The drug industry’s big bet on expensive targeted cancer drugs may be starting to fail.
In recent years, companies like Pfizer have put more targeted cancer drugs into trials than ever before. (See Can Cancer Cure Pfizer?) the drugs aim at one or more defective growth promoting genes inside tumor cells.
Companies hope to duplicate the enormous success of drugs like Avastin from Roche (colon, breast, and lung cancer) and Gleevec from Novartis (leukemia). But while a few trials of targeted drugs have succeeded spectacularly, especially in less common tumors like kidney cancer, many more have failed. “Some targeted therapies are working but not nearly as much as people have expected,” says Jonathan Lewis, chief executive of Ziopharm Oncology.
Just last night, Pfizer said that its targeted kidney cancer drug Sutent had failed in two big trials in breast cancer patients–a potentially much bigger market. In a second news release, it revealed its experimental lung cancer drug figitumumab had failed its second big trial.
Meanwhile, Roche put out the news that its bestselling Avastin drug had failed in a giant trial of prostate cancer patients. this follows a big failure in early-stage colon cancer patients last year.
The poor results raise serious questions about the wisdom of drug companies betting so heavily, in follow-the-leader fashion, on targeted cancer drugs. Drug companies can still charge immensely for cancer drugs when they do work, but the odds of them coming up with a whole slate of multi-billion drugs for common tumors appears to be dimming quick.
A big problem is that despite all the advances in DNA sequencing, scientists still don’t know which of gene mutations are most crucial for driving tumor growth in specific patients’ cancers. Herceptin for breast cancer and Gleevec for leukemia–the two largest breakthroughs to date–work so well because they target very specific molecular defects that drive growth in certain subsets of tumors. But for most common cancers, doctors simply don’t know exactly which bad genes to target.
Figitumumab, the failed lung cancer drug from Pfizer, is one of several drugs in testing that aim to disable a growth-promoting protein called IGF-1 receptor. Merck, Eli Lilly and other drug companies have similar drugs in tests. But exactly which types of tumors the drugs will work in is completely opaque right now. They appeared to show signs of efficacy in lung cancer, but that so far has not been borne out in large trials. Pfizer is still testing figitumumab in other tumor types. In early afternoon trading, Pfizer shares were down about 1.5%.
The IGF-1 drugs “make all the sense in the world. Yet they are blowing up all over the place,” says Ziopharm’s Lewis. In December, Roche discontinued development of an IGF-1 drug called RG1507 that had been in testing for sarcoma and lung cancer.
Lewis says that some big drug companies are starting to consider going back to working on safer versions of toxic chemotherapy, an approach his small company is championing. His company is testing a new less-toxic version of an ancient chemo drug for sarcoma, with promising results so far.