Oxford's clinical experience in the development of high intensity focused ultrasound therapy

High Intensity Focused Ultrasound (HIFU) capably bridges the disciplines of surgery, oncology and biomedical engineering science. It provides the precision associated with a surgical tool whilst remaining a truly non-invasive technique. Oxford has been a centre for both clinical and preclinical research in HIFU over the last twenty years. Research into this technology in the UK has a longer history, with much of the early research being carried out by Professor Gail ter Haar and her team at the Institute of Cancer Research at Sutton in Surrey. A broad range of potential applications have been explored extending from tissue ablation to novel drug delivery. This review presents Oxford's clinical studies and applications for the development of this non-invasive therapy. This includes treatment of solid abdominal tumours comprising those of the liver, kidney, uterus, pancreas, pelvis and prostate. It also briefly introduces preclinical and translational works that are currently being undertaken at the Institute of Biomedical Engineering, University of Oxford. The safety, wide tolerability and effectiveness of this technology is comprehensively demonstrated across these studies. These results can facilitate the incorporation of HIFU as a key clinical management strategy.

Large-Volume Hyperthermia for Safe and Cost-Effective Targeted Drug Delivery Using a Clinical Ultrasound-Guided Focused Ultrasound Device

Lyso-thermosensitive liposomes (LTSLs) are specifically designed to release chemotherapy agents under conditions of mild hyperthermia. Preclinical studies have indicated that magnetic resonance (MR)-guided focused ultrasound (FUS) systems can generate well-controlled volumetric hyperthermia using real-time thermometry. However, high-throughput clinical translation of these approaches for drug delivery is challenging, not least because of the significant cost overhead of MR guidance and the much larger volumes that need to be heated clinically. Using an ultrasound-guided extracorporeal clinical FUS device (Chongqing HAIFU, JC200) with thermistors in a non-perfused ex vivo bovine liver tissue model with ribs, we present an optimised strategy for rapidly inducing (5-15 min) and sustaining (>30 min) mild hyperthermia (ΔT <+4°C) in large tissue volumes (≤92 cm³). We describe successful clinical translation in a first-in-human clinical trial of targeted drug delivery of LTSLs (TARDOX: a phase I study to investigate drug release from thermosensitive liposomes in liver tumours), in which targeted tumour hyperthermia resulted in localised chemo-ablation. The heating strategy is potentially applicable to other indications and ultrasound-guided FUS devices.

Ultrasound-Guided High Intensity Focused Ultrasound Ablation for Symptomatic Uterine Fibroids: Preliminary Clinical Experience

OBJECTIVE

 To evaluate the middle-term efficacy and complications of ultrasound-guided high intensity focused ultrasound (USgHIFU) for the treatment of symptomatic uterine fibroids in an NHS population.

METHODS

 A prospective observational single-center study at a single university hospital in Oxford, UK. Patients with symptomatic uterine fibroids who declined standard surgical/radiological intervention and were referred to the HIFU unit were considered for USgHIFU treatment. Clinical evaluation, adverse event monitoring, uterine fibroid symptoms and health-related quality of life questionnaire (UFS-QOL) and contrast-enhanced pelvic magnetic resonance imaging (MRI) were performed before and at regular intervals after treatment to assess patient outcome.

RESULTS

 12 of 22 referred patients underwent one session of USgHIFU ablation of 14 fibroids overall and received a two-year follow-up. No serious adverse events were reported, but a second-degree skin burn was observed in one patient who had a surgical scar from a previous caesarean section. Mean symptom severity scores (SSS-QOL) improved significantly from 56.5 ± 29.1 (SD) at baseline to 33.4 ± 23.3 (p < 0.01) at three months, 45.0 ± 35.4 (p < 0.05) at one year and 40.6 ± 32.7 (p < 0.01) at two years post-treatment. The mean non-perfused volume ratio was 67.7 ± 39.0 % (SD) in the treated fibroids (n = 14) within three months of treatment. The mean volume reduction rates of the treated fibroids were 23.3 ± 25.5 % (SD) at 3 months post-treatment (p < 0.01, n = 14), 49.3 ± 23.7 % at 12 months (p < 0.05, n = 8), and 51.9 ± 11.1 % at 24 months (p < 0.005, n = 8).

CONCLUSION

 This study demonstrates the clinical efficacy of USgHIFU ablation of uterine fibroids and the low risk of complications. We believe that this noninvasive approach may offer an alternative therapy for women with symptomatic uterine fibroids. While HIFU is fast becoming the standard of care for fibroid ablation in other countries, to our knowledge, this study is the first to present clinical experience of US-guided HIFU ablation of symptomatic uterine fibroids in an NHS population.

PLAIN LANGUAGE SUMMARY

High intensity focused ultrasound (HIFU) can be used for the noninvasive ablation of symptomatic uterine fibroids, and MR-guided treatment has already gained FDA approval. Ultrasound-guided HIFU has the advantage of offering practicalities in anesthesia and considerable cost-savings over MR-guided treatments. In this prospective study we have demonstrated the middle-term efficacy and favorable safety profile of ultrasound-guided HIFU for the treatment of symptomatic uterine fibroids for the first time in an NHS population.

Role of diffusion-weighted imaging in monitoring treatment response following high-intensity focused ultrasound ablation of recurrent sacral chordoma

Chordoma is the most common malignant tumor of the sacrum and is associated with significant neurologic morbidity. Local recurrence is very common, and the long-term prognosis is poor. High-intensity focused ultrasound (HIFU) is a noninvasive and nonionising ablative therapy that has been successful in treating other tumor types and is being evaluated as a new therapy for sacral chordoma. Contrast-enhanced magnetic resonance imaging is typically used to evaluate tumor perfusion following HIFU; however, its utility is limited in poorly perfused tumors. Diffusion-weighted imaging (DWI) provides tissue contrast based on differences in the diffusion of extracellular water without using gadolinium-based contrast agents. We present novel DWI findings following a planned partial HIFU ablation of a large sacral chordoma which had recurred after radiotherapy. Following HIFU, the treated tumor volume demonstrated loss of restriction on DWI correlating with photopenia on positron emission tomography. This suggests successful ablation and tumor necrosis. This novel finding may provide guidance for sequence selection when evaluating HIFU therapy for sacral chordoma and other tumor types for which contrast-enhanced magnetic resonance imaging may have limited utility.

Urological Nephrectomies for Benign Disease: A Possible Missed Resource in Organ Donation

OBJECTIVES

The deficit of organs for renal transplant is a global issue. The United Kingdom Hospital Episode Statistics indicates there that were 8168 nephrectomies undertaken in 2014. Furthermore, according to the British Association of Urological Surgeons 2014 nephrectomy report, 71.8% of patients undergoing a nephrectomy had creatinine levels of less than 120 IU/L and roughly 20% had the procedure for benign and functional causes.

MATERIALS AND METHODS

We report a prospective case series from March 2014 to March 2016 involving 6 patients showing 3 successful transplants performed following 3 native nephrectomies.

RESULTS

All recipients had normal creatinine levels with good function at 12 months, and all nephrectomy patients, in addition to maintaining normal renal function, had definitive resolution of symptoms. The main limitation of this series was the small sample size.

CONCLUSIONS

There is no doubt that all should be done to save native organ function, and all salvage procedures and psychological testing must be robust before considering this route. However, within the group that proceeds to nephrectomy, some cases may have the potential to generate a new pool of donor organs suitable for transplant, helping to tackle the organ deficit in renal transplantation.

High-intensity focused ultrasonic ablation of sacral chordoma is feasible: a series of four cases and details of a national clinical trial

High-intensity focused ultrasound describes the use of high-intensity focused ultrasound (HIFU) to ablate tumours without requiring an incision or other invasive procedure. This technique has been trialled on a range of tumours including uterine fibroids, prostate, liver and renal cancer. We describe our experience of using HIFU to ablate sacral chordoma in four patients with advanced tumours. Patients were treated under general anaesthetic or sedation using an ultrasound-guided HIFU device. HIFU therapy was associated with a reduction in tumour volume over time in three patients for whom follow up scans were available. Tumour necrosis was reliably demonstrated in two of the three patients. We have established a national trial to assess if HIFU may improve long-term outcome from sacral chordoma, details are given.

A review of high intensity focused ultrasound in relation to the treatment of renal tumours and other malignancies

For 60 years, high-intensity focused ultrasound (HIFU) has been the subject of interest for medical research. HIFU causes tissue necrosis in a very well defined area, at a variable distance from the transducer, through heating or cavitation. Over the past two decades, the use of high-intensity focused ultrasound has been investigated in many clinical settings. This review summarises recent advances made in the field of renal cancer in particular, and gives an overview on the use of the extracorporeal machines in the treatment of other malignant tumours.

Identification of a hypoxia-regulated miRNA signature in bladder cancer and a role for miR-145 in hypoxia-dependent apoptosis

BACKGROUND

Hypoxia leads to the stabilisation of the hypoxia-inducible factor (HIF) transcription factor that drives the expression of target genes including microRNAs (miRNAs). MicroRNAs are known to regulate many genes involved in tumourigenesis. The aim of this study was to identify hypoxia-regulated miRNAs (HRMs) in bladder cancer and investigate their functional significance.

METHODS

Bladder cancer cell lines were exposed to normoxic and hypoxic conditions and interrogated for the expression of 384 miRNAs by qPCR. Functional studies were carried out using siRNA-mediated gene knockdown and chromatin immunoprecipitations. Apoptosis was quantified by annexin V staining and flow cytometry.

RESULTS

The HRM signature for NMI bladder cancer lines includes miR-210, miR-193b, miR-145, miR-125-3p, miR-708 and miR-517a. The most hypoxia-upregulated miRNA was miR-145. The miR-145 was a direct target of HIF-1α and two hypoxia response elements were identified within the promoter region of the gene. Finally, the hypoxic upregulation of miR-145 contributed to increased apoptosis in RT4 cells.

CONCLUSIONS

We have demonstrated the hypoxic regulation of a number of miRNAs in bladder cancer. We have shown that miR-145 is a novel, robust and direct HIF target gene that in turn leads to increased cell death in NMI bladder cancer cell lines.

Living kidney donation following nephrectomy due to pelviureteric junction obstruction

A 49-year-old man presented with a 15-year history of problematic pelviureteric junction obstruction of his left kidney. Surgical management had failed to sufficiently control his symptoms and he was keen to have the kidney removed. Following preoperative discussion, the patient consented to his kidney being used for transplant. Following a total nephrectomy, the kidney was successfully transplanted into a 61-year-old woman, with a cold ischaemic time of 3 h and 22 min. There was primary function in the transplanted kidney and creatinine at 6 weeks was 60. This case highlights the potential for using organs with pelviureteric junction obstruction for living donor transplant and thereby expanding the donor pool.

The importance of intraoperative transoesophageal monitoring when operating on renal cancers that involve the right atrium

The surgical treatment of advanced renal cancers is challenging. Renal cell carcinoma is interesting in that it invades the vasculature and can extend up as far as the right atrium. Extension of tumour thrombus into the right atrium represents level IV disease, according to Robson staging. Transoesophageal echocardiography is useful for diagnostic purposes. It is also of great value for intraoperative cardiac monitoring and to confirm the extent of vascular involvement.

Changing prognosis of renal cell carcinoma: a single-centre experience over 25 years

Objective:

The objective of this research is to examine renal cancer nephrectomies over 25 years in our centre and the factors underlying changes in disease-specific survival.

Patients and methods:

Retrospective data analysis was performed on all patients undergoing nephrectomies at our institution for renal cell carcinoma (RCC) from 1983 to 2007. Data extracted from the Cancer Research Uro-Oncology Database (CRUD©) provided survival, clinical and prognostic information including tumour diameter, Fuhrman grade, WHO staging and age.

Results:

Analysis of 664 RCCs demonstrated a clear change in kidney cancer-specific survival over the past 25 years, with five-year survival improving from 42% (1983–1986) to 73% (1999–2002). The number of RCC nephrectomies has increased 10 fold. There was no significant change in operative mortality, age, grade, stage or mean tumour size. However, there was a five-fold increase in tumours <6 cm, corresponding to an equal-fold decrease in tumours 6–8 cm, but no change in tumours >8 cm. Tumour size >8 cm was a significant adverse prognostic marker.

Conclusions:

A 30% improvement in RCC cancer-specific survival has been seen in our centre over the last 25 years. This change relates to a shift to smaller tumours, lower histological grades and a higher volume of cases.

CD31 angiogenesis and combined expression of HIF-1α and HIF-2α are prognostic in primary clear-cell renal cell carcinoma (CC-RCC), but HIFα transcriptional products are not: implications for antiangiogenic trials and HIFα biomarker studies in primary CC-RCC

Hypoxia-inducible factors, HIF-1α and HIF-2α, are expressed in the majority of clear-cell renal cell carcinoma (CC-RCC). In vitro, HIFα isoforms regulate a differential set of genes, and their effects in vivo within CC-RCC tumours may affect outcome. The role of angiogenesis and HIFα transcriptional products, including those involved in cell metabolism and morphological dedifferentiation have not been extensively investigated and might have relevance to the development of antiangiogenic or anti-HIFα trials in primary CC-RCC, either before or after radical nephrectomy. We analysed 168 consecutive clear-cell renal tumours from 1983 to 1999 within tissue microarrays and assessed expression of HIF-1α and HIF-2α together with the protein expression of seven of their target genes (BNIP3, CA9, Cyclin D1, GLUT-1, LDH5, Oct-4 and VEGF). The expression of these factors was compared with patient overall survival and CD31 angiogenesis. We found that HIFα antigenicity deteriorated with the age of the paraffin block (P < 0.0001) and in tumours from 1983 to 1992 was deemed not to be reliable. Similar findings were found in aged archival osteosarcoma samples. This might have important implications for retrospective biomarker studies that rely on archival tissue material. HIF-1α(HIGH)/HIF-2α(LOW) tumours had a worse overall survival compared with HIF-1α(LOW)/HIF-2α(LOW) tumours (P = 0.04). Surprisingly, on multivariate analysis, high levels of CD31(+) angiogenesis was shown to be an independent prognostic marker of increased overall survival (P = 0.003). We propose that better differentiation of vascular endothelium may be a reflection of a greater production of vessel stabilization factors versus pro-angiogenic factors, and therefore a less aggressive phenotype.

High-intensity focused ultrasound treatment of liver tumours: post-treatment MRI correlates well with intra-operative estimates of treatment volume

OBJECTIVES

To assess the safety and feasibility of high-intensity focused ultrasound (HIFU) ablation of liver tumours and to determine whether post-operative MRI correlates with intra-operative imaging.

METHODS

31 patients were recruited into two ethically approved clinical trials (median age 64; mean BMI 26 kg m(-2)). Patients with liver tumours (primary or metastatic) underwent a single HIFU treatment monitored using intra-operative B-mode ultrasound. Follow-up consisted of radiology and histology (surgical trial) or radiology alone (radiology trial). Radiological follow-up was digital subtraction contrast-enhanced MRI.

RESULTS

Treatment according to protocol was possible in 30 of 31 patients. One treatment was abandoned because of equipment failure. Transient pain and superficial skin burns were seen in 81% (25/31) and 39% (12/31) of patients, respectively. One moderate skin burn occurred. One patient died prior to radiological follow-up. Radiological evidence of ablation was seen in 93% (27/29) of patients. Ablation accuracy was good in 89% (24/27) of patients. In three patients the zone of ablation lay ≤2 mm outside the tumour. The median cross-sectional area (CSA) of the zone of ablation was 5.0 and 5.1 cm(2) using intra-operative and post-operative imaging, respectively. The mean MRI:B-mode CSA ratio was 1.57 [95% confidence interval (CI)=0.57-2.71]. There was positive correlation between MRI and B-mode CSA (Spearman's r=0.48; 95% CI 0.11-0.73; p=0.011) and the slope of linear regression was significantly non-zero (1.23; 95% CI=0.68-1.77; p<0.0001).

CONCLUSIONS

HIFU ablation of liver tumours is safe and feasible. HIFU treatment is accurate, and intra-operative assessment of treatment provides an accurate measure of the zone of ablation and correlates well with MRI follow-up.

Active surveillance of small renal masses offers short-term oncological efficacy equivalent to radical and partial nephrectomy

Study Type - Therapy (case series) Level of Evidence 4. What's known on the subject? and What does the study add? Active surveillance of small renal masses has traditionally been reserved for elderly patients deemed unfit for surgery or ablation. There is increasing evidence showing the safety of active surveillance in the management of small renal masses. In this retrospective study we compared outcomes for patients with small renal masses managed with active surveillance, radical nephrectomy and partial nephrectomy. We showed that active surveillance was safe and appeared as effective as immediate surgery in the management of small renal tumours.

OBJECTIVE

• To compare the oncological outcomes of active surveillance (AS), radical nephrectomy (RN) and partial nephrectomy (PN) in the management of T1a small renal masses (SRMs).

PATIENTS AND METHODS

• At present AS is used in the treatment of SRMs in elderly patients with multiple co-morbidities or in those who decline surgery. • We identified all patients with T1a SRMs managed with RN, PN or AS. • Retrospective data were collected from patient case records with survival data and cause of death cross-referenced with the Oxford Cancer Intelligence Unit.

RESULTS

• A total of 202 patients with 234 T1a SRMs (solid or Bosniak IV) were identified; 71 patients were managed with AS, 41 with an RN and 90 by PN. • Over a median follow-up of 34 months the mean growth rate on AS was 0.21 cm/year with 53% of SRMs managed with AS showing negative or zero growth. • No statistically significant difference was observed in overall (OS) and cancer-specific (CSS) survival for AS, RN and PN (AS-CSS 98.6%, AS-OS 83%; RN-CSS 92.6%, RN-OS 80.4%; PN-CSS 96.6%, PN-OS 90.0%).

CONCLUSIONS

• Active surveillance of SRMs offers oncological efficacy equivalent to surgery in the short/intermediate term. • The results of this study support a multicentre prospective randomized controlled trial designed to compare the oncological efficacy of AS and surgery.

Abstract 3942: The role of vHL and REDD1 in predicting sensitivity to targeted therapies in renal cell carcinoma

There are currently 6 FDA approved therapies in metastatic renal cell carcinoma and their introduction has improved both time to progression and survival in these patients. Despite treatment with targeted therapies approximately 20% of patients do not respond and the remaining patients will most likely develop resistance during the first 18 months of treatment. The aim of this study was to identify a link between differences in sensitivity to targeted therapies, the vHL status and the expression of genes involved in the mTOR pathway in both historic and primary renal cancer cell lines. Drug sensitivity and gene expression data was analysed in 6 historic and 10 primary renal cancer cell lines obtained from nephrectomy specimens. Gene expression data was also available from an additional 68 renal tumours. We found that cell lines with mutated or absent vHL showed increased sensitivity to rapamycin (p&lt;0.01) but not to other therapies. Gene expression data showed that the expression of REDD1 (regulated in development and DNA damage responses 1), a known HIF1 target gene which inhibits the mTORC1 pathway in response to hypoxic stress correlates with rapamycin sensitivity (R-squared = 0.64, p=0.05). REDD1 expression was also higher in renal tumours when compared with matched normal tissue (p&lt;0.01) and was found to correlate with CAIX expression (R-squared = 0.47, p&lt;0.01). CAIX expression is associated with reduced survival in renal cell carcinoma and so further analysis is being performed to establish a potential role of REDD1 as a prognostic marker. Our findings suggest that vHL status and the levels of REDD1 expression in renal cancer cell lines can predict sensitivity to rapamycin.

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 3942. doi:1538-7445.AM2012-3942

A lucky fall? Case report

Renal cell carcinomas (RCCs) account for 3% of all solid neoplasms, with an increased incidence after renal transplantation. In transplant recipients, RCCs predominantly occur in the patient's native kidneys. Herein is reported a case of a localized RCC of recipient origin that developed in the donor allograft and was detected 8 years after renal transplantation. Treatment with high-intensity focussed ultrasound followed by partial nephrectomy was successful, averting the need for dialysis therapy.

Extracorporeal high intensity focused ultrasound for renal tumours: a 3-year follow-up

OBJECTIVE

To determine whether primary extracorporeal high-intensity focused ultrasound (HIFU) is safe, feasible and effective for managing small renal tumours.

PATIENTS AND METHODS

Although surgery currently remains the standard treatment for localized renal cell carcinoma (RCC), the increasing incidence of small renal cancers has led to a shift towards nephron-sparing surgery, with associated morbidity in 20-25% of cases, and minimally invasive ablative therapies present an alternative management. HIFU results in 'trackless' homogenous tissue ablation and when administered via an extracorporeal device, is entirely noninvasive. The study comprised 17 patients (mean tumour size 2.5 cm) with radiologically suspicious renal tumours who underwent extracorporeal HIFU using the Model-JC System (Chongqing HAIFU™, China), under general anaesthesia with one overnight hospital stay. Real-time diagnostic ultrasonography was used for targeting and monitoring. Patients were followed with a clinical review and gadolinium-enhanced magnetic resonance imaging at 12 days and every 6 months for a mean of 36 months. The outcomes measures were patient morbidity and oncological efficacy of HIFU treatment.

RESULTS

Of the 17 patients, 15 were treated according to protocol; two procedures were abandoned due to intervening bowel. There were no major complications related to HIFU. Radiological evidence of ablation was apparent at 12 days in seven of the 15 patients. Before the 6-month follow-up one patient had surgery due to persisting central enhancement. Fourteen patients were evaluated at the 6-month follow-up; eight tumours had involuted (mean 12% decrease in tumour area). Four patients had irregular enhancement on imaging and had alternative therapies. Ten patients remain on follow-up at a mean (range) of 36 (14-55) months after HIFU (mean 30% decrease in tumour area). There was central loss of enhancement in all.

CONCLUSIONS

Renal HIFU achieves stable lesions in two-thirds of patients, with minimal morbidity, and might be appropriate in selected cases. Further trials with accurate histological follow-up are essential to fully evaluate this novel technique.