Colony-stimulating Factor 1 Receptor Research Articles

Targeting CSF1R in myeloid-derived suppressor cells: insights into its immunomodulatory functions in colorectal cancer and therapeutic implications

ObjectiveThis study aimed to investigate the critical role of MDSCs in CRC immune suppression, focusing on the CSF1R and JAK/STAT3 signaling axis. Additionally, it assessed the therapeutic efficacy of LNCs@CSF1R siRNA and anti-PD-1 in combination.MethodsSingle-cell transcriptome sequencing data from CRC and adjacent normal tissues identified MDSC-related differentially expressed genes. RNA-seq analysis comprehensively profiled MDSC gene expression in murine CRC tumors. LNCs@CSF1R siRNA nanocarriers effectively targeted and inhibited CSF1R. Flow cytometry quantified changes in MDSC surface markers post-CSF1R inhibition. RNA-seq and pathway enrichment analyses revealed the impact of CSF1R on MDSC metabolism and signaling. The effect of CSF1R inhibition on the JAK/STAT3 signaling axis was validated using Colivelin and metabolic assessments. Glucose and fatty acid uptake were measured via fluorescence-based flow cytometry. The efficacy of LNCs@CSF1R siRNA and anti-PD-1, alone and in combination, was evaluated in a murine CRC model with extensive tumor section analyses.ResultsCSF1R played a significant role in MDSC-mediated immune suppression. LNCs@CSF1R siRNA nanocarriers effectively targeted MDSCs and inhibited CSF1R. CSF1R regulated MDSC fatty acid metabolism and immune suppression through the JAK/STAT3 signaling axis. Inhibition of CSF1R reduced STAT3 activation and target gene expression, which was rescued by Colivelin. Combined treatment with LNCs@CSF1R siRNA and anti-PD-1 significantly slowed tumor growth and reduced MDSC abundance within CRC tumors.ConclusionCSF1R via the JAK/STAT3 axis critically regulates MDSCs, particularly in fatty acid metabolism and immune suppression. Combined therapy with LNCs@CSF1R siRNA and anti-PD-1 enhances therapeutic efficacy in a murine CRC model, providing a strong foundation for future clinical applications.

Reflective imaging of myelin integrity in the human and mouse central nervous systems.

The structural integrity of myelin sheaths in the central nervous system (CNS) is crucial for the maintenance of its function. Electron microscopy (EM) is the gold standard for visualizing individual myelin sheaths. However, the tissue processing involved can induce artifacts such as shearing of myelin, which can be difficult to distinguish from true myelin abnormalities. Spectral confocal reflectance (SCoRe) microscopy is an imaging technique that leverages the differential refractive indices of compacted CNS myelin in comparison to surrounding parenchyma to detect individual compact myelin internodes with reflected light, positioning SCoRe as a possible complementary method to EM to assess myelin integrity. Whether SCoRe is sensitive enough to detect losses in myelin compaction when myelin quantity is otherwise unaffected has not yet been directly tested. Here, we assess the capacity of SCoRe to detect differences in myelin compaction in two mouse models that exhibit a loss of myelin compaction without demyelination: microglia-deficient mice (Csf1r-FIRE Δ/Δ) and wild-type mice fed with the CSF1R inhibitor PLX5622. In addition, we compare the ability to detect compact myelin sheaths using SCoRe in fixed-frozen versus paraffin-embedded mouse tissue. Finally, we show that SCoRe can successfully detect individual sheaths in aged human paraffin-embedded samples of deep white matter regions. As such, we find SCoRe to be an attractive technique to investigate myelin integrity, with sufficient sensitivity to detect myelin ultrastructural abnormalities and the ability to perform equally well in tissue preserved using different methods.

L-Wnk1 Deletion in Smooth Muscle Cells Causes Aortitis and Inflammatory Shift.

The long isoform of the Wnk1 (with-no-lysine [K] kinase 1) is a ubiquitous serine/threonine kinase, but its role in vascular smooth muscle cells (VSMCs) pathophysiology remains unknown. AngII (angiotensin II) was infused in Apoe-/- to induce experimental aortic aneurysm. Mice carrying an Sm22-Cre allele were cross-bred with mice carrying a floxed Wnk1 allele to specifically investigate the functional role of Wnk1 in VSMCs. Single-cell RNA-sequencing of the aneurysmal abdominal aorta from AngII-infused Apoe-/- mice revealed that VSMCs that did not express Wnk1 showed lower expression of contractile phenotype markers and increased inflammatory activity. Interestingly, WNK1 gene expression in VSMCs was decreased in human abdominal aortic aneurysm. Wnk1-deficient VSMCs lost their contractile function and exhibited a proinflammatory phenotype, characterized by the production of matrix metalloproteases, as well as cytokines and chemokines, which contributed to local accumulation of inflammatory macrophages, Ly6Chi monocytes, and γδ T cells. Sm22Cre+Wnk1lox/lox mice spontaneously developed aortitis in the infrarenal abdominal aorta, which extended to the thoracic area over time without any negative effect on long-term survival. AngII infusion in Sm22Cre+Wnk1lox/lox mice aggravated the aortic disease, with the formation of lethal abdominal aortic aneurysms. Pharmacological blockade of γδ T-cell recruitment using neutralizing anti-CXCL9 (anti-CXC motif chemokine ligand 9) antibody treatment, or of monocyte/macrophage using Ki20227, a selective inhibitor of CSF1 receptor, attenuated aortitis. Wnk1 deletion in VSMCs led to aortic wall remodeling with destruction of elastin layers, increased collagen content, and enhanced local TGF-β (transforming growth factor-beta) 1 expression. Finally, in vivo TGF-β blockade using neutralizing anti-TGF-β antibody promoted saccular aneurysm formation and aorta rupture in Sm22 Cre+ Wnk1lox/lox mice but not in control animals. Wnk1 is a key regulator of VSMC function. Wnk1 deletion promotes VSMC phenotype switch toward a pathogenic proinflammatory phenotype, orchestrating deleterious vascular remodeling and spontaneous severe aortitis in mice.

Redefining the ontogeny of hyalocytes as yolk sac-derived tissue-resident macrophages of the vitreous body

BackgroundThe eye is a highly specialized sensory organ which encompasses the retina as a part of the central nervous system, but also non-neural compartments such as the transparent vitreous body ensuring stability of the eye globe and a clear optical axis. Hyalocytes are the tissue-resident macrophages of the vitreous body and are considered to play pivotal roles in health and diseases of the vitreoretinal interface, such as proliferative vitreoretinopathy or diabetic retinopathy. However, in contrast to other ocular macrophages, their embryonic origin as well as the extent to which these myeloid cells might be replenished by circulating monocytes remains elusive.ResultsIn this study, we combine transgenic reporter mice, embryonic and adult fate mapping approaches as well as parabiosis experiments with multicolor immunofluorescence labeling and confocal laser-scanning microscopy to comprehensively characterize the murine hyalocyte population throughout development and in adulthood. We found that murine hyalocytes express numerous well-known myeloid cell markers, but concomitantly display a distinct immunophenotype that sets them apart from retinal microglia. Embryonic pulse labeling revealed a yolk sac-derived origin of murine hyalocytes, whose precursors seed the developing eye prenatally. Finally, postnatal labeling and parabiosis established the longevity of hyalocytes which rely on Colony Stimulating Factor 1 Receptor (CSF1R) signaling for their maintenance, independent of blood-derived monocytes.ConclusionOur study identifies hyalocytes as long-living progeny of the yolk sac hematopoiesis and highlights their role as integral members of the innate immune system of the eye. As a consequence of their longevity, immunosenescence processes may culminate in hyalocyte dysfunction, thereby contributing to the development of vitreoretinal diseases. Therefore, myeloid cell-targeted therapies that convey their effects through the modification of hyalocyte properties may represent an interesting approach to alleviate the burden imposed by diseases of the vitreoretinal interface.

Evaluation of a Positron Emission Tomography Tracer Targeting Colony-Stimulating Factor 1 Receptor for Detecting Pulmonary Inflammation.

Colony-stimulating factor 1 receptor (CSF1R) is a type III receptor tyrosine kinase that is crucial for immune cell activation, survival, proliferation, and differentiation. Its expression significantly increases in macrophages during inflammation, playing a crucial role in regulating inflammation resolution and termination. Consequently, CSF1R has emerged as a critical target for both therapeutic intervention and imaging of inflammatory diseases. Herein, we have developed a radiotracer, 1-[4-((7-(dimethylamino)quinazolin-4-yl)oxy)phenyl]-3-(4-[18F]fluorophenyl)urea ([18F]17), for in vivo positron emission tomography (PET) imaging of CSF1R. Compound 17 exhibits a comparable inhibitory potency against CSF1R as the well-known CSF1R inhibitor PLX647. The radiosynthesis of [18F]17 was successfully performed by radiofluorination of aryltrimethyltin precursor with a yield of approximately 12% at the end of synthesis, maintaining a purity exceeding 98%. In vivo stability and biodistribution studies demonstrate that [18F]17 remains >90% intact at 30 min postinjection, with no defluorination observed even at 60 min postinjection. The PET/CT imaging study in lipopolysaccharide-induced pulmonary inflammation mice indicates that [18F]17 offers a more sensitive characterization of pulmonary inflammation compared to traditional [18F]FDG. Notably, [18F]17 shows a higher discrepancy in uptake ratio between mice with pulmonary inflammation and the sham group. Furthermore, the variations in [18F]17 uptake ratio observed on day 7 and day 14 correspond to lung density changes observed in CT imaging. Moreover, the expression levels of CSF1R on day 7 and day 14 follow a trend similar to the uptake pattern of [18F]17, indicating its potential for accurately characterizing CSF1R expression levels and effectively monitoring the pulmonary inflammation progression. These results strongly suggest that [18F]17 has promising prospects as a CSF1R PET tracer, providing diagnostic opportunities for pulmonary inflammatory diseases.

Microglial repopulation induced by PLX3397 protects against ischemic brain injury by suppressing neuroinflammation in aged mice

As the resident immune cells in the central nervous system, microglia exhibit a ‘sensitized’ or ‘primed’ phenotype with dystrophic morphology and dysregulated functions in aged brains. Although studies have demonstrated the inflammatory profile of aged microglia in several neurological diseases, this issue is largely uncertain in stroke. Consequently, this study investigated the effects of primed and repopulated microglia on post-ischemic brain injury in aged mice. We replaced primed microglia with newly repopulated microglia through pharmacological administration and withdrawal of the colony-stimulating factor 1 receptor (CSF1R) inhibitor, PLX3397. Further, we performed a series of behavioral tests and flow cytometry in mouse models of middle cerebral artery occlusion (MCAO) to study the effects of microglial replacement on ischemic injury in the aged brain. With depletion and subsequent repopulation of microglia in MCAO mice, microglial replacement in aged mice improved neurological function and decreased brain infarction. This protective effect was accompanied by the reduction of peripheral immune cells infiltrating into brains. We showed that the repopulated microglia expressed elevated neuroprotective factors (including Cluster of Differentiation 206, transforming growth factor-β, and interleukin-10) and diminished expression of inflammatory markers (including Cluster of Differentiation 86, interleukin-6, and tumor necrosis factor α). Moreover, microglial replacement protected the blood–brain barrier and relieved neuronal death in aged mice subjected to 60 min of MCAO. These results imply that the replacement of microglia in the aged brain may alleviate brain damage and neuroinflammation, and therefore, ischemic brain damage. Thus, targeting microglia could be a promising therapeutic strategy for ischemic stroke.

IL-34 and its receptors as predictors of brain metastasis and prognosis in lung adenocarcinoma: Unveiling insights through bioinformatic and immunohistochemical investigations

BackgroundBrain metastasis (BM) is a prevalent form of metastasis in lung adenocarcinoma (LUAD), necessitating investigations into the underlying mechanisms. Interleukin 34 (IL-34) and its receptors, macrophage colony-stimulating factor-1 receptor (CSF-IR), Syndecan-1 (SDC-1), and protein-tyrosine phosphatase zeta receptor (PTPRZ1), are known to play pivotal roles in the metastasis of malignant tumors, thereby holding promise as potential biomarkers for studying BM in LUAD. MethodsWe performed immunohistochemistry to analyze the expression of IL-34, CSF-1R, SDC-1, and PTPRZ1 in 10 pairs of LUAD primary tissues and BMs, along with 96 unpaired primary tissues and 68 unpaired BMs. Subsequently, we evaluated the association between protein expression and the occurrence of BM. Furthermore, Kaplan-Meier survival curve analysis was conducted on both network and clinical data to explore the association between protein expression and patient prognosis and survival. ResultsAt the protein level, the expression of IL-34 and its receptors showed significant variation between paired primary tumors and BMs in 10 LUAD patients. The levels of IL-34, CSF-1R, and SDC-1 expression are typically elevated in brain metastatic lesions of LUAD compared to primary LUAD tumors. Furthermore, patients with high CSF-1R expression in primary LUAD are at a greater risk of developing brain metastases. High expression of IL-34 and CSF-1R in primary LUAD lesions indicated poor disease-free survival (DFS) and overall survival (OS), while high expression of SDC-1 indicated poor OS. Cox multivariate analysis further revealed that CSF-1R and IL-34+CSF-1R positivity independently affected LUAD OS. These findings were further substantiated in unpaired samples. ConclusionsOur results indicate significant alterations in the expression of IL-34 and its receptors, CSF-1R and SDC-1, between LUAD primary lesions and BMs, with increased expression observed in BMs. LUAD patients with positive CSF-1R expression in primary lesions exhibited a higher likelihood of developing BM, and high expression of IL-34, CSF-1R, and SDC-1 correlated with poor prognosis. These findings contribute novel insights towards identifying potential treatment or diagnostic targets for metastatic LUAD.

Pexidartinib and Immune Checkpoint Inhibitors Combine to Activate Tumor Immunity in a Murine Colorectal Cancer Model by Depleting M2 Macrophages Differentiated by Cancer-Associated Fibroblasts.

Tumor-associated macrophages (TAMs) and cancer-associated fibroblasts (CAFs) are known to play supportive roles in tumor development and progression, but their interactions in colorectal cancer (CRC) remain unclear. Here, we investigated the effects of colon-cancer-derived CAFs on TAM differentiation, migration, and tumor immunity, both in vitro and in vivo. When co-cultured with monocytes, CAFs attracted monocytes and induced their differentiation into M2 macrophages. Immunohistology of surgically resected human CRC specimens and orthotopically transplanted mouse tumors revealed a correlation between numbers of CAFs and numbers of M2 macrophages. In a mouse model of CRC orthotopic transplantation, treatment with an inhibitor of the colony-stimulating factor-1 receptor (PLX3397) depleted M2 macrophages and increased CD8-positive T cells infiltrating the tumor nest. While this treatment had a minor effect on tumor growth, combining PLX3397 with anti-PD-1 antibody significantly reduced tumor growth. RNA-seq following combination therapy showed activation of tumor immunity. In summary, CAFs are involved in the induction and mobilization of M2 macrophage differentiation in the CRC tumor immune microenvironment, and the combination of cancer immunotherapy and PLX3397 may represent a novel therapeutic option for CRC.

Hypoxia inducible factor 2α promotes tolerogenic macrophage development during cardiac transplantation through transcriptional regulation of colony stimulating factor 1 receptor

Solid organ transplantation mobilizes myeloid cells, including monocytes and macrophages, which are central protagonists of allograft rejection. However, myeloid cells can also be functionally reprogrammed by perioperative costimulatory blockade to promote a state of transplantation tolerance. Transplantation tolerance holds promise to reduce complications from chronic immunosuppression and promote long-term survival in transplant recipients. We sought to identify different mediators of transplantation tolerance by performing single-cell RNA sequencing of acute rejecting or tolerized cardiac allografts. This led to the unbiased identification of the transcription factor, hypoxia inducible factor (HIF)-2α, in a subset of tolerogenic monocytes. Using flow cytometric analyses and mice with conditional loss or gain of function, we uncovered that myeloid cell expression of HIF-2α was required for costimulatory blockade-induced transplantation tolerance. While HIF-2α was dispensable for mobilization of tolerogenic monocytes, which were sourced in part from the spleen, it promoted the expression of colony stimulating factor 1 receptor (CSF1R). CSF1R mediates monocyte differentiation into tolerogenic macrophages and was found to be a direct transcriptional target of HIF-2α in splenic monocytes. Administration of the HIF stabilizer, roxadustat, within micelles to target myeloid cells, increased HIF-2α in splenic monocytes, which was associated with increased CSF1R expression and enhanced cardiac allograft survival. These data support further exploration of HIF-2α activation in myeloid cells as a therapeutic strategy for transplantation tolerance.

ETMR-12. INFANTILE CENTRAL NERVOUS SYSTEM JUVENILE XANTHOGRANULOMA WITH SOMATICCSF1R MUTATION - RESPONSIVE TO IMATINIB MONOTHERAPY

Abstract BACKGROUND Juvenile xanthogranuloma (JXG) of the central nervous system(CNS) is a rare non-Langerhans cell histiocytosis typically affecting children and young adults. CSF1R mutations have been reported for peripheral JXG but have not previously been reported in CNS JXG. Treatment of CNS JXG relies on maximal safe surgical resection followed by cytotoxic chemotherapy, radiotherapy and/or molecular targeted therapy involving MAPK signaling pathway. Imatinib has been effective in treating tenosynovial giant cell tumor with CSF1R mutations. METHODS Case Report RESULTS A 3 month old male presented with fever, lymphadenopathy, and macrocephaly (45.5cm, 99.97%) with bulging fontanelles. Head ultrasound revealed dilated ventricles and brain MRI demonstrated multiple dural-based masses, the largest measuring 6.6 x 5.3 x 5.7 cm was located along the right tentorium and caused obstructive hydrocephalus. Patient underwent right frontal endoscopic third ventriculostomy and choroid plexus cauterization to treat hydrocephalus and right parietal craniotomy to resect the superficial dural-based mass for tissue diagnosis. Pathology was most consistent with a JXG that harbored a somatic CSF1R (NM_001288705.3) mutation. DNA Methylation profiling was unmatched. PET scan was negative for non-CNS lesions. Due to the multiple masses on presentation, the surgical risks of resection of the largest lesion, as well as having a targetable mutation, we opted for medical therapy. As Pexidartinib, a selective CSF1R inhibitor, was not available for infants, patient was started on liquid imatinib 340 mg/m2/day monotherapy. Three months after initiation of imatinib, the smaller parietal lesions resolved and after six months, the largest mass continued to shrink (6.3 x 2.9 x 2.9 cm). Treatment has been well tolerated without adverse events or drug interruptions. CONCLUSION This is the first report of CNS JXG with a CSF1R mutation. Importantly, it demonstrates that imatinib is a potentially safe and effective form of monotherapy for this rare disease.

IMMU-06. CAR DESIGN SHAPES THE BRAIN TUMOR IMMUNE MICROENVIRONMENT: IMPACT ON ACTIVITY AND PERSISTENCE OF ANTI-GLIOMA ADOPTIVE T CELL IMMUNOTHERAPY

Abstract BACKGROUND B7-H3 CAR T-cells effectively eradicate brain tumors in xenograft models and have proven safe in clinical trials, yet no objective responses were observed in patients. The limited efficacy is partly attributed to the immunosuppressive tumor microenvironment (TME), a characteristic not fully recapitulated in investigations using xenograft models. In this study, we set to optimize B7-H3 CAR structure and examine the effects of CAR design on the brain TME using an immunocompetent glioma model. METHODS We generated a panel of fully murine B7-H3 CARs with variations in transmembrane, co-stimulatory, and activation domains. This enabled us to comprehensively investigate their effector functions within the intact immune system. High-dimensional flow cytometry and single-cell RNA sequencing were then used to investigate changes in the brain TME following CAR T-cell therapy. RESULTS While five out of six B7-H3 CARs with single co-stimulatory domains exhibited potent functionality in vitro, optimizing co-stimulation and signaling failed to enhance their anti-glioma efficacy in vivo. To further enhance therapeutic effectiveness and persistence, we incorporated 4-1BB and CD28 co-stimulation through transgenic expression of 4-1BBL on CD28-based CAR T-cells. Although this design significantly improved anti-glioma efficacy in vitro, it conferred no additional benefits in vivo. Analysis of the TME revealed that CAR T-cell therapy influenced the immune composition of the brain TME. Successful anti-tumor responses were dictated by the recruitment, activation, and spatial localization of unique inflammatory ‘immune hubs’ containing specific subsets of macrophages and endogenous T-cells. Interestingly, depletion of brain macrophages using CSF1R inhibitor markedly inhibited CAR T-cell anti-tumor activity. CONCLUSION Our study highlights the critical role of CAR structural design and its modulation of the TME in mediating the efficacy of CAR T-cell therapy in brain tumors. Yet, more specific targeting and/or reprogramming of the TME is warranted for the successful design of effective adoptive immunotherapies for high-grade glioma.

Characterization of CD83 homologs differently expressed during monocytes differentiation in ginbuna crucian carp, Carassius auratus langsdorfii.

CD83 is a costimulatory molecule of antigen-presenting cells (APCs) that plays an important role in eliciting adaptive responses. It is also a well-known surface protein on mature dendritic cells (DCs). Furthermore, monocytes have been reported to differentiate into macrophages and monocyte-derived dendritic cells, which play an important role in innate immunity. CD83 expression affects the activation and maturation of DCs and stimulates cell-mediated immune responses. This study aims to reveal the CD83 expression during monocyte differentiation in teleosts, and the CD83 homologs evolutionary relationship. This study found two distinct CD83 homologs (GbCD83 and GbCD83-L) in ginbuna crucian carp (Gb) and investigated the evolutionary relationship among GbCD83 homologs and other vertebrates and the gene and protein expression levels of the homologs during 4 days of monocyte culture. The phylogenetic tree showed that the two GbCD83 homologs are classified into two distinct branches. Interestingly, only ostariophysians (Gb, common carp, rohu, fathead minnow and channel catfish), but not neoteleosts, mammals, and others, have two CD83 homologs. Morphological observation and colony-stimulating factor-1 receptor (CSF-1R), CD83, CD80/86, and CCR7 gene expressions illustrated that there is a differentiation of monocytes isolated from peripheral blood leukocytes after 4 days. Specifically, gene expression and immunocytochemistry revealed that GbCD83 is mainly expressed on monocytes at the early stage of cell culture, whereas GbCD83-L is expressed in the latter stage. These findings provided the first evidence of differential expression of CD83 homologs during monocytes differentiation in teleost.

Identification and characterization of a novel intronic splicing mutation in CSF1R-related leukoencephalopathy.

Colony stimulating factor 1 receptor (CSF1R)-related leukoencephalopathy is a rapidly progressing neurodegenerative disease caused by CSF1R gene mutations. This study aimed to identify and investigate the effect of a novel intronic mutation (c.1754-3C>G) of CSF1R on splicing. A novel intronic mutation was identified using whole-exome sequencing. To investigate the impact of this mutation, we employed various bioinformatics tools to analyze the transcription of the CSF1R gene and the three-dimensional structure of its encoded protein. Furthermore, reverse transcription polymerase chain reaction (RT-PCR) was performed to validate the findings. A novel mutation (c.1754-3C>G) in CSF1R was identified, which results in exon 13 skipping due to the disruption of the 3' splice site consensus sequence NYAG/G. This exon skipping event was further validated in the peripheral blood of the mutation carrier through RT-PCR and Sanger sequencing. Protein structure prediction indicated a disruption in the tyrosine kinase domain, with the truncated protein showing significant structural alterations. Our findings underscore the importance of intronic mis-splicing mutations in the diagnosis and management of CSF1R-related leukoencephalopathy.

A novel CSF1R missense mutation in a Chinese family with adult-onset leukoencephalopathy with axonal spheroids and pigmented glia: A case report

Adult-onset leukoencephalopathy with axonal spheroids and pigmented glia (ALSP) is a rare autosomal dominant disorder caused by mutations in the colony-stimulating factor 1 receptor (CSF1R) gene. We report a case of a 41-year-old man with rapid decline in cognition within 7 months of onset. Magnetic resonance imaging showed periventricular confluent white matter changes and atrophy of the corpus callosum. Clinical exome sequencing showed a mutation (c.2390T>G) in exon 18 of the CSF1R gene. In conclusion, the differential diagnosis of adult-onset leukodystrophy is extensive. Neuroimaging and genetic analysis greatly aid in the differential diagnosis of leukoencephalopathy.

A phase I clinical trial investigating the safety, tolerability, and pharmacokinetics of HX301 (narazaciclib), a novel multi-kinase inhibitor targeting CSF1R, CDK 4/6, and ARK5, in patients with advanced solid tumors.

e15106 Background: HX301 (narazaciclib) is a promising novel multi-kinase inhibitor with potent activity against Colony Stimulating Factor 1 Receptor (CSF1R), Cyclin-Dependent Kinase 4/6 (CDK4/6), and Aurora Kinase 5 (ARK5), with a half-maximal inhibitory concentration (IC50) values in 0.29-4.95 nM range. It is an oral bioavailable agent and has the ability to cross blood-brain barrier. Preclinical data have showed significant antitumor activities, warranting further clinical trials to evaluate the safety, and potential efficacy in human subjects. Methods: Utilizing the standard 3+3 design, the study aimed to evaluate the safety, tolerability and pharmacokinetics of ascending doses of HX301. Patients with heavily pretreated advanced solid tumors received HX301single agent via oral administration, with doses ranging from 40mg to 200mg once daily for the first 21 days of each 28-day cycle. Results: As of December 27, 2023, a total of 20 patients (5 males, 15 females) were enrolled in the study, with varying doses of HX301 administered: 40 mg (n=3), 80 mg (n=3), 120 mg (n=4), 160 mg (n=3), and 200 mg (n=7). The median age of the patients was 55 years, ranging from 30 to 71. Notably, 15 patients (75%) had metastatic breast cancers. Dose-limiting toxicities (DLTs) were observed in 2 patients in the 200 mg group. These included a Grade 4 increase in alanine aminotransferase (ALT) and a Grade 3 decrease in platelet counts with associated epistaxis, both of which resolved after discontinuation of treatment. The most common treatment-related adverse events (AEs) observed were elevated aspartate aminotransferase (AST) (65.0%), decreased white blood cell count (50%), decreased neutrophil count (50%), elevated ALT (45%), elevated creatine kinase (45%), and elevated creatinine (35%). Additionally, 4 patients experienced Grade 3 or higher treatment-related AEs, including 1 patient in the 160 mg group with Grade 3 elevated γ-glutamyl transferase and alkaline phosphatase, and 3 patients in the 200 mg group with Grade 4 elevated ALT and Grade 3 elevated AST and Dyspepsia, Grade 3 decreased neutrophil and platelet counts, and Grade 3 hyperglycemia. Notably, no AEs led to death. Among the 20 patients evaluable for tumor assessment using RECIST 1.1 by Investigators, 4 obtained stable disease, including 2 patients in the 200 mg group, 1 in the 120 mg group, and 1 in the 80 mg group. Furthermore, 1 patient with HR+ breast cancer in the 200 mg group received study drug for over a year and achieved prolonged stable disease for more than 12 months, highlighting a notable clinical outcome. Conclusions: HX301 at dose levels ranging from 40mg to 160mg was tolerable with a manageable toxicity profile. Further clinical studies are needed to explore the drug's anti-tumor activity, particularly in combination settings. Clinical trial information: NCT05731934 .

Efficacy, safety, and patient-reported outcomes of vimseltinib in patients with tenosynovial giant cell tumor: Results from the phase 3 MOTION trial.

11500 Background: Tenosynovial giant cell tumor (TGCT) is a locally aggressive neoplasm caused by dysregulation of the colony-stimulating factor 1 ( CSF1) gene leading to overproduction of CSF1. TGCT requires a therapy with low toxicity as patients (pts) may need long-term treatment; there is an unmet need for an effective, well-tolerated CSF1 receptor (CSF1R)-targeted therapy that improves functional health and quality of life (QoL). Vimseltinib is an investigational, oral, switch-control tyrosine kinase inhibitor specifically designed to selectively and potently inhibit CSF1R. Here we report results from the MOTION trial. Methods: MOTION is a global, phase 3, double-blind study of vimseltinib in pts with symptomatic TGCT not amenable to surgery (NCT05059262). Randomization was 2:1 to vimseltinib 30 mg twice weekly or matching placebo (pbo) for 24 weeks. The primary endpoint was objective response rate (ORR) assessed by blinded independent radiological review (IRR) per Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST v1.1) at week 25. Key secondary endpoints assessed at week 25 were ORR by IRR per tumor volume score (TVS), change from baseline in active range of motion (ROM) of the affected joint and patient-reported outcomes (PROs; PRO Measurement Information System physical function score [PROMIS-PF], worst stiffness numeric rating scale, and EuroQol Visual Analog Scale [EQ-VAS]), and brief pain inventory worst pain response. Safety was also evaluated. Data cutoff was August 22, 2023. Results: Overall, 123 pts were randomized to vimseltinib (n = 83) or pbo (n = 40). Median age was 44 years, 59% of pts were female, and the most common primary disease location was the knee (67%). ORR at week 25 by IRR per RECIST v1.1 and per TVS were significantly higher for vimseltinib vs pbo (RECIST: 40% vs 0%, P < 0.0001; TVS: 67% vs 0%; P < 0.0001). Significant improvements from baseline to week 25 were observed with vimseltinib vs pbo in active ROM (18.4% vs 3.8%; P = 0.0077), physical function (PROMIS-PF: 3.3-point difference between arms, P = 0.0007), worst stiffness (−1.8-point difference, P < 0.0001), and health status (EQ-VAS: 7.4-point difference, P = 0.0155). There were also significantly more pain responders treated with vimseltinib (48% vs 23%; P = 0.0056). Most non-laboratory treatment-emergent adverse events were grade 1/2, and there was no evidence of cholestatic hepatotoxicity or drug-induced liver injury. Conclusions: Patients treated with vimseltinib experienced statistically significant and clinically meaningful improvements in ORR by RECIST v1.1 and by TVS, active ROM, physical function, stiffness, health status, and pain vs pbo. Vimseltinib is an effective, well-tolerated CSF1R-targeted therapy that demonstrates significant clinical benefit and improves functional health and QoL in pts with symptomatic TGCT not amenable to surgery. Clinical trial information: NCT05059262 .

Efficacy and safety of surufatinib combined with EP regimen and serplulimab in first-line treatment of NEC.

e15123 Background: Neuroendocrine carcinomas (NEC) are more challenging than neuroendocrine tumors (NET) due to poor differentiation, aggressive invasion, and early diagnosis difficulties, often marked by local and distant metastasis at diagnosis, leading to poor outcomes. The ORR for NEC as first-line treatment with EP or EC regimens is approximately 30%, highlighting a substantial treatment gap. Surufatinib, a targeted small molecule kinase inhibitor, acts on vascular endothelial growth factor receptors (VEGFR-1/2/3), fibroblast growth factor receptor (FGFR-1), and colony-stimulating factor-1 receptor (CSF-1R). Its efficacy focuses on anti-angiogenesis and vascular normalization, alongside its role in modulating tumor-associated macrophages (TAMs) and boosting the effectiveness of immunotherapy. Methods: This single-arm, open-label, multicenter clinical study comprised a safety run-in (SR) phase and a dose-expansion (DE) phase. In the SR phase, six patients (pts) were planned to be enrolled to receive treatment with surufatinib (250 mg, QD, PO, Q3W) combined with the EP regimen (etoposide injection: 100mg/m2, d1-3, IV, Q3W; cisplatin: 25mg/m2, d1-3, IV, Q3W) and serplulimab (300mg, d1, IV, Q3W) for a maximum of six cycles, followed by a maintenance phase of surufatinib plus serplulimab until disease progression or other criteria as specified in the protocol. The dose of surufatinib in the DE phase was based on results from the SR phase. The primary endpoints were recommended Phase 2 dose (RP2D) and PFS, while secondary endpoints included ORR, DCR, OS, and safety. Results: As of December 27, 2023, this reports results from the SR phase. Six pts, median age 61.5 years (range 38-70), 66.7% male, all with ECOG performance status 1, were enrolled and completed their first treatment cycle. A majority (83.3%) had gastrointestinal-origin tumors with a median Ki-67% index of 70% (range 30%-90%). During the SR phase, one patient experienced Grade 4 hematologic toxicity (neutropenia and leukopenia) as a dose-limiting toxicity (DLT). Consequently, RP2D of surufatinib was established at 250mg for further research in the DE phase. The most common adverse events were neutropenia (50%), decreased white blood cell count (33.3%), fatigue (33.3%), and diarrhea (33.3%). Among those enrolled in the SR phase, 5 pts underwent at least one assessment of efficacy, yielding an objective response rate (ORR) of 60% and a disease control rate (DCR) of 100%, with the median progression-free survival (mPFS) not yet mature. Conclusions: Surufatinib combined with the EP regimen and serplulimab for NEC as first-line treatment showed notable efficacy and safety. The study established a phase II recommended surufatinib dose of 250mg, alongside immunotherapy and chemotherapy. Clinical trial information: NCT05747729 .

Efficacy and safety of second-line treatment with surufatinib for anlotinib-resistant radioiodine-refractory differentiated thyroid cancer: An exploratory multicenter study.

e15127 Background: Radioiodine-refractory differentiated thyroid cancer (RR-DTC) resistant to first-line targeted therapy typically exhibits rapidly progressive nature, lacking standard treatment options. This study aimed to assess the efficacy and safety of surufatinib, targeting vascular endothelial growth factor receptor 1/2/3, fibroblast growth factor receptor 1, and colony-stimulating factor-1 receptor, in RR-DTC patients who had failed anlotinib treatment. Methods: This multicenter study enrolled patients aged ≥ 18 years with at least one measurable RR-DTC lesion (RECIST 1.1), who had previously received anlotinib treatment and experienced disease progression. Primary endpoint was progression-free survival (PFS); secondary endpoints were disease control rate and safety. Results: As of December 25, 2023, 9 patients were enrolled. Median age, 56 (range, 29-69) years; Male, 88.9%; ECOG PS 0, 88.9%; papillary carcinoma/follicular carcinoma, 77.8%/22.2%. Lung (77.8%) and bone (33.3%) were the most frequently involved organs. The duration of anlotinib treatment ≤ 12 months was found in 44.4% patients. All the 9 patients underwent at least one efficacy evaluation with a median PFS of 6.3 months and disease control rate of 88.9%. Subsequent analysis revealed that median PFS extended to 9.20 months in patients younger than 56 years, compared to 5.95 months in older individuals. Patients with over 12 months of prior anlotinib treatment exhibited mPFS of 9.20 months, versus 6.25 months in those with shorter prior treatment durations. Common treatment-emergent adverse events observed were hypertension (44.4%), proteinuria (22.2%), decreased platelets (22.2%), fatigue (11.1%), and hemoptysis (11.1%). Grade 3 adverse events included proteinuria (11.1%), fatigue (11.1%), and hemoptysis (11.1%). Conclusions: In patients with anlotinib-resistant RR-DTC, second-line surufatinib treatment yielded promising efficacy and tolerable toxicity, warranting randomized controlled studies on RR-DTC refractory to first-line targeted therapy. Clinical trial information: ChiCTR2100052020 .

Vimseltinib versus placebo for tenosynovial giant cell tumour (MOTION): a multicentre, randomised, double-blind, placebo-controlled, phase 3 trial

Tenosynovial giant cell tumour (TGCT) is a locally aggressive neoplasm for which few systemic treatment options exist. This study evaluated the efficacy and safety of vimseltinib, an oral, switch-control, CSF1R inhibitor, in patients with symptomatic TGCT not amenable to surgery. MOTION is a multicentre, randomised, double-blind, placebo-controlled, phase 3 trial done in 35 specialised hospitals in 13 countries. Eligible patients were adults (aged ≥18 years) with a histologically confirmed diagnosis of TGCT for which surgical resection could potentially worsen functional limitation or cause severe morbidity. Patients were randomly assigned (2:1) with interactive response technology to vimseltinib (30 mg orally twice weekly) or placebo, administrated in 28-day cycles for 24 weeks. Patients and site personnel were masked to treatment assignment until week 25, unless progressive disease was confirmed earlier. The primary endpoint was objective response rate by independent radiological review using Response Evaluation Criteria in Solid Tumors, version 1.1 (RECIST) at week 25 in the intention-to-treat population. Safety was assessed in all patients who received the study drug. The trial is registered with ClinicalTrials.gov, NCT05059262, and enrolment is complete. Between Jan 21, 2022, and Feb 21, 2023, 123 patients were randomly assigned (83 to vimseltinib and 40 to placebo). 73 (59%) patients were female and 50 (41%) were male. Nine (11%) of 83 patients assigned to vimseltinib and five (13%) of 40 patients assigned to placebo discontinued treatment before week 25; one patient in the placebo group did not receive any study drug. Objective response rate per RECIST was 40% (33 of 83 patients) in the vimseltinib group vs 0% (none of 40) in the placebo group (difference 40% [95% CI 29-51]; p<0·0001). Most treatment-emergent adverse events (TEAEs) were grade 1 or 2; the only grade 3 or 4 TEAE that occurred in more than 5% of patients receiving vimseltinib was increased blood creatine phosphokinase (eight [10%] of 83). One patient in the vimseltinib group had a treatment-related serious TEAE of subcutaneous abscess. No evidence of cholestatic hepatotoxicity or drug-induced liver injury was noted. Vimseltinib produced a significant objective response rate and clinically meaningful functional and symptomatic improvement in patients with TGCT, providing an effective treatment option for these patients. Deciphera Pharmaceuticals.

Updated efficacy and safety results from the phase Ib/II study of surufatinib combined with camrelizumab and chemotherapy in patients with advanced colorectal cancer.

e15547 Background: Preclinical and clinical data have demonstrated the synergistic anti-tumor effects of surufatinib, a novel VEGFR1-3, FGFR and CSF-1R inhibitor, in combination with immune checkpoint inhibitors (ICIs)/chemotherapy. A phase Ib/II, open-label study (NCT04929652) was conducted to evaluate the efficacy and safety of surufatinib plus camrelizumab (anti-PD-1), irinotecan and GM-CSF as second-line treatment in advanced colorectal cancer (CRC). In the phase Ib part, this combination showed favorable safety and efficacy profile, which was presented at ASCO 2023 in poster format (#255). Here, we reported the updated results from the phase Ib and phase II dose escalation part together. Methods: In the phase Ib, pts with CRC received surufatinib at 250mg once daily (QD) as starting dose, in combination with fixed dose of camrelizumab (200 mg, d1), irinotecan (200 mg/m2, d1) and GM-CSF (5ug/kg, d2-d7), every 3 weeks (Q3W). It had been reported in phase Ib that surufatinib 300 mg QD was defined as the recommended phase 2 dose (RP2D). In phase II dose expansion part, a further 36 pts were treated with the same regimen. The primary endpoint of phase II was ORR as per RECIST 1.1. Secondary endpoints included PFS, DCR, OS and safety. Results: As of Jan 18, 2024, 30 CRC pts (median age 57) were enrolled in the study with 12 pts in the phase Ib part and 18 pts in the phase II part. 70% were male and 23% had ECOG PS 1. 24/30 (80%) pts were positive for KRAS, NRAS or BRAF mutations. Among the 30 efficacy evaluable pts, the ORR was 30.0% (95% CI 14.7–49.4; 9 PR) and DCR was 93.3% (95% CI 77.9–99.2; 28 PR+SD). Pts with RAS/BRAF mutations were more likely to achieve better responses (9 PR in 24 pts, ORR-37.5%). After a median follow-up time of 11.1 months, the median PFS was 6.34 months (95% CI 4.57-9.23) and median OS was not mature. The most common grade 1-2 treatment related adverse events (TRAEs) (≥35%) were diarrhea (70%), fatigue (40%), anemia (36.7%), proteinuria (36.7%) and nausea (36.7%). Eleven pts experienced at least one grade 3 or 4 TRAEs. Grade 3 or 4 TRAEs occurred in &gt; 1 pt included diarrhea (n = 3, 10%) and neutrophil count decreased (n = 2, 6.7%). Conclusions: Surufatinib plus camrelizumab, irinotecan and GM-CSF demonstrated promising anti-tumor activity in pts with advanced CRC, with a manageable safety profile. Expansion enrollment is ongoing and updated information will be presented. Clinical trial information: NCT04929652 .