entospletinib (GS-9973)

Our study demonstrates that glioma cells can be activated by macrophages via SIRPB1, subsequently reprogramming the TME, suggesting that SIRPB1 could serve as a promising therapeutic target for gliomas.

This transporter-mediated restriction of brain penetration for both drugs could be almost fully inhibited by coadministration of the dual ABCB1/ABCG2 inhibitor elacridar, without signs of acute toxicity. This interaction was, however, unlikely to be mediated through any of the studied transporters or CYP3A. The obtained insights may perhaps help to further improve the safety and efficacy of entospletinib and lanraplenib.

Taken together, entospletinib abrogates dermal-epidermal separation, likely through inhibition of granulocyte responsiveness to deposited immune complexes. Entospletinib or other Syk inhibitors may provide therapeutic benefit in BP.

P1, N=203, Active, not recruiting, Gilead Sciences | Phase classification: P1b --> P1

Entospletinib (ENTO) and lanraplenib (LANRA) are inhibitors of spleen tyrosine kinase (SYK); the latter is a next-generation SYK inhibitor and is currently being evaluated in combination with gilteritinib (GILT) in patients with relapsed or refractory FLT3-mutated AML (NCT05028751)...Two different AML patient cohorts were assessed by ex vivo treatment with ENTO, LANRA and combinations of LANRA (trametinib, gilteritinib (GILT), aPD-1) over a range of time points (2h, 4h, 3d and 9d) and readouts for cellular phenotype (e.g., differentiation state, immune cell populations) and functional readouts (pSYK, viability) for each cohort were analyzed by HP-FC and sc-MI and associated with available mutation information (bulk gene and single cell RNA sequencing)...These support studies investigating the use of pSYK inhibitors in combination with other therapies to reduce tumor burden, and as an improved line of treatment for AML. Acknowledgements: We are appreciative of the patients and families for their time and participation.

In an orthotopic mouse model of FLT3-mutant AML, tuspetinib exhibited greater antitumor activity than gilteritinib, entospletinib, venetoclax (VEN), and azacitidine (AZA) and combined favorably with VEN and AZA individually. Tuspetinib was well-tolerated and delivered single agent clinical responses across four dose levels among diverse AML genotypes; with a RP2D of 80 mg chosen for future single agent studies. Although early, the VEN/TUS combination has been well tolerated with preliminary objective responses noted.

In our group’s previous study, human cell lines NALM-6 and SEM responded to SYK inhibition by Entospletinib (Ento) with proliferation suppression and apoptosis induction. Herein, we evaluated the effect of combined inhibition with pan-BET inhibitor I-BET151 (IBET) and evaluated their synergistic potential in canine and human B-ALL in vitro models... Canine and human B-ALL cell lines had similar responses to Ento and IBET single treatments, showing anti-proliferative effects on NALM-6, SEM, and GL-1. The inhibition of proliferation induced by Ento may act through the induction of apoptosis rather than cell cycle arrest. IBET induced both, strong apoptosis (except NALM-6) and cell cycle arrest.

The combination of entospletinib and decitabine demonstrated activity and was acceptably tolerated in this patient population; however, the CR rates were low, and overall survival was short. Novel treatment strategies for older patients with TP53 mutations and complex karyotype remain an urgent need.

P3, N=15, Terminated, Kronos Bio | Active, not recruiting --> Terminated; Termination was due to significant challenges associated with study enrollment in a genetic subset of fit participants in the front-line acute myeloid leukemia (AML) setting and other challenges associated with post-COVID impacts.

1, 2 Treatment of CLL cells with entospletinib, but not other BCR-signaling inhibitors, led to a disruption of BAFF-BCR cross-talk and downmodulation of MCL1 mRNA and protein, thus implicating SYK in transduction of multiple pro-survival signals emanating from the tumor microenvironment.1 Entospletinib has shown promising clinical activity in CLL, alone or in combination with obinutuzumab, including in patients with high-risk disease such as TP53 aberrant.3, 4 The drug is very well tolerated, however its development in CLL has been halted. Meanwhile, we have shown that luxeptinib, a dual SYK/BTK kinase inhibitor, has activity in BTK inhibitor-resistant lymphoid models in vitro.5 Luxeptinib is now being investigated in lcinical trials in hematologic malignancies...The early results of MS-553, a selective PKC-β inhibitor, indicates that this agent is tolerable and effective both as single agent and in combination with venetoclax.8 Proteolysis-targeting chimeras (PROTACs) are a new class of small molecules with two covalently-linked ligands recruiting target protein and E3 ubiquitin ligase together to trigger and enable proteasomal degradation of the target protein.9 “BTK degraders”, such as NRX- 2127 (Nurix Therapeutics) and BGB-16673 (Beigene), have entered clinical trials in patients with lymphoid malignancies...Additionally, NX-2127 has shown preclinical activity similar to immunomodulatory drugs (IMiDs) by catalyzing the ubiquitination of Ikaros (IKZF1) and Aiolos (IKZF3), resulting in increased T-cell activation.10 Early results of an ongoing clinical trial of NX-2127 demonstrate an ORR of 33% in heavily pre-treated patients with CLL, and overall good tolerability 11...The preclinical activity of AZD5991 has shown that selective targeting of MCL1 induced metabolic dysfunction and abrogated survival of diffuse large B cell lymphoma and ibrutinib-resistant mantle cell lymphoma cell lines in vivo and in vitro.13 Other BH3-mimetics targeting MCL1 include AMG176 and S63845.14-16 In an experimental design testing the effects of AMG-176 on CLL and normal hematopoietic cell death it was demonstrated that AMG-176 is an active agent in inducing CLL cell death while sparing normal blood cells...Anti-CD20 monoclonal antibodies – rituximab, obinutuzumab and ofatumumab – have significantly improved the survival outcomes. The B cell activating factor receptor (BAFF-R) is one of the main pro-survival receptors in B cells.18 In a preclinical study, ianalumab (VAY-736), a humanized defucosylated engineered antibody directed against BAFF-R, antagonized pro-survival effects of BAFF in CLL cells and showed promising activity both as a single agent and in combination with ibrutinib.19 A phase 1 study of dose escalation and dose expansion investigated the combination of ianalumab with ibrutinib in 32 patients with CLL with median one prior line of therapy (range, 0-4)...This study showed promising results not expected with ibrutinib alone.20 Tafasitamab – a Fc-enhanced, humanized, monoclonal antibody to CD19 – in combination with idelalisib or venetoclax in 24 patients has been associated with an ORR of 77% and 91%, respectively...In a phase 1 study involving 26 patients with R/R CLL, cirmtuzumab administered at four biweekly infusions was shown to have a long plasma half-life and did not have dose-limiting toxicity, potentially providing another treatment opportunity for patients with CLL.22 Immune Cell Enabling Therapies...A recent report of a phase 1/2 study of lisocabtagene maraleucel, an autologous CD19-directed CAR T-cell therapy (TRANSCEND CLL 004), confirmed efficacy in patients with R/R CLL.23 In this study, 23 patients with median 4 prior lines of therapy (range 2-11) were enrolled, 10 of whom were considered double exposed/refractory...In total, 65% of patients required administration of tocilizumab and/or corticosteroids.23 In addition to the ongoing phase 2 portion of this study, efforts now focus on innovative CAR T-cell designs as well as combination strategies...A phase 1b/2 ongoing trial is currently examining the safety and tolerability of the product in patients with R/R CLL. The early results suggest that epcoritamab administered subcutaneously is well tolerated in a heavily pretreated patient population with multiple high-risk features and shows clinical activity.25 Furthermore, an ongoing study is demonstrating preliminary efficacy of epcoritamab in patients with Richters transformation, a notoriously difficult-to-treat complication of CLL.26

Conclusions ABC transporters play an important role in the brain disposition of entospletinib and lanraplenib, although they have only a slight impact on the plasma exposure of entospletinib. The role for the OATP uptake transporters seems to be less prominent for both drugs, but they might be involved in the tissue disposition of lanraplenib, but not of entospletinib.

Furthermore, the high-risk subgroup was sensitive to sorafenib, selumetinib, and entospletinib. ssGSEA discovered that the processes of glutamine, arginine, tryptophan, cysteine, histidine, L-serine, isoleucine, threonine, tyrosine, and L-phenylalanine metabolism were more active in the high-risk subgroup. This study revealed that AA metabolism-related genes were correlated with the immune microenvironment of AML patients and could predict the prognosis and immunotherapy response of AML patients.

In this study, we evaluated the in vitro antileukemic effects of five SYK inhibitors, fostamatinib, entospletinib, cerdulatinib, TAK-659, and RO9021, in a consecutive AML patient cohort. Finally, most of the SYK inhibitors caused a significant decrease in the release of cytokines and chemokines from primary AML cells, indicating a potent inhibitory effect on the release of these leukemic signaling molecules. We concluded that the SYK inhibitors had antileukemic effects in AML, although larger studies are strongly needed to identify which patient subsets will benefit most from such a treatment.

P3, N=15, Active, not recruiting, Kronos Bio | Recruiting --> Active, not recruiting | N=180 --> 15 | Trial completion date: Dec 2026 --> Jun 2023 | Trial primary completion date: Dec 2023 --> Jun 2023

In a preclinical xenograft and orthotopic model of AML, HM43239 exhibited greater antitumor potency than FLT3 inhibitor gilteritinib, SYK inhibitor entospletinib, BCL-2 inhibitor venetoclax, and demethylation agent azacitidine. As of July 14, 2022, HM43239 has delivered CRc at 80 mg, 120mg and 160 mg, and was well tolerated at these dose levels over multiple cycles with no DLTs or drug-related SAEs. Pharmacokinetic data illustrate increasing drug exposures through 120 mg and observed objective responses through 160 mg in both FLT3-WT and FLT3-mutated R/R AML patients even after gilteritinib and midostaurin treatment. An update of this study, including a planned single agent and venetoclax combination expansion, will be presented at the meeting.

Introduction: Spleen tyrosine kinase (SYK) acts as a key integrator of cellular signaling from surface contact and receptor tyrosine kinase receptors containing an immunoreceptor tyrosine-based activation motif (ITAM). SYK is a promising therapeutic target for genetically defined subsets of AML. Two highly selective SYK inhibitors are currently undergoing clinical testing in different but complementary clinical settings. Given its central role as a modulator of leukemogenic signaling, SYK inhibition has the potential to synergize with other targeted therapies in AML.

ENTO with 7+3 IND and Ara-C CON therapy demonstrated a high CCR rate and encouraging mOS in ND NPM1+/FLT3-ITD- AML pts up to age 75. Stage 1 of the study was positive, allowing enrollment into Stage 2 however Stage 2 of this study is not currently being pursued to prioritize enrollment onto the global registrational Phase 3 double-blind study of ENTO in Combination With Intensive Induction and Consolidation Chemotherapy (NCT05020665) assessing MRD negative CR in NPM1+ AML pts.

One genomic group identified in AML that has primary and acquired secondary resistance to targeted therapies (i.e., enasidenib, venetoclax, gilteritinib, and entospletinib) are patients with a protein tyrosine phosphatase non-receptor type 11 (PTPN11) mutation. This mouse model emphasizes the importance of understanding the molecular heterogeneity of AML. The Ptpn11E76K/Npm1cA mice will be used to understand how different clonal populations interact to promote AML development and is a valuable tool for drug development.

We evaluated the anti-lymphoma activity of the isoform-specific bivalent BET inhibitor AZD5153 (AZD) and the pan-BET inhibitor I-BET151 (I-BET) as single agents and in combination with SYK inhibitor Entospletinib (Ento) in vitro. Genes such as ADGRA2, MYB, TNFRSF11A, S100A10, PLEKHH3, DHRS2 and FOXP1-AS1 were identified as possible key regulators. Simultaneous inhibition of BET and SYK enhanced the anti-proliferative effects, and induced a combination-specific gene expression signature.

It has also been studied in combination with idelalisib or entospletinib in CLL and other B-cell lymphomas though without clear benefi t for the combinations over monotherapy16,17. Tirabrutinib is approved in Japan for WM, lymphoplasmacytic lymphoma (LPL), and RRPCNSL, and in South Korea for RR-PCNSL18. TG-1701 is a selective covalent BTKi that has been studied as a monotherapy and in combination with ublituximab and umbralisib with preliminary results suggesting both effi cacy and manageable safety19. Orelabrutinib, another selective covalent BTKi, has been studied as a monotherapy in CLL in addition to other B-cell malignancies, also with favorable safety and effi cacy20,21 and it is approved in China for rel/ref CLL and MCL22. Finally, DTRMWXHS-12 is a covalent BTKi that uniquely is being studied in combination with everolimus and pomalidomide (triplet referred to as DTRM-555), given that this combination was determined to lead to synthetic lethality in both in vivo and in vitro screening studies, with safety and activity seen in early studies23,24...This resistance mechanism appears shared among available irreversible BTK inhibitors including ibrutinib, acalabrutinib and zanubrutinib26...Three such inhibitors have completed phase 1 studies in CLL: vecabrutinib, nemtabrutinib, and pirtobrutinib with another currently in phase 1, luxeptinib...Subsequently, pirtobrutinib is being further studied as both a monotherapy and in combination with venetoclax-rituximab in phase 3 trials in both the frontline and relapsed/refractory settings in CLL in addition to MCL...These non-C481 BTK mutations conferred resistance across multiple non-covalent BTKi’s (in addition to pirtobrutinib, vecabrutinib, nemtabrutinib and fenebrutinib were tested) in addition to variable levels of resistance to covalent BTKi’s36...This is being accomplished by improved tolerability, allowing for patients to stay on drug for longer, and potentially improved effi cacy, including activity despite acquisition of C481 resistance mutations, in the case of the non-covalent inhibitors. The non-covalent inhibitors would help fi ll a major area of unmet need for CLL patients progressing on covalent BTK inhibitors who are not candidates for or progress following venetoclax therapy.

"Kronos Bio...and Invivoscribe, a global provider of diagnostic kits and services for oncology, today announced their agreement to develop a companion diagnostic (CDx) for use with Kronos Bio's investigational therapy, entospletinib....The diagnostic will screen for the NPM1 mutation, which is present in approximately one-third of all patients with AML....Entospletinib is currently being studied in the Phase 3 AGILITY registrational study, with data anticipated in second half of 2023."

Idelalisib and ibrutinib had complementary effects on the BCR signaling cascade which was further reduced upon dasatinib and entospletinib treatment. The characterization of the molecular circuitry of leukemic BCR signaling will allow a more refined targeting of this Achilles heel.

The selective, orally bioavailable SYK inhibitor entospletinib (ENTO) has demonstrated clinical activity and tolerability in HOXA9/MEIS1- driven AML...Lanraplenib (LANRA) is a next-generation SYK inhibitor with similar potency and selectivity to ENTO but with more favorable pharmacologic properties that is currently being evaluated in combination with gilteritinib in patients with relapsed or refractory (R/R) FLT3 -mutated AML (NCT05028751)...Results Kinase selectivity profiling found >10-fold higher selectivity of ENTO and LANRA for SYK vs other kinases with improved potency and selectivity compared with the approved first-generation agent, fostamatinib...Combinations with AML standard-of-care and investigational agents, including azacytidine, showed at least additive effects. Strong synergy with the JAK inhibitor ruxolitinib was consistent mechanistically with a reporter model that demonstrated the ability of LANRA to block activation of STAT5 in response to proleukemic paracrine signaling. Finally, robust synergy across a range of LANRA concentrations was found when paired with venetoclax and gilteritinib...The highly predictive response for SYK inhibition with concurrent NPM1 m/ FLT3 -ITD mutations and synergy with gilteritinib observed in patient derived models is supportive of its clinical evaluation in combination with a FLT3 inhibitor. Our work supports the rationale for an ongoing Phase 1b/2 study of LANRA in combination with gilteritinib in patients with R/R FLT3 -mutated AML.

Methods AGILITY is a global, multi-center, double-blind, placebo-controlled trial of ENTO in combination with cytarabine plus daunorubicin or idarubicin induction (7+3) and age-adjusted high-dose cytarabine (HiDAC) consolidation in newly diagnosed AML pts aged 18–74 who are candidates for intensive induction and harbor a documented NPM1 mutation. Results Trial in progress. Conclusion Accrual is ongoing.

The selective, orally bioavailable SYK inhibitor entospletinib (ENTO) has demonstrated clinical activity and tolerability in HOXA9/MEIS1- driven AML...Lanraplenib (LANRA) is a next-generation SYK inhibitor with similar potency and selectivity to ENTO but with more favorable pharmacologic properties that is currently being evaluated in combination with gilteritinib in pts with relapsed or refractory FLT3 -mutated AML (NCT05028751)...Our studies illustrate that ENTO and LANRA may restore T-cell proliferation in a subset of AML pts with dysfunctional T-cell responses, suggesting a novel mechanism of action. Additional studies are required to fully understand the mechanism of SYK-mediated antitumor immune responses in AML.

We have evaluated the ability of the small molecule SYK inhibitor GS9973 in a variety of models. In addition, we found that inhibition of MoMFs SYK impairs the expression of CXCL1, on one hand, it reduces the recruitment of CD11bhiLy6Chi inflammatory cells, and on the other hand, it promotes the phenotype cross-dress process of pro-resolution MoMFs, thereby remodeling the chronic inflammatory environment of the fibrotic liver. Our further findings indicate that on the basis of the administration of CCR2/CCR5 dual inhibitor Cenicriviroc, further inhibiting MoMFs SYK may give patients with fibrosis additional benefits.

P3, N=180, Recruiting, Kronos Bio | Not yet recruiting --> Recruiting

Matrix combination assays were performed by combining ENTO or LANRA with either cytarabine ( NPM1 mut), gilteritinib ( FLT3 mut), or trametinib ( RAS mut) with cell viability and death assessed after a 3-day incubation period. These results support the clinical evaluation of LANRA in genetically defined subsets of AML. A phase 1b/2 study of LANRA in combination with the selective FLT3 inhibitor gilteritinib, in patients with relapsed or refractory FLT3 mut AML is planned for the end of this year.

Seven patients had received prior ibrutinib (4 patients discontinued due to intolerance and 2 due to progression). Thus, the combination of entospletinib and obinutuzumab shows an acceptable safety profile. Efficacy of this combination (EFS 27.5 months in predominantly high-risk population ) compares favorably with chlorambucil/obinutuzumab in R/R CLL (13 months), thus warranting continued exploration of the regimen.

AGILITY will be a global, multi-center, double-blind, placebo-controlled trial of ENTO in combination with cytarabine plus daunorubicin or idarubicin induction (7+3) and age-adjusted high-dose cytarabine (HiDAC) consolidation in newly diagnosed AML patients aged 18–75 years who are candidates for intensive induction and harbor a documented NPM1 mutation based on local or central mutation testing. Patients with co-mutated FLT3 (internal tandem duplication or tyrosine kinase domain) and for whom midostaurin with 7+3 is indicated are excluded...Key exploratory endpoints will be the correlation between recurring genomic mutations and response or progression and longitudinal assessment of peripheral blood for detection of NPM1- m alleles among patients who achieve MRD-negative CR post-induction. An independent data-monitoring committee will monitor emerging safety and efficacy data from this trial on an ongoing basis.

ENTO + DEC demonstrated activity in ND AML pts aged ≥60 years with TP53m ± CK and CK without TP53 but induced low CR/CRh rates and short OS consistent with previously published poor CR rates and OS in these pts. Our results differ from the high remission rate and longer OS previously reported for DEC monotherapy in AML pts with TP53m. ENTO + DEC was safe and acceptably tolerated.

Lastly, we evaluated the rational combination of Silybin and GS-9973 in the treatment of CCl4 induced mice and found that this combination is well tolerated and acts synergistically against HSCs activity, LF and HCC. The combinational use of Silybin and GS-9973 could be a promising therapeutic strategy in patients suffering from LF and even HCC.

No abstract available

AZD5991 is a highly selective BH3-mimetic that demonstrates high in vitro potency in MCL1-dependent cell lines with an IC50 <1 nM.7 We have demonstrated that direct MCL1 inhibition with AZD5991 disrupts survival of neoplastic B-cells in lymph-node mimicking conditions, induces mitochondrial dysfunction and cooperates with BCL2/X inhibitors in vitro and in vivo.8 A phase 1 clinical trial of AZD5991 alone or in combination with venetoclax in hematologic malignancies is ongoing (NCT03218683)...AMG-176 demonstrated synergy with venetoclax in AML models; however, it also caused cytopenias.9 AMG-176 was shown to induce apoptosis of CLL cells independent of prognostic markers and overcame the protective effect of stromal microenvironment.10 However, suppressive effects on hematopoiesis will likely become the dose- limiting factor in clinical trials of MCL1-targeting agents. The effect of MCL1 inhibition on cord blood-derived CD34+ cells was studied using a small-molecule inhibitor, S63845,11 resulting in almost complete depletion of human hematopoietic stem and progenitor cells, while mature blood cells survived normally...We have shown that SYK inhibition with entospletinib leads to downmodulation of MCL1 protein in CLL both in vitro and in the clinic.12,13 Treatment of CLL cells with entospletinib, but not other BCR-signaling inhibitors, led to a disruption of BAFF-BCR cross-talk and downmodulation of MCL1 mRNA and protein, thus implicating SYK in transduction of multiple pro-survival signals emanating from the tumor microenvironment.13 Entospletinib has shown promising clinical activity in CLL.12,14 It is currently being developed in myeloid malignancies.15 A novel dual SYK/BTK inhibitor luxeptinib also was shown to downregulate MCL1 and other pro-survival BCL2 proteins in CLL.16 Transcriptional cyclin-dependent kinases (CDK7/9) regulate activity of RNA polymerase, thereby controlling production of mRNA. Downmodulation of MCL1 has been considered a key mechanistic event accounting for the pro-apoptotic activity of CDK inhibitors in neoplastic B-cells.17,18 Pan-CDK inhibitors (flavopiridol, dinaciclib) demonstrate clinical efficacy in lymphoid malignancies. We and others reported that preclinical efficacy of AZ5576, a selective inhibitor of CDK9, and its clinical congener AZD4573 in lymphoid tumors depended on rapid downmodulation of MCL1, BFL1, and MYC.19–21 CDK9 inhibition can increase efficacy of BH3-mimetics, but safety of this combination will need to be explored.22,23 CDK9 inhibitors in development, in addition to AZD4573, include VIP152, CYC065, and voruciclib...Navitoclax is a small-molecule inhibitor of BCL2, BCLX, and BCL2L2; however, its use in CLL has been plagued by thrombocytopenia.24 AZD4320 is an alternative agent that co-targets BCL2/X...ABBV-155, an antibody-drug conjugate targeting BCLX, where BCLX is being used as a payload to avoid “off-tumor” effects, demonstrated promise in solid tumor models.26 Finally, as many microenvironment-driven pro-survival pathways converge on NFB, leading to induction of chemokines, cell cycle regulators, and BCL2 family proteins themselves, this transcription factor continues to be an attractive target in CLL...When combined with ibrutinib in murine CLL models, VAY-736 produced prolonged survival compared with either therapy alone.28 Alternative targets for therapeutic antibodies include ROR1 (cirmtuzumab), CD19 (tafasitamab), and others.29 As resistance to novel agents is becoming an unmet need in CLL, exploration of novel targets is of paramount importance...Multiple CDK inhibitors are currently being explored and have anti-tumor effects not restricted to MCL1 inhibition. CAR T cells and bi-specific antibodies have exceptional efficacy in lymphoid malignancies and thus are of high relevance in CLL.

Interestingly, the spleen tyrosine kinase (SYK) inhibitor entospletinib, and the phosphoinositide 3-kinase delta (PI3Kδ) inhibitor idelalisib, reduced T cell activation, impaired the generation of leukemic cells with this aggressive phenotype, and were able to restore CLL sensitivity to venetoclax. Our data highlight a novel combination to overcome resistance to venetoclax in CLL.

P3, N=180, Not yet recruiting, Kronos Bio

In vitro, 3 μM of GS-9973 reversed the drug resistance of NCI-H460/MX20 cell line to mitoxantrone or doxorubicin. Finally, HPLC analysis proved that the intracellular concentration of GS-9973 is not significantly different in both parental and resistant cell lines. In conclusion, our study suggests that in vitro, GS-9973 in combination with certain anticancer drugs, represent a strategy to overcome ABCG2-mediated MDR cancers.

Thus, SYK inhibition downmodulates Mcl-1 and partially restores T-cell immunity in CLL. Trial registration number NCT03010358.

P1/2, N=24, Completed, Alexey Danilov, MD | Active, not recruiting --> Completed | Trial completion date: Feb 2024 --> Apr 2021 | Trial primary completion date: Feb 2022 --> Apr 2021