CAR T-Cell Therapies Are Set to Expand Into More Hematologic Malignancy Indications

Michael Wang, MD

Multiple chimeric antigen receptor (CAR) T-cell therapies for the treatment of lymphomas and multiple myeloma have moved forward in the regulatory process, with 1 new FDA approval in 2020 and others anticipated in the near future.

In July, brexucabtagene autoleucel (Tecartus; KTEX19) received accelerated approval for the treatment of adult patients with relapsed or refractory mantle cell lymphoma (MCL) based on the results of the phase 2 ZUMA-2 trial (NCT02601313), bringing the treatment landscape of this hematologic malignancy into a new era.¹

“This approval is only the very beginning, and we are walking into a sophisticated CAR T-cell therapy era with many constructs being designed with [different mechanisms of action],” Michael Wang, MD, said in an interview with Targeted Therapies in Oncology (TTO).

Additional actions by the FDA this year included granting priority review designations to lisocabtagene maraleucel (liso-cel) for the treatment of adult patients with relapsed or refractory (R/R) large B-cell lymphoma, after at least 2 prior therapies,² as well as to idecabtagene vicleucel (ide-cel; bb2121) as treatment of adult patients with multiple myeloma who have received at least 3 prior therapies, including an immunomodulatory drug (IMiD), a proteasome inhibitor (PI), and an anti-CD38 antibody.³

Brexucabtagene Autoleucel

The approval of brexucabtagene autoleucel, an antiCD19 CAR T-cell product, in MCL was based on objective response rate (ORR) data from patients treated on a single-arm trial who had previously received anthracycline- or bendamustine-containing chemotherapy, an anti-CD20 antibody, and a Bruton tyrosine kinase inhibitor (n = 74).^2,4 Eligible patients received leukapheresis and optional bridging therapy, followed by conditioning chemotherapy and a single infusion of brexucabtagene autoleucel 2 × 10⁶ CAR T cells/kg.

The results of ZUMA-2 were published in the New England Journal of Medicine in April and demonstrated a 93% (95% CI, 84%-98%) ORR in 60 response-evaluable patients, 67% (95% CI, 53%-78%) of whom had a complete response (CR). ORRs were consistent across key patient subgroups. Two patients (3%) each had stable and progressive disease.

Progression-free and overall survival (OS) rates at 12 months were 61% and 83%, respectively, and 57% of patients remained in remission at the 12.3-month median follow-up.⁴ Cytokine release syndrome (CRS) was the most concerning adverse event, occurring in 91% of patients; grade 3 or higher CRS occurred in 15%.

Notably, the patient cohort comprised patients with a median of 3 prior lines of therapy (range, 1-5) and more than half (56%) were considered to have intermediateor high-risk features by the simplified Mantle Cell Lymphoma International Prognostic Index at baseline.

“Before CAR T-cell therapy, we did not have any effective means [of getting patients with high-risk MCL into remission]. We used allogeneic transplantation [and] were able to put some of the patients into a long-term remission, but at a heavy price of mortality,” said Wang, a professor in the Department of Lymphoma & Myeloma, Division of Cancer Medicine at The University of Texas MD Anderson Cancer Center in Houston. “Overall, this brings hope to the high-risk patient population. It looks as though fewer patients are relapsing.”

Lisocabtagene Maraleucel In February, the FDA granted liso-cel a priority review designation, an action supported by the safety and efficacy findings of the phase 1 TRANSCEND-NHL-001 trial (NCT02631044).²

Histologic subtypes eligible for treatment included diffuse large B-cell lymphoma (DLBCL); high-grade double- or triple-hit B-cell lymphoma; transformed DLBCL from indolent lymphoma; primary mediastinal B-cell lymphoma; and grade 3B follicular lymphoma. Patients were administered 2 sequential infusions of CD8+ and CD4+ CAR T cells following optional bridging therapy and lymphodepleting chemotherapy and were assigned to 1 of 3 target dose levels: 50 ×10⁶ (1 or 2 doses), 100 ×10⁶ , or 150 ×10⁶ CAR-positive T cells. Investigators determined that the recommended target dose was 100 ×10⁶ CAR-positive T cells.

Carlos R. Bachier, MD

In the 256 patients who received at least 1 dose of liso-cel and were included in the efficacy-evaluable group, the ORR was 73% (95% CI, 67%-78%), with 53% (95% CI, 47%-59%) achieving a CR. Investigators observed all-grade CRS (42%) and neurological events (30%), but most cases were grade 1 or 2 in severity.

Due to relatively low rates of CRS and neurological events, the administration of liso-cel has been explored in both the inpatient and outpatient settings. One that included a cohort of patients treated in the outpatient setting with proper monitoring versus the traditional inpatient setting demonstrated consistent safety.⁶

“Based on these results, the indication is that you can deliver [liso-cel] in the outpatient setting and the outcomes are good compared with those treated in the inpatient setting,” explained study author Carlos R. Bachier, MD, the director of cellular research at Sarah Cannon in Nashville, Tennessee, in an interview with TTO. “Aside from that, they also showed that liso-cel could be safely administered outside of university programs and in more community-based programs, most of them being aligned [with] or part of stem cell and bone marrow transplant programs.”

The target action date for a decision on the biologics license application (BLA) for liso-cel was extended twice in 2020 and remains under review. In May, the FDA moved the Prescription Drug User Fee Act (PDUFA) goal date out 3 months from its original August deadline.^2,7 Bristol Myers Squibb, the company responsible for developing the product, submitted additional information to the agency following the initial BLA submission, which resulted in more review time. Once again, the target action date was pushed in November, this time due to incomplete manufacturing facility inspections resulting from ongoing travel restrictions due to COVID-19. The FDA provided no new action date.⁸

Idecabtagene Vicleucel

For patients with multiple myeloma, the B-cell maturation antigen (BCMA)-targeting CAR T-cell therapy idecel is currently under review for approval in patients who have received at least 3 prior therapies—including an immunomodulatory drug (IMiD), a proteasome inhibitor (PI), and an anti-CD38 antibody—based on results of the phase 2 KarMMa trial (NCT03361748).⁹

Updated trial results were presented at the American Society of Clinical Oncology 2020 Virtual Scientific Program, and showed that both the primary and key secondary end points of ORR and CR rate were 75% and 33%, respectively. The median duration of response was 10.7 months, and the median progression-free survival was 8.8 months in all patients receiving ide-cel. Corresponding medians were 19.0 and 20.2 months among those achieving a CR or stringent CR. The median OS was 19.4 months in all treated patients.

The 128 patients treated received 1 of 3 target dose levels: 150, 300, or 450 × 10⁶ CAR-positive T cells. The investigators noted that the highest efficacy outcomes were seen in patients in the 450 × 10⁶ CAR-positive T-cell group, with an ORR of 82% and a 39% CR rate.

The incidence of CRS was 84% across the treatment cohort and increased with higher target doses. Overall, less than 6% of patients have grade 3 or higher CRS and only 1 patient in the highest target dose cohort had a grade 5 event. Neurological toxicity was low across target doses, with no grade 4 or 5 events reported.

At baseline, the majority of patients (51%) had high tumor burden, 39% had extramedullary disease, and 35% had high-risk cytogenetics including deletion 17p or translocations in t(4;14) or t(14;16).

In May, the FDA issued a refusal letter regarding the BLA for ide-cel because the Chemistry, Manufacturing, and Control (CMC) module required more information before they could complete the review.¹⁰ In September, the resubmitted application received a priority review and the agency assigned a PDUFA action date of March 27, 2021.¹¹

If approved, ide-cel would be the first CAR T-cell therapy available for the treatment of patients with multiple myeloma.

_References:

_{1. FDA approves brexucabtagene autoleucel for relapsed or refractory mantle cell lymphoma. FDA. Updated July 27, 2020. Accessed November 18, 2020. https://bit. ly/3pEDQV5}

_{2. US Food and Drug Administration (FDA) accepts for priority review Bristol-Myers Squibb’s biologics license application (BLA) for lisocabtagene maraleucel (liso-cel) for adult patients with relapsed or refractory large B-cell lymphoma. Press release. Bristol Myers Squibb. February 13, 2020. Accessed November 18, 2020. https:// bit.ly/37ruQbs}

_{3. US Food and Drug Administration (FDA) accepts for priority review Bristol Myers Squibb and bluebird bio application for anti-BCMA CAR T cell therapy idecabtagene vicleucel (ide-cel, bb2121). Press release. Bristol Myers Squibb. September 22, 2020. Accessed November 18, 2020. https://bit.ly/3kDhakH}

_{4. Wang M, Munoz J, Goy A, et al. KTE-X19 CAR T-cell therapy in relapsed or refractory mantle-cell lymphoma. N Engl J Med. 2020;382(14):1331-1342. doi:10.1056/ NEJMoa1914347}

_{5. Abramson JS, Palomba ML, Gordon LI, et al. Lisocabtagene maraleucel for patients with relapsed or refractory large B-cell lymphomas (TRANSCEND NHL 001): a multicentre seamless design study. Lancet. 2020;396(10254):839-852. doi:10.1016/ S0140-6736(20)31366-0}

_{6. Bachier CR, Palomba ML, Abramson JA, et al. Outpatient treatment with lisocabtagene maraleucel (liso-cel) in 3 ongoing clinical studies in relapsed/refractory (R/R) large B cell non-Hodgkin lymphoma (NHL), including second-line transplant noneligible (TNE) patients: Transcend NHL 001, Outreach, and PILOT. Paper presented at: 2020 Transplantation & Cellular Therapy Meetings; February 19-23, 2020; Orlando, FL. Abstract 29. Accessed November 18, 2020. bit.ly/37I7DC9}

_{7. Bristol Myers Squibb provides update on biologics license application (BLA) for lisocabtagene maraleucel (liso-cel). Press release. Bristol Myers Squibb. May 6, 2020. Accessed November 18, 2020. https://bit.ly/2YFWAs8}

_{8. Bristol Myers Squibb provides regulatory update on lisocabtagene maraleucel (liso-cel). News release. Business Wire. November 16, 2020. Accessed November 18, 2020. https://bwnews.pr/3pKQMZI}

_{9. Bristol Myers Squibb and bluebird bio announce submission of biologics license application (BLA) for anti-BCMA CAR T cell therapy idecabtagene vicleucel (ide-cel, bb2121) to FDA. Press release. Bristol Myers Squibb. March 31, 2020. Accessed November 18, 2020. https://bit.ly/2JwKbxO}

_{10. Bristol Myers Squibb and bluebird bio provide regulatory update on idecabtagene vicleucel (ide-cel, bb2121) for the treatment of patients with multiple myeloma. News release. Business Wire. May 13, 2020. Accessed November 18, 2020. https:// bwnews.pr/3cpgJa1}

_{11. US Food and Drug Administration (FDA) accepts for priority review Bristol Myers Squibb and bluebird bio application for anti-BCMA CAR T cell therapy idecabtagene vicleucel (ide-cel, bb2121). Press release. Bristol Myers Squibb. September 22, 2020. Accessed November 18, 2020. https://bit.ly/3kDhakH}