Vaccine-associated Feline Sarcoma Symposium held at AVMA Convention

The Vaccine-Associated Feline Sarcoma Symposium was held on Saturday, July 25, 1998 at the 135th Annual Convention of the American Veterinary Medical Association. Representing the AVMA Council on Research, Dr. William Inskeep introduced the symposium which was co-sponsored by the Vaccine-Associated Feline Sarcoma Task Force (VAFSTF) and Arm & Hammer Division of Church & Dwight Co. Inc. The symposium featured speakers representing each of the four subgroups of the Vaccine-Associated Feline Sarcoma Task Force.

Speaking for the pathology/epidemiology subgroup, pathologist Dr. Mattie Hendrick from the University of Pennsylvania School of Veterinary Medicine presented a historical overview and reviewed current research involving the etiopathogenesis of vaccine-associated sarcomas. Dr. Hendrick briefly described her own studies of tissue growth factors and growth factor receptors, and their potential role in the formation of tumors at vaccination sites.

Dr. Philip Bergman, a researcher at the M. D. Anderson Hospital in Houston, Texas, represented the molecular biology/etiology subgroup. Dr. Bergman described several mechanisms believed responsible for cancer formation, including activation of oncogenes, "turning off" or mutation of tumor suppressor genes, and disruption of apoptosis (programmed cell death). Fibrosarcomas, believed to result from neoplastic transformation of fibroblasts, are among the most commonly-diagnosed vaccine-associated sarcomas. However, other types of sarcomas are associated with vaccination, and Dr. Bergman conjectures that neoplastic transformation of primitive mesenchymal cells may be responsible.

Speaking for the treatment subgroup, Dr. Guillermo Couto of the Ohio State University College of Veterinary Medicine reviewed current treatment options. Dr. Couto noted that poorly-differentiated sarcomas appear to be more responsive to chemotherapy than are more well-differentiated tumors. He also emphasized the importance of early diagnosis and the need for wide surgical excision of vaccine-associated tumors from the outset; successive attempts at complete tumor removal invariably are less successful.

Chairperson of the education/communication subgroup, Dr. James Richards of the Cornell Feline Health Center detailed the communication methods employed to raise awareness of vaccine-associated sarcomas. Information about vaccine-associated sarcomas and initial vaccination guidelines were distributed through a variety of veterinary publications. Once a client education brochure was developed and made available to veterinarians, efforts were made to make cat owners aware of the issue. The presentation of accurate information to the general public has minimized the need to correct inaccurate, misleading, or alarmist information in the news media.

Finally, Dr. Robin Starr, chairperson of the VAFSTF, discussed the multi-organizational task force as a model for problem-solving in veterinary medicine. She also reported that $95,000 in additional funding has been received since March 1998. The additional contributions bring the total to 93% of the task force's first-year goal of $250,000, and enable the funding of all six studies approved in 1997. (For more complete information about the studies, see the January 15, 1998 issue of the Journal of the American Veterinary Medical Association, pp. 162-163.)

The Task Force is pleased to acknowledge the contributions made by the following entities:

Organizations:

AAHA Foundation $50,000

AVMA 50,000*

American Association of Feline Practitioners 25,000

Cornell Feline Health Center 10,000

Veterinary Cancer Society 5,000

Individual: 500

Subtotal $140,500

Manufacturers:

Fort Dodge Animal Health $25,000

Pfizer Inc., Animal Health Group 25,000*

Intervet, Inc. 10,000

Bayer Animal Health 10,000

Merial Animal Health 10,000*

Schering/Plough Animal Health 10,000*

Synbiotics Corp. 2,500

Subtotal $92,500

Grand Total $233,000

* Contributions made since March '98

The VAFSTF selected and funded the following six studies from the many excellent proposals submitted. Six-month updates are available on those funded prior to March.

An exhaustive epidemiologic study of vaccine-associated sarcomas and putative risk factors is being led by Dr. P. Kass of the University of California. In the six-month update, Dr. Kass reports that almost 800 patients are presently enrolled in the study. Dr. Kass provided a map that shows vaccine-associated sarcomas have been identified in every geographic location from which sufficient numbers of cases have been submitted.

Dr. S. Kanjilal of the University of Minnesota heads a team striving to accurately determine disease-free margins and predict outcomes of patients with vaccine-associated sarcomas. The team is establishing a tissue bank, investigating the role of the p53 tumor suppressor gene and the c-myc protooncogene, and testing the hypothesis that multiple genetic alterations are involved in the genesis of vaccine-associated sarcomas. In the six-month update, Dr. Kanjilal reports that her group has collected thirteen tumor sets, optimized PCR amplification of the p53 gene, and developed procedures for collection and establishment of cell lines.

In a second etiology study, Drs. MacEwen of the University of Wisconsin and Radinsky of MD Anderson Cancer Center are leading a multi-center investigation of growth factor regulation of malignant cells. If growth factors are shown to play a role in tumor formation, it is hoped that the factors or their receptors may serve as targets for therapeutic intervention. In the six-month update, Dr. MacEwen reports that his group has established cultures of cells collected from a number of vaccine-associated sarcomas, and is beginning to compare the effects of growth factors on malignant cells and normal feline fibroblasts.

In a third etiology study, Dr. M. Hendrick and others from the University of Pennsylvania are studying various types of lymphocytes found at vaccine-associated sarcomas, and the role they may play in tumor formation. They are also conducting molecular analyses of growth factors and their receptors, and of the protooncogenes sis, fms, and jun. If the growth factors, oncogenes, or lymphocytes are important, they may be potential targets for therapeutic intervention.

In a study to evaluate treatment, Dr. D. Vail and others at the University of Wisconsin are comparing the efficacy of doxorubicin and stealth liposomal doxorubicin in a multi-center randomized clinical trial. In the six-month update, Dr. Vail reports that to date his group has entered 30 post-surgical cases and 14 primary (pre-surgical) cases into the study.

In an another treatment study, Dr. A. Hohenhaus from the Animal Medical Center is comparing the efficacy of radiation therapy with and without a radiosensitizer. The radiosensitizer, a hemoglobin-based oxygen carrier, is hoped to improve tumor oxygenation, thus enhancing tumor cell kill rate after radiation therapy. She is also assessing 24-month outcomes after surgical excision with and without carboplatin, a chemotherapeutic agent.

Dr. James R. Richards

Director, Cornell Feline Health Center

Chairperson, Education/Communication Subgroup, VAFSTF

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