It is common for my patients to bring along news reports about the latest cancer treatments, or press releases extolling a pharmaceutical company’s newly-approved oncology drug that might extend life by a few weeks or months. After all, they have a vested interest in their disease and want to make sure that their oncologist is up to date.
I invariably take the clippings and thank them. “Only time will tell how well this may work,” I usually reply. They get the message: beware of getting too excited by any hype you read in the news. The reality is not usually so rosy.
In truth, who can blame people when stories with a positive spin raise their hopes?
Over the last two weeks alone, the public was abuzz about the reported cancer-fighting effects of two old drugs: the anti-viral agent, ribavirin, produced remissions in leukaemia in humans, while the blood pressure pill, losartan, shrunk human tumours transplanted into mice.
The science behind each discovery was exciting because, in addition to their intended action, both medications appear to target specific cancer genes that may be overactive in growing tumours. Moreover, since the drugs in question are already approved, available commercially, relatively cheap, and established as safe in humans, couldn’t they be rapidly tested and marketed by drug companies to treat cancer?
The sad answer is: probably not.
Why? Because ribavirin and losartan are both generic (off-patent) drugs; their original all-encompassing “composition” patents expired after the allotted 22-year time limit. If a major drug company did take out additional patents to claim a new use (cancer treatment), it would still have to spend tens or hundreds of millions of dollars to complete the required phase 3 clinical cancer trials.
Then, if the results were positive, leading to regulatory approval, any generic drug company could manufacture the same drug and market it for its original indication (high blood pressure, for example) knowing that cancer patients, their oncologists and provincial pharmacare bureaucrats could (and likely would) substitute the cheap generic version for the major drug company’s much more costly pill. That is why, from big pharma’s perspective, such a venture, no matter how morally desirable, is usually a non-starter. After all, shareholders demand a profitable operation.
The only way around the problem would be for company chemists to tweak the old drug molecule sufficiently to obtain a new composition patent. However, changing a single atom in an old drug results in an entirely new entity from the regulatory point of view. Forget the fast-track approach. It’s back to square one and years of testing for both safety and efficacy.
Yet, corporate risk is not limited to converting old drugs to new uses. Even new, approved drugs, such as GlaxoSmithKline’s lapatanib (Tykerb), can suffer unexpected setbacks in the marketplace.
This oral medication enters cells to target both the HER-2 and Epidermal Growth Factor (EGF) pathways involved in the rapid development and spread of about 20% of aggressive (HER-2-positive) breast cancers. It was developed to treat tumours that progress on chemotherapy containing the older, intravenous drug, trastuzumab (Herceptin) that targets only HER-2.
Clinical trials showed in such cases that when Tykerb was combined with an oral chemotherapy drug called capecitabine (Xeloda), advanced HER-2-positive breast cancer progressed more slowly than in women who received capecitabine alone.
Commenting on these results in the drug company’s news release, Dr. Kathleen Pritchard, of Toronto’s Sunnybrook Cancer Centre, stated, “Tykerb is a new way to treat HER2-positive breast cancer that gives women with advanced HER2-positive breast cancer another weapon in the fight to control their disease, where before they had no other options.”
“No other options”?
Unfortunately, Tykerb’s Canadian launch coincided with a report in the Journal of Clinical Oncology showing that, even after other Herceptin-containing chemotherapy had stopped working, Herceptin plus capecitabine was superior to capecitabine alone in slowing the progression of advanced HER-2-positive breast cancer. So much for the Tykerb advantage.
But Tykerb faces an even greater problem.
Like all oral medications, Tykerb, which costs approximately $35,000 annually, will have to be billed directly to patients who may, or may not, receive a rebate from private or public insurers. On the other hand, Herceptin, like most intravenous cancer therapies, is fully covered by each province and administered “free” to patients.
Why, then, should patients or insurers pay big bucks for Tykerb when Herceptin is equally effective under the same circumstances and is already covered under provincial health plans? Unless the dollar costs change significantly in favour of Tykerb, or new clinical trials indicate situations where Tykerb is superior, this new drug may be dead in the water, at least in Canada.
The final word: Beyond the hope and hype lies the hard reality that, for a variety of reasons, virtually no old drugs, and few new ones, successfully complete the arduous journey from discovery to the cancer clinic.