Five fraction image-guided radiosurgery for primary and recurrent meningiomas

PURPOSE

Benign tumors that arise from the meninges can be difficult to treat due to their potentially large size and proximity to critical structures such as cranial nerves and sinuses. Single fraction radiosurgery may increase the risk of symptomatic peritumoral edema. In this study, we report our results on the efficacy and safety of five fraction image-guided radiosurgery for benign meningiomas.

MATERIALS/METHODS

Clinical and radiographic data from 38 patients treated with five fraction radiosurgery were reviewed retrospectively. Mean tumor volume was 3.83 mm(3) (range, 1.08-20.79 mm(3)). Radiation was delivered using the CyberKnife, a frameless robotic image-guided radiosurgery system with a median total dose of 25 Gy (range, 25-35 Gy).

RESULTS

The median follow-up was 20 months. Acute toxicity was minimal with eight patients (21%) requiring a short course of steroids for headache at the end of treatment. Pre-treatment neurological symptoms were present in 24 patients (63.2%). Post treatment, neurological symptoms resolved completely in 14 patients (58.3%), and were persistent in eight patients (33.3%). There were no local failures, 24 tumors remained stable (64%) and 14 regressed (36%). Pre-treatment peritumoral edema was observed in five patients (13.2%). Post-treatment asymptomatic peritumoral edema developed in five additional patients (13.2%). On multivariate analysis, pre-treatment peritumoral edema and location adjacent to a large vein were significant risk factors for radiographic post-treatment edema (p = 0.001 and p = 0.026 respectively).

CONCLUSION

These results suggest that five fraction image-guided radiosurgery is well tolerated with a response rate for neurologic symptoms that is similar to other standard treatment options. Rates of peritumoral edema and new cranial nerve deficits following five fraction radiosurgery were low. Longer follow-up is required to validate the safety and long-term effectiveness of this treatment approach.

Rectal endoscopy findings following stereotactic body radiation therapy for clinically localized prostate cancer

Background

Treating prostate cancer with SBRT could potentially minimize radiation proctitis by reducing high-dose rectal irradiation. In addition, it offers the potential radiobiologic benefits of hypofractionation. This study reports the endoscopic changes and the associated clinical rectal toxicity in these patients.

Methods

We reviewed the records of patients treated from 2008–2011 for localized prostate cancer who had rectal endoscopy following SBRT. SBRT was delivered either as primary treatment in 5 fractions of 7–7.25 Gy, or as an initial boost in 3 fractions of 6.5 Gy followed by conventionally fractionated radiotherapy to 45–50.4 Gy. Endoscopic changes were graded using the Vienna Rectoscopy Score (VRS). Rectal toxicity was graded via CTCAEv.4. Rectal quality of life (QOL) was assessed via the bowel domain of the EPIC-26 questionnaire.

Results

Fifty-one patients with a median 23 months follow-up were analyzed. Thirty-five patients completed SBRT monotherapy and 16 patients received SBRT as a boost to conventionally fractionated IMRT. The median interval from SBRT to rectal endoscopy was 13 months. Endoscopy revealed VRS Grade 1–2 telangiectasias for 10 patients and VRS Grade 1–2 mucosal edema for 12 patients. No rectal ulcerations, strictures or necrosis were observed. Grade 1–2 late rectal bleeding occurred in 10 patients. There were no CTCAEv.4 Grade ≥3 toxicities. Mean EPIC bowel scores decreased from a baseline value of 96.9 to 82.3 at 1-month, but subsequently increased to 91.0 at 24 months.

Conclusions

In this cohort that is skewed towards patients with rectal complaints, the rate and severity of endoscopic changes following SBRT is low. Rectal toxicity and QOL were comparable to patients treated with other radiation modalities. Prospective trials examining the endoscopic outcomes following SBRT for prostate cancer are needed for confirmation of the findings of this study.

Trial registration

The Georgetown Institutional Review Board has approved this retrospective study (IRB 2009–510).

Stereotactic body radiation therapy (SBRT) for clinically localized prostate cancer: the Georgetown University experience

Background

Stereotactic body radiation therapy (SBRT) delivers fewer high-dose fractions of radiation which may be radiobiologically favorable to conventional low-dose fractions commonly used for prostate cancer radiotherapy. We report our early experience using SBRT for localized prostate cancer.

Methods

Patients treated with SBRT from June 2008 to May 2010 at Georgetown University Hospital for localized prostate carcinoma, with or without the use of androgen deprivation therapy (ADT), were included in this retrospective review of data that was prospectively collected in an institutional database. Treatment was delivered using the CyberKnife® with doses of 35 Gy or 36.25 Gy in 5 fractions. Biochemical control was assessed using the Phoenix definition. Toxicities were recorded and scored using the CTCAE v.3. Quality of life was assessed before and after treatment using the Short Form-12 Health Survey (SF-12), the American Urological Association Symptom Score (AUA) and Sexual Health Inventory for Men (SHIM) questionnaires. Late urinary symptom flare was defined as an AUA score ≥ 15 with an increase of ≥ 5 points above baseline six months after the completion of SBRT.

Results

One hundred patients (37 low-, 55 intermediate- and 8 high-risk according to the D’Amico classification) at a median age of 69 years (range, 48–90 years) received SBRT, with 11 patients receiving ADT. The median pre-treatment prostate-specific antigen (PSA) was 6.2 ng/ml (range, 1.9-31.6 ng/ml) and the median follow-up was 2.3 years (range, 1.4-3.5 years). At 2 years, median PSA decreased to 0.49 ng/ml (range, 0.1-1.9 ng/ml). Benign PSA bounce occurred in 31% of patients. There was one biochemical failure in a high-risk patient, yielding a two-year actuarial biochemical relapse free survival of 99%. The 2-year actuarial incidence rates of GI and GU toxicity ≥ grade 2 were 1% and 31%, respectively. A median baseline AUA symptom score of 8 significantly increased to 11 at 1 month (p = 0.001), however returned to baseline at 3 months (p = 0.60). Twenty one percent of patients experienced a late transient urinary symptom flare in the first two years following treatment. Of patients who were sexually potent prior to treatment, 79% maintained potency at 2 years post-treatment.

Conclusions

SBRT for clinically localized prostate cancer was well tolerated, with an early biochemical response similar to other radiation therapy treatments. Benign PSA bounces were common. Late GI and GU toxicity rates were comparable to conventionally fractionated radiation therapy and brachytherapy. Late urinary symptom flares were observed but the majority resolved with conservative management. A high percentage of men who were potent prior to treatment remained potent two years following treatment.

Stereotactic body radiation therapy with concurrent full-dose gemcitabine for locally advanced pancreatic cancer: a pilot trial demonstrating safety

Background

Concurrent chemoradiation is a standard option for locally advanced pancreatic cancer (LAPC). Concurrent conventional radiation with full-dose gemcitabine has significant toxicity. Stereotactic body radiation therapy (SBRT) may provide the opportunity to administer radiation in a shorter time frame with similar efficacy and reduced toxicity. This Pilot study assessed the safety of concurrent full-dose gemcitabine with SBRT for LAPC.

Methods

Patients received gemcitabine, 1000 mg/m² for 6 cycles. During week 4 of cycle 1, patients received SBRT (25 Gy delivered in five consecutive daily fractions of 5 Gy prescribed to the 75-83% isodose line). Acute and late toxicities were assessed using NIH CTCAE v3. Tumor response was assessed by RECIST. Patients underwent an esophagogastroduodenoscopy at baseline, 2, and 6 months to assess the duodenal mucosa. Quality of life (QoL) data was collected before and after treatment using the QLQ-C30 and QLQ-PAN26 questionnaires.

Results

Between September 2009 and February 2011, 11 patients enrolled with one withdrawal during radiation therapy. Patients had grade 1 to 2 gastrointestinal toxicity from the start of SBRT to 2 weeks after treatment. There were no grade 3 or greater radiation-related toxicities or delays for cycle 2 of gemcitabine. On endoscopy, there were no grade 2 or higher mucosal toxicities. Two patients had a partial response. The median progression free and overall survival were 6.8 and 12.2 months, respectively. Global QoL did not change between baseline and immediately after radiation treatment.

Conclusions

SBRT with concurrent full dose gemcitabine is safe when administered to patients with LAPC. There is no delay in administration of radiation or chemotherapy, and radiation is completed with minimal toxicity.

Stereotactic body radiation therapy (SBRT) following procedures for benign prostatic hyperplasia (BPH): A report on early toxicity

165

Background: When treating patients with prostate cancer, hypofractionation with SBRT takes advantage of radiobiologically favorable factors as compared to conventional fractionation. However, this may increase the risk of urinary toxicity, especially in patients with prior procedures for BPH. Herein, we report early urinary toxicity following SBRT in patients with a history of procedures for BPH. Methods: Thirty three patients treated with SBRT for localized prostate cancer from February 2009 to October 2011 at Georgetown University Hospital with history of a prior procedure for BPH were included in this retrospective analysis. Treatment was delivered using the CyberKnife with doses of 35 Gy-36.25 Gy in 5 fractions. Toxicities were scored using the CTCAE v.3. Cystoscopy findings were retrospectively reviewed. Patient-reported urinary symptoms were assessed using the American Urological Association Symptom Score (AUA). Results: The median age was 70 years (range, 64 - 84). The median follow-up time was 18.7 months (range 9.2 – 38.9). Grade 2 or 3 urinary toxicity occurred in 9 patients and there were no grade 4 or 5 toxicities. Hematuria occurred in 12 patients. The median time to onset of hematuria from SBRT was 6 months (range 1 – 30). Grade 1 hematuria occurred in 7 patients, grade 2 in 4 patients and 1 patient experienced grade 3. Cystoscopy was performed in 9 of these patients at a median time of 9 months (range 3-27). Eight had hyperemia or evidence of bleeding from the prostatic urethra and 5 of these patients also had evidence of bleeding from the bladder neck/wall. All patients except one, who died from other causes, are still being followed and hematuria has resolved in 9 of the 12 patients. The median baseline AUA symptom score of 7 increased to 11 at 1 month, however decreased to a median score of 6 at 3 months. The median AUA symptom score increased to 9 at 1 year. Conclusions: A history of prior transurethral resection of prostate may predispose patients to increased urinary toxicity and hematuria following prostate SBRT. Stricter urethra/bladder neck dosimetric criteria or alternative fractionation regimens may be required to decrease urinary toxicity in these patients.

Hypofractionated stereotactic body radiation therapy as monotherapy for intermediate-risk prostate cancer

BACKGROUND

Hypofractionated stereotactic body radiation therapy (SBRT) has been advanced as monotherapy for low-risk prostate cancer. We examined the dose distributions and early clinical outcomes using this modality for the treatment of intermediate-risk prostate cancer.

METHODS

Forty-one sequential hormone-naïve intermediate-risk prostate cancer patients received 35-36.25 Gy of CyberKnife-delivered SBRT in 5 fractions. Radiation dose distributions were analyzed for coverage of potential microscopic ECE by measuring the distance from the prostatic capsule to the 33 Gy isodose line. PSA levels, toxicities, and quality of life (QOL) measures were assessed at baseline and follow-up.

RESULTS

All patients completed treatment with a mean coverage by the 33 Gy isodose line extending >5 mm beyond the prostatic capsule in all directions except posteriorly. Clinical responses were documented by a mean PSA decrease from 7.67 ng/mL pretreatment to 0.64 ng/mL at the median follow-up of 21 months. Forty patients remain free from biochemical progression. No Grade 3 or 4 toxicities were observed. Mean EPIC urinary irritation/obstruction and bowel QOL scores exhibited a transient decline post-treatment with a subsequent return to baseline. No significant change in sexual QOL was observed.

CONCLUSIONS

In this intermediate-risk patient population, an adequate radiation dose was delivered to areas of expected microscopic ECE in the majority of patients. Although prospective studies are needed to confirm long-term tumor control and toxicity, the short-term PSA response, biochemical relapse-free survival rate, and QOL in this interim analysis are comparable to results reported for prostate brachytherapy or external beam radiotherapy.

TRIAL REGISTRATION

The Georgetown Institutional Review Board has approved this retrospective study (IRB 2009-510).

Low incidence of fatigue after hypofractionated stereotactic body radiation therapy for localized prostate cancer

Background: Fatigue is a common side effect of conventional prostate cancer radiation therapy. The increased delivery precision necessitated by the high dose per fraction of stereotactic body radiation therapy (SBRT) offers the potential of reduce target volumes and hence the exposure of normal tissues to high radiation doses. Herein, we examine the level of fatigue associated with SBRT treatment. Methods: Forty patients with localized prostate cancer treated with hypofractionated SBRT, and a minimum of 12 months follow-up were included in this analysis. Self-reported fatigue and other quality of life measures were assessed at baseline and at 1, 3, 6, 9, and 12 months post-SBRT. Results: Mean levels of fatigue were elevated at 1 month post-SBRT compared to baseline values (P = 0.02). Fatigue at the 3-month follow-up and later were higher but not statistically significantly different compared to baseline. African-American patients reported higher fatigue post-SBRT than Caucasian patients. Fatigue was correlated with hormonal symptoms as measured by the Expanded Prostate Cancer Index Composite (EPIC) quality of life questionnaire, but not with urinary, bowel, or sexual symptoms. Age, co-morbidities, smoking, prostate specific antigen (PSA) levels, testosterone levels, tumor stage, and treatment variables were not associated with fatigue. Conclusion: This is the first study to investigate fatigue as a side effect of SBRT. In contrast to standard radiation therapy, results suggest SBRT-related fatigue is short-term rather than a long-term side effect of SBRT. These results also suggest post-SBRT fatigue to be a more frequent complication in African-Americans than Caucasians.

CyberKnife with Tumor Tracking: An Effective Treatment for High-Risk Surgical Patients with Single Peripheral Lung Metastases

Standard treatment for operable patients with single peripheral lung metastases is metastasectomy. We report mature CyberKnife outcomes for high-risk surgical patients with biopsy proven single peripheral lung metastases. Twenty-four patients (median age 73 years) with a mean maximum tumor diameter of 2.5 cm (range, 0.8–4.5 cm) were treated over a 6-year period extending from September 2004 to September 2010 and followed for a minimum of 1 year or until death. A mean dose of 52 Gy (range, 45–60 Gy) was delivered to the prescription isodose line in three fractions over a 3–11 day period (mean, 7 days). At a median follow-up of 20 months, the 2-year Kaplan–Meier local control and overall survival rates were 87 and 50%, respectively. CyberKnife with fiducial tracking is an effective treatment for high-risk surgical patients with single small peripheral lung metastases. Trials comparing CyberKnife with metastasectomy for operable patients are necessary to confirm equivalence.

Fiducial-free CyberKnife stereotactic body radiation therapy (SBRT) for single vertebral body metastases: acceptable local control and normal tissue tolerance with 5 fraction approach

This retrospective analysis examines the local control and toxicity of five-fraction fiducial-free CyberKnife stereotactic body radiation therapy (SBRT) for single vertebral body (VB) metastases. All patients had favorable performance status (ECOG 0-1), oligometastatic disease, and no prior spine irradiation. A prescribed dose of 30-35 Gy was delivered in five fractions to the planning target volume (PTV) using the CyberKnife with X-sight spine tracking. Suggested maximum spinal cord and esophagus point doses were 30 and 40 Gy, respectively. A median 30 Gy (IQR, 30-35 Gy) dose was delivered to a median prescription isodose line of 70% (IQR, 65-77%) to 20 patients. At 34 months median follow-up (IQR, 25-40 months) for surviving patients, the 1- and 2-year Kaplan-Meier local control estimates were 80 and 73%, respectively. Two of the five local failures were infield in patients who had received irradiation to the gross tumor volume and three were paravertebral failures just outside the PTV in patients with prior corpectomy. No local failures occurred in patients who completed VB radiation alone. The 1- and 2-year Kaplan-Meier overall survival estimates were 80 and 57%, respectively. Most deaths were attributed to metastatic disease; one death was attributed to local recurrence. The mean maximum point doses were 26.4 Gy (SD, 5.1 Gy) to the spinal cord and 29.1 Gy (SD, 8.9 Gy) to the esophagus. Patients receiving maximum esophagus point doses greater than 35 Gy experienced acute dysphagia (Grade I/II). No spinal cord toxicity was documented. Five-fraction fiducial-free CyberKnife SBRT is an acceptable treatment option for newly diagnosed VB metastases with promising local control rates and minimal toxicity despite the close proximity of such tumors to the spinal cord and esophagus. A prospective study aimed at further enhancing local control by targeting the intact VB and escalating the total dose is planned.

Abstract 5028: MicroRNA-212 targets multiple signaling pathways in prostate cancer

Prostate cancer (PCa) is the most common type of cancer in men in the United States. While metastasis is the most common cause of death among PCa patients, no specific markers have been assigned to the severity of the disease. Identification of molecular factors could improve diagnosis and therapeutic intervention of PCa. MicroRNAs represent a promising new class of circulating biomarkers owing to their inherent stability and resilience. Studies in our lab have demonstrated that miR-212 is a differentially modulated circulatory microRNA in prostate cancer patients. Identification and validation of miRNA targets provides functional insights in mechanisms of prostate carcinogenesis and strategies for therapy. The present study was aimed to investigate and validate the targets for miR-212 to elucidate its role in prostate cancer and identify potential biomarkers and/or therapeutic targets for prostate cancer. Common mRNA targets of miR-212 were extracted from four web-based databases: TargetScan, miRanda, RNAhybrid, and PicTar. Some of the important common targets for miR-212 included DEDD, E2F5, GRM3, G2L1, SPRED1, SIRT1, SOS1, RASA1, PEA15, MYC, MAPK3, MAPK1 and HMGA2. Out of these SIRT1, SOS1, SPRED1, RASA1 were picked for further validation based on their documented role in carcinogenesis and tumor progression. Transfection studies with miR-212 mimics were performed in PC3 and LnCap prostate cancer cell lines. Western blotting was used to see the initial expression of various targets. 3′UTR-Luciferase reporter assay was performed for validating the target inhibition by miR-212. In addition, Cell proliferation assay and wound-healing assay were performed to evaluate the effects of miR-212 on PCa cell proliferation and migration. In summary the present study identifies and validates miR-212 targets and examines the functional significance of miR-212 in prostate cancer (PCa) cells lines. *Contributed equally.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5028. doi:1538-7445.AM2012-5028

Abstract 206: A single nucleotide polymorphism (SNP) rs35301225 (A/C/T) in pre-miR-34a alters the cell cycle regulation

Prostate cancer (PCa) is the most common type of cancer in men in the United States and is expected to result in ∼218,000 new cases and about 32,000 deaths in 2010. Recently, microRNA miR-34a has been associated with many cancers including prostate cancer. It has been shown that tumor suppressor p53 transcriptionally regulates the expression of microRNA- miR-34a, which confers translational inhibition and mRNA degradation of genes involved in cell cycle control and apoptosis. Several GWAS studies have reported that Single nucleotide polymorphisms (SNPs) in microRNA coding genes (both in seed and mature sequence) or their target binding sites may alter the strength of miRNA binding and deregulate target gene expression. To our interest we aimed to explore the effect of germ line polymorphism rs35301225 (A/C/T) residing in miR-34a (rs35301225) on the cell cycle progression and apoptosis. Prostate (PC3 and LnCap) and breast cancer (MDA-MB 231) cell lines were transfected with pre miRNA mimics containing A/C/T alleles (rs35301225) of miR-34a and the expression of CYCLIN D1, CDK4, CDK6 and proteins associated with cellular signaling cascades, involved in cell cycle regulation were determined by Western blotting. Luciferase assay was performed for the target evaluation. The cell proliferation and apoptosis were measured by WST-1 assay and flow cytometry respectively. The expressions of apoptosis-related proteins were detected by Western blotting in the transfected cells. Western blot analysis showed that CYCLIN D1, CDK4, CDK6 and other downstream molecules were significantly down-regulated in the presence of C allele, whereas no such reduction of expression was observed in the presence of A or T allele. Cell proliferation assay showed that different alleles of miR-34a also exert profound effect on proliferation pattern of cells. Flow cytometry analysis also showed that cells with different alleles of miR-34a may exert significant effect on cell cycle progression and apoptosis. To explore if this phenomenon was confined to prostate cancer cell lines or different alleles of mir-34a may alter cell function in general, experiments were repeated with a breast cancer cell line, MDA-MB-231. Interestingly the results obtained in breast cancer cell lines were similar to that obtained in prostate cancer cell lines. The results suggest that genetic variants residing in the mature miRNA may exert a substantial effect on their expression and function, which needs to be explored along with the biological effect of miRNAs.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 206. doi:1538-7445.AM2012-206

CyberKnife with Tumor Tracking: An Effective Treatment for High-Risk Surgical Patients with Stage I Non-Small Cell Lung Cancer

Published data suggests that wedge resection for stage I non-small cell lung cancer (NSCLC) is associated with improved overall survival compared to stereotactic body radiation therapy. We report CyberKnife outcomes for high-risk surgical patients with biopsy-proven stage I NSCLC. PET/CT imaging was completed for staging. Three-to-five gold fiducial markers were implanted in or near tumors to serve as targeting references. Gross tumor volumes (GTVs) were contoured using lung windows; the margins were expanded by 5 mm to establish the planning treatment volume (PTV). Treatment plans were designed using a mean of 156 pencil beams. Doses delivered to the PTV ranged from 42 to 60 Gy in three fractions. The 30 Gy isodose contour extended at least 1 cm from the GTV to eradicate microscopic disease. Treatments were delivered using the CyberKnife system with tumor tracking. Examination and PET/CT imaging occurred at 3 month follow-up intervals. Forty patients (median age 76) with a median maximum tumor diameter of 2.6 cm (range, 1.4-5.0 cm) and a mean post-bronchodilator percent predicted forced expiratory volume in 1 s (FEV1) of 57% (range, 21-111%) were treated. A median dose of 48 Gy was delivered to the PTV over 3-13 days (median, 7 days). The 30 Gy isodose contour extended a mean 1.9 cm from the GTV. At a median 44 months (range, 12-72 months) follow-up, the 3 year Kaplan-Meier locoregional control and overall survival estimates compare favorably with contemporary wedge resection outcomes at 91 and 75%, respectively. CyberKnife is an effective treatment approach for stage I NSCLC that is similar to wedge resection, eradicating tumors with 1-2 cm margins in order to preserve lung function. Prospective randomized trials comparing CyberKnife with wedge resection are necessary to confirm equivalence.

Expression of Voltage-Gated Sodium Channel Nav1.8 in Human Prostate Cancer is Associated with High Histological Grade

Voltage-gated sodium (Na_v) channels are required for impulse conductance in excitable tissues. Na_vs have been linked to human cancers, including prostate. The expression and distribution of Na_v isoforms (Na_v1.1-Na_v1.9) in human prostate cancer are not well established. Here, we evaluated the expression of these isoforms and investigated the expression of Na_v1.8 in human prostate cancer tissues. Na_v1.8 was highly expressed in all examined cells. Expression of Na_v1.1, Na_v1.2, and Na_v1.9 were high in DU-145, PC-3 and PC-3M cells compared to LNCaP (hormone-dependent), C4-2, C4-2B, and CWR22Rv-1 cells. Na_v1.5 and Na_v1.6 were expressed in all cells examined. Na_v1.7 expression was absent in PC-3M and CWR22Rv-1, but expressed in the other cells examined. Immunohistochemistry revealed intensive Na_v1.8 staining correlated with more advanced pathologic stage of disease. Increased intensity of nuclear Na_v1.8 correlated with increased Gleason grade. Our results revealed that Na_v1.8 is universally expressed in human prostate cancer cells. Na_v1.8 expression statistically correlated with pathologic stage (P=0.04) and Gleason score (P=0.01) of human prostate tissue specimens. The aberrant nuclear localization of Na_v1.8 with advanced prostate cancer tissues warrant further investigation into use of Na_v1.8 as a potential biomarker to differentiate between early and advanced disease.

Six-Dimensional Correction of Intra-Fractional Prostate Motion with CyberKnife Stereotactic Body Radiation Therapy

Large fraction radiation therapy offers a shorter course of treatment and radiobiological advantages for prostate cancer treatment. The CyberKnife is an attractive technology for delivering large fraction doses based on the ability to deliver highly conformal radiation therapy to moving targets. In addition to intra-fractional translational motion (left-right, superior-inferior, and anterior-posterior), prostate rotation (pitch, roll, and yaw) can increase geographical miss risk. We describe our experience with six-dimensional (6D) intra-fraction prostate motion correction using CyberKnife stereotactic body radiation therapy (SBRT). Eighty-eight patients were treated by SBRT alone or with supplemental external radiation therapy. Trans-perineal placement of four gold fiducials within the prostate accommodated X-ray guided prostate localization and beam adjustment. Fiducial separation and non-overlapping positioning permitted the orthogonal imaging required for 6D tracking. Fiducial placement accuracy was assessed using the CyberKnife fiducial extraction algorithm. Acute toxicities were assessed using Common Toxicity Criteria v3. There were no Grade 3, or higher, complications and acute morbidity was minimal. Ninety-eight percent of patients completed treatment employing 6D prostate motion tracking with intra-fractional beam correction. Suboptimal fiducial placement limited treatment to 3D tracking in two patients. Our experience may guide others in performing 6D correction of prostate motion with CyberKnife SBRT.

Effects of a fluorescent Myosin light chain phosphatase inhibitor on prostate cancer cells

Myosin light chain phosphatase (MLCP) is an enzyme important to regulation of cell cycle and motility that is shown to be upregulated in aggressive prostate cancer cells and tissue. We developed a fluorescent small molecule inhibitor of MLCP using structure based design in recombinant protein phosphatase 1C. Several best fit compounds were synthesized and evaluated by their inhibition of MLCP/³²P-MLC dephosphorylation, which resulted in the identification of novel MLCP inhibitors. Androgen dependent (AD) and castration resistant prostate cancer cell (CRPC) lines were treated with the lead inhibitor resulting in decreased growth rate, reduced DNA synthesis, and G2/M cell cycle arrest. Moreover, CRPC cell lines showed an increased sensitivity to drug treatment having GI₅₀ values four times lower than the AD prostate cancer cell line. This was reinforced by reduced BrdU DNA incorporation into CRPC cells compared to AD cells. β-actin disruption was also seen at much lower drug concentrations in CR cells which caused a dose dependent reduction in cellular chemotaxis of PC-3 cells. Since there are currently few clinical therapeutics targeting CR prostate cancer, MLCP represents a new target for preclinical and clinical development of new potential therapeutics which inhibit this disease phenotype.

Asymmetric synthesis and evaluation of a hydroxyphenylamide voltage-gated sodium channel blocker in human prostate cancer xenografts

Voltage-gated sodium channels are known to be expressed in neurons and other excitable cells. Recently, voltage-gated sodium channels have been found to be expressed in human prostate cancer cells. α-Hydroxy-α-phenylamides are a new class of small molecules that have demonstrated potent inhibition of voltage-gated sodium channels. The hydroxyamide motif, an isostere of a hydantoin ring, provides an active scaffold from which several potent racemic sodium channel blockers have been derived. With little known about chiral preferences, the development of chiral syntheses to obtain each pure enantiomer for evaluation as sodium channel blockers is important. Using Seebach and Frater's chiral template, cyclocondensation of (R)-3-chloromandelic acid with pivaldehyde furnished both the cis- and trans-2,5-disubsituted dioxolanones. Using this chiral template, we synthesized both enantiomers of 2-(3-chlorophenyl)-2-hydroxynonanamide, and evaluated their ability to functionally inhibit hNa(v) isoforms, human prostate cancer cells and xenograft. Enantiomers of lead demonstrated significant ability to reduce prostate cancer in vivo.

Low incidence of new biochemical and clinical hypogonadism following hypofractionated stereotactic body radiation therapy (SBRT) monotherapy for low- to intermediate-risk prostate cancer

Background

The CyberKnife is an appealing delivery system for hypofractionated stereotactic body radiation therapy (SBRT) because of its ability to deliver highly conformal radiation therapy to moving targets. This conformity is achieved via 100s of non-coplanar radiation beams, which could potentially increase transitory testicular irradiation and result in post-therapy hypogonadism. We report on our early experience with CyberKnife SBRT for low- to intermediate-risk prostate cancer patients and assess the rate of inducing biochemical and clinical hypogonadism.

Methods

Twenty-six patients were treated with hypofractionated SBRT to a dose of 36.25 Gy in 5 fractions. All patients had histologically confirmed low- to intermediate-risk prostate adenocarcinoma (clinical stage ≤ T2b, Gleason score ≤ 7, PSA ≤ 20 ng/ml). PSA and total testosterone levels were obtained pre-treatment, 1 month post-treatment and every 3 months thereafter, for 1 year. Biochemical hypogonadism was defined as a total serum testosterone level below 8 nmol/L. Urinary and gastrointestinal toxicity was assessed using Common Toxicity Criteria v3; quality of life was assessed using the American Urological Association Symptom Score, Sexual Health Inventory for Men and Expanded Prostate Cancer Index Composite questionnaires.

Results

All 26 patients completed the treatment with a median 15 months (range, 13-19 months) follow-up. Median pre-treatment PSA was 5.75 ng/ml (range, 2.3-10.3 ng/ml), and a decrease to a median of 0.7 ng/ml (range, 0.2-1.8 ng/ml) was observed by one year post-treatment. The median pre-treatment total serum testosterone level was 13.81 nmol/L (range, 5.55 - 39.87 nmol/L). Post-treatment testosterone levels slowly decreased with the median value at one year follow-up of 10.53 nmol/L, significantly lower than the pre-treatment value (p < 0.013). The median absolute fall was 3.28 nmol/L and the median percent fall was 23.75%. There was no increase in biochemical hypogonadism at one year post-treatment. Average EPIC sexual and hormonal scores were not significantly changed by one year post-treatment.

Conclusions

Hypofractionated SBRT offers the radiobiological benefit of a large fraction size and is well-tolerated by men with low- to intermediate-risk prostate cancer. Early results are encouraging with an excellent biochemical response. The rate of new biochemical and clinical hypogonadism was low one year after treatment.