A unique new cancer treatment uses gene therapy to induce a cancer-fighting immune response whose intensity can then be controlled with a pill. The combination could help tailor treatment to a patient’s individual response, MIT Technology Review reports.

The treatment uses the body’s own cells or tumor cells to produce extra copies of a naturally occurring hormone-like molecule called IL-12, which regulates anticancer immune responses. Last week, Ziopharm Oncology announced a clinical study of the treatment for patients with breast cancer. The company is already testing it in patients with melanoma.

To avoid the dangerous side of the molecule, Ziopharm’s system is designed to control IL-12 with a combined genetic and pharmaceutical switch. To activate the gene, a patient has to take a pill that delivers another molecule. The advantage is that any patient who starts to experience nasty side effects from the IL-12 can stop taking the pill.

Eventually, the system could be used to deliver multiple genetic treatments at once.