Modelled impact of virtual fractional flow reserve in patients undergoing coronary angiography (VIRTU-4).

BACKGROUND: The practical application of 'virtual' (computed) fractional flow reserve (vFFR) based on invasive coronary angiogram (ICA) images is unknown. The objective of this cohort study was to investigate the potential of vFFR to guide the management of unselected patients undergoing ICA. The hypothesis was that it changes management in >10% of cases. METHODS: vFFR was computed using the Sheffield VIRTUheart system, at five hospitals in the North of England, on 'all-comers' undergoing ICA for non-ST-elevation myocardial infarction acute coronary syndrome (ACS) and chronic coronary syndrome (CCS). The cardiologists' management plan (optimal medical therapy, percutaneous coronary intervention (PCI), coronary artery bypass surgery or 'more information required') and confidence level were recorded after ICA, and again after vFFR disclosure. RESULTS: 517 patients were screened; 320 were recruited: 208 with ACS and 112 with CCS. The median vFFR was 0.82 (0.70-0.91). vFFR disclosure did not change the mean number of significantly stenosed vessels per patient (1.16 (±0.96) visually and 1.18 (±0.92) with vFFR (p=0.79)). A change in intended management following vFFR disclosure occurred in 22% of all patients; in the ACS cohort, there was a 62% increase in the number planned for medical management, and in the CCS cohort, there was a 31% increase in the number planned for PCI. In all patients, vFFR disclosure increased physician confidence from 8 of 10 (7.33-9) to 9 of 10 (8-10) (p<0.001). CONCLUSION: The addition of vFFR to ICA changed intended management strategy in 22% of patients, provided a detailed and specific 'all-in-one' anatomical and physiological assessment of coronary artery disease, and was accompanied by augmentation of the operator's confidence in the treatment strategy.

Drive-by collection and self-fitting of ambulatory electrocardiogram monitoring.

Ambulatory electrocardiogram (AECG) monitoring is a common cardiovascular investigation. Traditionally, this requires a face-to-face appointment. In order to reduce contact during the COVID-19 pandemic, we investigated whether drive-by collection and self-fitting of the device by the patient represents an acceptable alternative. A prospective, observational study of consecutive patients requiring AECG monitoring over a period of one month at three hospitals was performed. Half underwent standard (face-to-face) fitting, and half attended a drive-by service to collect their monitor, fitting their device at home. Outcome measures were quality of the recordings (determined as good, acceptable or poor), and patient satisfaction. A total of 375 patients were included (192 face-to-face, 183 drive-by). Mean patient age was similar between the two groups. The quality of the AECG recordings was similar in both groups (52.6% good in face-to-face vs. 53.0% in drive-by; 34.9% acceptable in face-to-face vs. 32.2% in drive-by; 12.5% poor in face-to-face vs. 14.8% in drive-by; Chi-square statistic 0.55, p=0.76). Patient satisfaction rates were high, with all patients in both groups satisfied with the care they received. In conclusion, drive-by collection and self-fitting of AECG monitoring yields similar AECG quality to conventional face-to-face fitting, with high levels of patient satisfaction.

An Antibody-Drug Conjugate Targeting MUC1-Associated Carbohydrate CA6 Shows Promising Antitumor Activities.

Glycosylation is a complex multienzyme-related process that is frequently deregulated in cancer. Aberrant glycosylation can lead to the generation of novel tumor surface-specific glycotopes that can be targeted by antibodies. Murine DS6 mAb (muDS6) was generated from serous ovary adenocarcinoma immunization. It recognizes CA6, a Mucin-1 (MUC1)-associated sialoglycotope that is highly detected in breast, ovarian, lung, and bladder carcinomas. SAR566658 antibody-drug conjugate (ADC) is a humanized DS6 (huDS6) antibody conjugated through a cleavable linker to the cytotoxic maytansinoid derivative drug, DM4. SAR566658 binds to tumor cells with subnanomolar affinity, allowing good ADC internalization and intracellular delivery of DM4, resulting in tumor cell death (IC50 from 1 to 7.3 nmol/L). SAR566658 showed in vivo antitumor efficacy against CA6-positive human pancreas, cervix, bladder, and ovary tumor xenografts and against three breast patient-derived xenografts. Tumor regression was observed in all tumor models with minimal effective dose correlating with CA6 expression. SAR566658 displayed better efficacy than standard-of-care nontargeted tubulin binders. These data support the development of SAR566658 in patients with CA6-expressing tumors.

Identification and characterization of co-purifying CHO host cell proteins in monoclonal antibody purification process.

Host cell proteins (HCPs) are process-related impurities derived from the host organism such as Chinese hamster ovary (CHO) cells used for the production of therapeutic mAbs in biopharmaceuticals and potentially pose a risk to patient safety and product efficacy. A number of HCPs have been reported as exceptionally difficult to remove and persist across downstream purification operations into final drug product because they exhibit association with mAbs. Therefore, understanding of HCP impurities and the mAb itself will provide insights into the rational design of efficient downstream process. The aim of this work is to understand mAb interaction with HCPs and identify co-purified HCP subpopulations using two different approaches: (1) Incubation of purified mAb with harvest cell culture fluid (HCCF) from mock-transfected CHO cells (null HCCF) or (2) Immobilization of mAb onto chromatography media followed by incubation with null HCCF. CHO HCP ELISA was used to semi-quantitatively measure the levels of total HCPs. Orthogonal techniques including 2-DE and LC-MS/MS were applied to detect variations in CHO HCP profiles and species. The HCP contents in protein A product pools were significantly higher compared to that in control sample without mAb spiked in and variable HCP levels shown in three different protein A product pools. The majority of HCPs identified by LC-MS/MS in the three protein A product pool showed overlap with the HCP identified in eluate pools from the column immobilized with three different mAbs. The interacting HCPs associated with mAbs were largely involved in catalytic activity. Both approaches demonstrated mAbs bind a common set of HCPs as well as HCPs unique to the mAb.

Development and Characterization of a Neutralizing Anti-idiotype Antibody Against Mirvetuximab for Analysis of Clinical Samples.

Antibody-drug-conjugates (ADCs) are an emerging class of biological therapeutics. Mirvetuximab soravtansine is a novel folate receptor alpha (FRα)-targeting ADC which represents a potential new treatment for patients with ovarian and other FRα-positive cancers. Since patient immune responses to biological therapeutics may negatively affect drug efficacy and patient safety, regulatory authorities require rigorous monitoring of patient samples. Taking advantage of the immune system's ability to generate highly specific antibodies, the field has turned to anti-idiotype antibodies as powerful tools for the development of sensitive and specific bioassays. Here, we report the generation and characterization of a highly specific neutralizing anti-idiotype antibody directed against M9346A, the antibody moiety of mirvetuximab soravtansine. The anti-idiotype antibody recognizes M9346A with double-digit picomolar affinity, competes with folate receptor antigen for binding to M9346A, and can be used to develop both anti-drug-antibody and neutralizing antibody assays.

Assessment of an incidental finding of left bundle-branch block.

Incidental left bundle-branch block occurs in up to 1.5% of healthy adults without symptoms or signs of cardiovascular disease. It may be found during investigation for non-cardiac disease, during preoperative assessment, private health screening or inpatient monitoring. This article outlines how to assess these patients.

IMGN853, a Folate Receptor-α (FRα)-Targeting Antibody-Drug Conjugate, Exhibits Potent Targeted Antitumor Activity against FRα-Expressing Tumors.

A majority of ovarian and non-small cell lung adenocarcinoma cancers overexpress folate receptor α (FRα). Here, we report the development of an anti-FRα antibody-drug conjugate (ADC), consisting of a FRα-binding antibody attached to a highly potent maytansinoid that induces cell-cycle arrest and cell death by targeting microtubules. From screening a large panel of anti-FRα monoclonal antibodies, we selected the humanized antibody M9346A as the best antibody for targeted delivery of a maytansinoid payload into FRα-positive cells. We compared M9346A conjugates with various linker/maytansinoid combinations, and found that a conjugate, now denoted as IMGN853, with the N-succinimidyl 4-(2-pyridyldithio)-2-sulfobutanoate (sulfo-SPDB) linker and N(2')-deacetyl-N(2')-(4-mercapto-4-methyl-1-oxopentyl)-maytansine (DM4) exhibited the most potent antitumor activity in several FRα-expressing xenograft tumor models. The level of expression of FRα on the surface of cells was a major determinant in the sensitivity of tumor cells to the cytotoxic effect of the conjugate. Efficacy studies of IMGN853 in xenografts of ovarian cancer and non-small cell lung cancer cell lines and of a patient tumor-derived xenograft model demonstrated that the ADC was highly active against tumors that expressed FRα at levels similar to those found on a large fraction of ovarian and non-small cell lung cancer patient tumors, as assessed by immunohistochemistry. IMGN853 displayed cytotoxic activity against FRα-negative cells situated near FRα-positive cells (bystander cytotoxic activity), indicating its ability to eradicate tumors with heterogeneous expression of FRα. Together, these findings support the clinical development of IMGN853 as a novel targeted therapy for patients with FRα-expressing tumors.

Disulfide-linked antibody-maytansinoid conjugates: optimization of in vivo activity by varying the steric hindrance at carbon atoms adjacent to the disulfide linkage.

In this report, we describe the synthesis of a panel of disulfide-linked huC242 (anti-CanAg) antibody maytansinoid conjugates (AMCs), which have varying levels of steric hindrance around the disulfide bond, in order to investigate the relationship between stability to reduction of the disulfide linker and antitumor activity of the conjugate in vivo. The conjugates were first tested for stability to reduction by dithiothreitol in vitro and for plasma stability in CD1 mice. It was found that the conjugates having the more sterically hindered disulfide linkages were more stable to reductive cleavage of the maytansinoid in both settings. When the panel of conjugates was tested for in vivo efficacy in two human colon cancer xenograft models in SCID mice, it was found that the conjugate with intermediate disulfide bond stability having two methyl groups on the maytansinoid side of the disulfide bond and no methyl groups on the linker side of the disulfide bond (huC242-SPDB-DM4) displayed the best efficacy. The ranking of in vivo efficacies of the conjugates was not predicted by their in vitro potencies, since all conjugates were highly active in vitro, including a huC242-SMCC-DM1 conjugate with a noncleavable linkage which showed only marginal activity in vivo. These data suggest that factors in addition to intrinsic conjugate potency and conjugate half-life in plasma influence the magnitude of antitumor activity observed for an AMC in vivo. We provide evidence that bystander killing of neighboring nontargeted tumor cells by diffusible cytotoxic metabolites produced from target cell processing of disulfide-linked antibody-maytansinoid conjugates may be one additional factor contributing to the activity of these conjugates in vivo.

Progress in immunoconjugate cancer therapeutics.

Advances in immunoconjugate technology have revitalized the "magic bullet" concept of immunotherapeutics for the treatment of cancer. The growing availability of "human" antibodies, the increased epitope repertoire due to genomics and proteomics efforts, and advances in the means of identification and production of tumor-specific antibodies have greatly increased the potential for cancer therapeutic opportunities. Furthermore, the realization that effector molecule potency must be sufficiently high to be effective at concentrations that might realistically be delivered to the tumor site on an antibody carrier has greatly spurred the fields of medicinal chemistry and radionuclide chelate chemistry to produce such molecules.