Peritoneal regression grading score (PRGS): first evidence for independent predictive and prognostic significance

PIPAC in patients with peritoneal metastases from gastrointestinal tract (PIPOX01): An open label, non-comparative phase 1/2 dose escalation and expansion trial

BACKGROUND

Despite modern systemic chemotherapy, survival remains poor for patients with advanced isolated peritoneal metastases from the gastrointestinal tract. We aimed to assess the safety and efficacy of pressurized intraperitoneal aerosol chemotherapy (PIPAC) with oxaliplatin.

PATIENTS AND METHODS

We conducted a phase 1/2, open label, non-comparative, dose escalation and expansion trial of PIPAC with oxaliplatin in patients with a peritoneal cancer index (PCI) of more than 5, 13 and 15 for respectively a gastric, small bowel and colorectal primary cancer, and who had received at least three months of systemic chemotherapy. PIPAC cycle lengths were 4-6 weeks with systemic chemotherapy allowed 15 days after each PIPAC. PCI and oxaliplatin tumor concentration were assessed every PIPAC cycle. The main endpoints were tolerability, tumor response, and survival.

RESULTS

Between 2017 and 2020, 34 patients were enrolled in three centers, in this phase 1/2 study, of whom 25 were evaluable at the recommended dose determined in the phase I trial (90 mg/m2 plus systemic 5-FU). Before inclusion, patients received a median of 2 [1-4] chemotherapy lines and had a median PCI of 22.5 [7-29]. At this dose, the safety profile showed acceptable tolerability. Eight patients (32 %) had grade 3/4 treatment-related adverse events. Minor (grade 1/2) adverse events were mainly abdominal pain (n = 19, 76 %) and nausea (n = 16, 64 %). Median PFS was 6.1 months and median OS was 13 months.

CONCLUSION

In patients with advanced and refractory peritoneal metastasis, PFS of 6.1 months is encouraging. A prospective randomized phase II study is required.

Pressurized Intraperitoneal Aerosol Chemotherapy (PIPAC) for Gastric Cancer Peritoneal Metastases: Results from the Lithuanian PIPAC Program

BACKGROUND

Peritoneal metastases (PM) of gastric cancer (GC) are considered a terminal condition, with reported median survival ranging from 2 to 9 months. Standard treatment typically involves systemic chemotherapy alone or combined with targeted therapy or immunotherapy, though efficacy is limited. Pressurized intraperitoneal aerosol chemotherapy (PIPAC) has emerged as a novel technique for treating GC PM, although it remains an experimental treatment under investigation. This study aimed to summarize the outcomes of GC PM treatment with PIPAC from the Lithuanian PIPAC program.

METHODS

All patients who underwent PIPAC for GC PM at Vilnius University Hospital Santaros Klinikos between 2015 and 2022 were included in this retrospective study. The safety of PIPAC was assessed by postoperative complications according to the Clavien-Dindo classification. Efficacy was evaluated based on the peritoneal carcinomatosis index (PCI), ascites dynamics throughout the treatment, and long-term outcomes.

RESULTS

In total, 32 patients underwent 71 PIPAC procedures. Intraoperative and postoperative morbidity related to PIPAC occurred after three (4.2%) procedures. Following PIPAC, there was a tendency towards a decrease in median PCI from 10 (Q1 3; Q3 13) to 7 (Q1 2; Q3 12), p = 0.75, and a decrease in median ascites volume from 1300 mL (Q1 500; Q3 3600) at the first PIPAC to 700 mL (Q1 250; Q3 4750) at the last PIPAC, p = 0.56; however, these differences were not statistically significant. The median overall survival after PM diagnosis was 12.5 months (95% CI 10-17), and the median survival after the first PIPAC procedure was 5 months (95% CI 4-10).

CONCLUSIONS

PIPAC is a safe and feasible treatment option for GC PM; however, well-designed prospective studies are needed to fully assess its efficacy.

Outcome of patients with peritoneal metastasis from ovarian cancer treated with Pressurized IntraPeritoneal Aerosol Chemotherapy (PIPAC)

Objectives

There are few data on Pressurized IntraPeritoneal Aerosol Chemotherapy with cisplatin and doxorubicin (PIPAC C/D) in women with primary unresectable or recurrent platinum-resistant peritoneal metastasis (PM) from ovarian cancer (OC). We evaluated survival, histological and cytological response, Quality of Life (QoL) and toxicity after PIPAC C/D in these patients.

Methods

Retrospective analysis of patients from the prospective PIPAC-OPC1 and -OPC2 studies. The histological response was evaluated by the Peritoneal Regression Grading Score (PRGS). QoL questionnaires were collected at baseline and after third PIPAC or 60 days. Adverse events were collected until 30 days after the last PIPAC. Demographic and survival data were analysed based on intention to treat. Response, QoL and toxicity were analysed per protocol (≥1 PIPAC).

Results

Twenty-nine patients were included. Five patients (17 %) were non-accessible at PIPAC 1. One patient was excluded due to liver metastases at PIPAC 1. Thus, 23 patients had 76 PIPACs (median 2, range 1-12). Median overall survival was 8.2 months (95 % CI 4.4-10.3) from PIPAC 1. Biopsy data were available for 22 patients, and seven (32 %) patients had a major/complete histological response (PRGS≤2) at PIPAC 3. No cytological conversions were registered. Symptoms and function scores worsened, while emotional scores improved. Three patients had severe adverse reactions (two ileus, one pulmonary embolism); no life-threatening reactions or treatment-related mortality was observed.

Conclusions

PIPAC C/D was feasible and induced histological regression in a substantial proportion of patients with platinum-resistant PM from OC. Larger studies are needed to evaluate impact on survival.

RNA expression profiling of peritoneal metastasis from pancreatic cancer treated with Pressurized Intraperitoneal Aerosol Chemotherapy (PIPAC)

Objectives

Pressurized Intraperitoneal Aerosol Chemotherapy (PIPAC) is an experimental treatment option in peritoneal metastasis from pancreatic cancer (PM-PC). Aims were to examine mRNA profile of fibrosis due to response after systemic chemotherapy and PIPAC (Regression) compared to treatment-naïve PM-PC and chronic cholecystitis-related peritoneal fibrosis (Controls).

Methods

Peritoneal biopsies (PBs) from PM-PC patients who had undergone systemic chemotherapy and PIPAC were evaluated with Peritoneal Regression Grading Score (PRGS). We extracted RNA from PBs with Regression (PRGS 1, n=11), treatment-naïve PM-PC (n=10), and Controls (n=10). Profiling of 800 mRNAs was performed (NanoString nCounter, PanCancer Immuno-Oncology 360 (IO-360) and 30 additional stroma-related mRNAs).

Results

Regression vs. PM-PC identified six up-regulated and 197 down-regulated mRNAs (FDR≤0.05), linked to TNF-α signaling via NF-kB, G2M checkpoint, epithelial-mesenchymal transition, estrogen response, and coagulation. Regression vs. Controls identified 43 significantly up-regulated mRNAs, linked to interferon-α response, and down-regulation of 99 mRNAs, linked to TNF-α signaling via NF-kB, inflammatory response, epithelial-mesenchymal transition, KRAS signaling, and hypoxia (FDR≤0.05).

Conclusions

In regressive fibrosis of PM-PC after systemic chemotherapy and PIPAC (Regression), downregulation of mRNAs related to key tumor biological pathways was identified. Regression also showed transcriptional differences from unspecific, benign fibrosis (Controls). Future studies should explore whether mRNA profiling of PBs with PM from PC or other primaries holds prognostic or predictive value.

What is long-term survival in patients with peritoneal metastasis from gastric, pancreatic, or colorectal cancer? A study of patients treated with systemic chemotherapy and pressurized intraperitoneal aerosol chemotherapy (PIPAC)

Objectives

A definition of long-term survival (LTS) in patients with peritoneal metastasis (PM) from gastric cancer (GC), pancreatic cancer (PC) or colorectal cancer (CRC) treated with systemic chemotherapy and pressurized intraperitoneal aerosol chemotherapy (PIPAC) is lacking. We aimed to define LTS and investigate characteristics and treatment response in patients who reached LTS in data from two prospective trials.

Methods

Retrospective study of patients with GC-, PC-, or CRC-PM from the prospective PIPAC-OPC1 and PIPAC-OPC2 studies. The definition of LTS was based on published systematic reviews and randomized controlled trials. LTS was defined at the time point where 25 % of the patients were alive in these studies. Histology based response was evaluated by the mean Peritoneal Regression Grading Score (PRGS) using biopsies obtained prior to PIPAC 3, and defined by a mean PRGS of ≤2.0 or a decrease of mean PRGS of ≥1, compared to baseline.

Results

LTS was defined at 21 (GC), 15 (PC), and 24 (CRC) months. Fifty-one (47.2 %) patients (nine GC, 17 PC, 25 CRC) reached LTS calculated from the date of PM diagnosis. All but one received palliative chemotherapy before PIPAC, and 37 % received bidirectional treatment. More than 90 % of the LTS patients had response according to PRGS. The mOS from PIPAC 1 was 23.3, 12.4, and 28.5 months for GC, PC, and CRC LTS patients.

Conclusions

Patients with PM from GC, PC, and CRC treated with systemic chemotherapy and PIPAC can reach LTS and most show histological response. Causality must be further investigated.

The Role of Additional Staining in the Assessment of the Peritoneal Regression Grading Score (PRGS) in Peritoneal Metastasis of Gastric Origin

INTRODUCTION

The Peritoneal Regression Grading Score (PRGS) is a 4-tied histologic regression grading score for determining the response of peritoneal metastasis to chemotherapy. Peritoneal biopsies in every abdominal quadrant are recommended. A positive therapy response is defined as a decreasing or stable mean PRGS between 2 therapy cycles. The added value of periodic acid satin (PAS) and Ber-EP4 staining over HE staining for diagnosing PRGS1 (the absence of vital tumor cells) is unclear.

MATERIALS AND METHODS

A total of 339 biopsies obtained during 76 laparoscopies in 33 patients with peritoneal metastasis of gastric cancer were analyzed. Biopsies classified as PRGS 1 (no residual tumor, n=95) or indefinite (n=50) were stained with PAS, and remaining indefinite or PRGS1 cases additionally stained with BerEP4.

RESULTS

After PAS-staining tumor cells were detected in 28 out of 145 biopsies (19%), the remaining 117 biopsies were immunostained with Ber-EP4. Tumor cells were detected in 22 biopsies (19%). In total, additional staining allowed the detection of residual tumor cells in 50 out of 339 biopsies (15%) and changed the therapy response assessment in 7 out of 33 (21%) patients.

CONCLUSIONS

In summary, 25% (24 out of 95) of initially tumor-free samples (PRGS1) showed residual tumor cells after additional staining with PAS and/or BerEp4. Immunohistochemistry provided important additional information (the presence of tumor cells) in 22 of all 339 biopsies (11.2%). Further staining reduced the instances of unclear diagnosis from 50 to 0 and changed the therapy response assessment in 7 out of 33 patients (21%). We recommend additional staining in PRGS1 or unclear cases.