Experimentally induced liver metastases from colorectal cancer can be prevented by mononuclear phagocyte-mediated monoclonal antibody therapy.
OBJECTIVE
Development of liver metastases is a frequent complication in patients with colorectal cancer (CRC), even after successful resection of the primary tumor. As such, post-operative adjuvant therapies that aim to eliminate residual disease after surgery may improve patient outcome.


METHODS
We used a colon carcinoma liver metastases model, in which CC531s colon carcinoma cells are injected into the portal circulation by a surgical procedure. As injected tumor cells are arrested in the liver, this model is suitable for investigating the interaction of tumor cells with the liver microenvironment. By administering tumor specific monoclonal antibodies (mAb) directly post-operatively, we were able to determine the effect of antibody therapy on eradication of arrested tumor cells and subsequent liver metastases outgrowth.


RESULTS
We showed that post-operative treatment with tumor specific monoclonal antibodies (mAb) prevents liver metastases outgrowth. Antibody-dependent phagocytosis (ADPh) was the main mechanism involved, as enhanced uptake of tumor cells by innate mononuclear phagocytes in the liver was observed after mAb therapy. Furthermore, Kupffer cells (KC) were identified as the most prominent effector cells, as depletion of KC abolished therapeutic efficacy. This was partly compensated by monocytes when animals were treated with a high mAb dose, but monocytes were unable to phagocytose tumor cells when rats were treated with low mAb doses.


CONCLUSIONS
The finding that KC and monocytes can eliminate tumor cells through ADPh has important and promising clinical implications for designing new adjuvant therapies for patients undergoing CRC resection.
van der Bij
Gerben J
GJ
Department of Surgical Oncology, VU University Medical Center, Amsterdam, The Netherlands.
Bögels
Marijn
M
Otten
Marielle A
MA
Oosterling
Steven J
SJ
Kuppen
Peter J
PJ
Meijer
Sybren
S
Beelen
Robert H J
RH
van Egmond
Marjolein
M
D000818:Animals; D000911:Antibodies, Monoclonal / Q000627:therapeutic use*; D015179:Colorectal Neoplasms / Q000188:drug therapy* / Q000473:pathology / Q000601:surgery; D003131:Combined Modality Therapy; D006801:Humans; D007963:Leukocytes, Mononuclear; D008113:Liver Neoplasms / Q000188:drug therapy* / Q000517:prevention & control / Q000556:secondary / Q000601:surgery; D008114:Liver Neoplasms, Experimental; D051379:Mice; D010586:Phagocytes; D010587:Phagocytosis; D016896:Treatment Outcome
D000911:Antibodies, Monoclonal