Roche expects a new generation of drugs targeted at specific groups of patients to make up half its portfolio in 10 years, a shift that is pushing the boundaries of modern medicine, according to Reuters.

In an interview, Roche chief executive Severin Schwan compared advances in molecular biology that are improving understanding of how cells work to the revolution in medicine several centuries ago when doctors first started opening up patients' bodies.

"In 10 years we would see half of our portfolio to be targeted therapies. And if anything, I would assume in 20 years this percentage is going to increase," Schwan said.

Roche leads the pack in targeted therapies thanks in part to its closely integrated diagnostics arm that helps its pharma division pinpoint the gene mutations its drugs should zero in on.

Its $6.6 billion breast cancer drug Herceptin broke new ground in the field a decade ago as a drug designed to treat only women who make too much of the HER2 protein, around 20% of sufferers.

Half of the products in Roche's late-stage pipeline already have companion diagnostics -- tests that determine if the patients are a genetic fit with the therapies.

Schwan believes the diagnostics-pharma combination will give the company an edge for years to come as the model is hard for rivals to copy."We believe that by having it integrated at a very, very early stage, we have a competitive edge," Schwan said.

Players like cross-town rival Novartis and U.S. group Pfizer, which are also active in oncology, are among those following in Roche's footsteps, said Schwan.

"Everybody is forced to follow the science," he said, adding he expects autoimmune diseases like asthma to be the next field to benefit from such a targeted approach after cancer, and perhaps even central nervous system illnesses too.

Schwan has high hopes for Roche's asthma drug Lebrikizumab, now in late-stage trials. "If this works, I believe this will change the standard of care for asthma treatment," he said.

Schwan is convinced he will be able to charge a premium for targeted therapies despite worldwide healthcare spending cuts.

Better targeted medicines will also help cut costs as those patients whose genetic makeup means they will not benefit from a drug simply will not get it, reducing spending on administering drugs as well as the cost of potential side effects, he said.

The costs of developing drugs could potentially also fall, Schwan said, as fewer patients will be required for a drug to meet its endpoint in a late-stage trial.

Schwan said that making drugs for smaller patient populations did not spell the end of blockbusters, those that rake in sales of more than $1 billion, pointing to the success of Herceptin.