Some patients with blood cancers for whom all other therapeutic options have been exhausted have one final chance of getting rid of their disease: treatment with chimeric antigen-receptor (CAR) T cells.
Described as a “living drug,” the treatment involves genetically engineering the patient’s own blood cells and reinfusing them back into their system. These CAR T cells then hunt down and destroy cancer cells; in some cases, they manage to eradicate the disease completely.
About half of patients with leukemia or lymphoma and about a third of those with multiple myeloma who receive this treatment have a complete remission and achieve a functional “cure.”
But not all patients who could benefit from this therapy are able to get it. Some are spending months on waiting lists, often deteriorating while they wait. These patients have exhausted all other therapeutic options, and many are facing hospice and death.
The scope of this problem was illustrated by a recent survey of the centers that are certified to deliver this complex therapy.
The survey was led by Yi Lin, MD, PhD, associate professor of medicine at the Mayo Clinic, Rochester, Minn., and medical director for the cellular therapy program. It was published as an abstract at the annual meeting of the American Society of Clinical Oncology recently, although it was not presented there.
“We wanted to find out just how widespread this problem is,” Dr. Lin said, adding: “There had been nothing in the literature thus far about it.”
The team contacted 20 centers across the United States and received responses from 17. Results showed that the median time on the waiting list was 6 months and that only 25% of patients eventually received CAR T-cell therapy. An additional 25% were able to enter a CAR T clinical trial. The remaining 50% of patients either were enrolled in a different type of trial, entered hospice, or died.
For patient selection, all centers reported using a committee of experienced physicians to ensure consistency. They employed different ethical principles for selection. Some centers sought to maximize the total benefit, such as selecting the patients most likely to achieve leukapheresis or a clinical response, while others based their decisions on the time patients spent on waiting list or gave priority to the patients who were the “worst off” with the most limited therapeutic options.
Shortage affecting mostly myeloma patients
The shortages in CAR T-cell therapies primarily involve the products used for patients with multiple myeloma.
The problem has not, as yet, noticeably spilled over to lymphoma and leukemia treatments, which use a slightly different type of CAR T-cell therapy (it targets CD19, whereas the cell therapies used for myeloma target BCMA).
“We have backlog of myeloma patients who don’t have access,” said Nina Shah, MD, a hematologist and professor of medicine at the University of California, San Francisco. “We have only four slots for the two myeloma products but about 50-60 eligible patients.”
Long waiting times for CAR T cells for myeloma have been an issue ever since the first of these products appeared on the market: idecabtagene vicleucel (ide-cel; Abecma), developed by Bluebird Bio and Bristol-Myers Squibb. “As soon as it became available in March 2021, we had people waiting and limits on our access to it,” Dr. Shah said.
A second CAR T-cell therapy for myeloma, ciltacabtagene autoleucel (cilta-cel, Carvykti), developed by Janssen and Legend Biotech, received approval in February 2022. While that helped provide centers with a few more slots, it wasn’t sufficient to cut waiting times, and the demand for these myeloma therapies continues to outstrip the capacity to produce CAR-T products in a timely manner.
“For myeloma, the demand is very high, as most patients are not cured from any other existing myeloma therapies, and most patients will make it to fifth-line therapy where the two CAR T-cell products are approved right now,” said Krina K. Patel, MD, medical director of the department of lymphoma/myeloma in the division of cancer medicine at the University of Texas MD Anderson Cancer Center, Houston.
“We likely have 10 eligible CAR-T myeloma patients each month at our center,” she said, “but were getting two slots per month for the past 8 months, and now are getting four slots a month.”
“Our clinic has also experienced the impact of the low number of manufacturing slots offered to each cancer center for some CAR T-cell products,” said David Maloney, MD, PhD, medical director, Cellular Immunotherapy and Bezos Family Immunotherapy Clinic, Seattle Cancer Care Alliance.
He noted that, as with other cancer centers, for multiple myeloma they are provided a specific number of manufacturing slots for each treatment. “Our providers discuss which patients are most appropriate for available slots for that month,” said Dr. Maloney.
“Additionally, juggling patient schedules may be required to address the extended manufacturing time for some products. In some cases, clinical trials may be available in a more timely fashion for appropriate patients, and in some cases, switching to an alternative product is possible,” he commented.