Study of Radspherin® in Colorectal Carcinoma Subjects With Peritoneal Carcinomatosis Treated With HIPEC

Primary objectives:

* To investigate safety and toxicity of Radspherin® * To determine the maximum-tolerated dose (MTD) of Radspherin®, among the four suggested doses 1, 2, 4 and 7 MBq, as a single intraperitoneal (IP) injection and two repeated IP injections following cytoreductive surgery (CRS) and hyperthermic IP chemotherapy (HIPEC)

Secondary objectives:

* To establish a recommended dose of Radspherin® as a single IP injection and two repeated IP injections following CRS and HIPEC * To describe the biodistribution of Radspherin® * To examine the efficacy and clinical benefit of Radspherin® following CRS and HIPEC

Exploratory objectives:

* To explore the association of biomarkers with activity/clinical benefits, adverse events (AEs), or other effects associated with Radspherin® * To explore effects of catheter placement, Radspherin® administration technique, and infusion volume on the distribution of 224Ra labelled micro particles in the peritoneal cavity

The maximum number of subjects receiving Radspherin® in this study is 67. Subjects who discontinue prior to Radspherin® administration will be replaced.

Dose escalation cohorts: 3 - 24 subjects Repeated injection cohorts: 3 subjects Expansion cohort: up to 40 subjects