For people diagnosed with advanced pancreatic cancer, the outlook is about as grim as it gets: the average patient won't live longer than a year.

But a new study involving a targeted drug therapy has demonstrated it may be possible to significantly slow its spread, with a third of patients receiving the medication still alive 2 years into a clinical trial, a researcher reported on Sunday.

The trial specifically looked at patients with BRCA gene mutations, which are inherited and are known to increase the chances of getting pancreatic, ovarian, prostate, and breast cancer—the reason why actress Angelina Jolie had a preventative double mastectomy.

The mutation affects the body's ability to repair damaged DNA, which can result from a number of factors ranging from excess sunlight to exposure to asbestos.

"Normal cells may be able to repair it, but cells that have the mutation cannot repair this damage, and they then start to grow abnormally because they have damage in their DNA," lead author Hedy Kindler, an oncologist at the University of Chicago Medical Center, told AFP.

Enter so-called "PARP inhibitors" which act somewhat counter-intuitively by blocking a protein, PARP, that helps damaged cells repair themselves. Since cancer cells with BRCA gene defects already have a poor repair system, targeting them using a PARP inhibitor worsens the damage and ultimately kills them.

The trial screened more than 3,300 people with pancreatic cancer, identifying around 250 with the faulty gene. They then randomly assigned the drug, known as olaparib, to a portion of them and a placebo to another group.

Olaparib, which is sold by Merck as "Lynparza," was found to reduce the risk of disease progression by 47% compared to the control group. Those patients who received olaparib had their disease under control for almost twice as long (7.4 months vs 3.8 months) as those patients who received the placebo—a measure known as median progression-free survival.

Tumor shrinkage

"Those patients whose tumor shrank with the olaparib, which was about a quarter of them, their tumor shrinkage was maintained for more than 2 years," added Kindler, who presented the findings at the annual meeting of the American Society of Clinical Oncology.

"The whole idea is...you can transform an otherwise deadly prognosis into a potentially chronic disease, at least for a while, and [...] keep it under control."

Suzanne Cole, an oncologist at Southwestern Medical Center, who was not involved with the study, said it represented a "huge step forward for patients with metastatic pancreatic cancer." She added that now the effectiveness of the medication had been identified, it was important for clinicians to screen patients for the mutation to identify those who could benefit from the therapy. Kindler cited the case of a patient who watched his brother die from the disease before learning he himself had the cancer. He was found to have the BRCA mutation and placed on the trial.

"Every single time we do a CT [computed tomography] scan, his tumor is smaller and smaller," said Kindler. "He takes a pill twice a day, and two and a half years later, he's still around. He's leading a normal life."