Stereotactic Cavity Irradiation or Whole-Brain Radiotherapy Following Brain Metastases Resection-Outcome, Prognostic Factors, and Recurrence Patterns.

Introduction: Following the resection of brain metastases (BM), whole-brain radiotherapy (WBRT) is a long-established standard of care. Its position was recently challenged by the less toxic single-session radiosurgery (SRS) or fractionated stereotactic radiotherapy (FSRT) of the resection cavity, reducing dose exposure of the healthy brain. Patients and Methods: We analyzed 101 patients treated with either SRS/FSRT (n = 50) or WBRT (n = 51) following BM resection over a 5-year period. Propensity score adjustment was done for age, total number of BM, timepoint of BM diagnosis, controlled primary and extracranial metastases. A Cox Proportional Hazards model with univariate and multivariate analysis was fitted for overall survival (OS), local control (LC) and distant brain control (DBC). Results: Median patient age was 61 (interquartile range, IQR: 56-67) years and the most common histology was non-small cell lung cancer, followed by breast cancer. 38% of the patients had additional unresected BM. Twenty-four patients received SRS, 26 patients received FSRT and 51 patients received WBRT. Median OS in the SRS/FSRT subgroup was not reached (IQR NA-16.7 months) vs. 12.6 months (IQR 21.3-4.4) in the WBRT subgroup (hazard ratio, HR 3.3, 95%-CI: [1.5; 7.2] p < 0.002). Twelve-months LC-probability was 94.9% (95%-CI: [88.3; 100.0]) in the SRS subgroup vs. 81.7% (95%-CI: [66.6; 100.0]) in the WBRT subgroup (HR 0.2, 95%-CI: [0.01; 0.9] p = 0.037). Twelve-months DBC-probabilities were 65.0% (95%-CI: [50.8; 83.0]) and 58.8% (95%-CI: [42.9; 80.7]), respectively (HR 1.4, 95%-CI: [0.7; 2.7] p = 0.401). In propensity score-adjusted multivariate analysis, incomplete resection negatively impacted OS (HR 3.9, 95%-CI: [2.0;7.4], p < 0.001) and LC (HR 5.4, 95%-CI: [1.3; 21.9], p = 0.018). Excellent clinical performance (HR 0.4, 95%-CI: [0.2; 0.9], p = 0.030) and better graded prognostic assessment (GPA) score (HR 0.4, 95%-CI: [0.2; 1.0], p = 0.040) were prognostic of superior OS. A higher number of BM was associated with a greater risk of developing new distant BM (HR 5.6, 95%-CI: [1.0; 30.4], p = 0.048). In subgroup analysis, larger cavity volume (HR 1.1, 95%-CI: [1.0; 1.3], p = 0.033) and incomplete resection (HR 12.0, 95%-CI: [1.2; 118.3], p = 0.033) were associated with inferior LC following SRS/FSRT. Conclusion: This is the first propensity score-adjusted direct comparison of SRS/FSRT and WBRT following the resection of BM. Patients receiving SRS/FSRT showed longer OS and LC compared to WBRT. Future analyses will address the optimal choice of safety margin, dose and fractionation for postoperative stereotactic RT of the resection cavity.

Single-Isocenter Volumetric Modulated Arc Therapy vs. CyberKnife M6 for the Stereotactic Radiosurgery of Multiple Brain Metastases.

Introduction: Stereotactic radiosurgery (SRS) is becoming more frequently used for patients with multiple brain metastases (BMs). Single-isocenter volumetric modulated arc therapy (SI-VMAT) is an emerging alternative to dedicated systems such as CyberKnife (CK). We present a dosimetric comparison between CyberKnife M6 and SI-VMAT, planned at RayStation V8B, for the simultaneous SRS of five or more BM. Patients and Methods: Twenty treatment plans of CK-based single-session SRS to ≥5 brain metastases were replanned using SI-VMAT for delivery at an Elekta VersaHD linear accelerator. Prescription dose was 20 or 18 Gy, conformally enclosing at least 98% of the total planning target volume (PTV), with PTV margin-width adapted to the respective SRS technique. Comparatively analyzed quality metrics included dose distribution to the healthy brain (HB), including different isodose volumes, conformity, and gradient indices. Estimated treatment time was also compared. Results: Median HB isodose volumes for 3, 5, 8, 10, and 12 Gy were consistently smaller for CK-SRS compared to SI-VMAT (p < 0.001). Dose falloff outside the target volume, as expressed by the gradient indices GI_high and GI_low, was consistently steeper for CK-SRS compared to SI-VMAT (p < 0.001). CK-SRS achieved a median GI_high of 3.1 [interquartile range (IQR), 2.9-1.3] vs. 5.0 (IQR 4.3-5.5) for SI-VMAT (p < 0.001). For GI_low, the results were 3.0 (IQR, 2.9-3.1) for CK-SRS vs. 5.6 (IQR, 4.3-5.5) for SI-VMAT (p < 0.001). The median conformity index (CI) was 1.2 (IQR, 1.1-1.2) for CK-SRS vs. 1.5 (IQR, 1.4-1.7) for SI-VMAT (p < 0.001). Estimated treatment time was shorter for SI-VMAT, yielding a median of 13.7 min (IQR, 13.5-14.0) compared to 130 min (IQR, 114.5-154.5) for CK-SRS (p < 0.001). Conclusion: SI-VMAT offers enhanced treatment efficiency in cases with multiple BM, as compared to CyberKnife, but requires compromise regarding conformity and integral dose to the healthy brain. Additionally, delivery at a conventional linear accelerator (linac) may require a larger PTV margin to account for delivery and setup errors. Further evaluations are warranted to determine whether the detected dosimetric differences are clinically relevant. SI-VMAT could be a reasonable alternative to a dedicated radiosurgery system for selected patients with multiple BM.

A matched-pair analysis comparing stereotactic radiosurgery with whole-brain radiotherapy for patients with multiple brain metastases.

INTRODUCTION: Stereotactic radiosurgery (SRS) is an emerging treatment for patients with multiple brain metastases (BM). The present work compares the SRS of multiple brain metastases with whole-brain radiotherapy (WBRT). METHODS: We performed a matched-pair analysis for 128 patients with multiple BM treated with either SRS or WBRT over a 5-year period. Patients were matched pairwise for seven potential prognostic factors. A mixed Cox Proportional Hazards model with univariate and multivariate analysis was fitted for overall survival (OS). Distant intracranial progression-free survival (icPFS) and local control were assessed using a Fine and Gray subdistribution hazard model and considering death as competing event. RESULTS: Patients undergoing SRS had a median of 4 BM (range 3-16). 1-year local control of individual BM following SRS was 91.7%. Median OS in the SRS subgroup was 15.7 months (IQR 9.7-36.4) versus 8.0 months (interquartile range, IQR 3.8-18.0) in the WBRT subgroup (HR 2.25, 95% CI [1.5; 3.5], p < 0.001). Median icPFS was 8.6 (IQR 3.4-18.0) versus 22.4 (IQR 5.6-28.6) months, respectively (HR for WBRT 0.41, 95% CI [0.24; 0.71], p = 0.001). Following SRS, synchronous BM diagnosis (HR 2.51, 95% CI [1.30; 4.70], p = 0.004), higher initial number of BM (HR 1.21, 95% CI [1.10; 1.40], p = 0.002) and lung cancer histology (HR 2.05, 95% CI [1.10; 3.80], p = 0.024) negatively impacted survival. Excellent clinical performance (KPI 90%) was a positive prognosticator (HR 0.38, 95% CI [0.20; 0.72], p = 0.003), as was extracerebral tumor control (HR 0.48, 95% CI [0.24; 0.97], p = 0.040). Higher initial (HR 1.19, 95% CI [1.00; 1.40], p < 0.013) and total number of BM (HR 1.23, 95% CI [1.10; 1.40], p < 0.001) were prognostic for shorter icPFS. CONCLUSION: This is the first matched-pair analysis to compare SRS alone versus WBRT alone for multiple BM. OS was prolonged in the SRS subgroup and generally favorable in the entire cohort. Our results suggest SRS as a feasible and effective treatment for patients with multiple BM.

The complement system in cancer: Ambivalence between tumour destruction and promotion.

Constituting a part of the innate immune system, the complement system consists of over 50 proteins either acting as part of a 3-branch activation cascade, a well-differentiated regulatory system in fluid phase or on each tissue, or as receptors translating the activation signal to multiple cellular effector functions. Complement serves as first line of defence against infections from bacteria, viruses and parasites by orchestrating the immune response through opsonisation, recruitment of immune cells to the site of infection and direct cell lysis. Complement is generally recognised as a protective mechanism against the formation of tumours in humans, but is often limited by various resistance mechanisms interfering with its cytotoxic action, now considered as a great barrier of successful antibody-based immunotherapy. However, recent studies also indicate a pro-tumourigenic potential of complement in certain cancers and under certain conditions. In this review, we present recent findings on the possible dual role of complement in destroying cancer, especially if resistance mechanisms are blocked, but also under certain inflammatory conditions-promoting tumour development.

Neutralization of membrane complement regulators improves complement-dependent effector functions of therapeutic anticancer antibodies targeting leukemic cells.

Complement-dependent cytotoxicity (CDC) is one of the effector mechanisms mediated by therapeutic anticancer monoclonal antibodies (mAbs). However, the efficacy of antibodies is limited by the resistance of malignant cells to complement attack, primarily due to the over-expression of one or more membrane complement regulatory proteins (mCRPs) CD46, CD55, and CD59. CD20-positive Burkitt lymphoma Raji cells and primary CLL cells are resistant to rituximab (RTX)-induced CDC whereas ofatumumab (OFA) proved to be more efficient in cell killing. Primary CLL cells but not CD52-positive acute lymphoblastic leukemia (ALL) REH cells were sensitive to alemtuzumab (ALM)-induced CDC. Upon combined inhibition on Raji and CLL cells by mCRPs-specific siRNAs or neutralizing antibodies, CDC induced by RTX and by OFA was augmented. Similarly, CDC of REH cells was enhanced after mCRPs were inhibited upon treatment with ALM. All mAbs induced C3 opsonization, which was significantly augmented upon blocking mCRPs. C3 opsonization led to enhanced cell-mediated cytotoxicity of leukemia cells exposed to PBLs or macrophages. Furthermore, opsonized CLL cells were efficiently phagocytized by macrophages. Our results provide conclusive evidence that inhibition of mCRPs expression sensitizes leukemic cells to complement attack thereby enhancing the therapeutic effect of mAbs targeting leukemic cells.