Merck and Gilead square off in battle of the next-next-gen hep C combos

Early today both Gilead and Merck issued new data on their next-next-gen hepatitis C combos, demonstrating just how brutal the competition for market share is becoming while highlighting some of the boundaries that are emerging in shortening treatment regimens.

Gilead ($GILD) was first off the mark with mid-stage data for its triple hep C drug, combining Sovaldi with the experimental NS5A inhibitor GS-5816 and GS-9857, an NS3/4A protease inhibitor.

In a late-breaker at the annual meeting of the European Association for the Study of the Liver in Vienna, Gilead investigators highlighted a sustained response for the triple of 93% among treatment-naïve noncirrhotic patients after 6 weeks of therapy. That figure dropped to 87% for cirrhotic patients and 67% for treatment-resistant patients. The 4-week SVR rate simply failed with a 27% response rate, which will likely bar Gilead's combo from joining any fast-acting therapies that may eventually compete for this category.

Merck ($MRK), meanwhile, added another positive data point to its grazoprevir/elbasvir combo, which recently regained a breakthrough drug designation for two narrow patient populations and may be on track to a quick approval before the end of this year. Among what it calls a "pre-specified" group of chronic kidney disease patients, 99% were cured after 12 weeks of therapy. That may sound high, but Merck explains that it excluded 5% of the group "due to missing data caused by death or early discontinuation for reasons unrelated to study drug."

That point may come up again. Intent to treat--or ITT, evaluating the data for all the enrolled patients--remains the gold standard for data analysis in the drug development world.

Now that the first two new oral hep C drugs from Gilead and AbbVie ($ABBV) are on the market, the most intense competition in the clinic is focused on specific subpopulations and faster overall cure rates. Achillion ($ACHN) underscored that trend a couple of months ago when it released the results of a small but successful 6-week study of its NS5A inhibitor ACH-3102 and Gilead's Sovaldi and then pivoted to launch a 4-week trial.

The next step in the competition for the hep C market won't be pretty (from a producer perspective) once the next round of approvals begins. Gilead seized an early lead with Sovaldi followed by its combo Harvoni. AbbVie then weighed in, slashing prices for a less convenient combo with more complicated dosing regimens, which payers were quite willing to accept in exchange for discounts. Now Merck is set to enter the game, further roiling the market as it sets out to prove that it can grab market share as well.

Gilead CSO Norbert Bischofberger

Gilead CSO Norbert Bischofberger counted himself encouraged by the new, unremarkable 6-week data.

"These data support the ongoing development of GS-9857 and the potential for an all-oral, triple combination therapy containing Sovaldi, GS-5816 and GS-9857 to attempt to further reduce treatment duration for hepatitis C patients," he noted in a statement. "We are encouraged by the six-week SVR12 rates and other data presented at EASL demonstrating this regimen's pan-genotypic potential, and have recently initiated additional Phase 2 studies to further evaluate the appropriate treatment duration of this regimen for all patients, regardless of genotype, including those who have failed prior therapy with directly acting antivirals and those with cirrhosis."

Merck, meanwhile, stayed focused on the positive aspects of subpopulation studies.

"These data highlight how emerging innovations in chronic hepatitis C treatment may lead to new options for patient populations in which it historically has been difficult to achieve high rates of sustained viral clearance," says Dr. Eliav Barr, vice president, infectious diseases, Merck Research Laboratories.

- here's the release from Gilead
- and the release from Merck

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