In the run up to Mother’s Day, we explain how the breast cancer drug Kadcyla works and talk to a mother benefitting from this drug.
Kadcyla is a breast cancer drug capable of extending the life of women with secondary breast cancer by, on average, 5.8 months – although some patients have received years of good quality life from this drug. This means more time for women to spend with their families, doing the things they love. Despite how effective it’s proven to be, Kadcyla remains too expensive to be made routinely available on the NHS, although patients in England can access it through the Cancer Drugs Fund (which is not without its problems).
Laser guided missile
Kadcyla is essentially an upgraded version of the breast cancer ‘wonder drug’ Herceptin, so to explain how Kadcyla works, it’s sensible to first give some background on Herceptin. Herceptin is a type of targeted treatment known as a therapeutic antibody. When your immune system detects a foreign invader, such as a bacteria, it kick-starts a cellular programme to produce molecules called antibodies which help to fight the infection. These antibodies are little molecular detectors designed to specifically recognise and stick to parts of the invading bacteria.
Therapeutic antibodies act in the same way, except that instead of detecting bacteria they are designed to recognise molecules specific to diseased cells. In the case of Herceptin the antibodies are designed to recognise a molecule called HER2 – a cellular protein found in high amounts on the surface of HER2-positive breast cancer cells. When Herceptin sticks to HER2 it blocks the protein from sending signals into the cell which are telling it to grow and divide, effectively stopping the growth of tumours and even killing cancer cells.
Kadcyla is just like Herceptin except that strapped to each of these antibodies is a payload of chemotherapy. So just like Herceptin, Kadcyla seeks out cells with lots of HER2 on the surface, binds to the cells and drops a devastating blast of chemotherapy direct into the heart of the cell. It’s the laser-guided missile of the cancer drug world.
Kadcyla is currently offered to patients in the UK with HER-2 positive breast cancer that has spread or come back after treatment with Herceptin. As with all drugs it has been through a rigorous testing process to assess its safety and effectiveness compared to other available drugs. In 2012, an international study called EMILIA revealed that Kadcyla was able to extend life by an average of 5.8 months in women with HER2-postive secondary breast cancer compared to another popular treatment option.
The women in the EMILIA trial had all been treated with Herceptin and stopped responding to treatment before they were started on Kadcyla. This provides evidence that, as a ‘last-line’ option, Kadcyla can extend life for women with secondary breast cancer. But what about as a ‘first-line’ treatment? Is Kadcyla better than the current option of Herceptin plus a separate chemotherapy?
A study called MARIANNE was set up to answer these questions and found that in patients with secondary breast cancer who had not yet been treated, Kadcyla offered no additional benefit to receiving Herceptin plus chemotherapy. So we know that Kadcyla could provide months of extra life for those women with no other option, but we haven’t yet seen evidence that Kadcyla should replace Herceptin as a first-line treatment.
What really matters
Underneath all this data is the fact that Kadcyla offers women an average of almost six months extra life. This is an average, so whilst some women receive less benefit, others may go on to live far longer because of the drug. Importantly, the extra time given has been shown to be quality time, with patients experiencing fewer side effects so that they can do the things that matter the most to them.
Kelly is one of Breakthrough’s supporters. Just three weeks after she was diagnosed with breast cancer, she was told it had spread to her liver. Her doctors realised that her treatment just wasn’t working and so Kelly was offered to join a clinical trial of Kadcyla at the Christie Hospital in Manchester. As a mother to three sons, she was determined to do all she could to make sure she could spend as much quality time with her family as possible.
Kelly’s now been on Kadcyla for over two years. She told us:
I don’t suffer many side effects from the drug and I have met many more women who are being successfully treated with Kadcyla. I was absolutely devastated to find out that the drug has been deemed too expensive for NHS use and that so many women like me with young families would be denied the opportunity of a drug that has allowed me to see my youngest son go to school. I got married, enjoyed family holidays away including Disneyland Florida and a trip to Venice with my husband. You cannot put a price on those memories for me, my husband and my children.
A problem that won’t go away
Kelly’s reaction to the rejection of Kadcyla is one experienced by many breast cancer patients who have benefitted, or one day may need to benefit, from these drugs. Although Kadcyla has been deemed too expensive to be routinely available on the NHS, it is available to some patients in England on the Cancer Drugs Fund.
We have blogged before about the issues with the Cancer Drugs Fund and drug pricing, and it’s a problem which isn’t going away. Drugs are only going to get more expensive as they become more sophisticated. We must do something about it now so that all women in Kelly’s position can benefit from the best possible treatment.
Dr Matthew Lam is Breakthrough Breast Cancer’s Senior Research Officer