Determining the Impact of Spatial Heterogeneity on Genomic Prognostic Biomarkers for Localized Prostate Cancer.

Localized prostate tumors show remarkably diverse clinical courses, with some being cured by local therapy alone, while others rapidly relapse and have a lethal course despite precision surgery or radiotherapy. Many genomic biomarkers have been developed to predict this clinical behavior, but these are confounded by the extreme spatial heterogeneity of prostate tumors: most are multifocal and harbor multiple subclonal populations. To quantify the influence of spatial heterogeneity on genomic prognostic biomarkers, we developed a case-control high-risk cohort (n = 42) using a prospective registry, risk matched by clinicopathologic prognostic indices. Half of the cohort had early biochemical recurrence (BCR; ie, ≤18 mo), while half remained without evidence of disease for at least 48 mo after radical prostatectomy. We then genomically profiled multiple tumor foci per patient, analyzing 119 total specimens. These data allowed us to validate three published genomic prognostic biomarkers and quantify their sensitivity to tumor spatial heterogeneity. Remarkably, all three biomarkers robustly predicted early BCR, and all three were robust to spatiogenomic variability. These data suggest that DNA-based genomic biomarkers can overcome intratumoral heterogeneity: single biopsies may be sufficient to estimate the risk of early BCR after radical treatment in patients with high-risk disease. PATIENT SUMMARY: We investigated whether heterogeneity between tumor regions within the prostate affects the accuracy of DNA-based biomarkers predicting early relapse after prostatectomy. We observed persistent accuracy in predicting disease relapse, suggesting that spatial heterogeneity may not hinder biomarker performance.

Radiotherapy as a Single Modality in Primary Seminoma of the Prostate.

Extragonadal germ cell tumors (EGCTs) are uncommon, and those involving the prostate are rare. We report on a primary seminoma of the prostate in a 56-year-old male presenting with scrotal pain, urinary frequency and urgency, and erectile dysfunction. Digital rectal examination revealed a hard, markedly enlarged prostate projecting posteriorly into the rectum. All 12 cores from ultrasound-guided prostate biopsy revealed malignant cells that stained positive for OCT4, PLAP, and CD117. Imaging revealed a 10.2 cm x 7.8 cm x 8.4 cm prostate mass with irregular nodular margins extending superiorly to the base of the bladder and posteriorly abutting the anterior rectal wall. There was no evidence of distant metastatic disease on both nuclear medicine and CT scans of the chest, abdomen, and pelvis. An 11 mm right internal iliac lymph node and several tiny sub-centimeter external iliac nodes were noted bilaterally. The patient was treated with radiotherapy to the prostate and pelvic lymph nodes. The pelvic lymph nodes were treated with 20 Gy in eight fractions, followed by a boost to the prostate for a further 20 Gy in eight fractions. There was a significant response during treatment that allowed an adaptive boost for a further 10 Gy in four fractions to bring the total dose to the prostate to 50 Gy in 20 fractions. Treatment was well tolerated. Adjuvant chemotherapy was not recommended. He remains disease-free 24 months post-treatment. This case report indicates that like most seminomas, extragonadal seminomas are exquisitely sensitive to radiotherapy and may be considered for the primary treatment of non-metastatic disease. To our knowledge, this is the first reported case of the sole use of radiotherapy to treat a primary seminoma of the prostate.

Association of Innovations in Radiotherapy and Systemic Treatments With Clinical Outcomes in Patients With Melanoma Brain Metastasis From 2007 to 2016.

Importance: Treatments for melanoma brain metastasis changed between 2007 and 2016 with the advent of new radiotherapy techniques, targeted therapeutic agents, and immunotherapy. Changes in clinical outcomes over time have not been systematically investigated in large population-based studies. Objective: To investigate the association of innovations in radiotherapy techniques and systemic therapies with clinical outcomes among patients with melanoma brain metastasis. Design, Setting and Participants: This population-based cohort study included all patients who received radiotherapy and/or surgery for the treatment of melanoma brain metastasis in Ontario, Canada, between January 1, 2007, and June 30, 2016. Brain treatment patterns and clinical outcomes were described by period (2007-2009, 2010-2012, and 2013-2016). Provincial administrative records were used to obtain data on surgery, radiotherapy, and drugs. Follow-up data were censored on August 31, 2016. A Kaplan-Meier analysis and multivariable Cox regression analyses were performed. Data were analyzed between November 8, 2017 and May 13, 2020. Main Outcomes and Measures: Overall survival, whole-brain radiotherapy-free survival, and time to subsequent brain treatment. Results: A total of 1096 patients (mean [SD] age, 61.7 [14.0] years; 751 men [68.5%]) with melanoma brain metastasis received treatment in Ontario between January 1, 2007, and June 30, 2016. Of those, 326 patients received treatment from 2007 to 2009 (period 1), 310 patients received treatment from 2010 to 2012 (period 2), and 460 patients received treatment from 2013 to 2016 (period 3). Patient age, other sociodemographic characteristics, and disease factors were similar between periods. Whole-brain radiotherapy was the first local brain-directed treatment used in 246 patients (75.5%; 95% CI, 70.8%-80.1%) in period 1, decreasing to 239 patients (52.0%; 95% CI, 47.4%-56.5%) in period 3. The use of partial-brain radiotherapy techniques as the first treatment increased from 11 patients (3.4%; 95% CI, 1.4%-5.3%) in period 1 to 98 patients (21.3%; 95% CI, 17.6%-25.0%) in period 3. After the first treatment for melanoma brain metastasis, the use of BRAF and MEK inhibitors and immunotherapy increased from less than 6 patients (<1.8%; 95% CI, <0.4% to <3.3%) in period 1 to 188 patients (40.9%; 95% CI, 36.4%-45.4%) in period 3. Overall survival was greater in period 3 (1-year survival, 21.8% [95% CI, 17.9%-25.9%] and 2-year survival, 13.8% [95% CI, 10.4%-17.8%]; Wilcoxon P = .001) compared with period 1 (1-year survival, 12.3% [95% CI, 9.0%-16.1%] and 2-year survival, 6.4% [95% CI, 4.1%-9.5%]), with an adjusted hazard ratio (aHR) of 0.65 (95% CI, 0.56-0.77). The findings were unchanged after accounting for the variation in imaging practice between periods. Between period 1 and period 3, the use of whole-brain radiotherapy decreased (aHR, 0.32; 95% CI, 0.22-0.46), and the use of multiple brain-directed treatments increased (aHR, 2.16; 95% CI, 1.48-3.14). Conclusions and Relevance: These findings suggest that innovations in systemic therapy and radiotherapy are associated with improvements in clinical outcomes among patients with melanoma brain metastasis, even in population-wide routine practice. Overall survival improved over time, and the use of whole-brain radiotherapy decreased. However, many patients continued to receive whole-brain radiotherapy in the last period (2013-2016) examined.

Electromagnetic (EM) catheter path tracking in ultrasound-guided brachytherapy of the breast.

PURPOSE: To evaluate a novel navigation system for breast brachytherapy, based on ultrasound (US)-guided catheter needle implantations followed by electromagnetic (EM) tracking of catheter paths. METHODS: Breast phantoms were produced, containing US-visible tumors. Ultrasound was used to localize the tumor pose and volume within the phantom, followed by planning an optimal catheter pattern through the tumor using navigation software. An electromagnetic (EM)-tracked catheter needle was used to insert the catheters in the desired pattern. The inserted catheters were visualized on a post-implant CT, serving as ground truth. Electromagnetic (EM) tracking and reconstruction of the inserted catheter paths were performed by pulling a flexible EM guidewire through each catheter, performed in two clinical brachytherapy suites. The accuracy of EM catheter tracking was evaluated by calculating the Hausdorff distance between the EM-tracked and CT-based catheter paths. The accuracy and clinical feasibility of EM catheter tracking were also evaluated in three breast cancer patients, performed in a separate experiment room. RESULTS: A total of 71 catheter needles were implanted into 12 phantoms using US guidance and EM navigation, in an average ± SD time of 8.1 ± 2.9 min. The accuracy of EM catheter tracking was dependent on the brachytherapy suite: 2.0 ± 1.2 mm in suite 1 and 0.6 ± 0.2 mm in suite 2. EM catheter tracking was successfully performed in three breast brachytherapy patients. Catheter tracking typically took less than 5 min and had an average accuracy of 1.7 ± 0.3 mm. CONCLUSION: Our preliminary results show a potential role for US guidance and EM needle navigation for implantation of catheters for breast brachytherapy. EM catheter tracking can accurately assess the implant geometry in breast brachytherapy patients. This methodology has the potential to evaluate catheter positions directly after the implantation and during the several fractions of the treatment.

Systemic therapy of brain metastases.

Brain metastases are a common complication of cancer and continue to be associated with a poor prognosis. Management of brain metastases typically requires a multidisciplinary approach which may include whole-brain radiation therapy, stereotactic radiosurgery, surgery, and systemic therapy. Historically, the use of systemic therapy in brain metastases has been challenging because of the resistance to conventional chemotherapies secondary to the blood-brain barrier and an often heavily pre-treated patient population, and the paucity of well-conducted randomized trials in these heterogeneous patient populations. Newer agents, including immunotherapy and targeted therapies, are playing increasingly important roles in the up-front management of brain metastases. In this overview, we review recent advances in systemic therapies for brain metastases and the evidence supporting their use in this patient population.

Combination of anti-VEGF therapy and temozolomide in two experimental human glioma models.

Anti-angiogenic agents, such as bevacizumab (BEV), can induce normalization of the blood brain barrier, which may influence the penetration and activity of a co-administered cytotoxic drug. However, it is unknown whether this effect is associated with a benefit in overall survival. This study employed intracranial human glioma models to evaluate the effect of BEV alone and in combination with temozolomide (TMZ) and/or radiation therapy (XRT) on overall survival. One hundred eight male athymic rats were intracranially injected with either U251 or U87 human glioma. Ten or eleven days after tumor inoculation, animals bearing U251 and U87, respectively, were treated with: TMZ alone (50 mg/kg for 5 consecutive days, P.O.), BEV alone (15 mg/kg, I.V.), a combination of TMZ and BEV, or a combination of TMZ, BEV, and a single fraction of XRT (20 Gy). Controls received no treatment. The U87 experiment was repeated and the relationship between survival and the extent of anti-angiogenesis via anti-laminin antibodies for the detection of blood vessels was assessed. In both U87 glioma experiments, all of the treatment groups had a statistically significant increase in survival as compared to the control groups. Also, for both U87 experiments the combination groups of TMZ and BEV had significantly better survival when compared to either treatment administered alone, with 75% of animals demonstrating long-term survival (LTS) (defined as animals alive 120 days after tumor implantation) in one experiment and 25% LTS in the repeat experiment. In the U251 glioma experiment, all treated groups (except BEV alone) had significantly improved survival as compared to controls with minimal statistical variance among groups. The percent vessel area was lowest in the group of animals treated with BEV alone. The addition of BEV to TMZ and/or XRT had variable effect on prolonging survival in the two human glioma models tested with reduced tumor vascularity in groups treated with BEV. These results indicate that BEV has anti-angiogenic activity and does not seem to hinder the effect of TMZ.

The impact of bevacizumab on temozolomide concentrations in intracranial U87 gliomas.

PURPOSE: An important question in the sequencing of anti-cancer therapies in patients with glioblastoma (GBM) is whether concurrent anti-angiogenesis therapies improve or impair brain concentrations of concomitantly administered cytotoxic therapies. The purpose of this study is to assess the intratumoral disposition of temozolomide (TMZ) via microdialysis before and after bevacizumab in an intracranial GBM xenograft model. METHODS: Microdialysis probes were placed within tumor and contralateral brain in athymic rats bearing U87 intracerebral gliomas. TMZ (50 mg/kg oral) was administered 10 days thereafter. Extracellular fluid (ECF) was collected for 6 h. BEV was administered (10 mg/kg IV), and TMZ was re-dosed (50 mg/kg oral) 36 h thereafter with additional ECF collection. All ECF samples were assessed for TMZ concentration with liquid chromatography-tandem mass spectrometry. RESULTS: Tumor TMZ mean area under the concentration-time curve (AUC(0-∞)) was 3.35 µg h/mL pre-BEV. Post-BEV, tumor mean TMZ AUC(0-∞) was 3.98 µg h/mL. In non-tumor brain, mean TMZ AUC(0-∞) pre-BEV was 3.22 µg h/mL and post-BEV was 3.34 µg h/mL. CONCLUSIONS: There were no statistically significant changes in TMZ pharmacokinetics before or after BEV in the athymic rat U87 intracranial glioma model. BEV and TMZ are being investigated as a combination therapy in several ongoing studies for patients with glioma. These data reassuringly suggest that BEV does not significantly change the ECF tumor concentrations of TMZ in either tumor-bearing or normal brain when dosed 36 h prior to TMZ.

The toxicity of intrathecal bevacizumab in a rabbit model of leptomeningeal carcinomatosis.

UNLABELLED: Leptomeningeal carcinomatosis (LC) is a devastating complication of cancer. Intrathecal administration of cytotoxic chemotherapy adds little to survival which is measured in weeks. The potential toxicities and efficacy of intrathecally administered anti-angiogenic agents in this setting have not previously been explored. A well-characterized animal model was used to evaluate the neurotoxicity of intraventricularly administered bevacizumab (BCM). Thirty-three New Zealand White Rabbits were studied. Subcutaneous reservoirs and ventricular catheters (SRVC) were placed in eight rabbits, which were randomized to receive weekly intraventricular saline with or without BCM for four weeks. These rabbits were euthanized on day 36 and the brains were examined by a blinded neuropathologist. Twenty-five additional rabbits underwent cisternal injection of VX2 carcinoma cells with or without a single dose of BCM and were followed for survival. No clinical manifestations of neurotoxicity were noted in rabbits treated with intraventricular BCM. Similarly, no evidence of BCM neurotoxicity was identified in autopsied animals. The median survival of evaluable rabbits with LC treated with intraventricular saline (N = 13) was 15 days compared to 18 days for the animals receiving VX2 and one dose of BCM (N = 12). CONCLUSION: Intraventricular BCM can be administered to rabbits without clinical or pathologic neurotoxicity. Survival following one dose of BCM in rabbits with LC should be cautiously interpreted given uncertainties regarding the dose, schedule, and limited expected benefit of this non-rabbit antibody. This neurotoxicity study provides safety data to allow phase I/II studies in humans with treatment refractory LC.

A novel diketopiperazine stimulates sprouting of spinally projecting axons.

Following spinal cord injury, spared axonal projections undergo spontaneous compensatory sprouting in an attempt to reinnervate synaptic targets that were deinnervated as a result of injury. However, compensatory sprouting is hindered by the expression of a myriad of inhibitory molecules throughout the adult central nervous system, including chondroitin sulfate proteoglycans (CSPGs) and myelin associated inhibitory proteins (MAIPs). In this study, we have identified a diketopiperazine designated DKP101516 that can overcome the inhibitory effects of MAIPs and CSPGs on neurite outgrowth and branching. In vivo analysis demonstrates that DKP101516 enhances the plasticity of various axonal populations following septuple dorsal rhizotomy by overcoming the inhibitory effects of CSPGs and MAIPs. Our results suggest that DKP101516 may encourage spinal cord repair by stimulating compensatory sprouting of intact axonal projections.

Biomimetic synthesis of the IDO inhibitors exiguamine A and B.

Biomimetic synthesis is an attempt to assemble natural products along biosynthetic lines without recourse to the full enzymatic machinery of nature. We exemplify this with a total synthesis of exiguamine A and the newly isolated natural product exiguamine B. The most noteworthy feature of this work is an oxidative endgame drawing from the complex chemistry of catecholamines, which allows for ready access to a new class of nanomolar indoleamine-2,3-dioxygenase inhibitors.

The search for novel human pancreatic alpha-amylase inhibitors: high-throughput screening of terrestrial and marine natural product extracts.

Specific inhibitors of human pancreatic alpha-amylase (HPA) have potential as oral agents for the control of blood glucose levels in the treatment of diabetes and obesity. In a search for novel inhibitors, a library of 30 000 crude biological extracts of terrestrial and marine origin has been screened. A number of inhibitory extracts were identified, of which the most potent was subjected to bioassay-guided purification. A family of three glycosylated acyl flavonols, montbretins A-C, was thereby identified and characterized as competitive amylase inhibitors, with K(i) values ranging from 8.1-6100 nM. Competitive inhibition by myricetin, which corresponds to the flavone core, and noncompetitive inhibition by a second fragment, ethyl caffeiate, suggest a binding mode for these inhibitors.

A high-throughput screen to identify novel compounds to promote neurite outgrowth.

Following spinal cord injury, a variety of inhibitory molecules hinder the success of axon regeneration. The motile tip of the axon, the growth cone, shares a similar cytoskeletal array as a migrating cell, and in general the cytoskeleton is regulated by a conserved set of signaling pathways that act downstream of guidance cue and growth factor receptors. We exploit these similarities by using migrating cells as a model system to screen for extracts that promote axon outgrowth. The screen is a high-throughput wound-healing assay performed by a 96-pin tool Biogrid robot where positive candidates are identified as extracts that stimulate complete wound healing. Testing of positive candidates on chick DRG explants has lead to the identification of extracts that promote neurite outgrowth on permissive and inhibitory substrates. Extracts can be fractionated to purity, identifying novel compounds that promote neurite outgrowth on inhibitory substrates.

Inhibition of the G2 DNA damage checkpoint by oliveroline isolated from Duguetia odorata.

Plant extracts obtained from the U.S. National Cancer Institute's Open Repository collection have been screened for their ability to inhibit the G2 DNA damage checkpoint. An extract of Duguetia odorata showed promising activity in the assay. Bioassay-guided fractionation revealed that oliveroline (1) was responsible for the G2 checkpoint inhibitory activity of the D. odorata extract. The new alkaloid N-methylguatterine (2) was identified during this investigation.

Exiguamine A, an indoleamine-2,3-dioxygenase (IDO) inhibitor isolated from the marine sponge Neopetrosia exigua.

Exiguamine A (1), a hexacyclic alkaloid with an unprecedented skeleton, has been isolated from the marine sponge Neopetrosia exigua collected in Papua New Guinea. The structure of exiguamine A (1) was elucidated by a combination of spectroscopic analysis and single-crystal X-ray diffraction analysis. Exiguamine A (1) has a Ki of 210 nM for inhibition of indoleamine-2,3-dioxygenase (IDO) in vitro, making it one of the most potent IDO inhibitors known to date. A putative biogenesis for the new exiguamine skeleton starts from DOPA, tryptophan, and N,N-dimethylhydantoin.