Key Design Elements of the Phase 3 Trial

INFLUENCE (NCT07223021) is an active, randomized, Phase 3 trial led by Memorial Sloan Kettering Cancer Center. It involves pediatric and young adult patients with relapsed/refractory B-cell acute lymphoblastic leukemia (B-ALL) who are eligible for standard Kymriah treatment. Patients will be divided into a standard fludarabine group and a pharmacokinetics-guided, target-exposure group. The primary endpoint is event-free survival (EFS), with secondary endpoints including 1- and 2-year overall survival, relapse, CAR-T persistence, toxicity, and quality of life. A key differentiator is that the trial focuses on validating the pre-conditioning protocol rather than the cell therapy itself.

Drug and Mechanism of Action

Kymriah (tisagenlecleucel) is a CD19-targeted autologous chimeric antigen receptor T-cell (CAR-T) therapy already marketed by Novartis AG (NOVN). Lymphoablation prior to infusion involves fludarabine (Fludara) and cyclophosphamide (Cytoxan), which reduce lymphocytes by inhibiting DNA polymerase and causing DNA alkylation, respectively. The control group receives standard fludarabine for four days, while the experimental group receives an initial two infusions followed by pharmacokinetic monitoring to adjust the remaining dose, targeting a mean exposure of AUC 18 mg·h/L. By accounting for individual renal function and drug clearance, this approach aims to create a more consistent immune environment that favors CAR-T expansion and persistence.

Clinical and Patient Implications

Both groups receive cyclophosphamide pre-conditioning followed by Kymriah infusion on day 0, with follow-up for up to 24 months. Key safety analyses include cytokine release syndrome (CRS), immune effector cell-associated neurotoxicity syndrome (ICANS), grade 3-4 cytopenias, and grade 3-5 infections. Therefore, this study addresses both improving efficacy and mitigating the toxicity associated with excessive fludarabine exposure, as well as CAR-T loss due to insufficient exposure. Positive results could allow for improved outcomes with existing Kymriah protocols through therapeutic drug monitoring (TDM) without requiring the development of new drugs.

Regulatory, Competitive, and Market Landscape

In July 2017, the FDA approved Kymriah for B-ALL following a 10-0 advisory committee vote, with approval dates from the EMA in August 2018 and the PMDA in March 2019. Competing products for adult B-ALL include Tecartus (brexucabtagene autoleucel) from Gilead Sciences (GILD) and Aucatzyl (obecabtagene autoleucel) from Autolus Therapeutics (AUTL), both of which are CD19-targeted, commercially available CAR-T therapies approved by the FDA on October 1, 2021, and November 8, 2024, respectively. Existing treatment options include Amgen's CD19/CD3 bispecific antibody, blinatumomab (Blincyto), the antibody-drug conjugate inotuzumab ozogamicin (Besponsa), and allogeneic hematopoietic stem cell transplantation. In 2024, the combined ALL treatment market in the US, EU4, UK, and Japan was estimated at USD 2.2705 billion, highlighting that standardizing pre-conditioning regimens can significantly impact CAR-T utilization and cost-effectiveness, even in limited patient populations.