UPDATE 1-AbbVie reports two patient deaths in rheumatoid arthritis study

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Sept 11 (Reuters) - AbbVie Inc said on Monday two patients died in a late-stage trial testing its rheumatoid arthritis drug, raising safety concerns about the drug.

The drugmaker said the reason for one of the deaths was unknown, while the second patient died due to heart failure and presumed pulmonary embolism, or blockage of arteries.

The trial was evaluating two doses of the drug upadacitinib - 15 mg and 30 mg - in patients with moderate to severe rheumatoid arthritis (RA), who did not adequately respond or were intolerant to other anti-rheumatic drugs.

In April, the U.S. Food and Drug Administration had declined to approve Eli Lilly and Co's rival drug, baricitinib, calling for an additional clinical study.

Three months later, Lilly said the FDA was concerned about a small, but increased number of potentially dangerous blood clots seen in baricitinib patients in clinical trials, outlining a likely multi-year delay for the drug.

AbbVie's upadacitinib, however, met all the main goals of the trial, the company said.

The drug had succeeded in the first late-stage trial in RA patients who had not adequately responded to standard treatments.

AbbVie's shares were down about 1.2 percent at $84.35 in premarket trading. (Reporting by Divya Grover in Bengaluru; Editing by Shounak Dasgupta and Saumyadeb Chakrabarty)