Developing ROR1 Targeting CAR-T Cells against Solid Tumors in Preclinical Studies

Targeting endothelial cell anergy to improve CAR T cell therapy for solid tumors

Chimeric antigen receptor (CAR) T cell therapy presents significant results, especially for the treatment of hematologic malignancies. However, there are limitations and challenges to be overcome to achieve similar success for the treatment of solid tumors. These challenges involve selection of the target, infiltration into the tumor microenvironment and maintenance of functionality. The tumor vasculature is a major barrier for leukocytes to enter the tumor parenchyma. Due to the exposure of the vasculature to angiogenic growth factors during tumor progression, the endothelial cells become anergic to inflammatory cytokines, resulting in reduced leukocyte adhesion molecule expression. As such adhesion molecules are a prerequisite for leukocyte extravasation, endothelial cell anergy allows tumors to escape from endogenous immunity, as well as from cellular immunotherapies such as CAR T cells. Hence, overcoming endothelial cell anergy, e.g. through the administration of angiogenesis inhibitors, is believed to restore anti-tumor immunity. Concomitantly, both endogenous immune cells as well as cellular therapeutics such as CAR T cells can permeate into the tumor parenchyma. Here, we discuss how prior or concomitant treatment with an antiangiogenic drug can improve CAR T cell therapy, to become an attractive strategy for the treatment of solid tumors.

Development of Peptide Paratope Mimics Derived from the Anti-ROR1 Antibody and Long-Acting Peptide-Drug Conjugates for Targeted Cancer Therapy

Antibody-based targeted therapy in cancer faces a challenge due to uneven antibody distribution in solid tumors, hindering effective drug delivery. We addressed this by developing peptide mimetics with nanomolar-range affinity for Receptor Tyrosine Kinase-Like Orphan Receptor 1 (ROR1) using computational methods. These peptides showed both specific targeting and deep penetration in vitro and in vivo. Additionally, we created peptide-drug conjugates (PDCs) by linking targeting peptides to toxin drugs via various linkers and enhancing their in vivo half-life with fatty side chains for albumin binding. The antitumor candidate II-3 displayed exceptional affinity (KD = 1.72 × 10-9 M), internalization efficiency, anticancer potency (IC50 = 0.015 ± 0.002 μM), and pharmacokinetics (t1/2 = 2.6 h), showcasing a rational approach for designing PDCs with favorable tissue distribution and strong tumor penetration.

Receptor tyrosine kinase-like orphan receptor serves as a potential target in cancer immunotherapy

Receptor tyrosine kinase-like orphan receptor (ROR), consisting of ROR1 and ROR2, is a conserved family of receptor tyrosine kinase superfamily that plays crucial roles during embryonic development with limited expression in adult normal tissues. However, it is overexpressed in a range of hematological malignancies and solid tumors and functions in cellular processes including cell survival, polarity, and migration, serving as a potential target in cancer immunotherapy. This review summarizes the expression and structure of ROR in developmental morphogenesis and its function in cancers associated with Wnt5a signaling and highlights the cancer immunotherapy strategies targeting ROR.

Dihydroartemisinin inhibits tumor progress via blocking ROR1-induced STAT3-activation in non-small cell lung cancer

In non-small cell lung cancer (NSCLC), identifying a component with certain molecular targets can aid research on cancer treatment. Dihydroartemisinin (DHA) is a semisynthetic derivative of artemisinin which induced the anti-cancer effects via the STAT3 signaling pathway, but the underlying molecular mechanism is still elusive. In this study, we first proved that DHA prohibits the growth of tumors both in vitro and in vivo. Data from transcriptomics showed that DHA reduced the expression level of the genes involved in cell cycle-promoting and anti-apoptosis, and most importantly, DHA restricted the expression level of receptor tyrosine kinase-like orphan receptor 1 (ROR1) which has been reported to have abnormal expression on tumor cells and had close interaction with STAT3 signaling. Then, we performed comprehensive experiments and found that DHA remarkably decreased the expression of ROR1 at both mRNA and protein levels and it also diminished the phosphorylation level of STAT3 in NSCLC cell lines. In addition, our data showed that exogenously introduced ROR1 could significantly enhance the phosphorylation of STAT3 while blocking ROR1 had the opposite effects indicating that ROR1 plays a critical role in promoting the activity of STAT3 signaling. Finally, we found that ROR1 overexpression could partially reverse the decreased activity of STAT3 induced by DHA which indicates that DHA-induced anti-growth signaling is conferred, at least in part, through blocking ROR1-mediated STAT3 activation. In summary, our study indicates that in NSCLC, ROR1 could be one of the critical molecular targets mediating DHA-induced STAT3 retardation.

Receptor tyrosine kinase-like orphan receptor 1: A novel antitumor target in gastrointestinal cancers

Receptor tyrosine kinase-like orphan receptor 1 (ROR1) is a member of the type I receptor tyrosine kinase family. ROR1 is pivotal in embryonic development and cancer, and serves as a biomarker and therapeutic target. It has soluble and membrane-bound subtypes, with the latter highly expressed in tumors. ROR1 is conserved throughout evolution and may play a role in the development of gastrointestinal cancer through multiple signaling pathways and molecular mechanisms. Studies suggest that overexpression of ROR1 may increase tumor invasiveness and metastasis. Additionally, ROR1 may regulate the cell cycle, stem cell characteristics, and interact with other signaling pathways to affect cancer progression. This review explores the structure, expression and role of ROR1 in the development of gastrointestinal cancers. It discusses current antitumor strategies, outlining challenges and prospects for treatment.

Advancing CAR T-cell therapy for chronic lymphocytic leukemia: exploring resistance mechanisms and the innovative strategies to overcome them

Chimeric antigen receptor (CAR) T-cell therapy has ushered in substantial advancements in the management of various B-cell malignancies. However, its integration into chronic lymphocytic leukemia (CLL) treatment has been challenging, attributed largely to the development of very effective chemo-free alternatives. Additionally, CAR T-cell responses in CLL have not been as high as in other B-cell lymphomas or leukemias. However, a critical void exists in therapeutic options for patients with high-risk diseases who are resistant to the current CLL therapies, underscoring the urgency for adoptive immunotherapies in these patients. The diminished CAR T-cell efficacy within CLL can be traced to factors such as compromised T-cell fitness due to persistent antigenic stimulation inherent to CLL. Resistance mechanisms encompass tumor-related factors like antigen escape, CAR T-cell-intrinsic factors like T-cell exhaustion, and a suppressive tumor microenvironment (TME). New strategies to combat CAR T-cell resistance include the concurrent administration of therapies that augment CAR T-cell endurance and function, as well as the engineering of novel CAR T-cells targeting different antigens. Moreover, the concept of "armored" CAR T-cells, armed with transgenic modulators to modify both CAR T-cell function and the tumor milieu, is gaining traction. Beyond this, the development of readily available, allogeneic CAR T-cells and natural killer (NK) cells presents a promising countermeasure to innate T-cell defects in CLL patients. In this review, we explore the role of CAR T-cell therapy in CLL, the intricate tapestry of resistance mechanisms, and the pioneering methods studied to overcome resistance.

Novel and multiple targets for chimeric antigen receptor-based therapies in lymphoma

Chimeric antigen receptor (CAR) T-cell therapy targeting CD19 in B-cell non-Hodgkin lymphoma (NHL) validates the utility of CAR-based therapy for lymphomatous malignancies. Despite the success, treatment failure due to CD19 antigen loss, mutation, or down-regulation remains the main obstacle to cure. On-target, off-tumor effect of CD19-CAR T leads to side effects such as prolonged B-cell aplasia, limiting the application of therapy in indolent diseases such as chronic lymphocytic leukemia (CLL). Alternative CAR targets and multi-specific CAR are potential solutions to improving cellular therapy outcomes in B-NHL. For Hodgkin lymphoma and T-cell lymphoma, several cell surface antigens have been studied as CAR targets, some of which already showed promising results in clinical trials. Some antigens are expressed by different lymphomas and could be used for designing tumor-agnostic CAR. Here, we reviewed the antigens that have been studied for novel CAR-based therapies, as well as CARs designed to target two or more antigens in the treatment of lymphoma.

Transforming CLL management with immunotherapy: Investigating the potential of CAR T-cells and bispecific antibodies

Immunotherapies, such as chimeric antigen receptor (CAR) T-cell therapy and bispecific antibodies or T-cell engagers, have revolutionized the treatment landscape for various B-cell malignancies, including B-acute lymphoblastic leukemia and many non-Hodgkin lymphomas. Despite their significant impact on these malignancies, their application in chronic lymphocytic leukemia (CLL) management is still largely under investigation. Although the initial success of CD19-directed CAR T-cell therapy was observed in 3 multiply relapsed CLL patients, with 2 of them surviving over 10 years without relapse, recent CAR T-cell therapy trials in CLL have shown reduced response rates compared to their efficacy in other B-cell malignancies. One of the challenges with using immunotherapy in CLL is the compromised T-cell fitness from persistent CLL-related antigenic stimulation, and an immunosuppressive tumor microenvironment (TME). These challenges underscore a critical gap in therapeutic options for CLL patients intolerant or resistant to current therapies, emphasizing the imperative role of effective immunotherapy. Encouragingly, innovative strategies are emerging to overcome these challenges. These include integrating synergistic agents like ibrutinib to enhance CAR T-cell function and persistence and engineering newer CAR T-cell constructs targeting diverse antigens or employing dual-targeting approaches. Bispecific antibodies are an exciting "off-the-shelf" prospect for these patients, with their investigation in CLL currently entering the realm of clinical trials. Additionally, the development of allogeneic CAR T-cells and natural killer (NK) cells from healthy donors presents a promising solution to address the diminished T-cell fitness observed in CLL patients. This comprehensive review delves into the latest insights regarding the role of immunotherapy in CLL, the complex landscape of resistance mechanisms, and a spectrum of innovative approaches to surmount therapeutic challenges.

Current status and future challenges of CAR-T cell therapy for osteosarcoma

Osteosarcoma, the most common bone malignancy in children and adolescents, poses considerable challenges in terms of prognosis, especially for patients with metastatic or recurrent disease. While surgical intervention and adjuvant chemotherapy have improved survival rates, limitations such as impractical tumor removal or chemotherapy resistance hinder the treatment outcomes. Chimeric antigen receptor (CAR)-T cell therapy, an innovative immunotherapy approach that involves targeting tumor antigens and releasing immune factors, has shown significant advancements in the treatment of hematological malignancies. However, its application in solid tumors, including osteosarcoma, is constrained by factors such as low antigen specificity, limited persistence, and the complex tumor microenvironment. Research on osteosarcoma is ongoing, and some targets have shown promising results in pre-clinical studies. This review summarizes the current status of research on CAR-T cell therapy for osteosarcoma by compiling recent literature. It also proposes future research directions to enhance the treatment of osteosarcoma.

Anti-ROR1 CAR-T cells: Architecture and performance

The receptor tyrosine kinase-like orphan receptor 1 (ROR1) is a membrane receptor that plays a key role in development. It is highly expressed during the embryonic stage and relatively low in some normal adult tissues. Malignancies such as leukemia, lymphoma, and some solid tumors overexpress ROR1, making it a promising target for cancer treatment. Moreover, immunotherapy with autologous T-cells engineered to express a ROR1-specific chimeric antigen receptor (ROR1 CAR-T cells) has emerged as a personalized therapeutic option for patients with tumor recurrence after conventional treatments. However, tumor cell heterogeneity and tumor microenvironment (TME) hinder successful clinical outcomes. This review briefly describes the biological functions of ROR1 and its relevance as a tumor therapeutic target, as well as the architecture, activity, evaluation, and safety of some ROR1 CAR-T cells used in basic research and clinical trials. Finally, the feasibility of applying the ROR1 CAR-T cell strategy in combination with therapies targeting other tumor antigens or with inhibitors that prevent tumor antigenic escape is also discussed.

Clinical trial registration

https://clinicaltrials.gov/, identifier NCT02706392.