BRAF Mutation Is Associated with Improved Local Control of Melanoma Brain Metastases Treated with Gamma Knife Radiosurgery.

OBJECTIVES: Evidence has implicated a possible role of tumor mutation status on local control (LC) with radiotherapy. BRAF is a proto-oncogene that is mutated in approximately 50% of patients with melanoma. We sought to analyze the influence of BRAF status on LC of melanoma brain metastases (MBM) following Gamma Knife radiosurgery (GK). METHODS: Among 125 patients treated with GK for MBM at our institution between 2006 and 2015, we identified 19 patients with 69 evaluable metastases whose BRAF mutation status was known and follow-up imaging was available. LC of individual metastases was compared based on BRAF mutation status using statistical techniques to control for measurements of multiple metastases within each patient. CNS progression was defined as either local failure or development of new lesions. RESULTS: Of the 69 metastases, BRAF was mutated in 30 and wild-type in 39. With a median follow-up of 30 months for all patients and a median follow-up of 5.5 months for treated lesions, 1-year LC was significantly better among metastases with mutated vs. wild-type BRAF (69 vs. 34%, RR = 0.3, 95% CI = 0.1-0.7, p = 0.01). BRAF mutation was found to be a significant predictor of LC after stereotactic radiosurgery (SRS) in both univariate [RR = 0.3 (95% CI 0.1-0.7, p = 0.01)] and multivariate [RR = 0.2 (95% CI 0.1-0.7, p = 0.01)] analyses. There was also a trend toward improved CNS progression free survival (PFS) at 1 year (26 vs. 0%, p = 0.06), favoring BRAF-mutated patients. CONCLUSION: In this retrospective study, MBM treated with GK had significantly improved LC for patients with BRAF mutation vs. wild-type. Our data suggest that BRAF mutation may sensitize tumors to radiosurgery, and that BRAF wild-type tumors may be more radioresistant.

Disseminated tumor cells in prostate cancer patients after radical prostatectomy and without evidence of disease predicts biochemical recurrence.

PURPOSE: Men with apparently localized prostate cancer often relapse years after radical prostatectomy. We sought to determine if epithelial-like cells identified from bone marrow in patients after radical prostatectomy, commonly called disseminated tumor cells (DTC), were associated with biochemical recurrence. EXPERIMENTAL DESIGN: We obtained bone marrow aspirates from 569 men prior to radical prostatectomy and from 34 healthy men with prostate-specific antigens <2.5 ng/mL to establish a comparison group. Additionally, an analytic cohort consisting of 98 patients with no evidence of disease (NED) after radical prostatectomy was established to evaluate the relationship between DTC and biochemical recurrence. Epithelial cells in the bone marrow were detected by magnetic bead enrichment with antibodies to CD45 and CD61 (negative selection) followed by antibodies to human epithelial antigen (positive selection) and confirmation with FITC-labeled anti-BerEP4 antibody. RESULTS: DTC were present in 72% (408 of 569) of patients prior to radical prostatectomy. There was no correlation with pathologic stage, Gleason grade, or preoperative prostate-specific antigens. Three of 34 controls (8.8%) had DTC present. In patients with NED after radical prostatectomy, DTC were present in 56 of 98 (57%). DTC were detected in 12 of 14 (86%) NED patients after radical prostatectomy who subsequently suffered biochemical recurrence. The presence of DTC in NED patients was an independent predictor of recurrence (hazard ratio 6.9; 95% confidence interval, 1.03-45.9). CONCLUSIONS: Approximately 70% of men undergoing radical prostatectomy had DTC detected in their bone marrow prior to surgery, suggesting that these cells escape early in the disease. Although preoperative DTC status does not correlate with pathologic risk factors, persistence of DTC after radical prostatectomy in NED patients was an independent predictor of recurrence.

Genomic alterations indicate tumor origin and varied metastatic potential of disseminated cells from prostate cancer patients.

Disseminated epithelial cells can be isolated from the bone marrow of a far greater fraction of prostate-cancer patients than the fraction of patients who progress to metastatic disease. To provide a better understanding of these cells, we have characterized their genomic alterations. We first present an array comparative genomic hybridization method capable of detecting genomic changes in the small number of disseminated cells (10-20) that can typically be obtained from bone marrow aspirates of prostate-cancer patients. We show multiple regions of copy-number change, including alterations common in prostate cancer, such as 8p loss, 8q gain, and gain encompassing the androgen-receptor gene on Xq, in the disseminated cell pools from 11 metastatic patients. We found fewer and less striking genomic alterations in the 48 pools of disseminated cells from patients with organ-confined disease. However, we identify changes shared by these samples with their corresponding primary tumors and prostate-cancer alterations reported in the literature, evidence that these cells, like those in advanced disease, are disseminated tumor cells (DTC). We also show that DTCs from patients with advanced and localized disease share several abnormalities, including losses containing cell-adhesion genes and alterations reported to associate with progressive disease. These shared alterations might confer the capability to disseminate or establish secondary disease. Overall, the spectrum of genomic deviations is evidence for metastatic capacity in advanced-disease DTCs and for variation in that capacity in DTCs from localized disease. Our analysis lays the foundation for elucidation of the relationship between DTC genomic alterations and progressive prostate cancer.