‘Remarkable’: CAR T Therapy for CLL/SLL

The CD19-directed chimeric antigen receptor (CAR) T-cell therapy lisocabtagene maraleucel (liso-cel, Bristol-Myers Squibb), showed efficacy in achieving complete responses among patients with relapsed or refractory chronic lymphocytic leukemia (r/r CLL) or small lymphocytic lymphoma (SLL), after treatment with a Bruton kinase inhibitor (BTKi) and BCL2 inhibitor.

The phase 1/2 TRANSCEND CLL 004 trial represents “the first pivotal multicenter trial to evaluate a CAR T-cell therapy in heavily pretreated patients with relapsed or refractory chronic lymphocytic leukemia or small lymphocytic lymphoma,” first author Tanya Siddiqi, MD, associate professor in the division of lymphoma, City of Hope National Medical Center, Duarte, Calif., said in a press statement in connection with her presentation at the annual meeting of the American Society of Clinical Oncology.

“The durable complete responses observed with liso-cel in the TRANSCEND CLL 004 trial are remarkable and represent a major step in bringing a personalized, T cell–based treatment approach delivered as a one-time infusion into clinical practice for a complex and historically incurable disease,” she said.

Real-world evidence shows that patients with CLL or SLL who have relapsed or are refractory to treatment with BTKi therapy can have progressively worse outcomes. Moreover, with few other treatment options, research shows that the median time from dual discontinuation of BTKi and venetoclax to subsequent treatment failure or death is just 5.6 months.

“We are seeing a subset of patients now who are progressing on BTK inhibitors and venetoclax, and there is a high, unmet medical need for new, more effective treatments in this patient population,” Dr. Siddiqi said.

With liso-cel showing efficacy in the treatment of large B-cell lymphoma and receiving approval from the Food and Drug Administration for the indication, the multicenter TRANSCEND CLL 004 trial was launched to investigate the therapy’s effects in r/r CLL/SLL.

In a safety set of 117 patients with r/r CLL or SLL who received at least two prior lines of therapy, including a BTKi, patients received a single target dose of either 50 (n=9) or 100 × 106 (n = 87) CAR-positive T cells.

The primary efficacy analysis set included 49 patients who were treated with the target dose of 100 x 106 CAR-positive viable T cells of liso-cel.

With a median on-study follow-up of 21.1 months, the primary endpoint of a complete response (CR) and complete response was achieved among 18.4% (n = 9; P = .0006).

Among patients achieving a complete response, no disease progression or deaths were reported, with a median duration of response that was not reached.

The undetectable minimal residual disease (MRD) rate was 63.3% in blood and 59.2% in bone marrow, which was associated with progression-free survival.

The overall response rate was 42.9%, which was not statistically significant, and the median duration of an objective response was 35.3 months (95% confidence interval, 11.01 to not reached).

The median time to first response was 1.2 months, and the median time to first complete response was 3.0 months.

The results were consistent in the broader safety set of 117 patients, including those who were heavily pretreated with a median of five prior lines of therapy (range, 2-12) and high-risk disease, with a CR rate of 18.4%.

In terms of safety, no new safety signals were observed, and the treatment’s safety profile was manageable, the authors noted.

Cytokine release syndrome (CRS), common with CAR T-cell therapy, occurred in 85% of patients; however, most cases were low grade; 9% of cases were grade 3, and there were no grade 4 or 5 cases.

Neurologic events occurred among 45%, including grade 3 in 17.9% and grade 4 in 0.9%, with no cases of grade 5.

For treatment of the CRS, 69.2% of patients received tocilizumab and/or corticosteroids for the cases of CRS and neurological events.

Of 51 deaths that occurred while on the study, 43 occurred following liso-cel infusion, including 5 caused by treatment-emergent adverse events occurring within 90 days of liso-cel infusion.

One death was determined to be related to liso-cel, involving macrophage activation syndrome–hemophagocytic lymphohistiocytosis.

“The safety profile was manageable, with low rates of grade 3 or higher CRS and neurotoxicity,” Dr. Siddiqi said.

She noted that, as encouraging as the results are, work should continue regarding further improving survival for patients.

“We need to look at this population more closely to see how we can make it even better for them,” she said in her talk.

For instance, “do we need to add maintenance, or do we need to do something else with CAR T therapy? Because one shot of CAR T is buying them a lot of time – 6 or 12 months of progression-free survival, but maybe we can make it even better.”

Dr. Siddiqi noted that she has “a lot of patients” who received CAR T-cell therapy who have not progressed or relapsed after as long as 4 years.

“I also have some patients who did relapse at 3 or 3 and 1/2 years, but everybody is so thankful for having that time of several years without any treatment; without the need for continuous therapy or continuous doctors’ visits. It is actually priceless,” she said.

Largest data set to date

Commenting on the study, Jakub Svoboda, MD, agreed that the findings suggest an important role of liso-cel among the growing numbers of patients who progress despite standard therapies.

“This is an important study and the [results] are very relevant as there is a growing population of patients with CLL/SLL who stopped responding to both BTKi and venetoclax and have limited options,” Dr. Svoboda, a medical oncologist at Penn Medicine, and associate professor of medicine at the Hospital of the University of Pennsylvania, both in Philadelphia, said in an interview.

“Many of my CLL/SLL patients benefited from BTK inhibitors and venetoclax for years, but it is clear that these are not curative agents, and ultimately our patients need other effective therapeutic options,” he said. “We have seen reports of smaller single-site studies with different anti-CD19 CAR T-cell products used in CLL/SLL in the past, but this multisite study using liso-cel represents the largest data set in over 100 patients with median follow-up of 21 months.”

Liso-cel, like other CAR T-cell treatments – which are derived from patients’ own cells that are then reengineered and delivered via a one-time infusion – has a 4-1BB costimulatory domain. This has the effect of enhancing the expansion and persistence of the CAR T cells.

Significantly, the study establishes that CAR T-cell manufacturing in CLL/SLL patients is feasible on a large scale, “which is important, considering the unique T-lymphocyte biology in CLL/SLL,” Dr. Svoboda remarked.

In terms of efficacy, “I have been mostly impressed by the high degree of undetectable minimal residual disease and the duration of response in the cohort of patients who previously failed both BTKi and venetoclax,” he added. “While there are a few agents used or being developed for patients failing both BTKi and venetoclax, it appears that CAR T-cell therapy has the unique potential to achieve long-term remissions in a subset of these patients.”

Discussant Carolyn Owen, MD, an associate professor in the division of hematology and hematological malignancies, University of Calgary (Alta.), and hematologist at the Tom Baker Cancer Centre, also in Calgary, also expressed enthusiasm over the encouraging results.

“The results of this study are very exciting,” she said during her discussion in the session.

“What is really important is that, even though this may be a small proportion of all of the patients, if we start offering this therapy a little bit earlier, and don’t wait for people to become completely refractory, we could increase the proportion of patients who are [not relapsing].”

Furthermore, “what’s most groundbreaking about this study is that patients could indeed have a really durable remission,” Dr. Owen added. “Hopefully not relapsing even beyond this 20-month follow up, which we haven’t seen with any of our other therapies.”

The results were also published in The Lancet.

The study was sponsored by Juno Therapeutics. Dr. Siddiqi disclosed relationships with Acerta Pharma, Ascentage Pharma, AstraZeneca, BeiGene, Bristol-Myers Squibb/Sanofi, Celgene, Juno Therapeutics, Kite, Oncternal Therapeutics, Pharmacyclics, and TG Therapeutics. Dr. Svoboda reported ties with Bristol-Myers Squibb. Dr. Owen disclosed relationships with Janssen, AstraZeneca, Roche Canada, AbbVie, Novartis Canada Pharmaceuticals, BeiGene, Merck, Incyte, and Seagen.

This article originally appeared on MDedge.com, part of the Medscape Professional Network.

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