* Engineered antibody drug helps immune system fight cancer
* Early trials promising for lung cancer in smokers
* Lung tumours normally notoriously difficult to treat
By Kate Kelland
AMSTERDAM, Sept 29 An experimental Roche
drug that seems to work particularly well against lung
cancer in smokers may be a "game changer" for these normally
difficult-to-treat patients, researchers said on Sunday.
Presenting detailed data from an early-stage trial of the
drug, called MPDL3280A, in patients with a form of the disease
called non-small cell lung cancer (NSCLC), investigators said
what they had found was "great news for lung cancer patients".
Of 53 patients with NSCLC tumours treated with the drug, 23
percent saw their tumours shrink, according to results presented
at the European Cancer Congress (ECC) in Amsterdam.
But the most encouraging numbers were among smokers, where
the response rate was 26 percent compared with 10 percent of
patients who had never smoked, said Professor Jean-Charles Soria
of France's Institut Gustave Roussy, who led the study.
Lung cancer, which is usually caused by smoking, is
extremely difficult to treat successfully and once it has
started to spread to other parts of the body, it is incurable.
Roche's MPDL3280A is an engineered antibody that targets a
protein called PD-L1 - a defence mechanism that tumours use to
trick the immune system's T-cells into being inactive.
By blocking PD-L1, the drug allows the T-cells to wake up
and recognise the cancer, and then grow and multiply to attack
it more efficiently.
Rival drugmakers including Merck and Bristol-Myers
Squibb are developing immunotherapy drugs in a similar
class of drugs known as PD-1 inhibitors, also designed to
mobilise the body's own immune system to fight cancer.
Soria's team suspected that because lung tumours in smokers
have a higher rate of genetic mutations than tumours of lung
cancer patients who have never smoked, their immune systems may
be more likely to respond vigorously when PD-L1 is blocked.
So they drilled down into the data more closely, separating
out the 81 percent of the 53 patients who were smokers or former
smokers, and the 19 percent of them who were not.
"And bingo, this is the first targeted agent (drug) that
shows more activity in smokers than in non-smokers," Soria told
reporters in a briefing at the ECC.
Cora Sternberg, co-chair of the ECC's scientific committee
and an oncologist at the San Camillo and Forlanini hospitals in
Rome who was not involved in the study, said that although the
results were from very early-stage trials, they suggested the
drug was "definitely a game changer" in lung cancer.
Roche is also investigating MPDL3280A's potential for
treating a range of other cancers, including melanoma skin
cancer and kidney cancer, where it has already shown some
promise in early trials.
Cornelis van de Velde, an oncologist at Leiden University
Medical Centre in the Netherlands and president of the European
Cancer Organisation, said Soria's was an extremely important
study for NSCLC patients, who currently have very few treatment
options that make much impact on their disease.
"Hundreds of millions of euros have been spent chasing the
dream of immunotherapy for lung cancer patients, but with zero
results." he said. "These early findings..suggest that it has
the potential to open new therapeutic approaches."