Image-Guided Interventional Radiological Delivery of Chimeric Antigen Receptor (CAR) T Cells for Pleural Malignancies in a Phase I/II Clinical Trial

TPS7568 Background: Despite the recent progress in the therapy of CLL with BTK, PI3Kδ, and BCL2 inhibitors, CLL remains incurable and patients with high-risk disease features (i.e. del17p, complex karyotype) and patients whose disease progress after treatment with the above targeted agents continue to have extremely poor prognosis. CD19-specific chimeric antigen receptor (CAR) T cell therapy with various 2nd generation CARs (19-28z or 19-41BBz) have demonstrated anti-tumor efficacy in CLL but the complete response (CR) rates in CLL have been suboptimal (20-45%) compared to CR rates in ALL (80-90%). The suboptimal activity of the current 2nd generation CAR T cells can be due to the inhibitory tumor microenvironment (TM) of CLL. We believe one approach to over the hostile TM is through the use of CD19-CAR T cells further modified to express a second costimulatory ligand, 4-1BBL. A binding of 4-1BBL to its cognate receptor enhances T cell proliferation, IL-2 secretion, and survival and cytolytic activity of the T cells compared to 19-28z. 19-41BBz and 1928BBz (Zhao Z et al. Cancer Cell 2015;28:415-428). Methods: This phase I dose escalating trial is a single-center clinical trial (MSKCC) to study the safety and efficacy of autologous EGFRt/19-28z/4-1BBL+ CAR T cells in patients with relapsed CLL. Given the concern for potential systemic toxicity the vector includes a "safety switch" in the form of a gene for the expression of truncated form of human epidermal growth factor receptor (EGFRt). Patients with relapsed CLL are eligible for the trial. Patients will receive conditioning chemotherapy of cyclophosphamide followed by escalating doses of CAR T cells (1x105 – 3x106 CAR T cells/kg). The primary endpoint is safety and maximum tolerated doses of the CAR T ells. Secondary objectives include response assessment by iwCLL criteria. The comprehensive treatment algorithms for CRS and neurotoxicity are based on our CAR T cell experience in other studies. The study will begin enrollment in February 2017 and enroll up to 30 patients. Clinical trial information: Pending.

e20021 Background: Anti-CD19 chimeric antigen receptor (CAR) T cells for relapse/refractory B-cell malignancies has been remarkably effective in previous clinical trials. However, most of subjects has severe adverse effect even though the infusion of CAR T cells is at the low dose. Herein, we investigated the safety of administering CAR T cells which express the anti-CD19 chimeric antigen receptor in synthetic biology optimizing system. Methods: We designed an anti-CD19 CAR with FMC63 Scfv (KD-019). This CAR has a CD8 hinge and transmembrane domains and a 4-1BB costimulatory domain; T cells expresses CAR in synthetic biology optimizing system. A phase I dose-escalation trial was conducted to investigate the safety of KD-019 CAR T cells and to assess efficacy for patients with previously treated B-cell lymphoma. The patient at the 76 years old received Flu/Cy chemotherapy to enhance CAR T cells activity. Two days after the completion of chemotherapy, about 3 million KD-019 CAR T cells were infused. Results: The patient who has chemotherapy-refractory lymphoma has received KD-019 CAR T cells infusion. Post infusion KD-019 CAR T cells expansion were observed; peak CAR T cells level occurred between Day 3 and 10, and CAR T cells were still detected on Day 243. In addition, we found that CD3+CD8+ T cells level peaked on Day 15. Moreover, after infusion of CAR-T cells, the right peripheral pulmonary lymphaden and visible nodules were respectively shrunk by 53% and 85% on Day 28; and some peripheral pulmonary nodules were obviously reduced and nearly disappeared. We also found that pelvic effusion was significantly reduced, and pain symptoms of the left hip and leg were reduced by 50%. Exhilaratingly, our KD-019 CAR therapy has no obvious cytokine release syndrome (CRS) and central nervous system toxicity. Conclusions: KD-019 CAR T cells express an anti-CD19 chimeric antigen receptor in synthetic biology optimizing system. this innovative KD-019 product can offer significant clinical benefit for NHL patients at the low dose without fever and neurotoxicity. Clinical trial information: NCT03854994. Clinical trial information: NCT03854994 .

BackgroundChimeric antigen receptor (CAR)-T therapy has yielded impressive clinical results in hematological malignancies and it is a promising approach for solid tumor treatment. However, toxicity, including on-target off-tumor antigen binding, is a concern hampering its broader use.MethodsIn selecting a lead CAR-T candidate against the oncofetal antigen glypican 3 (GPC3), we compared CAR bearing a low and high affinity single-chain variable fragment (scFv,) binding to the same epitope and cross-reactive with murine GPC3. We characterized low and high affinity CAR-T cells immunophenotype and effector function in vitro, followed by in vivo efficacy and safety studies in hepatocellular carcinoma (HCC) xenograft models.ResultsCompared to the high-affinity construct, the low-affinity CAR maintained cytotoxic function but did not show in vivo toxicity. High-affinity CAR-induced toxicity was caused by on-target off-tumor binding, based on the evidence that high-affinity but not low-affinity CAR, were toxic in non-tumor bearing mice and accumulated in organs with low expression of GPC3. To add another layer of safety, we developed a mean to target and eliminate CAR-T cells using anti-TNFα antibody therapy post-CAR-T infusion. This antibody functioned by eliminating early antigen-activated CAR-T cells, but not all CAR-T cells, allowing a margin where the toxic response could be effectively decoupled from anti-tumor efficacy.ConclusionsSelecting a domain with higher off-rate improved the quality of the CAR-T cells by maintaining cytotoxic function while reducing cytokine production and activation upon antigen engagement. By exploring additional traits of the CAR-T cells post-activation, we further identified a mechanism whereby we could use approved therapeutics and apply them as an exogenous kill switch that would eliminate early activated CAR-T following antigen engagement in vivo. By combining the reduced affinity CAR with this exogenous control mechanism, we provide evidence that we can modulate and control CAR-mediated toxicity.Ethics ApprovalAll animal experiments were conducted in a facility accredited by the Association for Assessment of Laboratory Animal Care (AALAC) under Institutional Animal Care and Use Committee (IACUC) guidelines and appropriate animal research approval.

AbstractColorectal cancer (CRC) is the third most common cancer and the second leading cause of cancer deaths worldwide. Besides common therapeutic approaches, such as surgery, chemotherapy, and radiotherapy, novel therapeutic approaches, including immunotherapy, have been an advent in CRC treatment. The immunotherapy approaches try to elicit patients` immune responses against tumor cells to eradicate the tumor. Monoclonal antibodies (mAbs) and chimeric antigen receptor (CAR) T cells are two branches of cancer immunotherapy. MAbs demonstrate the great ability to completely recognize cancer cell-surface receptors and blockade proliferative or inhibitory pathways. On the other hand, T cell activation by genetically engineered CAR receptor via the TCR/CD3 and costimulatory domains can induce potent immune responses against specific tumor-associated antigens (TAAs). Both of these approaches have beneficial anti-tumor effects on CRC. Herein, we review the different mAbs against various pathways and their applications in clinical trials, the different types of CAR-T cells, various specific CAR-T cells against TAAs, and their clinical use in CRC treatment.