Local therapies for brain metastases, competing risks, and overall survival

The effect of timing of stereotactic radiosurgery treatment of melanoma brain metastases treated with ipilimumab

OBJECTIVE

Melanoma represents the third most common cause of CNS metastases. Immunotherapy has evolved as a treatment option for patients with Stage IV melanoma. Stereotactic radiosurgery (SRS) also elicits an immune response within the brain and may interact with immunotherapy. The authors report on a cohort of patients treated for brain metastases with immunotherapy and evaluate the effect of SRS timing on the intracranial response.

METHODS

All consecutively treated melanoma patients receiving ipilimumab and SRS for treatment of brain metastases at the University of Virginia between 2009 and 2014 were included in this retrospective analysis; data from 46 patients harboring 232 brain metastases were reviewed. The median duration of clinical follow-up was 7.9 months (range 3–42.6 months). The median age of the patients was 63 years (range 24.3–83.6 years). Thirty-two patients received SRS before or during ipilimumab cycles (Group A), whereas 14 patients received SRS after ipilimumab treatment (Group B). Radiographic and clinical responses were assessed at approximately 3-month intervals after SRS.

RESULTS

The 2 cohorts were comparable in pertinent baseline characteristics with the exception of SRS timing relative to ipilimumab. Local recurrence–free duration (LRFD) was significantly longer in Group A (median 19.6 months, range 1.1–34.7 months) than in Group B patients (median 3 months, range 0.4–20.4 months) (p = 0.002). Post-SRS perilesional edema was more significant in Group A.

CONCLUSIONS

The effect of SRS and ipilimumab on LRFD seems greater when SRS is performed before or during ipilimumab treatments. The timing of immunotherapy and SRS may affect LRFD and postradiosurgical edema. The interactions between immunotherapy and SRS warrant further investigation so as to optimize the therapeutic benefits and mitigate the risks associated with multimodality, targeted therapy.

Updates in the management of brain metastases

The clinical management/understanding of brain metastases (BM) has changed substantially in the last 5 years, with key advances and clinical trials highlighted in this review. Several of these changes stem from improvements in systemic therapy, which have led to better systemic control and longer overall patient survival, associated with increased time at risk for developing BM. Development of systemic therapies capable of preventing BM and controlling both intracranial and extracranial disease once BM are diagnosed is paramount. The increase in use of stereotactic radiosurgery alone for many patients with multiple BM is an outgrowth of the desire to employ treatments focused on local control while minimizing cognitive effects associated with whole brain radiotherapy. Complications from BM and their treatment must be considered in comprehensive patient management, especially with greater awareness that the majority of patients do not die from their BM. Being aware of significant heterogeneity in prognosis and therapeutic options for patients with BM is crucial for appropriate management, with greater attention to developing individual patient treatment plans based on predicted outcomes; in this context, recent prognostic models of survival have been extensively revised to incorporate molecular markers unique to different primary cancers.

Debate: adjuvant whole brain radiotherapy or not? More data is the wiser choice

Every year 170,000 patients are diagnosed with brain metastases (BMs) in the United States. Traditionally, adjuvant whole brain radiotherapy (AWBRT) has been offered following local therapy with neurosurgery (NSx) and/or stereotactic radiosurgery (SRS) to BMs. The aim is to increase intracranial control, thereby decreasing symptoms from intracranial progression and a neurological death. There is a rapidly evolving change in the radiation treatment of BMs happening around the world. AWBRT is now being passed over in favour of repeat scanning at regular intervals and more local therapies as more BMs appear radiologically, BMs that may never become symptomatic. This change has happened after the American Society for Radiation Oncology (ASTRO) in Item 5 of its “Choosing Wisely 2014” list recommended: “Don't routinely add adjuvant whole brain radiation therapy to SRS for limited brain metastases”. The guidelines are supposed to be based on the highest evidence to hand at the time. This article debates that the randomised controlled trials (RCTs) published prior to this recommendation consistently showed AWBRT significantly increases intracranial control, and avoids a neurological death, what it is meant to do. It also points out that, despite the enormity of the problem, only 774 patients in total had been randomised over more than three decades. These trials were heterogeneous in many respects. This data can, at best, be regarded as preliminary. In particular, there are no single histology AWBRT trials yet completed. A phase two trial investigating hippocampal avoiding AWBRT (HAWBRT) showed significantly less NCF decline compared to historical controls. We now need more randomised data to confirm the benefit of adjuvant HAWBRT. However, the ASTRO Guideline has particularly impacted accrual to trials investigating this, especially the international ANZMTG 01.07 WBRTMel trial. This is an RCT investigating AWBRT following local treatment in patients with one to three BMs from melanoma. WBRTMel has accrued 196 of a required 220 to date but accrual has slowed. HAWBRT may now never be tested in a randomised setting. Encouraging more data in AWBRT is the wiser choice.