Sometimes two cancer drugs are better than one. The length of time that a breast cancer treatment continues to work could be extended by delivering it alongside a lung cancer medicine that stops tumour cells from developing resistance.
So far the strategy has been shown to work in mice and on cancer cells in the lab – but the researchers say it should move relatively quickly into tests on women with breast cancer, because both medicines are already in use.
The breast cancer medicine, called palbociclib, is one of the newer “targeted” cancer drugs that work by interfering with a specific tumour molecule rather than just killing all rapidly dividing cells like chemotherapy does. In this case it blocks the function of two proteins that promote cell division. But breast cancers usually develop mutations that mean they become resistant to this treatment within a few months and start growing again, says Paul Workman of The Institute of Cancer Research in London.

Combination therapy

His team found that cancer cells do this by turning on an alternative molecular pathway to cell division. This can be blocked by the lung cancer medicine, called crizotinib. Tumours implanted in mice treated with the combination grew at about two-thirds the rate of those in mice given either of the treatments separately.
Although palbociclib is so far only used against breast cancer, the researchers found that the two-drug combo was also effective against other kinds of tumours, including those from the lungs and bowel, suggesting the strategy could be applied more widely.
“Because we already know they’re safe and effective we can proceed more quickly to a combination study,” says Workman. “We would be hoping to start trials in patients in the next 18 months.”