B7-H3-Targeting Chimeric Antigen Receptors Epstein-Barr Virus-specific T Cells Provides a Tumor Agnostic Off-The-Shelf Therapy Against B7-H3-positive Solid Tumors.

Encouraged by the observations of significant B7-H3 protein overexpression in many human solid tumors compared to healthy tissues, we directed our focus towards targeting B7-H3 using chimeric antigen receptor (CAR) T cells. We utilized a nanobody as the B7-H3-targeting domain in our CAR construct to circumvent the stability issues associated with single-chain variable fragment-based domains. In efforts to expand patient access to CAR T-cell therapy, we engineered our nanobody-based CAR into human Epstein-Barr virus-specific T cells (EBVST), offering a readily available off-the-shelf treatment. B7H3.CAR-armored EBVSTs demonstrated potent in vitro and in vivo activities against multiple B7-H3-positive human tumor cell lines and patient-derived xenograft models. Murine T cells expressing a murine equivalent of our B7H3.CAR exhibited no life-threatening toxicities in immunocompetent mice bearing syngeneic tumors. Further in vitro evaluation revealed that while human T, B, and natural killer cells were unaffected by B7H3.CAR EBVSTs, monocytes were targeted because of upregulation of B7-H3. Such targeting of myeloid cells, which are key mediators of cytokine release syndrome (CRS), contributed to a low incidence of CRS in humanized mice after B7H3.CAR EBVST treatment. Notably, we showed that B7H3.CAR EBVSTs can target B7-H3-expressing myeloid-derived suppressor cells (MDSC), thereby mitigating MDSC-driven immune suppression. In summary, our data demonstrate that our nanobody-based B7H3.CAR EBVSTs are effective as an off-the-shelf therapy for B7-H3-positive solid tumors. These cells also offer an avenue to modulate the immunosuppressive tumor microenvironment, highlighting their promising clinical potential in targeting solid tumors. Clinical application of EBVSTs armored with B7-H3-targeting CARs offer an attractive solution to translate off-the-shelf CAR T cells as therapy for solid tumors.

Yeo SP ，Kua L ，Tan JW ，Lim JK ，Wong FH ，Santos MD ，Poh CM ，Goh AX ，Koh XY ，Zhou X ，Rajarethinam R ，Chen Q ，Her Z ，Horak ID ，Low L ，Tan KW ... -  《-》

B7-H3-Targeted CAR-Vδ1T Cells Exhibit Potent Broad-Spectrum Activity Against Solid Tumors.

Jiang L ，You F ，Wu H ，Qi C ，Xiang S ，Zhang P ，Meng H ，Wang M ，Huang J ，Li Y ，Chen D ，An G ，Yang N ，Zhang B ，Shen L ，Yang L ... -  《-》

Engineered oncolytic virus expressing B7H3-targeting BiTE enhances antitumor T-cell immune response.

Bispecific T-cell engagers (BiTEs) are recombinant bispecific proteins designed to stimulate polyclonal T-cell immunity. In recent years, B7H3, a pan-cancer antigen, has been considered a promising target for future immunotherapy. However, the B7H3-targeting BiTE faces the challenge of systemic toxicity. Oncolytic viruses (OVs) represent a new class of cancer immunotherapeutics and serve as an appropriate platform for locoregional delivery of therapeutic genes. In this study, we designed an oncolytic adenovirus (OAd) encoding BiTE targeting human B7H3. We hypothesized that OVs encoding B7H3 BiTE deliver this molecule persistently to the tumor site while mediating polyclonal T-cell activation and redirecting it to tumor cells. B7H3-targeting BiTE was constructed by linking a single-chain variable fragment (scFv) that recognizes human B7H3 to an scFv that recognizes human CD3. B7H3 BiTE was inserted into OAd to construct OAd-B7H3-BiTE. The function of the OV-delivered B7H3 BiTE was detected via co-culturing B7H3+ target cells and peripheral blood mononuclear cells. A humanized immune system mouse model was used to evaluate the therapeutic effects in vivo. B7H3 is highly expressed in a high proportion of human malignancies. OV-delivered BiTEs bind to T cells and target cells. We observed a series of phenomena reflecting T-cell activation induced by OAd-B7H3-BiTE, including cell clustering, cell size, activation markers, cytokine secretion, and proliferation. Furthermore, T-cell activation was mirrored by the corresponding cytotoxicity against B7H3+ tumor cells. In vivo, B7H3 BiTE was persistently expressed in tumors and enhanced the antitumor T-cell immune response. Using an OV for the local expression of B7H3 BiTE maximizes the local concentration of BiTE while reducing systemic exposure. OV also provides a relatively "hot" T-cell immune environment for the function of BiTE. Because of its capacity to activate polyclonal T cells, BiTE has the potential to redirect virus-specific T cells to tumors. Our study provides new opportunities for the exploitation of B7H3-BiTE-armed OVs as therapeutic agents for the treatment of B7H3-positive malignancies.

Zhu H ，Zhang W ，Guo Q ，Fan R ，Luo G ，Liu Y ... -  《Journal for ImmunoTherapy of Cancer》

STRIvE-02: A First-in-Human Phase I Study of Systemically Administered B7-H3 Chimeric Antigen Receptor T Cells for Patients With Relapsed/Refractory Solid Tumors.

Pinto N ，Albert CM ，Taylor MR ，Ullom HB ，Wilson AL ，Huang W ，Wendler J ，Pattabhi S ，Seidel K ，Brown C ，Gustafson JA ，Rawlings-Rhea SD ，Cheeney SHE ，Burleigh K ，Gustafson HH ，Orentas RJ ，Vitanza NA ，Gardner RA ，Jensen MC ，Park JR ... -  《-》

Tumor-derived G-CSF induces an immunosuppressive microenvironment in an osteosarcoma model, reducing response to CAR.GD2 T-cells.

Sarcomas are rare, mesenchymal tumors, representing about 10-15% of all childhood cancers. GD2 is a suitable target for chimeric antigen receptor (CAR) T-cell therapy due to its overexpression in several solid tumors. In this preclinical study, we investigated the potential use of iCasp9.2A.GD2.CAR-CD28.4-1BBζ (CAR.GD2) T-cells as a treatment option for patients who have GD2-positive sarcomas and we sought to identify factors shaping hostile tumor microenvironment in this setting. GD2 expression was evaluated by flow-cytometry on primary tumor biopsies of pediatric sarcoma patients. GD2 expression in sarcoma cells was also evaluated in response to an enhancer of zeste homolog 2 (EZH2) inhibitor (Tazemetostat). The antitumor activity of CAR.GD2 T-cells was evaluated both in vitro and in vivo preclinical models of orthotopic and/or metastatic soft-tissue and bone sarcomas. GD2 expression was detected in 55% of the primary tumors. Notably, the Osteosarcoma and Alveolar Rhabdomyosarcomas subtypes exhibited the highest GD2 expression levels, while Ewing sarcoma showed the lowest. CAR.GD2 T-cells show a significant tumor control both in vitro and in vivo models of GD2-expressing tumors. Pretreatment with an EZH2 inhibitor (Tazemetostat) upregulating GD2 expression, sensitizes GD2dim sarcoma cells to CAR.GD2 T-cells cytotoxic activity. Moreover, in mouse models of disseminated Rhabdomyosarcomas and orthotopic Osteosarcoma, CAR.GD2 T-cells showed both a vigorous anti-tumor activity and long-term persistence as compared to un-transduced T-cells. The presence of immunosuppressive murine myeloid-derived suppressor (MDSC) cells significantly reduces long-term anti-tumour activity of infused CAR.GD2 T-cells. Tumor-derived G-CSF was found to be one of the key factors driving expansion of immunosuppressive murine and human MDSC, thus indirectly limiting the efficacy of CAR.GD2 T-cells. Our preclinical data strongly suggest that CAR.GD2 T-cells hold promise as a potential therapeutic option for the treatment of patients with GD2-positive sarcomas. Strategies to tackle hostile immunosuppressive MDSC are desirable to optimize CAR.GD2 T-cell activity.

Pezzella M ，Quintarelli C ，Quadraccia MC ，Sarcinelli A ，Manni S ，Iaffaldano L ，Ottaviani A ，Ciccone R ，Camera A ，D'Amore ML ，Di Cecca S ，Sinibaldi M ，Guercio M ，Aurigemma M ，De Falco P ，Fustaino V ，Rota R ，Pomella S ，Cassandri M ，Di Giannatale A ，Agrati C ，Bordoni V ，Guarracino F ，Massa M ，Del Baldo G ，Becilli M ，Milano GM ，Del Bufalo F ，Locatelli F ，De Angelis B ... -  《Journal of Hematology & Oncology》