P50. Pressurized Intraperitoneal Aerosolized Chemotherapy: A Pilot Study to Evaluate Patients with Peritoneal Carcinomatosis from Gastrointestinal Malignancies

Introduction

Pressurized Intraperitoneal Aerosol Chemotherapy (PIPAC) represents an innovative therapeutic option for patients with gastrointestinal (GI) malignancies presenting with isolated peritoneal metastasis who are not candidates for cytoreductive surgery (CRS) with or without heated intraperitoneal chemotherapy (HIPEC). This study evaluates the implementation of a PIPAC program at a tertiary center specializing in peritoneal surface malignancies.

Methods

A registry study was designed to enroll patients diagnosed with GI cancers metastatic to the peritoneum only. Eligible participants had previously received a minimum of two lines of systemic therapy and were determined by the surgical team to be unsuitable for CRS-HIPEC at enrollment. The protocol involved administration of three cycles of PIPAC (utilizing oxaliplatin or cisplatin/doxorubicin), followed by standard of care systemic chemotherapy. Cross-sectional imaging was obtained after each cycle to assess disease response or progression. Quality of life (QOL) measures were collected before and after each PIPAC cycle. Assessment of treatment efficacy encompassed safety, pathological response, QOL, and clinical outcomes.

Results

Nine patients have been enrolled thus far: 6 with appendiceal, 1 with colon, and 2 with gastric adenocarcinomas. Among these, 2 were goblet cell carcinoma and 3 had signet ring features. Six patients had undergone prior surgical resection for cancer. Of the cohort, 5 have completed all prescribed PIPAC cycles, 2 remain on active treatment, and 2 were discontinued due to disease progression. No Clavien-Dindo grade 3+ complications were observed. All patients were discharged after overnight hospital stay. Median baseline peritoneal cancer index (PCI) was 20. Among those who completed the protocol, PCI score decreased by a median of 5 points. Peritoneal Regression Grading Score (PRGS) improved significantly in 86%, with many exhibiting major pathologic response with fibrosis (Figure). Notably, two patients became eligible for CRS ± HIPEC following 3 PIPAC treatments. Survey data indicated stable symptoms and QOL across treatment cycles, with no decline noted.

Conclusions

PIPAC appears to be a safe and well-tolerated therapy for patients with GI malignancies and peritoneal metastases who are not eligible for CRS. Evidence suggests potential for pathologic response, enabling some patients to become candidates for subsequent CRS-HIPEC. Additional studies are warranted to clarify the impact of PIPAC on clinical outcomes and survival.