Development and Validation of a Specific and Sensitive Anti-Drug Antibody Assay for Abelacimab That Avoids False Positive Results Due to Factor XI Interference

Abelacimab is a fully human IgG1 monoclonal antibody that has dual activity against the inactive zymogen Factor XI (FXI) and the activated Factor XI (FXIa). Clinical trials for this investigational product are ongoing. As part of the initial assessment of abelacimab safety and efficacy, an anti-drug antibody (ADA) assay was validated and implemented in two single ascending dose studies conducted in the United States and Japan in healthy subjects. In those studies, ADA positive results were detected in up to 31.1% of subjects. There was no apparent impact on PK, PD, or development of immunogenicity-adverse events in study subjects who were ADA positive relative to those who were ADA negative in either study. Further, the rates of ADA positive subjects seemed inconsistent with a single administration of a fully human IgG1 monoclonal antibody therapeutic. Given the homodimeric structure of FXI, it appeared that the ADA assay was returning false positive results due to cross-linking through FXI. To address this issue, a novel ADA assay, following the 3-tiered approach of screening, confirmation, and titer determination was developed and validated. The assay was shown to be sensitive, specific, and did not show false positive interference by FXI. Two subsequent clinical trials (ANT-003 A randomized, subject- and investigator-blinded, placebo-controlled study conducted in healthy subjects and in obese, but otherwise healthy, subjects aged 18 to 60 years of age and ANT-004 A randomized, subject- and investigator-blinded, placebo-controlled, multiple ascending dose study in patients with atrial fibrillation (AF) or atrial flutter aged 18 to 85 years old with a CHA 2DS 2-VASc risk score of 0-1 for men and 1-2 for women and in whom the use of an anticoagulant for stroke prevention was not planned for the duration of the trial) showed no treatment-emergent ADA responses from either trial. The screen positive rate from the two studies was approximately 5% with no screen positive samples confirmed as positive indicating that the new assay format successfully addressed the false positive issue, and that the sensitivity was appropriately set to achieve the FDA-recommended 5% false positive rate for ADA assays. Disclosures Cullen: Anthos Therapeutics, Inc: Consultancy. Freedholm: Anthos Therapeutics, Inc: Current Employment, Current holder of stock options in a privately-held company.

TROPION-PanTumor01: Dose analysis of the TROP2-directed antibody-drug conjugate (ADC) datopotamab deruxtecan (Dato-DXd, DS-1062) for the treatment (Tx) of advanced or metastatic non-small cell lung cancer (NSCLC).

9058 Background: Datopotamab deruxtecan (Dato-DXd; DS-1062) is an ADC composed of a humanized anti-TROP2 IgG1 monoclonal antibody conjugated to a topoisomerase I inhibitor via a tetrapeptide-based cleavable linker. Methods: TROPION-PanTumor01 (NCT03401385) is a multicenter dose-escalation/expansion study evaluating Dato-DXd administered Q3W in patients (pts) with advanced NSCLC (since expanded to other tumor types, excluded from this analysis). Efficacy and safety were evaluated in 175 pts for dose analysis. Pharmacometric analyses (population pharmacokinetics [popPK] and exposure-response modeling) were conducted across doses to inform dose selection for further development. Results: At data cutoff (Sept 4, 2020), median follow-up was 7.4 mo (range, 0.10-21.7 mo). Select all-grade TEAEs were 1.5- to 2-fold higher in the 8 mg/kg vs 4 and 6 mg/kg cohorts: vomiting (34% vs 12% and 18%), anemia (28% vs 4% and 16%), diarrhea (20% vs 6% and 11%), and mucositis (29% vs 6% and 13%). Rates of grade ≥3 drug-related TEAEs and serious drug-related TEAEs were ≥2-fold higher with the 8 mg/kg dose (n = 80; 34% and 20%) relative to the 4 mg/kg (n = 50; 10% and 8%) and 6 mg/kg (n = 45; 16% and 9%) doses. Rates of drug-related interstitial lung disease (ILD), as determined by an independent adjudication committee, were higher in the 8 mg/kg cohort (15% vs 2% and 2% in the 4 and 6 mg/kg cohorts); 3 pts in the 8 mg/kg cohort experienced grade 5 ILD. Dose interruptions and reductions due to TEAEs increased with dose (4 mg/kg: 4% and 2%; 6 mg/kg: 20% and 9%; 8 mg/kg: 20% and 31%). More pts in the 8 mg/kg cohort discontinued Tx early due to AEs (15%) compared with those in the 4 mg/kg (4%) and 6 mg/kg (7%) cohorts. ORRs determined by blinded independent central review were similar: 8 mg/kg, 25% (20/80); 6 mg/kg, 21% (8/39); and 4 mg/kg, 23% (9/40). Preliminary median PFS (95% CI) was 5.4 mo (4.1-7.1 mo) in the 8 mg/kg cohort, 8.2 mo (1.5-11.8 mo) in the 6 mg/kg cohort, and 4.3 mo (2.0 mo-NE) in the 4 mg/kg cohort. PFS was limited by early censoring due to immature duration of follow-up, with the majority of pts having ≤3 mo of follow-up in the 4 (66%) and 6 mg/kg (67%) cohorts vs 8 mg/kg (46%) cohort. In pharmacometric analyses, tumor-size change from baseline and probability of complete response/partial response positively correlated with exposure (AUC) of Dato-DXd. Incidences of dose reduction and grade ≥2 stomatitis/mucositis were also positively correlated with exposure; projected probabilities in a virtual population bootstrapped from pts with NSCLC in the popPK data confirmed these trends. Updated results will be presented. Conclusions: A Dato-DXd dose of 6 mg/kg was selected for the randomized, phase 3, TROPION-Lung01 trial (NCT04656652) based on better tolerance and improved efficacy, including a trend toward increased PFS. Clinical trial information: NCT03401385.

Diagnosis and management of X-linked hypophosphatemia in children and adolescent in the Gulf Cooperation Council countries

Introduction X-linked hypophosphatemia (XLH) is a rare inherited cause of hypophosphatemic rickets and osteomalacia. It is caused by mutations in the phosphate-regulating endopeptidase homolog, X-linked (PHEX). This results in increased plasma fibroblast growth factor-23 (FGF23), which leads to loss of renal sodium-phosphate co-transporter expression leading to chronic renal phosphate excretion. It also leads to low serum 1,25-dihydroxyvitamin D (1,25(OH)2D), resulting in impaired intestinal phosphate absorption. Chronic hypophosphatemia in XLH leads to impaired endochondral mineralization of the growth plates of long bones with bony deformities. XLH in children and adolescents also causes impaired growth, myopathy, bone pain, and dental abscesses. XLH is the most frequent inherited cause of phosphopenic rickets/osteomalacia. Hypophosphatemia is also found in calcipenic rickets/osteomalacia as a result of secondary hyperparathyroidism. Thus, chronic hypophosphatemia is a common etiologic factor in all types of rickets. Results There is considerable overlap between symptoms and signs of phosphopenic and calcipenic rickets/osteomalacia. Wrong diagnosis leads to inappropriate treatment of rickets/osteomalacia. Nutritional rickets and osteomalacia are common in the Gulf Cooperation Council countries which include Saudi Arabia, United Arab Emirates, Kuwait, Qatar, Bahrain, and Oman. Due to high levels of consanguinity in the region, genetic causes of phosphopenic and calcipenic rickets/osteomalacia are also common. Conclusion This guideline was developed to provide an approach to the diagnosis of XLH, especially where there is no family history of the disease, and that other related conditions are not mistaken for XLH. We also guide the medical management of XLH with conventional treatment and with burosumab, a recombinant human IgG1 monoclonal antibody to FGF23.

Bamlanivimab does not neutralize two SARS-CoV-2 variants carrying E484K in vitro

The IgG1 monoclonal antibody (mAb) bamlanivimab (LY-CoV555) prevents viral attachment and entry into human cells by blocking attachment to the ACE2 receptor. However, whether bamlanivimab is equally effective against SARS-CoV-2 emerging variants of concern (VOC) is not fully known. Hence, the aim of this study was to determine whether bamlanivimab is equally effective against SARS-CoV-2 emerging VOC. The ability of bamlanivimab to neutralize five SARS-CoV-2 variants including B.1.1.7 (mutations include N501Y and del69/70), B.1.351 (mutations include E484K and N501Y) and P.2 (mutations include E484K in the absence of a N501Y mutation) was analyzed in infectious cell culture using CaCo2 cells. Additionally, we analyzed vaccine-elicited sera after immunization with BNT162b2, and convalescent sera for its ability to neutralize SARS-CoV-2 variants. We found that the variant B.1.1.7, as well as two isolates from early 2020 (FFM1 and FFM7) could be efficiently neutralized by bamlanivimab (titer 1/1280, respectively), however, no neutralization effect could be detected against either B.1.135 or P.2, both harboring the E484K substitution. Vaccine-elicited sera showed slightly decreased neutralizing activity against B1.1.7, B.1.135 and P.2 Our in vitro findings indicate that, in contrast to vaccine-elicited sera, bamlanivimab may not provide efficacy against SARS-CoV-2 variants harboring the E484K substitution. Confirmation of the SARS-CoV-2 variant, including screening for E484K, may be needed before initiating mAb treatment with bamlanivimab to ensure both efficacious and efficient use of the antibody product. Hence, variant-specific mAb agents may be required to treat emerging VOC.

A review of secukinumab in psoriasis treatment

Psoriasis is a systemic immunologic disorder associated with decreased quality of life and numerous co-morbidities, including psoriatic arthritis and cardiovascular disease. Secukinumab, a fully human IgG1 monoclonal antibody, selectively binds IL-17A and is approved by the US FDA and European Medicines Agency for moderate-to-severe plaque psoriasis and psoriatic arthritis. This review examines the efficacy and safety of secukinumab for the treatment of psoriasis using the literature retrieved from the PubMed database. In clinical trials, treatment with secukinumab led to rapid and sustained improvement in Psoriasis Area and Severity Index (PASI) scores, with PASI 90 response rates up to 68.5% at 5 years. Long-term clinical trial and real-world data have established secukinumab as a safe and effective treatment for psoriasis.

Rachitismo ipofosforemico X-linked

X-linked hypophosphatemia (XLH) is an X-linked disorder with dominant penetration, caused by mutations in the PHEX gene, which encodes for an endopeptidase that is predominantly expressed in osteoblasts, osteocytes and odontoblasts. PHEX mutations cause increased production of fibroblast growth factor 23 (FGF23) that in turn leads to hypophosphatemia by causing inhibition of the renal phosphate reabsorption and of the synthesis of active 1,25-dihydroxyvitamin D. In children XLH is characterised by rickets, bone pain, physical dysfunction, impaired growth, disproportionate short stature, lowerlimb deformities, pathological fractures, dental malposition and dental abscesses. Although phenotype may be variable in severity, early diagnosis and treatment are critical to improve outcome. Laboratory tests show hypophosphatemia associated with hyperphosphaturia and elevated alkaline phosphatase, while parathormone and calcium levels are normal. For decades, patients have been treated with conventional therapy, including active vitamin D supplementation and fractionated daily doses of oral phosphate salts. However, these therapies rarely normalise the phenotype. More recently, burosumab, a recombinant human IgG1 monoclonal antibody against FGF-23, has been introduced for the treatment of XLH. In phase 2 trials, burosumab has been shown to improve significantly clinical symptoms, as well as biological and radiological signs of rickets.

Phase I study of SEA-CD40, gemcitabine, nab-paclitaxel, and pembrolizumab in patients with metastatic pancreatic ductal adenocarcinoma (PDAC).

TPS4671 Background: SEA-CD40 is an investigational non-fucosylated, humanized IgG1 monoclonal antibody directed against CD40, a co-stimulatory receptor expressed on antigen-presenting cells (APCs). Activation of CD40 on APCs upregulates cytokine production and co-stimulatory receptors, enhancing tumor antigen presentation to T cells. Preclinical data indicate that treatment of PDAC with chemotherapy in conjunction with a CD40 agonist could enhance antigen presentation and initiate an antitumor immune response (Byrne KT and Vonderheide RH, Cell Rep 2016;15, 2719–32). An ongoing Phase 1 study (SGNS40-001) is evaluating SEA-CD40 as monotherapy and in combination with pembrolizumab in patients with advanced solid or hematologic malignancies. A new cohort is enrolling to evaluate the combination of SEA-CD40, gemcitabine, nab-paclitaxel, and pembrolizumab in PDAC. Methods: The cohort consists of patients with metastatic PDAC who have had no prior therapy for metastatic disease. Patients must be ≥18 years old, with (neo)adjuvant therapy completed >4 months prior to enrollment, ECOG status ≤1, adequate renal, hepatic, and hematologic function, and measurable disease per RECIST v 1.1 criteria. A standard regimen of gemcitabine and nab-paclitaxel on Days 1, 8, and 15 of each 28-day cycle is administered with SEA-CD40 IV on Day 3. Pembrolizumab is administered every 42 days starting on Day 8. The primary objective is antitumor activity; secondary objectives are safety and tolerability and SEA-CD40 and pembrolizumab pharmacokinetics. Efficacy endpoints are confirmed RECIST ORR per investigator (primary), disease control rate (response or stable disease ≥16 weeks), duration of response, PFS, and OS. Disease is assessed every 8 weeks using RECIST and immune-based RECIST (iRECIST). Treatment continues until occurrence of unacceptable toxicity, progressive disease per iRECIST, consent withdrawal, or study closure. Assessment of dose-limiting toxicity will occur initially in groups of 6 patients to identify the recommended phase 2 dose of SEA-CD40 for the cohort. Enrollment to this cohort began in November 2019. Clinical trial information: NCT02376699 .

IBI310 monotherapy or in combination with sintilimab in patients with advanced melanoma: An open-label phase Ia/1b study.

e15111 Background: IBI310 is a humanized IgG1 monoclonal antibody against CTLA-4. The study evaluates the safety and tolerability of IBI310 alone or in combination with sintilimab, a PD-1 inhibitor, in patients (pts) with advanced melanoma. Methods: This phase 1a/1b study contained three parts: Part A, Part B and Part C (NCT03545971). In Part A, pts with advanced melanoma were treated in an accelerated titration design with 0.3 mg/kg IBI310 (Q3W, IV), or a 3+3 escalation design with 1, 2 or 3 mg/kg IBI310 (Q3W, IV), up to 3 cycles. In Part B, pts with advanced melanoma were administrated in a 3+3 escalation design with 1, 2 or 3 mg/kg IBI310 (Q3W, IV) plus sintilimab (200 mg, Q3W, IV) for 4 cycles, followed by sintilimab maintenance therapy (200 mg, Q3W, IV). Part C was dose expansion of the combination therapy. The primary objective was to determine dose-limiting toxicity (DLT) of IBI310 monotherapy and the second was efficacy of the combination therapy. Tumor evaluation was based on RECIST 1.1. Results: As of Nov 12, 2019, 10 pts were enrolled in Part A (median age 55.5), 6 were mucosal melanoma, 3 were acral melanoma and 1 was non-chronic sun damaged (NCSD) melanoma; 17 pts were enrolled in Part B and C (median age 47.0), only 1 (5.9%) was chronic sun damaged (CSD), and 16 (94.1%) were other melanoma types, including 12.5% (2/16) acral, 31.3% (5/16) mucosal and 56.3% (9/16) NCSD melanomas. No DLTs were observed in both Part A and B. In Part A, 9 pts occurred treatment-related adverse events (TRAEs), most commonly pruritus (4 pts), blood thyroid stimulating hormone increased (2 pts), and asthenia (2 pts). No AEs of ≥ grade 3 were reported. Five pts had stable disease (SD). In Part B and C, 13 pts reported TRAEs, only 1 pt occurred grade 3 TRAE (aspartate aminotransferase increased in 3mg dose level), and others reported grade 2, most commonly pruritus (8 pts), rash (7 pts) and alanine aminotransferase increased (6 pts). No AEs leading to death. In evaluable pts in combination with sintilimab, 1 (NCSD melanoma) of 7 pts (3 NCSD, 1 acral, 2 mucosal and 1 CSD melanoma) reached confirmed partial response (PR) in 2 mg group, and 1 (acral melanoma) of 3 pts (1 acral, 1 mucosal and 1 NCSD melanomas) reached confirmed PR in 3 mg group. Five pts had SD. Part C is currently ongoing. Conclusions: IBI310 monotherapy or in combination with sintilimab were well-tolerated without unanticipated AEs in pts with advanced melanoma. The data preliminarily demonstrate an antitumor activity of the combination therapy in previously treated advanced melanoma (acral and NCSD melanomas). Clinical trial information: NCT03545971 .

Formaldehyde Reacts with Amino Acids and Peptides with a Potential Role in Acute Methanol Intoxication

Methanol, an aliphatic alcohol widely used in the industry, causes acute and chronic intoxications associated with severe long-term health damage, including permanent visual impairment, brain damage, mainly necrosis of the basal ganglia and high mortality due to cancer. However, the role of formaldehyde, an intermediate metabolite of methanol oxidation, in methanol toxicity remains unclear. Thus, we studied the reactivity of several amino acids and peptides in the presence of formaldehyde by identifying products by direct infusion electrospray high-resolution mass spectrometry (MS) and matrix-assisted laser desorption-ionization MS. Cysteine, homocysteine and two peptides, CG and CGAG, provided cyclic products with a +12 amu mass shift with respect to the original compounds. The proposed structures of the products were confirmed by high-resolution tandem MS. Moreover, the formation of the products with +12 amu mass shift was also shown for two biologically relevant peptides, fragments of ipilimumab, which is a human IgG1 monoclonal antibody against cytotoxic T-lymphocyte-associated protein 4. Overall, our experimental results indicate that formaldehyde reacts with some amino acids and peptides, yielding covalently modified structures. Such chemical modifications may induce undesirable changes in the properties and function of vital biomolecules (e.g., hormones, enzymes) and consequently pathogenesis.