EDITOR’S NOTE: The author, Greg Tufaro, lost a child to post-transplant lymphoproliferative disorder (PTLD). He has no financial interest in Atara Biotherapeutics. His personal story is to inform readers of a potential treatment for solid organ and bone marrow transplant recipients battling PTLD, a rare form of blood cancer with which his late daughter was diagnosed two years ago today.

A San Francisco-based biotechnology company is in late-stage development of an immunotherapy that may have been able to prevent my beautiful 13-year-old daughter’s death.

Atara Biotherapeutics’ tab-cel is a potential treatment for solid organ and bone marrow transplant recipients with Epstein-Barr virus-associated post-transplant lymphoproliferative disorder (PTLD), the rare form of blood cancer that claimed Marisa’s life less than seven months after she received a heart transplant.

I signed a consent form allowing Marisa to be part of a clinical study to receive the potentially life-saving “immunity in a vial” in January of last year, two days after Marisa was placed on a ventilator and three weeks before she passed.

Marisa was eligible for the study because the treatment protocol for patients with PTLD – including a prescription medication called Rituxan and, in my daughter’s case, chemotherapy – failed to thwart the relentless onslaught of the disease that riddled her brain and body.

She died on the same day the screening period to receive tab-cel ended, and after repeated last-ditch attempts at whole-brain radiation therapy failed.

The incidence of PTLD in adults following heart transplant ranges from 2 to 8 percent, according to the Leukemia and Lymphoma Society’s most recent fact sheet, published three months ago with Atara’s support.

Marisa’s case of PTLD, according to the medical director of heart failure, cardiomyopathy and cardiac transplantation at one of the nation’s leading children’s hospitals, was “a very grave form” that “occurred very early (three months) after transplant and was very widespread.”

“I would qualify that as a rare occurrence,” the doctor said of Marisa’s PTLD. “Quite honestly, it’s rare enough that in my own limited practice (with PTLD) I would say I haven’t seen proliferation into the brain. I can imagine that it would be very much so a more difficult scenario to treat.”

Despite the apparent insurmountable odds, I’d like to believe that had Marisa been able to receive and respond to Atara’s special immune cells before the PTLD spread to her brain, she would have had a better chance of survival.

My logic should in no way be construed as a criticism of Marisa’s medical team, but solely interpreted as the wishful thinking of a grieving father who has scrutinized the data from the tab-cel Phase II studies.

Patients with PTLD who Rituxan failed have an expected survival rate of 15 to 56 days, according to Atara.

Patients with PTLD who failed Rituxan but responded to tab-cel in Atara’s Phase II studies, after around two years of follow up, have not died of PTLD, nor have they lost an organ. During that span, 50 percent of solid organ transplant recipients with PTLD and 69 percent of bone marrow transplant recipients with PTLD who were part of Atara’s Phase II studies responded to tab-cel. The immunotherapy was generally well-tolerated.

Born with a complex cardiac defect, known as hypoplastic left-heart syndrome, which required six open-heart surgeries, Marisa developed two life-threatening conditions – protein-losing enteropathy and plastic bronchitis – that necessitated a heart transplant.

Despite being hospitalized for more than two years and maintaining hundreds of doctors’ appointments, Marisa lived a vibrant life that inspired. She was an honor roll student in elementary and middle school and involved in several extracurricular activities.

I’m grateful for the 13 years God blessed us with Marisa, but struggle to live with the cruel irony that the transplant performed to save her life inevitably claimed it, along with the heart of a donor whose family is also grieving.

Transplant recipients must take immunosuppressant medications to ensure their new organs won’t be rejected. The drugs protect the organ but make patients, such as Marisa, vulnerable to the Epstein-Barr virus (EBV), which most commonly causes mononucleosis but is also responsible for PTLD. For most people, EBV never poses a health risk. However, when a patient’s immune system is compromised, as is the case for transplant patients, EBV can cause cancer such as PTLD lymphoma in which blood cells grow abnormally.

The allure of tab-cel is that it can be taken along with anti-rejection medications, giving solid organ and bone marrow transplant recipients the ability to fight against EBV-driven cancer without threatening the transplanted organ. Tab-cel is designed to identify and kill the EBV-positive lymphoma cells without harming normal tissues.

Atara’s special immune cells, called EBV-specific T cells, are manufactured using cells from a healthy person who is immune to EBV. In order to work, the EBV-specific T cells are matched to the patient’s immune profile and the treatment is selected from a pre-manufactured bank containing an array of frozen EBV-specific T cell lines.

“Tab-cel is innovative in the sense that these T cells have been manufactured in advance and are stored in Atara’s inventory,” Atara Biotherapeutics Vice President of Investor Relations and Corporate Communications John Craighead said. “When a patient is in need, we match the patient to the right cells and expect to deliver tab-cel within three to five days to the patient. Atara’s immunity in a vial is for these very unique cases of patients who desperately need their immune systems to work to protect against EBV-associated lymphomas and cancers caused by that virus.”

The cells, which are shipped frozen and can generally be administered to patients in under a half hour, are infused in cycles with several hours of close monitoring.

Dr. Susan Prockop, with whom I had the privilege of speaking at length last year regarding Marisa’s case in the days before she died, and Dr. Richard O’Reilly, both of Memorial Sloan-Kettering (MSK) Cancer Center in New York City, “have been the pioneers in bringing tab-cel to the point where Atara licensed the program from MSK,” Craighead said, noting the two oncologists in approximately a decade “brought this a long way in clinical development.”

Earlier this year, Atara commenced tab-cel Phase III studies – the final step before seeking FDA approval – for patients with PTLD at medical centers across the United States with the goal of expanding to sites in Europe, Canada and Australia.

The company has received a special status from the FDA called breakthrough therapy designation, which Craighead said is granted for “products for serious conditions where there are high unmet needs and early clinical evidence shows the product may have a substantial improvement over other options available to patients.”

Craighead said the designation “opens up a regulatory mechanism with the FDA to accelerate the development and potential approval” of tab-cel. Atara hopes to have data from its Phase III study within the next nine months.

Until then, I’ll keep the statement of consent I signed last year for Marisa to partake in Atara’s tab-cel clinical study in my nightstand drawer, serving as a constant reminder of what may have been.

I’m hoping Atara Biotherapeutics, with help from a certain angel working from above, will have an opportunity to save many lives.