A baby's "incurable" leukemia was reversed after being administered with what appears to be a wonder drug: Cellectis "designer" immune cells. She was the first human ever to receive the treatment, but experts said a total cure is still uncertain. Nonetheless, the progress she has shown so far is a significant milestone in the said medical field.

Layla Richards was only 3 months old when she was diagnosed with acute lymphoblastic leukemia (ALL). She underwent various treatments including bone marrow transplant and chemotherapy, but like other very young children, she was not cured.

Doctors at Britain's Great Ormond Street Hospital (GOSH) then offered an experimental drug that contains genetically-modified cells, which may be administered via intravenous injection. The family agreed and two months, later, Layla was cancer-free. Layla has been discharged from the hospital and is now staying at home.

As Layla's cancer was aggressive, Paul Veys, the leader of Layla's medical team and the director of bone marrow transplant at GOSH said that the positive response can be considered a miracle.

The prognosis of Layla now raises questions as to how this immune cell therapy differ from existing treatments for ALL and in what way is it more effective.

ALL in children is a kind of cancer that is characterized by the production of immature white blood cells by the bone marrow.

At present, the four standard types of ALL treatment include chemotherapy, radiation therapy, chemotherapy with stem cell transplant and targeted therapy. These modalities aim to kill the leukemia cells that have been transported to different body sites such as the brain and spinal cord.

Chemotherapeutic drugs work by halting the spread of leukemia cells through killing or preventing its division. Administering the drugs via intravenous route would allow it to spread throughout the body system and kill the cells. If chemotherapy medicines are introduced to a particular body part, like the abdomen or in the spinal cord, it likely targets cancer cells within the said area.

Radiation therapy utilizes powerful x-rays and other forms of radiation to kill or prevent cancer cells from growing. This treatment option has two types: external and internal. External radiation therapy uses a device outside of the body to deliver radiation while the internal type involves needles and catheters to place radioactive agents directly or near the cancer.

Chemotherapy with stem cell transplant is performed by administering high doses of chemotherapeutic drugs to the patient, which results in the destruction of blood-forming cells. Another person, not necessarily related to the patient, would then need to donate healthy stem cells, which would be infused into the patient. The new stem cells would then be restored and grow into new blood-forming cells.

Targeted therapy includes a treatment option that has a specific focus of action. These drugs determine and attack particular cancer cells without affecting normal cells.

Aside from standard treatment, patients may also opt to undergo clinical trials that aim to discover a potent treatment for cancer.

The treatment used on Layla was still in the clinical trial phase and was derived from a highly-advanced process of gene editing, prepared by experts from GOSH, University College London (UCL) and French biotech company Cellectis. The therapy works by injecting new genes to healthy donated T-cells, which shields it against leukemia.

At present, Cellectis is going to fund the full clinical trials of the treatment, which would be due in 2016.

"This is a landmark in the use of new gene engineering technology and the effects for this child have been staggering," said medical team member Waseem Qasim, a professor of Cell and Gene Therapy at UCL and an immunologist at GOSH. He added that if the good outcomes of Layla's case is followed through and carried on to other patients, the treatment could signify a huge step in the treatment of leukemia and other cancers.

The findings and details of Layla's case would be discussed at the American Society of Hematology's annual meeting in Orlando.