Immunotherapy benefits relapsed stem cell transplant recipients

For many patients with advanced blood cancers, a stem-cell transplant can drive the disease into remission. However, about one-third of these patients experience a relapse and face a very poor prognosis.

But a Dana-Farber Cancer Institute study published in the New England Journal of Medicine suggests that a new treatment approach, using repeated doses of an immunotherapy drug, can restore a complete remission for some patients in this predicament. This strategy could potentially prevent such relapses in the future.

An immune checkpoint-blocking drug approved for metastatic melanoma, ipilimumab, was given to patients with relapsed hematologic malignancies in an effort to revive the tumor-fighting powers of the donors’ transplanted immune systems. A weakening of the transplanted immune response over time is believed to allow the cancers to recur.

The patients received varying doses of ipilimumab repeatedly for up to one year. Ipilimumab blocks an immune checkpoint, CTLA4 that helps cancer cells evade the immune defenses.

“We believe the donor immune cells are present but can’t recognize the tumor cells because of inhibitory signals that disguise them,” said Matthew Davids, MD MMSc, a member of the Division of Hematologic Malignancies at Dana-Farber and first author of the study. “By blocking the checkpoint, you allow the donor cells to see the cancer cells.” Ipilumumab has been used primarily in treating advanced melanoma, but in the new study, it proved effective for blood cancers in the post-transplant setting.