A new standard of skin cancer care
Posted on 13 March 2019
Immunotherapy has been used to treat skin cancer patients since the early 1990s, but recent innovations now make this unique technique the gold standard of care.
Usually, cancer medications concentrate on killing the disease. Chemotherapy, for instance, involves administering drugs that track down rogue cancer cells in the blood and lymphatic systems, before they can reach and affect vital organs.
Immunotherapy takes a different approach, says Dr Sze Wai Chan, a medical oncologist who practices at Sandton Oncology, and who is part of the multidisciplinary team of cancer treatment specialists at Mediclinic Morningside.
“Older forms of immunotherapy focused on simply boosting the immune system,” Dr Chan says. “We now know that is not effective in most cases.”
Typically, cancerous tumours are able to use proteins known as programmed death-1, or PD-1, and programmed death ligand-1 (PD-L1) to cloak themselves and evade the body’s natural immune response. Now, a new form of immunotherapy uses an antibody to prevent tumours from co-opting these proteins to their advantage – and allowing the body to target and kill the spread of cancerous cells as it should.
“Cancer hides inside the body by manipulating a key natural mechanism. We are correcting the mechanism,” says Dr Chan. “So we don’t need to boost the immune system, necessarily – if it is allowed to work properly, it is capable of eliminating anything foreign in the body, even cancer.”
A number of cancers are responsive to this new generation of immunotherapy medication, including lung cancer, certain colon cancers, bladder and kidney cancer. Researchers are still figuring out why immunotherapy does not help to treat breast cancer and prostate cancer effectively yet.
But one of them stands out. Up to 60% of advanced melanoma patients respond positively to anti-PD-1 immunotherapy – and the effects are remarkably long-lasting.
Dr Chan says patients with advanced melanoma usually have a very poor prognosis, as previous treatments were by and large ineffective. “In the past, the best-case scenario we could present to our stage 4 melanoma patients was a year’s survival. With this treatment, we now look at 12 years or longer.”
PD-1 and PD-L1 immunotherapy treatment are far more effective than traditional chemotherapy, says Dr Chan. “When we chase cancer directly, there is always the risk that some will be left behind. Even microscopic vagrant cells can cause the cancer to reoccur – it will almost always come back. But when we are able to unblock the mechanism that cloaks these cells and allow the immune system to attack them, recurrences are very rare.”
This immunotherapy treatment relies on a drug known as Pembrolizumab (or Keytruda®), an anti-PD-1 immunotherapy, which has been registered in South Africa since last year. The treatment involves a 30-minute infusion via a drip, every three weeks, for a total of two years.
Not all advanced skin cancer patients may qualify for this new treatment, Dr Chan warns. “To go through this cycle, of ‘unhiding’ the cancer and allowing the immune system to find and eradicate it, can take time,” she says. “As a normal turnaround time, we’re looking at around three months.”
Great news for patients: this treatment is non-toxic. “In comparison to any other kind of known cancer treatment, the toxicity profile of immunotherapy is very safe,” says Dr Chan. “Over 90% of our patients report no side-effects. They may feel tired or experience some mild joint pain or skin rash initially, but these are easy to manage. We find our patients can, in fact, work throughout treatment, with little disruption to their everyday lives.