Chimeric antigen receptor (CAR) T therapy represents a form of immune cellular therapy with clinical efficacy and a specific target. A typical chimeric antigen receptor (CAR) construct consists of an antigen binding domain, a transmembrane domain, and a cytoplasmic domain. Nanobodies have been widely applied as the antigen binding domain of CAR-T due to their small size, optimal stability, high affinity, and manufacturing feasibility. The nanobody-based CAR structure has shown a proven function in more than ten different tumor-specific targets. After being transduced in Jurkat cells, natural killer cells, or primary T cells, the resulting nanobody-based CAR-T or CAR-NK cells demonstrate anti-tumor effects both in vitro and in vivo. Interestingly, anti-BCMA CAR-T modulated by a single nanobody or bi-valent nanobody displays comparable clinical effects with that of single-chain variable fragment (scFv)-modulated CAR-T. The application of nanobodies in CAR-T therapy has been well demonstrated from bench to bedside and displays great potential in forming advanced CAR-T for more challenging tasks.

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8025 Background: Relapsed/refractory (RR) multiple myeloma (MM), RRMM, remains as an incurable disease and has a 5-year survival rate of nearly 50%. To address the unmet medical need, an autologous CAR-T cell therapy was developed previously with a humanized single-domain antibody (sdAb) targeting BCMA as the antigen binding domain, 4-1BB and CD3ζ as cytoplasmic domain. Methods: An investigator-initiated clinical trial (IIT) was conducted in China to assess the safety and efficacy of the sdAb-based CAR-T. The trail was started in June 2018 and the last patient infused in June 2019. As of 1 February 2021, 34 were treated and followed up. The patients had received multiple lines of prior treatment (including bortezomib, lenalidomide, and others). Following a lymphodepleting regimen of cyclophosphamide (300-600 mg/m2, d-5, -4) and fludarabine (25-30 mg/m2, d-5 to d-3), patients were infused with 2.5-10.0 × 106 CAR+ cells/kg body weight. CAR-T was infused immediately after preparation and quality control performed in all patients except one, who was infused a 10.0 × 106 CAR+ cells/kg dose of frozen cells. Efficacy was assessed based on the IMWG criteria, toxicity was graded by CTCAE 4.02, and CRS grading was based on the grading system by CARTOX working group. Results: All 34 patients had the tumor burden of plasma cells in bone marrow, or M protein or free light chains (FLCs) in serum, 7 patients were accompanied with extramedullary diseases. The efficacy shows the best ORR is 88.2% (30/34), sCR rate is 55.9% (19/34). The mPFS was 12.1 months, several patients shows continuous sCR after 2 years. No obvious correlation between efficacy and dosage were found in three dose groups of 2.5×106 CAR+ cells/kg (6 pts), 5.0×106 CAR+ cells/kg (23 pts) or 10.0×106 CAR+ cells/kg (5 pts). The observed adverse events include thrombocytopenia (≥grade 3, 38.2%), neutropenia (≥grade 3, 44.1%), leukopenia (≥grade 3, 32.4%), lymphopeniPa (≥grade 3, 26.5%), and anemia (≥grade 3, 20.6%). CRS was monitored occurring in 29 patients (any grade, 85.3%, ≥grade 3, 2.9%). Conclusions: Our result demonstrates that the CART employing one humanized sdAb targeting BCMA is safe and efficacious for clinical application. The phase I clinical trial has been initiated in China for searching the RP2D using the cryopreserved CAR-T cells. Clinical trial information: NCT03661554.

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Xenografting involves the transplantation of human tissue or cells into animal models and is an important tool for regenerative medicine research. Implantation of engineered human bone tissues into animal models, for example, is performed in preclinical evaluations of product safety and efficacy. With the advent of improved experimental methodologies, these models are further being exploited to interrogate molecular mechanisms and physiological interactions in vivo. In parallel to these developments, patient-derived xenograft murine models of cancer are increasingly being studied for various applications in cancer research and therapy; it follows that xenograft models in tissue engineering may be adapted for such approaches. In this review, we first discuss the development of human bone xenograft models to recapitulate physiological states in regenerative medicine. Subsequently, we discuss the use of these techniques for applications in modeling pathological states in skeletal oncology, namely, hematopoietic malignancies, bone metastatic disease, and primary bone malignancy.

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A monoclonal anti-human platelet antibody(MoAb), HIP2 (IgG3) which induced irrevesible aggregation of platelet in association with the release of serotonin and thromboxane B2 formation is described. Indirect immunofluorescence assay (IFS) showed that the antibody binded to platelets and megakryocytes, and gave a weak reaction with aortic, liver and capillary endothelial cells. Electrophoresis of radiolabelled antigen showed that HIP2 recognized platelet membrane glycoprotein lib (130KD). The purified HIP2 MoAb induced aggregation with normal PRP, not with thrombasthenia platelets, formalin-fixed platelets, washed platelets and EDTA-PRP. Washed platelet aggregation with HIP2 could be restored by adding normal plasma or serum into medium, but not by inactivated serum at 56°C for 30 minutes and fibrinogen, The results suggested that the aggregation induced by HIP2 needed Ca++ and complement in medium. HIP2-induced aggregation was completely inhibited by calmodulin inhibitor, compound 48/80, and partially inhibited by aspirin, apyrase, ATP, antimycin A and phentolamine. Anti-glycoprotein Ilia MoAb(SZ-21) inhibited HIP2-induced platelet aggregation, did not block HIP2 binding on platelet surface in IFS. HIP2 no affected platelet adhision on glass. HIP2 prolonged koalin cephalin clotting time in PRP and interruped whole blood retraction. Under electron microscopy, the fibrin formation of clots in the presence of HIP2 was much less than the control. Recently, we found that the platelets from patients with myelo-proligerative diseases had decreased response to HIP2 aggregation. So that, HIP2 MoAb may be a very useful tool not only for study of the platelet membrane structure associated with function of platelet and platelet physiology, but also of the pathogenesis of some platelet diseases.