Eli Lilly reported promising results from a study of its experimental oral drug that could rival popular injections to treat obesity and diabetes.

But this one, for Lilly’s first diabetes and weight-loss pill based on the GLP-1 hormone, was particularly fraught. Days before, rival pharma giant Pfizer had announced it was abandoning its oral weight-loss drug after worrying side effects involving liver problems were reported in one participant in the trial.