Innovative Therapy for Patients with Brain Metastases: Oral Treatments

Management of ER positive metastatic breast cancer

There are over 2 million cases a year of breast cancer, leading to over 600,000 deaths globally [1]. Despite these large numbers, increasingly more women are being cured with early stage disease and women with advanced disease are living longer [2]. The appreciation for molecular subtypes of the disease has led to significant therapeutic advances and estrogen receptor positive (ER+) breast cancer represents the largest of these subgroups. An appreciation for the importance of estrogen signaling in ER+ dates back to 1896 when Dr. George Thomas Beatson observed impressive disease responses after performing bilateral oophorectomy in 3 women at Glasgow Cancer Hospital [3]. The evolution of treatment for advanced disease from progestins, to the selective estrogen receptor modulator tamoxifen, and subsequently the aromatase inhibitors and the selective estrogen receptor degrader fulvestrant, has been accompanied by improved efficacy and decreased side effects. While the use of these drugs has changed the natural history of both early and advanced disease, it has been long recognized that many patients will develop resistance to this approach. After many years of trying to improve on single-agent endocrine treatment, since 2012 there has been an explosion of new drugs that have shown improved efficacy in combination with endocrine approaches. The first of these to receive FDA approval was the mTOR inhibitor everolimus (2012) [4], followed by the approval of 3 cyclin-dependent kinase 4 and 6 (CDK 4/6) inhibitors [palbociclib (2015) [5], ribociclib (2018) [6], and abemaciclib (2018) [7]], and more recently the PI3-kinase inhibitor alpelisib (2019) [8]. In addition, chemotherapy is still used frequently when endocrine manipulations have been exhausted. Like other incurable malignancies, the goal in advanced ER+ breast cancer is to prolong survival and maintain quality of life. Currently, we have more tools available to achieve this than ever before and we will review the efficacy and side effect data with these agents that are driving physician choices for individual patients.

Tumor bed radiosurgery following resection and prior stereotactic radiosurgery for locally persistent brain metastasis

PURPOSE

Despite advances in multimodality management of brain metastases, local progression following stereotactic radiosurgery (SRS) can occur. Often, surgical resection is favored, as it frequently provides immediate symptom relief as well as pathological characterization of any residual tumor. Should the pathological specimen contain viable tumor cells, further radiation therapy is an option to sterilize the tumor bed. We evaluated the use of repeat SRS (rSRS) in lieu of whole-brain radiation therapy (WBRT) as a means of improving local control (LC) while minimizing potential toxicity and dose to the normal brain.

MATERIALS/METHODS

A retrospective review was performed to identify patients with brain metastases who underwent SRS and then surgical resection for locally recurrent or persistent disease. From 2004 to 2014, 13 consecutive patients or 15 lesions were treated with rSRS after resection, either post-operatively to the tumor bed (n = 10, 66.6%) or after a second local recurrence (n = 5, 33.3%). LC, distant brain failure (DBF), and radiation toxicity were determined using patient records, RECIST criteria v1.1, and CTCAE v4.03.

RESULTS

At a median follow-up interval of 9.0 months (range 1.8-54.9 months) from time of rSRS, five patients remain alive. Following rSRS, 13 of the 15 (86.6%) lesions were locally controlled with an estimated 100% LC at 6 months and 75% LC at 1 year. However, 11 of the 15 (73.3%) treated lesions developed DBF after rSRS with 3 of 13 patients proceeding to WBRT. Two of 15 (13.3%) resulted in either grade 2 radionecrosis with grade 3 seizures or grade 3 radionecrosis.

CONCLUSION

Repeat SRS represents a potential salvage therapy for patients with locally recurrent brain metastases, providing additional tumor control with acceptable toxicity, even in the setting of prior SRS and surgical resection. rSRS may be reasonable to use as an alternative to WBRT in this setting.

ACR Appropriateness Criteria® follow-up and retreatment of brain metastases

Multiple options for retreatment are available, which include whole-brain radiation therapy, stereotactic radiosurgery, surgery, chemotherapy, and supportive care. Size, number, timing, location, histology, performance status, and extracranial disease status all need to be carefully considered when choosing a treatment modality. There are no randomized trials examining the retreatment of brain metastases. Repeat whole-brain radiation has been examined in a single-institution experience, showing the potential for clinical responses in selected patients. Local control rates as high as 91% using stereotactic radiosurgery for relapses after whole-brain radiation are reported. Surgery can be indicated in progressive and/or hemorrhagic lesions causing mass effect. The role of chemotherapy in the recurrent setting is limited but some agents may have activity on the basis of experiences on a smaller scale. Supportive care continues to be an important option, especially in those with a poor prognosis. Follow-up for brain metastases patients is discussed, examining the modality, frequency of imaging, and imaging options in differentiating treatment effect from recurrence. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 2 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of the current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In instances where evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

Central nervous system metastases in HER-2-overexpressing metastatic breast cancer: a treatment challenge

With improvements in diagnostic and therapeutic options and a corresponding improvement in survival, central nervous system (CNS) metastasis is becoming a more frequent diagnosis in breast cancer patients. It can be assumed that up to 30% of metastatic breast cancer (MBC) patients may experience CNS metastasis during the course of their disease. Moreover, it has been reported that patients with human epidermal growth factor receptor (HER)-2-overexpressing MBC are at a higher risk for CNS involvement. Whereas locoregional treatment modalities such as surgery, radiosurgery, and whole-brain radiotherapy still must be considered as the treatment of first choice, the armamentarium of systemic treatment modalities has been expanded by the introduction of small molecules such as the tyrosine kinase inhibitors. Rather than analyzing the risk factors for the development of CNS metastasis and reviewing the standard diagnostic and therapeutic approaches in patients with CNS involvement, this review focuses specifically on systemic treatment modalities in patients suffering from CNS metastasis from HER-2-overexpressing MBC.