It's the bane of most teenagers'
lives, but acne may soon be a welcome development for
colorectal cancer patients being treated with the monoclonal
antibody cetuximab. On September 30 at the Symposium on
Molecular Targets and Cancer Therapeutics in Geneva, Dr
Eric Van Cutsem of the University Hospital Gasthuisberg
in Leuven, Belgium, reported that the effectiveness of
cetuximab strongly correlates with the severity of the
commonly-occurring acne-like skin rash in patients whose
advanced form of colorectal cancer had spread to other
parts of their bodies.
Cetuximab is a monoclonal antibody
marketed by ImClone Systems Incorporated as Erbitux.
The compound targets a surface-located, growth regulating
protein called epidermal growth factor receptor produced
by many cells including cancerous ones. By binding to
the factor, cetuximab is thought to muck up the growth
machinery of the cancer cells.
The 346 colorectal cancer patients
treated in Belgium, as well as at participating centres
in the US, had poor chemotherapy track records. They
were all unsuccessfully treated at least twice with
an armada of cancer fighting drugs including irinotecan,
oxaliplatin and fluoropyrimidine. Despite these setbacks,
the patients were fully active or at least capable of
light labour when they participated in the trial.
The patients were given a 400mg/m
starting dose of cetuximab, and then treated with weekly
doses of 250mg/m until the disease progressed or the
drug's side effects became unacceptable.
Overall, an at least partial response
to cetuximab was apparent in 12% of the patients, who
survived for a median of 6.6 months. As for side effects,
87% percent of the patients developed an acne-like rash.
The presence or absence of the
rash was unimportant in terms of tumour response. However,
the severity of the rash was linked to cetuximab's effectiveness.
The 141 patients with a grade 2 rash and the 17 patients
with a grade 3 rash had median survival times of 8.9
and 13.0 months, respectively, as compared to the 142
patients with a grade 1 rash, who had a median survival
time of 4.9 months, and the 46 rashless patients whose
median survival time was only 2.2 months.
This "clear and important finding"
was independent of age, sex and how much or how little
the patient's daily life was affected by cancer, according
to Dr Van Cutsem.
"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 [epidermal growth
factor receptor] inhibitors," remarked Dr Van Cutsem
at a conference news briefing.
The explanation for the link between
a more severe rash and a better outcome from cetuximab
treatment will have to wait for the results of a recently
initiated randomized prospective study.
Sadly, this latest good news for
Erbitux comes too late for Martha Stewart, who only
days ago began her six-month prison sentence for alleged
improper trading activity with ImClone's stock.
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