Drug developer Human Genome Sciences (HGSI) got some mixed news regarding its experimental lupus drug Benlysta, also referred to as Belimumab. The therapy met primary endpoint goals, but secondary results from the company's Phase III study revealed that the success rate diminished over time. Indeed, the latest batch of results showed that patient response rates dropped from 43.2% after 52 weeks of treatment to 38.5% at the conclusion of 76 weeks. Last November, Benlysta met its primary goal in a pair of late-stage trials at week 52.

Trial failures are not uncommon, given the arduous process each drug must undergo before applications for FDA approval are considered. Indeed, Benlysta is not the first to suffer a setback in 2010. Merck’s (MRK) experimental HIV treatment vicriviroc was one of the notable disappointments at the start of the year. The drug, which Merck acquired in its acquisition of Schering-Plough, appeared to be on track for approval this year. However, in a pair of Phase III trials, vicriviroc proved highly ineffective in 800 patients that had previous treatments with other HIV medications. Following the disappointing results, Merck decided against filing for treatment-experienced approval.

Pfizer (PFE) also had its share of letdowns in the first quarter, including the failure of a breast cancer medication and the Alzheimer drug it was developing with Medivation. Two Phase III studies showed that Sutent in advanced breast cancer did not meet its primary endpoints. And after promising early-stage results, Alzheimer drug Dimebon showed little improvement over the placebo in a study of nearly 600 patients.

Xenoport (XNPT), meantime, was denied FDA approval after its restless leg syndrome treatment Horizant showed pancreatic cell tumors in a recent study.

Even for Human Genome, this is not unchartered territory. Novartis (NVS) and Human were developing a hepatitis C drug Joulferon. However, Novartis recently withdrew its marketing application for sale in Europe.

Not all trial failures, though, completely terminate the pharmaceutical’s chance to reach the market. In fact, Human Genome and its partner in this collaboration, GlaxoSmithKline (GSK), believe that there is enough data from two earlier positive late-stage trials to support the candidate's commercialization, and the duo plan to submit regulatory applications for the U.S. and Europe sometime in the second quarter of this year. Should it make it to the market on a timely schedule, Benlysta would be the first new drug targeting lupus in over 50 years.