Recently launched and relatively small Avista Therapeutics Inc. has just cut a deal with comparatively massive Roche Holding AG that could bring the new Pittsburgh-based company more than $1 billion.  Avista’s single cell adeno-associated virus (AAV) platform will be used to develop intravitreal AAV capsids that match a Roche-defined capsid profile. Roche will evaluate and license Avista’s capsids and conduct the preclinical, clinical and commercialization work for the gene therapy programs.