Development of a selective S1P1 receptor agonist, Syl930, as a potential therapeutic agent for autoimmune encephalitis

Evaluation of proximod, a selective agonist of sphingosine-1-phosphate receptor-1, in healthy volunteers and patients with rheumatoid arthritis: a phase 1, double-blind, randomised, placebo-controlled, ascending dose trial

BACKGROUND

Proximod is a selective agonist of sphingosine-1-phosphate receptor-1 (S1PR1). It acts by redirecting lymphocytes from the circulation to secondary lymph nodes, and is under development as an immunomodulator for rheumatoid arthritis. We aimed to evaluate the safety, pharmacokinetics, and preliminary efficacy of proximod in healthy volunteers and patients with rheumatoid arthritis.

METHODS

We did a two part, phase 1, double-blind, randomised, placebo-controlled, ascending dose trial at a single centre in China. Eligible participants were adults aged 18-50 years with a BMI of 18-28 kg/m2 for healthy volunteers and aged 18-70 years with a BMI of 18-30 kg/m2 for patients with rheumatoid arthritis. In part 1, healthy volunteers were randomly assigned within ten cohorts to receive a single oral dose of proximod (0·125 mg, 0·25 mg, 0·5 mg, 1 mg, 1·5 mg, 2 mg, 3 mg, 5 mg, 10 mg, or 15 mg in cohorts 1-10) or placebo. In part 2, healthy volunteers were randomly assigned to receive once-daily doses of proximod 5 mg or placebo, and patients with rheumatoid arthritis were randomly assigned to receive once-daily doses of proximod 5 mg, proximod 10 mg, or placebo, for 28 days. Patients and investigators were masked to treatment assignment. The primary outcomes were safety, tolerability, and pharmacokinetic profile of proximod for 72 days in healthy volunteers and for 48 days in patients with rhematoid arthritis, assessed in all treated participants. This trial is registered with ClinicalTrials.gov (NCT06361199, NCT06361186), and is complete.

FINDINGS

Between Nov 1, 2017, and June 22, 2021, 124 healthy volunteers were randomly assigned in part 1 of the study and 124 were included in the analyses (mean age 34·3 years [SD 6·9], 62 [50%] of 124 participants were women and 62 [50%] were men, and 116 [94%] were Han Chinese ethnicity). Between Feb 16, 2022, and Oct 8, 2023, 113 participants were screened for inclusion in part 2 (80 healthy volunteers and 33 patients with rheumatoid arthritis). 79 participants were excluded and 34 were randomly assigned (10 healthy participants and 24 patients with rheumatoid arthritis), 34 of whom were included in the analyses. Ten (100%) of ten healthy participants were Han Chinese ethnicity, with a mean age of 39·9 years (SD 7·3). Five (50%) of ten healthy volunteers were women and five (50%) were men). 22 (92%) of 24 participants with rheumatoid arthritis were Han Chinese ethnicity, with a mean age of 52·7 years (SD 6·8). 22 (92%) of 24 patients with rheumatoid arthritis were women and two (8%) were men. In part 1, all doses of proximod were well tolerated, with no dose-related adverse reactions or serious adverse events observed. In part 2, 74 adverse reactions were reported in eight (80%) of ten healthy volunteers and 22 (92%) of 24 patients with rheumatoid arthritis. Adverse events associated with proximod were predominantly mild or moderate. In part 2, the concentration of proximod and its active metabolite, proximod-phosphate, gradually increased in all three groups receiving proximod and the EC50 of the S1PR1 agonist for proximod-phosphate (6·1 ng/mL) was reached on day 14 for both 5 mg groups, and on day 7 for the 10 mg group. The mean Ctrough values for proximod-phosphate on day 28 were 7·7 ng/mL and 10·2 ng/mL for 5 mg in healthy volunteers and patients with rheumatoid arthritis, respectively, and 15·3 ng/mL for 10 mg in patients with rheumatoid arthritis. In patients with rheumatoid arthritis, lymphocyte count decreased after treatment in all proximod groups reaching nadir at approximately day 28, with a corresponding percentage decline from baseline of 65·25% in the 5 mg group, 71·64% in the 10 mg group, and 20·57% in the placebo group.

INTERPRETATION

Proximod exhibited good tolerability over the 28-day treatment period, demonstrating its potential in reducing blood lymphocyte count. These results highlight the promise of the S1PR1 agonist proximod as a potential candidate for rheumatoid arthritis treatment, warranting further investigation in subsequent clinical studies.

FUNDING

Beijing Union Pharmaceutical Factory and Jian Kuan (Suzhou) Biotechnology.

The Current Landscape in the Development of Small-molecule Modulators Targeting Sphingosine-1-phosphate Receptors to Treat Neurodegenerative Diseases

Sphingosine 1-phosphate (S1P) is extensively researched as a lysophospholipid and is crucial in various physiological and pathological processes. It achieves this via signalling through five different subtypes of G protein-coupled receptors (GPCRs), namely S1PR1 to S1PR5. S1PR modulators possess the ability to traverse the blood-brain barrier, potentially leading to direct actions within the Central Nervous System (CNS). S1PR modulators specifically bind to receptors located on the surface of naive and central memory lymphocytes, causing these cells to be trapped or confined within the lymph node. The investigation of the S1P pathway has resulted in the approval of three S1PR modulators, namely fingolimod, siponimod, and ozanimod, as medications for the treatment of patients suffering from Multiple Sclerosis (MS). Additionally, new S1PR modulators, such as ponesimod and etrasimod, are currently being developed and tested in clinical trials. Research on the creation of S1P modulators in neurodegenerative illnesses is ongoing as scientists continue to explore novel possibilities for selective S1P modulators. This study provides a concise overview of sphingolipid metabolism, the mechanism by which S1P receptors are affected, and the structural characteristics of several small molecule S1P modulators, with a particular focus on their structure-activity connections.

Insights into the metabolic characteristics of aminopropanediol analogues of SYLs as S1P1 modulators: from structure to metabolism

SYL927 and SYL930, two aminopropanediol analogues, are novel Sphingosine-1-phosphate receptor 1 (S1P₁) modulators with higher selectivity and pharmacological activity compared with FTY720. Although the immunosuppressive activity of SYLs has been well demonstrated, information regarding the metabolic fates of the two chemicals is limited except for the CYP-catalyzed hydroxylation of SYL930. In this study, the biotransformation schemes of the two promising chemicals were investigated and compared using liver microsomes, S9 fractions and recombinant enzymes, and relevant molecular mechanism was primarily demonstrated by ligand-enzyme docking analysis (CDOCKER). As a result, the hydroxylation at alkyl chain on oxazole ring by the action of CYPs was found for both SYLs in vivo. The SULT-catalyzed sulfonation of the hydroxide was observed for SYL927 while the ADH/ALDH-catalyzed oxidation was only discovered for SYL930. The docking analysis suggested that specific non-covalent forces and/or bonding conformations of the hydroxides with biomacromolecules might be involved in the disparate metabolism of SYLs. Exploring the metabolic characteristics will help clarify the substance base for efficacy and safety of the two drugs. The uncovered structure-metabolism relationship in this study may provide an implication for the design and optimization for other S1P modulators.

Design and synthesis of analogues of the sphingosine-1-phosphate receptor 1 agonist IMMH001 with improved phosphorylation rate in human blood

IMMH001, which is a prodrug for sphingosine-1-phosphate receptor 1 (S1P₁) agonist, is converted to the active form, its monophosphate ester (S)-IMMH001-P, by sphingosine kinase 1 (SphK1) and sphingosine kinase 2 (SphK2) in vivo. In this study, we designed head-piece-modified analogues of IMMH001 based on structural information and prepared them with an efficient modular synthetic strategy. The analogues showed higher phosphorylation rates in human blood than the parent compound. These results indicated that the pro-R hydroxymethyl in the head-piece-moiety of IMMH001 prevents the pro-S hydroxymethyl from being phosphorylated by the kinase and ATP. The analogues may have better therapeutic potential.

S1P1-selective agonist prodrug IMMH002 is phosphorylated in rats to form an S-configured enantiomer: Synthesis, verification, and biological activity of the in vivo active metabolite

IMMH002 (1), a prodrug for a sphingosine-1-phosphate receptor 1 (S1P₁) agonist, is converted to the monophosphate ester, which has an immunomodulatory effect. Starting from prochiral amino alcohol 1, racemic and enantiomerically pure phosphates of 1 were synthesized. Pure enantiomers were obtained after the chiral resolution of the key intermediate by chiral high-performance liquid chromatography and the absolute configuration was determined by circular dichroism. In the in vitro homogeneous time-resolved fluorescence-IP1 functional assay, the (S)-enantiomer showed much higher S1P₁ activity and selectivity than the (R)-enantiomer. In the pharmacokinetic study, the ex vivo o-phthaldialdehyde derivatization protocol showed that the phosphate of 1 in rats was the S-configured enantiomer with >99% enantiomeric excess.

S1PR1 as a Novel Promising Therapeutic Target in Cancer Therapy

Sphingosine-1-phosphate (S1P) can regulate several physiological and pathological processes. S1P signaling via its cell surface receptor S1PR1 has been shown to enhance tumorigenesis and stimulate growth, expansion, angiogenesis, metastasis, and survival of cancer cells. S1PR1-mediated tumorigenesis is supported and amplified by activation of downstream effectors including STAT3, interleukin-6, and NF-κB networks. S1PR1 signaling can also trigger various other signaling pathways involved in carcinogenesis including activation of PI3K/AKT, MAPK/ERK1/2, Rac, and PKC/Ca, as well as suppression of cyclic adenosine monophosphate (cAMP). It also induces immunological tolerance in the tumor microenvironment, while the immunosuppressive function of S1PR1 can also lead to the generation of pre-metastatic niches. Some tumor cells upregulate S1PR1 signaling pathways, which leads to drug resistant cancer cells, mainly through activation of STAT3. This signaling pathway is also implicated in some inflammatory conditions leading to the instigation of inflammation-driven cancers. Furthermore, it can also increase survival via induction of anti-apoptotic pathways, for instance, in breast cancer cells. Therefore, S1PR1 and its signaling pathways can be considered as potential anti-tumor therapeutic targets, alone or in combination therapies. Given the oncogenic nature of S1PR1 and its distribution in a variety of cancer cell types along with its targeting advantages over other molecules of this family, S1PR1 should be considered a favorable target in therapeutic approaches to cancer. This review describes the role of S1PR1 in cancer development and progression, specifically addressing breast cancer, glioma, and hematopoietic malignancies. We also discuss the potential use of S1P signaling modulators as therapeutic targets in cancer therapy.

A novel S1P1 modulator IMMH002 ameliorates psoriasis in multiple animal models

Psoriasis is characterized by abnormal proliferation of keratinocytes, as well as infiltration of immune cells into the dermis and epidermis, causing itchy, scaly and erythematous plaques of skin. The understanding of this chronic inflammatory skin disease remains unclear and all available treatments have their limitations currently. Here, we showed that IMMH002, a novel orally active S1P₁ modulator, desensitized peripheral pathogenic lymphocytes to egress signal from secondary lymphoid organs and thymus. Using different psoriasis animal models, we demonstrated that IMMH002 could significantly relieve skin damage as revealed by PASI score and pathological injure evaluation. Mechanistically, IMMH002 regulated CD3⁺ T lymphocytes re-distribution by inducing lymphocytes’ homing, thus decreased T lymphocytes allocation in the peripheral blood and skin but increased in the thymus. Our results suggest that the novel S1P₁ agonist, IMMH002, exert extraordinary capacity to rapidly modulate T lymphocytes distribution, representing a promising drug candidate for psoriasis treatment.

Phloroglucinol derivative compound 21 attenuates cuprizone-induced multiple sclerosis mice through promoting remyelination and inhibiting neuroinflammation

Multiple sclerosis (MS) is a chronic autoimmune demyelinating disease in the central nervous system. The myelin loss is mainly caused by dysfunction of oligodendrocytes and inflammatory responses of microglia and astrocytes further aggravate the demyelination. Current therapies for MS focus on suppressing the overactivated immune response but cannot halt the disease progress, so effective drugs are urgently needed. Compound 21 is a phloroglucinol derivative that has been proved to have an outstanding anti-inflammatory effect. The purpose of the present study is to investigate whether this novel compound is effective in MS. The cuprizone-induced model was used in this study to mimic the pathological progress of MS. The results showed that Compound 21 significantly improved the neurological dysfunction and motor coordination impairment. Luxol Fast Blue staining and myelin basic protein immunostaining demonstrated that Compound 21 remarkably promoted remyelination. In addition, Compound 21 significantly promoted oligodendrocytes differentiation. Furthermore, we found that Compound 21 decreased microglia and astrocytes activities and the subsequent neuroinflammatory response, indicating that the anti-inflammatory effect of Compound 21 was also involved in its neuro-protection. All the data prove that Compound 21 exerts protective effect on MS through promoting remyelination and suppressing neuroinflammation, indicating that Compound 21 might be a potential drug candidate for MS treatment.

Sphingosine-1-Phosphate Receptor Subtype 1 (S1P1) Modulator IMMH001 Regulates Adjuvant- and Collagen-Induced Arthritis

Sphingosine-1-phosphate receptor subtype 1 (S1P₁) is essential for lymphocyte egress from lymphoid organs into systemic circulation and provides a well-defined drug target for autoimmune disorders. IMMH001, also called SYL930, is a specific S1P₁/S1P₄/S1P₅ modulator. Here, we investigated the potential therapeutic effect of IMMH001 on rheumatoid arthritis (RA). IMMH001 rendered periphery blood lymphocytes insensitive to the egress signal from secondary lymphoid organs. Importantly, in both rat adjuvant-induced arthritis and collagen-induced arthritis models, IMMH001 treatment significantly inhibited the progression of RA and RA-associated histological changes in the joints of Sprague-Dawley rats, including hind paw swelling and arthritic index, and thus reduced the pathological score. Furthermore, IMMH001 markedly decreased proinflammatory cytokine and chemokine release from the damaged joints. These data demonstrated that IMMH001 is a promising drug candidate for RA treatment.

Fingolimod reduces neuropathic pain behaviors in a mouse model of multiple sclerosis by a sphingosine-1 phosphate receptor 1-dependent inhibition of central sensitization in the dorsal horn

Multiple sclerosis (MS) is an autoimmune-inflammatory neurodegenerative disease that is often accompanied by a debilitating neuropathic pain. Disease-modifying agents slow down the progression of multiple sclerosis and prevent relapses, yet it remains unclear if they yield analgesia. We explored the analgesic potential of fingolimod (FTY720), an agonist and/or functional antagonist at the sphingosine-1-phosphate receptor 1 (S1PR1), because it reduces hyperalgesia in models of peripheral inflammatory and neuropathic pain. We used a myelin oligodendrocyte glycoprotein 35 to 55 (MOG35-55) mouse model of experimental autoimmune encephalomyelitis, modified to avoid frank paralysis, and thus, allow for assessment of withdrawal behaviors to somatosensory stimuli. Daily intraperitoneal fingolimod reduced behavioral signs of central neuropathic pain (mechanical and cold hypersensitivity) in a dose-dependent and reversible manner. Both autoimmune encephalomyelitis and fingolimod changed hyperalgesia before modifying motor function, suggesting that pain-related effects and clinical neurological deficits were modulated independently. Fingolimod also reduced cellular markers of central sensitization of neurons in the dorsal horn of the spinal cord: glutamate-evoked Ca signaling and stimulus-evoked phospho-extracellular signal-related kinase ERK (pERK) expression, as well as upregulation of astrocytes (GFAP) and macrophage/microglia (Iba1) immunoreactivity. The antihyperalgesic effects of fingolimod were prevented or reversed by the S1PR1 antagonist W146 (1 mg/kg daily, i.p.) and could be mimicked by either repeated or single injection of the S1PR1-selective agonist SEW2871. Fingolimod did not change spinal membrane S1PR1 content, arguing against a functional antagonist mechanism. We conclude that fingolimod behaves as an S1PR1 agonist to reduce pain in multiple sclerosis by reversing central sensitization of spinal nociceptive neurons.

Asymmetric amination of α,α-dialkyl substituted aldehydes catalyzed by a simple chiral primary amino acid and its application to the preparation of a S1P1 agonist

The chiral catalytic amination of an α,α-dialkyl substituted aldehyde usually proceeds with low enantioselectivity. We selected naphthyl-l-alanine as the catalyst and observed improved enantioselectivity for the amination. Using this method, racemic α-methyl-α-benzyloxypropanal was aminated to give chiral serine derivatives in 74% ee, which was further increased to >99% ee after recrystallization. Moreover, we also successfully synthesized a chiral phosphonium salt 9 for the preparation of one α-substituted alaninol compound 14 as an S1P₁ agonist in high overall yield.

The chiral catalytic amination of an α,α-dialkyl substituted aldehyde usually proceeds with low enantioselectivity.

Sequestration of T cells in bone marrow in the setting of glioblastoma and other intracranial tumors

T-cell dysfunction contributes to tumor immune escape in patients with cancer and is particularly severe amidst glioblastoma (GBM). Among other defects, T-cell lymphopenia is characteristic, yet often attributed to treatment. We reveal that even treatment-naïve patients and mice with GBM can harbor AIDS-level CD4 counts, as well as contracted, T-cell deficient lymphoid organs. Missing naïve T-cells are instead found sequestered in large numbers in the bone marrow. This phenomenon characterizes not only GBM but a variety of other cancers, although only when tumors are introduced into the intracranial compartment. T-cell sequestration is accompanied by tumor-imposed loss of S1P1 from the T-cell surface and is reversible upon precluding S1P1 internalization. In murine models of GBM, hindering S1P1 internalization and reversing sequestration licenses T-cell-activating therapies that were previously ineffective. Sequestration of T-cells in bone marrow is therefore a tumor-adaptive mode of T-cell dysfunction, whose reversal may constitute a promising immunotherapeutic adjunct.

Sphingolipids Are Dual Specific Drug Targets for the Management of Pulmonary Infections: Perspective

Sphingolipids are the major constituent of the mucus secreted by the cells of epithelial linings of lungs where they maintain the barrier functions and prevent microbial invasion. Sphingolipids are interconvertible, and their primary and secondary metabolites have both structural and functional roles. Out of several sphingolipid metabolites, sphingosine-1 phosphate (S1P) and ceramide are central molecules and decisive for sphingolipid signaling. These are produced by enzymatic activity of sphingosine kinase-1 (SK-1) upon the challenge with either biological or physiological stresses. S1P and ceramide rheostat are important for the progression of various pathologies, which are manifested by inflammatory cascade. S1P is a well-established secondary messenger and associated with various neuronal, metabolic, and inflammatory diseases other than respiratory infections such as Chlamydia pneumoniae, Streptococcus pneumoniae, and Mycobacterium tuberculosis. These pathogens are known to exploit sphingolipid metabolism for their opportunistic survival. Decreased sphingosine kinase activity/S1P content in the lung and peripheral blood of tuberculosis patients clearly indicated a dysregulation of sphingolipid metabolism during infection and suggest that sphingolipid metabolism is important for management of infection by the host. Our previous study has demonstrated that gain of SK-1 activity is important for the maturation of phagolysosomal compartment, innate activation of macrophages, and subsequent control of mycobacterial replication/growth in macrophages. Furthermore, S1P-mediated amelioration of lung pathology and disease severity in TB patients is believed to be mediated by the selective activation or rearrangement of various S1P receptors (S1PR) particularly S1PR2, which has been effective in controlling respiratory fungal pathogens. Therefore, such specificity of S1P-S1PR would be paramount for triggering inflammatory events, subsequent activation, and fostering bactericidal potential in macrophages for the control of TB. In this review, we have discussed and emphasized that sphingolipids may represent effective novel, yet dual specific drug targets for controlling pulmonary infections.

Synthesis, identification, and biological activity of metabolites of two novel selective S1P1 agonists

SYL927 and SYL930 are selective S1P1 agonists under preclinical development. However, during their pharmacokinetic studies we detected two metabolites in rat blood that were tentatively identified as monohydroxylated metabolites of SYL927 and SYL930 based on LC-MS/MS data. In this study, we designed and synthesized possible monohydroxylated products 6a-e and used them as references to confirm the structures of the two metabolites detected by LC-MS/MS. We also evaluated the in vitro and in vivo biological activities of these two metabolites.

Methods for Testing Immunological Factors

Hypersensitivity reactions can be elicited by various factors: either immunologically induced, i.e., allergic reactions to natural or synthetic compounds mediated by IgE, or non-immunologically induced, i.e., activation of mediator release from cells through direct contact, without the induction of, or the mediation through immune responses. Mediators responsible for hypersensitivity reactions are released from mast cells. An important preformed mediator of allergic reactions found in these cells is histamine. Specific allergens or the calcium ionophore 48/80 induce release of histamine from mast cells. The histamine concentration can be determined with the o-phthalaldehyde reaction.

AKP-11 - A Novel S1P1 Agonist with Favorable Safety Profile Attenuates Experimental Autoimmune Encephalomyelitis in Rat Model of Multiple Sclerosis

Sphingosine-1-phosphate receptor 1 (S1P1) mediated regulation of lymphocyte egress from lymphoid organs is recognized as the mechanism of FTY720 (Fingolimod, Gilenya) efficacy in relapsing-remitting forms of multiple sclerosis (RRMS). In this study we describe a novel S1P1 agonist AKP-11, next generation of S1P1 agonist, with immunomodulatory activities in cell culture model and for therapeutic efficacy against an animal model of MS, i.e. experimental autoimmune encephalomyelitis (EAE) but without the adverse effects observed with FTY720. Like FTY720, AKP-11 bound to S1P1 is internalized and activates intracellular AKT and ERKs cellular signaling pathways. In contrast to FTY720, AKP-11 mediated S1P1 downregulation is independent of sphingosine kinase activity indicating it to be a direct agonist of S1P1. The S1P1 loss and inhibition of lymphocyte egress by FTY720 leads to lymphopenia. In comparison with FTY720, oral administration of AKP-11 caused milder and reversible lymphopenia while providing a similar degree of therapeutic efficacy in the EAE animal model. Consistent with the observed reversible lymphopenia with AKP-11, the S1P1 recycled back to cell membrane in AKP-11 treated cells following its withdrawal, but not with withdrawal of FTY720. Accordingly, a smaller degree of ubiquitination and proteolysis of S1P1 was observed in AKP-11 treated cells as compared to FTY720. Consistent with previous observations, FTY720 treatment is associated with adverse effects of bradycardia and lung vascular leaks in rodents, whereas AKP-11 treatment had undetectable effects on bradycardia and reduced lung vascular leaks as compared to FTY720. Taken together, the data documents that AKP-11 treatment cause milder and reversible lymphopenia with milder adverse effects while maintaining therapeutic efficacy similar to that observed with FTY720, thus indicating therapeutic potential of AKP-11 for treatment of MS and related autoimmune disorders.

Quantitative determination of 2-amino-2-(2-(4'-(2-propyloxazol-4-yl)-[1,1'-biphenyl]-4-yl)ethyl)propane-1,3-diol and its active phosphorylated metabolite in rat blood by LC-MS/MS and application to PK/PD analysis

A sensitive and specific LC-MS/MS method was developed and validated for simultaneous determination of 2-amino-2-(2-(4'-(2-propyloxazol-4-yl)-[1,1'-biphenyl]-4-yl)ethyl)propane-1,3-diol (SYL930) and its active phosphate metabolite (SYL930-P) in rat blood using SYL927, an analogue of SYL930 as the internal standard. Blood samples were prepared by a simple protein precipitation with acetonitrile. The chromatographic separation was performed on a ZorbaxSB-C18 column (3.5 μm, 2.1 × 100 mm) with a gradient mobile phase of methanol/water containing 0.1 % formic acid (v/v) at a flow rate of 0.2 mL/min. The detection was carried out on a triple quadrupole tandem mass spectrometer equipped with electrospray ionization (ESI) in multiple reactions monitoring mode (MRM). The monitored transitions were 381.2 → 364.2 for SYL930, 461.2 → 334.2 for SYL930-P, and 367.1 → 350.4 for the internal standard, respectively. Good linearity was obtained for the analytes over the range of 0.2-100 ng/mL for SYL930 and 0.5-100 ng/mL for SYL930-P. The lower limits of quantitation (LLOQs) for SYL930 and SYL930-P were 0.2 and 0.5 ng/mL, respectively. The intra-day and inter-day precisions (RSD, %) of analytes were within 9.87 %, and the accuracy (RE, %) ranged from -7.04 to 13.15 %. The mean recoveries for two compounds in rat blood were 87.9-109 %. The analytes were proved to be stable during all sample storage, preparation, and analytic procedures. The validated method was successfully applied to pharmacokinetic and PK/PD studies of SYL930 and SYL930-P in rats after oral administration of SYL930. Graphical Abstract Quantitative determination of SYL930 and its active phosphorylated metabolite in rat blood by LCMS/MS and application to PK/PD analysis.

Overexpression of sphingosine-1-phosphate receptor 1 and phospho-signal transducer and activator of transcription 3 is associated with poor prognosis in rituximab-treated diffuse large B-cell lymphomas

Background

Sphingosine-1-phosphate receptor-1 (S1PR1) and signal transducer and activator of transcription-3 (STAT3) play important roles in immune responses with potential oncogenic roles.

Methods

We analyzed S1PR1/STAT3 pathway activation using immunohistochemistry in rituximab-treated diffuse large B-cell lymphomas (DLBCL; N = 103).

Results

Nuclear expression of pSTAT3 (but not S1PR1) was associated with non-GCB phenotype (p = 0.010). In univariate survival analysis, S1PR1 expression (S1PR1+) was a poor prognostic factor in total DLBCLs (p = 0.018), as well as in nodal (p = 0.041), high-stage (III, IV) (p = 0.002), and high-international prognostic index (IPI; 3–5) (p = 0.014) subgroups, while nuclear expression of pSTAT3 (pSTAT3+) was associated with poor prognosis in the low-stage (I, II) subgroup (p = 0.022). The S1PR1/pSTAT3 risk-categories, containing high-risk (S1PR1+), intermediate-risk (S1PR1-/pSTAT3+), and low-risk (S1PR1-/pSTAT3-), predicted overall survival (p = 0.010). This prognostication tended to be valid in each stage (p = 0.059 in low-stage; p = 0.006 in high-stage) and each IPI subgroups (p = 0.055 [low-IPI]; p = 0.034 [high-IPI]). S1PR1 alone and S1PR1/pSTAT3 risk-category were significant independent prognostic indicators in multivariate analyses incorporating IPI and B symptoms (S1PR1 [p = 0.005; HR = 3.0]; S1PR1/pSTAT3 risk-category [p = 0.019: overall; p = 0.024, HR = 2.7 for S1PR1-/pSTAT3+ vs. S1PR1+; p = 0.021, HR = 3.8 for S1PR1-/pSTAT3- vs. S1PR1+]).

Conclusions

Therefore, S1PR1 and S1PR1/pSTAT3 risk-category may contribute to risk stratification in rituximab-treated DLBCLs, and S1PR1 and STAT3 might be therapeutic targets for DLBCL.