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When Jimmy Carter was diagnosed last year with melanoma that had spread to his brain, many people feared the worst for the oldest living US president.
Yet four months after making his condition public, he revealed that the cancer had disappeared. By March this year, doctors were confident enough to give him the all-clear. “So I’m not going to have any more treatment,” he told the Sunday school class he teaches in his home town of Plains, Georgia.
Mr Carter, 91, is one of the latest beneficiaries of a new drug type which many scientists, medics and pharmaceuticals executives believe is destined to transform the treatment of cancer. Until recently, advanced melanoma would have been a near-certain death sentence. That has begun to change since the arrival of Keytruda, the drug by Merck of the US given to Mr Carter, and a rival product, Bristol-Myers Squibb’s Opdivo.
Both are so-called PD-1 checkpoint inhibitors, which work by disabling the mechanism used by cancer to evade the immune system. Robbed of this defence shield, tumours are exposed to attack by disease-fighting T-cells.
These are among the first of a category of “immunotherapies” which use varied techniques to help the body fight back against cancer. Some researchers have likened them to the antiretroviral drugs which have turned HIV into a manageable chronic condition.
“The excitement is warranted because of the extent to which we are seeing very durable responses — people with very advanced cancers surviving for many years,” says Sir Harpal Kumar, chief executive of Cancer Research UK.
This is good news for patients and investors. Cancer immunotherapies are forecast to generate tens of billions of dollars in revenues over coming years, helping the industry rebound from recent patent expiries on many older drugs. Keytruda and Opdivo are, together, generating more than $300m of sales every month and several similar products are nearing market.
Researchers caution against seeing “immuno-oncology” as a miracle cure. Keytruda and Opdivo have so far been used mainly against melanoma and a type of lung cancer — and less than a third of people with those conditions respond to treatment. “There are still a number of very significant questions,” says Sir Harpal. “The most important is why only a relatively small population benefits. How can we pinpoint who will benefit and who won’t and why?”
Pharma companies believe that they are starting to find answers. Data to be published at the annual meeting of the American Society of Clinical Oncology, which starts today in Chicago, are expected to show progress in extending checkpoint inhibitors into a wider range of cancers. Researchers are experimenting with drug cocktails that combine immunotherapy and other approaches with the aim of raising response rates.
The number of people killed by cancer every year worldwide
“We are at the beginning of the immuno-oncology era and only starting to understand the complexities of the tumour ecosystem,” says Chris Boshoff, head of early development in immuno-oncology for Pfizer. “Finding the right combinations is going to be key.”
By 2025, most cancer patients will receive some kind of immunotherapy as part of their treatment in much the same way as chemotherapy is standard today, according to Mr Boshoff.
Paul Workman, chief executive of the UK-based Institute of Cancer Research, does not dispute such forecasts but questions whether it is sensible for so many drug companies, including Roche, AstraZeneca and Pfizer, to be developing checkpoint inhibitors to rival Merck and Bristol-Myers Squibb.
“I’m genuinely excited [by immuno-oncology] but the pendulum has probably swung too far,” he says. “A certain number of companies competing for the best PD-1 is good but do we need 20?”
Immunotherapy is not the only scientific breakthrough improving patient prospects. Just as important could be advances in diagnostic technology leading to earlier, more accurate detection. “Liquid biopsies” which can identify DNA shed by tumours into the bloodstream could make it possible to spot cancer long before symptoms show.
Among the pioneers of this technology is the Californian company Grail, spun-out of genomic sequencing group Illumina and backed by investors including Bill Gates and Amazon founder Jeff Bezos. Illumina president Francis deSouza says better diagnostics can save lives and money. “Treating cancer at stage one is much cheaper than treating it late.”
Containing the cost of cancer is an increasing problem for health systems around the world. The disease kills some 8m people a year worldwide — 13 per cent of all deaths — with cases forecast to grow by 70 per cent over the next 20 years, says the World Health Organisation.
Cost of US government ‘cancer moonshot’ search for cures
Much of the increase will come among the rapidly ageing populations of newly-industrialised countries such as China.
Health activists complain that the benefits of immunotherapy will remain out of the reach of most patients around the world because of their high cost. Keytruda and Opdivo are both priced at about $12,500 per month in the US.
Prof Workman says new approaches to research and development are needed to improve affordability. He highlights the approval last year of Tagrisso, an AstraZeneca drug which took two and a half years from first clinical trials to launch, compared with the decade or more the process has usually taken.
Tagrisso is targeted at lung cancer patients with a particular genetic mutation, allowing for smaller, faster trials than those for one size-fits-all medicines. “This opens the potential to fundamentally change the economics of R&D,” says Prof Workman.
The US government this year launched a $1bn “cancer moonshot” programme to support the push for new approaches. The project is spearheaded by US vice-president Joe Biden, whose son, Beau, died last year from brain cancer — a reminder of how big a threat the disease remains even as Mr Carter’s survival demonstrates progress.