An open-label, single-arm study assessing safety and efficacy of panitumumab in patients with metastatic colorectal cancer refractory to standard chemotherapy.
BACKGROUND
A phase 3 study demonstrated that panitumumab, a human monoclonal anti-epidermal growth factor receptor antibody, significantly prolonged progression-free survival versus best supportive care (BSC) in patients with chemorefractory metastatic colorectal cancer.


METHODS
This open-label extension study evaluated panitumumab monotherapy in BSC patients with radiographically documented disease progression in the phase 3 study. Patients received panitumumab 6 mg/kg every 2 weeks. The primary end point was safety; efficacy was also evaluated.


RESULTS
One hundred and seventy-six patients were randomly assigned to the BSC arm of the phase 3 study received >/=1 panitumumab dose in this extension study. Panitumumab was well tolerated. The most frequent treatment-related adverse events were skin toxic effects. Three (2%) patients had a grade 4 treatment-related adverse event. There were no infusion reactions. One (0.6%) patient had a complete response; 19 (11%) patients had a partial response; and 58 (33%) patients had stable disease. Median progression-free survival time was 9.4 [95% confidence interval (CI): 8.0-13.4) weeks. Median overall survival time was 6.3 (95% CI: 5.1-6.8) months. Anti-panitumumab antibodies were detected in 3 (4.2%) of 71 patients with a post-baseline sample.


CONCLUSIONS
These findings are comparable to those from the phase 3 study and support panitumumab monotherapy for chemorefractory colorectal cancer.
Van Cutsem
E
E
Digestive Oncology Unit, University Hospital Gasthuisberg, Leuven, Belgium.
Siena
S
S
Humblet
Y
Y
Canon
J-L
JL
Maurel
J
J
Bajetta
E
E
Neyns
B
B
Kotasek
D
D
Santoro
A
A
Scheithauer
W
W
Spadafora
S
S
Amado
R G
RG
Hogan
N
N
Peeters
M
M
D000230:Adenocarcinoma / Q000188:drug therapy / Q000401:mortality / Q000628:therapy*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000911:Antibodies, Monoclonal / Q000009:adverse effects / Q000627:therapeutic use*; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D015179:Colorectal Neoplasms / Q000188:drug therapy / Q000401:mortality / Q000628:therapy*; D018450:Disease Progression; D018572:Disease-Free Survival; D003875:Drug Eruptions / Q000209:etiology; D019008:Drug Resistance, Neoplasm; D066246:ErbB Receptors / Q000037:antagonists & inhibitors* / Q000276:immunology; D005260:Female; D006801:Humans; D007167:Immunotherapy / Q000009:adverse effects / Q000706:statistics & numerical data; D008297:Male; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors* / Q000276:immunology; D000077544:Panitumumab; D016879:Salvage Therapy / Q000706:statistics & numerical data; D016019:Survival Analysis