An experimental cell therapy that boosts the immune system continues to produce remarkable remissions as it is tested in more patients with more types of advanced blood cancer, says a University of Pennsylvania team led by gene-therapy pioneer Carl June.

The team, which includes physicians at Children's Hospital of Philadelphia, presented the latest results last week at the annual meeting of the American Society of Hematology.

The novel therapy involves engineering patients' own disease-fighting T cells to attack the blood cells that turn malignant in certain leukemias and lymphomas.

The Food and Drug Administration in July gave the immunotherapy "breakthrough" designation, intended to expedite its approval. The drug giant Novartis is partnering with Penn to commercialize the treatment, which began clinical testing about four years ago.

The therapy typically triggers an immune overreaction that causes severe flulike symptoms. While researchers have used a new arthritis drug to relieve this toxic side effect, it was fatal for three adult patients who turned out to have pneumonia or other serious infections at the same time.

Researchers summarized the latest results from more than 125 patients:

For the first time, the immunotherapy has been used to treat two types of non-Hodgkin's lymphoma. Four of five adults with follicular lymphoma had complete remissions; four of 11 adults with diffuse large B cell lymphoma remain cancer-free, the longest nearly 9 months.

Of 39 children treated for acute lymphoblastic leukemia, 36 (92 percent) had complete remissions. After a median follow-up of six months, 25 children (69 percent) stayed in remission. The first child on the therapy, Emily Whitehead, 9, of Philipsburg, Pa., has been cancer-free since April 2012. But 10 children whose cancer was eradicated relapsed, and five have died.

Chronic lymphocytic leukemia, which usually grows slowly and is the most common type of leukemia in adults, does not respond as well to the immunotherapy.