Why would a Salmonella bacterium be used against cancer?

Salspera, Inc. proposes that attenuated Salmonella tends to grow in the low-oxygen environment inside many solid tumors, where the bacteria could deliver immune-stimulating IL-2. The proposal rests on animal studies from the originating University of Minnesota laboratory, and tumor colonization by Saltikva has not been confirmed in patients. Bacterial approaches to cancer have been studied for over a century, and Saltikva remains investigational.