Key Characteristics Emerging for CAR T Cell Success Published July 18, 2018

Key Characteristics Emerging for CAR T Cell Success

Tony Hagen

David Maloney, MD, PhD
David Maloney, MD, PhD

An effective lymphodepletion (LD) strategy is critical to success with chimeric antigen receptor (CAR) T-cell therapy, but also the choice of patients and even the cells used for CAR T cell manufacturing should be made with care, said David G. Maloney, MD, PhD, at the 2018 Pan Pacific Lymphoma Conference.

Maloney, who delivered the first annual Oliver Press Memorial Lecture, gave a wide-ranging overview of key considerations for CAR T cell success, which included clinical and financial challenges ranging from distinct adverse event (AE) management to unresolved payment policies that make it risky for cancer centers to undertake treatment with these agents.

Maloney is a professor at the University of Washington and medical director of the Bezos Family Immunotherapy Clinic at the Fred Hutchinson Cancer Research Center in Seattle.

Optimizing Response
There are strong distinctions in CD4 and CD8 cell populations between patients with non-Hodgkin lymphoma and healthy donors. The role of these cells makes it important to obtain CD4 and CD8 cells and combine them in the right ratio to achieve an effective response to manufactured CAR T-cell therapy, Maloney said.1

“If you just collect the T cells and make a CAR, and don’t separate the populations, you end up with a wide range of CD4 and CD8,” he said. At Fred Hutchinson, investigators have sought to give the processed cells back to patients in a defined 1:1 ratio, which Maloney said has enabled them to improve the dose response and toxicity relationship.

In addition to cell populations, the impact of LD is critical. In an early stage study, investigators used cyclophosphamide (Cy)-based LD chemotherapy with or without fludarabine (Flu) prior to CD19-directed CAR T cell immunotherapy. The more intense the LD, which enhances the grafting of infused T cells, the higher the homeostatic cytokine levels of interleukin (IL)-7 and IL-15, which lengthens T-cell persistence. “If you do Cy/Flu, you can show a difference in the proliferation of the T cells,” and in fact it can be possible to administer a second treatment, Maloney said.

In a study of CAR T-cell therapy in patients with relapsed/refractory non-Hodgkin’s lymphoma (n = 79) by Gauthier et al presented at the 2018 ASCO Annual Meeting,2 investigators used Cy/Flu and achieved a 38% complete remission (CR) rate among patients with aggressive disease (n = 9) and an 89% CR rate among those with indolent disease (n = 48).

The same study found that CR was associated with superior progression-free survival (PFS): 57.2% of patients who achieved a CR were progression-free at the 2-year mark (95% CI, 39%-83%), whereas those with partial response (PR), stable disease, or progressive disease saw a median PFS of under 9 months. The gap extended to OS. For those achieving a CR, 78% were alive at 24 months (95% CI, 63%-97%). “If you don’t have a CR, then the outcome is quite poor,” Maloney said.

Some characteristics help predict who’s going to respond. A surprising finding by Gauthier et al was that pretreatment lactate dehydrogenase (LDH) levels in patients showed an inverse relationship to outcome. “The lower the pretreatment of LDH is, the better the response and the more likely you’re going to have a durable CR,” Maloney said.

Additionally, the more T cells proliferate, the better the response, and IL-7 and IL-18 levels also correlated with CR rates, Maloney said.

“If you put this together, you can find patients with a nearly 100% chance of long-term remission if they fit into this small subset of patients.”

Adverse Event Prevention

When it comes to cytokine release syndrome (CRS), it is important to pay attention to signs of coagulopathy. Patients can have marked transfusion requirements, and this condition can translate into hepatic and renal dysfunction, along with heart arrhythmias. At Fred Hutchinson, physicians monitor IL levels to judge whether patients are undergoing CRS, so that it can be treated successfully with tocilizumab and dexamethasone, Maloney said.

Neurotoxicity is also problematic, and at Fred Hutchinson this is treated with steroids only, unless there’s ongoing CRS, he said. The onset of CRS and neurotoxicity is very rapid following infusion, although CRS precedes neurotoxicity by several days in most cases. As CAR T cells proliferate, there’s a higher chance of having neurologic toxicity or CRS.

“There’s a direct relationship. The higher the CAR T cell proliferation, generally the higher your chances of CR. This is a balancing act—you need to be able to control the CAR T cells,” Maloney said.

He compared 2 recently approved CAR T therapies—axicabtagene ciloleucel (axi-cel, Yescarta) and tisagenlecleucel (Kymriah)—with one in development, lisocabtagene maraleucel (liso-cel; JCAR017).

Axi-cell, for diffuse large B-cell lymphoma (DLBCL), in ZUMA-1 achieved an ORR of 82% and a CR of 49% among 77 patients. “These were highly refractory patients—refractory to second or later-line therapy, and also included patients who relapsed within 12 months of autologous transplant. And the results were quite spectacular,” he said.

In a group of adult patients with relapsed/refractory DLBCL, tisagenlecleucel achieved a CR plus PR of 53% (n = 81) in the JULIET trial, with a durable ORR of 38% at 3 months and 37% at 6 months. What was a key difference for tisagenlecleucel was that it could be administered in both inpatient and outpatient settings, noted Maloney.

With liso-cel, which is not approved, cells are preselected for CD4 and CD8 and 2 populations of CAR T cells are manufactured and administered, Maloney said. The cells are tagged by a transduction marker and can be potentially eliminated by an anti-EGFR antibody if necessary. The rate of AEs has appeared milder than with the previously mentioned CAR T-cell products, Maloney said. The best CR achieved by liso-cel in DLBCL so far was 59% (n = 73).

Financial Obstacles Remain

Payment challenges abound, Maloney said. Often it is necessary to negotiate with payers on a case-by-case basis. Private payers lack clear policies. “The way it’s set up is the center pays all the money up front, and if you get reimbursed 10%, that’s your problem not the manufacturer’s.” The Centers for Medicare & Medicaid Services may bundle payments resulting in additional potential loss.

Additionally, these agents have distinct characteristics that make it impossible to generalize treatment usage and AE management. “I think we need to somehow get ourselves on the same page across all of these different drugs,” he concluded.


  1. Turtle CJ, Hanafi LA, Berger C, et al. Immunotherapy of non-Hodgkin’s lymphoma with a defined ratio of CD8+ and CD4+ CD19-specific chimeric antigen receptor–modified T cells. Sci Transl Med.  2016;8(355):355ra116. doi: 10.1126/scitranslmed.aaf862
  2. Gauthier J, Hirayama AV, Hay K, et al. Factors associated with duration of response after CD19-specific CAR-T cell therapy for refractory/relapsed B-cell non-Hodgkin lymphoma. J Clin Oncol. 2018;36(suppl; abstr 7567). record/162353/abstract.

FL CAR-T Clinical Trial Results

Chimeric Antigen Receptor Therapy (CART)

Data regarding CAR therapy in patients with FL is sparse. Especially, early disease and low-grade FL have not been addressed by clinical trials yet. The CAR T cell products relevant to FL treatment are CD19 re-targeted T-cells. These products include axicabtagene ciloleucel/Yescarta® and Tisagenleleucel/Kymriah® that are FDA approved. The best available information for CAR therapy in FL we have at this moment is from patients participating in the Juliet trial. At ASH 2015, Schuster presented the outcome of 14 FL patients with an ORR of 73% at 3 months with 4 CRs, 4 PRs, and 3 progressive disease. Three of the four PR patients converted into CRs by 6 months and the last patient with PR remained in PR for a year before progression of the disease (31). In an updated analysis encompassing 24 patients, an ORR of 53% was published. At a median follow-up of 28.6 months, sustained remissions were observed and 89% of patients with FL who had an initial response (95% CI, 43–98) could maintain the response (20).

The most notable side effects of CART therapies are cytokine release syndromes found across trials in 50–60%, up to 10% severe (grade 4) and neurological toxicities that appear in frequencies from 25 to 30% and are severe (≥grade 4) in approximately 5%. Neurotoxicity seemed to be associated with the CAR construct itself, as JCAR015 showed higher toxicities than other constructs. In a post hoc analysis of the Rocket 1, trial factors associated with higher neurotoxicity were the conditioning chemotherapy (Flu/CY or not) with a higher risk odds ratio of 7.23, the bridging chemotherapy (OR 4,68), age below 30 (OR 5.16), and less or equal 2 previous line of therapies (OR 7.24) (21). No association with higher risk was found regarding prior CNS irradiation, prior IT chemotherapy, prior CNS disease, prior allogeneic transplantation, higher ECOG performance status, or prior use of blinatumumab (21).

With the approval of two CART products in relapsed/refractory aggressive B-cell lymphomas and some 13 trials ongoing (Table 2), the value of the CART approach in FL should become clearer in the next couple of years. If long-lasting remissions can be achieved, this approach has the potential to displace autologous and allogenic stem cell transplantation in FL.


Global CAR T Therapy Trial Shows High Rates of Durable Remission for Non-Hodgkin’s Lymphoma

The New England Journal of Medicine published these data today [December 11, 2017]. Among 28 patients who received the therapy in the single-site pilot trial after their cancers had come back following standard treatments, 43 percent of DLBCL patients achieved complete remission, as did 71 percent of patients with follicular lymphoma, the second most common form of the disease. All patients who were in remission at six months are still in remission, after a median follow-up of 28.6 months.


CAR T cell therapy shows long-lasting remissions in non-Hodgkin’s lymphoma patients

The New England Journal of Medicine published these data today. Among 28 patients who received the therapy in the single-site pilot trial after their cancers had come back following standard treatments, 43 percent of DLBCL patients achieved complete remission, as did 71 percent of patients with follicular lymphoma, the second most common form of the disease. All patients who were in remission at six months are still in remission, after a median follow-up of 28.6 months.

“Taken together, our data from both trials show that most patients who are in remission at three months stay in remission,” said Schuster, who is the Robert and Margarita Louis-Dreyfus Professor in Chronic Lymphocytic Leukemia and Lymphoma Clinical Care and Research in the Perelman School of Medicine and director of the Lymphoma Program at the Abramson Cancer Center.