14020 Background: Mucinous peritoneal carcinomatosis is most commonly associated with primariy tumors of the appendix and colon. Typically, spread remains confined to the abdominal cavity. Imaging assessment of these mucinous lesions is difficult, and tumor markers (CEA and CA19.9) are often used as a surrogate for extent of disease. Patients (pts) often undergo surgical debulking, sometimes coupled with intraperitoneal (IP) drug delivery, but recurrence is common. Since mucin genes are regulated by EGFR, our two institutions initiated this study.
METHODS
Between Sept 2004 and Dec 2005, weekly cetuximab (loading 400 mg/m2 on first dose, followed by 250 mg/m2/week thereafter) was given to 20 pts (4 men, 16 women): 17 of appendiceal origin were entered a median 3 y (6 m-7 y) after diagnosis; 3 were unknown primaries 24, 23, and 2 m after diagnosis. Prior treatment included surgery (18), systemic (17), and intraoperative (4) or subsequent IP therapy (2).
RESULTS
Pts received a median of 12 doses (0-51) of cetuximab. No major objective responses were observed; transient > 25% decreases in CEA and CA19.9 were noted in 4/19 pts; markers were never elevated in 1. Stable disease was best response in 3 of 15 evaluable (5 too early). The most common toxicities, as expected, were skin rash, dryness, and nail fragility. Hypersensitivity reactions in 2 patients did not preclude repeated dosing with premedications. The median time to progression from the start of treatment was 3 m.
CONCLUSIONS
Brisk accrual by two institutions in this rare clinical entity is noteworthy. In this heavily pretreated population, transient decrease in tumor markers and time on study with stable disease were encouraging, prompting plans for a future study of cetuximab with the addition of systemic irinotecan. [Table: see text].