By combining synthetic biology and RNA therapy, the team at startup Strand Therapeutics Inc. hopes to make mRNA therapy more effective. Strand recently announced an immuno-oncology deal with Beigene Ltd. that netted the company $5 million to begin with and could end up being worth more than $250 million. Beyond immuno-oncology, the company’s basic technology could be broadly useful for both mRNA- and cell-based therapies.