Zanidatamab, a novel bispecific antibody, for the treatment of locally advanced or metastatic HER2-expressing or HER2-amplified cancers: a phase 1, dose-escalation and expansion study.

BACKGROUND: HER2-targeted therapies have substantially improved outcomes for patients with HER2-positive breast and gastric or gastro-oesophageal junction cancers. Several other cancers exhibit HER2 expression or amplification, suggesting that HER2-targeted agents can have broader therapeutic impact. Zanidatamab is a humanised, bispecific monoclonal antibody directed against two non-overlapping domains of HER2. The aim of this study was to evaluate the safety and anti-tumour activity of zanidatamab across a range of solid tumours with HER2 expression or amplification. METHODS: This first-in-human, multicentre, phase 1, dose-escalation and expansion trial included patients aged 18 years and older, with a life expectancy of at least 3 months, with an Eastern Cooperative Oncology Group performance status of 0 or 1, and locally advanced or metastatic, HER2-expressing or HER2-amplified solid tumours of any kind who had received all available approved therapies. The primary objectives of part 1 were to identify the maximum tolerated dose, optimal biological dose, or recommended dose of zanidatamab; all patients were included in the primary analyses. Part 1 followed a 3 + 3 dose-escalation design, including different intravenous doses (from 5 mg/kg to 30 mg/kg) and intervals (every 1, 2, or 3 weeks). The primary objective of part 2 was to evaluate the safety and tolerability of zanidatamab monotherapy in solid tumours. This trial is registered with ClinicalTrials.gov (NCT02892123), and parts 1 and 2 of the trial are complete. Part 3 of the study evaluates the use of zanidatamab in combination with chemotherapy and is ongoing. FINDINGS: Recruitment took place between Sept 1, 2016, and March 13, 2021. In Part 1 (n=46), no dose-limiting toxicities were detected and the maximum tolerated dose was not reached. The recommended dose for part 2 (n=22 for biliary tract cancer; n=28 for colorectal cancer; and n=36 for other HER2-expressing or HER2-amplified cancers excluding breast or gastro-oesophageal cancers; total n=86) was 20 mg/kg every 2 weeks. The most frequent treatment-related adverse events in part 1 of the study were diarrhoea (24 [52%] of 46 patients; all grade 1-2) and infusion reactions (20 [43%] of 46 patients; all grade 1-2). The most frequent treatment-related adverse events in part 2 of the study were diarrhoea (37 [43%] of 86 patients; all grade 1-2 except for one patient) and infusion reactions (29 [34%] of 86 patients; all grade 1-2). A total of six grade 3 treatment-related adverse events were reported in four (3%) of 132 patients. In part 2, 31 (37%; 95% CI 27·0-48·7) of 83 evaluable patients had a confirmed objective response. There were no treatment-related deaths. INTERPRETATION: These results support that HER2 is an actionable target in various cancer histologies, including biliary tract cancer and colorectal cancer. Evaluation of zanidatamab continues in ongoing studies. FUNDING: Zymeworks.

Longitudinal assessment of neurocognitive function in people with relapsing multiple sclerosis initiating alemtuzumab in routine clinical practice: LEM-COG study results.

BACKGROUND: Alemtuzumab is effective in reducing relapse rate and disability, but limited data exist on its effect on cognitive function in relapsing multiple sclerosis (RMS). The present study assessed neurocognitive function and safety associated with alemtuzumab treatment in RMS. METHODS: This longitudinal, single-arm, prospective study included people with RMS (aged 25-55 years) who were treated with alemtuzumab in clinical practice in the United States of America and Canada. The first participant was enrolled in December 2016. The primary endpoint was the change from baseline to post-baseline (month [M] 12/24) in MS-COGnitive (MS-COG) composite score. Secondary endpoints included Paced Auditory Serial Addition Test (PASAT), Symbol Digit Modalities Test (SDMT), Brief Visuospatial Memory Test-Revised (BVMT-R), Selective Reminding Test (SRT), Controlled Oral Word Association Test (COWAT), and Automated Neuropsychological Assessment Metrics (ANAM) scores. Depression and fatigue were assessed using Hamilton Rating Scale-Depression (HAM-D) and Fatigue Severity Scale (FSS)/Modified Fatigue Impact Scale (MFIS), respectively. Magnetic resonance imaging (MRI) parameters were assessed when available. Safety was assessed throughout the study. Descriptive statistics were used for the pre-specified statistical analyses. Since the study was terminated early (November 2019) because of operational and resource difficulties, post hoc analyses for statistical inference were performed among participants who had a baseline value and at least one complete post-baseline assessment for cognitive parameters, fatigue, or depression. RESULTS: Of the 112 participants enrolled, 39 were considered as the primary analysis population at M12. At M12, a mean change of 0.25 (95% confidence interval [CI]: 0.04, 0.45; p = 0.0049; effect size [ES]: 0.39) was observed in the MS-COG composite score. Improvements were observed in processing speed (based on PASAT and SDMT; p < 0.0001; ES: 0.62), as well as in individual PASAT, SDMT and COWAT scores. An improvement was also noted in HAM-D (p = 0.0054; ES: -0.44), but not in fatigue scores. Among MRI parameters, decreases in burden of disease volume (BDV; ES: -0.12), new gadolinium-enhancing lesions (ES: -0.41) and newly active lesions (ES: -0.07) were observed at M12. About 92% of participants showed stable or improved cognitive status at M12. There were no new safety signals reported in the study. The most common adverse events (≥10% of participants) were headache, fatigue, nausea, insomnia, urinary tract infection, pain in extremity, chest discomfort, anxiety, dizziness, arthralgia, flushing, and rash. Hypothyroidism (3.7%) was the most frequent adverse event of special interest. CONCLUSION: The findings from this study suggest that alemtuzumab has a positive impact on cognitive function with significant improvements in processing speed and depression in people with RMS over a period of 12 months. The safety profile of alemtuzumab was consistent with previous studies.

Temporary sequestration of potassium by mitochondria in astrocytes.

Increases in extracellular potassium concentration ([K(+)](o)), which can occur during neuronal activity and under pathological conditions such as ischemia, lead to a variety of potentially detrimental effects on neuronal function. Although astrocytes are known to contribute to the clearance of excess K(+)(o), the mechanisms are not fully understood. We examined the potential role of mitochondria in sequestering K(+) in astrocytes. Astrocytes were loaded with the fluorescent K(+) indicator PBFI and release of K(+) from mitochondria into the cytoplasm was examined after uncoupling the mitochondrial membrane potential with carbonyl cyanide m-chlorophenylhydrazone (CCCP). Under the experimental conditions employed, transient applications of elevated [K(+)](o) led to increases in K(+) within mitochondria, as assessed by increases in the magnitudes of cytoplasmic [K(+)] ([K(+)](i)) transients evoked by brief exposures to CCCP. When mitochondrial K(+) sequestration was impaired by prolonged application of CCCP, there was a robust increase in [K(+)](i) upon exposure to elevated [K(+)](o). Blockade of plasmalemmal K(+) uptake routes by ouabain, Ba(2+), or a mixture of voltage-activated K(+) channel inhibitors reduced K(+) uptake into mitochondria. Also, reductions in mitochondrial K(+) uptake occurred in the presence of mito-K(ATP) channel inhibitors. Rises in [K(+)](i) evoked by brief applications of CCCP following exposure to high [K(+)](o) were also reduced by gap junction blockers and in astrocytes isolated from connexin43-null mice, suggesting that connexins also play a role in K(+) uptake into astrocyte mitochondria. We conclude that mitochondria play a key role in K(+)(o) handling by astrocytes.

Regulation of early neurite morphogenesis by the Na+/H+ exchanger NHE1.

The ubiquitously expressed Na(+)/H(+) exchanger NHE1 plays an important role in regulating polarized membrane protrusion and directional motility in non-neuronal cells. Using NGF-differentiated PC12 cells and murine neocortical neurons in vitro, we now show that NHE1 plays a role in regulating early neurite morphogenesis. NHE1 was expressed in growth cones in which it gave rise to an elevated intracellular pH in actively extending neurites. The NHE1 inhibitor cariporide reversibly reduced growth cone filopodia number and the formation and elongation of neurites, especially branches, whereas the transient overexpression of full-length NHE1, but not NHE1 mutants deficient in either ion translocation activity or actin cytoskeletal anchoring, elicited opposite effects. In addition, compared with neocortical neurons obtained from wild-type littermates, neurons isolated from NHE1-null mice exhibited reductions in early neurite outgrowth, an effect that was rescued by overexpression of full-length NHE1 but not NHE1 mutants. Finally, the growth-promoting effects of netrin-1, but not BDNF or IGF-1, were markedly reduced by cariporide in wild-type neocortical neurons and were not observed in NHE1-null neurons. Although netrin-1 failed to increase growth cone intracellular pH or Na(+)/H(+) exchange activity, netrin-1-induced increases in early neurite outgrowth were restored in NHE1-null neurons transfected with full-length NHE1 but not an ion translocation-deficient mutant. Collectively, the results indicate that NHE1 participates in the regulation of early neurite morphogenesis and identify a novel role for NHE1 in the promotion of early neurite outgrowth by netrin-1.

Expression of connexins in embryonic mouse neocortical development.

During embryonic development, young neurons migrate from the ventricular zone to the cortical plate of the cerebral cortex. Disturbances in this neuronal migration have been associated with numerous diseases such as mental retardation, double cortex, Down syndrome, and epilepsy. One possible cause of these neuropathologies is an aberration in normal gap junctional communication. At least 20 connexin (Cx) genes encode gap junction proteins in mice and humans. A proper understanding of the role of specific connexins in the developing brain requires the characterization of their spatial and temporal pattern of expression. In the current study we performed all the experiments on mouse developing cortex at embryonic days (E) 14, 16, and 18, timepoints that are highly active with regard to cortical development. Using reverse transcription-polymerase chain reaction, Western blot analysis, and immunohistochemistry, we found that among the family of gap junction proteins, Cx26, Cx36, Cx37, Cx43, and Cx45 were expressed in the developing cortex of mice, Cx30 and Cx32 were absent, while Cx40 was expressed at a very low level. Our results demonstrate that Cx26 and Cx37 were evenly distributed in the cortical layers of developing brain, while Cx36 and Cx43 were more abundant in the ventricular zone and cortical plate. Cx45 distribution appeared to be more abundant at E18 compared to the other timepoints (E14 and E16). Thus, the present study provides identification and the distribution pattern for Cxs associated with cortical development during normal neuronal migration.

The complex of ciliary neurotrophic factor-ciliary neurotrophic factor receptor alpha up-regulates connexin43 and intercellular coupling in astrocytes via the Janus tyrosine kinase/signal transducer and activator of transcription pathway.

Cytokines regulate numerous cell processes, including connexin expression and gap junctional coupling. In this study, we examined the effect of ciliary neurotrophic factor (CNTF) on connexin43 (Cx43) expression and intercellular coupling in astrocytes. Murine cortical astrocytes matured in vitro were treated with CNTF (20 ng/ml), soluble ciliary neurotrophic factor receptor alpha (CNTFRalpha) (200 ng/ml), or CNTF-CNTFRalpha. Although CNTF and CNTFRalpha alone had no effect on Cx43 expression, the heterodimer CNTF-CNTFRalpha significantly increased both Cx43 mRNA and protein levels. Cx43 immunostaining correlated with increased intercellular coupling as determined by dye transfer analysis. By using the pharmacological inhibitor alpha-cyano-(3,4-dihydroxy)-N-benzylcinnamide (AG490), the increase in Cx43 was found to be dependent on the Janus tyrosine kinase/signal transducer and activator of transcription (JAK/STAT) pathway. Immunocytochemical analysis revealed that CNTF-CNTFRalpha treatment produced nuclear localization of phosphorylated STAT3, whereas CNTF treatment alone did not. Transient transfection of constructs containing various sequences of the Cx43 promoter tagged to a LacZ reporter into ROS 17/2.8 cells confirmed that the promoter region between -838 to -1693 was deemed necessary for CNTF-CNTFRalpha to induce heightened expression. CNTF-CNTFRalpha did not alter Cx30 mRNA levels, suggesting selectivity of CNTF-CNTFRalpha for connexin signaling. Together in the presence of soluble receptor, CNTF activates the JAK/STAT pathway leading to enhanced Cx43 expression and intercellular coupling.

Ciliary neurotrophic factor (CNTF) in combination with its soluble receptor (CNTFRalpha) increases connexin43 expression and suppresses growth of C6 glioma cells.

The loss of gap junctional intercellular communication has been proposedas playing a major role in the process of carcinogenesis. Most neoplastic cells, including C6 gliomas, express less connexins and have fewer gap junctions, reduced gap junctional intercellular communication, and increased growth rates compared with their nonneoplastic counterparts. The purpose of this study was to determine whether ciliary neurotrophic factor (CNTF) can be used to increase endogenous connexin43 levels, increase intercellular coupling, and retard the growth rate of C6 glioma cells. C6 cells were grown in serum-reduced medium (1% serum) and exposed to the following agents: vehicle (PBS), CNTF (20 ng/ml), CNTF soluble receptor (CNTFRalpha; 200 ng/ml), or Complex (CNTF + CNTFRalpha). Reverse transcription-PCR analysis indicated that C6 cells express CNTF mRNA but not CNTFRalpha mRNA. When cells were exposed to the above agents, only Complex caused an up-regulation of connexin43 protein (based on immunocytochemical and immunoblot analysis). Furthermore, Complex increased gap junctional coupling in C6 cells as noted by the passage of the gap junction permeable dye calcein. Finally, it was demonstrated that Complex-treatment reduces the growth rate of C6 cells compared with all of the other agents tested. Taken together, this study has demonstrated that CNTF in combination with its soluble receptor can increase connexin43 expression, increase gap junctional coupling, and reduce the in vitro proliferation of C6 glioma cells.

Blocked gap junctional coupling increases glutamate-induced neurotoxicity in neuron-astrocyte co-cultures.

Gap junctional communication is likely one means by which neurons can endure glutamate cytotoxicity associated with CNS insults (i.e. ischemia). To examine this neuroprotective role of gap junctions, we employed gap junctional blockers to neuronal and astrocytic co-cultures during exposure to a high concentration of extracellular glutamate. Co-cultures were treated with the blocking agents carbenoxolone (CBX; 25 microM), 18alpha-glycyrrhetinic acid (AGA; 10 microM), vehicle or the inactive blocking analogue glycyrrhizic acid (GZA; 25 microM). Twenty-four hours following the insult, cell mortality was analyzed and quantified by the release of lactate dehydrogenase (LDH) into the media, the cells' inability to exclude propidium iodide, and terminal dUTP nick end labeling (TUNEL). Measurement of LDH release revealed that the glutamate insult was detrimental to the co-cultures when gap junctions were blocked with CBX and AGA. Based on propidium iodide and TUNEL labeling, the glutamate insult caused significant cell death compared to sham vehicle and mortality was amplified in the presence of CBX and AGA. Since blockers were not themselves toxic and did not affect astrocytic uptake of glutamate, it is likely that blocked gap junctions lead to the increased glutamate cytotoxicity. These findings support the hypothesis that gap junctions play a neuroprotective role against glutamate cytotoxicity.

Co-administration of ciliary neurotrophic factor with its soluble receptor protects against neuronal death and enhances neurite outgrowth.

Attempts to promote neuronal survival and repair with ciliary neurotrophic factor (CNTF) have met with limited success. The variability of results obtained with CNTF may, in part, reflect the fact that some of the biological actions of the cytokine are mediated by a complex formed between CNTF and its specific receptor, CNTFRalpha, which exists in both membrane-bound and soluble forms. In this study, we compared the actions of CNTF alone and CNTF complexed with soluble CNTFRalpha (hereafter termed "Complex") on neuronal survival and growth. Although CNTF alone produced limited effects, Complex protected against glutamate-mediated excitotoxicity via gap junction-dependent and -independent mechanisms. Further examination revealed that only Complex promoted neurite outgrowth. Differential gene expression analysis revealed that, compared with CNTF alone, Complex differentially regulates several neuroprotective and neurotrophic genes. Collectively, these findings indicate that CNTF exerts more robust effects on neuronal survival and growth when applied in combination with its soluble receptor.

CCN3 (NOV) interacts with connexin43 in C6 glioma cells: possible mechanism of connexin-mediated growth suppression.

Many tumor cells exhibit aberrant gap junctional intercellular communication, which can be restored by transfection with connexin genes. We have previously discovered that overexpression of connexin43 (Cx43) in C6 glioma cells not only reduces proliferation but also leads to production of soluble growth-inhibitory factors. We identified that several members of the CCN (Cyr61/connective tissue growth factor/nephroblastoma-overexpressed) family are up-regulated following Cx43 expression, including CCN3 (NOV). We now report evidence for an association between CCN3 and Cx43. Western blot analysis demonstrated that the 48-kDa full-length CCN3 protein was present in the lysate and conditioned medium of growth-suppressed C6-Cx43 cells, as well as primary astrocytes, but not in C6 parental and human glioma cells. Immunocytochemical examination of CCN3 revealed diffuse localization in parental C6 cells, whereas transfection of C6 cells with Cx43 (C6-Cx43) or with a modified Cx43 tagged to green fluorescent protein on its C terminus (Cx43-GFP) resulted in punctate staining, suggesting that CCN3 co-localizes with Cx43 in plaques at the plasma membrane. In cells expressing a C-terminal truncation of Cx43 (Cx43Delta244-382), this co-localization was lost. Glutathione S-transferase pull-down assay and co-immunoprecipitation demonstrated that CCN3 was able to physically interact with Cx43. In contrast, CCN3 was not found to associate with Cx43Delta244-382. Similar experiments revealed that CCN3 did not co-localize or associate with other connexins, including Cx40 or Cx32. Taken together, these data support an interaction of CCN3 with the C terminus of Cx43, which could play an important role in mediating growth control induced by specific gap junction proteins.