Researchers who treated a group of post-surgery bladder cancer patients
with the immunotherapy drug atezolizumab have found that patients whose
blood contained circulating tumour DNA (ctDNA), responded very well to the
treatment.
The study is presented today at the European Association of Urology Annual
Congress (EAU22),
in Amsterdam.
The research was part of a larger Phase III trial, IMvigor010, which looked
at whether giving atezolizumab for up to one year to patients following
bladder removal surgery improved the patients’ survival prospects, compared
to a group that received no further treatment after surgery but placed in
an observation group. Part of that trial involved patients’ levels of ctDNA
being measured after surgery, and during further treatment or observation.
Although the trial found no significant difference in overall survival
between the two groups in the intention-to-treat population, researchers
noticed that a subgroup of patients who were ctDNA positive showed a marked
improvement when they were given atezolizumab. These benefits included significantly
higher disease-free survival, and significantly higher overall survival,
than the observation group. This effect wasn’t seen in ctDNA negative
patients.
In addition, the researchers also found that patients who were ctDNA
positive, but subsequently changed to became ctDNA negative after treatment
with atezolizumab, ultimately had a particularly good prognosis.
ctDNA comprises fragments of DNA shed from cancerous cells and tumours that
are found in the bloodstream. Sometimes known as a ‘liquid biopsy’, it has
emerged as a promising, minimally invasive biomarker in clinical oncology,
but isn’t yet widely used as part of a standard detection and treatment
tool for any cancers. It involves tumour specific gene sequencing for every
patient, so is time-consuming and, at present, relatively expensive.
Professor Gschwend, Munich (DE), Chairman of the Department of Urology at
the Technical University of Munich, said: “We already knew that patients
who are ctDNA positive have a poor prognosis compared to those who are
ctDNA negative. But this is the first time we’ve been able to show that
with immunotherapy we can actually change the course of the disease
depending on a patient’s ctDNA status.”
He continued: “If we can prove that consequent drug activity is linked to
ctDNA status, and that high-risk patients will benefit, that could in time
change the standard treatment pathway – and ultimately bring down the
average cost of ctDNA analysis.”
Professor Morgan Rouprêt, Paris (FR), Chairman of the European Section of
Onco-Urology of the EAU (ESOU), said: “The field of personalised medicine,
using not only clinical but molecular indicators, is just around the
corner. So, analysing ctDNA is very interesting. It is relatively easy to
do with new technology and it means we can select a subset of patients who
are likely to respond.”
The next step will be the upcoming IMvigor 011 study, which has been
redesigned as a consequence of these results. With 500 participants, the
trial will further evaluate the use of ctDNA sampling, and will compare
atezolizumab against placebo in only ctDNA-positive patients, post-surgery.
Professor Rouprêt added: “Unlike in prostate cancer, where we can measure
PSA as a marker of the cancer, until now we haven’t had anything we can use
for bladder cancer. But these robust findings show that ctDNA has great
potential as a sophisticated tool to monitor patients and choose their most
effective treatment. The progress of the IMvigor 011 study will be watched
closely by specialists for a greater assessment of the use of atezolizumab
in bladder cancer patients.”
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