Incomplete thermal ablation stimulates proliferation of residual renal carcinoma cells in a translational murine model

Potential of Thermal Ablation Combined with Immunotherapy in Peripheral Lung Tumors: A Review and Prospect

BACKGROUND

Lung tumors are prevalent malignancies associated with a high mortality rate, imposing significant medical and societal burdens. Although immunotherapy shows promise in improving survival, response rates are relatively modest. Thermal ablation can not only eliminate tumor cells directly but also enhance antitumor immunity response, thus manifesting a remarkable propensity to synergize with immunotherapy.

SUMMARY

In this review, we provided a brief overview of the application of thermal ablation in peripheral lung tumors. We summarized the patient selection of thermal ablation. We highlighted the potential of thermal ablation to augment the antitumor immune response, offering a promising avenue for combined therapies. We summarized studies assessing the synergistic effects of thermal ablation and immunotherapy in preclinical and clinical settings. Lastly, we underscored the urgent issues that warrant in-depth exploration when applying thermal ablation and immunotherapy to lung tumor patients.

KEY MESSAGES

This review emphasized the prospects of using thermal ablation combined with immunotherapy in patients with peripheral lung tumors. However, further research is needed to enhance and optimize this treatment strategy.

Combining energy-based focal ablation and immune checkpoint inhibitors: preclinical research and clinical trials

Energy-based focal therapy (FT) uses targeted, minimally invasive procedures to destroy tumors while preserving normal tissue and function. There is strong emerging interest in understanding how systemic immunity against the tumor can occur with cancer immunotherapy, most notably immune checkpoint inhibitors (ICI). The motivation for combining FT and ICI in cancer management relies on the synergy between the two different therapies: FT complements ICI by reducing tumor burden, increasing objective response rate, and reducing side effects of ICI; ICI supplements FT by reducing local recurrence, controlling distal metastases, and providing long-term protection. This combinatorial strategy has shown promising results in preclinical study (since 2004) and the clinical trials (since 2011). Understanding the synergy calls for understanding the physics and biology behind the two different therapies with distinctive mechanisms of action. In this review, we introduce different types of energy-based FT by covering the biophysics of tissue-energy interaction and present the immunomodulatory properties of FT. We discuss the basis of cancer immunotherapy with the emphasis on ICI. We examine the approaches researchers have been using and the results from both preclinical models and clinical trials from our exhaustive literature research. Finally, the challenges of the combinatory strategy and opportunities of future research is discussed extensively.

Impact of Endoluminal Radiofrequency Ablation on Immunity in Pancreatic Cancer and Cholangiocarcinoma

Radiofrequency ablation (RFA) is a mini-invasive loco-regional ablation technique that is increasingly being used as a palliative treatment for pancreatic cancer and cholangiocarcinoma. Ablation-triggered immune system stimulation has been proposed as a mechanism behind the systemic effects of RFA. The aim of our study was to investigate the immune response to endoluminal biliary RFA. Peripheral blood samples were collected from patients with pancreatic cancer and cholangiocarcinoma randomised to receive endoluminal biliary radiofrequency ablation + stent (19 patients) or stent only (21 patients). We observed an early increase in IL-6 levels and a delayed increase in CXCL1, CXCL5, and CXCL11 levels as well as an increase in CD8+ and NK cells. However, these changes were not specific to RFA treatment. Explicitly in response to RFA, we observed a delayed increase in serum CXCL1 levels and an early decrease in the number of anti-inflammatory CD206+ blood monocytes. Our study provides the first evidence of endoluminal biliary RFA-based regulation of the systemic immune response in patients with pancreatic cancer and cholangiocarcinoma. These changes were characterised by a general inflammatory response. RFA-specific activation of the adaptive immune system was not confirmed.

Graphene-containing metal-organic framework nanocomposites for enhanced microwave ablation of salivary adenoid cystic carcinoma

Salivary adenoid cystic carcinoma (SACC), one of the most common malignant tumors in the head and neck region, is characterized by high postoperative recurrence rate and poor prognosis. Microwave (MW) ablation possesses advantages in preserving SACC patients' facial aesthetics and oral function, but unfortunately, it suffers from low therapeutic efficacy due to the limited MW-thermal efficiency. Moreover, the insufficient thermal ablation may aggravate hypoxic state in tumors, which is deleterious to the treatment of residual tumors and aggressive tumors. Hence, MW ablation has been rarely applied in treating head and neck tumors in recent years. To minimize the unfavorable outcomes and maximize the therapeutic effects of MW ablation, a MW sensitizer coupled with a self-sufficient oxygen nanoagent was employed for the first time in MW ablation to treat head and neck tumors. We prepared a graphene-containing metal-organic framework (ZIF67@Gr-PEG), which exhibited excellent MW thermal conversion ability endowed by the incorporated Gr and showed in situ oxygen generation capacity derived from the ZIF67 matrix. In an animal experiment, ZIF67@Gr-PEG-based MW ablation with a temperature up to 66.1 °C exhibited a high tumor ablation rate. More importantly, insufficient MW ablation-induced high expressions of HIF-1α and VEGF were observed in our experiment, whereas the levels of tumor hypoxia and angiogenesis were efficiently decreased in MW ablation with the assistance of ZIF67@Gr-PEG nanocomposites (NCs). Notably, our strategy for MW ablation not only evidences the great potential of ZIF67@Gr-PEG but also promotes the translation of thermotherapeutic graphene from basic research to clinical practice.

Radiofrequency ablation triggers the migration of hepatocellular carcinoma cells by suppressing miR-148a-5p

Increasing evidences suggest that insufficient radiofrequency ablation (IRFA) can paradoxically promote tumor invasion and metastatic processes, whereas the effects of moderate hyperthermia on cancer progression are not well illustrated. Our study found that IRFA can increase the in vitro migration, invasion, and epithelial-mesenchymal transition (EMT) of hepatocellular carcinoma (HCC) cells via induction of Snail, a master regulator of EMT events. Among measured miRNAs, IRFA can decrease the expression of miR-148a-5p in HCC cells. Whereas overexpression of miR-148a-5p can reverse IRFA-induced migration of HCC cells and upregulation of Snail, mechanistically overexpression of miR-148a-5p can directly target and decrease the expression of protein kinase ATM (ataxia telangiectasia mutated), which can increase protein stability of Snail. Collectively, our data suggest that IRFA can regulate the miR-148a-5p/ATM/Snail axis to trigger migration of HCC cells.

Radiation exposure triggers the malignancy of non‑small cell lung cancer cells through the activation of visfatin/Snail signaling

It is estimated that one-half of patients with non-small cell lung cancer (NSCLC) undergo radiotherapy worldwide. However, the outcome of radiotherapy alone is not always satisfactory. The aim of the present study was to evaluate the effects of radiotherapy on the malignancy of NSCLC cells. It was demonstrated that radiation therapy could increase the migration and invasion of NSCLC cells in vitro. Moreover, the upregulation of visfatin, a 52-kDa adipokine, mediated radiation-induced cell motility. A neutralizing antibody specific for visfatin blocked radiation-induced cell migration. Radiation and visfatin induced the expression of Snail, a key molecule that regulates epithelial to mesenchymal transition in NSCLC cells. Furthermore, visfatin positively regulated the mRNA stability of Snail in NSCLC cells, but had no effect on its protein degradation. This may be explained by visfatin-mediated downregulation of microRNA (miR)-34a, which was shown to bind the 3′ untranslated region of Snail mRNA to promote its decay. Collectively, these findings suggested that radiation could induce cell motility in NSCLC cells through visfatin/Snail signaling.

[Thermoablation : Friend and foe of immunotherapy]

BACKGROUND

Evidence from multiple studies have shown the potential of thermal ablative therapies to induce regression of metastases and tumors which are distant from the treated metastases-within the same organ or even in other organs-the so-called abscopal effect. Unfortunately, this effect is most often weak and not always reproducible. Recent developments in systemic therapies showed that immunomodulating drugs are of major interest in patient-tailored tumor therapy due to the fact that they are able to enhance the treatment effect of conventional chemotherapy. Furthermore, several studies and reports showed that these immunomodulating therapies are also able to enhance the response of the immune system to the tumor-if combined with local ablative therapies-and trigger a systemic antitumor response. Unfortunately, there is also evidence that effects caused by thermal ablation can hamper the immune system and, therefore, increase tumor growth and tumor spread.

OBJECTIVES

In this article, the effects of thermal ablation in general are described, different (thermo-)ablative techniques are presented and a perspective of combination therapies is given.

Follow-up imaging after cryoablation of clear cell renal cell carcinoma is feasible using single photon emission computed tomography with 111In-girentuximab

Purpose

Detection of residual or recurrent vital renal tumor on follow-up (FU) cross-sectional imaging after ablative therapy is challenging. The specific and high expression levels of carbonic anhydrase IX (CAIX) in clear cell renal cell carcinoma (ccRCC) makes it a suitable target for imaging using radiolabeled anti-CAIX antibody girentuximab. The objective of this study was to evaluate the feasibility of targeted FU imaging 1 month after cryoablation of ccRCC using single photon emission computed tomography (SPECT) after ¹¹¹In-labeled girentuximab administration.

Methods

In this prospective study 16 patients underwent ¹¹¹In-girentuximab-SPECT before MR-guided renal cryoablation between February 2015 and September 2018. In case of tumor targeting ¹¹¹In-girentuximab-SPECT was repeated 1 month following MR-guided cryoablation. Presence of residual or recurrent vital tumor was assessed on contrast-enhanced cross-sectional imaging during further FU. The standard FU imaging protocol consisted of MRI/CT scans at 1, 3, 6, 12, and 18 months and annually thereafter.

Results

A total of 10 (63%) patients showed positive tumor targeting on ¹¹¹In-girentuximab-SPECT before cryoablation and 9 ( 56%) were eligible to undergo FU SPECT. Of the 9 ¹¹¹In-girentuximab-SPECT FU scans, 8 (89%) were considered negative. One (11%) scan showed uptake suggestive for residual vital tumor. Six months after treatment, FU CT showed contrast enhancement suggestive for residual/recurrent disease in the ablated zone at the site of the ¹¹¹In-girentuximab uptake after treatment. During a mean FU of 21 months (range 1–33) no other cases with residual/recurrent disease were detected.

Conclusion

FU imaging with ¹¹¹In-girentuximab-SPECT is feasible after ccRCC cryoablation and may contribute to early detection of residual or recurrent disease.

Postablation Immune Microenvironment: Synergy between Interventional Oncology and Immuno-oncology

Current tumor thermal ablation techniques rely on extreme temperatures to induce irreversible cellular injury and coagulative tissue necrosis. Ablation-induced cellular injury or death releases cancer neoantigens and activates the cancer-immunity cycle, potentially generating tumor-specific immune effectors. However, multiple negative regulatory modulators exist at each step of the cycle, mitigating meaningful and therapeutic anticancer effect provided by the immune system. Recent studies have focused on the introduction and testing of adjuvant immunotherapy combined with ablation to synergistically shift the equilibrium out of inhibitory immune modulation. This article reviews the immune microenvironment in relation to image-guided ablation techniques and discusses current and upcoming novel strategies to take advantage of antitumor immunity.

Boiling Histotripsy Ablation of Renal Cell Carcinoma in the Eker Rat Promotes a Systemic Inflammatory Response

Boiling histotripsy (BH) is an experimental focused ultrasound technique that produces non-thermal mechanical ablation. We evaluated the feasibility, short-term histologic effects and the resulting acute inflammatory response to BH ablation of renal cell carcinoma (RCC) in the Eker rat. Genotyped Eker rats were monitored for de novo RCCs with serial ultrasound (US) imaging. When tumors were ≥8 mm, rats underwent ultrasound-guided extracorporeal ablation of the tumor with BH, a pulsed focused US technique that produces non-thermal mechanical ablation of targeted tissues, or a sham US procedure. Treatments targeted approximately 50% of the largest RCC with a margin of normal kidney. BH treated rats were euthanized at 1 (n = 4) or 48 (n = 4) h, and sham patients (n = 4) at 48 h. Circulating plasma cytokine levels were assessed with multiplex assays before and at 0.25, 1, 4, 24 and 48 h following treatment. Kidneys were collected and processed for histologic assessment, immunohistochemistry and intrarenal cytokine concentration measurements. For statistical analysis Student's t-test was used. US-guided BH treatment was successful in all animals, producing hypoechoic regions within the targeted volume consistent with BH treatment effect. Grossly, regions of homogenized tissue were apparent with evidence of focal intra-parenchymal hemorrhage. Histologically, BH produced a sharply demarcated region of homogenized tumor and non-tumor tissue containing acellular debris. BH treatment was associated with significantly increased relative concentration of plasma TNF versus sham treatment (p < 0.05) and transient elevations in high-mobility group box 1 (HMGB1), IL-10 and IL-6 consistent with acute inflammatory response to trauma. Intrarenal cytokine concentrations followed the same trend. At 48 h, enhanced infiltration of CD8+ T cells was observed by immunohistochemistry in both the treated and un-treated contralateral RCC/kidneys in BH-treated animals versus sham treatment. BH treatment was well tolerated with transient gross hematuria and a perinephric hematoma developing in one subject each. The study demonstrates the feasibility of BH ablation of de novo RCC and suggests activation of the acute inflammatory cascade following treatment that appears to stimulate CD8+ T cell infiltration of both treated and untreated tumors. Longer duration chronic studies are ongoing to characterize the longevity and robustness of this response.

Efficacy of percutaneous radiofrequency ablation may vary with clear cell renal cell cancer histologic subtype

PURPOSE

The purpose of the study is to determine if clear cell renal cell cancer (RCC) subtype predicts efficacy in percutaneous radiofrequency (RF) ablation of RCC.

METHODS AND MATERIALS

Patients who underwent percutaneous RF ablation for histologically proven RCC subtypes were retrospectively reviewed. Group comparisons were done using univariate and multivariate logistic regression analysis to determine factors impacting primary, secondary, and total technique effectiveness. A p value less than 0.05 was considered significant.

RESULTS

One hundred pathologically proven RCC lesions in 84 patients were analyzed. The median (mean) follow-up was 24 (27) months (range 1-106 months). Overall RF ablation primary, secondary and total technique effectiveness was 86%, 9%, and 95%, respectively. Clear cell subtype demonstrated worse treatment efficacy with primary, secondary, and total technique effectiveness of 42/55 (76.4%), 8/55 (14.5%), and 50/55 (90.9%), respectively. Non-clear cell subtypes had primary, secondary, and total technique effectiveness of 44/45(97.8%), 1/45 (2.2%), 45/45 (100%), respectively. The difference in primary (p = 0.002), secondary (p = 0.032), and total (p = 0.038) technique effectiveness between the two groups was statistically significant.

CONCLUSION

Clear cell RCC was a novel predictor of primary, secondary, and total technique efficacy in the percutaneous RF ablation of clear cell RCC.

Insufficient Radiofrequency Ablation Treated Hepatocellular Carcinoma Cells Promote Metastasis by Up-Regulation ITGB3

Radiofrequency ablation (RFA) is one of the standards of care for early stage hepatocellular carcinoma (HCC). However, rapid progression of residual tumor after RFA has been confirmed. The aim of this study was to investigate the underlying mechanism of this phenomenon. Human HCC cell lines HCCLM3 and HepG2 were employed to establish insufficient RFA models in vivo and in vitro, respectively. The effects of insufficient RFA on metastatic potential of residual tumors were evaluated. The molecular changes after insufficient RFA were evaluated by PCR array, western blot, immunofluorescence, and immunohistochemistry. Results showed that insufficient RFA significantly promoted lung and intrahepatic residual tumor cells in vivo, and heat intervention promoted migration and invasion of hepatoma cells in vitro. PCR array revealed that the expression of integrin β3 (ITGB3) and MMP2 were up-regulated in the residual tumors of HCCLM3 xenograft model. The up-regulation of ITGB3 was confirmed by qRT-PCR, Western blot and immunohistochemistry. Knockdown ITGB3 expression in HCCLM3 cells by shRNA significantly lowered the pro-metastatic effects of insufficient RFA. Mechanism studies indicated that ITGB3 mediated the expression of MMP2 by activing FAK/PI3K/AKT signaling pathway. The up-regulation of ITGB3 contributed to enhanced metastatic potential of residual cancer in HCCLM3 model after insufficient RFA. Targeting ITGB3 expression may further improve the clinical effects of RFA.

Long noncoding RNA expression profiles in sub-lethal heat-treated hepatoma carcinoma cells

Background

Sub-lethal heat treatment characterizes a transition zone of radiofrequency ablation (RFA) which explains hepatocellular carcinoma (HCC) residual cancer occurrence in this area after RFA treatment. The biochemistry of residual cancer cell recurrence is poorly understood, but long noncoding RNAs (lncRNAs) may have aberrant expression that is associated with diverse cancers. Thus, we measured lncRNA gene expression in sub-lethally heat-treated HCC cells using microarray.

Method

Differentially expressed lncRNA and mRNA were measured with an Agilent Human lncRNA + mRNA Array V4.0 (4 × 180 K format) containing 41,000 lncRNAs and 34,000 mRNAs. Bioinformatics analysis was used to assess differentially expressed lncRNA and mRNA. Seven lncRNA and seven mRNA were validated by qRT-PCR analysis in HCC cells.

Results

Genome-wide lncRNA and mRNA expression data in sub-lethal heat-treated SMMC-7721 HCC cells 558 lncRNA and 250 mRNA were significantly up-regulated and 224 lncRNA and 1031 mRNA down-regulated compared to normal cultured SMMC-7721 cells. We demonstrated for the first time that ENST00000570843.1, ENST00000567668.1, ENST00000582249.1, ENST00000450304.1, TCONS_00015544, ENST00000602478.1, TCONS_00001266 and ARC, IL12RB1, HSPA6 were upregulated, whereas STAT3, PRPSAP1, MCU, URB2 were down-regulated in sub-lethally heat-treated HCC cells.

Conclusions

lncRNA expression data in sub-lethally heat-treated HCC cells will provide important insights about lncRNAs’ contribution to HCC recurrence after RFA treatment.

Electronic supplementary material

The online version of this article (doi:10.1186/s12957-017-1194-4) contains supplementary material, which is available to authorized users.

Clinical outcomes of percutaneous radiofrequency ablation for small renal cancer

Partial nephrectomy is the treatment of choice for small renal cell carcinoma (RCC) from the perspective of cancer management and renal function. However, when patients with RCC are of advanced age, exhibit severe comorbidities, including cardiovascular and pulmonary diseases, or have hereditary RCC, ablative therapies, including radiofrequency ablation (RFA) and cryoablation are useful treatment options. In the present study, the clinical outcomes of percutaneous RFA for treating small RCC were evaluated. Between December 2005 and March 2015, 40 patients (41 renal tumors in total) underwent RFA and a total of 50 sessions of RFA were performed. The average tumor size was 2.5 cm. A total of 18 tumors were exophytic and 23 were parenchymal. Of the 41 tumors, 85.4% were completely ablated by initial RFA and the rate of complete ablation following reablation for residual viable lesions was 95.1%. Local recurrence-free survival following complete ablation was 84.2% at 3 years. A patient with a 4.7 cm RCC tumor rapidly progressed following four RFA treatments until complete ablation was achieved. The metastasis-free survival rate following initial RFA was 95.7% at 3 years. The RCC-specific survival was 100% (mean follow-up, 38 months). Adverse events occurred in five sessions (10%); however, only 1 patient with arteriovenous fistula required intervention (transarterial embolization). The mean hospital stay following RFA was 3.2 days. The mean decrease in estimated glomerular filtration rate following RFA was 2.7%. The results of the present study indicate that percutaneous RFA was an effective treatment for small RCCs with respect to management of cancer, minimal invasiveness and minimal loss of renal function, particularly in patients for whom surgery would be a high risk and those at increased risk of deterioration of renal function.

Multipoint Thermal Sensors Associated with Improved Oncologic Outcomes Following Cryoablation

INTRODUCTION

Cryoablation (CA) is a minimally invasive modality for the management of small renal cortical neoplasms (RCN). Effective ablation is dependent on achieving target temperatures during CA that result in tumor cell death. We investigated long-term oncologic outcomes following CA using multipoint thermal sensors (MTS), which allow precise temperature determination at four points along the needle.

METHODS

We performed a retrospective review of 20 patients with <4 cm RCN who underwent de novo CA from 2005 to 2009. In 11 procedures, MTS needles were deployed with the goal of obtaining -20°C at the tumor margin, while 9 were done without MTS. Patient demographics, tumor characteristics, and CA procedure data were retrieved and analyzed. Follow-up CT or MRI was used to assess recurrence status.

RESULTS

With a mean follow-up of 45 months, none of the 11 patients experienced a recurrence in the MTS group, compared with 4 of 9 (44.4%) patients in the non-MTS group (p = 0.026). Of the biopsy-confirmed renal cancers, none of the 6 in the MTS group, compared with 3 of 6 (50%) in the non-MTS group, recurred (p = 0.182). Age, tumor size, surgical approach, tumor histopathology, grade, follow-up time, and skin-to-tumor distance were similar between the MTS and non-MTS groups. The MTS group was also associated with increased total length of freeze (p = 0.041), procedure time (p = 0.020), cryoprobe utilization (p = 0.049), and a greater ratio of cryoprobes used per cm diameter of tumor (p = 0.003).

CONCLUSIONS

In this small renal mass pilot study, the use of MTS needles to monitor temperature and guide cryoneedle deployment was associated with improved oncologic outcomes.

Safety and effectiveness of percutaneous radiofrequency ablation in early stage renal cell carcinoma

The purpose of this study was to analyze the safety and effectiveness of percutaneous radiofrequency ablation (RFA) in early stage renal cell carcinoma. A total of 76 patients suffering from early stage renal cell carcinoma were selected and randomly assigned into the observation group (41 cases) or the control group (35 cases). Percutaneous RFA was used in the observation group, while retroperitoneoscopic radical operation of renal cell carcinoma was used in the control group, and the operative effects were compared. In the observation group, operation time, blood loss during operation, length of stay and incidence rate of complications were lower than those in control group (P<0.05). For both groups, serum C-reactive protein, interleukin-6 and T lymphocyte counts at 1, 2 and 3 days after operation were all increased; however, the control group had significantly greater increase for all the time points (P<0.05). For total effective rates, tumour-free survival times and survival rates, there were no statistically significant differences between the two groups (P>0.05). Percutaneous RFA has a reduced size of operation wound and a quick postoperative recovery time in the treatment of early stage renal cell carcinoma. It results in less inflammation and immunity-based injuries in the body and achieves the same clinical outcomes as retroperitoneoscopic radical operation of renal cell carcinoma.

MRI-guided focal laser ablation for prostate cancer followed by radical prostatectomy: correlation of treatment effects with imaging

Purpose

To correlate treatment effects of MRI-guided focal laser ablation in patients with prostate cancer with imaging using prostatectomy as standard of reference.

Methods

This phase I study was approved by the Institutional Review Board. Three weeks prior to prostatectomy, five patients with histopathologically proven, low/intermediate grade prostate cancer underwent transrectal MRI-guided focal laser ablation. Per patient, only one ablation was performed to investigate the effect of ablation on the tissue rather than the effectiveness of ablation. Ablation was continuously monitored with real-time MR temperature mapping, and damage-estimation maps were computed. A post-ablation high-resolution T1-weighted contrast-enhanced sequence was acquired. Ablation volumes were contoured and measured on histopathology specimens (with a shrinkage factor of 1.15), T1-weighted contrast-enhanced images, and damage-estimation maps, and were compared.

Results

A significant volume correlation was seen between the ablation zone on T1-weighted contrast-enhanced images and the whole-mount histopathology section (r = 0.94, p = 0.018). The damage-estimation maps and histopathology specimen showed a correlation of r = 0.33 (p = 0.583). On histopathology, the homogeneous necrotic area was surrounded by a reactive transition zone (1–5 mm) zone, showing neovascularisation, and an increased mitotic index, indicating increased tumor activity.

Conclusions

The actual ablation zone was better indicated by T1-weighted contrast-enhanced than by damage-estimation maps. Histopathology results highlight the importance of complete tumor ablation with a safety margin.

Incomplete radiofrequency ablation accelerates proliferation and angiogenesis of residual lung carcinomas via HSP70/HIF-1α

Radiofrequency ablation (RFA) therapy has been proved effective and feasible for lung cancer. However, the molecular mechanisms of local lung cancer recurrence following RFA are poorly understood. The present study aimed to evaluate the ability of HSP70/HIF-1α to affect the proliferation and angiogenesis of non-small cell lung cancers (NSCLCs) following insufficient RFA to uncover the molecular mechanisms of local recurrence. In vitro heat treatment was used to establish sublines of NCI-H1650 cells. The NCI-H1650 subline that was established by heat treatment at 54°C had a relatively higher viability and significantly elevated heat tolerance (compared to the parental strain). After treatment with the HSP70 inhibitor VER-155008, the HIF-1α inhibitor YC-1 and PI3K/Akt inhibitor wortmannin, the viability and proliferation rate of the cells was measured. At the same time, HSP70, HIF-1α and Akt were detected by real-time PCR and western blotting. In vivo xenograft tumors were created by subcutaneously inoculating nude mice with NCI-H1650 cells. HSP70, HIF-1α and Akt were detected by western blotting, and CD34 expression was detected by immunohistochemistry before and after RFA or treatment with the VER-155008, YC-1 or wortmannin inhibitors. The heat-adapted NCI-H1650 subline established in vitro had a higher viability and proliferative activity compared to parental cells. Inhibiting HSP70/HIF-1α abolished this difference. Blocking the PI3K/Akt signaling pathway decreased HSP70/HIF-1α expression levels. In vivo, we found that incomplete RFA treatment promoted HSP70/HIF-1α and CD34 expression. Additionally, the combination of RFA and treatment targeting HSP70/HIF-1α resulted in a synergistic reduction in tumor growth compared to incomplete RFA alone. The PI3K/Akt signaling pathway is also involved in regulating HSP70/HIF-1α expression during this process. We conclude that the accelerated proliferation and angiogenesis potential of residual lung carcinomas following RFA treatment was induced by HSP70/HIF-1α, expression of which is regulated by the PI3K/Akt signaling pathway.

In vivo MR guided boiling histotripsy in a mouse tumor model evaluated by MRI and histopathology

Boiling histotripsy (BH) is a new high intensity focused ultrasound (HIFU) ablation technique to mechanically fragmentize soft tissue into submicrometer fragments. So far, ultrasound has been used for BH treatment guidance and evaluation. The in vivo histopathological effects of this treatment are largely unknown. Here, we report on an MR guided BH method to treat subcutaneous tumors in a mouse model. The treatment effects of BH were evaluated one hour and four days later with MRI and histopathology, and compared with the effects of thermal HIFU (T-HIFU). The lesions caused by BH were easily detected with T2 w imaging as a hyper-intense signal area with a hypo-intense rim. Histopathological evaluation showed that the targeted tissue was completely disintegrated and that a narrow transition zone (<200 µm) containing many apoptotic cells was present between disintegrated and vital tumor tissue. A high level of agreement was found between T2 w imaging and H&E stained sections, making T2 w imaging a suitable method for treatment evaluation during or directly after BH. After T-HIFU, contrast enhanced imaging was required for adequate detection of the ablation zone. On histopathology, an ablation zone with concentric layers was seen after T-HIFU. In line with histopathology, contrast enhanced MRI revealed that after BH or T-HIFU perfusion within the lesion was absent, while after BH in the transition zone some micro-hemorrhaging appeared. Four days after BH, the transition zone with apoptotic cells was histologically no longer detectable, corresponding to the absence of a hypo-intense rim around the lesion in T2 w images. This study demonstrates the first results of in vivo BH on mouse tumor using MRI for treatment guidance and evaluation and opens the way for more detailed investigation of the in vivo effects of BH. Copyright © 2016 John Wiley & Sons, Ltd.

Hepatic Radiofrequency Ablation-induced Stimulation of Distant Tumor Growth Is Suppressed by c-Met Inhibition

PURPOSE

To elucidate how hepatic radiofrequency (RF) ablation affects distant extrahepatic tumor growth by means of two key molecular pathways.

MATERIALS AND METHODS

Rats were used in this institutional animal care and use committee-approved study. First, the effect of hepatic RF ablation on distant subcutaneous in situ R3230 and MATBIII breast tumors was evaluated. Animals were randomly assigned to standardized RF ablation, sham procedure, or no treatment. Tumor growth rate was measured for 3½ to 7 days. Then, tissue was harvested for Ki-67 proliferative indexes and CD34 microvascular density. Second, hepatic RF ablation was performed for hepatocyte growth factor (HGF), vascular endothelial growth factor (VEGF), and c-Met receptor expression measurement in periablational rim, serum, and distant tumor 24 hours to 7 days after ablation. Third, hepatic RF ablation was combined with either a c-Met inhibitor (PHA-665752) or VEGF receptor inhibitor (semaxanib) and compared with sham or drug alone arms to assess distant tumor growth and growth factor levels. Finally, hepatic RF ablation was performed in rats with c-Met-negative R3230 tumors for comparison with the native c-Met-positive line. Tumor size and immunohistochemical quantification at day 0 and at sacrifice were compared with analysis of variance and the two-tailed Student t test. Tumor growth curves before and after treatment were analyzed with linear regression analysis to determine mean slopes of pre- and posttreatment growth curves on a per-tumor basis and were compared with analysis of variance and paired two-tailed t tests.

RESULTS

After RF ablation of normal liver, distant R3230 tumors were substantially larger at 7 days compared with tumors treated with the sham procedure and untreated tumors, with higher growth rates and tumor cell proliferation. Similar findings were observed in MATBIII tumors. Hepatic RF ablation predominantly increased periablational and serum HGF and downstream distant tumor VEGF levels. Compared with RF ablation alone, RF ablation combined with adjuvant PHA-665752 or semaxanib reduced distant tumor growth, proliferation, and microvascular density. For c-Met-negative tumors, hepatic RF ablation did not increase distant tumor growth, proliferation, or microvascular density compared with sham treatment.

CONCLUSION

RF ablation of normal liver can stimulate distant subcutaneous tumor growth mediated by HGF/c-Met pathway and VEGF activation. This effect was not observed in c-Met-negative tumors and can be blocked with adjuvant c-Met and VEGF inhibitors.

Low-frequency and low-intensity ultrasound-mediated microvessel disruption enhance the effects of radiofrequency ablation on prostate cancer xenografts in nude mice

The aim of the present study was to examine the impact of low-frequency, low-intensity ultrasound (US)-stimulated microbubbles (USMB) on radiofrequency ablation (RFA) in the treatment of nude mice with human prostate cancer xenografts. The tumor‑bearing nude mice were divided into three groups: The USMB+RFA group was treated with USMB immediately followed by RFA, the RFA group was treated with RFA alone, and the control group remained untreated. The animals underwent enhanced US to calculate the tumor volumes, ablation volumes and ablation rates. Subsequently, the tumors were excised for hematoxylin and eosin staining, to identify necrosis in the tumors following the treatments, and immunohistochemical staining, to analyze the apoptotic index (AI), proliferative index (PI) and microvessel density (MVD) at 1, 4 and 7 days post-treatment. Each group contained five mice at each time‑point. Necrosis was apparent in the center of the tumors in the treatment groups. Ablation lesion volumes of the USMB+RFA group were larger than those in the RFA group at 1 and 4 days post‑treatment (P=0.002 and P=0.022, respectively), and the ablation rates of the USMB+RFA group were significantly higher, compared with the RFA group at the three time‑points (all P<0.001). There were fewer apoptotic cells and more proliferative cells in the RFA group, compared with the control group 1,4 and 7 days post‑treatment (all P<0.05). The AI of the USMB+RFA group was higher than that of the control group and lower than that of the RFA group 1 day post-treatment (P=0.034 and P=0.016, respectively). The PI of the USMB+RFA group was lower than that of the control group and higher than that of the RFA group 4 and 7 days post-treatment (all P<0.05). No significant differences were observed in MVD among the three groups throughout the experiment. In conclusion, exposure to USMB prior to RFA produced larger volumes of ablation, compared with treatment with RFA alone, and increased AI and reduced PI in the residual carcinoma cells induced by RFA.

Thermal ablation in renal cell carcinoma management: a comprehensive review

PURPOSE OF REVIEW

This article provides an overview of recent developments in the field of thermal ablation for renal cell carcinoma and focuses on current standard techniques, new technologies, imaging for ablation guidance and evaluation, and future perspectives.

RECENT FINDINGS

Emerging long-term data on cryoablation and radiofrequency ablation (RFA) show marginally lower oncologic outcomes compared to surgical treatment, balanced by better functional and perioperative outcomes. Reports on residual disease vary widely, influenced by different definitions and strategies in determining ablation failure. Stratifying disease-free survival after RFA according to tumor size suggests 3 cm to be a reasonable cut off for RFA tumor selection. Microwave ablation and high-intensity focal ultrasound are modalities with the potential of creating localized high temperatures. However, difficulties in renal implementation are impairing sufficient ablation results. Irreversible electroporation, although not strictly thermal, is a new technology showing promising results in animal and early human research.

SUMMARY

Although high-level randomized controlled trials comparing thermal ablation techniques are lacking, evidence shows that thermal ablation for small renal masses is a safe procedure for both long-term oncologic and functional outcomes. Thermal ablation continues to be associated with a low risk of residual disease, for which candidates should be properly informed. RFA and cryoablation remain the standard techniques whereas alternative techniques require further studies.

Hybrid paclitaxel and gold nanorod-loaded human serum albumin nanoparticles for simultaneous chemotherapeutic and photothermal therapy on 4T1 breast cancer cells

The use of human serum albumin nanoparticles (HSAPs) as a drug carrier system for cancer treatment has proven successful through current marketable clinical formulations. Despite this success, there is a current lack of multifunctional HSAPs, which offer combinational therapies of more than one proven technique. Gold nanorods (AuNRs) have also shown medicinal promise due to their photothermal therapy capabilities. In this study, a desolvation and cross-linking approach was employed to successfully encapsulate gold nanorods into HSAPs simultaneously with the chemotherapeutic drug paclitaxel (PAC); forming PAC-AuNR-HSAPs with desirable overall particle sizes of 299 ± 6 nm. The loading efficiency of paclitaxel into PAC-AuNR-HSAPs reached up to 3 μg PAC/mg HSA. The PAC-AuNR-HSAPs experienced photothermal heating; with the bulk particle solution reaching up to 46 °C after 15 min of near-IR laser exposure. This heat increase marked the successful attainment of the temperature necessary to cause severe cellular hyperthermia and necrosis. The encasement strategy facilitated a colloidal hybrid treatment system capable of enhanced permeability and retention effects, photothermal ablation of cancer cells, and release of the active paclitaxel of up to 188 ng (from PAC-AuNR-HSAPs created with 30 mg HSA) in a single 15 min irradiation session. When treated with PAC-AuNR-HSAPs containing 20 μg PAC/mL particle solution, 4T1 mouse breast cancer cells experienced ∼82% cell death without irradiation and ∼94% cell death after just one irradiation session. The results for PAC-AuNR-HSAPs were better than that of free PAC, which only killed ∼77% of the cells without irradiation and ∼80% with irradiation. The hybrid particle system also lends itself to future customizable external functionalities via conjugated targeting ligands, such as antibodies. Internal entrapment of patient tailored medication combinations are also possible with this combination treatment platform, which may result in improved quality of life for those undergoing treatment.

Incomplete radiofrequency ablation enhances invasiveness and metastasis of residual cancer of hepatocellular carcinoma cell HCCLM3 via activating β-catenin signaling

BACKGROUND

Radiofrequency ablation (RFA) is one of the curative therapies for hepatocellular carcinoma (HCC), however, accelerated progression of residual HCC after incomplete RFA has been reported more frequently. The underlying molecular mechanism of this phenomenon remains to be elucidated. In this study, we used an incomplete RFA orthotopic HCC nude mouse model to study the invasive and metastatic potential of residual cancer as well as the correlated mechanism.

METHODS

The incomplete RFA orthotopic nude mouse models were established using high metastatic potential HCC cell line HCCLM3 and low metastatic potential HCC cell line HepG2, respectively. The changes in cellular morphology, motility, metastasis and epithelial-mesenchymal transition (EMT), and HCC cell molecular markers after in vitro and in vivo incomplete RFA intervention were observed.

RESULTS

Pulmonary and intraperitoneal metastasis were observed in an in vivo study. The underlying pro-invasive mechanism of incomplete RFA appeared to be associated with promoting EMT, including down-regulation of E-cadherin and up-regulation of N-cadherin and vimentin. These results were in accordance with the in vitro response of HCC cells to heat intervention. Further studies demonstrated that β-catenin was a pivotal factor during this course and blocking β-catenin reduced metastasis and EMT phenotype changes in heat-treated HCCLM3 cells in vitro.

CONCLUSION

Incomplete RFA enhanced the invasive and metastatic potential of residual cancer, accompanying with EMT-like phenotype changes by activating β-catenin signaling in HCCLM3 cells.

Tumour eradication using synchronous thermal ablation and Hsp90 chemotherapy with protein engineered triblock biopolymer-geldanamycin conjugates

PURPOSE

Hepatocellular carcinoma (HCC) suffers high tumour recurrence rate after thermal ablation. Heat shock protein 90 (Hsp90) induced post-ablation is critical for tumour survival and progression. A combination therapy of thermal ablation and polymer conjugated Hsp90 chemotherapy was designed and evaluated for complete tumour eradication of HCC.

MATERIALS AND METHODS

A thermo-responsive, elastin-like polypeptide (ELP)-based tri-block biopolymer was developed and conjugated with a potent Hsp90 inhibitor, geldanamycin (GA). The anti-cancer efficacy of conjugates was evaluated in HCC cell cultures with and without hyperthermia (43 °C). The conjugates were also administered twice weekly in a murine HCC model as a single treatment or in combination with single electrocautery as the ablation method.

RESULTS

ELP-GA conjugates displayed enhanced cytotoxicity in vitro and effective heat shock inhibition under hyperthermia. The conjugates alone significantly slowed the tumour growth without systemic toxicity. Four doses of thermo-responsive ELP-GA conjugates with concomitant simple electrocautery accomplished significant Hsp90 inhibition and sustained tumour suppression.

CONCLUSION

Hsp90 inhibition plays a key role in preventing the recurrence of HCC, and the combination of ablation with targeted therapy holds great potential to improve prognosis and survival of HCC patients.