A Phase II, Open-Label, Single Arm Trial to Assess the Efficacy and Safety of the Combination of Tisagenlecleucel and Ibrutinib in Mantle Cell Lymphoma (TARMAC)

Background

Mantle cell lymphoma (MCL) is a clinically and pathogenetically distinct B-cell non-Hodgkin lymphoma that presents at a median age of 65 years and typically at an advanced stage. High dose chemotherapy and stem cell transplantation can achieve durable responses, but disease eventually relapses in most patients. Allogeneic transplantation can achieve a cure in some but is only suitable for a minority of younger, fitter patients who achieve remission to salvage but carries risks of GVHD. Bruton tyrosine kinase inhibitors (BTKi) are active in relapsed MCL but the median PFS is generally less than 2 years and ibrutinib failure is associated with particularly poor outcomes (Cheah et al., Ann Oncol 2015). Mutations of TP53 are associated with refractoriness to both chemotherapy and novel agents (Eskelund et al., Blood 2017), and patients with disease harboring these mutations are in particular need of more effective therapies. Promising activity has recently been demonstrated with chimeric antigen receptor T-cells (CAR T), albeit with significant rates of cytokine release syndrome (CRS) and neurotoxicity (Wang et al., New England Journal of Medicine 2020), resulting in FDA approval of brexucabtagene autoleucel in MCL.

Rationale

Tisagenlecleucel (Novartis) is a CAR T-cell product directed against CD19 that is approved in many countries for the treatment of relapsed DLBCL and ALL. MCL consistently expresses CD19 at diagnosis and relapse and is therefore a promising target. Pre-clinical data suggests synergistic effects if tisagenlecleucel is combined with the BTKi ibrutinib. The proposed mechanism includes enhancing T cell activation and expansion (Fraietta et al., Blood 2016), disrupting the MCL nodal environment (Long et al., The Journal of Clinical Investigation 2017) and mitigating CRS (Ruella et al., Clin Cancer Res 2016). Clinical trials in CLL show that the combination is safe and effective, including deep minimal residual disease negative responses (Gill et al., Blood 2018, Gauthier et al., Hematological Oncology 2019).

We hypothesise that combination treatment will be tolerable and improve outcomes in a poor risk MCL population. Combination, time-limited therapy would also avoid the burdens of continuous treatment.

Study Design and Methods

20 adult patients with MCL that has relapsed following front-line therapy, or those patients with MCL with TP53 aberrations who have achieved less than complete response on PET imaging after 2 cycles of induction will be enrolled (See Fig 1. for inclusion and exclusion criteria). Treatment consists of 560mg oral ibrutinib followed by a single infusion of tisagenlecleucel. Autologous lymphocytes for CAR T manufacture will be collected after a minimum of 7 days of continuous ibrutinib therapy. Ibrutinib will be continued during CAR T manufacture and for 6 months after infusion (see Fig 2.)

Patient characteristics will be presented using descriptive statistics, response rates will be calculated as percentages using exact methods from the binomial distribution, and progression-free survival, duration of response and overall survival will be described using the Kaplan-Meier method.

The primary objective is to estimate the complete response (CR) rate at month 4 following tisagenlecleucel infusion in combination with ibrutinib with the primary endpoint being CR rates at month 4 post tisagenlecleucel using the Lugano criteria. Secondary objectives include estimating MRD negative response rates, response rates according to TP53 status, and safety of the combination. Exploratory translational studies include studies of T cell repertoire and phenotype during ibrutinib exposure and after tisagenlecleucel infusion. The role of circulating tumour DNA monitoring in the management of MCL is also being evaluated.

The trial is investigator led, sponsored by the Peter MacCallum Cancer Centre, with additional sites throughout Australia. The study was initiated in April 2020 and is actively recruiting patients.

The trial is registered at ClinicalTrials.gov: NCT04234061.