Exploring the Spatial Drug Distribution Pattern of Pressurized Intraperitoneal Aerosol Chemotherapy (PIPAC)

PIPAC for Gastrointestinal Malignancies

The peritoneum is a common site of metastases for gastrointestinal tumors that predicts a poor outcome. In addition to decreased survival, peritoneal metastases (PMs) can significantly impact quality of life from the resulting ascites and bowel obstructions. The peritoneum has been a target for regional therapies due to the unique properties of the blood-peritoneum barrier. Cytoreductive surgery (CRS) and heated intraperitoneal chemotherapy (HIPEC) have become accepted treatments for limited-volume peritoneal disease in appendiceal, ovarian, and colorectal malignancies, but there are limitations. Pressurized intraperitoneal aerosolized chemotherapy (PIPAC) improves drug distribution and tissue penetration, allowing for a minimally invasive application for patients who are not CRS/HIPEC candidates based on high disease burden. PIPAC is an emerging treatment that may convert the patient to resectable disease, and may increase survival without major morbidity, as indicated by many small studies. In this review, we discuss the rationale and benefits of PIPAC, as well as sentinel papers describing its application for gastric, colorectal, appendiceal, and pancreatobiliary PMs. While no PIPAC device has yet met FDA approval, we discuss next steps needed to incorporate PIPAC into neoadjuvant/adjuvant treatment paradigms, as well as palliative settings. Data on active clinical trials using PIPAC are provided.

Triple-Therapy of Peritoneal Metastasis-Partial-Dehydration under Hyperthermic Condition Combined with Chemotherapy: The First Preliminary In-Vitro Results

A newly introduced combination of intraperitoneal dehydration and hyperthermia has recently been shown to be feasible and cytotoxic for colon cancer cells in vivo. For the first time, our study now aims to evaluate dehydration under hyperthermic conditions combined with chemotherapy for potential use in the clinical setting. In this study, in vitro colon cancer cells (HT-29) were subjected to single or several cycles of partial dehydration under hyperthermic conditions (45 °C), followed by chemotherapy (triple exposure) with oxaliplatin or doxorubicin in various configurations. The viability, cytotoxicity, and proliferation of cells after the proposed protocols were assessed. Intracellular doxorubicin uptake was measured via flow cytometry. After one cycle of triple exposure, the viability of HT-29 cells was significantly reduced versus the untreated control (65.11 ± 5%, p < 0.0001) and versus only chemotherapy (61.2 ± 7%, p < 0.0001). An increased chemotherapeutic inflow into the cells after triple exposure was detected (53.4 ± 11%) when compared to cells treated with chemotherapy alone (34.23 ± 10%) (p < 0.001). Partial dehydration in a hyperthermic condition combined with chemotherapy increases the overall cytotoxicity of colon cancer cells significantly compared to chemotherapy alone. This could possibly be related to enhanced intracellular uptake of chemotherapeutic agents after partial dehydration. Further studies are required for the further evaluation of this new concept.

Optimal Nozzle Position and Patient's Posture to Enhance Drug Delivery into the Peritoneum during Rotational Intraperitoneal Pressurized Aerosol Chemotherapy in a Swine Model

Even though rotational intraperitoneal pressurized aerosol chemotherapy (RIPAC) has been developed to improve the distribution and penetration depth of anti-cancer agents by pressurized intraperitoneal aerosol chemotherapy (PIPAC), the optimal nozzle position and patient's posture have not been investigated. Thus, we used nine pigs weighing 50-60 kg, and sprayed 150 mL of 1% methylene blue as an aerosol through the nozzle, DreamPen^® (Dreampac Corp., Wonju, Republic of Korea), with a flow rate of 0.6 ml/min under a pressure of 140 to 150 psi for RIPAC in six and three pigs with supine and Trendelenburg positions, respectively. When we evaluated its distribution and penetration depth, even distribution among 13 regions of the abdomen was observed in three pigs with Trendelenburg position regardless of the depth of the nozzle. Regarding penetration depth, the numbers of regions with maximal penetration depth were high in the 2 cm depth of the nozzle with supine position (n = 5) and the 4 cm depth with Trendelenburg position (n = 3). Conclusively, even distribution and maximal penetration of anti-cancer agents can be expected during RIPAC in the medium depth (4 cm) between the nozzle inlet and the visceral peritoneum located on the opposite side of it and the Trendelenburg position.

Feasibility and Safety of Taxane-PIPAC in Patients with Peritoneal Malignancies-a Retrospective Bi-institutional Study

Taxanes have a favorable pharmacokinetic profile for intraperitoneal application. We report our initial experience with taxane-PIPAC (pressurized intraperitoneal chemotherapy) for unresectable peritoneal metastases from different primary sites in terms of safety, feasibility, response rate, and conversion to resectability. In this retrospective study, PIPAC was performed alone or in combination with systemic chemotherapy. Paclitaxel was used as a single agent, whereas docetaxel was used in combination with cisplatin-adriamycin or oxaliplatin-adriamycin. From December 2019 to December 2021, 47 patients underwent 82 PIPAC procedures (1 PIPAC in 55.3%, 2 in 29.7%, 3 in 14.8%). The most common primary sites were ovarian cancer (31.9%), gastric cancer (23.4%), and colorectal cancer (21.2%). Docetaxel-cisplatin-adriamycin was used in 33 (70.2%) patients, docetaxel-oxaliplatin-adriamycin in 12 (25.5%), and paclitaxel alone in 2 (4.2%) patients. Grade 1-2 complications were observed in 24 (51%) and grade 3-4 complications in 6 (12.7%) patients (8.5% of 82 PIPACs). 16/47 (34.0%) patients had a clinical response to PIPAC. The mean PCI was 25.9 ± 9.2 for the first PIPACs and 22.4 ± 9 for the subsequent PIPACs with an average reduction of 3.6 points [change in PCI ranged from - 14 to + 8]. The PRGS was 1/2 in 4/47 (8.5%) patients (19.0% patients with > 1 PIPAC). A reduction in ascites was observed in 35.4% presenting with ascites. Nine (19.1%) patients had conversion to operability leading to a subsequent cytoreductive surgery in 8 (17%) patients. PIPAC with docetaxel is feasible and safe. The role of PIPAC with both docetaxel and paclitaxel either alone or in combination with other drugs should be investigated in prospective studies.

Feasibility of pressurized intra peritoneal aerosol chemotherapy using an ultrasound aerosol generator (usPIPAC)

Background

We tested the feasibility of ultrasound technology for generating pressurized intraperitoneal aerosol chemotherapy (usPIPAC) and compared its performance vs. comparator (PIPAC).

Material and methods

A piezoelectric ultrasound aerosolizer (NextGen, Sinaptec) was compared with the available technology (Capnopen, Capnomed). Granulometry was measured for water, Glc 5%, and silicone oil using laser diffraction spectrometry. Two- and three-dimensional (2D and 3D) spraying patterns were determined with methylene blue. Tissue penetration of doxorubicin (DOX) was measured by fluorescence microscopy in the enhanced inverted Bovine Urinary Bladder model (eIBUB). Tissue DOX concentration was measured by high-performance liquid chromatography (HPLC).

Results

The droplets median aerodynamic diameter was (usPIPAC vs. PIPAC): H₂0: 40.4 (CI 10–90%: 19.0–102.3) vs. 34.8 (22.8–52.7) µm; Glc 5%: 52.8 (22.2–132.1) vs. 39.0 (23.7–65.2) µm; Silicone oil: 178.7 (55.7–501.8) vs. 43.0 (20.2–78.5) µm. 2D and 3D blue ink distribution pattern of usPIPAC was largely equivalent with PIPAC, as was DOX tissue concentration (usPIPAC: 0.65 (CI 5-95%: 0.44–0.86) vs. PIPAC: 0.88 (0.59–1.17) ng/ml, p = 0.29). DOX tissue penetration with usPIPAC was inferior to PIPAC: usPIPAC: 60.1 (CI 5.95%: 58.8–61.5) µm vs. PIPAC: 1172 (1157–1198) µm, p < 0.001). The homogeneity of spatial distribution (top, middle and bottom of the eIBUB) was comparable between modalities.

Discussion

usPIPAC is feasible, but its performance as a drug delivery system remains currently inferior to PIPAC, in particular for lipophilic solutions.

Is PIPAC a Treatment Option in Upper and Lower Gastrointestinal Cancer with Peritoneal Metastasis?

Background

The survival prognosis of patients with peritoneal metastasis (PM) of gastrointestinal (GI) cancer is generally poor and treatment consists of, according to international guidelines, systemic chemotherapy. A multimodal treatment approach, including cytoreductive surgery with or without hyperthermic intraperitoneal chemotherapy, not only proved to be beneficial mainly in colorectal cancer, but also in selected patients with gastric cancer. The authors performed systematic research of articles and ongoing clinical trials using the keywords "PIPAC" and "gastric cancer" or "colorectal cancer" in PubMed in October 2021. Key findings, such as complications rates, treatment protocols, and overall survival were summarized and illustrated in Tables and critically discussed.

Summary

Twenty years ago, the technique of Pressurized IntraPeritoneal Aerosol Chemotherapy (PIPAC) was developed by Reymond et al. and delivered evidence to be recognized as a basic therapeutic tool in this multimodal therapy. Currently, there are several ongoing Phase II and III trials exploring the usage and efficacy of PIPAC as a neoadjuvant, adjuvant, or palliative component of treatment in patients with PM of GI cancer.

Key Messages

The aim of this narrative review was to help navigate the reader throughout the most current evidence for the use PIPAC and to highlight its indication in patients with upper and lower GI cancer with PM. It also provides an outline of ongoing studies and future perspectives.

Hyperthermic Intraperitoneal Chemotherapy in the Treatment Armamentarium of Epithelial Ovarian Cancer: Time to End the Dichotomy

<b><i>Background:</i></b> Advanced epithelial ovarian cancer (EOC) is an incurable disease with over 75% of the patients developing recurrence in the peritoneum. Hyperthermic intraperitoneal chemotherapy (HIPEC) is a promising treatment option for both first-line therapy and treatment of recurrence. In this article, we review the rationale and current evidence for performing HIPEC and the role of HIPEC in the light of targeted systemic therapies. <b><i>Summary:</i></b> There are few randomized trials and several retrospective studies on the role of HIPEC in the management of EOC. A 12-month-overall survival (OS) benefit of the addition of HIPEC to interval cytoreductive surgery (CRS) was demonstrated in 1 randomized trial following which HIPEC has been included as a treatment option for this indication in several national/international guidelines. One retrospective propensity score-matched analysis showed a 16-month OS benefit of adding HIPEC to primary CRS. One randomized trial showed no benefit of the addition of carboplatin HIPEC to secondary CRS over secondary CRS alone. For patients undergoing primary CRS and secondary CRS for recurrence, the results of ongoing randomized trials are needed to define the role of HIPEC in these situations. All clinical trials have shown that the morbidity of HIPEC performed after CRS is acceptable. Along with the emergence of HIPEC as a promising surgical therapy, targeted therapies like bevacizumab and poly adenosine diphosphate-ribose polymerase inhibitors have been developed that have shown a survival benefit in selected patients. In principle, HIPEC and targeted therapies work in different ways and it is plausible to assume that their benefit could be additive, and their combination should be evaluated in clinical trials. The impact of prognostic factors like the disease extent, pathological response to systemic chemotherapy (SC), the histological subtype and molecular profile on the benefit of HIPEC, and targeted therapies has not been evaluated in clinical trials. <b><i>Key Messages:</i></b> HIPEC is an important therapeutic strategy in the treatment of EOC. While its role in patients undergoing interval CRS has been established, the results of ongoing randomized trials are needed to define its benefit at other time points. The morbidity of HIPEC in addition to CRS is acceptable. More research is needed to define subgroups that benefit most from HIPEC based on the extent of disease, response to SC, histology, and molecular profile. The combination of HIPEC and maintenance therapies should be evaluated in well-designed randomized clinical trials that evaluate not just the survival benefit and morbidity but also the cost-effectiveness of each therapy.

Development of a rat capnoperitoneum phantom to study drug aerosol deposition in the context of anticancer research on peritoneal carcinomatosis

Pressurized Intraperitoneal Aerosol Chemotherapy (PIPAC) is a promising approach with a high optimization potential for the treatment of peritoneal carcinomatosis. To study the efficacy of PIPAC and drugs, first rodent cancer models were developed. But inefficient drug aerosol supply and knowledge gaps concerning spatial drug distribution can limit the results based on such models. To study drug aerosol supply/deposition, computed tomography scans of a rat capnoperitoneum were used to deduce a virtual and a physical phantom of the rat capnoperitoneum (RCP). RCP qualification was performed for a specific PIPAC method, where the capnoperitoneum is continuously purged by the drug aerosol. In this context, also in-silico analyses by computational fluid dynamic modelling were conducted on the virtual RCP. The physical RCP was used for ex-vivo granulometric analyses concerning drug deposition. Results of RCP qualification show that aerosol deposition in a continuous purged rat capnoperitoneum depends strongly on the position of the inlet and outlet port. Moreover, it could be shown that the droplet size and charge condition of the drug aerosol define the deposition efficiency. In summary, the developed virtual and physical RCP enables detailed in-silico and ex-vivo analyses on drug supply/deposition in rodents.

Establishment of an Experimental System for Intraperitoneal Chemotherapy in a Rat Model

AIM

To establish an experimental system for comparing different methods of intraperitoneal chemotherapy in a rat model.

MATERIALS AND METHODS

We used six-week-old Sprague-Dawley rats, and created an early postoperative intraperitoneal chemotherapy (EPIC) system using 18-gauge syringes and evacuators, and a hyperthermic intraperitoneal chemotherapy (HIPEC) system using two peristaltic pumps which controlled the flow rate and temperature. Pressurized intraperitoneal aerosol chemotherapy (PIPAC) was achieved using a nozzle for dispersing aerosols at a flow rate up to 41.5 ml/min. The distribution and intensity of 0.2% trypan blue dye was compared among three methods.

RESULTS

The distribution was limited and the intensity was weak after EPIC, and the dye stained moderately in gravity-dependent regions after HIPEC. On the other hand, the distribution was the most comprehensive, and the intensity was the greatest after PIPAC.

CONCLUSION

This experimental system in a rat model may reflect the comparative effect among EPIC, HIPEC and PIPAC in humans.

HIPEC Methodology and Regimens: The Need for an Expert Consensus

BACKGROUND

Hyperthermic intraperitoneal chemotherapy (HIPEC) is performed with a wide variation in methodology, drugs, and other elements vital to the procedure. Adoption of a limited number of regimens could increase the collective experience of peritoneal oncologists, make comparison between studies more meaningful, and lead to a greater acceptance of results from randomized trials. This study aimed to determine the possibility of standardizing HIPEC methodology and regimens and to identify the best method of performing such a standardization.

METHODS

A critical review of preclinical and clinical studies evaluating the pharmacokinetic aspects of different HIPEC drugs and drug regimens, the impact of hyperthermia, and the efficacy of various HIPEC regimens as well as studies comparing different regimens was performed.

RESULTS

The preclinical and clinical data were limited, and studies comparing different regimens were scarce. Many of the regimens were neither supported by preclinical rationale or data nor validated by a dose-escalating formal phase 1 trial. All the regimens were based on pharmacokinetic data and did not take chemosensitivity of peritoneal metastases into account. Personalized medicine approaches such as patient-derived tumor organoids could offer a solution to this problem, although clinical validation is likely to be challenging.

CONCLUSIONS

Apart from randomized trials, more translational research and phases 1 and 2 studies are needed. While waiting for better preclinical and clinical evidence, the best way to minimize heterogeneity is by an expert consensus that aims to identify and define a limited number of regimens for each indication and primary site. The choice of regimen then can be tailored to the patient profile and its expected toxicity and the methodology according regional factors.

Development of rotational intraperitoneal pressurized aerosol chemotherapy to enhance drug delivery into the peritoneum

This study aims to evaluate the drug distribution, tissue concentrations, penetration depth, pharmacokinetic properties, and toxicities after rotational intraperitoneal pressurized aerosol chemotherapy (RIPAC) in pigs. Because relevant medical devices have not been introduced, we developed our prototype of pressurized intraperitoneal aerosol chemotherapy (PIPAC) and RIPAC by adding a conical pendulum motion device for rotating the nozzle. RIPAC and PIPAC were conducted using 150 ml of 1% methylene blue to evaluate the drug distribution and 3.5 mg of doxorubicin in 50 ml of 0.9% NaCl to evaluate the tissue concentrations and penetration depth, pharmacokinetic properties, and toxicities. All agents were sprayed as aerosols via the nozzle, DreamPen^® (Dalim Biotech, Gangwon, South Korea), with a velocity of 5 km/h at a flow rate of 30 ml/min under a pressure of 7 bars, and capnoperitoneum of 12 mmHg was maintained for 30 min. As a result, RIPAC showed a wider distribution and stronger intensity than PIPAC. Compared with PIPAC, RIPAC demonstrated high values of the tissue concentration in the central, right upper, epigastrium, left upper, left lower, right lower, and right flank regions (median, 375.5-2124.9 vs. 161.7-1240 ng/ml; p ≤ .05), and higher values of the depth of concentrated diffusion and depth of maximal diffusion (median, 232.5-392.7 vs. 116.9-240.1 μm; 291.2-551.2 vs. 250.5-362.4 μm; p ≤ .05) in all regions except for bowels. In RIPAC, the pharmacokinetic properties reflected hemodynamic changes during capnoperitoneum, and there were no related toxicities. Conclusively, RIPAC may have the potential to enhance drug delivery into the peritoneum compared to PIPAC.

The emergence of pressurized intraperitoneal aerosol chemotherapy as a palliative treatment option for patients with diffuse peritoneal metastases: a narrative review

Pressurized intraperitoneal aerosol chemotherapy (PIPAC) is an emerging palliative treatment for patients with unresectable peritoneal metastases. Potential advantages of PIPAC over current treatment options are a homogeneous intraperitoneal distribution, low local and systemic toxicity, and enhanced tumour penetration. Given these possible benefits, PIPAC is increasingly implemented in many centres worldwide. Scientific research into PIPAC is currently available from in vitro/in vivo/in animal studies, retrospective cohorts in humans, and phase I and II studies in humans. There are no results from randomised trials comparing PIPAC with conventional treatment, such as palliative systemic therapy. This narrative review aimed to provide an overview of the currently available literature on PIPAC. In general, repetitive PIPAC was feasible and safe for patients and operating room personnel. Primary and secondary non-access rates varied from 0-17% and 0-15%, respectively. Iatrogenic bowel injury was observed in 0-3% of PIPAC procedures. CTCAE grade 1-2 complications were common, mostly consisting of abdominal pain, nausea, vomiting, and fatigue. CTCAE grade 3-4 complications were uncommon, occurring on 0-15% of PIPAC procedures. Post-operative mortality rates of 0-2% were reported. The risk of occupational exposure to cytotoxic drugs was very low when strict safety guidelines were followed. Clinical heterogeneity was high in most studies, since, in general, patients with unresectable peritoneal metastases from a variety of primary tumours were included. Also, patients received either PIPAC monotherapy or PIPAC combined with concomitant systemic therapy, and were able to receive PIPAC in any line of palliative treatment. Since the results were generally not stratified for these three important factors, this severely complicates the interpretation of results. Based on the current literature, PIPAC may be regarded as a promising palliative treatment option in patients with diffuse peritoneal metastases. Initial results show that it is feasible and safe. However, well designed and (ideally) randomized controlled trials are urgently needed to determine the additional value of PIPAC in this setting. Until then, PIPAC should preferably be performed in the setting of clinical trials.

Pressurized intraperitoneal aerosol chemotherapy for recurrent ovarian, fallopian or primary peritoneal cancer with peritoneal carcinomatosis: a narrative review

For recurrent ovarian, fallopian or primary peritoneal cancer with peritoneal carcinomatosis (PC), it is challenging to resect tumors completely or to get complete remission by intravenous (IV) chemotherapy, and many patients show the resistance to various chemotherapeutic agents for IV chemotherapy ultimately. As an alternative, pressurized intraperitoneal aerosol chemotherapy (PIPAC) has been introduced for treating the disease, which delivers chemotherapeutic agents as an aerosol form while maintaining high intraperitoneal (IP) pressure. Based on preclinical studies, PIPAC showed better penetration depth and distribution of drugs into the peritoneum in comparison to conventional IP chemotherapy. Tumor regression on histology and peritoneal carcinomatosis index (PCI) has also been shown in relevant studies. In addition, most of the PIPAC procedures were completed successfully with acceptable toxicity due to the use of a low dose of chemotherapeutic agents. For considering these advantages of PIPAC, we review the current status of PIPAC for treating recurrent ovarian, fallopian or primary peritoneal cancer through literature review.

Pressurized intraperitoneal aerosol chemotherapy (PIPAC) for rare gynecologic indications: peritoneal metastases from breast and endometrial cancer

BACKGROUND

Peritoneal metastasis (PM) in patients with breast (BC) and endometrial cancer (EC) is rare and treatment options are limited. Pressurized IntraPeritoneal Aerosol Chemotherapy (PIPAC) has demonstrated efficacy against PM from various cancers, but its efficacy in BC/EC patients is unknown.

METHODS

Retrospective cohort study of patients with PM from BC/EC undergoing PIPAC with doxorubicin 1.5 mg/m² and cisplatin 7.5 mg/m². Data were collected within an international prospective PIPAC registry. Study outcomes were microscopic tumor regression grade (TRG), survival, adverse events (CTCAE), and quality of life (QoL).

RESULTS

150 PIPAC procedures in 44 patients (BC/EC = 28/16; mean age 58.8 ± 10.1 and 63.2 ± 10.1 years, respectively) were analyzed. The mean number of PIPACs per patient was 3 (range 0-9) and 3.5 (range 0-10), respectively. Primary/secondary non-access occurred in 4/3 of 150 (5%) procedures. PIPAC induced objective tumor regression as demonstrated by repetitive PM biopsies in 73% (32/44) of patients. Peri- and postoperative CTCAE grade 3 and 4 complications were observed in 12/150 (8%) of procedures. No grade 5 event was observed. After a median follow up of 5.7 (IQR 2.7-13.0) months, overall median survival was 19.6 (95% CI: 7.8-31.5) months (from first PIPAC). QoL indicators (general health, nausea, fatigue, constipation, pain, dyspnea, social, cognitive, emotional, and physical functioning) all improved or were maintained throughout PIPAC treatments.

CONCLUSIONS

Repetitive intraperitoneal chemotherapy with PIPAC is feasible and safe in patients with PM from BC and EC. PIPAC induces significant histological regression of PM while maintaining QoL.

Intraperitoneal chemotherapy of the peritoneal surface using high-intensity ultrasound (HIUS): investigation of technical feasibility, safety and possible limitations

Introduction: The penetration of chemotherapeutic drugs into peritoneal nodules remains at levels well below 1 mm, thus significantly limiting the antitumor effect of intraperitoneal chemotherapy (IPC). Recently, high-Intensity ultrasound (HIUS) has been discovered as a potential tool to significantly improve peritoneal diffusion rates. Despite promising preliminary data, basic aspects regarding its technical feasibility, safety and possible limitations remain unclear. This study aims to enhance our current understanding of HIUS and test its applicability using an ex-vivo swine model. Methods: Three postmortem swine were subject to laparotomy and consecutive lavage with 0.9%NaCl saline and HIUS application. For this purpose, a large HIUS radiating pen was introduced into the abdominal cavity and HIUS was applied on two of the four abdominal quadrants for 300 seconds each at an output power of 70 W, 50 % amplitude and 20 kHz frequency. Following the procedure, small intestinal tissue samples were retrieved for further analyses. Results: Peritoneal and subperitoneal layers showed structural changes only visible on a microscopic level. The peritoneal layer was transformed into a mesh-like structure while the subperitoneal layer (depth of 142 +/- 28 µm) exhibited microcavities and vascular detachment from surrounding tissues. No bowel rupture or vascular perforations were observed. Conclusions: Our data indicate that HIUS is a technically feasible and safe add-on procedure for intraperitoneal chemotherapy (IPC) with measurable microscopic changes on the peritoneal surface. Pretreatment of the abdominal cavity with HIUS could significantly improve IPC efficacy. Further studies are required to optimize and evaluate this novel approach.

Electrostatic Intraperitoneal Aerosol Delivery of Nanoparticles: Proof of Concept and Preclinical Validation

There is an increasing interest in intraperitoneal delivery of chemotherapy as an aerosol in patients with peritoneal metastasis. The currently used technology is hampered by inhomogenous drug delivery throughout the peritoneal cavity because of gravity, drag, and inertial impaction. Addition of an electrical force to aerosol particles, exerted by an electrostatic field, can improve spatial aerosol homogeneity and enhance tissue penetration. A computational fluid dynamics model shows that electrostatic precipitation (EP) results in a significantly improved aerosol distribution. Fluorescent nanoparticles (NPs) remain stable after nebulization in vitro, while EP significantly improves spatial homogeneity of NP distribution. Next, pressurized intraperitoneal chemotherapy with and without EP using NP albumin bound paclitaxel (Nab-PTX) in a novel rat model is examined. EP does not worsen the effects of CO₂ insufflation and intraperitoneal Nab-PTX on mesothelial structural integrity or the severity of peritoneal inflammation. Importantly, EP significantly enhances tissue penetration of Nab-PTX in the anatomical regions not facing the nozzle of the nebulizer. Also, the addition of EP leads to more homogenous peritoneal tissue concentrations of Nab-PTX, in parallel with higher plasma concentrations. In conclusion, EP enhances spatial homogeneity and tissue uptake after intraperitoneal nebulization of anticancer NPs.

Synergy between Intraperitoneal Aerosolization (PIPAC) and Cancer Nanomedicine: Cisplatin-Loaded Polyarginine-Hyaluronic Acid Nanocarriers Efficiently Eradicate Peritoneal Metastasis of Advanced Human Ovarian Cancer

Intra-abdominal dissemination of peritoneal nodules, a condition known as peritoneal carcinomatosis (PC), is typically diagnosed in ovarian cancer patients at the advanced stages. The current treatment of PC consists of perioperative systemic chemotherapy and cytoreductive surgery, followed by intra-abdominal flushing with solutions of chemotherapeutics such as cisplatin and oxaliplatin. In this study, we developed cisplatin-loaded polyarginine-hyaluronic acid nanoscale particles (Cis-pARG-HA NPs) with high colloidal stability, marked drug loading efficiency, unimpaired biological activity, and tumor-targeting ability. Injected Cis-pARG-HA NPs showed enhanced antitumor activity in a rat model of PC, compared to injection of the free cisplatin drug. The activity of Cis-pARG-HA NPs could even be further improved when administered by an intra-abdominal aerosol therapy, referred to as pressurized intraperitoneal aerosol chemotherapy (PIPAC). PIPAC is hypothesized to ensure a more homogeneous drug distribution together with a deeper drug penetration into peritoneal tumor nodules within the abdominal cavity. Using fluorescent pARG-HA NPs, this enhanced nanoparticle deposit on tumors could indeed be observed in regions opposite the aerosolization nozzle. Therefore, this study demonstrates that nanoparticles carrying chemotherapeutics can be synergistically combined with the PIPAC technique for IP therapy of disseminated advanced ovarian tumors, while this synergistic effect was not observed for the administration of free cisplatin.

The concept of foam as a drug carrier for intraperitoneal chemotherapy, feasibility, cytotoxicity and characteristics

For decades, intraperitoneal chemotherapy (IPC) was delivered into the abdominal cavity as a liquid solution. This preliminary study aims to evaluate foam as a potential new drug carrier for IPC delivery. Foam-based intraperitoneal chemotherapy (FBIC) was produced with taurolidine, hydrogen peroxide, human serum, potassium iodide and doxorubicin/ oxaliplatin for both ex vivo and in vitro experiments. Analysis of FBIC efficacy included evaluation of cytotoxicity, tissue penetration, foam stability, temperature changes and total foam volume per time evaluation. FBIC showed penetration rates of about 275 ± 87 µm and higher cytotoxicity compared to controls and to conventional liquid IPC (p < 0.005). The volume of the generated foam was approximately 50-times higher than the initial liquid solution and temporarily stable. Foam core temperature was measured and increased to 47 °C after 9 min. Foam ingredients (total protein content) were evenly distributed within different locations. Our preliminary results are quite encouraging and indicate that FBIC is a feasible approach. However, in order to discuss a possible superior effect over conventional liquid or aerosolized chemo applications, further studies are required to investigate pharmacologic, pharmacodynamic and physical properties of FBIC.

Comparison between microcatheter and nebulizer for generating Pressurized IntraPeritoneal Aerosol Chemotherapy (PIPAC)

Background

This study compares an endoscopic microcatheter and a nebulizer for delivering Pressurized IntraPeritoneal Aerosol Chemotherapy (PIPAC).

Methods

This is an in vitro and ex vivo study in an established model (inverted bovine urinary bladder). Four parameters were compared to determine the performance of a micro-perforated endoscopic spray catheter vs. state-of-the art, nozzle technology: (1) surface coverage and pattern with methylene blue on blotting paper at three different distances; (2) median aerodynamic diameter (MAD) of aerosol droplets with three different solutions (H₂O, Glc 5% and silicon oil); (3) depth of tissue penetration of doxorubicin (DOX) and (4) tissue concentration of cisplatin (CIS) and DOX using standard clinical solutions.

Results

The spray area covered by the microcatheter was larger (p < 0.001) but its pattern was inhomogenous than with the nozzle technology. We found that aerosol droplets were larger in the test group than in the control group for all three solutions tested. Median tissue penetration of DOX was lower (980 µm) with the microcatheter than with the nebulizer (1235 µm) and distribution was more heterogeneous ( = 0.003) with the microcatheter. The median tissue concentration of DOX and CIS was lower and concentration of DOX was more heterogeneous with the microcatheter (p = 0.002).

Conclusions

This investigation has revealed that microcatheter technology generates larger aerosol droplet size, less drug tissue penetration and lower drug tissue concentration than the current nozzle technology. In the absence of clinical studies, use of microcatheters for delivering PIPAC can not be recommended at this stage.

Pressurized intraperitoneal aerosol chemotherapy: a review of the introduction of a new surgical technology using the IDEAL framework

BACKGROUND

The IDEAL (Idea, Development, Evaluation, Assessment, Long-term study) framework is a scheme of investigation for innovative surgical therapeutic interventions. Pressurized intraperitoneal aerosol chemotherapy (PIPAC) is a procedure based on laparoscopy to deliver intraperitoneal chemotherapy for peritoneal metastases, introduced in 2011. The aim of this article was to review literature on PIPAC and assess whether development of the technique has followed the IDEAL framework.

METHODS

A search of MEDLINE and Embase was carried out to identify scientific reports on PIPAC published between January 2000 and February 2019. The studies were categorized according to the IDEAL stages.

RESULTS

Eighty-six original research papers on PIPAC were identified. There were 23 stage 0, 18 stage 1, 25 stage 2a and six stage 2b studies. Protocol papers for stage 1, 2b and 3 studies, and trial registrations for stage 2a studies, were also identified. The number of centres publishing reports and the number of publications has increased each year. Overall, there has been progression through the IDEAL stages; however, about 60 per cent of clinical reports published in 2018 were stage 1 Idea-type studies.

CONCLUSION

Since its introduction, studies investigating PIPAC have progressed in line with the IDEAL framework. However, the majority of studies reported recently were stage 0 and 1 studies.

Evaluation of a Novel Prototype for Pressurized Intraperitoneal Aerosol Chemotherapy

Pressurized intraperitoneal aerosol chemotherapy (PIPAC) has been suggested as an alternative option for treating peritoneal carcinomatosis (PC). Even with its clinical advantages, the current PIPAC system still suffers from limitations regarding drug distribution area and penetration depth. Thus, we evaluated the new PIPAC system using a novel prototype, and compared its performance to the results from previous studies related with the current MIP^® indirectly because the system is currently not available for purchase in the market. The developed prototype includes a syringe pump, a nozzle, and controllers. Drug distribution was conducted using a methylene blue solution for performance test. For penetration depth evaluation, an ex-vivo experiment was performed with porcine tissues in a 3.5 L plastic box. Doxorubicin was sprayed using the novel prototype, and its penetration depth was investigated by confocal laser scanning microscopy. The experiment was repeated with varying nozzle levels from the bottom. The novel prototype sprays approximately 30 μm drug droplets at a flow rate of 30 mL/min with 7 bars of pressure. The average diameter of sprayed region with concentrated dye was 18.5 ± 1.2 cm, which was comparable to that of the current MIP^® (about 10 cm). The depth of concentrated diffusion (DCD) did not differ among varying nozzle levels, whereas the depth of maximal diffusion (DMD) decreased with increasing distance between the prototype and the bottom (mean values, 515.3 μm at 2 cm; 437.6 μm at 4 cm; 363.2 μm at 8 cm), which was comparable to those of the current MIP^® (about 350–500 μm). We developed a novel prototype that generate small droplets for drug aerosolization and that have a comparably wide sprayed area and depth of penetration to the current MIP^® at a lower pressure.

Intrathoracic aerosol chemotherapy via spray-catheter

Pressurized intrathoracic aerosol chemotherapy (PITAC) has been introduced to the clinical setting as a novel treatment option for pleural metastasis (PM). For decades the therapeutic application of aerosols was limited to intrabronchial delivery. However, present studies suggest performing PITAC on patients with PM and malignant pleural effusion. Using an established ex vivo swine model, the present study aimed to introduce a facilitated intrathoracic chemoaerosol application via spray-catheter. Using an ex-vivo model of 3 postmortem swine, the feasibility of intrathoracic aerosol chemotherapy (ITC) with doxorubicin using a spray-catheter was evaluated in a normal pressure environment. Following thoracotomy, the spray-catheter was inserted via trocar. Tissue samples were retrieved and further analyzed by fluorescence microscopy to detect doxorubicin contact. Our data demonstrated that the application of ITC was technically feasible and did not exhibit any significant obstacles. By making a minimally invasive thoracotomy incision it was possible to create an adequate pneumothorax without the need of a double-lumen tube or intubation. ITC did not require the creation of a pressurized environment. Tissue samples revealed doxorubicin contact within the pleura. In conclusion, ITC is a fast and feasible procedure that could possibly be administered via bedside application, therefore eliminating the need of an operating room and surgical staff. However, further studies are required to evaluate the safety of patients and physicians regarding this novel applicational modality. Nevertheless, the present study demonstrated that ITC may potentially be applied at bedside, an option that is particularly important for patients who do not qualify for PITAC procedures.

Pressurized Intraperitoneal Aerosol Chemotherapy, a Palliative Treatment Approach for Patients With Peritoneal Carcinomatosis: Description of Method and Systematic Review of Literature

BACKGROUND

Peritoneal metastases arise in patients with a variety of primary cancers, and are associated with a poor prognosis. Systemic chemotherapy is the mainstay of treatment; however, the morbidity is considerable and the survival benefit is modest. Cytoreductive surgery and heated intraperitoneal chemotherapy is a potentially curative treatment available to a minority of patients; however, most develop recurrent disease. A novel palliative treatment for peritoneal metastases, pressurized intraperitoneal aerosol chemotherapy, has recently been introduced. Pressurized intraperitoneal aerosol chemotherapy utilizes an aerosol of chemotherapy in carbon dioxide gas. It is instilled into the abdomen under pressure via laparoscopic ports. No cytoreduction is performed. Pressurized intraperitoneal aerosol chemotherapy can be repeated at 6-week intervals. Oxaliplatin or cis-platinum and doxorubicin have been used to date.

OBJECTIVE

This study aims to systematically review and evaluate the method, and the preclinical and early clinical results of pressurized intraperitoneal aerosol chemotherapy.

DATA SOURCES

Medline and the Cochrane Library were the data sources for the study.

STUDY SELECTION

Peer-reviewed series of greater than 10 patients, with sufficient patient data, through April 2019, were selected.

INTERVENTION

Patients with peritoneal metastases underwent pressurized intraperitoneal aerosol chemotherapy.

MAIN OUTCOME MEASURES

Patient dropout, histologic tumor response, adverse events, and 30-day mortality were the primary outcomes measured.

RESULTS

A total of 921 patients with peritoneal metastases were brought to the operating room for pressurized intraperitoneal aerosol chemotherapy. The number of pressurized intraperitoneal aerosol chemotherapy treatments administered was as follows: 1 treatment, 862 (94%); 2 treatments, 645 (70%); and 3 treatments, 390 patients (42%). Initial laparoscopic access was not possible in 59 patients (6.4%). Common Terminology Criteria for Adverse Events grade 3 or higher were noted in 13.7% of the patients who, collectively, underwent a total of 2116 treatments. The 30-day mortality was 2.4% (22/921).

LIMITATIONS

This study was limited by the heterogeneity of reported data and primary tumor types and by the lack of long-term survival data.

CONCLUSIONS

Early clinical results are encouraging, but tumor-specific, prospective, randomized trials are needed to compare pressurized intraperitoneal aerosol chemotherapy to systemic chemotherapy. This method has yet to be introduced to the United States. It is another therapeutic option for patients with peritoneal metastases and will broaden the patient base for future clinical trials.

Creating nanocrystallized chemotherapy: the differences in pressurized aerosol chemotherapy (PAC) via intracavitary (IAG) and extracavitary aerosol generation (EAG) regarding particle generation, morphology and structure

Background: Nanocrystallization is a promising field for the development of new drugs. This study aims to present the use of nanocrystallization via intraperitoneal nanoaerosol therapy (INAT) for the treatment of peritoneal metastases.

Methods: A continuous aerosol generation device was used to aerosolize a highly concentrated doxorubicin solution within a dry CO₂ environment. The produced nanoaerosol was directed into an ex vivo abdominal model and collision of aerosol particles with placed samples was subject to further analysis via scanning-electron microscopy (SEM). SEM detected structural changes of particles caused by migration to different locations.

Results: It was possible to visualize the contact of doxorubicin aerosol particles with the surface. Larger particles as well as particles closer to the aerosol generation chamber collided with the glass sample creating liquid drops, while smaller particles with more distance to the aerosol chamber collided as highly concentrated nanocrystals. The amount of nanocrystal particles outweighed the amount of fluid aerosol particles by far.

Conclusions: Under optimal conditions, the formation of nanocrystals via aerosol creation device is possible. While a wide range of possible applications of nanocrystals is conceivable, surface coating with drug particles is especially interesting as it may serve as an alternative to conventional liquid intraperitoneal chemotherapy. Further studies are required to investigate nanocrystallization of chemotherapeutic solutions as well as its physical and pharmacological properties and side effects.

Overcoming Drug Resistance by Taking Advantage of Physical Principles: Pressurized Intraperitoneal Aerosol Chemotherapy (PIPAC)

Theoretical considerations as well as comprehensive preclinical and clinical data suggest that optimizing physical parameters of intraperitoneal drug delivery might help to circumvent initial or acquired resistance of peritoneal metastasis (PM) to chemotherapy. Pressurized Intraperitoneal Aerosol Chemotherapy (PIPAC) is a novel minimally invasive drug delivery system systematically addressing the current limitations of intraperitoneal chemotherapy. The rationale behind PIPAC is: (1) optimizing homogeneity of drug distribution by applying an aerosol rather than a liquid solution; (2) applying increased intraperitoneal hydrostatic pressure to counteract elevated intratumoral interstitial fluid pressure; (3) limiting blood outflow during drug application; (4) steering environmental parameters (temperature, pH, electrostatic charge etc.) in the peritoneal cavity for best tissue target effect. In addition, PIPAC allows repeated application and objective assessment of tumor response by comparing biopsies between chemotherapy cycles. Although incompletely understood, the reasons that allow PIPAC to overcome established chemoresistance are probably linked to local dose intensification. All pharmacological data published so far show a superior therapeutic ratio (tissue concentration/dose applied) of PIPAC vs. systemic administration, of PIPAC vs. intraperitoneal liquid chemotherapy, of PIPAC vs. Hyperthermic Intraperitoneal Chemotherapy (HIPEC) or PIPAC vs. laparoscopic HIPEC. In the initial introduction phase, PIPAC has been used in patients who were quite ill and had already failed multiple treatment regimes, but it may not be limited to that group of patients in the future. Rapid diffusion of PIPAC in clinical practice worldwide supports its potential to become a game changer in the treatment of chemoresistant isolated PM of various origins.

Increased Tissue Penetration of Doxorubicin in Pressurized Intraperitoneal Aerosol Chemotherapy (PIPAC) after High-Intensity Ultrasound (HIUS)

BACKGROUND

High-intensity ultrasound (HIUS) has been studied for the past two decades as a new therapeutic option for solid tumor direct treatment and a method for better chemotherapy delivery and perfusion. This treatment approach has not been tested to our knowledge in peritoneal metastatic therapy, where limited tissue penetration of intraperitoneal chemotherapy has been a main problem. Both liquid instillations and pressurized aerosols are affected by this limitation. This study was performed to evaluate whether HIUS improves chemotherapy penetration rates.

METHODS

High-intensity ultrasound (HIUS) was applied for 0, 5, 30, 60, 120, and 300 seconds on the peritoneal tissue samples from fresh postmortem swine. Samples were then treated with doxorubicin via pressurized intraperitoneal aerosol chemotherapy (PIPAC) under 12 mmHg and 37°C temperature. Tissue penetration of doxorubicin was measured using fluorescence microscopy on frozen thin sections.

RESULTS

Macroscopic structural changes, identified by swelling of the superficial layer of the peritoneal surface, were observed after 120 seconds of HIUS. Maximum doxorubicin penetration was significantly higher in peritoneum treated with HIUS for 300 seconds, with a depth of 962.88 ± 161.4 μm (p < 0.05). Samples without HIUS had a penetration depth of 252.25 ± 60.41. Tissue penetration was significantly increased with longer HIUS duration, with up to 3.8-fold increased penetration after 300 sec of HIUS treatment.

CONCLUSION

Our data indicate that HIUS may be used as a method to prepare the peritoneal tissue for intraperitoneal chemotherapy. Higher tissue penetration rates can be achieved without increasing chemotherapy concentrations and preventing structural damage to tissue using short time intervals. More studies need to be performed to analyze the effect of HIUS in combination with intraperitoneal chemotherapy.

Release of doxorubicin from its liposomal coating via high intensity ultrasound

The present ex vivo study was performed to analyze the impact of high intensity ultrasound (HIUS) on penetration depth and particle stability of liposomal doxorubicin (LD) on the peritoneal surface. Fresh post mortem swine peritoneum was cut into proportional sections and subjected to a previously established ex vivo model of pressurized intraperitoneal aerosol chemotherapy (PIPAC). Samples were treated with 50 ml NaCl (0.9%) containing 3 mg LD via PIPAC or lavage. In both groups, half of the samples received additional HIUS treatment. Samples treated via PIPAC were covered with a 30-mm-thick abdominal muscle wall tissue, fatty tissue and skin, followed by transcutaneous HIUS. Samples administered with LD via lavage received close-range contact HIUS. Doxorubicin tissue penetration was measured using fluorescence microscopy on frozen sections. Liposomal integrity on peritoneal surfaces was measured via electron microscopy (EM). Mean penetration rates of doxorubicin were significantly higher with HIUS in combination with PIPAC or lavage compared with PIPAC alone (P<0.001) or lavage alone (P<0.00001). LD was not detected on the peritoneal surface via EM analysis in either group following HIUS. The present data suggested that HIUS may be a feasible application that can facilitate the release of doxorubicin from its liposomal envelope. HIUS was effective in both close-range, in contact with the samples, and through the abdominal wall. The present approach may be used in the future for both endoscopic and open lavage of the peritoneal cavity with LD in intraperitoneal chemotherapeutic applications such as hyperthermic intraperitoneal chemotherapy or PIPAC.

A real-time ex vivo model (eIBUB) for optimizing intraperitoneal drug delivery as an alternative to living animal models

BACKGROUND

Optimization of intraperitoneal drug delivery systems requires functional models. We proposed the Inverted Bovine Urinary Bladder Model (IBUB), but IBUB does not allow repeated measurements over time and there is a significant biological variability between organs.

METHODS

A further development of IBUB is presented, based on the physical principle of communicating vessels. Fresh bovine bladders were inverted so that the peritoneum lines up the inner surface. The IBUB and a second vessel were then interconnected under the same CO2 pressure and placed on two scales. The therapeutic solution (Doxorubicin 2.7 mg and Cisplatin 13.5 mg) was delivered via an aerosolizer. All experiments were in triplicate and blinded to the origin of samples, measurements in a GLP-certified laboratory.

RESULTS

The enhanced IBUB (eIBUB) model allows measurements of tissue drug concentration, depth of tissue penetration and spatial distribution. The homogeneous morphology of the peritoneum enables standardized, multiple tissue sampling. eIBUB minimizes biological variability between different bladders and eliminates the bias caused by the liquid collecting at the bottom of the model. Concentration of doxorubicin in the eIBUB (mean ± STDV: 18.5 ± 22.6 ng/mg) were comparable to clinical peritoneal biopsies (19.2 ± 38.6 ng/mg), as was depth of drug penetration (eIBUB: mean (min-max) 433 (381-486) µm, clinical ~ 500 µm).

CONCLUSIONS

The eIBUB model is a simple and powerful ex vivo model for optimizing intraperitoneal drug delivery and represents an attractive alternative to animal models. Results obtained are similar to those obtained in the human patient.

Assessment of the aerosol distribution pattern of a single-port device for intraperitoneal administration of therapeutic substances

BACKGROUND

In the last 20 years, intraperitoneal chemotherapy (IPC) has been explored as a modality for the management of peritoneal metastases of gynecologic, gastrointestinal, and primary peritoneal tumors. Direct delivery of chemotherapeutic agents to the peritoneal cavity space has proved superior to systemic chemotherapy when evaluating characteristics such as drug concentration reached in the peritoneal space, penetration into peritoneal metastases, and chemotherapy-related toxicity. Traditionally, IPC is delivered by peritoneal lavage with a liquid solution. This form of delivery has limitations, including inhomogeneous intraperitoneal distribution and limited ability to penetrate tissues and metastatic nodules. An alternative mode of delivery is so-called pressurized intraperitoneal aerosol chemotherapy (PIPAC). Within this context, the present study sought to identify the pattern of spatial distribution of therapeutic solutions aerosolized into the peritoneal space using a single-port PIPAC device and ascertain whether the aerosolized method is superior to the traditional (liquid) mode of IPC delivery.

METHODS

Analysis of the rate of intra-abdominal staining with aerosolized 2% silver nitrate in five porcine models.

RESULTS

Assessment of differences in stain impregnation between the upper, middle, and lower abdomen did not reveal significant differences (p = 0.42). The median sum scores were 1 for the upper abdomen and 3 for the middle and lower abdomen.

CONCLUSIONS

Aerosolization does not reach all regions of the abdomen homogeneously. However, adequate exposure of the upper abdomen, mid-abdomen, and lower abdomen to chemotherapeutic agents can be achieved with PIPAC.

Aerosolization of Nanotherapeutics as a Newly Emerging Treatment Regimen for Peritoneal Carcinomatosis

Recent advances in locoregional chemotherapy have opened the door to new approaches for the clinical management of peritoneal carcinomatosis (PC) by facilitating the delivery of anti-neoplastic agents directly to the tumor site, while mitigating adverse effects typically associated with systemic administration. In particular, an innovative intra-abdominal chemotherapeutic approach, known as Pressurized Intraperitoneal Aerosol Chemotherapy (PIPAC), was recently introduced to the intraperitoneal (IP) therapy regimens as a palliative therapeutic option in patients with PC, presumably providing a better drug distribution pattern together with deeper drug penetration into tumor nodules within the peritoneal space. Furthermore, the progress of nanotechnology in the past few decades has prompted the application of different nanomaterials in IP cancer therapy, offering new possibilities in this field ranging from an extended retention time to sustained drug release in the peritoneal cavity. This review highlights the progress, challenges, and opportunities in utilizing cancer nanotherapeutics for locoregional drug delivery, with a special emphasis on the aerosolization approach for intraperitoneal therapies.

Comparing the cytotoxicity of taurolidine, mitomycin C, and oxaliplatin on the proliferation of in vitro colon carcinoma cells following pressurized intra-peritoneal aerosol chemotherapy (PIPAC)

BACKGROUND

Besides its known antibacterial effect commonly used in intraperitoneal lavage, taurolidine has been observed to possess antineoplastic properties. In order to analyse this antineoplastic potential in a palliative therapeutic setting, taurolidine (TN) was compared to mitomycin C (MMC) and oxaliplatin (OX), known antineoplastic agents which are routinely used in intraperitoneal applications, following pressurized intra-peritoneal aerosol chemotherapy (PIPAC).

METHODS

An in vitro model was established using a colon adenocarcinoma cell line (HT-29 human cells). Different experimental dosages of TN and combinations of TN, MMC, and OX were applied via PIPAC. To measure cell proliferation, a colorimetric tetrazolium reduction assay was utilized 24 h after PIPAC.

RESULTS

We demonstrated a cytotoxic effect of TN and OX (184 mg/150 mL, p < 0.01) on tumor cell growth. An increasing dosage of TN (from 0.5 g/100 mL to 0.75 g/150 mL) correlated with higher cell toxicity when compared to untreated cells (p < 0.05 and p < 0.01, respectively). PIPAC with OX and both OX and TN (0.5 g/100 mL) showed the same cytotoxic effect (p < 0.01). No significant impact was observed for MMC (14 mg/50 mL, p > 0.05) or MMC with OX (p > 0.05) applied via PIPAC.

CONCLUSIONS

The intraperitoneal application of TN is mostly limited to lavage procedures in cases of peritonitis. Our results indicate a substantial antineoplastic in vitro effect on colon carcinoma cells following PIPAC application. While this effect could be used in the palliative treatment of peritoneal metastases, further clinical studies are required to investigate the feasibility of TN application in such cases.

Particle stability and structure on the peritoneal surface in pressurized intra-peritoneal aerosol chemotherapy (PIPAC) analysed by electron microscopy: First evidence of a new physical concept for PIPAC

Pressurized intra-peritoneal aerosol chemotherapy (PIPAC) has been introduced to the clinical setting as a novel approach for the treatment of peritoneal metastasis. The local interaction of chemoaerosol droplets with the peritoneal surface as well as their distribution pattern is considered the main advantage over conventional liquid intraperitoneal chemotherapy. The aim of the present study was to investigate the behavior of these aerosol particles during PIPAC application via electron microscopy. Solutions of doxycycline, liposomal doxorubicin and macrophage cells were aerosolized using an established ex-vivo model. PIPAC was performed on peritoneum samples via microcatheter (MC) at a pressure of 12 mmHg C02 at 27°C. Following PIPAC the surface structure of applied particles was measured via electron microscopy. The aerosol particle contact of doxycyclin created a nanofilm of ~200 nm height on the peritoneal surface, and this height was revealed to be independent of the size of the initial particle hitting. These nanofilm blocks of 'cylinders' are of different diameters depending on the initial aerosol particle hitting that spot. Diameters of these 'cylinders' are far wider than the original diameter of the initial aerosol particle. However, coated particles such as liposomal doxorubicin and macrophages remained intact following contact with the peritoneal surface. Based on this and other data, the concept that aerosol particles exhibit a gas-like behavior in the abdomen creating a therapeutic capnoperitoneum should be revised. Fluid aerosol particles collide with the peritoneum creating a nanofilm. The interaction of pressurized intraperitoneal aerosol on the peritoneum is therefore closer to the distribution of a liquid film than to that of a gas. Further studies are required to further analyze the interaction of this nanofilm on the peritoneum.

Feasibility and Characteristics of Pressurized Aerosol Chemotherapy (PAC) in the Bladder as a Therapeutical Option in Early-stage Urinary Bladder Cancer

BACKGROUND

Pressurized aerosol chemotherapy (PAC) is a novel approach to the treatment of surface malignancies. This study aimed to investigate whether PAC is a feasible treatment of early-stage bladder cancer.

MATERIALS AND METHODS

PAC via inserted microcatheter was performed on a fresh urinary bladder in a post-mortem swine model (n=3), creating a pressurized doxorubicin chemoaerosol. Drug penetration of aerosolized doxorubicin at different concentrations (3 mg/50 ml, 9 mg/50 ml and 15 mg/50 ml) and different locations on the mucosa was measured via fluorescence microscopy.

RESULTS

Mean endoluminal penetration rates for the urothelium following PAC reached 149±61 μm (using 15 mg/50 ml). Doxorubicin penetration was significantly increased with higher drug concentration (15 vs. 3 mg/50 ml: p<0.01). This study demonstrated the feasibility of PAC for intravesical use.

CONCLUSION

PAC is a feasible minimally-invasive approach to the treatment of early-stage bladder cancer.

Effect of Liposomal Doxorubicin in Pressurized Intra-Peritoneal Aerosol Chemotherapy (PIPAC)

Background: This ex-vivo study was performed to compare the impact of doxorubicin vs. liposomal doxorubicin on penetration depth in peritoneal tissue during Pressurized Intra-Peritoneal Aerosol Chemotherapy (PIPAC) via microcatheter (MC). Methods: Fresh post mortem swine peritoneum was cut into proportional sections. One group of samples was treated with PIPAC with Doxorubicin (D), and the other was treated with PIPAC with liposomal doxorubicin (LD). Tissue specimens were placed as follows: at the bottom of the plastic box (1), at the side wall (2), at the top cover (3) and the side of the box covered by a plastic tunnel (4). In-tissue doxorubicin penetration was measured using fluorescence microscopy on frozen thin sections. Results: Medium penetration levels with D were 325 µm (1), 152 µm (2), 84 µm (3) and 71 µm (4), respectively. Medium penetration levels with LD were significantly lower with 10 µm (1), 2 µm (2), 0 µm (3) and 0 µm (4), respectively. In most samples that were treated with LD no doxorubicin could be detected at all. Conclusion: Our data indicate that liposomal coating of doxorubicin and possibly other chemotherapeutical drugs might inhibit their interaction with the peritoneal surface. This inhibition appears to be relatively strong, since doxorubicin is partially undetectable due to liposomal coating. Further studies are warranted to investigate this interaction and its potential benefit in peritoneal applications.

Pressurized intraperitoneal aerosol chemotherapy (PIPAC) for peritoneal carcinomatosis: systematic review of clinical and experimental evidence with special emphasis on ovarian cancer

BACKGROUND

Systemic chemotherapy is not effective in patients with peritoneal carcinomatosis (PC) and only a minority of affected patients is eligible for cytoreductive surgery. Intraperitoneal chemotherapy may provide a therapy alternative for these patients.

METHODS

We performed a systematic review of clinical and experimental evidence on the safety and efficacy of pressurized intraperitoneal aerosol chemotherapy (PIPAC) in patients with PC and provide clinical recommendations based on the available evidence.

RESULTS

Fifty-eight reports were identified, categorized as experimental (18 reports), clinical (28 reports), and other articles (14 reports). Experimental studies demonstrated improved tissue penetration and peritoneal coverage. The 28 clinical studies reported on 3515 procedures in 1547 patients with PC of various primary tumors with 16 of these studies reporting on patients with ovarian cancer. Toxicity was manageable. Based on 1197 patients in 22 studies, adverse events CTCAE grades 1, 2, 3, 4, and 5 were observed in 537 (45%), 167 (14%), 83 (7%), 10 (0.8%), and 19 (1.6%) cases, respectively. In a pooled analysis, the objective tumor response rate was 69% and the mean overall survival duration was 13.7 months. No significant hepatic, renal, or hematologic toxicity was described. PIPAC maintained and/or improved quality of life, as reported in 10 studies with 396 patients.

CONCLUSIONS

Available evidence from controlled trials (phase I and phase II) and retrospective cohort studies in > 1500 patients unequivocally demonstrates that PIPAC is feasible, safe, and effective. PIPAC maintains quality of life in patients with recurrent cancer and PC. PIPAC is as evidence-based as any other treatment in women with ovarian cancer and PC beyond the third line of systemic chemotherapy and can be recommended in this indication.

Prospective, single-center implementation and response evaluation of pressurized intraperitoneal aerosol chemotherapy (PIPAC) for peritoneal metastasis

BACKGROUND

Pressurized intraperitoneal aerosol chemotherapy (PIPAC) is a laparoscopy-guided administration of aerosolized chemotherapy. PIPAC seems to improve objective tumor response, survival and quality of life in patients with peritoneal metastasis. We assessed feasibility and efficacy of PIPAC in patients with peritoneal metastasis (PM).

METHODS

Patients were included in a prospective PIPAC protocol. Patients with colorectal PM were treated with oxaliplatin, patients with other primary tumors were treated with cisplatin and doxorubicin. Any chemotherapy exposure for healthcare workers was monitored by environmental and biological sampling. Feasibility was quantified by completion and complication rates. Response evaluation was documented by the peritoneal regression grading score (PRGS) and by peritoneal lavage cytology. Biopsy sites were marked by clips. Quality of life questionnaires were collected at baseline and after 60, 120 and 180 days.

RESULTS

A total of 35 patients with PM were treated with a median of three PIPAC procedures (range 1-9). Intraperitoneal access and completion of PIPAC was achieved in all patients. Few complications and adverse events were noted. There was no risk of chemotherapy exposure for healthcare workers. The mean PRGS was reduced significantly and a reduction of the PRGS was seen in 67% of the patients. Conversion from positive to negative cytology was achieved in 23% of the patients. Quality of life was stabilized from baseline to day 60.

CONCLUSIONS

PIPAC is feasible and well tolerated, may stabilize the quality of life in patients with end-stage PM and may induce histological and cytological regression.This study is registered at www.clinicaltrials.gov [ClinicalTrials.gov identifier: NCT02320448].

Pressurized IntraPeritoneal Aerosol Chemotherapy (PIPAC) for the treatment of malignant mesothelioma

Background

Patients with recurrent malignant epithelioid mesothelioma (MM) after surgery and standard chemotherapy with cisplatin and pemetrexed have limited treatment options.

Methods

We performed a retrospective cohort study of patients with recurrent MM undergoing Pressurized IntraPeritoneal/Thoracal Aerosol Chemotherapy (PIPAC/PITAC) with doxorubicin 1.5 mg/m² and cisplatin 7.5 mg/m². Data were retrospectively collected in a prospective registry of patients undergoing PIPAC/PITAC. Study outcomes were microscopic tumor regression grade (TRG), survival and adverse events (v4.0 CTCAE).

Results

A total of 29 patients (m/f = 17/12) with MM with a mean age of 62.4 (range: 42 to 84) years were analyzed. A total of 74 PIPAC and 5 PITAC procedures were performed. The mean number of PIPAC applications was 2.5 (range: 0 to 10) per patient. Twenty patients (69%) had > 2 PIPAC procedure and were eligible for TRG analysis. TRG 1 to 4 was observed in 75% (15/20) of patients. Major regression (TRG 3) or complete regression (TRG 4) was observed in 20% and 10%, respectively. PIPAC induced significant tumor regression in 51.7% (15/29) of patients with a cumulative effect after repetitive PIPACs (PIPAC #1 vs. PIPAC #2: p = 0.001; PIPAC #1 vs. PIPAC #3: p = 0.001; PIPAC #1 vs. PIPAC #4: p = 0.001). Postoperative CTCAE grade 4 complications were observed in two patients (6.9%) who had cytoreductive surgery (CC2) and intraoperative PIPAC. One patient (3.4%) died due to postoperative kidney insufficiency. After a follow up of 14.4 (95% CI: 8.1 to 20.7) months after the last PIPAC/PITAC application, median overall survival was 26.6 (95% CI: 9.5 to 43.7) months (from the first application).

Conclusion

After prior abdominal surgery and systemic chemotherapy, repetitive PIPAC applications are feasible and safe for patients with end-stage MM. Furthermore, PIPAC induces significant histological regression of malignant mesothelioma in the majority of patients. PITAC is feasible, but its safety and efficacy to control malignant pleural effusion remain unclear.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4363-0) contains supplementary material, which is available to authorized users.

Hyperthermic intracavitary nanoaerosol therapy (HINAT) as an improved approach for pressurised intraperitoneal aerosol chemotherapy (PIPAC): Technical description, experimental validation and first proof of concept

Background: The delivery of aerosolised chemotherapeutic substances into pressurised capnoperitonea has been reported to be more effective than conventional liquid chemotherapy for the treatment of peritoneal carcinomatosis. However, recent reports reveal limitations of the currently available technology. Material and Methods: A novel approach for pressurised intraperitoneal aerosol chemotherapy (PIPAC), called hyperthermic intracavitary nanoaerosol therapy (HINAT), based on extracavitary generation of hyperthermic and unipolar charged aerosols, was developed. The aerosol size distribution, the spatial drug distribution and in-tissue depth penetration of HINAT were studied by laser diffraction spectrometry, differential electrical mobility analysis, time of flight spectrometry, scintigraphic peritoneography and fluorescence microscopy. All experiments were performed contemporaneous with conventional PIPAC for the purpose of comparison. Furthermore, a first proof of concept was simulated in anesthetised German Landrace pigs. Results: HINAT provides a nanometre-sized (63 nm) unipolar-charged hyperthermic (41 °C) drug aerosol for quasi uniform drug deposition over the whole peritoneum with significantly deeper drug penetration than that offered by conventional PIPAC.

Scintigraphic peritoneography reveals a non-uniform 99mTc-Pertechnetat aerosol distribution pattern for Pressurized Intra-Peritoneal Aerosol Chemotherapy (PIPAC) in a swine model

BACKGROUND

Although recent data are contradictory, it is still claimed that Pressurized Intra-Peritoneal Aerosol Chemotherapy (PIPAC) would deliver an aerosol which distributes homogeneously throughout the entire abdominal cavity.

METHODS

^99mTc-Pertechnetat was administered in four postmortem swine using either PIPAC or liquid intra-peritoneal chemotherapy (IPC). The animals were examined by planar scintigraphy and SPECT/CT. Planar distribution images were divided into four regions of interest (ROIs: right/left upper and lower abdominal quadrant). SPECT/CT slices were scanned for areas of intense nuclide accumulation ("hot spots"). The percentage of relative distribution for planar scintigraphy was calculated by dividing the summed individual counts of each ROI by total counts measured in the entire abdominal cavity. The relative distribution of the "hot spots" was analyzed by dividing the counts of the local volume of interest (VOI) by the summed volume counts measured in the entire abdominal cavity.

RESULTS

In all four animals, planar scintigraphy showed inhomogeneous nuclide distribution. After PIPAC only 8-10% of the delivered nuclide was detected in one ROI with a mean deviation of 40% and 74% from a uniform nuclide distribution pattern. In all animals, SPECT/CT revealed "hot spots" beneath the PIPAC Micropump, catheter tip, and in the cul-de-sac region which comprise about 25% of the total amount of delivered nuclide in 2.5% of the volume of the entire abdominal cavity.

CONCLUSIONS

Our present data indicate that the intra-abdominal aerosol distribution pattern of PIPAC therapy is non-homogeneous and that the currently applied technology has still not overcome the problem of inhomogeneous drug distribution of IPC.

Systematic review of pressurized intraperitoneal aerosol chemotherapy for the treatment of advanced peritoneal carcinomatosis

BACKGROUND

Pressurized intraperitoneal aerosol chemotherapy (PIPAC) is a minimally invasive approach under investigation as a novel treatment for patients with peritoneal carcinomatosis of various origins. The aim was to review the available evidence on mechanisms, clinical effects and risks.

METHODS

This was a systematic review of the literature on pressurized intraperitoneal chemotherapy published between January 2000 and October 2016. All types of scientific report were included.

RESULTS

Twenty-nine relevant papers were identified; 16 were preclinical studies and 13 were clinical reports. The overall quality of the clinical studies was modest; five studies were prospective and there was no randomized trial. Preclinical data suggested better distribution and higher tissue concentrations of chemotherapy agents in PIPAC compared with conventional intraperitoneal chemotherapy by lavage. Regarding technical feasibility, laparoscopic access and repeatability rates were 83-100 and 38-82 per cent. Surgery-related complications occurred in up to 12 per cent. Postoperative morbidity was low (Common Terminology Criteria for Adverse Events grade 3-5 events reported in 0-37 per cent), and hospital stay was about 3 days. No negative impact on quality of life was reported. Histological response rates for therapy-resistant carcinomatosis of ovarian, colorectal and gastric origin were 62-88, 71-86 and 70-100 per cent respectively.

CONCLUSION

PIPAC is feasible, safe and well tolerated. Preliminary good response rates call for prospective analysis of oncological efficacy.

A new ex vivo model for optimizing distribution of therapeutic aerosols: the (inverted) bovine urinary bladder

Background

Development of Pressurized IntraPeritoneal Aerosol Chemotherapy (PIPAC) requires adequate preclinical models.

Methods

The model should be easy to use, reproducible and cost-effective. It should have a volume similar to the human abdominal cavity, and an oval shape. The inner surface should be lined with serosa. The model should allow pharmacological and biological analysis, including histology. No living animals should be used.

Results

The fresh urinary bladder is explanted from an adult bovine in the slaughterhouse. A 4-cm incision is performed into the bladder neck. The bladder can be inverted through the incision, which allows exposition of the serosa on its inner side. A balloon trocar is inserted through the incision and a ligature placed, ensuring full tightness. The therapeutic capnoperitoneum is installed. The bovine bladder has a volume somewhat smaller (2-3 L) than the human abdominal cavity (3-5 L). Costs are minimal. There is no significant bacteriological contamination. Manipulation is simple.

Conclusions

The (inverted) bovine urinary bladder is an innovative and versatile ex vivo model for optimizing drug delivery with therapeutic aerosols both onto the mucosa or the serosa. This model can be used for pharmaceutical Quality-by-Design approaches and will replace a large number of experiments in the animal.

Cytotoxic effect of different treatment parameters in pressurized intraperitoneal aerosol chemotherapy (PIPAC) on the in vitro proliferation of human colonic cancer cells

Background

Pressurized intraperitoneal aerosol chemotherapy (PIPAC) has been recently reported as a new approach for intraperitoneal chemotherapy (IPC). By means of a patented micropump, the liquid chemotherapy is delivered into the peritoneal cavity as an aerosol which is supposed to achieve “gas-like” distribution. However, recent data report that the fraction of the submicron aerosol (gas-like) is less than 3 vol% of the total amount of aerosolized chemotherapy. Until today, possible modifications of treatment parameters during PIPAC with the aim of improving therapeutic outcomes have not been studied yet.

This study aims to establish an in vitro PIPAC model to explore the cytotoxic effect of the submicron aerosol fraction and to investigate the impact of different application parameters on the cytotoxic effect of PIPAC on human colonic cancer cells.

Methods

An in vitro model using HCT8 colon adenocarcinoma wild-type cells (HCT8^WT) and multi-chemotherapy refractory subline (HCT8^RT) was established. Different experimental parameters such as pressure, drug dosage, time exposure, and system temperature were monitored in order to search for the conditions with a higher impact on cell toxicity. Cell proliferation was determined by means of colorimetric MTT assay 48 h following PIPAC exposures.

Results

Standard operational parameters applied for PIPAC therapy depicted a cytotoxic effect of the submicron aerosol fraction generated by the PIPAC micropump. We also observed that increasing pressure significantly enhanced tumor cell toxicity in both wild-type and chemotherapy-resistant cells. A maximum of cytotoxicity was observed at 15 mmHg. Pressure >15 mmHg did not show additional cytotoxic effect on cells. Increased oxaliplatin dosage resulted in progressively higher cell toxicity as expected. However, in resistant cells, a significant effect was only found at higher drug concentrations. Neither an extension of exposure time nor an increase in temperature of the aerosolized chemotherapy solution added an improvement in cytotoxicity.

Conclusions

In this in vitro PIPAC model, the gas-like PIPAC aerosol fraction showed a cytotoxic effect which was enhanced by higher intra-abdominal pressure with a maximum at 15 mmHg. Similar findings were observed for drug dose escalation. A phase I dose escalation study is currently performed at our institution. However, increasing the intra-abdominal pressure might be a first and simple way to enhance the cytotoxic effect of PIPAC therapy which needs further clinical investigations.

Electronic supplementary material

The online version of this article (doi:10.1186/s12957-017-1109-4) contains supplementary material, which is available to authorized users.

Pharmacokinetic problems in peritoneal drug administration: an update after 20 years

Intraperitoneal chemotherapy has demonstrated significant pharmacologic and clinical advantage over traditional intravenous administration for cancers that are restricted to the peritoneal cavity. The combination of cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (HIPEC) has become the standard technique used to fight ovarian and gastrointestinal cancers in many centers. However, challenges remain for HIPEC to contact the entire peritoneal surface, penetrate the tumor tissue, and transport to the lymphatics and other metastatic sites. New innovations in delivery technique, such as heated aerosol, and in delivery molecules, such as microparticles, nanoparticles, nanogels, and tumor-penetrating peptides are being tested in animal models and will likely soon be in human trials. Improvements in overall care, such as the recent clinical trial of an oral agent for maintenance therapy in ovarian carcinoma, will continue in this field for the next 20 years.

Technical description of the microinjection pump (MIP®) and granulometric characterization of the aerosol applied for pressurized intraperitoneal aerosol chemotherapy (PIPAC)

BACKGROUND

Pressurized intraperitoneal aerosol chemotherapy (PIPAC) is gaining acceptance in clinical practice, but detailed information about the microinjection pump (MIP^®), the generated aerosol and drug distribution is missing.

ANALYTICAL METHODS

Ex vivo granulometric analyses by means of laser diffraction spectrometry were performed for MIP^® aerosol characterization. Beside the standard operation conditions, the impact of the volumetric liquid flow rate on the aerosol characteristics was investigated with different liquids. Granulometric results as well as the local drug distribution were verified by ex vivo gravimetric analyses. On the basis of determined MIP^® characteristics, the aerosol droplet size, which is necessary for a homogenous intra-abdominal drug distribution, was calculated.

RESULTS

Granulometric analyses showed that the MIP^® aerosol consists of a bimodal volume-weighted particle size distribution (PSD₃) with a median droplet diameter of x _50,3 = 25 µm. Calculations reveal that the droplet size for a homogenous intra-abdominal drug distribution during PIPAC therapy should be below 1.2 µm. We show that >97.5 vol% of the aerosolized liquid is delivered as droplets with ≥3 µm in diameter, which are primarily deposited on the surface beneath the MIP^® by gravitational settling and inertial impaction. These findings were confirmed by ex vivo gravimetric analyses, where more than 86.0 vol% of the aerosolized liquid was deposited within a circular area with a diameter of 15 cm.

CONCLUSIONS

The granulometric aerosol properties, as well as the aerodynamic conditions achieved by standard MIP^® operation, do not support the idea of widespread or homogenous drug distribution in the abdominal cavity.