Family Kinase Inhibitor Research Articles

Efficacy and safety of the oral JAK3/TEC family kinase inhibitor ritlecitinib over 24 months: integrated analysis of the ALLEGRO phase 2b/3 and long-term phase 3 clinical studies in alopecia areata.

The ALLEGRO phase 2a and 2b/3 studies demonstrated that ritlecitinib is efficacious and well tolerated in adult and adolescent patients with alopecia areata (AA) up to 48 weeks. The efficacy of ritlecitinib through Month 24 and safety through data cutoff were assessed in the ALLEGRO phase 2b/3 study and the ongoing long-term, open-label, phase 3 ALLEGRO-LT study. Patients aged ≥12 years with AA and ≥50% scalp hair loss from ALLEGRO-2b/3 who rolled over to ALLEGRO-LT after up to 48 weeks were included. Proportions of patients with responses based on clinician-reported Severity of Alopecia Tool (SALT) score of ≤20 and ≤10, eyebrow assessment (EBA) and eyelash assessment (ELA), patient global impression of change (PGI-C) and patient satisfaction with hair growth are reported through Month 24 for patients who received ritlecitinib 50 mg daily with or without a 200-mg 4-week daily loading dose. Observed and imputed data (last observation carried forward [LOCF]) were reported until December 9, 2022. Safety was assessed throughout. At Month 12, SALT score ≤20 was achieved by 45.1% and 45.9% (observed) and 40.3% and 41.8% (LOCF) of the 191 and 194 patients who received ritlecitinib 50 mg and ritlecitinib 200/50 mg, respectively. At Month 24, proportions increased to 60.8% and 63.1% (observed) and 46.1% and 50.8% (LOCF), respectively. Patients with abnormal EBA or ELA scores at baseline achieved responses at Month 24 (EBA observed: 57.6% [50 mg], 61.0% [200/50 mg]; EBA LOCF: 46.8% [50 mg], 50.9% [200/50 mg]; ELA observed: 51.2% [50 mg], 62.7% [200/50 mg]; ELA LOCF: 43.2% [50 mg], 51.7% [200/50 mg]). PGI-C response was achieved by patients at Month 24 (observed: 70.0% [50 mg], 76.4% [200/50 mg]; LOCF: 56.6% [50 mg], 65.5% [200/50 mg]). Safety profiles for both treatment groups were consistent with the known safety profile of ritlecitinib. Ritlecitinib has clinically meaningful and sustained efficacy beyond 1 year with a favourable safety and tolerability profile, supporting its long-term use in patients aged ≥12 years with AA. ClinicalTrials.gov: NCT03732807, NCT04006457.

Unlocking the potential: unveiling tyrphostins with Michael-reactive cyanoacrylate motif as promising inhibitors of human 5-lipoxygenase.

Human 5-lipoxygenase (5-LO) is the key enzyme in the biosynthesis of leukotrienes, mediators of the innate immune system that also play an important role in inflammatory diseases and cancer. In this study, we present compounds, containing a Michael-reactive cyanoacrylate moiety as potent inhibitors of 5-LO. Representatives of the tyrosine kinase inhibitor family called tyrphostins, structurally related to known 5-LO inhibitors, were screened for their 5-LO inhibitory properties using recombinant human 5-LO, intact human PMNL (polymorphonuclear leukocytes), and PMNL homogenates. Their mode of action was characterized by the addition of glutathione, using a fourfold cysteine 5-LO mutant and mass spectrometry analysis. SAR studies revealed several members of the tyrphostin family containing a Michael-reactive cyanoacrylate to efficiently inhibit 5-LO. We identified degrasyn (IC50 0.11µM), tyrphostin A9 (IC50 0.8µM), AG879 (IC50 78nM), and AG556 (IC50 64nM) as potent 5-LO inhibitors. Mass spectrometry analysis revealed that degrasyn and AG556 covalently bound to up to four cysteines, including C416 and/or C418 which surround the substrate entry site. Furthermore, the 5-LO inhibitory effect of degrasyn was remarkably impaired by the addition of glutathione or by the mutation of cysteines to serines at the surface of 5-LO. We successfully identified several tyrphostins as potent inhibitors of human 5-LO. Degrasyn and AG556 were able to covalently bind to 5-LO via their cyanoacrylate moiety. This provides a promising mechanism for targeting 5-LO by Michael acceptors, leading to new therapeutic opportunities in the field of inflammation and cancer.

Efficacy and safety of ritlecitinib, an oral JAK3/TEC family kinase inhibitor, in adolescent and adult patients with alopecia totalis and alopecia universalis.

This post-hoc analysis of the ALLEGRO phase 2b/3 study (NCT03732807) evaluated the efficacy and safety of ritlecitinib, an oral Janus kinase 3/TEC family kinase inhibitor, in patients with alopecia totalis (AT) and alopecia universalis (AU). Patients aged ≥ 12 years with alopecia areata (AA) and ≥50% scalp hair loss received once-daily ritlecitinib 50 or 30 mg (± 4-week 200-mg loading dose) or placebo for 24 weeks. In a subsequent 24-week extension period, the ritlecitinib groups continued their doses and patients initially assigned to placebo switched to ritlecitinib (200/50 or 50 mg daily). In this analysis, clinician- and patient-reported hair regrowth outcomes were assessed at weeks 24 and 48 in four AA subgroups: AT/AU, AT, AU, and non-AT/AU. Safety was monitored throughout. Of the 718 randomized patients, 151 (21%) and 147 (20%) were defined as having AT or AU, respectively. At week 24, Severity of Alopecia Tool (SALT) score ≤20 (≤20% scalp hair loss) response rates were higher in the ritlecitinib-treated AT/AU, AT, and AU groups (7%-14%, 7%-21%, and 4%-10%, respectively) vs the placebo group (0% in the AT/AU, AT, and AU groups). The proportions of patients with a SALT score of ≤20 increased through week 48 (AT/AU, 13%-31%; AT, 11%-27%; AU, 6%-41%). Additionally, at week 24, 25%-43%, 32%-42%, and 12%-50% of patients with AT/AU, AT, and AU, respectively, who received ritlecitinib achieved a moderately or greatly improved response based on the Patient Global Impression of Change scale. Response rates generally increased through week 48 and were similar across AA subgroups. In patients with AT/AU, ritlecitinib was well tolerated with a safety profile consistent with that of the overall AA population. Ritlecitinib demonstrated clinical efficacy, patient-reported improvement, and an acceptable safety profile in patients with AT and AU through week 48. A plain language summary of this study is available at https://doi.org/10.25454/pfizer.figshare.26879161. Clinicaltrials.gov: NCT03732807.

Impact of Previous Alopecia Areata Treatment on Efficacy Responses up to Week 48 Following Ritlecitinib Treatment: A Post Hoc Analysis.

Patients with alopecia areata (AA) may have received several therapies for management of AA during their lives. In the ALLEGRO phase 2b/3 (NCT03732807) study, the oral JAK3/TEC family kinase inhibitor ritlecitinib demonstrated efficacy and an acceptable safety profile in patients aged ≥ 12years with AA and ≥ 50% scalp hair loss. This post hoc analysis investigated associations between prior use of AA therapies and Severity of Alopecia Tool (SALT) responses in patients receiving ritlecitinib for AA. Patients receiving ritlecitinib 30mg or 50mg once daily with or without an initial 4-week 200-mg daily loading dose were grouped by previous exposure to AA treatments, including topicals, intralesional corticosteroids (ILCS), topical immunotherapy, and systemic immunosuppressants or any prior AA treatment. Multivariable logistic regression analyses evaluated the association between response based on a SALT score of ≤ 20 and any prior treatment for AA at weeks 24 and 48. Of 522 patients, 360 (69.0%) had previous exposure to any AA treatment. At Week 24, SALT ≤ 20 response was positively associated with prior use of ILCS (odds ratio [OR], 2.12; 95% confidence interval [CI], 1.23-3.65; P < 0.05) and negatively associated with prior use of systemic immunosuppressants (OR 0.50; 95% CI 0.28-0.88; P < 0.05). Prior use of topicals or topical immunotherapy was not associated with SALT ≤ 20 response at Week 24. By Week 48, no association was identified between SALT ≤ 20 response and prior use of topicals, ILCS, topical immunosuppressants, or systemic immunosuppressants (all P > 0.05). Previous exposure to any AA therapy was not associated with SALT ≤ 20 response at weeks 24 or 48 (all P > 0.05). Prior AA treatment history had no effect on longer-term treatment response to ritlecitinib. NCT03732807.

Efficacy and safety of ritlecitinib in vitiligo patients across Fitzpatrick skin types with biomarker analyses.

Efficacy and safety of ritlecitinib (an oral JAK3/TEC family kinase inhibitor) were evaluated in patients with nonsegmental vitiligo (NSV) across Fitzpatrick skin types (FSTs). Patients with FST I-III ('light skin'; n = 247) and FST IV-VI ('dark skin'; n = 117) received once-daily ritlecitinib 50 mg (with/without 4-week loading dose), low-dose ritlecitinib or placebo for 24 weeks. At baseline, patients with light skin displayed higher CLM-1 and NCR1 serum levels than patients with dark skin (p < 0.05). At 24 weeks, ritlecitinib 50 mg improved the extent of depigmentation measured by percent change from baseline in facial-vitiligo area scoring index (placebo-adjusted mean difference [90% CI]) in patients with light (-15.2 [-24.7, -5.8]; p = 0.004) and dark (-37.4 [-50.3, -24.4]; p < 0.0001) skin, with continuous re-pigmentation through week 48. Treatment-emergent adverse events were similar across FSTs. At weeks 4 and 24, ritlecitinib 50 mg reduced CXCL11 serum levels (p < 0.001) in patients with light skin, whereas patients with dark skin had increased levels at week 4 (p = 0.05) and no significant change at week 24. Ritlecitinib 50 mg decreased IL-9 and IL-22 expression levels in dark skin compared with light skin (qPCR; p < 0.05). These differences in immune dysregulations may explain why NSV patients with dark skin respond to therapy earlier than patients with light skin.

Molecular mechanisms driving the interactions between platelet and gastric cancer cells during peritoneal dissemination.

Platelets (PLTs) facilitate tumor progression and the spread of metastasis. They also interact with cancer cells in various cancer types. Furthermore, PLTs form complexes with gastric cancer (GC) cells via direct contact and promote their malignant behaviors. The objective of the present study was to explore the molecular mechanisms driving these interactions and to evaluate the potential for preventing peritoneal dissemination by inhibiting PLT activation in GC cells. The present study examined the roles of PLT activation pathways in the increased malignancy of GC cells facilitated by PLT-cancer cells. Transforming growth factor-β receptor kinase inhibitor (TRKI), Src family kinase inhibitor (PP2) and Syk inhibitor (R406) were used to identify the molecules influencing these interactions. Their therapeutic effects were verified via cell experiments and validated using a mouse GC peritoneal dissemination model. Notably, only the PLT activation pathway-related inhibitors TRKI and PP2, but not R406, inhibited the PLT-enhanced migration and invasion of GC cells. In vivo analyses revealed that PLT-enhanced peritoneal dissemination was suppressed by PP2. Overall, the present study revealed the important role of the Srk family in the interactions between PLTs and GC cells, suggesting kinase inhibitors as promising therapeutic agents to mitigate the progression of peritoneal metastasis in patients with GC.

The Pharmacokinetics, Metabolism, and Clearance Mechanisms of Ritlecitinib, a Janus Kinase 3 and Tyrosine-Protein Kinase Family Inhibitor, in Humans.

Ritlecitinib is an oral once-daily irreversible inhibitor of Janus kinase 3 and tyrosine-protein kinase family being developed for the treatment of moderate-to-severe alopecia areata. This study examined the disposition of ritlecitinib in male participants following oral and intravenous administration using accelerator mass spectroscopy methodology to estimate pharmacokinetic parameters and characterize metabolite profiles. The results indicated ritlecitinib had a systemic clearance of 43.7 L/h, a steady state volume of distribution of 73.8 L, extent of absorption of 89%, time to maximum plasma concentration of ∼0.5 hours, and absolute oral bioavailability of 64%. An observed long terminal half-life of total radioactivity was primarily attributed to ritlecitinib binding to plasma albumin. Ritlecitinib was the main circulating drug species in plasma (∼30%), with one major pharmacologically inactive cysteine conjugated metabolite (M2) at >10%. Oxidative metabolism (fractional clearance 0.47) and glutathione-related conjugation (fractional clearance 0.24) were the primary routes of elimination for ritlecitinib with the greatest disposition of radioactivity shown in the urine (∼71%). In vitro phenotyping indicated ritlecitinib cytochrome P450 (CYP) fraction of metabolism assignments of 0.29 for CYP3A, 0.09 for CYP2C8, 0.07 for CYP1A2, and 0.02 for CYP2C9. In vitro phenotyping in recombinant human glutathione S-transferases indicated ritlecitinib was turned over by a number of cytosolic and microsomal enzyme isoforms. SIGNIFICANCE STATEMENT: This study provides a detailed understanding of the disposition and metabolism of ritlecitinib, a JAK3 and TEC family kinase inhibitor for alopecia areata in humans, as well as characterization of clearance pathways and pharmacokinetics of ritlecitinib and its metabolites. As an AMS-based ADME study design, we have expanded on reporting the standard ADME endpoints, providing key pharmacokinetic parameters, such as clearance, volume of distribution, and bioavailability, allowing for a more comprehensive understanding of drug disposition.

A phase 2a study investigating the effects of ritlecitinib on brainstem auditory evoked potentials and intraepidermal nerve fiber histology in adults with alopecia areata.

Reversible axonal swelling and brainstem auditory evoked potential (BAEP) changes were observed in standard chronic (9-month) toxicology studies in dogs treated with ritlecitinib, an oral Janus kinase 3/tyrosine kinase expressed in hepatocellular carcinoma family kinase inhibitor, at exposures higher than the approved 50-mg human dose. To evaluate the clinical relevance of the dog toxicity finding, this phase 2a, double-blind study assessed BAEP changes and intraepidermal nerve fiber (IENF) histology in adults with alopecia areata treated with ritlecitinib. Patients were randomized to receive oral ritlecitinib 50 mg once daily (QD) with a 4-week loading dose of 200 mg QD or placebo for 9 months (placebo-controlled phase); they then entered the active-therapy extension and received ritlecitinib 50 mg QD (with a 4-week loading dose of 200 mg in patients switching from placebo). Among the 71 patients, no notable mean differences in change from baseline (CFB) in Waves I-V interwave latency (primary outcome) or Wave V amplitude on BAEP at a stimulus intensity of 80 dB nHL were observed in the ritlecitinib or placebo group at Month 9, with no notable differences in interwave latency or Wave V amplitude between groups. The CFB in mean or median IENF density and in percentage of IENFs with axonal swellings was minimal and similar between groups at Month 9. Ritlecitinib treatment was also not associated with an imbalanced incidence of neurological and audiological adverse events. These results provide evidence that the BAEP and axonal swelling finding in dogs are not clinically relevant in humans.

The SRC family kinase inhibitor NXP900 demonstrates potent antitumor activity in squamous cell carcinomas

NXP900 is a selective and potent SRC family kinase (SFK) inhibitor, currently being dosed in a phase 1 clinical trial, that locks SRC in the “closed” conformation, thereby inhibiting both kinase-dependent catalytic activity and kinase-independent functions. In contrast, several multi-targeted kinase inhibitors that inhibit SRC, including dasatinib and bosutinib, bind their target in the active “open” conformation, allowing SRC and other SFKs to act as a scaffold to promote tumorigenesis through non-catalytic functions. NXP900 exhibits a unique target selectivity profile with sub-nanomolar activity against SFK members over other kinases. This results in highly potent and specific SFK pathway inhibition. Here, we demonstrate that esophageal squamous cell carcinomas (ESCC) and head and neck squamous cell carcinomas (HNSCC) are exquisitely sensitive to NXP900 treatment in cell culture and in vivo, and we identify a patient population that could benefit from treatment with NXP900.

Targeting YES1 Disrupts Mitotic Fidelity and Potentiates the Response to Taxanes in Triple-Negative Breast Cancer.

Clinical trials examining broad-spectrum Src family kinase (SFK) inhibitors revealed significant dose-limiting toxicities, preventing advancement for solid tumors. SFKs are functionally heterogeneous, thus targeting individual members is a potential strategy to elicit anti-tumor efficacy while avoiding toxicity. Here, we identified that YES1 is the most highly overexpressed SFK in triple negative breast cancer (TNBC) and is associated with poor patient outcomes. Disrupting YES1, genetically or pharmacologically, induced aberrant mitosis, centrosome amplification, multi-polar spindles, and chromosomal instability (CIN). Mechanistically, YES1 sustained FOXM1 protein levels and elevated expression of FOXM1 target genes that control centrosome function and are essential for effective and accurate mitotic progression. In both in vitro and in vivo TNBC models, YES1 suppression potentiated the efficacy of taxanes, cornerstone drugs for TNBC that require elevated CIN for efficacy. Clinically, elevated expression of YES1 was associated with worse overall survival of TNBC patients treated with taxane and anthracycline combination regimens. Together, this study demonstrates that YES1 is an essential regulator of genome stability in TNBC that can be leveraged to improve taxane efficacy.

Ritlecitinib, a JAK3/TEC family kinase inhibitor, stabilizes active lesions and repigments stable lesions in vitiligo

The efficacy of ritlecitinib, an oral JAK3/TEC family kinase inhibitor, on active and stable lesions was evaluated in patients with active non-segmental vitiligo in a phase 2b trial (NCT03715829). Patients were randomized to placebo or daily ritlecitinib 50 mg (with or without 4-week 100-mg or 200-mg loading dose), 30 mg, or 10 mg for 24 weeks. Active lesions showed greater baseline expression of inflammatory/immune markers IFNG and CCL5, levels of CD103, and T-cell infiltrates than stable lesions. Patients with more active than stable vitiligo lesions showed higher baseline serum levels of CXCL9 and PD-L1, while patients with more stable than active lesions showed higher baseline serum levels of HO-1. At Week 24, ritlecitinib 50 mg significantly stabilized mean percent change from baseline in depigmentation extent in both active lesions and stable lesions vs. placebo-response, with stable lesions showing greater repigmentation. After 24 weeks of treatment, ritlecitinib 50 mg increased expression of melanocyte markers in stable lesions, while Th1/Th2-related and co-stimulatory molecules decreased significantly in both stable and active lesions. Serum from patients with more active than stable lesions showed decreased levels of ICOS and NK cell activation markers. These data, confirmed at transcription/protein levels, indicate that stable lesion repigmentation occurs early with ritlecitinib, while active lesions require stabilization of inflammation first. ClinicalTrials.gov: NCT03715829.

WEE Family Kinase Inhibitors Combined with Sorafenib Can Selectively Inhibit HCC Cell Proliferation

Background: Sorafenib is currently the first choice for the treatment of patients with advanced hepatocellular carcinoma, but its therapeutic effect is still limited. Objectives: This study aims to examine whether WEE family kinase inhibitors can enhance the anticancer effect of sorafenib. Methods: We analyzed the expression levels of PKMYT1 kinase and WEE1 kinase in HCC, studied the inhibitory effect of PKMYT1 kinase inhibitor RP-6306, WEE1 kinase inhibitor adavosertib combined with sorafenib on the proliferation of HCC cells, and detected the effect of drug combination on CDK1 phosphorylation. Results: We found that PKMYT1 and WEE1 were upregulated in HCC and were detrimental to patient survival. Cell experiments showed that both RP-6306 and adavosertib (1-100 μM) inhibited the proliferation of HCC cell lines in a dose-dependent manner alone, and the combination of the two drugs had a synergistic effect. In HCC cell lines, sorafenib combined with RP-6306 or adavosertib showed a synergistic antiproliferation effect and less toxicity to normal cells. Sorafenib combined with RP-6306 and adavosertib further inhibited the proliferation of HCC cells and caused complete dephosphorylation of CDK1. Conclusion: Taken together, our findings provide experimental evidence for the future use of sorafenib in combination with RP-6306 or adavosertib for the treatment of HCC.

A Review of JAK Inhibitors for Treatment of Alopecia Areata in the Military Health Care System.

Alopecia areata (AA) is a disease that manifests as patchy hair loss on the scalp and other parts of the body; severe disease may result in disfigurement, functional impairment, and significant psychological distress. This condition is understood to be caused by autoimmunity to the hair follicle and subsequent arrest of hair growth. New medications, baricitinib and ritlecitinib, belong to the Janus kinase (JAK) inhibitor family and are among the first FDA-approved treatments for severe AA. In this manuscript, we aim to answer the question: What treatment options exist for AA in the military health care system (MHS)? In doing so, we review the pathogenesis, physical and psychosocial impact of AA, conventional treatment of AA, and the efficacy and safety of baricitinib and ritlecitinib. A literature search was performed using PubMed, Embase, and Ovid for the history and pathogenesis of AA, psychosocial impact of disease, functional impairments, and current treatments. Keywords "alopecia areata," "current therapy for alopecia areata," "pathogenesis alopecia areata," "baricitinib," "ritlecitinib," "JAK inhibitor alopecia," "JAK inhibitor safety," "baricitinib efficacy," "alopecia eyelash," "alopecia nails," and "psychosocial impact of alopecia" were used for the search. The TRICARE manual was searched for guidelines applicable to the treatment of AA, DoD Instruction 6130.03 Volume 2 for medical standards for military service, and the U.S. Central Command Modification 15 for fitness of deployment to Central Command area of operations. Traditional treatments such as intralesional steroids may be effective for some patients, but difficulty lies in controlling extensive or refractory disease. Janus kinase inhibitors, baricitinib and ritlecitinib, are found effective at improving severe refractory disease; baricitinib induced hair regrowth in 32.6% more patients than placebo, and ritlecitinib was found to be superior to placebo by at least 24%. Currently, there is no coverage for therapeutic treatment of hair growth in the MHS. Additionally, military members are disqualified for continued service if they require immunomodulator medications such as baricitinib and ritlecitinib. Those on immunomodulators are unable to deploy worldwide. Baricitinib and ritlecitinib are effective treatments for widespread, progressive, and refractory AA. Although JAK inhibitors demonstrate improved effectiveness compared to non-immunomodulator treatments, their use in the MHS for this purpose is limited.

1,25-Dihydroxyvitamin D3 attenuates platelet aggregation potentiated by SARS-CoV-2 spike protein via inhibiting integrin αIIbβ3 outside-in signaling.

Platelet hyperreactivity contributes to the pathogenesis of COVID-19, which is associated with a hypercoagulability state and thrombosis disorder. It has been demonstrated that Vitamin D deficiency is associated with the severity of COVID-19 infection. Vitamin D supplement is widely used as a dietary supplement due to its safety and health benefits. In this study, we investigated the direct effects and underlying mechanisms of 1,25(OH)2D3 on platelet hyperreactivity induced by SRAS-CoV-2 spike protein via Western blot and platelet functional studies in vitro. Firstly, we found that 1,25(OH)2D3 attenuated platelet aggregation and Src-mediated signaling. We further observed that 1,25(OH)2D3 attenuated spike protein-potentiated platelet aggregation in vitro. Mechanistically, 1,25(OH)2D3 attenuated spike protein upregulated-integrin αIIbβ3 outside-in signaling such as platelet spreading and the phosphorylation of β3, c-Src and Syk. Moreover, using PP2, the Src family kinase inhibitor to abolish spike protein-stimulated platelet aggregation and integrin αIIbβ3 outside-in signaling, the combination of PP2 and 1,25(OH)2D3 did not show additive inhibitory effects on spike protein-potentiated platelet aggregation and the phosphorylation of β3, c-Src and Syk. Thus, our data suggest that 1,25(OH)2D3 attenuates platelet aggregation potentiated by spike protein via downregulating integrin αIIbβ3 outside-in signaling.

Enhancement of NETosis by ACE2-cross-reactive anti-SARS-CoV-2 RBD antibodies in patients with COVID-19.

High levels of neutrophil extracellular trap (NET) formation or NETosis and autoantibodies are related to poor prognosis and disease severity of COVID-19 patients. Human angiotensin-converting enzyme 2 (ACE2) cross-reactive anti-severe acute respiratory syndrome coronavirus 2 spike protein receptor-binding domain (SARS-CoV-2 RBD) antibodies (CR Abs) have been reported as one of the sources of anti-ACE2 autoantibodies. However, the pathological implications of CR Abs in NET formation remain unknown. In this study, we first assessed the presence of CR Abs in the sera of COVID-19 patients with different severity by serological analysis. Sera and purified IgG from CR Abs positive COVID-19 patients as well as a mouse monoclonal Ab (mAb 127) that can recognize both ACE2 and the RBD were tested for their influence on NETosis and the possible mechanisms involved were studied. An association between CR Abs levels and the severity of COVID-19 in 120 patients was found. The CR Abs-positive sera and IgG from severe COVID-19 patients and mAb 127 significantly activated human leukocytes and triggered NETosis, in the presence of RBD. This NETosis, triggered by the coexistence of CR Abs and RBD, activated thrombus-related cells but was abolished when the interaction between CR Abs and ACE2 or Fc receptors was disrupted. We also revealed that CR Abs-induced NETosis was suppressed in the presence of recombinant ACE2 or the Src family kinase inhibitor, dasatinib. Furthermore, we found that COVID-19 vaccination not only reduced COVID-19 severity but also prevented the production of CR Abs after SARS-CoV-2 infection. Our findings provide possible pathogenic effects of CR Abs in exacerbating COVID-19 by enhancing NETosis, highlighting ACE2 and dasatinib as potential treatments, and supporting the benefit of vaccination in reducing disease severity and CR Abs production in COVID-19 patients.

High throughput screening identifies dasatinib as synergistic with trametinib in low grade serous ovarian carcinoma

BackgroundLow grade serous ovarian carcinoma (LGSOC) is a distinct histotype of ovarian cancer characterised high levels of intrinsic chemoresistance, highlighting the urgent need for new treatments. High throughput screening in clinically-informative cell-based models represents an attractive strategy for identifying candidate treatment options for prioritisation in clinical studies. MethodsWe performed a high throughput drug screen of 1610 agents across a panel of 6 LGSOC cell lines (3 RAS/RAF-mutant, 3 RAS/RAF-wildtype) to identify novel candidate therapeutic approaches. Validation comprised dose-response analysis across 9 LGSOC models and 5 high grade serous comparator lines. Results16 hits of 1610 screened compounds were prioritised for validation based on >50% reduction in nuclei counts in over half of screened cell lines at 1000 nM concentration. 11 compounds passed validation, and the four agents of greatest interest (dasatinib, tyrosine kinase inhibitor; disulfiram, aldehyde dehydrogenase inhibitor; carfilzomib, proteasome inhibitor; romidepsin, histone deacetylase inhibitor) underwent synergy profiling with the recently approved MEK inhibitor trametinib. Disulfiram demonstrated excellent selectivity for LGSOC versus high grade serous ovarian carcinoma comparator lines (P = 0.003 for IC50 comparison), while the tyrosine kinase inhibitor dasatinib demonstrated favourable synergy with trametinib across multiple LGSOC models (maximum zero interaction potency synergy score 46.9). The novel, highly selective Src family kinase (SFK) inhibitor NXP900 demonstrated a similar trametinib synergy profile to dasatinib, suggesting that SFK inhibition is the likely driver of synergy. ConclusionDasatinib and other SFK inhibitors represent novel candidate treatments for LGSOC and demonstrate synergy with trametinib. Disulfiram represents an additional treatment strategy worthy of investigation.

Abstract 615: NXP900, a novel YES1/SRC kinase inhibitor in phase 1, demonstrates potent inhibition of proliferation in cell lines resistant to ALK and EGFR inhibitors

Abstract Background: NXP900 (eCF506) is a novel potent and selective SRC family kinase (SFK) inhibitor, (IC50 of 0.47 nM against YES1). NXP900 locks its target into its native “closed” conformation (type 1.5), thereby inhibiting both kinase activity and complex formation with protein partners (Temps et al. Cancer Res. 2021, 81, 5438). In contrast, multi-kinase inhibitors, including dasatinib and bosutinib, block SRC in the active “open” conformation (type 1) promoting the association of SFK and signaling partners via allosteric facilitation (Higuchi et al. Cell Rep. 2021, 34, 108876). Activation of SFK suggests that NXP900 may have therapeutic potential in cancers with acquired resistance to EGFR and ALK inhibitors. Methods: Cell lines: Alectinib sensitive (NCI-H2228, ATCC) and osimertinib sensitive (PC9, RIKEN). Alectinib resistant (H2228-ALR1, H2228-ALR2, H2228-ALR3, H2228-ALR4) and osimertinib resistant (PC9-OR1, PC9-OR3) cell lines were generated by treatment of NCI-H2228 or PC9 with increasing concentrations of, respectively, alectinib or osimertinib. Cell proliferation assay: Intracellular ATP (Oncolines B.V.); cells were treated with inhibitors for 120 hours. Reverse Phase Protein Array (RPPA): Protein extracts were prepared from cell lines at sequential timepoints following treatment with NXP900 or a combination of NXP900 and osimertinib. Extracts were printed as a concentration series onto nitrocellulose coated slides across multiple sub-arrays using an Aushon2470 arrayer, each sub-array was addressed with individual mono-specific antibodies to quantify the abundance of SRC, EGFR and other canonical cancer signaling pathway phosphorylation events. Results: NXP900 single agent potently inhibited cell proliferation of ALK sensitive (GI50=83nM) and all ALK resistant cell lines (GI50=5.8-16nM). GI50 for EGFR sensitive and EGFR resistant cells were 605 nM and 826-4665 nM, respectively. In combination with a fixed concentration of osimertinib (160nM), NXP900 potently reversed osimertinib resistance in both EGFR resistant cell lines (GI50= 43-121 nM). Conclusions: Despite high response rates to osimertinib and alectinib, acquired resistance almost universally arises. Here we demonstrate that NXP900 can potently inhibit cell proliferation of ALK resistant cell lines as a single agent and EGFR resistant cell lines in combination with osimertinib. Activation of SFK and YAP1 has been shown to be important in the development of resistance to ALK and EGFR treatment. We have previously demonstrated that NXP900 potently inhibits YAP1 nuclear localization and induces tumor regressions in squamous models in vivo providing additional proof of concept for targeting solid tumors with YES1/SRC and Hippo pathway alterations. A FIH, Phase1 dose escalation study for NXP900 has been initiated. Citation Format: Neil O. Carragher, Enrique Poradosu, Ben King, Alison F. Munro, John C. Dawson, Asier Unciti-Broceta. NXP900, a novel YES1/SRC kinase inhibitor in phase 1, demonstrates potent inhibition of proliferation in cell lines resistant to ALK and EGFR inhibitors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 615.

CCL19-Positive Lymph Node Stromal Cells Governthe Onset of Inflammatory Arthritis via Tropomyosin Receptor Kinase.

The study objective was to assess the role of CCL19+ lymph node stromal cells of the joint-draining popliteal lymph node (pLN) for the development of arthritis. CCL19+ lymph node stromal cells were spatiotemporally depleted for five days in the pLN before the onset of collagen-induced arthritis (CIA) using Ccl19-Cre × iDTR mice. In addition, therapeutic treatment with recombinant CCL19-immunoglobulin G (IgG), locally injected in the footpad, was used to confirm the results. RNA sequencing of lymph node stromal cells combined with T cell coculture assays using tropomyosin receptor kinase (Trk) family inhibitors together with in vivo local pLN small interfering RNA (siRNA) treatments were used to elucidate the pathway by which CCL19+ lymph node stromal cells initiate the onset of arthritis. Spatiotemporal depletion of CCL19+ lymph node stromal cells prevented disease onset in CIA mice. These inhibitory effects could be mimicked by local CCL19-IgG treatment. The messenger RNA sequencing analyses showed that CCL19+ lymph node stromal cells down-regulated the expression of the tropomyosin receptor kinase A (TrkA) just before disease onset. Blocking TrkA in lymph node stromal cells led to increased T cell proliferation in in vitro coculture assays. Similar effects were observed with the pan-Trk inhibitor larotrectinib in cocultures of lymph node stromal cells of patients with rheumatoid arthritis and T cells. Finally, local pLN treatment with TrkA inhibitor and TrkA siRNA led to exacerbated arthritis scores. CCL19+ lymph node stromal cells are crucially involved in the development of inflammatory arthritis. Therefore, targeting of CCL19+ lymph node stromal cells via TRK could provide a tool to prevent arthritis.

Moving Beyond Boundaries: Utilization of Longitudinal Exposure-Response Model for Bounded Outcome Score to Inform Decision Making in the Accelerated Drug Development Paradigm.

As drug development scientists strive to accelerate availability of therapies for patients, model-informed drug development (MIDD) plays an important role in contextualizing existing information and facilitating decision making. This paper describes an example of MIDD, where modeling and simulation informed decision making in the circumstance of a combined phase 2b and single pivotal study for ritlecitinib (JAK3/TEC family kinases inhibitor). Longitudinal exposure-response (ER) modeling was conducted to describe ritlecitinib efficacy in alopecia areata patients. The Severity of Alopecia Tool (SALT) score (a continuous bounded outcome [CBO] score [0-100]) was used as the efficacy response. The average concentration during the time interval between two adjacent SALT scores was used as the exposure metric driving efficacy. The developed model well described the longitudinal SALT profile of ritlecitinib as well as the frequency of boundary data. The CBO model indicated tested doses in the phase 2b/3 clinical trial are in the ascending region of ER and contextualized a loading dose effect that impacted onset of efficacy without long-term benefit. It also identified disease severity as the only covariate impacting efficacy. The model-based simulation further informed impact of treatment interruption on the loss of efficacy in the absence of a dedicated treatment withdrawal study. Results indicated temporary treatment interruption ≤ 6 weeks is not expected to result in significant loss of efficacy. The CBO modeling approach and simulation supported the single pivotal trial strategy and guided dose selection in the accelerated drug development program of ritlecitinib, which can be applied to many indications where efficacy is measured on a bounded scale.

OP09 Oral ritlecitinib and brepocitinib in patients with moderate to severe active Crohn’s Disease: Data from the PIZZICATO umbrella study

Abstract Background Oral ritlecitinib (RIT; JAK3/TEC family kinase inhibitor) and brepocitinib (BRE; TYK2/JAK1 inhibitor) are being assessed in a 64-week (wk) phase 2a randomised, double-blind, induction-maintenance, umbrella study (PIZZICATO; NCT02958865) in participants (pts) with moderate-to-severe active Crohn’s disease (CD) with inadequate, loss of response or intolerance of corticosteroids, immunosuppressants or biologics. We report the efficacy and safety results from the 12-wk induction period. Methods Pts 18-75 years old with endoscopic confirmation of active CD with Simple Endoscopic Score for CD (SES-CD) ≥7/≥4 for isolated ileal disease, and average daily liquid/soft stool frequency (SF) ≥2.5 or daily abdominal pain (AP) ≥2.0 were included. Pts were randomised to RIT 200 mg once daily (QD) for 8 wks then 50 mg QD for 4 wks and matching placebo (PBO) in a 2:1 ratio or BRE 60 mg QD for 12 wks and matching PBO in a 2:1 ratio. Pts continued in their respective arms with open-label RIT 50 mg or BRE 30 mg QD for 52 wks. PBO arms were combined for analysis. Pts achieving SES-CD 50 (≥50% reduction in SES-CD from baseline [BL]; primary endpoint Wk 12), Clinical Disease Activity Index (CDAI) remission (CDAI&amp;lt;150) and CDAI-100 response for pts with BL CDAI≥220, clinical response (≥30% reduction from BL in AP or SF; neither worse than BL) and remission (SF≤1.5 and AP≤1; neither worse than BL) were assessed. Safety was also evaluated. Results A total of 244 pts were randomised and received treatment in the induction period with BL mean age of 34.6-36.5 years, median SES-CD 11-14, and prior biologics experience 69-76% across groups. The proportion of pts achieving SES-CD 50 was significantly higher at Wk 12 with RIT 200/50 mg QD and BRE 60 mg vs PBO (change from PBO: RIT 14.3% [90% CI, 4.0, 24.5], BRE 21.4% [10.0, 32.9]; Table). Statistical significance vs PBO was observed for RIT at Wks 8 and 12 and BRE at Wk 12 for CDAI remission, CDAI-100, clinical response and remission by SF or AP. Most treatment emergent adverse events (TEAEs) in both groups were mild or moderate. Herpes infections occurred in 1 pt in each group and serious infections in 1 pt in RIT and 2 in BRE. No deaths or malignancies occurred. No events of thromboembolism or MACE occurred for RIT. One pt on BRE had a TEAE of pulmonary embolism. There were no clinically significant observations for labs. Conclusion Both RIT and BRE met the primary endpoint in the induction period with significant clinical improvement vs PBO in pts with active CD. Other meaningful efficacy endpoints had similar results to the primary endpoint for both therapies. RIT and BRE had an acceptable safety and tolerability profile that was consistent with previous studies.