An international consortium engineered a bacterial strain that overcomes decades‑old biosynthetic constraints in the production of doxorubicin, a cornerstone anthracycline chemotherapy. The work—published in Nature Communications—identifies and resolves metabolic and enzymatic bottlenecks that had prevented scalable biosynthesis from natural producers for more than 50 years. By enhancing pathway flux and expression of previously cryptic genes, the team demonstrated higher yields and a path to bio‑manufacture that could reduce reliance on complex chemical synthesis. The advance has implications for cheaper, greener manufacturing of cytotoxic drugs and could catalyze investment in microbial production platforms for other complex natural products.