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 Histiocytes
are tissue based cells which are part of the normal immune system. There
are at least 4 well defined diseases involving abnormal histiocytic
proliferation recognized in dogs. These include cutaneous histiocytoma,
cutaneous histiocytosis,
systemic histiocytosis (SH), and
histiocytic sarcoma and malignant histiocytosis
(MH).
The malignant forms of canine histiocytic disease, histiocytic sarcoma
and malignant histiocytosis, occur with high incidence in Bernese
Mountain Dogs, Rottweilers, Flat Coated Retrievers, Golden Retrievers
and sporadically in many other breeds. Histiocytic sarcomas occur as
localized masses in spleen, lymph nodes, lung, bone marrow, skin and
subcutis, brain, and tissue of large joints. Histiocytic sarcomas can
also occur as multiple lesions in single organs (especially spleen), and
rapidly disseminate to involve multiple organs. Hence, disseminated
histiocytic sarcoma is difficult to distinguish from MH, which is a
multi-system, rapidly progressive disease in which there is simultaneous
involvement of multiple organs such as spleen, lymph nodes, lung, bone
marrow, skin and subcutis. Response of histiocytic sarcomas and MH to
chemotherapy is at best brief. It is vitally important that the correct
diagnosis by a pathologist experienced with the full spectrum of
histiocytic disease is obtained, so that it is clear which of these
histiocytic diseases has occurred in a given case. Only then can the
likely outcome be predicted and appropriate treatment (if one exists)
instituted. More detailed descriptions with images of the individual
histiocytic diseases are available at
www.histiocytosis.ucdavis.edu.
Elisabeth Zenger, DVM, PhD, Dipl American College of Veterinary Internal
Medicine, is conducting a funded clinical trial for dogs diagnosed with
histiocytic sarcoma, disseminated histiocytic sarcoma, or malignant
histiocytosis, a group of distinctive similar cancers making up the
histiocytic sarcoma complex. These malignancies are often only
recognized after clinical signs have appeared and the disease is
advanced. Histiocytic sarcoma complex diseases generally follow a rapid
(weeks to months) clinical progression to death or euthanasia. Response
to available chemotherapy has been at best brief. Novel
chemotherapeutics must be developed and investigated to fight these
devastating diseases. PG11047 is a drug designed to be of low toxicity
and an effective anticancer agent. This open label phase I/II trial
examines the safety, tolerability, and efficacy of PG11047, in canine
patients with naturally occurring histiocytic sarcoma complex disease.
This class of drugs holds great promise for treatment of canine
malignancies for which there are no other effective therapies.
All study procedures take place at Bay Area Veterinary Specialists,
14790 Washington Ave, San Leandro, CA. Included in the trial is cost of
the drug, administration, and all monitoring. Any one interested in
learning more about the trial is encouraged to contact Dr. Zenger at
510-483-7387. |
