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 CANCER specialists are eagerly awaiting the large-scale trial of a powerful new drug that spells hope for some women stricken with breast or ovarian cancer.
It is expected to start soon, given the drug’s good showing in early trials. The new class of drugs, called parp inhibitors, targets cancers in women who have a certain mutation in their genes, for whom conventional treatment has failed.
The results of an early-phase trial involving more than 100 women in Australia, Europe and the United States show up to a third of patients with ovarian cancer, and 41 per cent of those with breast cancer, seeing signs of improvement. They also suffered few side effects, according to the study, published in The Lancet journal last month.
The trial was conducted at 16 centres for breast cancer patients and 12 for ovarian cancer patients. All had undergone conventional treatment, half having three or more attempts with chemotherapy, but their cancers were still progressing.
The most frequent cancer in women is of the breast, affecting almost one in three women with cancer. Ovarian cancer is usually discovered late and tends to be deadly. More than 200 new cases emerge each year with almost half found after it has spread to other parts of the body.
Oncologists have been following the progress of the parp inhibitors with great interest, as it could give them a new weapon to help these women when conventional treatments fail. A drug could be available in as little as two to three years.
In general, about 10 per cent of women with ovarian cancer and 5 per cent with breast cancer carry these BRCA1 and BRCA2 gene mutations.
Dr Tay Eng Hseon, who specialises in cancer in women’s reproductive organs, said the new drug is particularly promising as the mutations are more often found in younger cancer patients “in the prime of their lives”.
Dr Tay, of Thomson Women Cancer Centre, said “ovarian cancers are highly lethal”, so the new drug could make a difference in patients’ chances of survival.
Dr Mikhail Hartman, a breast cancer surgeon at the National University Hospital, agreed that the new drug was “potentially very big”. “It is a new mechanism ...a targeted drug with thus far limited side effects and a fairly big response.”
Cancers are not homogenous, even when they attack the same organ: one reason not everyone benefits equally from standard treatments. In the past decade, research focus has switched to targeted treatments – customising treatments for a specific type of cancer or patient.
By identifying the patients who would more likely benefit from a certain treatment, doctors no longer have to offer all patients expensive treatments on a trial and error basis.
Adjunct Associate Professor Lee Soo Chin of the National University Cancer Institute called the new drug “an important new class of anti-cancer drugs”. She added that the development of such drugs “illustrates the future direction of developing anti-cancer drugs for ‘niche’ group of patients rather than to develop drugs for large unselected populations”.
Some years ago, a targeted drug called Herceptin was launched. It could help one in four women with breast cancer.
KK Women’s and Children’s Hospital’s (KKH) Dr Lim Sheow Lei said that while the parp inhibitor is not a cure, it does offer patients with the BRCA1 and BRCA2 mutations “an extra weapon”. It might even serve as cancer prevention medication for people with the mutation.
Associate Professor Hong Ga Sze who heads KKH’s breast unit, was more cautious, saying the drug will become “important” only after it passes large-scale Phase III trials where it is pitted against current treatments. Nevertheless, he said, the hospital would be keen to participate in such trials.
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