Human IgG1 Monoclonal Antibody Research Articles

Sintilimab Plus Chemotherapy for Unresectable Gastric or Gastroesophageal Junction Cancer

Gastric and gastroesophageal junction cancers are diagnosed in more than 1 million people worldwide annually, and few effective treatments are available. Sintilimab, a recombinant human IgG4 monoclonal antibody that binds to programmed cell death 1 (PD-1), in combination with chemotherapy, has demonstrated promising efficacy. To compare overall survival of patients with unresectable locally advanced or metastatic gastric or gastroesophageal junction cancers who were treated with sintilimab with chemotherapy vs placebo with chemotherapy. Also compared were a subset of patients with a PD ligand 1 (PD-L1) combined positive score (CPS) of 5 or more (range, 1-100). Randomized, double-blind, placebo-controlled, phase 3 clinical trial conducted at 62 hospitals in China that enrolled 650 patients with unresectable locally advanced or metastatic gastric or gastroesophageal junction adenocarcinoma between January 3, 2019, and August 5, 2020. Final follow-up occurred on June 20, 2021. Patients were randomized 1:1 to either sintilimab (n = 327) or placebo (n = 323) combined with capecitabine and oxaliplatin (the XELOX regimen) every 3 weeks for a maximum of 6 cycles. Maintenance therapy with sintilimab or placebo plus capecitabine continued for up to 2 years. The primary end point was overall survival time from randomization. Of the 650 patients (mean age, 59 years; 483 [74.3%] men), 327 were randomized to sintilimab plus chemotherapy and 323 to placebo plus chemotherapy. Among the randomized patients, 397 (61.1%) had tumors with a PD-L1 CPS of 5 or more; 563 (86.6%) discontinued study treatment and 388 (59.7%) died; 1 patient (<0.1%) was lost to follow-up. Among all randomized patients, sintilimab improved overall survival compared with placebo (median, 15.2 vs 12.3 months; stratified hazard ratio [HR], 0.77 [95% CI, 0.63-0.94]; P = .009). Among patients with a CPS of 5 or more, sintilimab improved overall survival compared with placebo (median, 18.4 vs 12.9 months; HR, 0.66 [95% CI, 0.50-0.86]; P = .002). The most common grade 3 or higher treatment-related adverse events were decreased platelet count (sintilimab, 24.7% vs placebo, 21.3%), decreased neutrophil count (sintilimab, 20.1% vs placebo, 18.8%), and anemia (sintilimab, 12.5% vs placebo, 8.8%). Among patients with unresectable locally advanced or metastatic gastric and gastroesophageal junction adenocarcinoma treated with first-line chemotherapy, sintilimab significantly improved overall survival for all patients and for patients with a CPS of 5 or more compared with placebo. ClinicalTrials.gov Identifier: NCT03745170.

Exposure‐response modeling to describe the change in brain amyloid following lecanemab administration in patients with early Alzheimer’s disease

AbstractBackgroundLecanemab is a humanized IgG1 monoclonal antibody that binds with high affinity to Aβ soluble protofibrils. Lecanemab has been tested as a disease‐modifying treatment for early Alzheimer’s disease in two clinical studies (NCT01767311 and CLARITY‐AD, NCT03887455). As part of these studies, amyloid PET scans were collected in a subset of patients, demonstrating that lecanemab leads to pronounced reduction in brain amyloid.MethodA model describing the relationship between serum lecanemab exposure and brain amyloid reduction from baseline was developed using data pooled from Phase 2 and 3 studies. Individual serum lecanemab exposure was estimated using a population PK model and correlated with amyloid PET using an indirect response model, with a lecanemab‐dependent increase in the degradation rate of amyloid, introduced as linear function. The model was parametrized in terms of baseline amyloid load, elimination rate constant for amyloid removal (Kout) and exposure effect (DESLP). Inter‐subject variability was estimated for each of the model parameters. Covariates were included in the model using a forward‐inclusion (p&lt;0.01) /backwards‐elimination (p&lt;0.001) approach.ResultA total of 4129 observations from 1088 subjects were included in the dataset. The model estimate of Kout was 0.0496 yr−1 (95% confidence interval: 0.0206, 0.0827), suggesting a re‐accumulation half‐life of brain amyloid of ∼14 years. APOE4 carrier status (homozygous and heterozygous together) was a statistically significant predictor of baseline amyloid (APOE4 noncarriers: 65 CL; APOE4 carriers: 83 CL). Age was a significant covariate on DESLP, with older patients removing amyloid at a faster rate than younger patients. None of the other covariates explored, including presence of antidrug antibodies or baseline MMSE score, had a statistically significant effect on any model parameter.ConclusionAn exposure‐response model has been developed that describes the change in brain amyloid over time during treatment with lecanemab and after stopping lecanemab treatment. This model provides additional insights into factors that may drive differences in the rate of brain amyloid removal between patients.

Lecanemab: Amyloid Reduction and Evidence of Downstream Biomarker Modification

AbstractBackgroundLecanemab is a humanized IgG1 monoclonal antibody that targets soluble aggregated Aβ species (protofibrils) which has demonstrated robust brain fibrillar amyloid reduction and slowing of clinical decline in a Phase 3 Study in early AD (Study 301). The objective of this analysis is to report biomarker results from Study 301.MethodsStudy 301 was a double‐blind, randomized, placebo‐controlled study of 1875 patients with early AD randomized to 10 mg/kg IV lecanemab or placebo for 18 months of treatment. Plasma, CSF, and imaging biomarkers of amyloid, tau, neurodegeneration, and gliosis were assessed.ResultsLecanemab met all primary and key secondary clinical endpoints with a high degree of statistical significance. Lecanemab improved markers of amyloid with reduction of brain amyloid by PET in as early as 3 months and improvement in CSF Aß42 and plasma Aß42/40. Biomarkers of tau showed improvement in CSF and plasma p‐tau181, and slowing of tau accumulation relative to placebo in the medial temporal regions by tau PET. For biomarkers of neurodegeneration and gliosis, there was improvement in CSF t‐tau, CSF neurogranin, and plasma GFAP. There were no significant differences in CSF or plasma Nf‐L between lecanemab and placebo. Volumetric MRI results were inconsistent, with reduced hippocampal atrophy on lecanemab, but greater cortical volume loss relative to placebo, possibly “pseudoatrophy” related to amyloid mobilization.ConclusionsLecanemab treatment resulted in significant reduction in amyloid plaques and a slowing of clinical decline. Improvements in biomarkers of amyloid, tau, neurodegeneration, and gliosis provide a biological basis for the treatment effects consistent with disease modification.

P143: New therapies for Alzheimer’s dementia and its implications on healthcare system: are we ready?

Objective:The amyloid hypothesis suggests that errors in production, accumulation, or disposal of beta-amyloid are the primary causes of Alzheimer's disease (AD). Since this was hypothesized, there has been significant effort in developing treatments that prevent the build-up of amyloid beta (Aβ) plaques in the brain. A disease modifying therapy (DMT) changes the clinical progression of AD by interfering in its pathophysiological mechanisms.The aim of this article is to review the current literature regarding the role of new DMTs for Alzheimer’s dementia and assess the preparedness of health care systems to implement these treatment options.Methods:Review of the most recent literature regarding the role of new DMTs for Alzheimer’s dementia and the challenges faced by the health care system to implement these treatment options. The research was carried out through the PubMed and UptoDate databases, using the terms “amyloid hypothesis”, “Alzheimer”, “disease modifying treatments” and “dementia”.Results:Research has been focusing on developing monoclonal antibodies as potential DMTs that target Aβ. Aducanumab, a human antibody, or immunotherapy, is the only disease-modifying medication currently approved to treat AD. It targets the Aβ protein and helps to reduce amyloid plaques and is currently the only FDA approved medication to slow the progression of AD. Lecanemab, a humanized IgG1 monoclonal antibody, binds to Aβ soluble protofibrils with high affinity. Even though there is considerable optimism about its potential, lecanemab will probably be more useful to patients on early stages of the disease.Conclusion:DMTs administration obeys to certain needs such as a vacancy in Day Hospital for infusion and regular monitorization and for lumbar punction. It demands a complex network involving general practitioner, neurologist, psychiatrist, psychologist, and social services. It also involves a genetic study and complementary diagnosis exams such as PET (Positron emission tomography) scans and MRIs (Magnetic resonance imaging), which are expensive. There is an emerging need to develop enhanced and safer treatments.

Management of Moderate to Severe Plaque Psoriasis with Brodalumab in Daily Practice: Real-World Evidence from the LIBERO Study in the Czech Republic.

Psoriasis is a chronic, immune-mediated inflammatory skin disease. Despite the availability of several therapies, many patients affected by this disease remain untreated, do not have adequate response, or suffer from treatment-related toxic effects. It has been shown that the interleukin (IL)-17 pathway plays a key role in the immunopathogenesis of psoriasis. Brodalumab, the first human monoclonal IgG2 antibody that selectively binds to subunitA of the human IL-17 receptor, blocking interactions with a number of cytokines of the IL-17 family, has confirmed fast onset of action, high complete clearance rates, and sustained efficacy. Nevertheless, there is only a limited amount of published real-world evidence (RWE) data. This was an open-label, multicenter, real-world, prospective, non-interventional, non-controlled (single-arm) observational study (LIBERO-CZ) assessing the management of moderate to severe psoriasis with brodalumab in daily practice for up to 52weeks of treatment. Fifty-four patients (70.4% male, mean age 46.9 ± 13.4years, weight 95.6 ± 22.7kg, disease duration 18.6 ± 12.7years) were enrolled and included in the final analysis. Forty-nine of the patients completed the study and five discontinued prematurely; 51.8% of all the enrolled patients were biologic-naïve. At baseline, 28% patients were classified as severe (psoriasis area severity index (PASI) ≥ 20). Overall, the mean PASI decreased by 15.6 from 16.1 (± 5.0) at baseline to 0.5 (± 1.2) at the last visit. The primary endpoint of an absolute PASI ≤ 3 at week12 (as observed analysis) was achieved by 95.9% of patients. The static Physician's Global Assessment (sPGA) success (defined as clear = 0 and almost clear = 1) at week52 was achieved by 92.1% of patients. PASI75, PASI90, and PASI100 were achieved by 98.0%, 87.8%, and 75.5% of patients, respectively, after approximately 52weeks of treatment. The study also recorded very positive results concerning patient-reported outcomes. LIBERO-CZ confirms the fast onset and high clearance rates of brodalumab in real life in both biologic-naïve and biologic-experienced patients.

Alternative Pathway Masp-3 Inhibitor OMS906 Effectively and Potently Inhibits Complement-Mediated Hemolysis in Preclinical Models Mechanistically Similar to Paroxysmal Nocturnal Hemoglobinuria

Introduction: Mannan-binding lectin-associated serine protease-3 (MASP-3) activates pro-complement Factor D (CFD) to form mature CFD, a rate-limiting enzyme in the alternative pathway (AP) of the complement system. CFD controls cleavage of complement Factor B (CFB) to form AP C3 convertase, which drives an amplification loop of protease complexes that activates both C3b-mediated opsonization and the terminal pathway. OMS906 is a humanized IgG4 monoclonal antibody (mAb) that binds to and inhibits MASP-3, thereby blocking maturation of CFD and downstream AP activity. Data from mice and monkeys demonstrated that OMS906 is highly selective and effectively inhibits AP activity. MASP-3 inhibition could provide therapeutic benefit in a variety of AP-mediated diseases, such as paroxysmal nocturnal hemoglobinuria (PNH). In PNH, a rare and life-threatening disorder, red blood cells (RBCs) lacking CD59 and CD55 regulatory surface proteins are targeted for rapid clearance via intravascular hemolysis and extravascular hemolysis, due to AP dysregulation. Clinical efficacy of OMS906 in a study of patients with PNH has been reported. To provide mechanistic support, we conducted in vitro and in vivo studies using preclinical models of complement-mediated hemolysis that have mechanistic overlap with PNH. Methods: In vitro potency of OMS906 was assessed using RBCs deficient in CD55 and CD59 to mimic the physiological effect of PNH. Healthy human donor RBCs were treated with inhibitory CD55 and CD59 antibodies, then incubated under AP assay conditions with human serum (diluted to 50%) containing OMS906, anti-C5 IgG4 mAb, or an isotype mAb control. The potency of OMS906, expressed as the half-maximal inhibitory concentration (IC 50), was assessed based on prevention of hemolysis of the PNH-like RBCs in vitro. Lysis was quantified by measuring hemoglobin released into sample supernatants using spectrophotometric absorbance. The in vivo effect of OMS906 on survival of murine RBCs prone to rapid clearance was assessed using RBCs from Crry -/- mice, which lack a rodent-specific complement regulatory protein that blocks AP activation. C57BL/6J male mice were intravenously injected with fluorescent labelled Crry -/- RBCs and received OMS906 or isotype mAb control via subcutaneous injection, or anti-CFB mAb via intraperitoneal injection. Blood samples were taken daily until Day 14 and the remaining number of Crry -/- RBCs measured by flow cytometry. Results: In vitro, OMS906 inhibited terminal cell lysis in human PNH-like RBCs more potently than a C5 inhibitor. Comparison of representative drug concentration-response showed that the average functional potency was 58-fold greater with OMS906 (IC 50: 0.8 μg/mL; 3 experiments; 12 total RBC donors) than with anti-C5 mAb (IC 50: 46.2 μg/mL; 2 experiments; 4 total RBC donors). In addition, the maximal extent to which lysis was inhibited was consistently greater with OMS906 than with anti-C5 mAb. In vivo, the rate of decline in number of Crry -/- RBCs was significantly slowed in mice treated with OMS906, in contrast to the rapid loss observed in isotype mAb control-treated mice ( Figure). OMS906 recipients showed a rate of Crry -/- RBC survival similar to the anti-CFB mAb group. Conclusion: OMS906 inhibited RBC lysis more potently than a C5 inhibitor, providing evidence that MASP-3 inhibition blocks downstream terminal activity and thus intravascular hemolysis. In addition, OMS906 improved survival of Crry -/- RBCs comparably to a CFB inhibitor, indicating that MASP-3 inhibition prevents the AP-mediated destruction of RBCs predictive of extravascular hemolysis. OMS906 is currently in clinical development for the treatment of PNH.

Safety and Preliminary Efficacy of Sabestomig (AZD7789), an Anti-PD-1 and Anti-TIM-3 Bispecific Antibody, in Patients with Relapsed or Refractory Classical Hodgkin Lymphoma Previously Treated with Anti-PD-(L)1 Therapy

Background Immunotherapies targeting the PD-1/PD-L1 pathway have been shown to induce high response rates in patients with relapsed/refractory (r/r) classical Hodgkin lymphoma (cHL). However, most responses are partial and not durable. T cell immunoglobulin and mucin domain-containing protein-3 (TIM-3) is implicated as a resistance mechanism following anti-PD-1 therapy, and increased TIM-3 expression has been observed on T cells of patients with cHL post anti-PD-1 therapy. Therefore, we hypothesized that dual targeting of PD-1 and TIM-3 may reinvigorate immune responses and lead to more durable antitumor activity. Sabestomig is a monovalent, bispecific, humanized IgG1 monoclonal antibody that binds PD-1 and a unique epitope in the TIM-3 IgV domain without blocking phosphatidylserine binding, eliciting differential functionality. In preclinical mouse models, sabestomig was more effective at inhibiting growth of solid tumors than treatment targeting only PD-1, and sequential sabestomig after anti-PD-1 therapy increased antitumor responses. Here we report preliminary data from the ongoing dose escalation portion of a Phase I/II, open-label, multicenter study to assess the safety and preliminary efficacy of sabestomig in patients with r/r cHL (NCT05216835). Methods Eligible patients are aged ≥16 years with r/r cHL, an Eastern Cooperative Oncology Group performance status 0-1, at least one positron emission tomography-avid measurable lesion according to modified Lugano Criteria, and exposure to at least 2 prior lines of systemic therapy including a minimum of 3 cycles of an anti-PD-(L)1-based therapy. Sabestomig is intravenously infused over 1 hour following pretreatment with diphenhydramine and acetaminophen every 3 weeks, with planned doses ranging from 2 to 2000 mg across 8 cohorts (A1-A8); cohorts A1 to A4 (2, 7, 22.5 or 75 mg) follow an accelerated titration design with a single patient treated at each dose level, while cohorts A5 to A8 (225-2000 mg) follow a modified toxicity probability interval-2 algorithm. The primary endpoint of the dose escalation part of the study is safety, including dose-limiting toxicities (DLTs). Secondary endpoints include efficacy, pharmacokinetics, and immunogenicity. Data cutoffs were May 17, 2023 for safety and June 20, 2023 for efficacy. Results As of May 17, 2023, 14 patients were treated across the first 6 cohorts (A1-A6; 2-750 mg). They were predominantly male (64.3%) with Stage IV disease (85.7%) and a median age of 41.5 years (range, 25-77). Patients received a median of 6 prior lines of therapy (range, 3-13). Baseline disease characteristics are summarized in Table 1. Four patients received sabestomig 2-75 mg in cohorts A1-A4 (n=1 each), 5 patients received 225 mg in cohort A5, and 5 patients received 750 mg in cohort A6. Median duration of exposure to sabestomig was 8.9 weeks (range, 3.0-34.3) with a median of 3 cycles received (range 1-12). Sabestomig was well tolerated with no Grade ≥3 treatment-related adverse events (AEs) (Table 2). One Grade ≥3 AE occurred, which was fatal (sepsis secondary to gastric ulcer rupture, not related to sabestomig but deemed a DLT by the safety review committee). No immune-mediated AEs were reported, and no AEs led to treatment discontinuation. At the safety data cutoff, treatment was ongoing for 6 patients (42.9%). As of June 20, 2023, 11 patients had their first disease assessment and 4/11 had an objective response based on modified Lugano Criteria: 1 patient in cohort A3 (22.5 mg, a partial response [PR]) and all 3 patients who had their first disease assessment in cohort A6 (750 mg, 2 CRs and 1 PR). Two of these 4 responders (both in cohort A6) had experienced a best overall response of progressive disease during prior anti-PD-1 therapy; the other two initially had a response (1 CR [cohort A6] and 1 PR [cohort A3]) but subsequently progressed on anti-PD-1 therapy. Sustained PD-1 receptor occupancy (≥90%) was observed in peripheral blood at doses ≥225 mg. Conclusions Sabestomig was well tolerated with a manageable safety profile. Early efficacy data at 750 mg is encouraging with objective responses in 3/3 patients who had their first disease assessment, including those who were anti-PD-1 refractory or who relapsed on treatment. Updated data will be presented from ongoing and subsequent patients treated during dose escalation with doses of up to 2000 mg.

Axatilimab Ameliorates Inflammation and Fibrosis By Targeting Macrophages in a Preclinical Model of Chronic GVHD

Introduction: Chronic graft-versus-host disease (cGVHD) is an immune-mediated serious and life-threatening complication after allogeneic hematopoietic stem cell transplantation, occurring in 30%-70% of patients. The pathophysiology of cGVHD may involve inflammation, cell-mediated immunity, humoral immunity, and fibrosis. Axatilimab is a high-affinity humanized IgG4 (kappa light chain) monoclonal antibody targeting colony-stimulating factor 1 receptor (CSF-1R) that is under investigation for the treatment of cGVHD. CSF-1R is a member of the receptor protein tyrosine kinase family of growth factor receptors and is expressed on monocyte precursors, monocytes, and macrophages. Signaling by colony-stimulating factor 1 (CSF-1) or interleukin-34 (IL-34) through CSF-1R has been shown to be the primary regulatory pathway for determining development and differentiation of the mononuclear phagocytic cell lineage. Recent work has established a role for monocyte-derived macrophages as the pathogenic population of cells that establish the fibrotic niche and drive the fibrotic process. Upon entry of monocytes into tissues, the tissue microenvironment regulates their differentiation, resulting in a heterogeneous pool of cells ranging from pro-inflammatory (often referred to as M1 macrophages) to immune suppressive/wound healing (M2 macrophages). An imbalance in the number and activity of these macrophage populations is believed to result in the excess production of fibrotic growth factors, such as transforming growth factor-β and platelet-derived growth factor, leading to uncontrolled fibroblast activation and subsequent fibrosis. Blocking CSF-1R signaling with axatilimab is expected to reduce the circulating levels of pathogenic monocyte-derived macrophage precursors and inhibit their activation in tissues, thereby providing an opportunity to therapeutically intervene in diseases such as cGVHD. The results described herein support this assertion by demonstrating the direct impact of axatilimab exposure to skewing differentiating monocytes away from a pro-inflammatory and pro-fibrotic phenotype. Methods: Primary human monocytes were differentiated in the presence or absence of ascending doses of axatilimab (0.07-7 μM) into distinct phenotypes: activated (M0), pro-inflammatory (M1-like), and suppressive (M2-like) macrophages. Supernatants and cell pellets were then assessed for secreted protein (Luminex Corporation) and gene expression (NanoString Technologies) profiles, respectively. Data were analyzed in R (version 4.1.1). Results: Gene expression profiles of pro-inflammatory cytokines and chemokines (eg, IL-1β, chemokine CC motif ligand 2 [CCL2], CCL7, CCL24, and CCL22) from primary differentiated macrophage subsets were dramatically reduced in the presence of ascending concentrations of axatilimab. Further, macrophages exposed to axatilimab while differentiated under pro-inflammatory conditions showed increased levels of c-MYC expression compared with control cultures. c-MYC is a transcription factor associated with suppressive M2-like macrophages, which suggests that axatilimab interferes with pro-inflammatory macrophage differentiation. Consistent with this, expression of M2-associated cytokines, including IL-10, IL-5, and IL-4, was enhanced in axatilimab-treated macrophage cultures. Conclusions: Blocking CSF-1R signaling in primary, differentiated macrophages dramatically alters the secretomes and gene expression profiles of these cells. Macrophages are key inducers of fibroblast growth factors, which in turn promote fibrotic disease. These data confirm that production of inflammatory and pro-fibrotic factors by pro-inflammatory macrophages is inhibited in the presence of axatilimab, thereby supporting the notion that axatilimab provides a unique opportunity to therapeutically intervene or prevent fibrosis in cGVHD.

Sabatolimab in Combination with Hypomethylating Agents (HMAs) Was Safe in Patients (Pts) with Intermediate-, High-, or Very-High-Risk Myelodysplastic Syndrome (MDS)

CONCLUSIONS Complete remission (CR) with standard-of-care HMAs in pts with intermediate-, high-, and very-high-risk MDS is usually infrequent and transient, and prognosis remains poor for these pts, who have limited second-line treatment options. Sabatolimab is a high-affinity, humanized anti-TIM3 IgG4 monoclonal antibody that blocks the TIM3 immune checkpoint receptor, which is preferentially expressed on leukemic stem cells and blasts and plays a key role in regulating adaptive and innate immune responses. In a phase Ib study, sabatolimab in combination with intravenous (IV) HMA was safe and well tolerated in pts with high-risk MDS with overall response rates of 61.1% and 57.9% with decitabine and azacitidine, respectively. We present an interim analysis of the STIMULUS-MDS US trial (NCT04878432) to assess the safety of sabatolimab in combination with not only parenteral but also oral HMAs in pts with intermediate-, high-, and very-high-risk MDS. This is a multicenter, phase II, open-label, single-arm study of sabatolimab in combination with HMAs. Adults aged ≥18 years with intermediate-, high-, or very-high-risk MDS per Revised International Prognostic Scoring System criteria who were not previously treated with HMAs were eligible. Pts received an HMA of investigator's choice (decitabine/cedazuridine 35 mg/100 mg oral days 1-5, decitabine 20 mg/m 2 IV days 1-5, or azacitidine 75 mg/m 2 IV or subcutaneous [SC] days 1-7 or days 1-5 plus days 8 and 9) with sabatolimab 800 mg IV every 4 weeks starting at day 8 or any day between days 5 to 8. The primary objective of this study was to assess the safety of sabatolimab in combination with oral, IV, and SC HMAs. Secondary objectives included assessing the efficacy of the combination. The study includes a core phase for up to 12 months, an extension phase for efficacy and survival status up to 12 months after the core phase, and a post-treatment safety follow-up for 30 days following the last dose of HMA or 150 days following the last dose of sabatolimab, whichever is later. This interim analysis included 33 pts with intermediate-, high-, and very-high-risk MDS at the data cutoff of 6 months after cycle 1 day 1 of treatment with sabatolimab and an HMA. The median age was 69 years (range, 39-86). At data cutoff, 8 pts were in ongoing treatment, and 25 pts had discontinued the core phase. Reasons for discontinuation included new therapy for study indication (n=6), physician decision (n=6), pt decision (n=5), progressive disease (n=4), unsatisfactory therapeutic effect (n=2), adverse event (AE) (n=1), and death (n=1). Of those who discontinued study treatment, 6 pts were in ongoing evaluation in the extension phase and 3 pts were in ongoing evaluation in the post-treatment follow-up phase. The median duration (range) of exposure was 3.9 (0.92-5.91) months for sabatolimab and 4.2 (1.05-6.08) months for HMAs. Among 33 pts evaluable for safety, most experienced all-grade and grade ≥3 AEs, AEs requiring additional therapy, and serious AEs (Figure). However, the most frequent (≥10%) grade ≥3 AEs were expected hematologic AEs, including febrile neutropenia (42.4%), anemia (39.4%), neutrophil count decrease (39.4%), and platelet count decrease (36.4%). Nonhematologic grades ≥3 AEs occurring in &amp;gt;1 pt included hypertension (18.2%), pneumonia (9.1%), hypoxia (6.1%), and fall (6.1%). Only 1 pt was reported with encephalopathy leading to treatment discontinuation, which was not attributed to study treatment. One pt had a fatal AE for which the cause was not identified but not thought to be related to study treatment by the investigator. The best overall response results in up to 6 months of treatment were available for 22 pts. Marrow CR (mCR) with and without hematologic improvement (HI) was reported in 18.2% and 9.1%, respectively. Partial remission (PR) and stable disease (SD) with HI was reported in 4.5%, each. CR + mCR + PR was 31.8% (95% CI, 13.9%-54.9%), CR + PR + HI was 27.3% (95% CI, 10.7%-50.2%), and CR + mCR + PR + HI was 36.4% (95% CI, 17.2%-59.3%). This interim analysis of the STIMULUS-MDS US study demonstrated that sabatolimab in combination with an oral, IV, or SC HMA was safe and well tolerated, with AEs consistent with previous reports for pts with MDS treated with HMAs. Response rates for the combination are preliminary, and more information will be provided with longer follow-ups.

A Syngeneic Murine Model of Antiphospholipid Syndrome (APS) Recapitulates Aspects of Human APS

Background Antiphospholipid syndrome (APS) is characterized by arterial or venous thrombosis, or recurrent pregnancy loss, in the presence of persistently positive tests for antiphospholipid antibodies (aPL). aPL include lupus anticoagulants (LAC), anti-β2-glycoprotein 1 (β2GPI) and anti-cardiolipin antibodies (aCL). Among them, antibodies directed toward β2GPI have been best characterized and shown in most studies to have a significant association with thrombosis. Most murine models of APS are generated by infusion of either polyclonal IgG isolated from APS patients, or monoclonal IgG directed against human or murine β2GPI. However, one or more of the following limitations may limit their clinical relevance: 1) Unlike chronically elevated autologous aPL in APS patients, cross-species IgG infused into mice circulate for only limited periods of time and may provoke allogeneic responses; 2) Monoclonal human or murine anti-β2GPI IgG, unlike polyclonal aPL from patients, tend to be high affinity, monospecific, and may recognize epitopes different than those recognized by clinical aPL. Hence, we sought to develop a relevant syngeneic murine model of APS that employed polyclonal murine anti-β2GPI IgG that would circulate in mice for extended periods, and not induce allogeneic inflammatory responses. Methods β2GPI-deficient ( apoh -/-) mice were previously developed in our lab on a C57/BL6 background using CRISPR/cas9. IgG isolated from apoh -/- mice immunized with human plasma β2GPI was used as a source of polyclonal murine aPL IgG, while IgG isolated from apoh -/- mice treated with adjuvant alone served as control IgG in all experiments. Wild-type (WT) C57/BL6 mice (two groups of 8 mice each) were injected intravenously with 20 µg of either murine polyclonal aPL or control IgG, and after 72 hours were evaluated for venous thrombosis using the IVC stasis model, with thrombi harvested and measured 48 h after IVC ligation. In parallel studies, we injected mice with aPL or control IgG and evaluated 1) activation of washed platelets, 2) aortic wall gene expression, and 3) levels of circulating neutrophil extracellular traps (NETs) using blood and tissue samples isolated at identical time points as IVC ligation studies (mice in these studies did not undergo IVC ligation). Platelet activation was assessed by measuring the binding of JON/A and expression of platelet P-selectin by flow-cytometry. Total RNA isolated from aortic walls of 3 mice each treated with murine aPL or control IgG was analyzed by RNA sequencing. Results WT C57/BL6 mice that received 20 µg of polyclonal murine aPL sustained plasma anti-β2GPI IgG levels &amp;gt;500 ng/mL for more than 120 h after IgG injection. In the IVC stasis model, six out of eight mice receiving aPL IgG and four out of eight mice receiving control IgG developed thrombi (lack of thrombi in all mice was likely due to bleeding of extensive IVC back branches in C57/BL6 mice). Thrombi weight in aPL-treated mice were significantly larger than those from mice that received control IgG (19.7 ± 1.7 mg vs 13.5 ± 1.0 mg, P = 0.015). Thrombin (0.1 U/ml)-induced platelet activation was significantly greater for platelets isolated from aPL-administered mice compared to those from control mice 72h after IgG injection as determined by binding of JON/A (1246.7 ± 55.3 MFI vs 879 ± 37.9 MFI, P = 0.005) and expression of P-selectin (5729.7 ± 553.9 MFI vs 3777.3 ± 402.5 MFI, P=0.046). Gene enrichment analysis of mRNA from aortas demonstrated significant upregulation of gene pathways related to complement and coagulation cascades, blood coagulation, and oxidoreductase activity in the aPL-treated mice. Individually upregulated genes included C8, C9 fga and fgb. Elevated levels of circulating nucleosomes were also observed in aPL treated mice but did not reach significance due to small numbers. Conclusion These results demonstrate that anti-β2GPI polyclonal aPL raised in apoh-/- mice circulate for extended periods when reinfused into WT mice, enhance thrombosis, induce platelet hyperreactivity, and cause changes in mRNA expression in the vascular wall. Further characterization of anti-β2GPI IgG for LAC activity, anti-PS/PT reactivity and β2GPI domain 1 reactivity is in progress. While all animal models of APS have weaknesses, this syngeneic model provides an additional approach that recapitulates many aspects of vascular inflammation seen in human APS.

Anti-Btla Antibody Tifcemalimab As a Single Agent or in Combination with Toripalimab in Relapsed/Refractory Lymphomas

Background: The B- and T-lymphocyte attenuator (BTLA) is an inhibitory receptor expressed on B, T and NK cells. Using Peripheral Blood Mononuclear Cell (PBMC) derived from cancer patients, co-blockade of the BTLA and PD-1 pathways improved antigen specific T cell response compared to either blockade alone. Tifcemalimab (JS004 or TAB004) is a humanized IgG4 monoclonal antibody with a hinge mutation (S228P) that binds BTLA and blocks its interaction with its ligand Herpesvirus Entry Mediator (HVEM). Tifcemalimab is the first BTLA antibody to enter the clinical development stage. Here, we report the safety and efficacy of tifcemalimab as a single agent or in combination with toripalimab (anti-PD-1) in patients with relapsed/refractory (R/R) lymphoma after long term follow-up. Methods: Eligible patients with R/R lymphoma were enrolled in this open-label, multicenter phase 1 study (NCT04477772). Tifcemalimab was administered as a monotherapy at escalating doses of 1, 3 and 10 mg/kg intravenously Q3W, followed by 3 mg/kg and 200 mg monotherapy dose expansion until disease progression or intolerable toxicity. During combination dose escalation, patients received ascending doses of tifcemalimab (100mg and 200mg) plus toripalimab (240mg). Dose-limiting toxicity (DLT) was evaluated by a safety monitoring committee. Study objectives included safety, pharmacokinetics, and efficacy. Results: By the cutoff date of July 19, 2023, a total of 71 patients were enrolled, including 25 in the monotherapy and 46 in the combination cohorts. The median follow-up time was 57 weeks. The median age was 38 (range 19-70) years with 50 (70%) male patients. The median prior line of therapy was 4 with 54 (76%) progressed upon prior anti-PD-1/L1 therapy. No DLT was observed in either monotherapy or combination dose escalation. Recommended phase 2 dose (RP2D) was determined to be 200 mg tifcemalimab as monotherapy or in combination with toripalimab. Sixty-seven (94%) patients experienced treatment emergent adverse events (TEAEs), 22 (31%) of whom experienced grade 3 or above TEAEs. The most common TEAEs were COVID-19 infection (30%), anemia (30%) and Infusion related reaction (27%). Four treatment-related adverse events led to the discontinuation of the study drug. Among 25 patients receiving monotherapy, 1 PR (follicular lymphoma) and 7 SD were observed with median progression-free survival (PFS) 2.1 months. Among 46 patients receiving combination therapy, 1 CR,16 PR (ORR 37.0%) and 20 SD (DCR 80.4%) were observed and estimated median PFS was 14.7 months. Thirty-four patients with Hodgkin's Lymphoma received RP2D of combination therapy and all of them had received previous chemotherapy and anti-PD-1 or anti-PD-L1 antibody, and 12 PR (ORR 35.3%) and 17 SD (DCR 85.3%) were observed with estimated median progression-free survival was 16.2 months. Conclusions: Tifcemalimab alone or in combination with toripalimab were well tolerated in all doses evaluated. The combination regimen showed favorable safety and durable efficacy in lymphoma patients with heavily pretreatment, providing evidence for future investigation.

Encouraging Efficacy Observed in Bexmab Study: A Phase 1/2 Study to Assess Safety and Efficacy of Bexmarilimab in Combination with Standard of Care in Myeloid Malignancies

Background Clever-1 (common lymphatic endothelial and vascular endothelial receptor-1) constitutes a novel macrophage checkpoint. The receptor contributes to immune tolerance by antigen clearing and T cell inhibition. In multiple models, tumor growth is significantly reduced when Clever-1 function is inhibited. Expression of Clever-1 on bone marrow (BM) cells is a prognostic factor for poor outcome in acute myeloid leukemia (AML) and suppression of Clever-1 signaling inhibits leukemia cell growth. Bexmarilimab (BEX), a humanized IgG4 monoclonal antibody, binds Clever-1 resulting in increased antigen presentation, secretion of proinflammatory cytokines and activation of T cells. Clever-1 is highly expressed on leukemic blasts and monocytes of AML and myelodysplastic syndrome (MDS) patients. Treatment of AML bone marrow cells with BEX alone or in combination with azacitidine/venetoclax results in enhanced antigen presentation capacity and increased activation markers on effector T cells with synergistic effect on cell death. Also, BEX treatment alone lowers blast metabolic fitness via interference with mitochondrial oxidation. The ongoing BEXMAB clinical study investigates safety and efficacy of BEX combined with standard of care (SoC) in patients with myeloid malignancies (NCT05428969). Method This is a Ph1/2 study, investigating BEX combined with azacitidine (doublet) in patients with higher risk MDS frontline or hypomethylating agent (HMA)-failed, and relapsed/refractory (r/r) AML patients. BEX is dosed Q1W in 28-day cycles until disease progression or intolerable toxicity. SoC azacitidine is administered as per label. During Ph1, BEX doses were escalated from 1.0 mg/kg to 6.0 mg/kg (Bayesian optimal interval [BOIN] design). BM was analyzed at the end of Cycle 1 and 3 followed by every three cycles. Ph2 will start with a dose optimization per malignancy followed by a dose expansion for efficacy evaluation (2-Stage design). Results Here we report data from the dose finding Ph1 of the doublet. As of 25 July 2023, 22 patients have been enrolled in the doublet (MDS n=5; MDS HMA failed n=5; r/r AML n=12). Baseline characteristics are shown in Table 1. 8/10 MDS/MDS HMA-failed patients were of high to very high risk based on rIPSS; of the r/r AML 7/12 patients had adverse risk based on ELN 2017. The median number of prior therapies for the MDS HMA-failed patients was 1 (range 1-2). The median number of prior therapies for the r/r AML patients was 2 (range 1-4) with all patients having failed prior HMA-containing therapies and 7/12 having received prior HMA plus venetoclax. The majority of observed adverse events (AE) were Grade 1-2 and no dose limiting toxicities have been reported. As of 25 July 2023, a total of 10 BEX related AEs have been reported (8% of all treatment emergent AEs) with four of these events of ≥ Grade 3, two being immune related (capillary leak syndrome and hemophagocytic lymphohistiocytosis). Sustained target engagement of soluble Clever-1 of up to 75% compared to baseline was seen at all tested dose levels in patient blood. Activity of BEX in patient BM was demonstrated using receptor binding assays with BEX treatment resulting in decreased blast Clever-1 expression at all dose levels of the doublet cohort. Increased immune activation as measured using HLA expression and T/NK cell numbers in patient BM was observed after BEX treatment across indications. Up to 2-3-fold increase of CD8 T and NK cells in the BM of BEX treated patients was observed. Preliminary efficacy shows objective responses in 8/15 evaluable patients across all tested BEX doses. Four were observed in patients with prior HMA-failure and four patients stayed on treatment &amp;gt; 6 months. Clinical activity for frontline MDS was seen as one complete remission (CR), marrow CR (mCR) and hematologic improvement for platelets (HI-P); for MDS with HMA failure as one CR, mCR and partial remission (PR); for r/r AML as two incomplete CRs (CRi). Based on accumulating data, responses are observed between end Cycle 1 and end Cycle 4 for all BEX doses. Conclusion Combining BEX plus azacitidine is well-tolerated and shows efficacy across indications. Additional clinical and pharmacodynamic data of the completed Ph1 of the study will be presented during the meeting. Ph2 of BEX plus azacitidine will open in the 2 nd half of 2023 in HMA-failed r/r AML and/or higher risk MDS patients.

A Phase 1b Study Evaluating the Safety and Efficacy of AK117 (anti-CD47 monoclonal antibody) in Combination with Azacitidine in Patients with Treatment-Naïve Acute Myeloid Leukemia

Background: AK117 is a humanized IgG4 monoclonal antibody that specifically targets CD47, a “don't eat me” signal excessively expressed on tumor cells such as myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML). CD47 blockade effectively stimulates macrophage-mediated phagocytosis of AML cells, and when combined with azacitidine (AZA), it synergistically enhances the activation of “eat me” signals. Here, we report the data from a Phase 1b study of AK117 plus AZA in patients with treatment-naïve AML. Methods: Patients newly diagnosed with AML who were deemed unfit for intensive chemotherapy were included in the study to receive combination therapy with AK117 and AZA. AK117 was administered intravenously (IV) following various dosing regimens (10-20 mg/kg once weekly [QW], or 30-45 mg/kg every 2 weeks [Q2W]), whereas AZA was administered subcutaneously (SC) at the standard dosage (75 mg/m 2, Day 1-7, every 4 weeks [Q4W]). The primary endpoints of the study were safety/tolerability, and composite complete remission (CCR) defined as the combination of complete remission (CR) and complete remission with incomplete hematologic recovery (CRi), based on the 2017 European Leukemia Net (ELN) response criteria. Results: As of June 9, 2023, 40 patients were enrolled (median age: 63 years, 42.5% males, 72.5% with ECOG≥1). Most patients had abnormal hematologic conditions at baseline, including decreased hemoglobin, neutrophil count, and platelet count. Specifically, 80.0% of patients had Grade ≥3 anemia, 62.5% had Grade ≥3 neutrophil count decrease, and 50.0% had Grade ≥3 platelet count decrease. For the recommended phase 2 dose (RP2D) group, treated with a combination of AK117 30 mg/kg Q2W and AZA, 22 patients were enrolled (median age: 63 years, 31.8% males, 72.7% with ECOG≥1). After a median follow-up of 6.7 months (ranging from 0.2-20.7 months), anemia (a primary adverse event associated with CD47 blocking antibodies) occurred in 32.5% (13/40) of the patients. Other commonly observed treatment-emergent adverse events (TEAEs) (≥30%) included decreased white blood cell count (70.0%), decreased lymphocyte count (62.5%), decreased platelet count (55.0%), decreased neutrophil count (52.5%), pyrexia (52.5%), constipation (40.0%), and vomiting (37.5%). The most frequently reported Grade ≥3 TEAEs (≥20%) were decreased white blood cell count (52.5%), decreased platelet count (47.5%), decreased neutrophil count (45.0%), decreased lymphocyte count (25.0%), and anemia (25.0%). One patient (2.5%) discontinued treatment due to TEAE. The efficacy of AK117 was compared at different dosages, and ultimately, 30mg/kg Q2W was chosen as the RP2D. Out of 20 evaluable patients, 11 (55%) achieved a CCR, including 9 (45%) with a CR and 2 (10%) with a CRi. Stable disease (SD) was reported in 35% of the patients. The median time to response (TTR) was 1.31 months, while the median time to CR (TTCR) was 1.84 months. The median duration of response (DoR) and duration of CR (DoCR) were not reached. Conclusions: The combination of AK117 and AZA exhibited a manageable safety profile with a low incidence of anemia, and demonstrated promising efficacy as a first-line treatment in AML patients who were unable to undergo intensive chemotherapy.

Inclacumab Reduce Preexisting Red Blood Cell Adhesion to Activated Endothelial Cells: In-Vitro Assessment of the Microfluidic Platform Endothelium-on-a-Chip

Background: In 2019 FDA approved the use of an antibody anti P-selectin (Crizanlizumab) for the treatment of sickle cell disease (SCD) to reduce the vaso occlusive crisis (VOCs). New anti-adhesive treatments are being developed recently. Global Blood Therapeutics, Inc., acquired by Pfizer Inc. in October 2022, acquired Inclacumab from Roche and started two clinical trials now in phase 3 to evaluate the capacity of this humanized IgG4 monoclonal antibody anti P-selectin to reduce the VOCs in patients with SCD. In our recent work presented at EHA 23 in Frankfurt Germany, we showed that Inclacumab prevents the adhesion of RBCs to chronically and acutely heme activated human umbilical vein endothelial cells (HUVECs) with a statistically significant higher effect in comparison to Crizanlizumab. In this work we used a similar approach to test the capacity of Inclacumab in the reduction of preexisting adhesion events on acutely heme activated HUVECs. Methods:Whole blood EDTA samples from six SCD subjects all with HbSS genotypes were collected at University Hospital Cleveland Medical Center, Cleveland, OH, USA. To standardize the samples, we isolated RBCs by centrifugation and subsequential washes in Phospahte buffer s of the whole blood and resuspended in basal cell culture medium (EBM; Lonza, Morristown, NJ, USA) at a hematocrit of 20% with 10 mM of HEPES. HUVECs (Lonza, Morristown, NJ, USA) were introduced and maintained within the endothelialized microfluidic channels at physiological flow for at least 48-72 hours prior to experiments. We performed an acute short-term activation, where the blood samples were supplemented with 40 µM heme +/- 100 µg/ml injected through the microfluidic channels for 15 minutes, after the adhesion took place we washed the non-adherent cells with Inclacumab and Crizanlizumab and we compared with untreated washing buffer (both compounds were provided by Global Blood Therapeutics, Inc., a wholly owned subsidiary of Pfizer Inc. South San Francisco, CA, USA) A phase-contrast images of the remaining RBCs were acquired with an inverted microscope (DMi8 Leica Microsystems Inc. Deerfield, IL, USA) and quantified based on previous published methods (Figure 1A). Paired t-test was used to calculate statistical significance. Results: Acute short-term heme activation induces high level of RBCs adhesion. Both compounds Inclacumab and Crizanlizumab showed a reduction of the number of adherent RBCs to the activated heme, but only Inclacumab results statistically a significant higher reduction compared to untreated RBCs (Figure 1B). Conclusions: Inclacumab is able not only to prevent the adhesion of RBCs to acutely and chronically activated HUVECs but is able to remove the preexisting adhesion and results in significant higher reduction compared to untreated. RBCs adhesion assay on Endothelium-on-a-chip is a novel and efficient way to study the efficacy of the new antiadhesive drug and could be used to monitor patient response to new therapies in SCD. Figure1 : Effect of Inclacumab vs Crizanlizumab on removal of SCD RBC adhesion to heme activated HUVECs. A) Schematic of adhesion experiment and inverted microscope contrast of phase images 10X of adherent RBCs at acutely heme activated HUVECs. B) Inclacumab has statistically significant effect on remove adherent RBCs to acutely heme activated HUVECs (p=0.009, N=7) For all experiments, the heme concentrations were 40 µM and Inclacumab and Crizanlizumab were 100 µg/ml. Scale bare 20 µm. P-values were based on paired t-test. Error bars represent the standard error of the mean (SEM)

Favezelimab in Combination with Pembrolizumab in Patients with Anti-PD-1-Naive Relapsed or Refractory Classical Hodgkin Lymphoma: Updated Analysis of an Open-Label Phase 1/2 Study

Introduction: Programmed cell death protein 1 (PD-1) inhibitors such as pembrolizumab play an important role in the treatment of patients with relapsed or refractory (R/R) classical Hodgkin lymphoma (cHL), but treatment failure remains a significant challenge. Lymphocyte-activation gene 3 (LAG-3) is an immune checkpoint receptor that downregulates T-cell activity and plays a role in regulating T-cell function. Dual blockade of PD-1 and LAG-3 demonstrated antitumor activity in patients with advanced melanoma in the RELATIVITY-047 trial, which led to FDA approval in this setting. Favezelimab is a humanized IgG4 monoclonal antibody directed against LAG-3 that is being investigated in combination with pembrolizumab in patients with R/R hematologic malignancies in a multicohort phase 1/2 study (NCT03598608). Prior analyses of this study demonstrated that pembrolizumab 200 mg plus favezelimab 800 mg every 3 weeks (Q3W) exhibited sustained antitumor activity and acceptable safety in the cohort of patients with anti-PD-1-naive R/R cHL (cohort 1). We present updated results from this cohort. Methods: A safety lead-in phase to determine the recommended phase 2 dose (RP2D) was followed by a dose-expansion phase. Eligible patients were ≥18 years of age; had R/R cHL after autologous stem cell transplantation (ASCT), were ineligible for ASCT, or did not respond to salvage chemotherapy; had not received prior anti-PD-1 therapy; and had an ECOG performance status of 0 or 1. In the safety lead-in, patients received pembrolizumab 200 mg IV Q3W and favezelimab at a starting dose of 200 mg that was escalated to 800 mg IV Q3W using a modified toxicity probability interval method. In the dose-expansion phase, patients received pembrolizumab 200 mg Q3W plus favezelimab at the established RP2D of 800 mg Q3W for up to 35 cycles (~2 years). CT was performed every 12 weeks and PET at weeks 12 and 24. The primary end point was safety. Objective response rate (ORR) per IWG 2007 criteria by investigator review was a secondary end point. Duration of response (DOR) and progression-free survival (PFS) per IWG 2007 criteria by investigator review and overall survival (OS) were exploratory. Results: Thirty patients with anti-PD-1-naive cHL were enrolled in cohort 1. The median age was 40.5 years (range, 19-82), 17 patients (57%) were male, 16 (53%) had an ECOG performance status of 0, and 24 (80%) had received 3 or fewer prior lines of therapy. At data cutoff (March 2, 2023), 13 patients (43%) had completed 35 cycles of study treatment, 16 (53%) had discontinued treatment (10 [33%] progressive disease, 5 [17%] adverse event [AE], 1 [3%] noncompliance with study drug), and 1 (3%) was ongoing on treatment. The median time from first dose to data cutoff was 31.5 months (range, 24.0-43.2). Treatment-related AEs occurred in 27 patients (90%), of which the most common (≥20%) were hypothyroidism (27%), infusion-related reaction (23%), and fatigue (20%). Grade 3/4 treatment related AEs occurred in 9 patients (30%). Five patients (17%) discontinued treatment because of treatment-related AEs. No deaths due to treatment-related AEs were reported. AEs of clinical interest occurred in 20 patients (67%); 3 patients (10%) had grade 3 events (colitis, pneumonitis, severe skin reaction) and 1 patient (3%) had a grade 4 event (hepatitis). Of 5 patients who received allogeneic stem cell transplantation after discontinuation or completion of study treatment, 1 had a grade 3/4 AE (increased blood bilirubin) that was unrelated to study treatment and resolved. The ORR was 80% (n = 24; 95% CI, 61-92); 10 patients (33%) had a complete response and 14 (47%) had a partial response. Twenty-nine patients (97%) had any reduction in target lesions size from baseline, and 25 (83%) had a reduction of ≥50%. Median DOR was 17.0 months (range, 2.6-30.2), and an estimated 47% of responders remained in response ≥24 months. Median PFS was 19.4 months (95% CI, 9.0-28.5), and the 24-month PFS rate was 46%. Median OS was not reached (NR; 95% CI, NR-NR), and the 24-month OS rate was 93%. Conclusion: With additional follow-up, the combination of favezelimab and pembrolizumab continued to demonstrate sustained antitumor activity and manageable safety in patients with anti-PD-1-naive R/R cHL. Analyses are underway to identify biomarkers predictive of response to the combination of favezelimab and pembrolizumab. Further studies to investigate this combination are warranted.

Fc gamma receptors promote antibody-induced LILRB4 internalization and immune regulation of monocytic AML.

The immune checkpoint leukocyte immunoglobulin-like receptor B4 (LILRB4) is found specifically on the cell surface of acute monocytic leukemia (monocytic AML), an aggressive and common subtype of AML. We have developed a humanized monoclonal IgG1 LILRB4-blocking antibody (h128-3), which improved immune regulation but reduced cell surface expression of LILRB4 in monocytic AML models by 40-60%. Interestingly, most of this effect was neutralized by mutation of the Fc region of the antibody (h128-3/N297A), which prevents interaction with Fc gamma receptors (FcγRs). This suggested that there is FcγR-dependent antigenic modulation underlying h128-3's effects, a mechanism known to alter the function of antibodies targeting B-cell malignancies. We disrupted the Fc-FcγR interaction pharmacologically and with stable CRISPR-Cas9-mediated genetic knockout of FcγRs in monocytic AML cell lines to investigate the role of FcγR-dependent antigenic modulation in the regulation of LILRB4 by h128-3. When FcγRI is inhibited or removed from the surface of monocytic AML cells, h128-3 cannot optimally perform its blocking function, resulting in activation of the LILRB4 inhibitory receptor and leading to a 15-25% decrease in T-cell-mediated cytotoxicity in vitro. In the absence of FcγRI, scaffolding by FcγRIIa allows h128-3 to maintain LILRB4-blocking function. Here we define a FcγR-dependent antigenic modulation mechanism underlying the function of an immunoreceptor blocking antibody for the first time in myeloid malignancy. This research will facilitate the development of safe, precision-targeted antibody therapeutics in myeloid malignancies with greater potency and efficacy.

Preliminary Results of a Phase 1, First-in-Human Study of INA03, an Anti-CD71 Antibody-Drug Conjugate in Patients with Relapsed or Refractory (R/R) Acute Leukemias

Background: Relapsed or refractory (R/R) acute leukemias (AL) represent major therapeutic challenges. Several reports have highlighted the deregulation of iron metabolism in various proliferative tumor models (and notably AL) which includes the over-expression of the transferrin receptor (TfR1/CD71). Our strategy is thus to harness CD71 overexpression to specifically target cytotoxic agents to leukemic cells. INA03 is an antibody drug conjugate (ADC) constituted of a humanized monoclonal IgG 4 against CD71 and MMAE. We herein report the preliminary safety and efficacy data of a phase 1 trial INA03 (NCT03957915) evaluating INA03 in R/R AL. Methods: INA03 is given as 30 minutes IV infusion on days 1 (Loading dose,LD) followed by maintenance injections on D15 for cycle 1 and on D1 and D15 of cycle 2 and beyond. Eligibility criteria are age &amp;gt;18y, ECOG&amp;lt;2, R/R AL after at least one line of treatment with high dose chemotherapy and/or Vidaza and Venetoclax (VEN), LVEF&amp;gt;50%, Creatinine Clearance &amp;gt;30ml/min, normal liver function. The study design is based on a continuous reassessment method and includes 2 parts: a Loading Dose (LD) Titration study (Part 1, completed), followed by a Dose Escalation Part 2. During Part 1, sequential cohorts of 2 pts were included to receive ascending LD of INA03 followed by repeated fixed doses of INA03 to deal with a potential sink effect related to the high expression of CD71 in normal erythroblasts. During Part 2, sequential cohorts of 3 pts received escalating doses of INA03 Q2 weeks in 28-day cycles. The objectives were to establish the maximal tolerated dose (MTD) for subsequent administration and both safety/tolerability and anti-leukemic activity. Results: With a cutoff date of July 05, 2023, 27 patients (pts) across 10 cohorts were included in the study. The median age was 73 (range: 39 - 83), 25 (93%) pts had AML and two (7%) had ALL. Four (14.8%) pts had a prior allogeneic stem cell transplantation and 18 (66.6%) had prior VEN exposure. Pts received escalating doses of INA03 of 0.02 mg/kg to 3 mg/kg. Two patients in the 3 mg/kg loading dose cohort presented a dose limiting toxicity (DLT), one with grade 3 toxic erythema, grade 3 hepatitis and grade 3 mucositis and one with grade 4 colonic perforation. Up to the 2.5 mg/kg dose, no grade 2-4 treatment emerging adverse events (TEAE) were observed among the 19 evaluable pts and only one related grade 1 TEAE (hyperkalemia/phosphatemia) was reported. Transient decrease of reticulocyte count and erythroblasts percentage were observed at 0.5 mg/kg and above. Blasts reductions were seen in 6/20 (30%) evaluable pts at dose &amp;gt; 1 mg/kg including two partial responses according to ELN 2022 classification. MMAE pharmacokinetics (PK) appears dose-proportional with a small accumulation after repeated IV, while INA03 PK exhibits target-mediated drug disposition without accumulation. Conclusions: The preliminary results of this phase 1 study indicate that INA03 is well tolerated for doses up to 2.5 mg/kg. Induction of transient erythroblastopenia indicates effective targeting of CD71 in vivo and early signs of antileukemic efficacy have been observed in patients with refractory AL. Inclusion in the trial are continuing and additional data will be presented.

Phase I/Ib, open-label, multicenter, dose-escalation study of the anti-TGF-β monoclonal antibody, NIS793, in combination with spartalizumab in adult patients with advanced tumors

BackgroundNIS793 is a human IgG2 monoclonal antibody that binds to transforming growth factor beta (TGF-β). This first-in-human study investigated NIS793 plus spartalizumab treatment in patients with advanced solid tumors.MethodsPatients received...

Current and Emerging Therapies for Atopic Dermatitis in the Elderly.

Atopic dermatitis (AD) in the elderly has recently emerged as a distinct subgroup of AD, garnering widespread concern due to its increasing global incidence rate. Epidermal barrier dysfunction, inflammatory response, and chronic pruritus interact with each other, contributing to the pathogenesis andpathophysiology of AD in the elderly. Although fundamental medications are essential for managing AD in the elderly, older adults often struggle with regular usage of moisturizing emollients, topical medications, and avoidance of environmental triggers, leading to recurrent or even exacerbated disease progression. Therefore, a systematic medication approach is necessary to control pruritus and skin lesions. Traditional systemic treatments may not adequately meet the treatment needs of moderate and severe AD in the elderly and may even pose certain safety risks. Biologics and Janus kinase (JAK) inhibitors, exhibiting excellent clinical efficacy, have made significant breakthroughs in AD treatment. Existing evidence suggests that dupilumab, a human monoclonal IgG4 antibody, has been confirmed as an effective and safe first-line systematic treatment for moderate to severe AD in the elderly, with no notable differences between adults and the elderly. However, the limited inclusion of elderly patients in related clinical studies hinders the generalizability of these findings. As older patients face a higher risk of adverse events with JAK inhibitors, JAK inhibitors are recommended when no other suitable treatment options are available. Obtaining population-specific data is crucial for making evidence-based treatment choices when managing AD in older adults with JAK inhibitors.

Sintilimab Injection Combination with Concurrent Chemoradiotherapy (cCRT) in Patients with Localized Esophageal Squamous Cell Carcinoma: A Prospective, Multi-Center, Single-Arm Trial in Progress

Esophageal cancer had accounted for the sixth highest incidence and the fourth highest death rate in China. The predominant histological subtype is esophageal squamous cell carcinoma (ESCC). At initial diagnosis, more than half of patients with ESCC are unfit for surgery. An accepted alternative to surgery is concurrent chemoradiotherapy (cCRT); however, many patients experience local recurrence or distant metastasis after cCRT. Therefore, innovative therapies are needed. Sintilimab is a fully human IgG4 monoclonal antibody, exhibiting the highest affinity for human PD-1 and a lower off-rate, the PD-1 receptor occupancy of sintilimab on circulating T cells is superior. In previous studies, sintilimab, alone and in combination with chemotherapy, was generally well tolerated and had antitumor activity in patients with advanced ESCC. This prospective, single-arm study (NCT04602013) is designed to explore the efficacy of Sintilimab in combination with cCRT. Eligible patients have histologically confirmed localized ESCC for whom cCRT is suitable and surgery is unsuitable/ declined; patients couldn't have received prior chemoradiotherapy. Approximately 53 Chinese patients from 5 centers will be to receive sintilimab (body weight <60kg: 3mg/kg IV Q3W; body weight ≥60kg: 200mg IV Q3W) in combination with cisplatin (25 mg/m2 IV on Days 1-3 of each 3-week cycle) plus paclitaxel for injection (albumin bound) (180 mg/m2). and radiotherapy at a total dose of 60Gy. Duration of treatment will be up to 12 months for sintilimab, including two cycles for concurrent administration of chemotherapy and radiotherapy. Progression-free survival (PFS), assessed by a Blinded Independent Review Committee per RECIST v1.1, is the primary endpoint of the study. Secondary efficacy endpoints include overall response rate, duration of response, and overall survival. Incidence and severity of adverse events (CTCAE V5.0) and patient-reported outcomes of health-related quality of life are additional secondary endpoints. A total of 17 patients have completed sintilimab injection combination with concurrent chemoradiotherapy,17/53 (32%). Objective response rate (ORR) 62.5% and a median progression free survival (mPFS) 17 months. 1-year overall survival (OS) 88.2%. The most common AEs included granulocytopenia (43.7%), thrombo -cytopenia (56.2%), radiation esophagitis (50%), nausea and vomiting (50%), and immune pneumonia (18.7%). Of these AEs greater than grade 3 granulocytopenia (25.0%), thrombocytopenia (35.0%), radiation esophagitis (12.5%), and nausea and vomiting (31.3%), and one patient developed grade 3 immune pneumonia (6.2%), which recovered with treatment. The treatment of sintilimab with CCRT is safe and effective for localized ESCC patients, even with high-dose radiotherapy (60Gy). This study may help to address the unmet need for new therapeutic options for patients with localized ESCC.