Re-directed T cells for the treatment of fibroblast activation protein (FAP)-positive malignant pleural mesothelioma (FAPME-1)

Abstract

Background: Asbestos is the main cause of MPM in industrialized countries. Even since asbestos is banned in most developed countries, the peak wave of MPM incidence is anticipated for the next years due to the long latency of asbestos induced MPM. MPM patients not eligible for surgical procedures like decortication or pleuro-pneumectomie have a median survival of 12 months with palliative chemotherapy. Therefore, new therapeutic approaches are of crucial need in this clinical situation.

Methods/design: This is a phase I trial for patients with malignant pleural mesothelioma with pleural effusion testing the safety of a fixed single dose of 1x106 adoptively transferred FAP-specific re-directed T cells given directly in the pleural effusion. Lymphocytes will be taken 21 days before transfer from peripheral blood. CD8 positive T cells will be isolated and re-programmed by retroviral transfer of a chimeric antigen receptor recognizing FAP which serves as target structure in MPM. At day 0 of the protocol, re-directed T cells will be injected in the pleural effusion and patients will be monitored for 48h under intermediate care conditions. AE, SAE, SADR and SUSAR will be monitored for 35 days and evaluated by an independent safety board to define any dose limiting toxicity (DLT). No further patient can be treated before the previous patient passed day 14 after T cell transfer. The protocol will be judged as save when no DLT occurred in the first 3 patients, or 1 DLT in 6 patients. Secondary objectives are feasibility and immune monitoring.

Discussion: Adoptive T cell transfer is a new and rapidly expanding branch of immunotherapies focusing on cancer treatment. Recently, objective responses could be observed in patients with chronic lymphatic leukemia treated with adoptively transferred CD19-specific re-directed T cells. The choice of the target antigen determines the possible on-target off-tissue toxicity of such approaches. There are reports of severe toxicity in patients who received T cells intravenously due to unexpected expression of the target antigen (on-target) in other tissues than the tumor (off-tissue). To minimize the risk of on-target off-tissue toxicity and to maximize the on-target anti-tumor effect we propose a clinical protocol with loco-regional administration of re-directed T cells. FAP-specific T cells will be directly injected in the pleural effusion of patients with MPM.

Trial registration: ClinicalTrials.gov (NCT01722149).

Figures

Figure 1

For the evaluation of the expression of FAP in MPM immunofluorescence (IF) microscopy was performed with the F19 antibody (A, C) or an irrelevant anti-CD20 antibody only (B, D). Epithelioid (A, B) and sarcomatoid (C, D) MPM were analyzed. FAP staining is depicted in green. Cell nuclei were stained with DAPI (blue).

Figure 2

The chimeric antigen receptor F19 is a fusion protein which consists of four functional domains. The scFv F19 serves as binding domain and binds to FAP. The IgG Fc-domain functions as a spacer (hinge); the CD28 signalling domain leads to co-stimulation and the CD3ζ signalling domain activates the T cell if the receptor is cross-linked via antigen binding. The CAR will be expressed in CD8 positive T cells with unknown endogenous specificity.

Figure 3

(A) Adoptive transfer of re-directed T cells: (1) 250 ml blood withdrawal at day −21, (2) separation of CD8+ T cells, (3) retroviral transduction of the CAR (+) specific for FAP, (4) adoptive transfer of re-directed T cells day 0. (B) Study course: As concomitant palliative therapy chemotherapy with cycles of 21 days will be given before and after adoptive transfer. Re-directed T cells will be given 14 days after third cycle of palliative chemotherapy into the pleural effusion. Blood draw of 250 ml blood will be performed at day −21 for the production or re-directed T cells. Patients will be continuously monitored at an intermediate care unit (ICU) for the first 48h after the adoptive transfer of re-directed T cells into the pleural effusion (day 0). 30 min before the application of the re-directed T cells 16 mg Dexamethason will be given i.v. as pre-medication. The fourth cycle of palliative chemotherapy will be started 14 days after transfer. Palliative chemotherapy is not part of the study protocol. Radiation therapy is not permitted. Pleurodesis is not allowed until completion of the study. Supportive or other palliative measures are permitted without any exceptions. (C) CT scan of the thorax of a patient with MPM. The tumor nodules are attached to the pleural causing pleural effusion. The schematic syringe represents the application of the re-directed T cells in the pleural infusion resulting in a proximity of re-directed T cells and tumor.