Surface CD44 Research Articles

Chemotherapy-induced increase in CD47 expression in epithelial ovarian cancer.

Epithelial ovarian cancer (EOC) remains the most lethal gynecological malignancy with limited treatment options. CD47 is a critical immune checkpoint for tumor immune evasion and has been targeted in various clinical trials. This study aimed to assess the impact of chemotherapy on CD47 expression in EOC in order to determine the potential and optimal timing of CD47-targeted therapy in ovarian cancer. We analyzed the expression of CD47 in ovarian cancer and the effect of chemotherapy on the expression of CD47 in ovarian cancer tissues. Furthermore, we investigated the effect of chemotherapy on the expression of CD47 in ovarian cancer cells. CD47 expression was examined using immunohistochemistry (IHC) of specimens from 78 patients with EOC who underwent neoadjuvant chemotherapy (NACT) and interval debulking surgery (IDS) with paired tissue specimens obtained before and after NACT. A retrospective review of the medical records was conducted to correlate demographic and survival data. Subsequently, we employed reverse transcription quantitative polymerase chain reaction (RT-qPCR) and flow cytometry analysis to examine and compare CD47 expression across human ovarian surface epithelial cell line (HOSE), SKOV3, and ES2 cells and to characterize the changes in CD47 expression in SKOV3 and ES2 cells after cisplatin treatment. CD47 expression was observed in 63 out of 78 (80.8%) cases before NACT. The expression of CD47 was not associated with the clinicopathological characteristics or the prognosis of patients with EOC. After three cancer specimens were excluded due to the absence of cancer cells following NACT, Wilcoxon exact tests of 75 pairs of matched specimens indicated that the expression of CD47 increased after chemotherapy (P=0.006). CD47 was expressed at varying levels in HOSE ovarian epithelial cells and SKOV3 and ES2 ovarian cancer cells. Notably, the CD47 messenger RNA (mRNA) expression of HOSE cells was observed to be lower than that of the SKOV3 and ES2 ovarian cancer cells (P<0.001). Following treatment with cisplatin, RT-qPCR indicated an increase in CD47 mRNA expression in SKOV3 and ES2 cells (P<0.001). Flow cytometry revealed a notable elevation in the cell surface CD47 protein mean fluorescence intensity of cisplatin-treated SKOV3 and ES2 cells (P<0.001). CD47 is highly expressed in ovarian cancer, and NACT increases the expression of CD47, which may contribute to tumor immune evasion. It is possible that platinum-based chemotherapy may result in elevated CD47 mRNA expression and cell surface CD47 protein expression.

A CD38/CD3xCD28 trispecific T‐cell engager as a potentially active agent in multiple myeloma patients relapsed and/or refractory to anti‐CD38 monoclonal antibodies

SummaryThere is accumulating evidence of BCMA and GPRC5D loss after treatment with T‐cell redirecting therapies in patients with relapsed/refractory multiple myeloma (RRMM). While complete CD38 loss is not observed upon relapses after treatment with anti‐CD38 monoclonal antibodies (mAb), there is downregulation of surface CD38 expression and decreased number and function of NK cells, which renders these patients resistant to retreatment with anti‐CD38 mAb. Here, we provide preclinical evidence that RRMM patients previously exposed to anti‐CD38 mAb could benefit from T‐cell‐based immunotherapy that depend less on CD38 antigen density and NK‐cell activity, such as the novel CD38/CD3xCD28 trispecific T‐cell engager, SAR442257.

Targeting CD13/aminopeptidase N as a novel therapeutic approach for scleroderma fibrosis.

Systemic sclerosis (SSc) is an autoimmune multisystem disease with poorly understood pathogenesis and ineffective treatment options. Soluble CD13 (sCD13), generated by cleavage of cell surface CD13 via matrix metalloproteinase 14 (MMP14), signals through the bradykinin receptor B1 (B1R) to elicit pro-inflammatory, pro-arthritic, and pro-angiogenic responses. In this study we explored the anti-fibrotic potential of targeting the sCD13-B1R axis in SSc. The expression of CD13, B1R and MMP14 was examined in SSc skin and explanted dermal fibroblasts. The efficacy of B1R antagonists in the inhibition on fibrosis was determined in vitro and in vivo. Expression of the genes for CD13, B1R and MMP14 was elevated in skin biopsies from patients with diffuse cutaneous (dc)SSc. Notably, single cell analysis of SSc skin biopsies revealed the highest BDKRB1 expression in COL8A1-positive myofibroblasts, a population exclusively seen in SSc. TGF-β induced the expression of BDKRB1 and production of sCD13 by dcSSc skin fibroblasts. Treatment of dcSSc fibroblasts with sCD13 promoted fibrotic gene expression, signaling, cell proliferation, migration, and gel contraction. The profibrotic sCD13 or TGFβ responses were prevented by a B1R antagonist. Mice lacking Cd13 or Bdkrb1 were resistant to bleomycin-induced skin fibrosis and inflammation. Pharmacological B1R inhibition had a comparable antifibrotic effect. These results are the first to demonstrate a key role for sCD13 in SSc skin fibrosis, and suggest that targeting the sCD13-B1R signaling axis is a promising novel therapeutic approach for SSc.

Characterization of ibrutinib's effects on the morphology, proliferation, phenotype, viability, and anti-inflammatory potential of adipose-derived mesenchymal stromal cells

Ibrutinib (IB) is a tyrosine kinase inhibitor (TKI) that has immunomodulatory action and can be used as second-line therapy for steroid-refractory or steroid-resistant chronic Graft versus Host Disease (cGVHD). Mesenchymal stromal cells (MSCs) are distributed throughout the body and their infusion has also been explored as a second-line therapeutic alternative for the treatment of cGVHD. Considering the currently unknown effects of IB on endogenous MSCs, as well as the possible combined use of IB and MSCs for cGVHD, we investigated whether adipose tissue-derived MSCs present IB-targets, as well as the consequences of treating MSCs with this drug, regarding cell viability, proliferation, phenotype, and anti-inflammatory potential. Interestingly, we show for the first time that MSCs express several IB target genes. Also of note, the treatment of such cells with this TKI elevated the levels of CD90 and CD105 surface proteins, as well as VCAM-1. Furthermore, IB-treated MSCs presented increased mRNA expression of the anti-inflammatory genes PD-L1, TSG-6, and IL-10. However, continued exposure to IB, even at low doses, compromised the viability of MSCs. These data indicate that the use of IB can stimulate an anti-inflammatory profile in MSCs, but also that a continued exposure to IB can compromise MSC viability over time.

Endothelial Cell-Derived Soluble CD200 Determines the Ability of Immune Cells to Cross the Blood-Brain Barrier.

The infiltration of immune cells into the central nervous system mediates the development of autoimmune neuroinflammatory diseases. We previously showed that the loss of either Fabp5 or calnexin causes resistance to the induction of experimental autoimmune encephalomyelitis (EAE) in mice, an animal model of multiple sclerosis (MS). Here we show that brain endothelial cells lacking either Fabp5 or calnexin have an increased abundance of cell surface CD200 and soluble CD200 (sCD200) as well as decreased T-cell adhesion. In a tissue culture model of the blood-brain barrier, antagonizing the interaction of CD200 and sCD200 with T-cell CD200 receptor (CD200R1) via anti-CD200 blocking antibodies or the RNAi-mediated inhibition of CD200 production by endothelial cells increased T-cell adhesion and transmigration across monolayers of endothelial cells. Our findings demonstrate that sCD200 produced by brain endothelial cells regulates immune cell trafficking through the blood-brain barrier and is primarily responsible for preventing activated T-cells from entering the brain.

A novel anti-CD47 protein antibody and toll-like receptor agonist complex detects tumor surface CD-47 changes in early stage lung cancer by in vivo imaging

CD47, a cell surface protein known for inhibiting phagocytosis, plays a critical role in the tumor microenvironment (TME) and is a potential biomarker for cancer. However, directly applying αCD47, a hydrophilic macromolecular antibody that targets CD47, in vivo for cancer detection can have adverse effects on normal cells, cause systemic toxicities, and lead to resistance against anti-cancer therapies. In this study, we developed a novel complex incorporating aluminum-based metal-organic frameworks (Al-MOF) loaded with indocyanine green (ICG), αCD47, and resiquimod (R848), a hydrophobic small molecule Toll-like receptor 7/8 (TLR7/8) agonist. Upon activation with an infrared 808 nm laser, the nanocomposites exhibited photothermal effects that triggered the release of the loaded reagents, induced ROS production, and induced changes in the TME. This led to the polarization of immune-suppressive M2 macrophages towards an immune-stimulatory M1 phenotype, promoted dendritic cell (DC) maturation, and enabled mature DCs to facilitate antigen presentation, T-cell activation, and critical roles in tumor immunity. Furthermore, in vivo imaging successfully detected the specific binding of αCD47 with CD47 on tumor cells. Overall, the complex composed of αCD47 antibody and toll-like receptor agonist showed promising efficacy in both tumor diagnosis and therapy, providing a potential strategy for detecting early lung cancer and modulating the tumor microenvironment for improved treatment outcomes.

Fine-tuning spatial-temporal dynamics and surface receptor expression support plasma cell-intrinsic longevity

Durable serological memory following vaccination is critically dependent on the production and survival of long-lived plasma cells (LLPCs). Yet, the factors that control LLPC specification and survival remain poorly resolved. Using intravital two-photon imaging, we find that in contrast to most plasma cells (PCs) in the bone marrow (BM), LLPCs are uniquely sessile and organized into clusters that are dependent on APRIL, an important survival factor. Using deep, bulk RNA sequencing, and surface protein flow-based phenotyping, we find that LLPCs express a unique transcriptome and phenotype compared to bulk PCs, fine-tuning expression of key cell surface molecules, CD93, CD81, CXCR4, CD326, CD44, and CD48, important for adhesion and homing. Conditional deletion of Cxcr4 in PCs following immunization leads to rapid mobilization from the BM, reduced survival of antigen-specific PCs, and ultimately accelerated decay of antibody titer. In naïve mice, the endogenous LLPCs BCR repertoire exhibits reduced diversity, reduced somatic mutations, and increased public clones and IgM isotypes, particularly in young mice, suggesting LLPC specification is non-random. As mice age, the BM PC compartment becomes enriched in LLPCs, which may outcompete and limit entry of new PCs into the LLPC niche and pool.

Fine-tuning spatial-temporal dynamics and surface receptor expression support plasma cell-intrinsic longevity.

Durable serological memory following vaccination is critically dependent on the production and survival of long-lived plasma cells (LLPCs). Yet, the factors that control LLPC specification and survival remain poorly resolved. Using intravital two-photon imaging, we find that in contrast to most plasma cells (PCs) in the bone marrow (BM), LLPCs are uniquely sessile and organized into clusters that are dependent on APRIL, an important survival factor. Using deep, bulk RNA sequencing, and surface protein flow-based phenotyping, we find that LLPCs express a unique transcriptome and phenotype compared to bulk PCs, fine-tuning expression of key cell surface molecules, CD93, CD81, CXCR4, CD326, CD44, and CD48, important for adhesion and homing. Conditional deletion of Cxcr4 in PCs following immunization leads to rapid mobilization from the BM, reduced survival of antigen-specific PCs, and ultimately accelerated decay of antibody titer. In naïve mice, the endogenous LLPCs BCR repertoire exhibits reduced diversity, reduced somatic mutations, and increased public clones and IgM isotypes, particularly in young mice, suggesting LLPC specification is non-random. As mice age, the BM PC compartment becomes enriched in LLPCs, which may outcompete and limit entry of new PCs into the LLPC niche and pool.

Analysis of the TID-I and TID-L Splice Variants' Expression Profile under In Vitro Differentiation of Human Mesenchymal Bone Marrow Cells into Osteoblasts.

Bone formation is a complex process regulated by a variety of pathways that are not yet fully understood. One of the proteins involved in multiple osteogenic pathways is TID (DNAJA3). The aim of this work was to study the association of TID with osteogenesis. Therefore, the expression profiles of the TID splice variants (TID-L, TID-I) and their protein products were analyzed during the proliferation and differentiation of bone marrow mesenchymal stromal cells (B-MSCs) into osteoblasts. As the reference, the hFOB1.19 cell line was used. The phenotype of B-MSCs was confirmed by the presence of CD73, CD90, and CD105 surface antigens on ~97% of cells. The osteoblast phenotype was confirmed by increased alkaline phosphatase activity, calcium deposition, and expression of ALPL and SPP1. The effect of silencing the TID gene on the expression of ALPL and SPP1 was also investigated. The TID proteins and the expression of TID splice variants were detected. After differentiation, the expression of TID-L and TID-I increased 5-fold and 3.7-fold, respectively, while their silencing resulted in increased expression of SPP1. Three days after transfection, the expression of SPP1 increased 7.6-fold and 5.6-fold in B-MSCs and differentiating cells, respectively. Our preliminary study demonstrated that the expression of TID-L and TID-I changes under differentiation of B-MSCs into osteoblasts and may influence the expression of SPP1. However, for better understanding the functional association of these results with the relevant osteogenic pathways, further studies are needed.

Functional multiomics reveals genetic and pharmacologic regulation of surface CD38 in multiple myeloma

AbstractCD38 is a surface ectoenzyme expressed at high levels on myeloma plasma cells and is the target for the monoclonal antibodies (mAbs) daratumumab and isatuximab. Pretreatment CD38 density on tumor cells is an important determinant of mAb efficacy. Several small molecules have been found to increase tumor surface CD38, with the goal of boosting mAb efficacy in a cotreatment strategy. Numerous other CD38-targeting therapeutics are currently in preclinical or clinical development. Here, we sought to extend our currently limited insight into CD38 surface expression by using a multiomics approach. Genome-wide CRISPR interference screens integrated with patient–centered epigenetic analysis confirmed known regulators of CD38, such as RARA, while revealing XBP1 and SPI1 as other key transcription factors governing surface CD38 levels. CD38 knockdown followed by cell surface proteomics demonstrated no significant remodeling of the myeloma “surfaceome” after genetically induced loss of this antigen. Integrated transcriptome and surface proteome data confirmed high specificity of all-trans retinoic acid in upregulating CD38, in contrast to the broader effects of azacytidine and panobinostat. Finally, unbiased phosphoproteomics identified inhibition of MAP kinase pathway signaling in tumor cells after daratumumab treatment. Our work provides a resource to design strategies to enhance efficacy of CD38-targeting immunotherapies in myeloma.

Generation of iPSCs from a Patient with the M694V Mutation in the MEFV Gene Associated with Familial Mediterranean Fever and Their Differentiation into Macrophages.

Familial Mediterranean fever (FMF) is a systemic autoinflammatory disorder caused by inherited mutations in the MEFV (Mediterranean FeVer) gene, located on chromosome 16 (16p13.3) and encoding the pyrin protein. Despite the existing data on MEFV mutations, the exact mechanism of their effect on the development of the pathological processes leading to the spontaneous and recurrent autoinflammatory attacks observed in FMF, remains unclear. Induced pluripotent stem cells (iPSCs) are considered an important tool to study the molecular genetic mechanisms of various diseases due to their ability to differentiate into any cell type, including macrophages, which contribute to the development of FMF. In this study, we developed iPSCs from an Armenian patient with FMF carrying the M694V, p.(Met694Val) (c.2080A>G, rs61752717) pathogenic mutation in exon 10 of the MEFV gene. As a result of direct differentiation, macrophages expressing CD14 and CD45 surface markers were obtained. We found that the morphology of macrophages derived from iPSCs of a patient with the MEFV mutation significantly differed from that of macrophages derived from iPSCs of a healthy donor carrying the wild-type MEFV gene.

Human serum albumin-based drug-free macromolecular therapeutics induce apoptosis in chronic lymphocytic leukemia patient cells by crosslinking of CD20 and/or CD38 receptors.

This study explores the efficacy of human serum albumin (HSA)-based Drug-Free Macromolecular Therapeutics (DFMT) in treating Chronic Lymphocytic Leukemia (CLL), a prevalent adult leukemia subtype. DFMT, a novel strategy, employs biomimetic crosslinking of CD20 and CD38 receptors on malignant B cells without the need for low molecular weight drugs. Apoptosis is initiated via a two-step process: i) Recognition of a bispecific engager, Fab' fragment conjugated with morpholino oligonucleotide (Fab'-MORF1), by a cell surface antigen; followed by ii) crosslinking of the MORF1-decorated cells with a multivalent effector, HSA holding multiple copies of complementary MORF2, HSA-(MORF2)x. Herein we evaluated the efficacy of HSA-based DFMT in the treatment of 56 samples isolated from patients diagnosed with CLL. Fab' fragments from Obinutuzumab (OBN) and Isatuximab (ISA) were employed in the synthesis of anti-CD20 (Fab'OBN-MORF1) and anti-CD38 (Fab'ISA-MORF1) bispecific engagers. The efficacy of DFMT was significantly influenced by the expression levels of CD20 and CD38 receptors. Dual-targeting DFMT strategies (CD20 + CD38) were more effective than single-target approaches, particularly in samples with elevated receptor expression. Pretreatment of patient cells with gemcitabine or ricolinostat markedly increased cell surface CD20 and CD38 expression, respectively. Apoptosis was effectively initiated in 62.5% of CD20-targeted samples and in 42.9% of CD38-targeted samples. Our findings demonstrate DFMT's potential in personalized CLL therapy. Further research is needed to validate these outcomes in a larger number of patient samples and to explore DFMT's applicability to other malignancies.

Engineering Pancreatic Islets to Transiently Codisplay on Their Surface Thrombomodulin and CD47 Immunomodulatory Proteins as a Means of Mitigating Instant Blood-Mediated Inflammatory Reaction following Intraportal Transplantation.

Most pancreatic islets are destroyed immediately after intraportal transplantation by an instant blood-mediated inflammatory reaction (IBMIR) generated through activation of coagulation, complement, and proinflammatory pathways. Thus, effective mitigation of IBMIR may be contingent on the combined use of agents targeting these pathways for modulation. CD47 and thrombomodulin (TM) are two molecules with distinct functions in regulating coagulation and proinflammatory responses. We previously reported that the islet surface can be modified with biotin for transient display of novel forms of these two molecules chimeric with streptavidin (SA), that is, thrombomodulin chimeric with SA (SA-TM) and CD47 chimeric with SA (SA-CD47), as single agents with improved engraftment following intraportal transplantation. This study aimed to test whether islets can be coengineered with SA-TM and SA-CD47 molecules as a combinatorial approach to improve engraftment by inhibiting IBMIR. Mouse islets were effectively coengineered with both molecules without a detectable negative impact on their viability and metabolic function. Coengineered islets were refractory to destruction by IBMIR ex vivo and showed enhanced engraftment and sustained function in a marginal mass syngeneic intraportal transplantation model. Improved engraftment correlated with a reduction in intragraft innate immune infiltrates, particularly neutrophils and M1 macrophages. Moreover, transcripts for various intragraft procoagulatory and proinflammatory agents, including tissue factor, HMGB1 (high-mobility group box-1), IL-1β, IL-6, TNF-α, IFN-γ, and MIP-1α, were significantly reduced in coengineered islets. These data demonstrate that the transient codisplay of SA-TM and SA-CD47 proteins on the islet surface is a facile and effective platform to modulate procoagulatory and inflammatory responses with implications for both autologous and allogeneic islet transplantation.

Restoring NAD+ levels sensitize checkpoint resistant tumors to PD-1 therapy mediated through macrophage-NK-T cell crosstalk.

Abstract Immune checkpoint blockade therapy (ICB) often targets tumoricidal capacities of T cells. However, innate immune cells present in the tumor microenvironment (TME) play a decisive role in the efficacy of ICB. Therefore, developing combination therapies that target multiple immune populations is of considerable interest. Nicotinamide adenine dinucleotide (NAD+), the crucial metabolic intermediate, acts as a cofactor in redox processes and co-substrate for multiple enzymes. Immune populations in TME express surface CD38, a NAD hydrolase that reduces the tissue NAD+ levels, impairing T cells metabolic fitness. Here we used an antibody that blocks the NAD hydrolase activity of CD38 and is non-toxic in vivo, as compared to the commercially available anti-CD38 antibody (NIMR5), that relies upon antibody-dependent cellular cytotoxicity (ADCC). We found that combined therapy with αPD-1 and αCD38 antibody significantly enhances tumor control in PD-1-resistant melanoma model. Single-cell RNA sequencing, flowcytometry analysis and cell depletion studies revealed that combination therapy leads to transcriptional reprogramming of macrophages, improves macrophage-NK-T cell crosstalk, and facilitates immune infiltration in the TME. These results highlight the importance of boosting the TME's NAD+ level in conjunction with ICB and allude to the potential of an improved endogenous immune response against cancers that are resistant to checkpoint treatment and typically regarded as incurable.

Medicinal plant extracts interfere in gastric cancer stem cells fluorescence-based assays

Fluorescence is used in various biological assays due to its high sensitivity, versatility, and precision. In recent years, studies using medicinal plant extracts have increased. However, fluorescence-based assays could be biased by plant metabolites autofluorescence. To address this issue, this study investigated the interference caused by methanolic extracts and chloroform fractions of three medicinal plants in three fluorescence-based assays on gastric cancer stem cells(CSC): resazurin reduction, confocal microscopy, and flow cytometry. CSC were isolated based on CD44 surface marker, incubated with methanolic extracts and chloroform fractions of Buddleja incana, Dracontium spruceanum, Piper aduncum. Resazurin assay evidenced that CSC exposed to extracts and fractions from the three plants showed significant differences in relative fluorescence units (RFU) levels (p < 0.001) compared to the unexposed groups after a 3-hour incubation. In addition, DMSO-treated CSC exposed to extracts and fractions had significantly lower fluorescence levels than living ones, but higher than extracts and fractions without cells. In confocal microscopy, cancer stem cells exposed to extracts and fractions of B. incana and P. aduncum were observed in the same emission spectra of the CSC markers. In flow cytometry, CSC exposed to extracts and fractions without any fluorescent dyes were detected in the double positive quadrants for CSC markers (CD44+/CD133 + ). Among the three plants, D. spruceanum exhibited the least interference. These results show that methanolic extracts and chloroform fractions contain autofluorescent metabolites that interfere with fluorescence-based assays. These results highlight the importance of a prior evaluation for possible fluorescence interference to avoid interpretation biases in fluorescence assays.

Extracellular Vesicles Isolated from Equine Adipose-Derived Stromal Stem Cells (ASCs) Mitigate Tunicamycin-Induced ER Stress in Equine Corneal Stromal Stem Cells (CSSCs).

Corneal ulcers, characterized by severe inflammation of the cornea, can lead to serious, debilitating complications and may be vision-threatening for horses. In this study, we aimed to investigate the role of endoplasmic reticulum (ER) stress in corneal stem progenitor cell (CSSC) dysfunction and explore the potential of equine adipose-derived stromal stem cell (ASC)-derived extracellular vesicles (EVs) to improve corneal wound healing. We showed that CSSCs expressed high levels of CD44, CD45, and CD90 surface markers, indicating their stemness. Supplementation of the ER-stress-inducer tunicamycin to CSSCs resulted in reduced proliferative and migratory potential, accumulation of endoplasmic reticulum (ER)-stressed cells in the G0/G1 phase of the cell cycle, increased expression of proinflammatory genes, induced oxidative stress and sustained ER stress, and unfolded protein response (UPR). Importantly, treatment with EVs increased the proliferative activity and number of cells in the G2/Mitosis phase, enhanced migratory ability, suppressed the overexpression of proinflammatory cytokines, and upregulated the anti-inflammatory miRNA-146a-5p, compared to control and/or ER-stressed cells. Additionally, EVs lowered the expression of ER-stress master regulators and effectors (PERK, IRE1, ATF6, and XBP1), increased the number of mitochondria, and reduced the expression of Fis-1 and Parkin, thereby promoting metabolic homeostasis and protecting against apoptosis in equine CSSCs. Our findings demonstrate that MSCs-derived EVs represent an innovative and promising therapeutic strategy for the transfer of bioactive mediators which regulate various cellular and molecular signaling pathways.

Abstract LB131: CBO421, a novel drug Fc-conjugate, inhibits the enzymatic activity of CD73 and triggers CD73 internalization

Abstract Background: CD73 (5’-nucleotidase or NT5E) is a cell surface enzyme responsible for the rate limiting step in adenosine production; the conversion of adenosine monophosphate (AMP) into adenosine. Immunosupressive adenosine contributes to immune evasion in solid tumors by accumulating within the tumor microenvironment and thereby inhibiting immune effector cells (e.g., CD8+ T cells). CD73 expression levels correlate with a worse prognosis in specific cancer types, including breast cancer. Adenosine production via CD73 can be therapeutically inhibited by two independent mechanisms: (1) enzyme inhibition, and (2) receptor internalization and subsequent degradation. CBO421, a drug Fc-conjugate (DFC), comprised of a novel small molecule CD73 inhibitor stably conjugated to an immune-silent human IgG1 Fc, achieves both mechanisms, combining the strengths of small molecule inhibitors and CD73-targeting monoclonal antibodies (mAbs) with potential best-in-class efficacy. Methods: The activities of CBO421, a commercially sourced CD73 small molecule inhibitor, quemliclustat (AB680), and biosimilar anti-CD73 mAb, oleclumab (MEDI9447), were investigated. Enzymatic inhibition of soluble CD73 and membrane-bound CD73 on MDA-MB-231 cells was determined. Receptor-mediated internalization of CD73 was assessed using the human triple-negative breast cancer cell line (TNBC), MDA-MB-231, by flow cytometry. Cells were treated with CBO421 or oleclumab. CD73 internalization was measured as the decrease in CD73 surface receptor signal over a 6 h time-course using an anti-human CD73 detection antibody with non-overlapping epitopes to CBO421 or oleclumab. Results: CD73 inhibition by CBO421 of soluble CD73 or CD73 expressed on the surface of the MDA-MB-231 cell line was comparable or superior to AB680 or oleclumab. Receptor internalization activities of CBO421 and oleclumab were compared. CBO421 and oleclumab internalization percentages were determined at 1 h (52.3% vs 26.7%), 4 h (80.8% vs 38.0%), and 6 h (84.8% vs 42.9%) respectively, with CBO421 demonstrating superior maximal receptor internalization. The unconjugated hIgG1 Fc negative control did not exhibit any receptor-mediated internalization of CD73, as expected. IC50 values were also calculated for CBO421 and oleclumab at 1 h (0.20 nM vs 0.88 nM), 4 h (0.07 nM vs 0.27 nM), and 6 h (0.08 nM vs 0.14 nM), respectively. Conclusions: CBO421 demonstrated potent and complete CD73 enzyme inhibition and robust CD73 receptor internalization in CD73+ cancer cells that was superior to oleclumab, thereby further differentiating CBO421 from existing CD73-targeting therapeutics currently in clinical development. Based on these compelling results and additional emerging data, CBO421 is progressing as a potential best-in-class clinical development candidate for the treatment of solid cancers. Citation Format: Elizabeth Abelovski, Nicholas Dedeic, Simon Döhrmann, James Levin, Amanda Almaguer, Doug Zuill, Joanne Fortier, Qiping Zhao, Maria Hernandez, Karin Amundson, Madison Moniz, Hongyuan Chen, Dhanya Panickar, Thanh Lam, Tom Brady, Allen Borchardt, Grayson Hough, Jeffrey B. Locke, Jason N. Cole, Leslie W. Tari. CBO421, a novel drug Fc-conjugate, inhibits the enzymatic activity of CD73 and triggers CD73 internalization [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB131.

Abstract 1906: UNO-A001 (A001), a clinical candidate CD38 x CD3 bispecific with a novel structure, potently kills multiple myeloma cells in vitro and is highly effective in vivo

Abstract CD38 is a validated target for the treatment of multiple myeloma (MM) as evidenced by the important clinical activity of CD38 targeting monoclonal antibodies. Bispecific T Cell Engagers (TCEs) kill cancer cells by distinct mechanisms as compared to standard format antibody therapeutics and several TCEs have demonstrated impressive clinical activity, and have been approved for clinical use, in hematologic malignancies. Here we describe a novel bispecific leveraging the potent killing mechanism of TCEs to target CD38 bearing cancer cells. UNO-A001 is a TCE binding the cell surface receptor CD38 on target human cancer cells and CD3 on T cells. The molecule has a differentiated format, binding CD38 with a high affinity humanized camelid VHH moiety and CD3 on T cells through a unique antibody Fab arm. The affinities of each arm were optimized so that the CD38 arm bound with high affinity and the CD3 arm with much lower relative binding affinity. This configuration was designed to engage CD38 bearing target cells with multiple TCE molecules at lower doses and concentrations while minimizing T cell binding in the periphery, and in the absence of cell surface CD38. A001 potently and specifically killed human CD38 bearing multiple myeloma cell lines in T cell killing assays in vitro with EC50s in the 2.7-6.6 pM range. This potency, despite the designed lower affinity to CD3, may be due to the unique structure of A001 enabling a productive immunologic synapse between T cells and the target cancer cells, and an optimal TAA/CD3 binding affinity ratio. A001 was also highly effective in inhibiting tumor growth in H929 xenograft models. In a flank model of H929 tumor growth A001 dose dependently inhibited tumor growth with complete growth inhibition of established tumors at the highest dose level tested. In a systemic disease model with NCI-H929-luc cells A001 was also highly effective and improved survival relative to control treated animals. In preparation for clinical studies a robust and high yield production cell line was created and characterized. It achieved high expression levels of quality monodisperse UNO-A001 product that was stable in all relevant storage conditions. A001 has similar affinities for human and cynomolgus macaque CD38 and CD3. Dose ranging studies in cynomolgus macaques demonstrated tolerability consistent with clinically approved TCEs, and the expected dose dependent pharmacodynamic effects on CD38 expressing myeloid and lymphoid cell populations. These data support planned clinical testing of A001 in multiple myeloma and other CD38 bearing hematologic malignancies, including mantle cell lymphoma, T cell lymphoma, and acute myelogenous leukemia. Citation Format: Mark Anderson, Yan Ling, Mark L. Chiu, Peter Cheung. UNO-A001 (A001), a clinical candidate CD38 x CD3 bispecific with a novel structure, potently kills multiple myeloma cells in vitro and is highly effective in vivo [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1906.

Assessment of the feasibility of human amniotic membrane stem cell-derived cardiomyocytes in vitro

Myocardial infarction (MI) is a leading cause of death worldwide, resulting in extensive loss of cardiomyocytes and subsequent heart failure. Inducing cardiac differentiation of stem cells is a potential approach for myocardial regeneration therapy to improve post-MI prognosis. Mesenchymal stem cells (MSCs) have several advantages, including immune privilege and multipotent differentiation potential. This study aimed to explore the feasibility of chemically inducing human amniotic membrane MSCs (hAMSCs) to differentiate into cardiomyocytes in vitro. Human amniotic membrane (AM) samples were obtained from routine cesarean sections at Far Eastern Memorial Hospital. The isolated cells exhibited spindle-shaped morphology and expressed surface antigens CD73, CD90, CD105, and CD44, while lacking expression of CD19, CD11b, CD19, CD45, and HLA-DR. The SSEA-1, SSEA-3, and SSEA-4 markers were also positive, and the cells displayed the ability for tri-lineage differentiation into adipocytes, chondrocytes, and osteoblasts. The expression levels of MLC2v, Nkx2.5, and MyoD were analyzed using qPCR after applying various protocols for chemical induction, including BMP4, ActivinA, 5-azacytidine, CHIR99021, and IWP2 on hAMSCs. The group treated with 5 ng/ml BMP4, 10 ng/ml Activin A, 10 μM 5-azacytidine, 7.5 μM CHIR99021, and 5 μM IWP 2 expressed the highest levels of these genes. Furthermore, immunofluorescence staining demonstrated the expression of α-actinin and Troponin T in this group. In conclusion, this study demonstrated that hAMSCs can be chemically induced to differentiate into cardiomyocyte-like cells in vitro. However, to improve the functionality of the differentiated cells, further investigation of inductive protocols and regimens is needed.

Abstract A014: Role of stromal CD10 expression in progression of endometrial and endometriosis-associated cancers

Abstract Endometriosis-associated carcinomas (EACs) and endometrial malignancies have many commonalities yet their pathophysiology, particularly those with high-risk histology such as clear cell, is understudied. EACs are histologically and clinically distinct from other gynecological cancers due to their unique origin within endometriosis. The endometriotic microenvironment is uniquely hypoxic with high levels of iron due to recurrent menstrual cycling, and this iron-rich microenvironment has been linked to promoting carcinogenesis through iron-induced oxidative stress. However, the mechanism by which the endometriotic microenvironment contributes to EAC tumorigenesis and how this compares with endometrial cancer is unknown. Most of our current knowledge of EACs is built on either epidemiologic analyses or correlative studies. Additionally, most studies of the endometriotic microenvironment primarily focus on the epithelial component while the role of the stroma has been largely unexplored. Mesenchymal stem cells (MSC) are a critical component of the stromal microenvironment. Recently, we identified a key role of endometriosis derived MSCs (enMSCs) in altering ovarian clear cell carcinoma iron regulation. Interestingly, enMSCs resemble the primary endometrium derived MSCs, which suggested their role in endometrial cancer. This stromal subset is characterized by the loss of surface CD10 expression. It is known that cancer cells, particularly clear cell carcinoma (CCC), have a unique requirement for high levels of iron. We hypothesize that CD10 negative enMSCs promote growth of EAC and endometrial cancer through iron regulation. MSCs were isolated from primary human benign endometriosis, benign endometrium, or endometrial cancer. Flow cytometry was used to measure surface CD10 expression. We investigated the role of CD10 negative enMSCs on CCC iron regulation. Our results showed that CD10 negative enMSCs promote CCC growth by exporting iron through the upregulation of Hephaestin (HEPH) and Ferroportin (FPO) which then led to increase labile iron pool (LIP) in CCC cells. However, increasing the LIP does not occur with iron supplementation alone, this indicates the critical role of CD10 negative enMSCs in regulating iron handling in CCC cells. Additionally, our data showed that CD10 negative enMSCs alter the balance of Ferritin L and Ferritin H- the main iron storage proteins- in CCC cells. Mechanistically, our preliminary data showed that CD10 negative enMSCs directly donate Ferritin L into CCC cells. Further, CD10 negative enMSCs enhance Ferritin H degradation through the upregulation of ferritinophagy in CCC cells. In conclusion, our results indicate there is a sub-population of enMSCs, marked by the loss of CD10 expression, that enhances EAC and endometrial cancer cell growth through iron regulation. This highlights the existence of a tumor-promoting stromal cell within both the endometrium and endometriosis which can be capitalized on as an “Achilles' heel” to uncover novel treatment targets for EAC and endometrial cancer. Citation Format: Huda I. Atiya, Lan G. Coffman. Role of stromal CD10 expression in progression of endometrial and endometriosis-associated cancers [abstract]. In: Proceedings of the AACR Special Conference on Endometrial Cancer: Transforming Care through Science; 2023 Nov 16-18; Boston, Massachusetts. Philadelphia (PA): AACR; Clin Cancer Res 2024;30(5_Suppl):Abstract nr A014.