An experimental treatment has saved the lives of two infants with difficult to treat leukemia.

The two children, 11 and 16 months old, each experienced complete cancer remission within 28 days of receiving treatment.

Diagnosed with B-cell acute lymphoblastic leukemia (ALL), both infants had exhausted all other treatment options.

ALL is an aggressive type of cancer that begins in immature white blood cells called lymphocytes. Without treatment, ALL can be fatal within months.

According to the American Cancer Society, children with B-cell ALL who are between the ages of 1 and 9 have better cure rates. Infants under 1 year old tend to have a poorer outlook.

The two infants given the experimental treatment have both been cancer-free for more than a year.

The research was published in Science Translational Medicine.

Read more: Fewer children dying of cancer though more kids have the disease »

How T cell treatment works

When other methods such as chemotherapy don’t work, there’s a newer leukemia treatment that involves using a patient’s own T cells.

The T cells are removed and manipulated with chimeric antigen receptors (CARs) that instruct them to attack ALL cells. Then they’re returned to the patient’s blood.

However, most infants during their first year haven’t developed enough healthy T cells.

Dr. Waseem Qasim, professor of cell and gene therapy at Great Ormond Street Institute of Child Health, University College in London, and his colleagues, wanted to find a solution to this problem.

Unable to get enough T cells from the infants, they decided to use donor blood.

Through gene editing, they created functional T cells that could evade immune system attacks in unmatched recipients.

The T cells were then infused into the infants’ blood.

Two months after the procedure, one infant developed mild graft-versus-host disease in the skin. It cleared up following a bone marrow transplant and steroid treatment. The other infant had no complications.

It’s the first time doctors have ever treated cancer with altered T cells from a donor.

The doctors showed it’s possible to create universal, or “off-the-shelf,” therapies from altered donor T cells.

The experiment could lead to big advances in hard to treat ALL.

Read more: Despite setback, CAR-T treatment moves forward »

The promise of off-the-shelf T cells

With no need to match patients with donors, patients could be treated more quickly and more efficiently.

“Engineered T cells are the most important story in difficult to treat leukemias and lymphomas,” said medical oncologist Dr. Jack Jacoub in an interview with Healthline.

“A lot of progress has been made in this type of treatment. It’s an area that has excellent promise and definitely needs to be considered,” said Jacoub, the director of thoracic oncology at MemorialCare Cancer Institute at Orange Coast Memorial Medical Center in California.

“This type of lymphoblastic leukemia is a very bad disease,” he added. “There’s often little to be lost. This is the case with these two infants. They were provided therapy on a compassionate basis. All other therapies failed, so there was nothing to lose. They would have succumbed to this illness.”

“The paper’s authors suggest there are limitations in getting lymphocytes in young patients. They have a less mature immune system. They don’t have enough T cells, and that’s a problem,” said Jacoub.

“The authors are implying we don’t need to go to the patient or have a donor. We don’t need either route,” he explained.

Read more: Progress reported in new treatments for people with lymphoma »

Next steps for researchers

“In these two infants, they’ve showed they can do it,” said Jacoub. “It’s only two [patients] and they tried it because there was nothing else. But it’s not even a phase I trial structure.”

Jacoub notes that the paper was published in a small journal that may not be widely received throughout the field of hematology. He’s fairly certain, however, that this paper is on the radar of scientists involved in the field.

Also worthy of note is the small sample size.

“We don’t know how the next patients will do. This is just an observation, but an exciting one that must be expanded,” he said.

Jacoub suggests the need for more collaboration with larger institutions with research infrastructure, more of these types of patients, and the expertise to manage this disease.

“Whether it will go to phase I trial is a big leap. It will have to involve more than one institution. Right now, it’s just an observation of two patients. We won’t be rushing out to try to do this now, but this is how things start,” he said.

Jacoub sees a lot of potential in this type of treatment. But there’s a long way to go.

“The U.K. trial would have to be reproducible in the United States to see if this is feasible. With more scientific scrutiny and oversight — if we can reproduce it — it could be enormous. Barriers would be overcome,” he said. “They’re taking available technology a few extra steps. The technology is there. If it really was a true effect and can be reproduced in different settings and countries, it could lead to widely available therapeutic options. If this observation could be accurately reproduced, we’ll probably know in the next year or two. That’s how fast this field moves.”

Jacoub said this is exciting news for patients and their families.

“It’s not widely available or the current standard of care. But families of these patients are usually medically savvy,” he said.

He’s all for families bringing it up with their physicians.

“It’s OK if their doctor hasn’t seen this published report. Copies of this journal may not go everywhere. Usually these things happen in collaboration. Emails to scientists and institutions start discussions. So they should definitely bring it up.”