Esker Therapeutics has launched with $70 million in series A financing from the investment firm Foresite Capital to develop drugs for autoimmune diseases. The San Francisco–based start-up’s lead program is an inhibitor of a tyrosine kinase called TYK2. It’s in a Phase 1 clinical trial as a treatment for psoriasis. Esker says the compound is more selective for TYK2 than it is for JAK1, a similar kinase. Bristol Myers Squibb and Pfizer also have TYK2 inhibitor programs.