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Simple Summary: Intraperitoneal (IP) administration of Paclitaxel (PTX) is a logical approach for treating peritoneal metastases (PMs), as it allows direct drug infiltration into PMs, providing prolonged exposure at high concentrations with minimal systemic side effects. However, the optimal timing for combining intravenous (IV) and IP administration remains uncertain. This study demonstrated that IP administration of PTX resulted in higher concentrations of PTX in peritoneal tumors, as well as increased levels of intravenously administered Carboplatin (CBDCA) when given four days after PTX administration. These findings suggest that IP PTX may enhance the efficacy of subsequent systemic chemotherapy. Therefore, staggered and repeated systemic chemotherapy following IP PTX appears to be a highly effective strategy for managing PMs. Despite advances in systemic chemotherapy, patients with gastric cancer (GC) and peritoneal metastases (PMs) continue to have poor prognoses. Intraperitoneal (IP) administration of Paclitaxel (PTX) combined with systemic chemotherapy shows promise in treating PMs from GC. However, methods of drug administration need to be optimized to maximize efficacy. In this study, we utilized a mouse model with PMs derived from a human GC cell line, administering PTX either IP or intravenously (IV), and Carboplatin (CBDCA) IV 0, 1, and 4 days after PTX administration. The PMs were resected 30 min later, and concentrations of PTX and CBDCA in resected tumors were measured using liquid chromatography–tandem mass spectrometry (LC-MS/MS). Results indicated that PTX concentrations were higher with IP administration than with IV administration, with significant differences observed on days 0 and 1. CBDCA concentrations 4 days post-IP PTX administration were higher than with simultaneous IV PTX administration. These findings suggest that IP PTX administration enhances CBDCA concentration in peritoneal tumors. Therefore, sequential IV administration of anti-cancer drugs appears more effective than simultaneous administration with IP PTX, a strategy that may improve prognoses for patients with PMs. [ABSTRACT FROM AUTHOR]

Simple Summary: Intraperitoneal (IP) chemotherapy is a treatment for cancers in the abdomen, delivering anti-cancer drugs directly into the peritoneal cavity. While this method has shown promising outcomes, limited drug penetration into tumors remains a challenge due to their unique pathophysiology. Our study aims to investigate drug delivery during IP chemotherapy using a mathematical model. We incorporated a real tumor image into our model to understand how tumor vessels and their distribution affect drug delivery. Our model allowed us to analyze the spatiotemporal distribution of drug concentration in the tumor. We also quantitatively evaluated treatment efficacy by examining drug availability in the tumor, drug penetration depth, and the fraction of killed cells during the treatment. Our findings revealed that each tumor's specific vascular network can impact drug delivery during IP chemotherapy. Our model provides valuable insights into the challenges of IP chemotherapy and holds promise for applications in personalized medicine. Intraperitoneal (IP) chemotherapy is a promising treatment approach for patients diagnosed with peritoneal carcinomatosis, allowing the direct delivery of therapeutic agents to the tumor site within the abdominal cavity. Nevertheless, limited drug penetration into the tumor remains a primary drawback of this method. The process of delivering drugs to the tumor entails numerous complications, primarily stemming from the specific pathophysiology of the tumor. Investigating drug delivery during IP chemotherapy and studying the parameters affecting it are challenging due to the limitations of experimental studies. In contrast, mathematical modeling, with its capabilities such as enabling single-parameter studies, and cost and time efficiency, emerges as a potent tool for this purpose. In this study, we developed a numerical model to investigate IP chemotherapy by incorporating an actual image of a tumor with heterogeneous vasculature. The tumor's geometry is reconstructed using image processing techniques. The model also incorporates drug binding and uptake by cancer cells. After 60 min of IP treatment with Doxorubicin, the area under the curve (AUC) of the average free drug concentration versus time curve, serving as an indicator of drug availability to the tumor, reached 295.18 mol·m−3·s−1. Additionally, the half-width parameter W1/2, which reflects drug penetration into the tumor, ranged from 0.11 to 0.14 mm. Furthermore, the treatment resulted in a fraction of killed cells reaching 20.4% by the end of the procedure. Analyzing the spatial distribution of interstitial fluid velocity, pressure, and drug concentration in the tumor revealed that the heterogeneous distribution of tumor vasculature influences the drug delivery process. Our findings underscore the significance of considering the specific vascular network of a tumor when modeling intraperitoneal chemotherapy. The proposed methodology holds promise for application in patient-specific studies. [ABSTRACT FROM AUTHOR]

Simple Summary: Cancer that spreads to the lining of the abdomen, the peritoneum, is currently treated with heated chemotherapy and surgery. However, the effects of the high temperature on the cancer cells and the immune cells are still unclear. In this review, we summarize the available data to show that high temperatures may have both positive and negative effects, and that further study is necessary to distinguish these effects. Hyperthermia combined with intraperitoneal (IP) drug delivery is increasingly used in the treatment of peritoneal metastases (PM). Hyperthermia enhances tumor perfusion and increases drug penetration after IP delivery. The peritoneum is increasingly recognized as an immune-privileged organ with its own distinct immune microenvironment. Here, we review the immune landscape of the healthy peritoneal cavity and immune contexture of peritoneal metastases. Next, we review the potential benefits and unwanted tumor-promoting effects of hyperthermia and the associated heat shock response on the tumor immune microenvironment. We highlight the potential modulating effect of hyperthermia on the biomechanical properties of tumor tissue and the consequences for immune cell infiltration. Data from translational and clinical studies are reviewed. We conclude that (mild) hyperthermia and HIPEC have the potential to enhance antitumor immunity, but detailed further studies are required to distinguish beneficial from tumor-promoting effects. [ABSTRACT FROM AUTHOR]

Simple Summary: Treatment with intraperitoneal hyperthermic chemotherapy (HIPEC) has been criticized in ovarian cancer due to the lack of prospective and randomized clinical trials demonstrating its efficacy in improving outcomes. However, the publication of the Dutch clinical trial five years ago has not changed the usual clinical practice within the Spanish peritoneal oncologic surgery group. In this paper we analyze and reflect on the future of this technique in patients with peritoneal dissemination of ovarian cancer. Ovarian cancer is the leading cause of death due to gynecological tumors in the female population. Despite optimal first-line treatment, including cytoreduction and platinum-based systemic chemotherapy, recurrences are frequent. The use of hyperthermic intraperitoneal chemotherapy (HIPEC) has been criticized, especially because of the lack of randomized controlled trials (RCTs) with convincing results to support the use of HIPEC in patients with ovarian cancer with peritoneal dissemination. In 2018, the clinical trial published by Van Driel et al. reported improved outcomes in favor of HIPEC treatment with cisplatin. In this study, we conducted a national survey within the Spanish group of peritoneal surgical oncology (Grupo Español de Cirugía Oncológica Peritoneal, GECOP) to explore the impact of the results of this RCT on clinical practice. A total of 33 groups completed the survey. Routine clinical practice was not changed in 28 of the 33 groups (85%) based on the results of the Van Driel trial. Despite the results of this RCT, most groups considered that more RCTs are needed and that, in the future, HIPEC may become the standard of care. In conclusion, the results from RCTs evaluating HIPEC treatment in patients with ovarian cancer has not been transferred to clinical practice. [ABSTRACT FROM AUTHOR]

Simple Summary: Peritoneal metastases have a poor prognosis, and one potential treatment option is cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC). The specific role of HIPEC is still poorly defined. In this cross-sectional study, we systematically analyzed all HIPEC trials registered on ClinicalTrials.gov to identify current research areas and to provide a perspective on expected outcomes. Only 11% (n = 26) of HIPEC trials registered on ClinicalTrials.gov (n = 234) have been published. The registered trials are very heterogeneous regarding methodological approaches and study designs. Currently, research is being conducted on 20 different drugs. The most studied cancers in HIPEC trials are peritoneal metastatic colorectal tumors, gastric cancer, and ovarian cancer. Introduction: Over the past two decades, cytoreductive surgery and HIPEC has improved outcomes for selected patients with peritoneal metastasis from various origins. This is a cross-sectional study with descriptive analyses of HIPEC trials registered on ClinicalTrials.gov. This study aimed to characterize clinical trials on HIPEC registered on ClinicalTrials.gov with the primary objective of identifying a trial focus and to examine whether trial results were published. Methods: The search included trials registered from 1 January 2001 to 14 March 2022. We examined the associations of exposure variables and other trial features with two primary outcomes: therapeutic focus and results reporting. Results: In total, 234 clinical trials were identified; 26 (11%) were already published, and 15 (6%) trials have reported their results but have not been published as full papers. Among ongoing nonpublished trials, 81 (39%) were randomized, 30 (14%) were blinded, n = 39 (20%) were later phase trials (i.e., phases 3 and 4), n = 152 (73%) were from a single institution, and 91 (44%) had parallel groups. Most of the trials were recruiting at the time of this analysis (75, 36%), and 39 (20%) were completed but had yet to publish results. In total, 68% of the trials focused on treatment strategies, and 53% investigated the oncological outcome. The most studied neoplasms for HIPEC trials were peritoneally metastasized colorectal cancer (32%), gastric cancer (29%), and ovarian cancer (26%). Twenty different drugs were analyzed in these clinical trials. Conclusions: Many study results are awaited from ongoing HIPEC trials. Most HIPEC trials focused on gastric, colorectal, or ovarian cancer. Many clinical trials were identified involving multiple entities and chemotherapeutic agents. [ABSTRACT FROM AUTHOR]

Simple Summary: Early diagnosis, evaluation, and appropriate treatment of peritoneal surface malignancies remains difficult. While computed tomography and magnetic resonance imaging are commonly used for these purposes, it remains unknown whether one is superior to the other. The aim of the current study was therefore to prospectively compare the two imaging modalities, using intra-operative evaluation as a reference standard. Our findings indicate that they are comparable in the detection and evaluation of peritoneal surface malignancies. Thus, either imaging modality may be appropriate, depending on clinical indications and resource management. It should however be noted that both modalities are likely to underestimate the true burden of disease, which may negatively impact treatment decisions. Background: The performance of MRI versus CT in the detection and evaluation of peritoneal surface malignancies (PSM) remains unclear in the current literature. Our study is the first prospective study in an Asian center comparing the two imaging modalities, validated against intra-operative findings. Methods: A total of 36 patients with PSM eligible for CRS-HIPEC underwent both MRI and CT scans up to 6 weeks before the operation. The scans were assessed for the presence and distribution of PSM and scored using the peritoneal cancer index (PCI), which were compared against PCI determined at surgery. Results: Both MRI and CT were 100% sensitive and specific in detecting the overall presence of PSM. Across all peritoneal regions, the sensitivity and specificity for PSM detection was 49.1% and 93.0% for MRI, compared to 47.8% and 95.1% for CT (p = 0.76). MRI was more sensitive than CT for small bowel disease, although the difference did not reach statistical significance. Comparing PCI on imaging with intra-operative PCI, the mean difference was found to be −3.4 ± 5.4 (p < 0.01) for MRI, and −3.9 ± 4.1 (p < 0.01) for CT. The correlation between imaging and intra-operative PCI was poor, with a concordance coefficient of 0.76 and 0.79 for MRI and CT, respectively. Within individual peritoneal regions, there was also poor agreement between imaging and intra-operative PCI for both modalities, other than in regions 1 and 3. Conclusion: MRI and CT are comparable in the detection and evaluation of PSM. While sensitive in the overall detection of PSM, they are likely to underestimate the true disease burden. [ABSTRACT FROM AUTHOR]

Simple Summary: The prognosis of gastric cancer (GC) patients with peritoneal carcinomatosis (PC) remains poor, in spite of the recent evolution of systemic chemotherapy for patients with GC. Nowadays, as intraperitoneal (IP) chemotherapy has been applied in the treatment for GC patients with PC, several promising data have been suggested. Inspired by the known characteristics of minimally invasive surgery (MIS), we have recently applied MIS concept in IP and systemic chemotherapy for GC patients with PC. We retrospectively compared the clinical outcomes between the patients underwent MIS conjoined IP plus systemic chemotherapy and patients underwent systemic chemotherapy only, to show the promising potential of the new treatment strategy combining MIS concept with IP plus systemic chemotherapy for GC patients with PC. Background: Peritoneal carcinomatosis (PC) is the most common form of metastasis in gastric cancer (GC) and is related with a poor prognosis. Several treatment modalities including systemic chemotherapy and intraperitoneal chemotherapy have been studied and adopted in treatment of GC patients with PC. Nevertheless, few studies have reported the comparison of the oncologic outcomes between minimally invasive surgery (MIS) with intraperitoneal (IP) chemotherapy and conventional chemotherapy for GC with PC. Methods: We retrospectively reviewed the clinical records of 74 patients who had been diagnosed as GC with PC via either intra-abdominal exploration or abdominopelvic computed tomography between January 2011 and April 2021. After performing propensity score-matching for this retrospective data, we compared the outcomes of 26 patients who underwent MIS followed by IP combined systemic chemotherapy (MIS-IP group) and 26 patients who underwent systemic chemotherapy only (SC-only group). Results: The 2-year progression free survival rate of the MIS-IP group was significantly higher than the SC-only groups (36.4% and 10.5%, respectively; p = 0.010). In multivariate analysis to detect relevant factors on PFS, IP chemotherapy (HR 0.213; p < 0.001), Eastern Cooperative Oncology Group performance status (HR 3.689; p = 0.002), and the amount of ascites (p = 0.011) were significant prognostic factors. Conclusions: This study demonstrated the therapeutic potential of MIS conjoined IP plus systemic chemotherapy for GC patients with PC. MIS conjoined by IP plus systemic chemotherapy can be adopted as a treatment option to reboot the role of IP chemotherapy in GC patients with PC. [ABSTRACT FROM AUTHOR]

Background: The development of chemoresistance to paclitaxel and carboplatin represents a major therapeutic challenge in ovarian cancer, a disease frequently characterized by malignant ascites and extrapelvic metastasis. Microtentacles (McTNs) are tubulin-based projections observed in detached breast cancer cells. In this study, we investigated whether ovarian cancers exhibit McTNs and characterized McTN biology., Methods: We used an established lipid-tethering mechanism to suspend and image individual cancer cells. We queried a panel of immortalized serous (OSC) and clear cell (OCCC) cell lines as well as freshly procured ascites and human ovarian surface epithelium (HOSE). We assessed by Western blot β-tubulin isotype, α-tubulin post-translational modifications and actin regulatory proteins in attached/detached states. We studied clustering in suspended conditions. Effects of treatment with microtubule depolymerizing and stabilizing drugs were described., Results: Among cell lines, up to 30% of cells expressed McTNs. Four McTN morphologies (absent, symmetric-short, symmetric-long, tufted) were observed in immortalized cultures as well as ascites. McTN number/length varied with histology according to metastatic potential. Most OCCC overexpressed class III ß-tubulin. OCCC/OSC cell lines exhibited a trend towards more microtubule-stabilizing post-translational modifications of α-tubulin relative to HOSE. Microtubule depolymerizing drugs decreased the number/length of McTNs, confirming that McTNs are composed of tubulin. Cells that failed to form McTNs demonstrated differential expression of α-tubulin- and actin-regulating proteins relative to cells that form McTNs. Cluster formation is more susceptible to microtubule targeting agents in cells that form McTNs, suggesting a role for McTNs in aggregation., Conclusions: McTNs likely participate in key aspects of ovarian cancer metastasis. McTNs represent a new therapeutic target for this disease that could refine therapies, including intraperitoneal drug delivery.

Gastric cancer carries a poor prognosis and is a leading cause of cancer-related mortality worldwide. Patients with gastric cancer who develop peritoneal metastases have an even more dismal prognosis, with median survival time measured in months. Since studies have demonstrated that systemic chemotherapy has poor penetration into the peritoneum, multimodal treatment with intraperitoneal chemotherapy has been proposed for the treatment of peritoneal metastases and has become the foundation for newer therapeutic techniques and clinical trials. These include heated intraperitoneal chemotherapy (HIPEC) with cytoreductive surgery (CRS), which involves the application of heated chemotherapy into the abdomen with or without tumor debulking surgery; normothermic intraperitoneal chemotherapy (NIPEC), in which non-heated chemotherapy can be delivered into the abdomen via a peritoneal port allowing for repeat dosing; and pressurized intraperitoneal aerosolized chemotherapy (PIPAC), a newer technique of pressurized and aerosolized chemotherapy delivered into the abdomen during laparoscopy. Early results with intraperitoneal chemotherapy have shown promise in increasing disease-free and overall survival in select patients. Additionally, there may be a palliative effect of these regional therapies. In this review, we explore and summarize these different intraperitoneal chemotherapy treatment regimens for gastric cancer with peritoneal metastases.

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. [ABSTRACT FROM AUTHOR]

The management of peritoneal metastases from gastric cancer origin has evolved considerably over the last three decades with the establishment of cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) as efficacious therapies in carefully selected patients. Other approaches such as the use of prophylactic/adjuvant HIPEC in patients who are considered high-risk and those with positive peritoneal cytology will benefit from additional data before being adopted into routine clinical practice. Lastly, there are new and emerging intraperitoneal chemotherapy techniques such as early post-operative intraperitoneal chemotherapy (EPIC) for residual microscopic disease, and pressurized intraperitoneal aerosolized chemotherapy (PIPAC) for patients with advanced unresectable peritoneal carcinomatosis, which are currently under evaluation in clinical trials. The following review outlines the natural history of gastric cancer, currently available neoadjuvant and adjuvant therapies for resectable disease, and existing evidence supporting various approaches to CRS and intraperitoneal chemotherapy. [ABSTRACT FROM AUTHOR]

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., Competing Interests: MAR is (co-)inventor of several patents on PIPAC and related procedures and receives royalties from these patents. The other authors declare no conflict of interest.