A Comparison of Intravenous plus Intraperitoneal Chemotherapy with Intravenous Chemotherapy Alone for the Treatment of Gastric Cancer: A Meta-Analysis

Optimizing Timing of Intraperitoneal Chemotherapy to Enhance Intravenous Carboplatin Concentration

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.

Regional Therapy Approaches for Gastric Cancer with Limited Peritoneal Disease

PURPOSE

Despite advances in systemic therapy, outcomes of patients with gastric cancer (GC) peritoneal carcinomatosis (PC) remain poor, in part because of poor penetrance of systemic therapy into peritoneal metastasis due to the plasma-peritoneal barrier and anarchic intra-tumoral circulation. Hence, regional treatment approach with administration of chemotherapy directly into the peritoneal cavity (intraperitoneal, IP) under various conditions, combined with or without cytoreductive surgery (CRS) has remained an area of significant research interest. The purpose of this review is to provide high-level evidence for regional treatment approaches in the management of GCPC with limited peritoneal disease.

METHODS

A review of the current literature and ongoing clinical trials for regional IP therapies for GCPC was performed. Studies included in this review comprise of phase III randomized controlled trials, non-randomized phase II studies, high-impact retrospective studies, and active ongoing clinical trials for each available IP modality.

RESULTS

The three common IP approaches are heated intraperitoneal chemotherapy (HIPEC), normothermic intraperitoneal chemotherapy (NIPEC) and more recently introduced, pressurized intraperitoneal aerosolized chemotherapy (PIPAC). These IP approaches have been combined with systemic therapy and/or CRS with varying degrees of promising results, demonstrating evidence of improvements in survival rates and peritoneal disease control. Patient selection, optimization of systemic therapy, and completeness of cytoreduction have emerged as major factors influencing the design of contemporary and ongoing trials.

CONCLUSION

IP chemotherapy has a clear role in the management of patients with GCPC, and when combined with CRS in appropriately selected patients has the potential to significantly improve survival. Ongoing and upcoming IP therapy clinical trials hold great promise to shape the treatment paradigm for GCPC.

Phase II clinical trial of sequential treatment with systemic chemotherapy and intraperitoneal paclitaxel for gastric and gastroesophageal junction peritoneal carcinomatosis - STOPGAP trial

BACKGROUND

Studies from Asia indicate that normothermic intraperitoneal chemotherapy (NIPEC) may confer survival benefit in patients with gastric peritoneal carcinomatosis (PC). However, data regarding this approach is lacking in western population. The current STOPGAP trial is intended to assess 1-year progression-free survival benefit of sequential systemic chemotherapy and paclitaxel NIPEC in patients with gastric/ gastroesophageal junction (GEJ) adenocarcinoma PC.

METHODS

This is a prospective, single center, single arm, phase II investigator-initiated clinical trial. Patients with histologically proven gastric/GEJ (Siewert 3) adenocarcinoma with positive peritoneal cytology or PC will be eligible to participate after three months of standard of care systemic chemotherapy and with no evidence of visceral metastasis on restaging scans. The primary treatment is iterative paclitaxel NIPEC with systemic paclitaxel and 5-fluorouracil, which will be administered on days1 and 8 and repeated every three weeks for 4 cycles. Patients will undergo diagnostic laparoscopy both before and after NIPEC to assess peritoneal cancer index (PCI). Patients with PCI less than or equal to 10 in whom complete cytoreduction (CRS) is feasible may opt to undergo CRS with heated intraperitoneal chemotherapy (HIPEC). The primary endpoint is 1-year progression free survival and secondary endpoints are overall survival and patient reported quality of life outcomes measured by EuroQol- 5 dimensions-5 level (EuroQol-5D-5L) questionnaire.

DISCUSSION

If the sequential approach of systemic chemotherapy followed by paclitaxel NIPEC proves beneficial, then this approach could be used in larger, muti-institutional randomized clinical trial of gastric PC.

TRIAL REGISTRATION

The trial was registered on 21/02/2021, under clinical trials.gov; Identifier: NCT04762953.

Efficacy and Safety of Conversion Therapy by Intraperitoneal and Intravenous Paclitaxel Plus Oral S-1 in Gastric Cancer Patients With Peritoneal Metastasis: A Prospective Phase II Study

Background

Neoadjuvant intraperitoneal and systemic chemotherapy (NIPS) has shown promising results in gastric cancer (GC) with peritoneal metastasis. However, clinical practice experience of NIPS is still lacking in China. In this study, we investigate the efficacy and safety of NIPS in Chinese patients.

Methods

Eligible patients received NIPS every 3 weeks. Gastrectomy was performed for patients who met the criteria of conversion surgery. The primary end point was 1-year overall survival (OS) rate. Secondary end points were the response rate, toxic effects, conversion surgery outcomes and median survival time (MST).

Results

Sixty-seven patients were enrolled. The primary endpoint was achieved with 1-year OS rate reached 67.2% (95% CI, 56.8%-79.4%). Conversion surgery was performed in 42 patients (62.9%), and R0 resection was achieved in 23 patients (54.8%) with the MST of 31.3 months (95% CI, 24.3-38.3). And the MST was 19.3 months (95% CI, 16.4-22.2) for all patients. Toxicity and surgical complications were well-tolerated. Moreover, sex, R0 resection, pathological nodal stage and tumor regression grade (TRG) were independent prognostic factors for patients who underwent conversion surgery.

Conclusion

The NIPS is effective and safe in treating GC patients with peritoneal metastasis. Male patients, patients who underwent R0 resection, patients with ypN0-1 or TRG 1 after conversion surgery are more likely to benefit from the NIPS.

Clinical Trial Registration

http://www.chictr.org.cn/, identifier https://clinicaltrials.gov/ (<ChiCTR2200056029>).

Can We Reboot the Role of Intraperitoneal Chemotherapy in the Treatment for Gastric Cancer with Peritoneal Carcinomatosis?: A Retrospective Cohort Study Regarding Minimally Invasive Surgery Conjoined with Intraperitoneal plus Systemic Chemotherapy

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.

Hyperthermic Intraperitoneal Chemotherapy plus Intravenous Chemotherapy of Paclitaxel with or without Sintilimab in Gastric Cancer: A Comparative Study

Objective

To compare the clinical efficacy of hyperthermic intraperitoneal chemotherapy (HIPEC) plus intravenous chemotherapy of paclitaxel with or without sintilimab in peritoneal metastasis of gastric cancer.

Methods

A total of 120 patients assessed for eligibility with peritoneal metastasis of gastric cancer treated in the oncology department of our hospital from January 2019 to June 2020 were recruited. They were concurrently randomly assigned in a 1 : 1 ratio to receive HIPEC plus sintilimab-paclitaxel intravenous chemotherapy (study group) or plus paclitaxel intravenous chemotherapy only (control group).

Results

The objective remission rate (ORR) of ascites in the study group was significantly higher than that in the control group. Subgroup analysis showed that an age ≤60 years or well-differentiated tumors were associated with better objective remission. After treatment, significantly higher Karnofsky Performance Status (KPS) scores were observed in the study group versus those of the control group. Adverse events reported were comparable between groups. The study group obtained longer 12-month progression-free survival (PFS) and overall survival (OS) than those of the control group.

Conclusion

On top of HIPEC, intravenous chemotherapy with sintilimab and paclitaxel constitute an effective alternative for patients with peritoneal metastasis of gastric cancer to enhance ascites remission, ameliorate the quality of life, and prolong survival, versus with paclitaxel alone.

Bioengineering of virus-like particles as dynamic nanocarriers for in vivo delivery and targeting to solid tumours

Virus-like particles (VLPs) are known as self-assembled, non-replicative and non-infectious protein particles, which imitate the formation and structure of original wild type viruses, however, lack the viral genome and/or their fragments. The capacity of VLPs to encompass small molecules like nucleic acids and others has made them as novel vessels of nanocarriers for drug delivery applications. In addition, VLPs surface have the capacity to achieve variation of the surface display via several modification strategies including genetic modification, chemical modification, and non-covalent modification. Among the VLPs nanocarriers, Hepatitis B virus core (HBc) particles have been the most encouraging candidate. HBc particles are hollow nanoparticles in the range of 30-34 nm in diameter and 7 nm thick envelopes, consisting of 180 or 240 copies of identical polypeptide monomer. They also employ a distinctive position among the VLPs carriers due to the high-level synthesis, which serves as a strong protective capsid shell and efficient self-assembly properties. This review highlights on the bioengineering of HBc particles as dynamic nanocarriers for in vivo delivery and specific targeting to solid tumours.

Prognostic value of CEA/CA72-4 immunohistochemistry in combination with cytology for detecting tumor cells in peritoneal lavage in gastric cancer

Aim: To study the value and efficiency of CEA/CA72-4 immunohistochemistry in detecting free tumor cells from peritoneal lavage, in order to provide reliable lab information for subsequent intraperitoneal chemotherapy. Methods: A total of 112 progressive gastric cancer patients were enrolled from Oct. 2016 to Oct 2017, who were pathologically diagnosed as gastric cancer after surgery. Peritoneal lavage was respectively collected during operation. Cytology and CEA/CA72-4 immunohistochemistry of peritoneal lavage samples was performed. Overall survival and recurrence free survival was analyzed. Results: Cytology showed 16 positive cases (14.29%), CEA immunohistochemistry showed 29 positive cases (25.89%), CA72-4 immunohistochemistry showed 33 positive cases (29.46%). McNemar's test showed significant difference in positivity between cytology (CY+) and CEA/CA72-4 immunohistochemistry (IHC+). Kappa test showed consistency between immunohistochemistry of CEA and CA72-4 with cytology. Patients with CY+/IHC+ had the poorest overall survival (OS) as well as recurrence free survival (RFS), followed by those with CY+ or IHC+, while those with CY-/IHC- had higher OS and RFS. The differences of OS and RFS in IHC+ group were worse than that in IHC- group. Kaplan-Meier analysis showed that positive CEA/CA72-4 IHC revealed poorer prognosis than the negative cases. Conclusions: Due to the limitation of cytology, combination of cytology and immunohistochemistry appears to be more efficient for predicting prognosis of progressive gastric cancer.

The levels of SYT13 and CEA mRNAs in peritoneal lavages predict the peritoneal recurrence of gastric cancer

BACKGROUND

Although peritoneal lavage cytology often serves as a sensitive method to detect free cancer cells in the abdominal cavity, some patients experience peritoneal recurrence despite negative cytology. The aim of this study was to evaluate mRNAs in peritoneal lavage fluid as potential markers for predicting the peritoneal recurrence of gastric cancer (GC).

METHODS

Peritoneal lavage fluid samples were obtained during surgery conducted on 187 patients with GC and from 30 patients with non-malignant disease (controls). The mRNA levels of nine candidate markers were quantified, and analysis of a receiver-operating characteristic curve compared their accuracies. The cutoff was defined as the highest value of the controls.

RESULTS

Synaptotagmin XIII (SYT13) and carcinoembryonic antigen (CEA) mRNA levels were analyzed further. SYT13 levels were significantly associated with shorter peritoneal recurrence-free survival (PRFS) and overall survival. Among patients with negative peritoneal lavage cytology, those positive for either SYT13 or CEA mRNA experienced significantly shorter peritoneal recurrence-free survival compared with those with negative fluid (hazards ratio [HR] 4.21, P = 0.0114; HR 3.53; P = 0.0426, respectively). Univariate analysis revealed that SYT13 and CEA mRNA levels were significant predictors of peritoneal recurrence. Positive levels of both SYT13 and CEA mRNA demonstrated the highest HR for peritoneal recurrence (HR 12.27, P = 0.0064). Multivariable analysis revealed that SYT13 positivity was a significant independent prognostic factor (HR 3.69; 95% confidence interval, 1.18-12.74; P = 0.0246).

CONCLUSIONS

Combined measurement of SYT13 and CEA mRNA levels in peritoneal lavage fluid could serve as a promising approach to predict peritoneal recurrence of GC.

Pressurized intraperitoneal aerosol chemotherapy and its effect on gastric-cancer-derived peritoneal metastases: an overview

This manuscript aspires to portray a review of the current literature focusing on manifest peritoneal metastasis (PM) derived from gastric cancer and its treatment options. Despite the development of chemotherapy and multimodal treatment options during the last decades, mortality remains high worldwide. After refreshing important epidemiological considerations, the molecular mechanisms currently accepted through which PM occurs are revised. Palliative chemotherapy is the only recommended treatment option for patients with PM of gastric cancer according to the National Comprehensive Cancer Network guidelines, although cytoreductive surgery in combination with hyperthermic intraperitoneal chemotherapy demonstrated promising results in selected patients with regional PM and localized intraabdominal tumor spread. A novel treatment named pressurized intraperitoneal aerosol chemotherapy may have a promising future in improving overall survival with an acceptable postoperative complication rate and stabilizing quality of life during treatment. Additionally, the procedure has been proved to be safe for the patient and medical personnel and a feasible, repeatable method to deter metastatic proliferation. This overview comprehensively addresses this novel and promising treatment in the context of a scientifically and clinically challenging disease.

In Vivo and Cellular Trafficking of Acetalated Dextran Microparticles for Delivery of a Host-Directed Therapy for Salmonella enterica Serovar Typhi Infection

Previously we have encapsulated host-directed therapy AR-12 into acetalated dextran (Ace-DEX) microparticles (MPs) to mitigate drug toxicity and passively target phagocytic host cells. Herein, we have improved upon our initial emulsion-based formulation of Ace-DEX MPs encapsulating AR-12 (AR-12/MPs) by improving the drug encapsulation efficiency, evaluating sterilization processes for manufacturing, and understanding cellular and in vivo trafficking of the MPs. By using an alternative solvent system, ethyl acetate, we report an increased encapsulation efficiency of AR-12 while maintaining the pH-responsive degradation kinetics of Ace-DEX MPs. To better manufacture this novel antimicrobial formulation, we sterilized AR-12/MPs by gamma irradiation or ethylene oxide and evaluated their efficacy against intracellular Salmonella enterica serovar Typhi. Sterilized AR-12/MPs resulted in a significant reduction in intracellular bacterial burden compared to Blank/MPs. We also characterized intracellular trafficking of Ace-DEX MPs encapsulating fluorophores, which demonstrated internalization of MPs in endo/lysosomal compartments and time and degradation-rate dependent lysosomal escape into cytosolic compartments. Additionally, in vivo toxicity was mitigated following encapsulation of AR-12, where the maximum tolerated dose of AR-12 was increased compared to soluble treatment via intranasal, intravenous, and intraperitoneal administration routes. Following in vivo trafficking of Ace-DEX MPs via the same routes, intranasal administration demonstrated the highest accumulation in the lungs, liver, and kidneys, which persisted out to 240 h. Overall, we have advanced the formulation of this host-directed therapy and broadened the understanding of Ace-DEX MP delivery.

Phase III Trial Comparing Intraperitoneal and Intravenous Paclitaxel Plus S-1 Versus Cisplatin Plus S-1 in Patients With Gastric Cancer With Peritoneal Metastasis: PHOENIX-GC Trial

Purpose Intraperitoneal paclitaxel plus systemic chemotherapy demonstrated promising clinical effects in patients with gastric cancer with peritoneal metastasis. We aimed to verify its superiority over standard systemic chemotherapy in overall survival. Patients and Methods This randomized phase III trial enrolled patients with gastric cancer with peritoneal metastasis who had received no or short-term (< 2 months) chemotherapy. Patients were randomly assigned at a two-to-one ratio to receive intraperitoneal and intravenous paclitaxel plus S-1 (IP; intraperitoneal paclitaxel 20 mg/m² and intravenous paclitaxel 50 mg/m² on days 1 and 8 plus S-1 80 mg/m² per day on days 1 to 14 for a 3-week cycle) or S-1 plus cisplatin (SP; S-1 80 mg/m² per day on days 1 to 21 plus cisplatin 60 mg/m² on day 8 for a 5-week cycle), stratified by center, previous chemotherapy, and extent of peritoneal metastasis. The primary end point was overall survival. Secondary end points were response rate, 3-year overall survival rate, and safety. Results We enrolled 183 patients and performed efficacy analyses in 164 eligible patients. Baseline characteristics were balanced between the arms, except that patients in the IP arm had significantly more ascites. The median survival times for the IP and SP arms were 17.7 and 15.2 months, respectively (hazard ratio, 0.72; 95% CI, 0.49 to 1.04; stratified log-rank P = .080). In the sensitivity analysis adjusted for baseline ascites, the hazard ratio was 0.59 (95% CI, 0.39 to 0.87; P = .008). The 3-year overall survival rate was 21.9% (95% CI, 14.9% to 29.9%) in the IP arm and 6.0% (95% CI, 1.6% to 14.9%) in the SP arm. Both regimens were well tolerated. Conclusion This trial failed to show statistical superiority of intraperitoneal paclitaxel plus systemic chemotherapy. However, the exploratory analyses suggested possible clinical benefits of intraperitoneal paclitaxel for gastric cancer.

An abscopal effect in a case of concomitant treatment of locally and peritoneally recurrent gastric cancer using adoptive T-cell immunotherapy and radiotherapy

The mechanism of abscopal effect is becoming clear by the progress of cancer immunology. A 54‐year‐old male with recurrent gastric cancer presented an abscopal effect after radiotherapy with concurrent adoptive T‐cell immunotherapy (immunoradiotherapy). Immunoradiotherapy has potential to induce abscopal effect by strengthening systemic antitumor immunity even in recurrent cancer.

Engineering hepatitis B virus core particles for targeting HER2 receptors in vitro and in vivo

Hepatitis B Virus core (HBc) particles have been studied for their potential as drug delivery vehicles for cancer therapy. HBc particles are hollow nano-particles of 30–34 nm diameter and 7 nm thick envelopes, consisting of 180–240 units of 21 kDa core monomers. They have the capacity to assemble/dis-assemble in a controlled manner allowing encapsulation of various drugs and other biomolecules. Moreover, other functional motifs, i.e. receptors, receptor binding sequences, peptides and proteins can be expressed. This study focuses on the development of genetically modified HBc particles to specifically recognise and target human epidermal growth factor receptor-2 (HER2)-expressing cancer cells, in vitro and in vivo, for future cancer therapy. The non-specific binding capacity of wild type HBc particles was reduced by genetic deletion of the sequence encoding arginine-rich domains. A specific HER2-targeting was achieved by expressing the Z_HER2 affibodies on the HBc particles surface. In vitro studies showed specific uptake of Z_HER2-ΔHBc particles in HER2 expressing cancer cells. In vivo studies confirmed positive uptake of Z_HER2-ΔHBc particles in HER2-expressing tumours, compared to non-targeted ΔHBc particles in intraperitoneal tumour-bearing mice models. The present results highlight the potential of these nanocarriers in targeting HER2-positive metastatic abdominal cancer following intra-peritoneal administration.

iRGD peptide conjugation potentiates intraperitoneal tumor delivery of paclitaxel with polymersomes

Polymersomes are versatile nanoscale vesicles that can be used for cytoplasmic delivery of payloads. Recently, we demonstrated that pH-sensitive polymersomes exhibit an intrinsic selectivity towards intraperitoneal tumor lesions. A tumor homing peptide, iRGD, harbors a cryptic C-end Rule (CendR) motif that is responsible for neuropilin-1 (NRP-1) binding and for triggering extravasation and tumor penetration of the peptide. iRGD functionalization increases tumor selectivity and therapeutic efficacy of systemic drug-loaded nanoparticles in many tumor models. Here we studied whether intraperitoneally administered paclitaxel-loaded iRGD-polymersomes show improved efficacy in the treatment of peritoneal carcinomatosis. First, we demonstrated that the pH-sensitive polymersomes functionalized with RPARPAR (a prototypic CendR peptide) or iRGD internalize in the cells that express NRP-1, and that internalized polymersomes release their cargo inside the cytosol. CendR-targeted polymersomes loaded with paclitaxel were more cytotoxic on NRP-1-positive cells than on NRP-1-negative cells. In mice bearing peritoneal tumors of gastric (MKN-45P) or colon (CT26) origin, intraperitoneally administered RPARPAR and iRGD-polymersomes showed higher tumor-selective accumulation and penetration than untargeted polymersomes. Finally, iRGD-polymersomes loaded with paclitaxel showed improved efficacy in peritoneal tumor growth inhibition and in suppression of local dissemination compared to the pristine paclitaxel-polymersomes or Abraxane. Our study demonstrates that iRGD-functionalization improves efficacy of paclitaxel-polymersomes for intraperitoneal treatment of peritoneal carcinomatosis.

Prognostic value of serum tumor abnormal protein in gastric cancer patients

Aberrant glycosylation of protein occurs in nearly all types of cancers and has been confirmed to be associated with tumor progression, metastasis and the survival rate of patients. The present study aimed to explore the prognostic value of tumor abnormal protein (TAP) in gastric cancer patients. TAP was detected in the blood of 42 gastric cancer patients and 56 healthy volunteers by using the TAP testing kit. Univariate and multivariate Cox regression analysis were performed to evaluate the prognostic value of TAP. In total, 64.3% of gastric cancer patients were positive for TAP, and TAP was significantly correlated with poor prognosis [progression-free survival (PFS), 4.2 vs. 12.6 months; P=0.043]. TAP [hazard ratio (HR), 64.487; P<0.01), differentiation (HR, 17.279; P<0.01) and TNM stage (HR, 45.480; P<0.01) were found to be independent predictive factors for PFS. Furthermore, Kaplan-Meier curves indicated that TAP is associated with a reduced PFS in gastric cancer patients. The results of the present study therefore indicated that the TAP test has significant prognostic value for gastric cancer patients.

Paclitaxel-Loaded Polymersomes for Enhanced Intraperitoneal Chemotherapy

Peritoneal carcinomatosis is present in more than 60% of gastric cancer, 40% of ovarian cancer, and 35% of colon cancer patients. It is the second most common cause of cancer-related mortality, with a median survival of 1 to 3 months. Cytoreductive surgery combined with intraperitoneal chemotherapy is the current clinical treatment, but achieving curative drug accumulation and penetration in peritoneal carcinomatosis lesions remains an unresolved challenge. Here, we used flexible and pH-sensitive polymersomes for payload delivery to peritoneal gastric (MKN-45P) and colon (CT26) carcinoma in mice. Polymersomes were loaded with paclitaxel and in vitro drug release was studied as a function of pH and time. Paclitaxel-loaded polymersomes remained stable in aqueous solution at neutral pH for up to 4 months. In cell viability assay on cultured cancer cell lines (MKN-45P, SKOV3, CT26), paclitaxel-loaded polymersomes were more toxic than free drug or albumin-bound paclitaxel (Abraxane). Intraperitoneally administered fluorescent polymersomes accumulated in malignant lesions, and immunofluorescence revealed an intense signal inside tumors with no detectable signal in control organs. A dual targeting of tumors was observed: direct (circulation-independent) penetration, and systemic, blood vessel-associated accumulation. Finally, we evaluated preclinical antitumor efficacy of paclitaxel-polymersomes in the treatment of MKN-45P disseminated gastric carcinoma using a total dose of 7 mg/kg. Experimental therapy with paclitaxel-polymersomes improved the therapeutic index of drug over free paclitaxel and Abraxane, as evaluated by intraperitoneal tumor burden and number of metastatic nodules. Our findings underline the potential utility of the polymersome platform for delivery of drugs and imaging agents to peritoneal carcinomatosis lesions. Mol Cancer Ther; 15(4); 670-9. ©2016 AACR.