Iain Grant cLBT Case Study

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Iain Grant BVSC MRCVS Dip ACVIM
(medical oncology), University of Glasgow, shares his experiences with cLBT

Ernie was a 5 year 7 month old male neutered Jack Russell Terrier (5.7kg) examined at his primary vet practice with a history of rectal prolapse. Upon referral and a full clinical work up, eosinophilic colitis was identified histologically on mucosal biopsies from the rectum.

Unexpectedly, high grade T cell lymphoma was also diagnosed based on a fine needle aspiration biopsy and flow cytometry carried out on a sample collected from a single enlarged abdominal lymph node. This was identified on routine ultrasound examination of the abdomen.

Ernie was assigned a stage 1 status for his disease. His owner declined surgical removal of the lymph node for further histological assessment.

It was decided to treat Ernie in practice with a discontinuous, multidrug chemotherapy protocol (Madison-Wisconsin protocol) delivering two cycles of treatment over 9 weeks. Due to the occult location of disease we elected to utilise the cLBT in this case for several reasons:

• A baseline cLBT score prior to starting treatment could make the clinical diagnosis of lymphoma more robust (in the absence of a histological diagnosis) correlating with the cytological and ultrasound imaging findings.

• A reduction in the cLBT score could help to confirm complete disease remission in response to therapy, which would be verified by repeat abdominal imaging.

• Once remission had been achieved, the cLBT could be used as a useful monitoring tool for the ongoing remission status of Ernie without the expense and requirement for serial repeat abdominal imaging due to the occult location of his measurable disease. A rising cLBT score would indicate the need for repeat abdominal ultrasound to examine for disease relapse although it was acknowledged that the score could climb in advance of measurable lymphadenopathy.

The baseline cLBT score was 2.03 (borderline score).

After 4 weeks of chemotherapy treatment, the cLBT was 0.19 (typical for a patient free from lymphoma). An abdominal ultrasound was repeated and this indicated resolution of the previously documented lymphadenopathy.
On completion of therapy (week 9), the cLBT score was 1.15 (typical for a patient free from lymphoma) and a final abdominal ultrasound scan identified ongoing disease remission.

Eight and 16 weeks following completion of therapy (the last test taken to date) the cLBT score remained level at 1.15.

Ernie remains clinically well and the owner and veterinarian are really happy with the ease and convenience of patient monitoring using this diagnostic test.

Although the initial score was only in the suspicious range, the burden of disease was low (only one node affected) and this raises the interesting question of how the stage of disease may affect the cLBT result. The dramatic drop in the cLBT in response to therapy, confirmed ultrasonographically as a complete remission (CR), would validate the usefulness of the test in this case to indicate a treatment response. The results of the follow up monitoring tests are in the mid-range for patients free of disease and in ongoing remission.