The proMel‐mediated gene therapy might be also superior to a recently developed suicide gene therapy using secretory TRAIL.21 TRAIL therapy, whose efficacy depends on the expression of death receptors DR4 and DR5 on target cells, has a major limitation in that some tumors lack expression of those receptors, and many tumors develop resistance toward TRAIL over time.22 In contrast, melittin kills cancer cells through cytolytic effects without selectivity. The gene discussed is TNFSF10; the disease is cancer.