By John Carroll | Fierce Biotech

What if you had a great combination of rival drugs that worked in 100% of patients, but one of the companies involved refused to participate in the trials needed for an approval? If you’re Gilead, the answer is to continue to ignore compelling data, shun the competitor drug and stay focused on an in-house combo that could deliver a big segment of the market. But some patients and doctors appear willing to consider taking matters into their own hands.

Over the weekend investigators went over the numbers for sofosbuvir and daclatasvir, which demonstrated that after 12 weeks the combo cleared 100% of the virus among 40 patients who had already failed the two leading therapies, Incivek and Victrelis. That’s the toughest group of patients to target. And there was solid proof that the combination worked among patients in the genotype 3 group, a sizeable minority of the market in key regions of the world.

Gilead’s sofosbuvir is the $11 billion jewel the biotech acquired with the Pharmasset buyout. But after finding that it worked to perfection in combination with competitor Bristol-Myers’ great hep C hope, daclatsvir, Gilead determined its best market opportunity lay with its own in-house combination with ledipasvir (GS-5885). Investigators like Graham Cooke at Imperial College say that sofosbuvir/ledipasvir looks like a clear winner in the large genotype 1 population, but G3 patients may be missing out on sofosbuvir/daclatasvir.

“We probably have a better option for G3 that we could be using if the companies were cooperating,” Cooke told Bloomberg. “Daclatasvir and sofosbuvir looks much better but Gilead very clearly wants to develop in-house.”

Both daclatasvir, now combined in a number of clinical studies with outside drugs, and sofosbuvir appear headed for approvals. That opens the door to an off-label combo. Provided patients could afford it, payers would cover it and doctors can be satisfied that it’s safe without a pivotal Phase III study.

“Lots of investigators around Europe and the U.S. are itching for the opportunity to put together what they believe to be the optimum combination for our patients,” Mark Thursz, the secretary-general of the European Liver Society, told Bloomberg. “The only barrier to that is what is the combination cost going to be because I suspect there will be package deals to be had.”