion at L2 with cortical compromise. Referral to an oncologist prompted the diagnosis of stage IV breast cancer.

CONCLUSION

Poor response to conservative treatment may indicate the working diagnosis is incorrect and that it must be reconsidered. In this case, a lack of response to care with persistent high severity of pain despite a multimodal approach justified further investigation with advanced imaging, which revealed spinal metastases secondary to breast cancer. Clinicians should be aware of history and physical exam indicators of red flag conditions that may present as low back pain.