A “mirror” molecule can starve cancer cells without harming healthy cells

Scientists have discovered that a rare “mirror-image” version of the amino acid cysteine can dramatically slow the growth of certain cancers while leaving healthy cells largely untouched. Unlike most anticancer treatments that harm normal tissues, this molecule—called D-cysteine—is taken up mainly by some cancer cells through a specific transporter on their surface. Once inside, it shuts down a crucial mitochondrial enzyme that cancer cells rely on to produce energy and maintain DNA, effectively halting their growth.