Fully human heavy chain variable (FHVH) antibodies that specifically target CD5 or CD7 were screened and
constructed to CD5/CD7 bispecific CARs. A truncated Epidermal growth factor receptor were integrated into CAR constructs to
address safety concerns. To tackle the fratricidal issue of CAR-T cells targeting T-cell-pan marker(s), CRISPR/Cas9-based CD5 and CD7
genes knockout were performed before lentiviral transduction of bispecific CARs.
Different from canonical drugs, CAR T-cells are “living drugs”, which derived from patient’s own blood. Studies of the pharmacokinetics of CAR T-cells could improve our understanding of their efficacy, safety, optimal dosage, and other characterizes. We previously reported a phase I study of a novel fully human BCMA-targeting CAR (CT103A) in 18 patients with relapsed/refractory multiple myeloma. CT103A exhibited extraordinary persistence with low anti-drug antibody positivity. To figure out the pharmacokinetic characterizes and investigate the potential reason of CT103A’s long-term persistence, we established a population pharmacokinetic (PopPK) model of CT103A based on 18 patients cohort by applying nonlinear mixed-effects modeling and analyzed the CAR T-cell clonal evolution. The results suggested that extramedullary spreading was found to impair Cmax and was therefore added as a covariate to the modified model. The model revealed tocilizumab and corticosteroids showed no impact on the CT103A expansion rate. No dominant clone existed in patients with persistently high peripheral CT103A by CAR integration sites analysis. Finally, patients with lower contraction rate constants and higher Cmax as well as memory CT103A fraction could achieve better clinical responses. Taken together, this study developed a PopPK model of a fully human anti-BCMA CAR T-cell therapy, and summarized its model characteristics. We suggested that the long-term persistence of CT103A was attributed to the memory CAR T-cell fraction but not the clonal evolution. This study will improve people’s understanding of pharmacokinetics and PopPK of CAR T-cell immunotherapy.
T cell malignancies are a group of hematologic cancers with high recurrence and mortality rates. CD5 is highly expressed in 85% of T cell malignancies, although normal expression of CD5 is restricted to thymocytes, T cells, and B1 cells. However, CD5 expression on chimeric antigen receptor (CAR)-T cells leads to CAR-T cell fratricide. Once this limitation is overcome, CD5-targeting CAR-T therapy could be an attractive strategy to treat T cell malignancies. Here, we report the selection of novel CD5-targeting fully human heavy-chain variable (FHVH) domains for the development of a biepitopic CAR, termed FHVH3/VH1, containing FHVH1 and FHVH3, which were validated to bind different epitopes of the CD5 antigen. To prevent fratricide in CD5 CAR-T cells, we optimized the manufacturing procedures of a CRISPR-Cas9-based CD5 knockout (CD5KO) and lentiviral transduction of anti-CD5 CAR. In vitro and in vivo functional comparisons demonstrated that biepitopic CD5KO FHVH3/VH1 CAR-T cells exhibited enhanced and longer lasting efficacy; produced moderate levels of cytokine secretion; showed similar specificity profiles as either FHVH1, FHVH3, or the clinically tested H65; and is therefore suitable for further development.
B-cell maturation antigen (BCMA)-specific chimeric antigen receptor (CAR) T-cell therapies have shown efficacy in relapsed/refractory multiple myeloma (RRMM). Because the non-human originated antigen-targeting domain may limit clinical efficacy, we developed a fully human BCMAspecific CAR, CT103A, and report its safety and efficacy in a phase 1 trial. Eighteen consecutive patients withRRMM, including 4 with priormurine BCMACAR exposures, were enrolled. CT103A was administered at 1, 3, and 6×106 CAR-positive T cells/kg in the dose-escalation phase, and 1×106 CAR-positive T cells/kg in the expansion cohort. The overall response rate was 100%, with 72.2% of the patients achieving complete response or stringent complete response. For the 4 murine BCMA CAR–exposed patients, 3 achieved stringent complete response, and 1 achieved a very good partial response. At 1 year, the progression-free survival ratewas 58.3% for all cohorts and 79.1% for the patients without extramedullary myeloma. Hematologic toxicities were the most common adverse events; 70.6% of the patients experienced grade 1 or 2 cytokine release syndromes.No immune effector cell–associated neurotoxicity syndrome was observed. To the cutoff date, CAR transgenes were detectable in 77.8% of the patients. The median CAR transgene persistence was 307.5 days. Only 1 patient was positive for the anti-drug antibody. Altogether, CT103A is safe and highly active in patients with RRMMand can be developed as a promis-ing therapy for RRMM. Patients who relapsed from prior murine BCMA CAR T-cell therapy may still benefit from CT103A. This trial was registered at http://www.chictr.org.cn as #ChiCTR1800018137. (Blood. 2021;137(21):2890-2901)
In this issue of Blood, Wang et al report their phase 1 trial of CT103, a fully human 4-1BBζ chimeric antigen receptor (CAR) targeting the B-cell maturation antigen (BCMA), in 18 patients with relapsed or refractory multiple myeloma (MM).1
Literature review of MSCs in the treatment of osteoarthritis in the past five years: Osteoarthritis (OA) is one of the most common chronic joint diseases, with prominent symptoms caused bymany factors. However, current medical interventions for OA have resulted in poor clinical outcomes, demonstrating that there are huge unmet medical needs in this area. Cell therapy has opened new avenues of OA treatment. Different sources of mesenchymal stromal cells (MSCs) may have different phenotypes and cellular functions. Pre-clinical and clinical studies have demonstrated the feasibility, safety and efficacy of MSC therapy. Mitogen-activated protein kinase, Wnt and Notch signaling pathways are involved in the chondrogenesis ofMSC-mediated treatments. MSCs may also exert effective immunoregulatory and paracrine effects to stimulate tissue repair. Therapy with extracellular vesicles containing cytokines, which are secreted by MSCs,might be a potential treatment for OA. © 2021 International Society for Cell & Gene Therapy. Published by Elsevier Inc. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)
CD22-targeted chimeric antigen receptor (CD22-CAR) T cells have been proven to be effective in treating patients with B acute lymphoblastic leukemia (B-ALL) who were unsuitable to receive CD19-CAR T cell therapy1,2,3. However, a considerable proportion of patients still relapsed after CD22-CAR T cell therapy3,4, with diminished or decreased levels of CD22 expression on blasts. For patients who had not completely lost CD22 expression on blasts, CD22-CAR T cell re-treatment may apply as a salvage regimen. But unfortunately, in a previous trial on a humanized CD22-CAR (termed CD22-CARYK002) T cell therapy, a second CD22-CARYK002 infusion produced no or suboptimal anti-leukemia response and CAR T cell expansion (Table S1 and Fig. S1). Because the immunogenicity of humanized antibodies or CARs has been suggested in previous studies5,6,7,8, the poor effect of the second CD22-CARYK002 infusion might be due to the patient’s immune response against CD22-CARYK002 transgene. On the other hand, CD22 downregulation might also represent a mechanism of resistance to a second CAR T-cell therapy3. Therefore, a new CD22-CAR with no cross immunogenicity with CD22-CARYK002, and with strong activity against CD22low cells, may be effective for the second treatment of patients who failed from previous CD22-CARYK002 T cell therapy. Furthermore, since the immunogenicity of full-human antibodies tends to be reduced compared with humanized or chimeric constructs9,10,11, the usage of fully human-derived CAR constructs might be a better strategy, which can further lower the risk of developing immune responses against the secondarily infused CAR T cells.
Impressive outcomes have been achieved by chimeric antigen receptor (CAR)‐T cell therapy using murine‐derived single‐chain variable fragment (scFv) FMC63 specific for CD19 in patients with B cell malignancies. However, evidence suggests that human anti‐mouse immune responses might be responsible for poor persistence and dysfunction of CAR‐T cells, leading to poor outcomes or early tumor recurrence. Substituting a fully human scFv for murine‐derived scFv may address this clinically relevant concern. In this study, we discovered two human anti‐CD19 scFv candidates through an optimized protein/cell alternative panning strategy and evaluated their function in CAR‐T cells and CD19/CD3 bispecific antibody formats. The two clones exhibited excellent cytotoxicity in CAR‐T cells and bispecific antibodies in vitro compared with the benchmarks FMC63 CAR‐T cells and blinatumomab. Furthermore, Clone 78‐BBz CAR‐T cells exhibited similar in vivo antitumor activity to FMC63‐BBz CAR‐T cells. Our results indicate that Clone 78‐BBz CAR has excellent efficacy and safety profile and is a good candidate for clinical development.