Acne-like rash linked to effectiveness of new targeted cancer treatment – cetuximab

Acne is not a condition that anyone would welcome under normal circumstances, but an international study of a new targeted cancer treatment – cetuximab – has shown that patients who developed an acne-like rash responded better to the treatment than those who did not.

Professor Eric Van Cutsem told a news briefing today (Thursday 30 September) at the EORTC-NCI-AACR Symposium on Molecular Targets and Cancer Therapeutics that a trial, conducted in Belgium and the USA, had demonstrated that the more severe the rash the better the patients’ tumours had responded to the treatment and the longer was their median survival.

Professor Van Cutsem, who is head of the Digestive Oncology Unit and Professor of Medicine at University Hospital Gasthuisberg in Leuven, said 346 patients with advanced colorectal cancer were treated in the study in Leuven and other Belgian and U.S. centres.

All the patients had metastatic cancer and had failed to respond to at least two prior chemotherapy regimens, although all still had a reasonable quality of life, either being fully active or at least still able to carry out light work.

Cetuximab, also known as Erbitux, is a new targeted treatment – a monoclonal antibody designed to home in selectively on a protein called the epidermal growth factor (EGFR). EGFR is found on the surface of some cells and plays a role in regulating cell growth. Cetuximab interferes with the growth of cancer cells by binding to EGFR. It is approved by the Food and Drug Administration in the USA for use with the cancer drug irinotecan for colorectal cancer that has failed other treatments. It is also the first monoclonal antibody targeting EGFR to have gained marketing authorisation in Europe and is now being evaluated in first-line treatment of colorectal cancer, with promising results.

Professor Van Cutsem said that the acne-like rash was also a side effect of other EGFR inhibitors but it was not yet known why the rash occurred. This was still a subject of research.

"We saw independently reviewed partial tumour responses in 12% of patients and a median survival time of 6.6 months," he said. "In total, 87% of patients developed this acne-like rash. Of the 46 patients who did not develop a rash none had a tumour response and their median survival was only 2.1 months. Of the 142 with a grade one rash 8% had a tumour response and median survival was 4.9 months. Among the 141 patients who had a grade two rash the response rate was 18% and the median survival was 8.9 months and for the 17 patients with a grade three rash there was a 24% response rate and median survival was 13.0 months. Patients with a grade two/three rash had a highly statistically significant improvement in tumour response and overall survival compared to those with grade one or no rash."

Professor Van Cutsem said that the trend for improved response and survival was seen across all patients irrespective of their age, sex, EGFR status and their Eastern Cooperative Oncology Group (ECOG) rating, which measures how their disease affected daily living.

The research team are now undertaking a randomised study prospectively correlating the rash with tumour response. "Our results could be very important," he said. "While no rash does not mean no tumour response, it does mean there is a lower chance of response from these treatments and that may have future implications for treatments with EGFR inhibitors."