Chemoablation in Urothelial Carcinoma: A Systematic Review and Future Perspectives.

Chemoablation is an emerging treatment for urothelial carcinomas. This review provides an overview of the evidence for intracavitary chemoablation in the treatment of urothelial carcinomas. The benefits of such agents include a reduction in morbidity and diseased organ preservation. While numerous agents have shown promise, research is limited due to small patient cohorts, varying follow-up, and no standardized methodology to assess response. Therefore, to date, chemoablation has not been widely adopted. This may change as a novel mitomycin formulation has recently been approved for treating low-grade upper tract urothelial carcinoma. Future studies are ongoing which evaluate other promising chemoablation options in urothelial carcinoma.

Apaziquone for Nonmuscle Invasive Bladder Cancer: Where Are We Now?

Apaziquone is an interesting drug for intravesical use in patients with nonmuscle invasive bladder cancer; however, more research is needed to prove its actual benefit. Although the apaziquone trials demonstrate the potential of this new drug, the singular phase 3 trials did not reach their primary endpoint. To date, no new trials are recruiting, so the development of apaziquone seems to have stopped.

Inactivation of apaziquone by haematuria: implications for the design of phase III clinical trials against non-muscle invasive bladder cancer.

PURPOSE: Despite positive responses in phase II clinical trials, the bioreductive prodrug apaziquone failed to achieve statistically significant activity in non-muscle invasive bladder cancer in phase III trials. Apaziquone was administered shortly after transurethral resection and here we test the hypothesis that haematuria inactivates apaziquone. METHODS: HPLC analysis was used to determine the ability of human whole blood to metabolise apaziquone ex vivo. An in vitro model of haematuria was developed and the response of RT112 and EJ138 cells following a 1-h exposure to apaziquone was determined in the presence of urine plus or minus whole blood or lysed whole blood. RESULTS: HPLC analysis demonstrated that apaziquone is metabolised by human whole blood with a half-life of 78.6 ± 23.0 min. As a model for haematuria, incubation of cells in media containing up to 75% buffered (pH 7.4) urine and 25% whole blood was not toxic to cells for a 1-h exposure period. Whole blood (5% v/v) significantly (p < 0.01) reduced the potency of apaziquone in this experimental model. Lysed whole blood also significantly (p < 0.05) reduced cell growth, although higher concentrations were required to achieve an effect (15% v/v). CONCLUSIONS: The results of this study demonstrate that haematuria can reduce the potency of apaziquone in this experimental model. These findings impact upon the design of further phase III clinical trials and strongly suggest that apaziquone should not be administered immediately after transurethral resection of non-muscle invasive bladder cancer when haematuria is common.

Effect of combining glucocorticoids with Compound A on glucocorticoid receptor responsiveness in lymphoid malignancies.

Glucocorticoids (GCs) are a cornerstone in the treatment of lymphoid malignancies such as multiple myeloma (MM) and acute lymphoblastic leukemia (ALL). Yet, prolonged GC use is hampered by deleterious GC-related side effects and the emergence of GC resistance. To tackle and overcome these GC-related problems, the applicability of selective glucocorticoid receptor agonists and modulators was studied, in search of fewer side-effects and at least equal therapeutic efficacy as classic GCs. Compound A (CpdA) is a prototypical example of such a selective glucocorticoid receptor modulator and does not support GR-mediated transactivation. Here, we examined whether the combination of CpdA with the classic GC dexamethasone (Dex) may improve GC responsiveness of MM and ALL cell lines. We find that the combination of Dex and CpdA does not substantially enhance GC-mediated cell killing. In line, several apoptosis hallmarks, such as caspase 3/7 activity, PARP cleavage and the levels of cleaved-caspase 3 remain unchanged upon combining Dex with CpdA. Moreover, we monitor no additional inhibition of cell proliferation and the homologous downregulation of GR is not counteracted by the combination of Dex and CpdA. In addition, CpdA is unable to modulate Dex-liganded GR transactivation and transrepression, yet, Dex-mediated transrepression is also aberrant in these lymphoid cell lines. Together, transrepression-favoring compounds, alone or combined with GCs, do not seem a valid strategy in the treatment of lymphoid malignancies.

Targeting the NRF-2/RHOA/ROCK signaling pathway with a novel aziridonin, YD0514, to suppress breast cancer progression and lung metastasis.

Metastasis is a major cause of breast cancer-associated mortality. Natural products extracted from herbs provide rich bioactive compounds with anticancer efficacy but may have limited or moderate potency and considerable toxicity. We developed a novel aziridonin, YD0514, by aziridinating oridonin, a natural product of the medicinal herb Rabdosia rubescens. In this study, we found that YD0514 significantly inhibited proliferation, motility, and adhesion of metastatic breast cancer cell lines MDA-MB-231, GI101, GILM2, and GILM3. YD0514 also decreased the protein expression of matrix metalloproteinases 2 and 9 (MMP2 and MMP9), focal adhesion kinase (FAK), and integrin family members. Importantly, YD0514 suppressed the growth of metastatic breast cancer xenograft tumors and significantly inhibited lung metastasis in vivo. Lastly, we showed that YD0514's anti-metastatic effect on highly aggressive breast cancer is mediated via regulating the NRF-2/RHOA/ROCK signaling pathway. These results demonstrate that YD0514, the first active analog based on an oridonin D-ring modification, has the potential to be developed as an anti-metastasis therapy for patients with metastatic cancers.

The efficacy of Apaziquone in the treatment of bladder cancer.

INTRODUCTION: Bladder cancer is nowadays a common tumor. Non-muscle invasive bladder cancer (NMIBC) has still chances of recurrence and progression in spite of surgery and adjuvant treatments. New therapies are being developed to reduce these percentages with less adverse effects - Apaziquone (EO9) is an example. Areas covered: A literature search has been performed using Pubmed, UpToDate and Google verified information (mainly from Food and Drug Administration and Spectrum Pharmaceutics websites). We have included data from the most representative clinical trials and reviews published. Expert opinion: Apaziquone is considered a promising chemical agent if applied intravesically due mainly to its pharmacodynamics and safety profile. There is evidence for this with respect to adjuvant chemo ablative therapy and as a post-transurethral resection of bladder (TURB) single-dose regimen. As a result, new clinical phase III trials are needed both to evaluate its efficacy as an adjuvant therapy in the spectrum from intermediate- to high-risk non-muscle invasive bladder cancer and to select the most appropriate candidates and treatment schedule. As a conclusion, Apaziquone is a good candidate to become a better alternative as an adjuvant therapy for the treatment of NMIBC in the near future.

Efficacy, pharmacokinetic and pharmacodynamic evaluation of apaziquone in the treatment of non-muscle invasive bladder cancer.

INTRODUCTION: Apaziquone (also known as EO9 and QapzolaTM) is a prodrug that is activated to DNA damaging species by oxidoreductases (particularly NQO1) and has the ability to kill aerobic and/or hypoxic cancer cells. Areas covered: Whilst its poor pharmacokinetic properties contributed to its failure in phase II clinical trials when administered intravenously, these properties were ideal for loco-regional therapies. Apaziquone demonstrated good anti-cancer activity against non-muscle invasive bladder cancer (NMIBC) when administered intravesically to marker lesions and was well tolerated with no systemic side effects. However, phase III clinical trials did not reach statistical significance for the primary endpoint of 2-year recurrence in apaziquone over placebo although improvements were observed. Post-hoc analysis of the combined study data did indicate a significant benefit for patients treated with apaziquone, especially when the instillation of apaziquone was given 30 min or more after surgery. A further phase III study is ongoing to test the hypotheses generated in the unsuccessful phase III studies conducted to date. Expert opinion: Because of its specific pharmacological properties, Apaziquone is excellently suited for local therapy such as NMIBC. Future studies should include proper biomarkers.

Activation of multiple chemotherapeutic prodrugs by the natural enzymolome of tumour-localised probiotic bacteria.

Some chemotherapeutic drugs (prodrugs) require activation by an enzyme for efficacy. We and others have demonstrated the ability of probiotic bacteria to grow specifically within solid tumours following systemic administration, and we hypothesised that the natural enzymatic activity of these tumour-localised bacteria may be suitable for activation of certain such chemotherapeutic drugs. Several wild-type probiotic bacteria; Escherichia coli Nissle, Bifidobacterium breve, Lactococcus lactis and Lactobacillus species, were screened against a panel of popular prodrugs. All strains were capable of activating at least one prodrug. E. coli Nissle 1917 was selected for further studies because of its ability to activate numerous prodrugs and its resistance to prodrug toxicity. HPLC data confirmed biochemical transformation of prodrugs to their toxic counterparts. Further analysis demonstrated that different enzymes can complement prodrug activation, while simultaneous activation of multiple prodrugs (CB1954, 5-FC, AQ4N and Fludarabine phosphate) by E. coli was confirmed, resulting in significant efficacy improvement. Experiments in mice harbouring murine tumours validated in vitro findings, with significant reduction in tumour growth and increase in survival of mice treated with probiotic bacteria and a combination of prodrugs. These findings demonstrate the ability of probiotic bacteria, without the requirement for genetic modification, to enable high-level activation of multiple prodrugs specifically at the site of action.

Quantitative proteomic analysis of anticancer drug RH1 resistance in liver carcinoma.

Acquired resistance of tumor cells to the therapeutic treatment is a major challenge in virtually any chemotherapy. A novel anticancer agent 2,5-diaziridinyl-3-(hydroxymethyl)-6-methyl-1,4-benzoquinone (RH1) is designed to be activated by NAD(P)H: quinone oxidoreductase, an enzyme expressed at high levels in many types of tumors. Here we investigated the potential mechanisms of acquired RH1 drug resistance in cancer cells by applying high-throughput differential quantitative proteomic analysis of the newly established RH1-resistant hepatoma cell lines. Over 400 proteins display significantly altered levels between drug-sensitive and drug-resistant cell lines. Differentially expressed proteins were clustered into more than 14 groups according to their functional annotation and protein-protein interactions. Bioinformatic analysis highlights the biological processes that might be responsible for acquired resistance to RH1. The level of several xenobiotic metabolism enzymes (total n=17) involved in RH1 activation and detoxification is decreased (Nqo1, catalase, Gst, Gsr), corresponding with the decrease in their catalytic activity. The altered biological processes also include the decrease of cell cycle positive regulators (n=15) and the increase of DNA repair proteins (n=5) as well as annexin family members (n=5) in the RH1-resistant cells. Drug-resistant hepatoma cell proteomes are also distinguished by the altered level of proteins involved in energy production and metabolism (n=55). Our data provide the basis for in-depth study of molecular mechanisms of tumor cell resistance to the promising anticancer drug RH1 enabling the further validation of protein biomarkers for the drug insusceptibility and of potential secondary pharmacological targets of RH1 resistant cells.

Folate-conjugated chitosan-poly(ethylenimine) copolymer as an efficient and safe vector for gene delivery in cancer cells.

Folic acid (FA) has high affinity to folate receptors (FRs), which have three isoforms: FRα, FRß and FRγ. Among them, FRα is a tumor specific receptor, as it is frequently over-expressed in diverse malignancies but not in normal tissues. In this study, we have conjugated FA to a chitosan-poly(ethylenimine) copolymer, and have confirmed the low cytotoxicity of the product (namely "CP1.3K-FA") in cancer cells. The transfection efficiency of CP1.3K-FA has been shown by the EGFP transfection assay to be higher than that of the unmodified chitosan-poly(ethylenimine) copolymer under optimal conditions. Results of the luciferase activity assay have also indicated that the transfection efficiency of CP1.3K-FA is comparable to that of Fugene HD in B16 and U87 cells. Our results have suggested that CP1.3K-FA warrants further development as a vector for gene delivery in cancer cells.

Anticancer Activity of Apaziquone in Oral Cancer Cells and Xenograft Model: Implications for Oral Cancer Therapy.

Oral squamous cell carcinoma (OSCC) patients diagnosed in late stages have limited chemotherapeutic options underscoring the great need for development of new anticancer agents for more effective disease management. We aimed to investigate the anticancer potential of Apaziquone, [EOquin, USAN, E09, 3-hydroxy-5- aziridinyl-1-methyl-2(1H-indole-4,7-dione)-prop-ß-en-α-ol], a pro-drug belonging to a class of anti-cancer agents called bioreductive alkylating agents, for OSCC. Apaziquone treatment inhibited cell proliferation and induced apoptosis in OSCC cells in vitro. Apaziquone treated OSCC cells showed increased activation of Caspase 9 and Caspase 3, and Poly (ADP ribose) polymerase (PARP) cleavage suggesting induction of apoptosis by apaziquone in oral cancer cells. Importantly, apaziquone treatment significantly reduced oral tumor xenograft volume in immunocompromised NOD/SCID/Crl mice without causing apparent toxicity to normal tissues. In conclusion, our in vitro and in vivo studies identified and demonstrated the pre-clinical efficacy of Apaziquone, as a potential novel anti-cancer therapeutic candidate for oral cancer management.

Development and characterization of sulfasalazine loaded fucosylated PPI dendrimer for the treatment of cytokine-induced liver damage.

The present investigation was aimed at exploring the targeting potential of sulfasalazine (NF-κB inhibitor drug) loaded fucose tethered poly (propylene imine) (PPI) dendritic nanoarchitecture (SSZ-FUCO-PPID) to Kupffer cells for effective management of cytokine-induced liver damage. The SSZ-FUCO-PPID formulation was characterized for entrapment efficiency, in vitro release, stability, toxicological investigations, macrophage uptake, NF-κB inhibition, and in vivo studies. In cell uptake assay the uptake of SSZ-FUCO-PPID was found to be higher and preferentially by J774 macrophage cell line. Cytokine assay suggested that the SSZ-FUCO-PPID potentially inhibited the IL-12 p40 production in LPS activated macrophages. Western blot analysis clearly suggested that SSZ-FUCO-PPID inhibited the activation of NF-κB as indicated by the absence of p-IκB band. Pharmacokinetic study revealed improved bioavailability, half-life and mean residence time of SSZ upon fucosylation of dendrimers. The biodistribution pattern clearly established the higher amount of SSZ-FUCO-PPID in liver. Hematological data suggest that the fucosylated formulations are less immunogenic as compared to unconjugated formulations. The results suggest that the SSZ-FUCO-PPID formulation holds targeting potential to Kupffer cells for the treatment of cytokine-induced liver damage.

Dual-therapeutic reporter genes fusion for enhanced cancer gene therapy and imaging.

Two of the successful gene-directed enzyme prodrug therapies include herpes simplex virus-thymidine kinase (HSV1-TK) enzyme-ganciclovir prodrug and the Escherichia coli nitroreductase (NTR) enzyme-CB1954 prodrug strategies; these enzyme-prodrug combinations produce activated cytotoxic metabolites of the prodrugs capable of tumor cell death by inhibiting DNA synthesis and killing quiescent cells, respectively. Both these strategies also affect significant bystander cell killing of neighboring tumor cells that do not express these enzymes. We have developed a dual-combination gene strategy, where we identified HSV1-TK and NTR fused in a particular orientation can effectively kill tumor cells when the tumor cells are treated with a fusion HSV1-TK-NTR gene- along with a prodrug combination of GCV and CB1954. In order to determine whether the dual-system demonstrate superior therapeutic efficacy than either HSV1-TK or NTR systems alone, we conducted both in vitro and in vivo tumor xenograft studies using triple negative SUM159 breast cancer cells, by evaluating the efficacy of cell death by apoptosis and necrosis upon treatment with the dual HSV1-TK genes-GCV-CB1954 prodrugs system, and compared the efficiency to HSV1-TK-GCV and NTR-CB1954. Our cell-based studies, tumor regression studies in xenograft mice, histological analyses of treated tumors and bystander studies indicate that the dual HSV1-TK-NTR-prodrug system is two times more efficient even with half the doses of both prodrugs than the respective single gene-prodrug system, as evidenced by enhanced apoptosis and necrosis of tumor cells in vitro in culture and xenograft of tumor tissues in animals.

Phase 2 study of adjuvant intravesical instillations of apaziquone for high risk nonmuscle invasive bladder cancer.

PURPOSE: We studied the safety and efficacy of multiple adjuvant apaziquone instillations in patients with high risk nonmuscle invasive bladder cancer. MATERIALS AND METHODS: Patients with high risk nonmuscle invasive urothelial carcinoma of the bladder underwent transurethral resection of all bladder tumor(s), and received 6 weekly adjuvant intravesical apaziquone instillations of 4 mg in 40 ml. Patients with carcinoma in situ received 3 further maintenance instillations at months 3, 6 and 12. Followup consisted of cystoscopy, urine cytology and observation of adverse events every 3 months for 18 months. RESULTS: A total of 53 patients were enrolled in the study. Although all patients were high risk according to the definitions used when the study was initiated, according to most recent guideline criteria, 80% and 20% of these patients would now be considered intermediate and high risk for recurrence, and 50% and 44% would be considered intermediate and high risk for progression, respectively. Intent to treat analysis of 49 patients with papillary tumors showed recurrent tumors in 34.7% and 44.9% at 12 and 18 months, respectively. One patient had progression to T2 or greater urothelial carcinoma after 9 months. There were 4 patients with carcinoma in situ who had complete responses at 3 months but discontinued treatment due to cystitis, recurrent papillary disease, urinary incontinence and dysuria. Most other side effects were mild (grade 1 to 2). CONCLUSIONS: Adjuvant intravesical instillations of apaziquone are generally well tolerated. The recurrence rates of 34.7% after 12 months and 44.9% after 18 months in these patients can be considered encouraging, and warrant further study.

Apaziquone as an intravesical therapeutic agent for urothelial non-muscle-invasive bladder cancer.

INTRODUCTION: Urothelial carcinoma of the bladder is a disease prone to recurrence. A new cytotoxic drug, apaziquone, is an analog of mitomycin C. Given via intravesical instillations it has the ability to specifically target cancer cells. AREAS COVERED: This article reviews the discovery and pharmacological properties of the agent and the first steps of its application in human disease. The poor performance of the drug as a systemic medication is discussed along with in vivo and in vitro studies that have led to current intravesical applications with encouraging results. In detail the limited number of clinical studies on the drug and compare them with relevant series on currently used agents. In addition, different strategies to enhance the efficacy of other agents are discussed and possible application of this experience to apaziquone is proposed. EXPERT OPINION: Apaziquone is a promising local agent for the treatment and prevention of recurrent urothelial carcinoma of the bladder. The limited number of Phase II studies has demonstrated potency and relatively low toxicity. In light of the dearth of randomized controlled trials, Phase III studies are urgently needed before any conclusive pronouncements on this agent can be made.

Increases in serotonergic neuronal activity following intracerebroventricular administration of AF64A in rats.

Changes in the serotonergic nervous system after the intracerebroventricular (i.c.v.) administration of ethylcholine aziridinium (AF64A, 3 nmol/each ventricle) were studied in rats. Two weeks after the infusion of AF64A, the levels of 5-HT and 5-HIAA in microdialysed cerebrospinal fluid (CSF), the levels of total 5-HT and 5-HIAA, the density of serotonin uptake sites and the activities of tryptophan hydroxylase (TPH) and monoamine oxidase (MAO) in various brain regions were determined. After AF64A administration, the concentrations of 5-HT in lateral ventricle were increased and the levels of 5-HIAA were decreased. However, the hippocampal levels of total 5-HT were decreased without changes in the levels of 5-HIAA and the hippocampal turnover rates of 5-HT increased. Also, the density of uptake sites of serotonin ([(3)H]citalopram binding sites) was decreased in the various brain. The activities of TPH were increased in striatum and frontal cortex and the activity of MAO was also increased in striatum. These results indicate that AF64A induces an increase in serotonergic neuronal activity and decreased densities of 5-HT uptake sites which may affect the change in the other parameters of serotonergic neuronal activities. Furthermore, these results suggest that the impaired cholinergic neuronal activity induces the alteration in the serotonergic nervous activities.

Nicotine improves AF64A-induced spatial memory deficits in Morris water maze in rats.

Ethylcholine mustard aziridinium ion (AF64A) is a neurotoxic derivative of choline that produces not only long-term presynaptic cholinergic deficits, but also various memory deficits in rats similar to some characteristics observed in Alzheimer's disease patients. This study investigated whether nicotine (NCT) administration attenuated spatial learning deficits induced by intracerebroventricular AF64A treatment. AF64A (6 nmol/6 microl)-or saline (SAL)-treated rats were trained in Morris water maze task. NCT (0.025-0.25mg/kg) was subcutaneously injected 5 min before the training every day. The results showed that moderate dose (0.10mg/kg) of NCT attenuated AF64A-induced prolongation of escape latency. Furthermore, NCT dose-dependently recovered the AF64A-induced decrease of time spent in the target quadrant in the probe test. These results suggest that NCT improves AF64A-induced spatial memory deficits, and thus it is a potential therapeutic agent for the treatment of memory deficits in dementia.

Preclinical efficacy of the bioreductive alkylating agent RH1 against paediatric tumours.

BACKGROUND: Despite substantial improvements in childhood cancer survival, drug resistance remains problematic for several paediatric tumour types. The urgent need to access novel agents to treat drug-resistant disease should be expedited by pre-clinical evaluation of paediatric tumour models during the early stages of drug development in adult cancer patients. METHODS/RESULTS: The novel cytotoxic RH1 (2,5-diaziridinyl-3-[hydroxymethyl]-6-methyl-1,4-benzoquinone) is activated by the obligate two-electron reductase DT-diaphorase (DTD, widely expressed in adult tumour cells) to a potent DNA interstrand cross-linker. In acute viability assays against neuroblastoma, osteosarcoma, and Ewing's sarcoma cell lines RH1 IC(50) values ranged from 1-200 nM and drug potency correlated both with DTD levels and drug-induced apoptosis. However, synergy between RH1 and cisplatin or doxorubicin was only seen in low DTD expressing cell lines. In clonogenic assays RH1 IC(50) values ranged from 1.5-7.5 nM and drug potency did not correlate with DTD level. In A673 Ewing's sarcoma and 791T osteosarcoma tumour xenografts in mice RH1 induced apoptosis 24 h after a single bolus injection (0.4 mg/kg) and daily dosing for 5 days delayed tumour growth relative to control. CONCLUSION: The demonstration of RH1 efficacy against paediatric tumour cell lines, which was performed concurrently with the adult Phase 1 Trial, suggests that this agent may have clinical usefulness in childhood cancer.

A new in vitro model for stem cell differentiation and interaction.

Development involves an interplay between various cell types from their birth to their disappearance by differentiation, migration, or death. Analyzing these interactions provides insights into their roles during the formation of a new organism. As a study tool for these interactions, we have created a model based on embryoid bodies (EBs) generated from mouse embryonic stem (mES) cells, which can be used to visualize the differentiation of mES cells into specific cell types while at the same time allowing controlled removal of this same cell population using an enzyme-prodrug approach. Cell-specific expression of Cre induces a switch of EGFP expression to LacZ. Furthermore, it leads to the expression of nitroreductase (NTR), which in combination with the prodrug CB1954 induces apoptosis. Here, we validate this model by showing expression of LacZ and NTR after Cre-mediated recombination. Additionally we show, as an example, that we can target the endothelial cells in EBs using the Tie-2 promoter driving Cre. Ablating Cre-expressing cells by adding CB1954 to the culture led to an abrogated vascular formation. This system can easily be adapted to determine the fate and interaction of many different cell types provided that there is a cell-type-specific promoter available.

Two-year follow-up of the phase II marker lesion study of intravesical apaziquone for patients with non-muscle invasive bladder cancer.

OBJECTIVES: To study the time-to-recurrence and duration of response in non-muscle invasive bladder cancer (NMIBC) patients, with a complete ablative response after intravesical apaziquone instillations. METHODS: Transurethral resection of bladder tumour(s) (TURBT) was performed in patients with multiple pTa-T1 G1-2 urothelial cell carcinoma (UCC) of the bladder, with the exception of one marker lesion of 0.5-1.0 cm. Intravesical apaziquone was administered at weekly intervals for six consecutive weeks, without maintenance instillations. A histological confirmed response was obtained 2-4 weeks after the last instillation. Routine follow-up (FU) was carried out at 6, 9, 12, 18 and 24 months from the first apaziquone instillation. RESULTS: At 3 months FU 31 of 46 patients (67.4%) had a complete response (CR) to ablative treatment. Side-effects on the long-term were only mild. Two CR patients dropped out during FU. On intention-to-treat (ITT) analysis 49.5% of the CR patients were recurrence-free at 24 months FU, with a median duration of response of 18 months. Of 15 no response (NR) patients, only two received additional prophylactic instillations after TURBT. On ITT-analysis 26.7% of the NR patients were recurrence-free (log rank test, P = 0.155). The overall recurrence-free survival was 39% (18 of 46 patients) at 24 months FU. CONCLUSIONS: The CR of the marker lesion in 67% of patients was followed by a recurrence-free rate of 56.5% at 1-year FU, and 49.5% at 2-year FU. These long-term results are good in comparison with the results of other ablative studies.