By Bill Berkrot
May 15 (Reuters) – An experimental leukemia treatment that
Roche Holding AG hopes will improve upon its
best-selling cancer drug Rituxan delayed disease progression
twice as long as chemotherapy, according to preliminary trial
data released on Wednesday.
Switzerland-based Roche aims to fend off cheaper competition
for Rituxan, which loses patent protection in Europe later this
year, threatening a product with nearly $7 billion in annual
sales.
Roche’s new drug in development, known as GA101 or
obinutuzumab, was given in conjunction with the commonly used
chemotherapy chlorambucil to previously untreated patients with
chronic lymphocytic leukemia (CLL) who also had other health
problems, such as heart disease. The treatment was compared
against that for patients who received the chemotherapy alone in
a late-stage clinical trial involving 589 people.
The combination of Roche’s drug plus chemotherapy led to an
86 percent reduction in risk of disease progression, according
to data from a scientific abstract released on Wednesday ahead
of the American Society of Clinical Oncology’s annual meeting
later this month.
Patients who received GA101 went 23 months on average before
their leukemia began to worsen, an interval known as
progression-free survival, or PFS. That compared with 10.9
months for chemotherapy alone, according to the latest available
data. Data showing the actual survival benefit will not be
available for some time, the company said.
Overall and complete response rates seen in the study
demonstrate the potential potency of the Roche drug.
The overall response rate was 75.5 percent compared with
30.2 percent of patients who responded to the chemotherapy
alone. Twenty-two percent of those who got GA101 had a complete
response, meaning the cancer was undetectable, whereas no
patients receiving chemo alone had a complete response.
“We have to wait for longer follow-up to comment on duration
of control of the disease,” Dr Valentin Goede, the study’s lead
investigator, said in an interview.
“Still, these are encouraging results,” said Goede, adding
that he believes progression-free survival for the Roche drug
was likely to improve.
HELPING THE IMMUNE SYSTEM DEFEND ITSELF
GA101 is an engineered antibody designed to better enable the
immune system to attack and kill B cells, from which many blood
cancers, such as CLL and lymphomas, originate. The drug, which
recognizes B cells on the surface of tumors, was engineered to
be more potent in attacking them than Rituxan.
Another arm of the trial, for which data will not be
available until late this year or in 2014, is testing GA101
directly against Rituxan. When Rituxan plus chemotherapy was
compared to chemotherapy alone, it showed progression free
survival of 15.7 months and an 8.3 percent complete response
rate.
If the new drug shows clear superiority over Rituxan in the
head-to-head portion of the trial, Roche would be able to defend
the multibillion-dollar franchise against cheaper biosimilar
versions of Rituxan when they emerge. Roche also has full rights
to GA101, while it shares Rituxan revenue with Biogen Idec
.
Goede, from University Hospital of Cologne in Germany, said
the trial was important because it was the first large Phase III
CLL study of the type of patient doctors most typically see –
older with additional health problems.
It is estimated that 15,680 Americans will be diagnosed with
and 4,580 will die of chronic lymphocytic leukemia in 2013,
according to the National Cancer Institute.
The new medicine did have a far higher incidence of
neutropenia, or reductions in white blood cell count, than
either Rituxan or chemo alone. However, Goede called the safety
profile acceptable because the neutropenia did not lead to
infections or fever.
There were also infusion-related reactions seen with the
first dose of GA101 that were not seen with chemotherapy. That
was managed by splitting the first dose of the drug over two
days, researchers said.
Goede noted that there had been a similar issue in early
clinical trials of Rituxan. “This is a problem that can be
fixed,” he said.
