Outcomes of phosphorus-32 microparticle intratumoral implantation added to chemotherapy in patients with metastatic pancreatic adenocarcinoma

Background and Aims

Metastatic pancreatic ductal adenocarcinoma (mPDAC) has a 5-year survival rate of 3%. In nonmetastatic, locally advanced pancreatic cancer, the addition to chemotherapy of EUS-guided intratumoral phosphorus-32 (³²P) microparticle implantation has achieved good local disease control. The aim of this study was to report the clinical outcomes of this treatment in patients with mPDAC.

Methods

Patients with mPDAC treated with chemotherapy and intratumoral ³²P-microparticles from 5 centers in Australia and the United Kingdom were analyzed retrospectively.

Results

Fourteen patients were treated (7 female subjects; median age, 64.5 years; Eastern Cooperative Oncology Group performance status scores 0/1/2, 21.4%/57.1%/21.4%). The median baseline primary tumor longest diameter was 40.5 mm. Patients had a median of 3 metastases (interquartile range, 2.25 to 5) and received either 5-fluorouracil, leucovorin, irinotecan, and oxaliplatin (n = 4) or gemcitabine/nab-paclitaxel (n = 10). ³²P microparticles were implanted at a median 3.1 months from chemotherapy commencement. Local disease control rate at 3 months’ postimplantation was 100%. Primary tumor longest diameter decreased by 25% (interquartile range, –31.4% to –16.7%; P = .008), and serum cancer antigen 19-9 levels declined from 134 U/mL to 66 U/mL (P = .018). Local progression-free survival was 12.2 months (95% CI, 9.0-15.4 months) from chemotherapy commencement and 8.3 months (95% CI, 2.6-16.0 months) from ³²P microparticle implantation. Therapy was associated with improved quality of life, including global health status at 12 weeks’ postimplantation (P = .037). Median overall survival was 13.8 months (95% CI, 10.5-17.1 months) from chemotherapy commencement and 11 months (95% CI, 5.6-17.4 months) from ³²P microparticle implantation. No grade 4/5 acute toxicities were observed.

Conclusions

This first multicenter analysis of combined chemotherapy and EUS-guided ³²P microparticle implantation in mPDAC shows the potential clinical benefits of local tumor control in a cohort for whom outcomes are historically poor.