Chemoresponse Assay in Head and Neck Cancer Patients: A Three-Year Follow Up

The majority of patients with advanced head and neck cancer receiving chemotherapy show partial response or frank resistance. Therefore, assessing the individuals' tumour reactivity to the eligible chemotherapeutic compounds carries the potential of personalizing the patient treatment and minimizing ineffective regimens which lead to excess toxicity and cost, treatment delays and possibly causing the tumour to be cross resistant to additional drugs.

To determine the effectiveness of a phenotypic chemoresponse assay in predicting response to chemotherapy in a retrospective series of head and neck cancer patients whose tumour specimens had been tested with ChemoFx assay (Precision Theraputic Inc.).

Twenty-two tumour specimens were submitted to Precision Theraputics Inc. for chemoresponse testing, all of which have been histologically confirmed as squamous cell carcinoma of the head and neck. Selection of treatment was at the discretion of the treating physician and the results of the assay were not used to determine the therapy. A portion of the patients' solid tumour was established in primary culture, then exposed to increasing doses of different chemotherapeutic agents. The resultant cell counts in the treated wells were used to indicate the tumours' response to the agent and based on the dose response score curve, the test was scored as "responsive," "intermediate response," or "non-responsive."

Of the 22 tumour samples submitted, 16 (72.7%) showed adequate cell yield in cultures and subsequently underwent in vitro chemoresponse assays and are reported in this study. Of the 16 cases reviewed, 5 were excluded due to inadequate follow up. A predictable response assay was either a good response to chemotherapy in patients whose tumour specimens showed sensitivity to the chemotherapeutic agents or failure in patients whose tumours showed either intermediate response or non responsiveness to the chemotherapeutic agent/agents. Of the 11 patients reported in this study, nine showed a predictable chemoresponse assay (81.8% predictability of effective treatment). Three patients had a predictable good response and six who failed their chemotherapy regimen within six months of treatment and their chemoresponse assay showed an inadequate response to the chemotherapeutic agents they were treated with. At three years follow up, all patients who had a predictable poor response succumbed to their disease except one, whose test showed intermediate response.

While the current report has its limitation, we conclude, based on our findings, that chemoresponse assays may be useful adjuncts in the guiding the selection of chemotherapeutic agents in patients with head and neck cancer.