Electroporation in Translational Medicine: From Veterinary Experience to Human Oncology

Electroporation (EP) is a broadly accepted procedure that, through the application of electric pulses with appropriate amplitudes and waveforms, promotes the delivery of anticancer molecules in various oncology therapies. EP considerably boosts the absorptivity of targeted cells to anticancer molecules of different natures, thus upgrading their effectiveness. Its use in veterinary oncology has been widely explored, and some applications, such as electrochemotherapy (ECT), are currently approved as first-line treatments for several neoplastic conditions. Other applications include irreversible electroporation and EP-based cancer vaccines. In human oncology, EP is still mostly restricted to therapies for cutaneous tumors and the palliation of cutaneous and visceral metastases of malignant tumors. Fields where veterinary experience could help smooth the clinical transition to humans include intraoperative EP, interventional medicine and cancer vaccines. This article recapitulates the state of the art of EP in veterinary and human oncology, recounting the most relevant results to date.

Electrochemotherapy in translational medicine: from veterinary experience to human oncology

Electrochemotherapy (ECT) is a tumor treatment that, through the application of electric pulses with suitable amplitude and waveforms, favors the systemic or local delivery of chemotherapy agents. This procedure significantly increases the permeability of cancer cells to anticancer drugs, making them more effective and allowing their use at lower doses with less morbidity for patients. Its use in veterinary oncology is consolidated and it is currently adopted as first-line treatment for different cancers with successful results. In human oncology, ECT use is mainly in the treatment of cutaneous tumors and for the palliation of cutaneous metastases of malignant tumors. A standard operating procedure has been formulated. Currently, several preclinical and phase I and II studies are under way involving various cancers in humans to better define the efficacy and tolerability of this therapy. This review summarizes the state of the art of ECT in veterinary and human oncology, describing the most significant results achieved to date.

Electrochemotherapy for the treatment of cutaneous solid tumors in equids: A retrospective study

Background

Electrochemotherapy (ECT) promotes the increased uptake of antitumor agents through the administration of permeabilizing electric pulses, thus enhancing chemotherapy effectiveness.

Aim

Our study aimed to describe the tolerability and efficacy of ECT alone or in association with surgery to manage solid neoplasms in equids.

Methods

Medical records of equids with a diagnosis of malignant tumors treated with ECT alone or in combination with surgery were retrospectively evaluated. Each equid received local treatment within the tumors or the tumors' bed with cisplatin at the dose of 0.5 mg/cm². Trains of permeabilizing biphasic electric pulses were then applied under spinal or general anesthesia.

Results

Sixteen equids were enrolled in this study. There were nine melanoma cases, four fibrosarcoma, and three squamous cell carcinoma. Of those 16 equids, 7 received ECT for treatment of intraoperative local disease, while in 9 cases, ECT was the only treatment modality. The seven equids treated with the combination of ECT and surgery still have no evidence of disease at different times ranging from 9 to 60 months. The remaining nine had the following responses: two complete remissions, five partial responses, one stable disease, and one progressive disease. The treatment was well-tolerated, and local side effects were minimal. No systemic effects were documented.

Conclusion

This retrospective study suggests that ECT may be beneficial for equids with solid neoplasms and could be a useful addition to the current therapeutic options considering its low cost, limited toxicity, and ease of administration.

Evaluation of electrochemotherapy in the management of apocrine gland anal sac adenocarcinomas in dogs: A retrospective study

Background

Electrochemotherapy (ECT) combines the administration of anticancer drugs with the delivery of electric pulses, thus increasing the drug uptake through the cell membranes, resulting in increased efficacy.

Aim

The aim of our study was to describe the tolerability and efficacy of ECT alone or in association with other treatment modalities for the management of apocrine gland anal sac adenocarcinoma (AGASAC).

Methods

Medical records of dogs with a diagnosis of AGASAC that were treated with ECT alone or in combination with surgery/chemotherapy were retrospectively evaluated. Each dog received 20 mg/m² of bleomycin intravenously. Based on the clinician's decision, the primary tumor or tumor bed was also infiltrated with cisplatin at the dose of 0.5 mg/cm². Trains of permeabilizing biphasic electric pulses were then applied under general anesthesia.

Results

Ten dogs were enrolled in the study. Of those 10 dogs, only one received ECT for treatment of microscopic local disease, while in six cases ECT was the only treatment modality. In three dogs, ECT was followed by systemic medical treatment. Six dogs (60%) had a partial response (PR), three dogs (30%) had stable disease, and one dog treated for microscopic disease did not show any sign of local relapse for 305 days after treatment, being still alive and in complete remission at the time of writing this article. The median time to progression was 303 days and the median survival time was 365 days. The treatment was well tolerated and local side effects were minimal. No systemic effects were documented.

Conclusion

This preliminary study suggests that ECT may be beneficial for dogs with AGASAC and could be a useful addition to the current therapeutic options in consideration of its low cost, limited toxicity, and ease of administration.

Comparison of two different doses of bleomycin in electrochemotherapy protocols for feline cutaneous squamous cell carcinoma nonsegregated from ultraviolet light exposure

Cutaneous squamous cell carcinoma (cSCC) is one of the most common skin tumors in cats due to chronic exposure to ultraviolet light. Local treatments such as electrochemotherapy (ECT) promote disease control or even complete remission. We hypothesize that cats could benefit from treatments using bleomycin at reduced dosages. A prospective nonrandomized single-blind study evaluated the clinical parameters, site lesion, staging, disease-free interval (DFI) and survival time by comparing the standard dose of bleomycin (15,000 UI/m2) (n = 22) with a reduced dose (10,000 UI/m2) (n = 34) in cats with cSCC that underwent ECT as the sole treatment modality. No statistically significant difference in DFI or overall survival was observed between the 2 groups. A higher DFI was found in cats with a small tumor size (less than 0.33 cm3) compared with that for cats with a large tumor size (P = 0.045). Furthermore, a reduced overall survival time for cats with a higher stage in the standard group SG (T3 and T4) (P = 0.004) was observed when compared to that for cats with a lower stage (T1 and T2). In conclusion, ECT using both doses of bleomycin may achieve the same response rate in terms of the overall response, DFI, and overall survival.

Combination of bleomycin and cisplatin as adjuvant electrochemotherapy protocol for the treatment of incompletely excised feline injection-site sarcomas: A retrospective study

Background

fFeline injection-site sarcomas (FISSs) are mesenchymal tumors that can occur in cats after injections of different medical agents and are easily prone to recurrence.

Aim

The aims of this study were to report treatment outcomes for cats with feline injection-site sarcomas (FISSs) treated with both bleomycin and cisplatin, per adjuvant electrochemotherapy (ECT) protocol.

Methods

The medical records of cats with a diagnosis of FISS that were treated with ECT using both bleomycin and cisplatin were retrospectively evaluated. A total of 27 cats were available for statistical evaluation of their response. The cats received intravenous 20 mg/m2 bleomycin, and the tumor bed and margins were infiltrated with cisplatin at the dose of 0.5 mg/cm2. Then, the trains of permeabilizing biphasic electric pulses lasting 50 + 50 µseconds each were delivered in bursts of 1,300 V/cm using caliper electrodes under sedation. A second session was performed 2 weeks later.

Results

Side effects were limited to local inflammation in three cats. Three cats developed local tumor recurrence at days 180, 180, and 545 after surgery, two cats developed recurrence and metastases at 100 and 505 days after surgery, and two cats experienced distant metastases. A median time to recurrence could not be calculated as over 80% of the study population remained disease free or were censored due to death from other causes. Mean survival time was 985 days, and median cumulative survival for all cases was 1,000 days.

Conclusion

When compared to historical controls, the results of this study demonstrate the superior rates of tumor-free survival and disease-free interval. This adjuvant therapy could be a useful addition to the current options for FISS in consideration of its efficacy, limited toxicity, and ease of administration.

Adjuvant electrochemotherapy with bleomycin and cisplatin combination for canine soft tissue sarcomas: A study of 30 cases

Electrochemotherapy (ECT) couples the administration of anticancer drugs with the delivery of electric pulses that increase the drug uptake through the cell membranes, thus resulting in an improved efficacy. This study has evaluated the tolerability and efficacy of the combination of systemic bleomycin and local cisplatin as ECT agents for incompletely excised canine soft tissue sarcoma (STS). Thirty dogs with incompletely excised STSs were enrolled. The dogs received intravenous 20 mg/m² bleomycin, and the tumor bed and margins were infiltrated with cisplatin at the dose of 0.5 mg/cm². Then, trains of permeabilizing biphasic electric pulses were applied under sedation. More precisely, 5 min after the injection of the chemotherapy agents, sequences of eight biphasic pulses lasting 50 + 50 μsec each, were delivered in bursts of 1,300 V/cm using caliper electrodes. A second session was performed 2 wk later. The treatment was well tolerated and side effects were minimal. Twenty-six dogs had no evidence of recurrence at the time of manuscript writing; four had recurrence and one of the four recurring dogs died of lung metastases. Median estimated disease free was 857 d. Perivascular wall tumors response was compared to that of the other STSs, but the difference in outcome was not significant. ECT using combination of bleomycin and cisplatin appears to be effective in the treatment of incompletely resected STSs in dogs. This therapeutic approach could be a useful addition to the current options in consideration of its low cost, limited toxicity, and ease of administration.

Successful Treatment of a Keratoacanthoma with Electrochemotherapy: A Case Report

Introduction

Few studies have evaluated the efficacy of intralesional bleomycin injection combined with electroporation for the treatment of cutaneous tumors. However, the phenomenon that electroporation can enhance the cytotoxicity of bleomycin in vivo by 300–700 fold has been intensely investigated.

Case Presentation

Keratoacanthoma in an 86-year-old patient was treated with intralesional bleomycin combined with electroporation. Treatment consisted of local application of shorty and intense electric pulses followed by local injection of bleomycin. Electroporation was always well tolerated by the patient, with no significant complaints, and the tumor had completely regressed by day 71 of the follow-up.

Conclusion

The results suggest that intralesional bleomycin injection combined with electroporation could represent a valid alternative therapeutic approach for the treatment of keratoacanthomas.

Successful treatment of plantar warts with intralesional bleomycin and electroporation: pilot prospective study

BACKGROUND

Numerous studies have been performed to evaluate the efficacy of intralesional bleomycin for the treatment of warts with inconsistent result. Nevertheless, it is well known that the cytotoxicity of bleomycin can be enhanced in vivo by 300 to 700-fold by electroporation.

OBJECTIVE AND METHODS

In this article, we present an interventional, one-center, prospective case series, clinical trial of the effectiveness of intralesional bleomycin combined with electroporation for the treatment of plantar warts, in comparison to the use of intralesional bleomycin alone.

RESULTS

The study's cohort included 12 men and 10 women, with a mean age of 53.8 years. A total of 22 warts were treated. In dividing the patients in two groups (complete remission against all the others) and analyzing the different outcomes in the two arms of patients, a statistical significant difference was found (p=0.0015), proving a greater efficacy of the treatment with bleomycin combined with ECT as opposed to bleomycin alone. Electroporation was always well tolerated by the patients with no discomfort.

CONCLUSIONS

This study serves as a basis for the application of novel protocols in the treatment of different benign and locally malignant skin lesion by means of electroporation.

Surgery and electrochemotherapy treatment of incompletely excised mammary carcinoma in two male pet rats (Rattus norvegicus)

Two male rats (Rattus norvegicus; 18 and 24 months old), were referred for treatment of large masses located in the axillary area. Following total body radiography and hematological and serum biochemical analysis, the rats were anesthetized, and the masses were surgically removed. Both lesions were diagnosed as mammary carcinoma based on histopathological diagnosis. The tumor beds were treated with two sessions of electrochemotherapy (ECT), two weeks apart. ECT involved cisplatin administration in the tumor bed, followed by a series of eight biphasic electric pulses. The treatment was well tolerated, and the rats were disease-free after 10 and 14 months. Therefore, adjuvant ECT resulted in good local control of mammary carcinoma and can potentially be used for adjuvant treatment of pet rats with cutaneous and adnexal tumors.

Electrochemotherapy increases local control after incomplete excision of a recurring penile fibrosarcoma in a stallion

An eleven-year-old stallion was referred for adjuvant treatment of an incompletely excised, recurring penile fibrosarcoma. The horse was bright, alert and responsive with a 15 x 12 cm ulcerated lesion on the ventral side of the penis. The lesion was the tumor bed of an incompletely excised fibrosarcoma. After complete staging procedures, the owner elected to treat the horse with electrochemotherapy (ECT) using cisplatin as chemotherapy agent. Two sessions of ECT were performed at two-week intervals using local cisplatin followed by trains of biphasic electric pulses applied using different electrodes until complete coverage of the area was achieved. The treatment was well tolerated, and the patient is still disease free after 12 months. ECT resulted in improved local control and should be considered among the available adjuvant treatments in equines carrying soft tissue tumors.

Novel Instruments for the Implementation of Electrochemotherapy Protocols: From Bench Side to Veterinary Clinic

Electrochemotherapy (ECT) is a medical strategy that allows an increased efficacy of chemotherapy agents after the application of permeabilizing electric pulses having appropriate characteristics (form, voltage, frequency). In the past 10 years, the clinical efficacy of this therapeutic approach in several spontaneous models of tumors in animals has been shown. Moreover, some of the molecular and cellular mechanisms responsible for this phenomenon have been elucidated. Our group has been deeply involved in the development of new ECT protocols for companion animals, implementing the use of the technique as first line treatment, and evaluating different chemotherapy agents in laboratory animals as well as pets. This article summarizes the most important advances in veterinary ECT, including the development of novel equipment, therapeutic protocols, and their translation to humans. J. Cell. Physiol. 232: 490-495, 2017. © 2016 Wiley Periodicals, Inc.

Electrochemotherapy as First Line Cancer Treatment: Experiences from Veterinary Medicine in Developing Novel Protocols

Tumor microenvironment is one of the major obstacles to the efficacy of chemotherapy in cancer patients. The abnormal blood flow within the tumor results in uneven drug distribution. Electrochemotherapy (ECT) is a tumor treatment that adopts the systemic or local delivery of anticancer drugs with the application of permeabilizing electric pulses having appropriate amplitude and waveforms. This allows the use of lipophobic drugs that frequently have a narrow therapeutic index maintaining at the same time a reduced patient morbidity and preserving appropriate anticancer efficacy. Its use in humans is addressed to the treatment of cutaneous neoplasms or the palliation of skin tumor metastases, and a standard operating procedure has been devised. On the other hand, in veterinary oncology this approach is gaining popularity, thus becoming a first line treatment for different cancer histotypes, in a variety of clinical conditions due to its high efficacy and low toxicity. This review summarizes the state of the art in veterinary oncology as a preclinical model and reports the new protocols in terms of drugs and therapy combination that have been developed.

Dietary Protective Effects Against Hepatocellular Carcinoma Development in Mdr2-/- Knockout Mice

BACKGROUND/AIM

The Mdr2(-/-) mouse develops early chronic cholestatic hepatitis and hepatocellularcarcinoma (HCC) when adult. We tested the effects of a restricted-calorie diet on HCC development in Mdr2(-/-) mice.

MATERIALS AND METHODS

Mdr2(-/-) mice (n=40, divided into two groups of 20 mice each) were randomized to receive ad libitum diet or restricted-calorie diet. Two mice from each group were sacrificed at 3 and 6 months, and liver tissue samples were removed for analysis. The remaining mice were fed their respective diets until the age of 30 months, at which time they were euthanized and livers were collected for analysis.

RESULTS

The restricted-calorie diet had partial chemopreventive effect on the development of HCC in Mdr2(-/-) mice. Moreover, mice with ad libitum diet had a median survival of 361 days, while the restricted-calorie group had a median survival of 500 days (p=0.0001).

CONCLUSION

A restricted diet might reduce the chance of developing HCC in patients at risk and could increase the protective action of anti-inflammatory agents.

A case of advanced second-degree atrioventricular block in a ferret secondary to lymphoma

A female ferret was referred as an emergency for severe respiratory distress symptoms. At presentation, the patient was listlessness, dyspnoeic, and hyper-responsive. The clinical examination evidenced dyspnea with cyanosis, altered cardiac rhythm, and hepatomegaly. Electrocardiography showed an advanced second-degree atrioventricular (AV) block. The liver aspirate was diagnostic for lymphoma. The patient did not respond to supportive therapy and rapidly died. Post-mortem exams confirmed the presence of lymphoma with hepatic involvement. Moreover, a pericardial lymphocytic infiltration and a widespread myocardial nodular localization of lymphoma were evidenced as well. This condition was probably the cause of the cardiac arrhythmia. To the best of our knowledge, ours is the first report of cardiac lymphoma causing heart block in ferrets.

Surgery and electrochemotherapy for the treatment of cutaneous squamous cell carcinoma in a yellow-bellied slider (Trachemys scripta scripta)

CASE DESCRIPTION

A 5-year-old female yellow-bellied slider (Trachemys scripta scripta) was referred for evaluation of a 2-month nonhealing ulcerated mass on the dorsal aspect of the neck.

CLINICAL FINDINGS

The turtle was quiet, alert, and responsive, with a 2 × 1.5-cm ulcerated lesion on the neck. Signs of discomfort were observed during manipulation of the neck; no other abnormalities were detected during physical evaluation.

TREATMENT AND OUTCOME

Following total body radiography and hematologic and serum biochemical analysis, the turtle was anesthetized and the mass was surgically removed. The excised tissue was submitted for histologic evaluation. A histopathologic diagnosis of squamous cell carcinoma (SCC) was made. Further surgical revision was not an option because of the extensive nature of the lesion; therefore, the tumor bed was treated with electrochemotherapy (ECT). Two sessions of ECT were performed with a 2-week interval between treatments. Electrochemotherapy involved intratumoral administration of bleomycin followed by trains of biphasic electric pulses. The treatment was well tolerated, and the turtle was disease free after 12 months.

CLINICAL RELEVANCE

ECT resulted in good local control of SCC and should be considered as a possible postsurgical adjuvant treatment in reptiles with cutaneous tumors.

Electroporation Enhances Bleomycin Efficacy in Cats with Periocular Carcinoma and Advanced Squamous Cell Carcinoma of the Head

Background

Advanced carcinoma of the head represents a substantial health problem in cats for local control and overall survival.

Objectives

Evaluate the capability of electrochemotherapy (ECT) to improve bleomycin efficacy in cats with periocular carcinoma and advanced carcinoma of the head.

Animals

Twenty‐one cats with periocular carcinoma (17 squamous cell carcinoma [SCC] and 4 anaplastic carcinoma) and 26 cats with advanced SCC of the head.

Methods

Nonrandomized prospective controlled study. Periocular carcinoma cohorts: 12 cats were treated with bleomycin (15 mg/m²IV) coupled with ECT under anesthesia; 9 cats were treated with bleomycin alone. Advanced head SCC cohorts: 14 cats were treated with bleomycin (15 mg/m²IV) coupled with ECT administered under sedation; 12 control cats were treated with bleomycin alone. ECT treatments (2–8) were performed every other week until complete remission (CR) or tumor progression occurred.

Results

Toxicities were minimal and mostly treated symptomatically. Overall response rate in the ECT treated animals was 89% (21 Complete Response [CR] and 2 Partial Response [PR]) whereas controls had response rate of 33% (4 CR and 3 PR). Median time to progression in ECT group was 30.5 months, whereas in controls it was 3.9 months (P < .0001). Median time to progression for ECT cohorts was 24.2 months for periocular cohort and 20.6 in advanced head SCC cohort, respectively.

Conclusions

Electrochemotherapy is well tolerated for advanced SCC of the head in cats; its use may be considered among loco‐regional strategies for cancer therapy in sensitive body regions such as periocular region.

High dose lansoprazole combined with metronomic chemotherapy: a phase I/II study in companion animals with spontaneously occurring tumors

BACKGROUND

The treatment of human cancer has been seriously hampered for decades by resistance to chemotherapeutic drugs. A very efficient mechanism of tumor resistance to drugs is the proton pumps-mediated acidification of tumor microenvironment. Metronomic chemotherapy has shown efficacy in adjuvant fashion as well as in the treatment of pets with advanced disease. Moreover, we have shown in veterinary clinical settings that pre-treatment with proton-pumps inhibitors (PPI) increases tumor responsiveness to chemotherapeutics. In this study pet with spontaneously occurring cancer have been recruited to be treated by a combination of metronomic chemotherapy and high dose PPIs and their responses have been matched to those of a historical control of ten patients treated with metronomic chemotherapy alone.

METHODS

Single arm, non randomized phase II open study, with historical control group, evaluating safety and efficacy of the combination of metronomic chemotherapy and alkalization. Twenty-four companion animals (22 dogs and 2 cats) were treated adding to their metronomic chemotherapy protocol the pump inhibitor lansoprazole at high dose, and a water alkalizer. Their responses have been evaluated by clinical and instrumental evaluation and matched to those of the control group.

RESULTS

The protocol was overall well tolerated, with only two dogs experiencing side effects due to gastric hypochlorhydria consisting with vomiting and or diarrhea. In terms of overall response, in the alkalized cohort, 18 out of 24 had partial or complete responses (75%), two patients had a stable disease and the remaining patients experienced no response or progressive disease. On the other hand, only one patient in the control group experienced a complete response (10%) and three other experienced short lived responses. Median time to terminal event was 34 weeks for the experimental group versus 2 weeks in the controls (p= 0.042).

CONCLUSIONS

Patient alkalization has shown to be well tolerated and to increase tumor response to metronomic chemotherapy as well the quality of life in pets with advanced cancer. Further studies are warranted to assess the efficacy of this strategy in patients with advanced cancers in companion animals as well as in humans.

Definition of novel electrochemotherapy parameters and validation of their in vitro and in vivo effectiveness

Electrochemotherapy (ECT) is a cancer therapy that conjugates the administration of a chemotherapy agent to the delivery of permeabilizing pulses released singularly or as bursts. This approach results in higher number of anticancer molecules delivered to their biological targets, but is also associated to undesirable side effects such as pain and muscular contractions. A new electroporator delivering train of eight biphasic pulses at the voltage of 1,300 V/cm lasting 50 + 50 µsec each, with a frequency of 1 Hz, and with 10-µsec interpulse intervals (total treatment time: 870 µsec/cm(2) of treated area) was tested in vitro on the human lung cancer cell line A549 and in vivo, both in mice xenografts and privately owned rabbits with spontaneous tumors. The tumor cell line was treated with electroporation using the new parameters, that showed improved drug efficacy in causing cell death. Mice with chemoresistant xenografts were treated as well with either the new parameters and with a previous protocol, confirming the higher tolerability and efficacy of the novel parameters. Finally, a cohort of six pet rabbits with advanced skin neoplasms were enrolled in a compassionate trial using the new parameters in adjuvant fashion. In terms of efficacy, none of the rabbits experienced tumor recurrence, showing minimal discomfort during the ECT sessions. The data described, demonstrate that the new permeabilizing protocol adopting biphasic electric pulses displays a significant higher efficacy compared to previous ECT treatments and substantial reduction of the associated morbidity.

Electrochemotherapy in veterinary oncology: from rescue to first line therapy

Electroporation is a delivery technique that is gaining popularity among the veterinary community due to its low cost, ease of application, and flexibility. It combines the administration of pharmaceutical compounds such as chemotherapy agents, antisense, and plasmids to the application of permeabilizing pulses. This chapter reviews the veterinary results obtained through the delivery of anticancer drugs (electrochemotherapy) and genes (electro-gene therapy).

Functional and pharmacodynamic evaluation of metronomic cyclophosphamide and docetaxel regimen in castration-resistant prostate cancer

Aim: The aim of our study was to investigate the association of docetaxel and metronomic cyclophosphamide (CYC) in castration-resistant prostate cancer (CRPC). Materials & methods: CRPC xenografts were established with PC3 cells. Mice were treated with a combination of CYC (50 mg/kg/day) and docetaxel (10–30 mg/kg/week) or with docetaxel alone. Docetaxel plasma levels were analyzed in patients receiving the drug alone or combined with CYC. Results: Metronomic CYC is an effective adjuvant in blocking tumor growth in vivo, with comparable efficacy and less toxic effects compared with docetaxel treatment. CYC acts by downregulating cell proliferation and inducing apoptosis thorough upregulation of p21 and inhibition of angiogenesis. Finally, CYC increases docetaxel plasma levels in patients. Conclusion: Metronomic CYC exerts anti-tumoral effects in an in vivo model of prostate cancer and in patients with CRPC, and also increases the bioavailability of docetaxel. These results explain the favorable toxicity and activity profiles observed in patients treated with this regimen.

Electroporation as a strategy to promote HtrA1 gene uptake and chemotherapy efficacy in a mouse model of mesothelioma

There is not a consensus on the best therapeutic approach to mesothelioma and the prognosis is still dismal. We have recently demonstrated that HtrA1 is a potential therapeutic target in mesothelioma cells. In this manuscript we describe that electroporation in a mouse mesothelioma xenograft was able to facilitate the expression of exogenous HtrA1 injected intra-lesionally in the tumors and to increase the penetration in the neoplastic cells of cisplatin given intra-peritoneally. Indeed, HtrA1 over-expression caused a significant slowing down of tumor growth; moreover, cisplatin efficacy in reducing tumor mass was amplified by electroporation and this phenomenon was even more significant when combining the electroporation of cisplatin and HtrA1. Considering that a substantial number of mesothelioma patients develop early local recurrence, even with radical resection combined with aggressive chemo- and radiotherapy, this multi-modality approach could be very effective in improving local tumor control after surgery. The identification of effective combination coupled with the development of novel equipments and electrodes will be instrumental in planning the translation of these results to humans as per correct laboratory-clinical interface.

Electrochemotherapy for the treatment of recurring aponeurotic fibromatosis in a dog

This paper reports the clinical findings, histopathology, and clinical outcome of a rare case of aponeurotic fibromatosis in a dog. The dog was treated with 4 courses of electrochemotherapy using the drugs cisplatin and bleomycin. There was complete remission and the dog was still disease-free after 18 months.

Inhibition of p85, the non-catalytic subunit of phosphatidylinositol 3-kinase, exerts potent antitumor activity in human breast cancer cells

The phosphoinositide 3-kinases (PI3Ks) are heterodimers consisting of the catalytic subunit p110 and the regulatory subunit p85. The PI3K/Akt pathway is strongly deregulated in breast cancer (BC) representing one of the mechanisms of resistance to therapies. Therefore, the identification of inhibitors of PI3K components represents one of the main goals to produce therapeutic agents. Here, we evaluated the efficacy of a phosphopeptide 1257 (P-1257) that targeting p85 strongly inhibits PI3K activity. We tested the effects of P-1257 administration in vitro and in vivo using BC cells expressing different levels of ErbB-2 and resistant or responsive to Trastuzumab. We demonstrated that inhibition of p85 activity by P-1257 induces cell death and sensitizes JIMT-1 and KPL-4 ErbB-2-overexpressing BC cells to Trastuzumab treatment. It is noteworthy that P-1257 delivery in vivo by electroporation or liposomes significantly inhibits the proliferation of tumor cells engrafted at subcutaneous and visceral sites. Overall, our data indicate that the p85 subunit is a valid target for therapeutic approaches and suggest that the structure of the peptide used in our study could be utilized for the development of novel drugs to apply in combination with therapies that fail to cure BCs with high PI3K activity.

Endocrine disruptors in utero cause ovarian damages linked to endometriosis

Timed pregnant Balb-C mice were treated from day 1 of gestation to 7 days after delivery with the endocrine disruptor bisphenol a (BPA) (100, or 1,000 microg/kg/day). After delivery, pups were hold for three months; then, ovaries were analyzed in their entirety. We found that in the ovaries of BPA-treated animals the number of primordial follicles and of developing follicles was significantly lower than in the untreated animals. Moreover, the number of atretic follicles was significantly higher in the treated animals. Finally, we found that the animals displaying endometriosis-like phenotype had a more severe impairment of the ovaries in term of number of primordial and developing follicles in comparison with the other mice exposed to BPA. In conclusion, we describe for the first time a complex phenotype in mice, elicited by pre-natal exposition to BPA, that includes ovarian lesions and endometriosis. Considering the high incidence of endometriosis and of the premature ovarian failure associated to infertility in these patients, the data showed prompt a thoroughly reconsideration of the pathological framing of these lesions.

Differential accumulation of BPA in some tissues of offspring of Balb-C mice exposed to different BPA doses

Pregnant adult Balb-C mice were exposed daily to two different doses of Bisphenol A (BPA) by subcutaneous injection beginning on gestational day 1 through the seventh day after delivery. The mothers were sacrificed on postpartum day 21, and the offspring were sacrificed at 3 months of age. Control mice were subjected to the same experimental protocol but received saline injections. The liver, muscles, hindbrain and forebrain of the offspring were dissected and processed using HPLC to assess the level of BPA in the tissues and to determine its dependence on the exposure dose and gender. For comparison, the same tissues were dissected from the mothers and analysed. We report the following results: (1) the level of BPA that accumulated in a given tissue was dependent on the exposure dose; (2) the rank order of BPA accumulation in the various tissues was dependent on the gender of the offspring; (3) the average BPA concentrations in the liver and muscle of the female offspring were higher than in the males; and (4) the average BPA concentration in the central nervous system (i.e., the hindbrain and forebrain) of the male offspring was higher than in the females.

Lansoprazole as a rescue agent in chemoresistant tumors: a phase I/II study in companion animals with spontaneously occurring tumors

BACKGROUND

The treatment of human cancer has been seriously hampered for decades by resistance to chemotherapeutic drugs. Mechanisms underlying this resistance are far from being entirely known. A very efficient mechanism of tumor resistance to drugs is related to the modification of tumour microenvironment through changes in the extracellular and intracellular pH. The acidification of tumor microenvironment depends on proton pumps that actively pump protons outside the cells, mostly to avoid intracellular acidification. In fact, we have shown in pre-clinical settings as pre-treatment with proton-pumps inhibitors (PPI) increase tumor cell and tumor responsiveness to chemotherapeutics. In this study pet with spontaneously occurring cancer proven refractory to conventional chemotherapy have been recruited in a compassionate study.

METHODS

Thirty-four companion animals (27 dogs and 7 cats) were treated adding to their chemotherapy protocols the pump inhibitor lansoprazole at high dose, as suggested by pre-clinical experiments. Their responses have been compared to those of seventeen pets (10 dogs and 7 cats) whose owners did not pursue any other therapy than continuing the currently ongoing chemotherapy protocols.

RESULTS

The drug was overall well tolerated, with only four dogs experiencing side effects due to gastric hypochlorhydria consisting with vomiting and or diarrhea. In terms of overall response twenty-three pets out of 34 had partial or complete responses (67.6%) the remaining patients experienced no response or progressive disease however most owners reported improved quality of life in most of the non responders. On the other hand, only three animals in the control group (17%) experienced short lived partial responses (1-3 months duration) while all the others died of progressive disease within two months.

CONCLUSIONS

high dose proton pump inhibitors have been shown to induce reversal of tumor chemoresistance as well as improvement of the quality of life in pets with down staged cancer and in the majority of the treated animals PPI were well tolerated. Further studies are warranted to assess the efficacy of this strategy in patients with advanced cancers in companion animals as well as in humans.

Tumor suppressors and cell-cycle proteins in lung cancer

The cell cycle is the cascade of events that allows a growing cell to duplicate all its components and split into two daughter cells. Cell cycle progression is mediated by the activation of a highly conserved family of protein kinases, the cyclin-dependent kinases (CDKs). CDKs are also regulated by related proteins called cdk inhibitors grouped into two families: the INK4 inhibitors (p16, p15, p19, and p18) and the Cip/Kip inhibitors (p21, p27, and p53). Several studies report the importance of cell-cycle proteins in the pathogenesis and the prognosis of lung cancer. This paper will review the most recent data from the literature about the regulation of cell cycle. Finally, based essentially on the data generated in our laboratory, the expression, the diagnostic, and prognostic significance of cell-cycle molecules in lung cancer will be examined.

Electrochemotherapy with cisplatin enhances local control after surgical ablation of fibrosarcoma in cats: an approach to improve the therapeutic index of highly toxic chemotherapy drugs

Background

Cancer is one of the most difficult current health challenges, being responsible for millions of deaths yearly. Systemic chemotherapy is the most common therapeutic approach, and the prevailing orientation calls for the administration of the maximum tolerated dose; however, considerable limitations exist including toxicities to healthy tissues and low achievable drug concentrations at tumor sites. Electrochemotherapy (ECT) is a tumor treatment that combines the systemic or local delivery of anticancer drugs with the application of permeabilizing electric pulses. In this article we evaluate the capability of ECT to allow the use of cisplatin despite its high toxicity in a spontaneous feline model of soft tissue sarcoma.

Methods

A cohort of sixty-four cats with incompletely excised sarcomas were treated with cisplatin-based adjuvant ECT and monitored for side effects. Their response was compared to that of fourteen cats treated with surgery alone.

Results

The toxicities were minimal and mostly treated symptomatically. ECT resulted in increased local control (median not reached at the time of writing) with a mean time to recurrence of 666 days versus 180 of controls.

Conclusions

We conclude that ECT is a safe and efficacious therapy for solid tumors; its use may be considered as part of strategies for the reintroduction of drugs with a narrow therapeutic index in the clinical protocols.

Apoptosis induced by piroxicam plus cisplatin combined treatment is triggered by p21 in mesothelioma

BACKGROUND

Malignant mesothelioma (MM) is a rare, highly aggressive tumor, associated to asbestos exposure. To date no chemotherapy regimen for MM has proven to be definitively curative, and new therapies for MM treatment need to be developed. We have previously shown in vivo that piroxicam/cisplatin combined treatment in MM, specifically acts on cell cycle regulation triggering apoptosis, with survival increase.

METHODOLOGY/PRINCIPAL FINDINGS

We analyzed, at molecular level, the apoptotic increase caused by piroxicam/cisplatin treatment in MM cell lines. By means of genome wide analyses, we analyzed transcriptional gene deregulation both after the single piroxicam or cisplatin and the combined treatment. Here we show that apoptotic increase following combined treatment is mediated by p21, since apoptotic increase in piroxicam/cisplatin combined treatment is abolished upon p21 silencing.

CONCLUSIONS/SIGNIFICANCE

Piroxicam/cisplatin combined treatment determines an apoptosis increase in MM cells, which is dependent on the p21 expression. The results provided suggest that piroxicam/cisplatin combination might be tested in clinical settings in tumor specimens that express p21.

Electroporation increases antitumoral efficacy of the bcl-2 antisense G3139 and chemotherapy in a human melanoma xenograft

BACKGROUND

Nucleic acids designed to modulate the expression of target proteins remain a promising therapeutic strategy in several diseases, including cancer. However, clinical success is limited by the lack of efficient intracellular delivery. In this study we evaluated whether electroporation could increase the delivery of antisense oligodeoxynucleotides against bcl-2 (G3139) as well as the efficacy of combination chemotherapy in human melanoma xenografts.

METHODS

Melanoma-bearing nude mice were treated i.v. with G3139 and/or cisplatin (DDP) followed by the application of trains of electric pulses to tumors. Western blot, immunohistochemistry and real-time PCR were performed to analyze protein and mRNA expression. The effect of electroporation on muscles was determined by histology, while tumor apoptosis and the proliferation index were analyzed by immunohistochemistry. Antisense oligodeoxynucleotides tumor accumulation was measured by FACS and confocal microscopy.

RESULTS

The G3139/Electroporation combined therapy produced a significant inhibition of tumor growth (TWI, more than 50%) accompanied by a marked tumor re-growth delay (TRD, about 20 days). The efficacy of this treatment was due to the higher G3139 uptake in tumor cells which led to a marked down-regulation of bcl-2 protein expression. Moreover, the G3139/EP combination treatment resulted in an enhanced apoptotic index and a decreased proliferation rate of tumors. Finally, an increased tumor response was observed after treatment with the triple combination G3139/DDP/EP, showing a TWI of about 75% and TRD of 30 days.

CONCLUSIONS

These results demonstrate that electroporation is an effective strategy to improve the delivery of antisense oligodeoxynucleotides within tumor cells in vivo and it may be instrumental in optimizing the response of melanoma to chemotherapy. The high response rate observed in this study suggest to apply this strategy for the treatment of melanoma patients.

Identification of protein-protein interactions of human HtrA1

The human heat shock protein HtrA1, a member of the HtrA family of serine proteases, is a evolutionarily highly conserved factor which displays a widespread pattern of expression. The yeast two-hybrid technique was employed to identify new cellular proteins physically interacting with HtrA1, and thus potential targets of this serine protease. An enzymatically inactive HtrA1 point mutant, HtrA1-S328A, was generated and used as bait in a yeast two-hybrid system. Fifty-two plasmids were isolated from primary positive yeast clones. Subsequent sequencing and BLAST analysis revealed cDNAs encoding for 13 different proteins. These putative binding partners of HtrA1 appeared to be a) components of extracellular matrix; b) factors related to signal pathways, and c) unknown proteins. Among the 13 positive clones identified and reported here, it is worth of note that the interaction of HtrA1 with tubulin and collagen (extracellular matrix proteins) and with tuberin (cytoplasmic protein) is confirmed by other studies, and this further supports previous findings in which HtrA1 can be found active as an intracytoplasmic protein or as secreted protein as well.

Evaluation of Cisplatin as an electrochemotherapy agent for the treatment of incompletely excised mast cell tumors in dogs

BACKGROUND

Electrochemotherapy (ECT) couples the administration of anticancer drugs with the delivery of electric pulses that increase the drug uptake through the cell membranes, resulting in an improved efficacy.

HYPOTHESIS

To evaluate the tolerability and efficacy of cisplatin (CDDP) as an ECT agent to prevent recurrence of incompletely resected mast cell tumors (MCTs).

ANIMALS

Thirty-seven dogs.

METHODS

Prospective study recruiting dogs with incompletely excised MCTs as confirmed by surgeon and pathology reports. After debulking, the tumor bed and margins were infiltrated with CDDP, and then exposed to trains of biphasic electrical pulses under sedation. Five minutes after the injection of the chemotherapy agent, sequences of 8 biphasic pulses lasting 50 + 50 μs each, were delivered in bursts of 1,300 V/cm for sclerosed and of 800 V/cm for exposed lesions, with caliper or needle array electrodes, respectively. A second session was performed 1 or 2 weeks later based on clinical considerations.

RESULTS

The treatment was well tolerated with minimal adverse effects. Twenty-nine dogs had no evidence of recurrence over the 6-year study period, 6 had tumor recurrence, 1 died of multiple cutaneous MCTs, and 1 died of unrelated causes. The estimated median time to recurrence was 1,200 days. Recurrence was not observed among the long-term (> 1 year) treated dogs.

CONCLUSIONS AND CLINICAL IMPORTANCE

ECT with CDDP appears effective in the treatment of incompletely resected MCT in dogs and could be a useful addition to the current options based on its low cost, limited toxicity, and ease of administration.

Pre-natal exposure of mice to bisphenol A elicits an endometriosis-like phenotype in female offspring

Endometriosis is a chronic gynecological disease characterized by the growth of endometrial tissue outside the uterine cavity. Exposure to endocrine disruptors during critical period of development causes long-lasting effects, being the genital system one of the targets. This study describes the effects on female genital system caused by developmental exposure to the endocrine-disrupting chemical bisphenol A (BPA) during pre- and peri-natal development in mice. To this end, timed pregnant Balb-C mice were treated from day 1 of gestation to 7 days after delivery with BPA (100, or 1000 microg/kg/day). After delivery, pups were held for 3 months; then, pelvic organs were analyzed in their entirety and livers of both pups and moms were studied for the presence of BPA. We found in the adipose tissue surrounding the genital tracts of a consistent number of treated animals, endometriosis-like structure with the presence of both glands and stroma and expressing both estrogen receptor and HOXA-10. Moreover, cystic ovaries, adenomatous hyperplasia with cystic endometrial hyperplasia and atypical hyperplasia were significantly more frequent in treated animals respect to the controls. Finally, BPA was found in the livers of exposed moms and female offspring. In conclusion, we describe for the first time an endometriosis-like phenotype in mice, elicited by pre-natal exposition to BPA. This observation may induce to thoroughly reconsider the pathogenesis and treatment of endometriosis, considering the high incidence of endometriosis and the problems caused by associated infertility.

Biological agents involved in malignant mesothelioma: relevance as biomarkers or therapeutic targets

Malignant mesothelioma (MM) is a rare, highly aggressive tumor that arises from the surface serosal cells (pleural, peritoneal and pericardial cavities). Epidemiological and clinical data show that there is an association between asbestos exposure and MM development, even if the exact mechanism whereby asbestos induces MM is unknown. The continuing identification and elucidation of the molecular defects involved in mesothelioma pathogenesis and progression should lead to better disease control and greater therapeutic options in the near future. Goal of this article is to summarize the most recent advances in molecular pathogenesis of mesothelioma with particular emphasis on genes that could be considered as biomarkers or therapeutic targets and discuss possible clinical implications of these findings.

Molecular, cellular and physiological characterization of the cancer cachexia-inducing C26 colon carcinoma in mouse

BACKGROUND

The majority of cancer patients experience dramatic weight loss, due to cachexia and consisting of skeletal muscle and fat tissue wasting. Cachexia is a negative prognostic factor, interferes with therapy and worsens the patients' quality of life by affecting muscle function. Mice bearing ectopically-implanted C26 colon carcinoma are widely used as an experimental model of cancer cachexia. As part of the search for novel clinical and basic research applications for this experimental model, we characterized novel cellular and molecular features of C26-bearing mice.

METHODS

A fragment of C26 tumor was subcutaneously grafted in isogenic BALB/c mice. The mass growth and proliferation rate of the tumor were analyzed. Histological and cytofluorometric analyses were used to assess cell death, ploidy and differentiation of the tumor cells. The main features of skeletal muscle atrophy, which were highlighted by immunohistochemical and electron microscopy analyses, correlated with biochemical alterations. Muscle force and resistance to fatigue were measured and analyzed as major functional deficits of the cachectic musculature.

RESULTS

We found that the C26 tumor, ectopically implanted in mice, is an undifferentiated carcinoma, which should be referred to as such and not as adenocarcinoma, a common misconception. The C26 tumor displays aneuploidy and histological features typical of transformed cells, incorporates BrdU and induces severe weight loss in the host, which is largely caused by muscle wasting. The latter appears to be due to proteasome-mediated protein degradation, which disrupts the sarcomeric structure and muscle fiber-extracellular matrix interactions. A pivotal functional deficit of cachectic muscle consists in increased fatigability, while the reported loss of tetanic force is not statistically significant following normalization for decreased muscle fiber size.

CONCLUSIONS

We conclude, on the basis of the definition of cachexia, that ectopically-implanted C26 carcinoma represents a well standardized experimental model for research on cancer cachexia. We wish to point out that scientists using the C26 model to study cancer and those using the same model to study cachexia may be unaware of each other's works because they use different keywords; we present strategies to eliminate this gap and discuss the benefits of such an exchange of knowledge.

Proton pump inhibitors as anti vacuolar-ATPases drugs: a novel anticancer strategy

The vacuolar ATPases are ATP-dependent proton pumps whose functions include the acidification of intracellular compartments and the extrusion of protons through the cell cytoplasmic membrane. These pumps play a pivotal role in the regulation of cell pH in normal cells and, to a much greater extent, in tumor cells. In fact, the glucose metabolism in hypoxic conditions by the neoplasms leads to an intercellular pH drift towards acidity. The acid microenvironment is modulated through the over-expression of H+ transporters that are also involved in tumor progression, invasiveness, distant spread and chemoresistance. Several strategies to block/downmodulate the efficiency of these transporters are currently being investigated. Among them, proton pump inhibitors have shown to successfully block the H+ transporters in vitro and in vivo, leading to apoptotic death. Furthermore, their action seems to synergize with conventional chemotherapy protocols, leading to chemosensitization and reversal of chemoresistance. Aim of this article is to critically revise the current knowledge of this cellular machinery and to summarize the therapeutic strategies developed to counter this mechanism.

Adjuvant electrochemotherapy in veterinary patients: a model for the planning of future therapies in humans

The treatment of soft tissue tumors needs the coordinated adoption of surgery with radiation therapy and eventually, chemotherapy. The radiation therapy (delivered with a linear accelerator) can be preoperative, intraoperative, or postoperative. In selected patients adjuvant brachytherapy can be adopted. The goal of these associations is to achieve tumor control while maximally preserving the normal tissues from side effects. Unfortunately, the occurrence of local and distant complications is still elevated. Electrochemotherapy is a novel technique that combines the administration of anticancer agents to the application of permeabilizing pulses in order to increase the uptake of antitumor molecules. While its use in humans is still confined to the treatment of cutaneous neoplasms or the palliation of skin tumor metastases, in veterinary oncology this approach is rapidly becoming a primary treatment. This review summarizes the recent progresses in preclinical oncology and their possible transfer to humans.

Electrochemotherapy for the treatment of squamous cell carcinoma in cats: A preliminary report

Squamous cell carcinomas (SCC) of the skin are commonly described in cats. Reported treatments include surgery, radiation therapy and photodynamic therapy. This preliminary study reports on the management of these lesions combining the local administration of bleomycin (plus hyaluronidase for a more uniform distribution) with permeabilizing biphasic electric pulses. Nine cats with SCC graded T(2)-T(4) were treated over a 5 year period, and each cat received two sessions of electrochemotherapy (ECT) 1 week apart. The side effects of this treatment were minimal and limited to mild erythema of the nose. Seven of the cats (77.7%) had a complete response lasting up to 3 years. ECT seems to be a safe and effective option for the treatment of feline sun-induced squamous cell carcinomas and warrants further investigation.

Biphasic pulses enhance bleomycin efficacy in a spontaneous canine genital tumor model of chemoresistance: Sticker sarcoma

Sticker's sarcoma (also known as transmissible venereal tumor) is a horizontally transmitted neoplasm of the dog, that is passed with coitus. It is a locally aggressive tumor with a low tendency to metastatic spread. The most common locations are the genitals, the nose, the perianal area. Standard treatment consists with chemotherapy with vincristine, however other therapies such as, cryotherapy, immunotherapy or, in selected cases, radiation therapy, have been reported. In this article we describe the outcome of a small cohort of canine patients, with chemotherapy resistant transmissible venereal tumor (TVT), treated with bleomycin selectively driven by trains of biphasic pulses (electrochemotherapy). Three canine patients, with refractory TVT, entered the study and received two sessions of ECT under sedation. The pets had local injection of bleomycin at the concentration of 1.5 mg/ml and five minutes after the chemotherapy, trains of 8 biphasic electric pulses lasting 50 + 50 μs each, with 1 ms interpulse intervals, were delivered by means of modified caliper or, for difficult districts, through paired needle electrode. All the patients responded to the treatment and are still in remission at different times. Electrochemotherapy appears as a safe and efficacious modality for the treatment of TVT and warrants further investigations.

Adjuvant carboplatin for the treatment of intestinal carcinoid in a dog

A ten-year-old castrated male dog was presented due to a two-day history of constipation and tenesmus. At physical examination, the dog was depressed and unresponsive. Aggressive behavior was elicited by deep abdominal palpation and a mass was detected during the examination. Imaging studies evidenced a large jejunal mass. The lesion (6 cm in diameter) was surgically removed. The histopathology report gave a diagnosis of completely excised intestinal carcinoid. The patient recovered well from the procedure and was scheduled for adjuvant chemotherapy. The dog received four doses of carboplatin (300 mg/m2) every three weeks without showing signs of toxicity. The dog is still in remission after 18 months and is reassessed on a three-month schedule. This report represents the first description of long-term control of intestinal carcinoid in the dog and the first of adjuvant chemotherapy for this rare and aggressive neoplasm.

Electrochemotherapy-induced radiation recall in a cat

Electrochemotherapy is gaining popularity for the treatment of malignancies of companion animals due to its efficacy and low cost. In this paper, we describe the successful treatment of a recurring fibrosarcoma in a cat by using cisplatin selectively driven within the tumor cells by trains of biphasic pulses. The cat's tumor did not recur over the following five months, however the cat did experience severe erythema at the site of previous irradiation, followed by moist desquamation and ulcer that required debridement and prolonged therapy with steroids and antihistaminic drugs. The symptoms and the response to symptomatic therapy were strongly suggestive of radiation recall. Electrochemotherapy (ECT) should be used with caution in previously irradiated areas. Further studies are warranted in this field due to its potential as a rescue for relapsing tumors.

Prostate as sole unusual recurrence site of lymphoma in a dog

A ten-year-old intact male Rottweiler dog was examined for sudden onset of stranguria and pollakiuria. The dog had an intestinal lymphoma treated three years before with chemotherapy. Ultrasonographic examination of the abdomen showed a large dyshomogeneous prostate with an over-distended bladder. Cytological examination of the fine-needle aspirate from the prostate yielded a diagnosis of lymphoma. The diagnosis was confirmed by histopathological examination. The dog was treated with multi-drug chemotherapy and achieved a complete remission. The dog remained in complete remission for one year from the re-institution of chemotherapy before dying of recurrence. Lymphoma rarely invades the prostate in the dog. To the best of our knowledge this is the first report of prostatic recurrence of lymphoma in a canine patient originally affected by intestinal lymphoma and treated with chemotherapy.

The serine protease HtrA1 is a novel prognostic factor for human mesothelioma

AIMS

The objective of our study was to analyze the potential prognostic value of the expression of the serine protease HtrA1 and of EGFR in 70 malignant mesotheliomas.

MATERIALS & METHODS

Immunohistochemistry was used to determine the expression of HtrA1 and EGFR. Univariate and multivariate analyses were used to correlate expression of these molecular factors in combination with available clinicopathologic data to patient survival.

RESULTS

A positive, statistically significant relationship has been recorded between HtrA1 expression level and survival (p < 0.0001). By contrast, a negative relationship has been identified between EGFR expression and survival (p = 0.02). Moreover, extension of the tumor (T) and involvement of lymph nodes (N) advanced status (p = 0.001 and 0.002, respectively), as well as the sarcomatoid histotype (p = 0.005), correlated significantly with poor survival. Finally, by a multivariate Cox regression analysis, the only immunohistochemical parameter that resulted to influence overall survival was HtrA1 (p = 0.0001). Interestingly, the prognostic value of HtrA1 expression was completely independent from EGFR expression (p < 0.0001).

CONCLUSION

This is the first study of the relationship between HtrA1 expression and survival of mesothelioma patients. The data obtained strongly indicate the utilization of HtrA1 expression as a prognostic parameter for mesothelioma and suggest this serine protease as a possible molecular target for the treatment of malignant mesotheliomas.