In September, Tidmarsh went after Tang’s Aurinia and its drug voclosporin that treats lupus nephritis, a disease in which the immune system attacks the kidneys. In a startling post on his LinkedIn account, Tidmarsh claimed that the FDA-approved drug had not been shown to provide “hard” clinical benefit and that the drugmaker had not performed necessary trials. Such a post from the FDA’s top drugmaker turned heads. Aurinia claims its share price fell 20 percent in a matter of hours, dropping $350...