Human-mouse Chimeric Monoclonal Antibody Research Articles

Epidermal Growth Factor Receptor Targeting in Colorectal Carcinoma: Antibodies and Patient-Derived Organoids as a Smart Model to Study Therapy Resistance.

Colorectal cancer (CRC) is the second leading cause of cancer-related death worldwide. Therefore, the need for new therapeutic strategies is still a challenge. Surgery and chemotherapy represent the first-line interventions; nevertheless, the prognosis for metastatic CRC (mCRC) patients remains unacceptable. An important step towards targeted therapy came from the inhibition of the epidermal growth factor receptor (EGFR) pathway, by the anti-EGFR antibody, Cetuximab, or by specific tyrosine kinase inhibitors (TKI). Cetuximab, a mouse-human chimeric monoclonal antibody (mAb), binds to the extracellular domain of EGFR thus impairing EGFR-mediated signaling and reducing cell proliferation. TKI can affect the EGFR biochemical pathway at different steps along the signaling cascade. Apart from Cetuximab, other anti-EGFR mAbs have been developed, such as Panitumumab. Both antibodies have been approved for the treatment of KRAS-NRAS wild type mCRC, alone or in combination with chemotherapy. These antibodies display strong differences in activating the host immune system against CRC, due to their different immunoglobulin isotypes. Although anti-EGFR antibodies are efficient, drug resistance occurs with high frequency. Resistant tumor cell populations can either already be present before therapy or develop later by biochemical adaptations or new genomic mutations in the EGFR pathway. Numerous efforts have been made to improve the efficacy of the anti-EGFR mAbs or to find new agents that are able to block downstream EGFR signaling cascade molecules. Indeed, we examined the importance of analyzing the anti-EGFR antibody-drug conjugates (ADC) developed to overcome resistance and/or stimulate the tumor host's immunity against CRC growth. Also, patient-derived CRC organoid cultures represent a useful and feasible in vitro model to study tumor behavior and therapy response. Organoids can reflect tumor genetic heterogeneity found in the tissue of origin, representing a unique tool for personalized medicine. Thus, CRC-derived organoid cultures are a smart model for studying the tumor microenvironment and for the preclinical assay of anti-EGFR drugs.

Dosimetry of a Novel 111Indium-Labeled Anti-P-Cadherin Monoclonal Antibody (FF-21101) in Non-Human Primates.

P-cadherin is associated with a wide range of tumor types, making it an attractive therapeutic target. FF-21101 is a human-mouse chimeric monoclonal antibody (mAb) directed against human P-cadherin, which has been radioconjugated with indium-111 (111In) utilizing a DOTA chelator. We investigated the biodistribution of FF-21101(111In) in cynomolgus macaques and extrapolated the results to estimate internal radiation doses of 111In- and yttrium-90 (90Y)-FF-21101 for targeted radioimmunotherapy in humans. Whole-body planar and SPECT imaging were performed at 0, 2, 24, 48, 72, 96, and 120 h post-injection, using a dual-head gamma camera. Volumes of interest of identifiable source organs of radioactivity were defined on aligned reference CT and serial SPECT images. Organs with the highest estimated dose values (mSv/MBq) for FF-21101(111In) were the lungs (0.840), spleen (0.816), liver (0.751), kidneys (0.629), and heart wall (0.451); and for FF-21101(90Y) dose values were: lungs (10.49), spleen (8.21), kidneys (5.92), liver (5.46), and heart wall (2.61). FF-21101(111In) exhibits favorable biodistribution in cynomolgus macaques and estimated human dosimetric characteristics. Data obtained in this study were used to support the filing of an investigational new drug application with the FDA for a Phase I clinical trial.

Characterization of a human-mouse chimeric monoclonal antibody targeting rabies virus glycoprotein.

At present, the horse or human rabies immunoglobulin (RIG) used for postexposure prevention of human rabies (PEP) has high cost and limited availability. It is strongly encouraged to replace RIG with equivalent or more effective and safer products. Mouse and human monoclonal antibodies have been shown to protect rodents from lethal rabies virus (RABV) attacks. In this study, we reported a human-mouse chimeric monoclonal antibody, 12-2A12, which showed a strong neutralization potency and a wide breadth against multiple street viruses of RABV in vitro. The antibody binded the viral glycoprotein (G) with nanomolar affinity. The complex structure of 12-2A12 bound to RABV G revealed that the antibody recognizes an epitope that partially overlaps with the recognition region for the nicotinic acetylcholine receptor (nAChR). The antibody therefore would interfere with the nAChR/G interaction to block the viral receptor binding. In addition, comparison of our complex structure with the G structure in the acidic state reveals a clear steric clash, highlighting that the antibody would further prevent the conformational changes of the viral glycoprotein that are essential for membrane fusion. In light of these functional and structural data, we believe that 12-2A12 might be developed to be included in an antibody cocktail for potential use in human rabies PEP.

Phase 1 trial of HS006, a recombinant human-mouse chimeric anti-CD20 monoclonal antibody to treat CD20 positive B-cell non-Hodgkin's lymphoma in China

Phase 1 trial of HS006, a recombinant human-mouse chimeric anti-CD20 monoclonal antibody to treat CD20 positive B-cell non-Hodgkin's lymphoma in China

Standardization of HIT Diagnostic Assays, with K070, a chimeric human-mouse antibody, mimicking heparin dependent pathogenic antibodies

This study reports the K070 monoclonal antibody, a human-mouse recombinant chimeric monoclonal antibody, IgG1 isotype, targeted to Heparin and PF4 complexes, which mimics Heparin Induced Thrombocytopenia. This antibody has a strong reactivity to Heparin-PF4 complexes, and a much weaker one to PF4 alone. When plasmas spiked with this antibody at concentrations ≥ 0.5 µg/ml are tested at the standard immunoassay dilution, a dose dependent reactivity is obtained. This opens the perspective to use this material to calibrate immunoassays for a quantitative measurement of heparin dependent antibodies, when the disease is suspected. Furthermore, when plasmas are spiked at a higher concentration, from 20 to 200 µg/ml, they test positive in functional assays, like Platelet Aggregation/Activation Tests or Flow Cytometry methods, in presence of a low (0.1-1.0 IU/ml) but not a high (10-100 IU/ml) heparin concentration. In functional assays K070 reactivity level depends on the platelet rich plasmas used. In Platelet Aggregometry Tests some platelet rich plasmas are already positive when tested with plasmas supplemented with 20 µg/ml, whilst others require 100 to 200 µg/ml. At this latter concentration, all tested plasmas generate a strong positive responses with functional assays. K070 is then a useful antibody for calibration of immunoassays and standardization of functional methods used to diagnose Heparin Induced Thrombocytopenia.

CPGJ602 plus mFOLFOX6 as first-line treatment for patients with KRAS/NRAS/BRAF wild-type metastatic colorectal cancer: A randomized phase II study.

3574 Background: CPGJ602 is a recombinant anti-EGFR human-mouse chimeric monoclonal antibody. CPGJ602 plus modified fluorouracil, leucovorin, and oxaliplatin (mFOLFOX6) may have efficacy in KRAS/NRAS/BRAF wild-type metastatic colorectal cancer. Methods: In this open-label, randomized trial, patients who had received no previous treatment were randomly assigned (2:2:1) to receive CPGJ60（325mg/m2, q2w) plus mFOLFOX6 (biweekly group), CPGJ602 (400 mg/m 2 initial dose followed by 250 mg/m2 /week thereafter) plus mFOLFOX6 (weekly group) or cetuximab (400 mg/m2 initial dose followed by 250 mg/m2 /week thereafter) plus mFOLFOX6 (cetuximab group). All subjects received treatment up to 16 weeks. The primary endpoint was the best overall response (BOR) at 16 weeks. The second endpoints were DCR, DOR, PFS, safety. Results: As of Dec 30, 2021, 76 patients were enrolled (30 in biweekly group, 32 in weekly group and 14 in control group). The best overall response achieved at 16 weeks was 76.7% (23/30, 95% CI 60.3% - 92.0%),78.1% (25/32, 95% CI 62.5% - 92.5%) and 78.6% (11/14, 95% CI 49.2% - 95.3%) in the biweekly group, weekly group and cetuximab group, respectively. The confirmed overall response rate at 16 weeks was 60%(18/30), 71.9%(23/32) and 57.1%(8/14) in the biweekly group, weekly group and cetuximab group, respectively. The PFS rates at 16 weeks were 81.5% (95% CI 57.7% -92.6%), 96.8% (95% CI 79.2%-99.5%), 81.3% (95% CI 41.5%- 95.2%) in the biweekly group, weekly group and cetuximab group, respectively. The most common adverse events were a decreased neutrophil count (60%，78.1% and 71.4% in the biweekly group, weekly group and cetuximab group respectively), decreased white-cell count (53.3%, 78.1% and 71.4% respectively), decreased platelet count (40.0%, 40.6% and 42.9% respectively), and elevated serum aspartate aminotransferase (43.3%, 37.5% and 35.7% respectively). Conclusions: CPGJ602 plus mFOLFOX6 could be an option for KRAS/NRAS/BRAF wild-type metastatic colorectal cancer. Clinical trial information: NCT04466254.

Efficacy and Safety of Recombinant Human-Mouse Chimeric Anti-CD20 Monoclonal Antibody (SCT400) Combined with CHOP in Patients with Treatment-Naïve Diffuse Large B-Cell Lymphoma: A Multicenter, Randomized, Single-Blind, Parallel Active-Controlled, Phase III Study

Background:SCT400 is a recombinant, human-mouse chimeric anti-CD20 IgG1 monoclonal antibody and has the same variable regions and antigen-binding site as rituximab. SCT400 has the heavy and κ light chain constant regions of human IgG1 allotype G1m (1,17), which is common in Asians. There is only one amino acid difference between SCT400 and rituximab (V219A in the CH1 domain of the heavy chain). The phase Ⅱ study showed that pharmacokinetics, pharmacodynamics and safety of SCT400 are equivalent to rituximab in patients with CD20-positive non-Hodgkin lymphoma.Objectives:This phase III study aimed to evaluate the safety and efficacy of SCT400 plus cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) compared with rituximab plus CHOP in patients with treatment-naïve diffuse large B-cell lymphoma (DLBCL) (ClinicalTrials.gov, identifier: NCT02772822).Methods:In this multicenter, randomized, single-blind, parallel active-controlled, non-inferiority, phase III study, patients were enrolled from 37 centers in China. Eligible patients were aged 18～75 years with histologically confirmed CD20-positive, treatment-naïve DLBCL; international prognostic index (IPI) 0～2; an Eastern Cooperative Oncology Group (ECOG) performance status (PS) of 0～2. Patients were randomly assigned in a 2:1 ratio to receive either SCT400 plus CHOP (S-CHOP) or rituximab plus CHOP (R-CHOP) every 21 days cycle treatment for six cycles.The primary endpoint was objective response rate (ORR) after six cycles of therapy, assessed by an independent review committee, with a non-inferiority margin of -12%. The secondary endpoints were complete response rate (CRR), progression-free survival (PFS), overall survival (OS), and safety.Results:Between October 19, 2016 and July 13, 2018, 534 patients were screened and 364 eligible patients were randomized to either the S-CHOP group (n=243) or R-CHOP group (n=121). Patient demographics and disease characteristics at baseline were well balanced between the two treatment groups.In the per protocol set (PPS), the best ORRs within six cycles of treatment were 94.5% (95% confidence interval [CI], 90.8% to 97.0%) and 94.1% (95%CI, 88.2% to 97.6%) in the S-CHOP and R-CHOP groups respectively, with an intergroup difference of 0.4% (95%CI, -4.7% to 5.6%, P=0.6569) (Figure 1A). The 95%CI lay on the positive side of the prespecified non-inferiority margin of -12%, meeting the criterion for non-inferiority. The results of using the full analysis set (FAS) were consistent with the primary efficacy analysis in the PPS. No significant differences were observed in the secondary efficacy endpoints, in either the PPS or the FAS (Figure 1B and Figure 2).There were no significant differences were observed in ≥1 adverse event (AE, 97.9% vs. 99.2%), grade≥3 AE (85.2% vs. 86.0%), serious AE (35.4% vs. 38.8%), treatment discontinuation due to AE (7.8% vs.12.4%) between S-CHOP and R-CHOP groups, respectively (Table 1).AEs of special interest occurred in 63.8% of patients in the S-CHOP group and in 59.5% of patients in R-CHOP group, including infection (46.5% vs. 46.3%), infusion-related reaction (20.2% vs. 17.4%), cardiotoxicity (17.7% vs. 11.6%), hepatitis B virus reactivation (1.2% vs. 3.3%), ileus and enterobrosis (1.2% vs. 0.8%), tumor lysis syndrome (0.0% vs. 0.8%) (Table 1).A total of 51 deaths were reported in the S-CHOP group (n=35, 14.4%) and R-CHOP group (n=16, 13.2%), and 10 deaths were due to AE (S-CHOP group: n=7, 2.9%; R-CHOP group: n=3, 2.5%) (Table 1).After treatment, study-drug related anti-drug antibodies (ADAs) were detected in 11(10.9%) patients in S-CHOP group and in 8(16.0%) patients in R-CHOP group (Table 1).Conclusion:SCT400 plus CHOP showed non-inferiority of efficacy to rituximab plus CHOP in patients with treatment-naïve DLBCL. The safety and immunogenicity profiles of SCT400 were comparable with rituximab, with no new treatment-related AE occurred. SCT400 could be a therapeutic option for DLBCL.Funding source:This study was supported by the sponsor, Sinocelltech Ltd., and by grants from the China National Major Project for New Drug Innovation (No. 2018ZX09736002 and No. 2017ZX09304015).Conflicts of interest:Liangzhi Xie is an employee of Sinocelltech Ltd. and has ownership interests in the company. All other authors declare no conflicts of interest. [Display omitted] DisclosuresHu: Astellas Pharma, Inc.: Research Funding. Xie: Sinocelltech Ltd.: Current Employment, Current equity holder in publicly-traded company.

A phase Ib, open-label, dose-escalation trial of the anti-CD37 monoclonal antibody, BI 836826, in combination with gemcitabine and oxaliplatin in patients with relapsed/refractory diffuse large B-cell lymphoma

SummaryBackground BI 836826 is a chimeric mouse–human monoclonal antibody directed against human CD37, a transmembrane protein expressed on mature B lymphocytes. This open-label, phase I dose-escalation trial (NCT02624492) was conducted to determine the maximum tolerated dose (MTD), safety/tolerability, and preliminary efficacy of BI 836826 in combination with gemcitabine and oxaliplatin in patients with relapsed/refractory diffuse large B-cell lymphoma (DLBCL). Methods Eligible patients received intravenous infusions of BI 836826 on day 8 and gemcitabine 1000 mg/m2 plus oxaliplatin 100 mg/m2 on day 1, for up to six 14-day treatment cycles. Dose escalation followed the standard 3 + 3 design. Results Of 21 treated patients, 17 had relapsed/refractory DLBCL and four had follicular lymphoma transformed to DLBCL. BI 836826 dosing started at 25 mg and proceeded through 50 mg and 100 mg. Two dose-limiting toxicities (DLTs) occurred during cycle 1, both grade 4 thrombocytopenia lasting > 7 days, affecting 1/6 evaluable patients (17%) in both the 50 mg and 100 mg cohorts. Due to early termination of the study, the MTD was not determined. The most common adverse events related to BI 836826 treatment were neutropenia (52%), thrombocytopenia (48%), and anemia (48%). Eight patients (38%) experienced BI 836826-related infusion-related reactions (two grade 3). Overall objective response rate was 38%, including two patients (10%) with complete remission and six patients (29%) with partial remission. Conclusions BI 836826 in combination with GemOx was generally well tolerated but did not exceed the MTD at doses up to 100 mg given every 14 days.

Efficacy and safety of different dosages of rituximab for refractory generalized AChR myasthenia gravis: A meta-analysis

BackgroundRituximab (RTX) is a mouse-human chimeric anti-CD20 monoclonal antibody and has been increasingly used for preventing relapses in myasthenia gravis (MG). However, the appropriate dose for maximizing the beneficial effects in refractory MG with acetylcholine receptor (AChR) autoantibody is a long-standing and critical debating question. MethodsWe performed a meta-analysis to evaluate the efficacy and safety of the different doses of RTX in 260 refractory AChR-MG patients. ResultsThe AChR-MG patients were divided into low or routine RTX dose groups. An overall proportion of 77% (p = 0.000) AChR-MG patients demonstrated improved clinical status as indicated by the Myasthenia Gravis Foundation of America post-intervention scale (MGFA-PIS). There were 77.1% patients showed improved clinical status in lower dose of RTX group (p = 0.000) and 76.8% in routine protocol group (p = 0.000). Although we found there was no significant difference in the proportion of AChR-MG patients with improved clinical status or adverse reactions between the two groups, adverse reactions might be lower in the lower dose RTX group. ConclusionMost of refractory MG patients with anti-AChR autoantibody were well responsive and tolerated to RTX treatment. Repeated application of lower dose of RTX was effective and might be more appropriate for refractory AChR-MG patients with potential lower side effects.

Increased rates of cetuximab reactions in tick prevalent regions and a proposed protocol for risk mitigation.

Cetuximab is an anti-epidermal growth factor receptor mouse-human chimeric monoclonal antibody used to treat advanced colorectal cancers. Initial data suggest that severe infusion reactions occurred in 4.5%, many on first exposure. The majority of those with anaphylactic reactions possess predeveloped IgE antibodies to galactose-alpha-1,3-galactose. It is thought that the vector for preexposure to alpha-gal is antigen inoculation via tick bites. This retrospective study reviews the experience of two community cancer centers in high tick exposure areas in Sydney with cetuximab anaphylaxis and proposes a protocol to avoid this. Severe cetuximab infusion reactions occurring in the Northern Cancer Institute Frenchs Forest and St Leonards clinics, Sydney, from May 2014 to February 2019 were recorded. Area of residence was then compared to areas of known high tick prevalence. A total of 87 patients received cetuximab in this period. Six patients (6.9%) experienced at least a grade 3 reaction, three females, age range 41-72 years (median 57.5 years). All were receiving cetuximab for metastatic colorectal cancer and their anaphylaxis occurred with the first infusion in all cases. These cases support the existing theory of increased rates of cetuximab anaphylaxis in areas of high tick prevalence. Given this, we recommend the following protocol for patients being considered for cetuximab therapy: known mammalian meat allergy as an absolute contraindication; all patients receiving cetuximab should have RAST (ImmunoCAP® ) testing for alpha-gal specific-IgE-specific antibodies before first infusion and those who test positive to be considered alternate therapy.

The clinical, laboratory, and radiologic improvement due to siltuximab treatment in idiopathic multicentric Castleman's disease.

Background/AimsIdiopathic multicentric Castleman disease (iMCD) comprises approximately 30% of all cases of Castleman disease. It is characterized by constitutional symptoms, enlarged lymph nodes at multiple anatomical sites, and laboratory test abnormalities, which are primarily related to the overproduction of interleukin 6 (IL-6). Siltuximab is a human-mouse chimeric immunoglobulin G1κ monoclonal antibody against human IL-6. In view of the limited treatment options for iMCD, this study aimed to evaluate the efficacy and safety of siltuximab in the management of this condition.MethodsIn this real-world retrospective study, we administered siltuximab to 15 patients with iMCD who previously received conventional chemotherapy and/or steroid pulse therapy. The median time to a durable symptomatic response was 22 days (range, 17 to 56). The serum hemoglobin and albumin levels and erythrocyte sedimentation rates significantly normalized after the first 3 months of siltuximab treatment. Lymph node involution, assessed using imaging, was relatively gradual, demonstrating a complete or partial response at 6 months.ResultsOn an average, the improvements in clinical, laboratory, and radiologic parameters of iMCD in responders were observed after one, three, and eight cycles of siltuximab treatment, respectively. Siltuximab demonstrated a favorable safety profile, and prolonged treatment was well-tolerated.ConclusionsDespite the small sample size of the present study, the results are encouraging and demonstrate the potential of siltuximab as the first-line treatment of iMCD. Further large multicenter studies are needed to evaluate the clinical outcomes and adverse events associated with siltuximab.

Advances in antibody therapy for B cell lymphoma

Almost 20 years have passed after rituximab, an anti-CD20 mouse-human chimeric monoclonal antibody therapeutic, was introduced in the clinical setting for the treatment of CD20-positive B cell malignancies. Although the prognosis has significantly improved in most B cell malignancies, resistance to rituximab with/without chemotherapies is also widely recognized. With this background, newer generation antibody therapeutics and other molecular targeting drugs that show more effectiveness especially to refractory patients are critically required. In this review, molecular mechanisms of the second/third generation anti-CD20 antibodies (ofatumumab and obinutuzumab), anti-CD19 chimeric antigen-receptor T-cells (CAR-T-CD19; tisagenlecleucel, axicabtagene ciloleucel), and the anti-PD-1 antibodies (nivolumab and pembrolizumab) are presented. The therapeutic effectiveness of those drugs as monotherapy and/or combined therapy with conventional chemotherapy (immunochemotherapy) and another molecular targeting therapeutics (so-called "chemo-free" regimens) are also reviewed.

Plasma infliximab monitoring contributes to optimize Takayasu arteritis treatment: a case report

BackgroundInfliximab (IFX), a mouse-human chimeric monoclonal antibody against human tumor necrosis factor alpha, is used in refractory cases of Takayasu arteritis. Several factors influence the pharmacokinetics of therapeutic antibodies including IFX. Monitoring plasma levels of IFX could be a useful approach in optimizing treatment via individual dose adjustment.Case presentationHere, we report the case of a 4-year-old Takayasu arteritis girl who was resistant to standard therapy. IFX was started at 5 mg/kg (day 0). C-reactive protein (CRP) levels decreased from 8.7 (day 0) to 1.6 mg/dL (day 10). CRP levels were thereafter elevated again on day 23 (9.0 mg/dL), and body fluid leakage at the inflammation site in the legs was observed. Trough IFX levels decreased from 23.6 (day 10) to 2.5 μg/mL (day 23). Based on the trough levels, IFX was given biweekly at 8 mg/kg. Plasma IFX levels gradually increased, and CRP levels decreased to around 2 mg/dL. A similar pattern -initial decreases followed by increases- was observed between clinical course of IFX and IgG levels. It was speculated that IgG and IFX losses were due to fluid leakage from the patient’s necrotizing legs.ConclusionsMonitoring of plasma IFX levels can be a potential tool to optimize the treatment in Takayasu arteritis patients.

Abstract CT128: Phase 1 study of FF-21101(90Y), a radioimmunotherapeutic (RIT) targeting P-cadherin, in advanced solid tumors

Abstract Background: Overexpression of P-cadherin, a calcium-dependent cell-to-cell adhesion glycoprotein, correlates with increased tumor cell invasiveness in breast, colon, lung and pancreatic tumors. FF-21101 is a human-mouse chimeric monoclonal antibody directed against P-cadherin, conjugated with 111In for dosimetry and biodistribution and 90Y for therapy. We report the biodistribution and preliminary anti-cancer activity of FF-21101(90Y) in a first-in-human study. Methods: Patients (pts) received 5 mCi/5mg FF-21101(111In) 1 week before the FF-21101(90Y) therapeutic dose to assess biodistribution and ensure 90Y radiation dose estimates did not exceed the maximum tolerated dose (MTD) for each organ. Single therapeutic dose cohorts were planned for FF-21101(90Y) (8 mCi/mg) at 5, 10, 15, 20 or 25 mCi/m2 (3+3 dose escalation schema), with repeat doses allowed every 4 months in pts demonstrating clinical benefit. Disease assessments were based on RECIST V1.1. Pre-treatment tumor samples were assessed for P-cadherin expression by immunohistochemistry (IHC). Pharmacokinetics (PK) of FF-21101 were also assessed. Results: Fourteen pts (6M, 8F) with advanced primary solid tumors and loco-regional metastases were treated in the 5 dose cohorts. Median (range) values: age 58 years (31 – 69), number of prior systemic treatments 3 (0 – 9), tumor types: soft-tissue sarcoma (3), ovarian carcinoma (CA) (2), and vaginal CA, pancreatic neuroendocrine tumor (PNET), desmoplastic small round cell tumor, colorectal CA, appendiceal CA, cholangiocarcinoma, squamous cell CA (SCC) of the anus, papillary thyroid CA and carcinoid (1 each). Primary and/or metastatic tumors from 12 of 14 pts (85.7%) demonstrated uptake of FF-21101(111In) with highest uptake seen in epithelial tumors, consistent with P-cadherin targeting. Median (range) time on study following the therapeutic dose was 21 (2 - 62) weeks, with 3 pts on study > 1 year (2 ovarian CA, 1 carcinoid). Four pts have received multiple treatments. One ovarian CA pt achieved a partial response (65% reduction); this pt also had the highest H score by IHC staining. High H scores (≥ 100) were demonstrated in 5 of 13 pts: 2 ovarian, 1 PNET, 1 SCC of the anus, 1 cholangiocarcinoma; 4 remained on study for 49 - 62 weeks, thus demonstrating the potential predictive utility of pre-treatment tumor P-cadherin expression. FF-21101(90Y) has been well-tolerated; the MTD has not been reached. The most frequently reported drug-related AEs include lymphopenia (n = 8), thrombocytopenia (n = 4) and leukopenia (n = 3); Gr 3 lymphopenia was observed in 3 pts, all reversible. There have been no drug-related serious AEs. Mean FF-21101 Cmax and AUC0-t increased with dose, suggesting linear PK. Conclusions: Tumor P-cadherin overexpression provides an attractive target for RIT. Radiolabeled FF-21101 exhibits favorable dosimetry and biodistribution, good tolerability and preliminary evidence of anti-cancer activity. Pre-treatment tumor P-cadherin expression may be an important biomarker for patient selection. Citation Format: Vivek Subbiah, William Erwin, Osama Mawlawi, Carlos Gonzalez-Lepera, Masahiko Tokura, Michael Kurman, Holly Liu, David S. Hong, Funda Meric-Bernstam, Shubham Pant, Mary Johansen, Timothy Madden, Elmer Santos, Gregory Ravizzini. Phase 1 study of FF-21101(90Y), a radioimmunotherapeutic (RIT) targeting P-cadherin, in advanced solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr CT128.

The Effect of and Mechanism Underlying Autophagy in Hepatocellular Carcinoma Induced by CH12, a Monoclonal Antibody Directed Against Epidermal Growth Factor Receptor Variant III

Background/Aims: Epidermal growth factor receptor variant III (EGFRvIII), the most frequent EGFR variant, is constitutively activated without binding to EGF and is correlated with a poor prognosis. CH12, a human-mouse chimeric monoclonal antibody, has been developed in our laboratory and selectively binds to overexpressed EGFR and EGFRvIII. A previous study had reported that EGFR could influence autophagic activity, and autophagy is closely related to tumor development and the response to drug therapy. In this study, we aimed to elucidate the effect of CH12 on autophagy and efficacy of combining CH12 with an autophagy inhibitor against EGFRvIII-positive tumors. Methods: EGFRvIII was overexpressed in liver cancer, glioblastoma and breast cancer, and the change in the autophagy-relevant protein levels was analyzed by western blot assays, LC3 punctate aggregation was analyzed by immunofluorescence. The interaction of Beclin-1 and Rubicon was assessed by co-immunoprecipitation (Co-IP) after CH12 treatment. The efficacy of ATG7 or Beclin-1 siRNA in combination with CH12 in Huh-7-EGFRvIII cells was assessed by CCK-8 assays. The autophagy and apoptosis signaling events in Huh-7-EGFRvIII cells upon treatment with control, CH12, siRNA or combination for 48 h were assessed by western blot assays. Results: Our results showed that, in cancer cell lines overexpressing EGFRvIII, only the liver cancer cell lines Huh-7 and PLC/PRF/5 suggested autophagy activation. We then investigated the mechanism of autophagy activation after EGFRvIII overexpression. The results showed that EGFRvIII interacted with Rubicon, an autophagy inhibition protein, and released Beclin-1 to form the inducer complex, thus contributing to autophagy. In addition, CH12, via inhibiting the phosphorylation of EGFRvIII, promoted the interaction of EGFRvIII with Rubicon, further inducing autophagy. In vitro assays suggested that knocking down the expression of the key proteins ATG7 or Beclin-1 in the autophagy pathway with siRNA inhibits tumor cell proliferation. Combining autophagy-related proteins 7 (ATG7) or Beclin-1 siRNA with CH12 in Huh-7-EGFRvIII cells showed better inhibition of cell proliferation. Conclusion: EGFRvIII could induce autophagy, and CH12 treatment could improve autophagy activity in EGFRvIII-positive liver cancer cells. The combination of CH12 with an autophagy inhibitor or siRNA against key proteins in the autophagy pathway displayed more significant efficacy on EGFRvIII-positive tumor cells than monotherapy, and induced cell apoptosis.

Anti-Rituximab antibody in patients with NMOSDs treated with low dose Rituximab

BackgroundRituximab is a mouse-human chimeric anti-CD20 monoclonal antibody and has been increasingly used for preventing relapses in NMOSDs. The clinical relevance of Anti-Rituximab antibodies (ARA) against Rituximab in NMOSDs is unknown. MethodsNineteen NMOSDs patients receiving repeated 100mg Rituximab treatment were recruited. The ARA was quantitatively analyzed by enzyme linked immunoassay. Annualized relapse rate (ARR) and Expanded Disability Status Scale (EDSS) were analyzed concurrently. ResultsARR was reduced markedly since starting Rituximab therapy in the majority (78.9%) of NMOSDs patients. 36.9% (7/19) patients were ARA positive. There was no significant difference in the improvement of ARR and EDSS after treatment with Rituximab in either ARA positive or negative groups. The frequency of Rituximab reinfusion was higher in patients with ARA, suggesting that the presence of ARA led to an increased frequency of Rituximab reinfusion to maintain B cell depletion. ConclusionThe majority of (78.9%) patients with NMOSDs were responsive to low dose Rituximab. The presence of ARA is associated with the requirement for increased frequency of Rituximab reinfusion to maintain treatment response in NMOSDs. In patients with ARA it might be necessary to detect ARA levels and monitor B cell depletion closely, or even attempt other treatments.

Amatuximab and novel agents targeting mesothelin for solid tumors.

Mesothelin (MSLN) is considered a promising target for cancer therapy. Originally extracted in 1992 after the immunization of mice with a human ovarian cancer (OC) cell line and cloned in 1996, MSLN seems to be involved in cell adhesion and metastasis. MSLN is prevalent in mesothelia tissues but is expressed in several human cancers, such as OC, pancreatic cancer, mesothelioma, and lung cancer. Amatuximab (MORAb-009) is a mouse-human chimeric monoclonal antibody with a selective affinity for MSLN. The principal mechanism of action comprises inhibition of binding of MSLN with the antigen CA125/MUC16. The highest phase of development is actually a Phase II trial (MORAb-009-201, Europe). In this review, we describe the mechanism of action of amatuximab and other MSLN-targeting novel drugs, along with a discussion about the expected efficacy, safety, and toxicity of this promising group of agents and implications for future research and clinical practice.

Abstract CT097: Phase 1 study of FF-21101(90Y), a radioimmunotherapeutic targeting P-cadherin, in advanced solid tumors

Abstract Background: CDH3 gene overexpression of P-cadherin correlates with increased tumor cell invasiveness and is observed in breast, colon, lung, and pancreatic tumors. FF-21101 is a human-mouse chimeric monoclonal antibody directed against P-cadherin, conjugated with 111In for dosimetry and 90Y for therapy. This first-in-human study assesses dosimetry (biodistribution) and therapeutic outcome of FF-21101(90Y). Methods: For dosimetry, patients (pts) received 5 mCi/5mg FF-21101(111In) 1 week before the FF-21101(90Y) therapeutic dose to assess biodistribution and ensure 90Y radiation dose estimates did not exceed the recommended allowable limit for each organ. Single therapeutic dose cohorts were planned for FF-21101(90Y) (8 mCi/mg) at 5, 10, 15, 20 or 25 mCi/m2 (3+3 dose escalation schema), with repeat doses allowed every 4 cycles. Disease assessments were based on RECIST V1.1. Pre-treatment tumor samples were assessed for P-cadherin expression by immunohistochemistry (IHC). Pharmacokinetics (PK) of FF-21101 also were assessed. Results: Seven pts (3M, 4F) with advanced primary solid tumors and loco-regional metastases were treated with FF-21101(90Y) in the first 3 dose cohorts. Median (range) values: age 55 years (31 – 69), number of prior treatments, including surgery, radiation and/or chemotherapy 5 (2 – 8); tumor types: ovarian carcinoma (CA) (2 pts), vaginal CA, pancreatic neuroendocrine tumor (PNET), desmoplastic small round cell (DSRC) tumor, colorectal CA (CRC), recurrent liposarcoma (1 pt each). Primary and/or metastatic tumors from 4 of 7 pts (57.1%) demonstrated positive uptake of FF-21101(111In). Highest uptake was seen in epithelial tumors, consistent with P-cadherin targeting. Median (range) time on study following the FF-21101(90Y) dose was 8 (4 – 40) weeks. The vaginal CA pt demonstrated an 18.5% decrease as best response through 16 weeks following a single therapeutic dose. A viable pre-study tumor sample was not available for IHC staining. Pre-treatment tumor samples available from 6 of 7 patients demonstrated high H scores (≥ 100) in 3 pts (50%); 2 ovarian and 1 PNET; all remain on study through 4, 12 and 40 weeks, respectively, thus demonstrating the potential predictive utility of pre-treatment tumor P-cadherin expression. FF-21101(90Y) has been well-tolerated. Drug-related adverse events (AEs) include Gr 1 rash (1 pt) and increased AST (Gr 1/2, 2 pts) at 5 mCi/m2, and lymphopenia (1 Gr 3 in 3 pts at 10 mCi/m2), all reversible. There have been no drug-related serious AEs. Mean FF-21101 Cmax and AUC0-t increased with dose, suggesting linear PK. Conclusions: Tumor P-cadherin overexpression provides an attractive target for radioimmunotherapy. FF-21101(111In/90Y) exhibits favorable dosimetry, good tolerability and preliminary evidence of reduction in tumor burden. Pre-treatment tumor P-cadherin expression may be an important biomarker for patient selection. Citation Format: Vivek Subbiah, William Erwin, Osama Mawlawi, Carlos Gonzalez Lepera, Masahiko Tokura, Masayuki Kawakami, Holly Liu, Shubham Pant, Michele Rosner, Mary Johansen, Louis De Palatis, Thomas Myers, Linda Paradiso, Elmer Santos, Gregory Ravizzini. Phase 1 study of FF-21101(90Y), a radioimmunotherapeutic targeting P-cadherin, in advanced solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr CT097. doi:10.1158/1538-7445.AM2017-CT097

Dinutuximab in the Treatment of High-Risk Neuroblastoma in Children

Neuroblastoma is the most common extracranial tumor derived from neural crest cells in childhood, and treatment of high-risk neuroblastoma is a difficulty in oncology field. The discovery of new treatment strategies to treat pediatric patients with high-risk neuroblastoma is important. Dinutuximab (ch14.18; Unituxin), a chimeric human-mouse monoclonal antibody, is approved by Food and Drug Administration in 2015 to be used specifically in the treatment of high-risk neuroblastoma. It binds the disialoganglioside (GD2) antigen on the surface of neuroblastoma cells and induces lysis of GD2-expressed neuroblastoma cells via antibody-dependent cell-mediated cytotoxicity and complement-dependent cytotoxicity. To enhance its activity, it is used with a combination of granulocyte-macrophage colony-stimulating factor, interleukin 2, and 13-cis-retinoic acid. In this review, we discuss the use of dinutuximab in the treatment of high-risk neuroblastoma.

A Blood Dendritic Cell Vaccine for Acute Myeloid Leukemia

Many acute myeloid leukemia (AML) patients achieve a complete remission (CR) with chemotherapy but relapse is common. Removal of residual disease remains the greatest challenge. Allogeneic transplantation (alloHCT) addresses this through an immune-mediated graft versus leukemia effect (GVL), but has high morbidity and mortality. Therapeutic dendritic cell (DC) vaccination has the potential to provide immune control with limited toxicity. Previous trials using monocyte-derived DC (Mo-DC) have demonstrated modest clinical effects. This is understandable as Mo-DC have demonstrably poor migration in vivo and relatively inferior antigen processing and presentation compared to blood dendritic cells (BDC). We have developed a more practical, functionally superior vaccine composed of natural blood DC (BDC). This is achieved using the human-mouse chimeric monoclonal antibody CMRF-56 to enrich BDC from patient peripheral blood after a short incubation.We assessed the potential for preparing a CMRF-56+ BDC vaccine from AML patients in CR.We developed an extended flow cytometry panel to distinguish different BDC subsets from blasts in AML, sorted them to confirm morphology, then used TruCount methodology to enumerate them at diagnosis, post-chemotherapy (5-28 weeks) and post alloHCT. We correct previous reports that suggested BDC numbers are normal at AML diagnosis by demonstrating that the Lineage- HLA-DR+ CD11c+ cells commonly classified as myeloid DC contain myeloblasts. Exclusion of myeloblasts, revealed that CD1c and CD141 BDC are grossly depleted at AML diagnosis to 567/mL and 24/mL, 4% and 3% respectively of the the levels of healthy aged-matched controls (HC) (n=9; n=13), but recovered to 7323/mL and 294/mL, representing 57% and 39% HC levels (n=12) during CR1, and to 10282/mL and 299/mL, representing 80% and 40% of HC after alloHCT (n=6). In contrast, plasmacytoid dendritic cells (pDC) levels were 2229/mL and 27% of HC at diagnosis, but failed to recover further remaining at 1453/mL or 18% of HC at CR1 and at 1986/mL and 24% of HC post alloHCT. CD1c BDC from AML patients in CR upregulated the CMRF-56 antigen,. similarly to HC (n=5, p=0.4) but primary AML blasts did not, enabling myeloblast free, CMRF-56+ BDC purifications. CMRF-56+ BDC isolated from AML patients in CR expanded anti-viral and Wilms' Tumour 1-specific autologous CD8+ T cells in vitro. However, patients who failed standard induction chemotherapy and required fludarabine-containing salvage regimens produced good CMRF-56+ BDC preparations but did not expand functional T cells.These data support the feasabillity of preparing a functional BDC vaccine from AML patients in CR using CMRF-56 immune selection and highlight the potential detrimental effects of specific chemotherapeutics on cellular therapy. BDC vaccination may consolidate chemotherapy induced CR in AML, or enhance GVL post alloHCT, by stimulating specific immune responses to control residual disease. DisclosuresHsu:DendroCyte BioTech Ltd: Other: Laboratory IP contracted via ANZAC Research Institute to DendroCyte BioTech Ltd. Bryant:DendroCyte BioTech Ltd: Other: Laboratory IP contracted via ANZAC Research Institute to DendroCyte BioTech Ltd. Fromm:DendroCyte BioTech Ltd: Other: Laboratory IP contracted via ANZAC Research Institute to DendroCyte BioTech Ltd. Papadimitrious:DendroCyte BioTech Ltd: Other: Laboratory IP contracted via ANZAC Research Institute to DendroCyte BioTech Ltd. Orellana:DendroCyte BioTech Ltd: Other: Laboratory IP contracted via ANZAC Research Institute to DendroCyte BioTech Ltd. Suen:DendroCyte BioTech Ltd: Other: Laboratory IP contracted via ANZAC Research Institute to DendroCyte BioTech Ltd. Yang:DendroCyte BioTech Ltd: Other: Laboratory IP contracted via ANZAC Research Institute to DendroCyte BioTech Ltd. Weatherburn:DendroCyte BioTech Ltd: Other: Laboratory IP contracted via ANZAC Research Institute to DendroCyte BioTech Ltd. Gasiorowski:DendroCyte BioTech Ltd: Other: Laboratory IP contracted via ANZAC Research Institute to DendroCyte BioTech Ltd. Iland:DendroCyte BioTech Ltd: Other: Laboratory IP contracted via ANZAC Research Institute to DendroCyte BioTech Ltd. Brown:DendroCyte BioTech Ltd: Other: Laboratory IP contracted via ANZAC Research Institute to DendroCyte BioTech Ltd. Joshua:DendroCyte BioTech Ltd: Other: Laboratory IP contracted via ANZAC Research Institute to DendroCyte BioTech Ltd. Ho:DendroCyte BioTech Ltd: Other: Laboratory IP contracted via ANZAC Research Institute to DendroCyte BioTech Ltd. Gibson:DendroCyte BioTech Ltd: Other: Laboratory IP contracted via ANZAC Research Institute to DendroCyte BioTech Ltd. Clark:DendroCyte BioTech Ltd: Equity Ownership, Other: Laboratory IP contracted via ANZAC Research Institute to DendroCyte BioTech Ltd. Hart:DendroCyte BioTech Ltd: Equity Ownership, Other: Laboratory IP contracted via ANZAC Research Institute to DendroCyte BioTech Ltd.