In vivo activity of the second-generation proteasome inhibitor ixazomib against pediatric T-cell acute lymphoblastic leukemia xenografts

The overall survival rate of patients with T-cell acute lymphoblastic leukemia (T-ALL) is now 90%, although patients with relapsed T-ALL face poor prognosis. The ubiquitin-proteasome system maintains normal protein homeostasis, and aberrations in this pathway are associated with T-ALL. Here we demonstrate the in vitro and in vivo activity of ixazomib, a second-generation orally available, reversible, and selective proteasome inhibitor against pediatric T-ALL cell lines and patient-derived xenografts (PDXs) grown orthotopically in immunodeficient NOD.Cg-PrkdcscidIL2rgtm1Wjl/SzJAusb (NSG) mice. Ixazomib was highly potent in vitro, with half-maximal inhibitory concentration (IC50) values in the low nanomolar range. As a monotherapy, ixazomib significantly extended mouse event-free survival of five out of eight T-ALL PDXs in vivo.

In vivo activity of the dual SYK/FLT3 inhibitor TAK-659 against pediatric acute lymphoblastic leukemia xenografts

BACKGROUND

While children with acute lymphoblastic leukemia (ALL) experience close to a 90% likelihood of cure, the outcome for certain high-risk pediatric ALL subtypes remains dismal. Spleen tyrosine kinase (SYK) is a prominent cytosolic nonreceptor tyrosine kinase in pediatric B-lineage ALL (B-ALL). Activating mutations or overexpression of Fms-related receptor tyrosine kinase 3 (FLT3) are associated with poor outcome in hematological malignancies. TAK-659 (mivavotinib) is a dual SYK/FLT3 reversible inhibitor, which has been clinically evaluated in several other hematological malignancies. Here, we investigate the in vivo efficacy of TAK-659 against pediatric ALL patient-derived xenografts (PDXs).

METHODS

SYK and FLT3 mRNA expression was quantified by RNA-seq. PDX engraftment and drug responses in NSG mice were evaluated by enumerating the proportion of human CD45+ cells (%huCD45+ ) in the peripheral blood. TAK-659 was administered per oral at 60 mg/kg daily for 21 days. Events were defined as %huCD45+ ≥ 25%. In addition, mice were humanely killed to assess leukemia infiltration in the spleen and bone marrow (BM). Drug efficacy was assessed by event-free survival and stringent objective response measures.

RESULTS

FLT3 and SYK mRNA expression was significantly higher in B-lineage compared with T-lineage PDXs. TAK-659 was well tolerated and significantly prolonged the time to event in six out of eight PDXs tested. However, only one PDX achieved an objective response. The minimum mean %huCD45+ was significantly reduced in five out of eight PDXs in TAK-659-treated mice compared with vehicle controls.

CONCLUSIONS

TAK-659 exhibited low to moderate single-agent in vivo activity against pediatric ALL PDXs representative of diverse subtypes.

Abstract 14: The impact of genetic background on cancer phenotypes of mouse models

The laboratory mouse is the premier animal model system for in vivo studies of the genetic and genomic basis of cancer in humans. Although thousands of mouse models have been generated, finding relevant data and knowledge about these models is complicated by a general lack of compliance in the published literature with nomenclature and annotation standards for genes, alleles, mouse strains, and cancer types. The Mouse Models of Human Cancer database (MMHCdb; tumor.informatics.jax.org) is an expertly curated knowledgebase of cancer phenotypes reported for diverse types of mouse models of human cancer such as inbred mouse strains, genetically engineered mouse models (GEMMs), Patient Derived Xenografts (PDXs), and mouse genetic diversity panels (e.g., the Collaborative Cross). MMHCdb includes data on more than 60,000 mouse models for over 1200 tumor classifications curated from more than 25,000 peer-reviewed publications.

One of the primary goals of the MMHCdb is to highlight the impact of genetic background on the incidence and presentation of different tumor types in mice. The same allele on different backgrounds can result in very different cancer characteristics and, therefore, impact the appropriateness of a model for a specific research application. In MMHCdb, users can review the impact of genetic background on the frequency of spontaneous tumors for inbred mouse strains using an interactive table generated from different published and unpublished data sources. In addition, color-coded tabular summaries of individual papers are available that allow researchers to quickly assess how genetic background affects cancer phenotypes in the mouse models reported in a specific publication. We will highlight examples of how genetic background can profoundly change the types and frequencies of tumor types that can be expected in mouse models of human cancer.

MMHCdb is supported by NCI R01 CA089713

Citation Format: Dale A. Begley, Debra M. Krupke, Steven B. Neuhauser, Emily L. Jocoy, John P. Sundberg, Carol J. Bult. The impact of genetic background on cancer phenotypes of mouse models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 14.

The mouse models of human cancer database (MMHCdb)

The laboratory mouse has served for decades as an informative animal model system for investigating the genetic and genomic basis of cancer in humans. Although thousands of mouse models have been generated, compiling and aggregating relevant data and knowledge about these models is hampered by a general lack of compliance in the published literature with nomenclature and annotation standards for genes, alleles, mouse strains, and cancer types. The Mouse Models of Human Cancer database (MMHCdb; http://tumor.informatics.jax.org) is an expertly curated, comprehensive knowledgebase of diverse types of mouse models of human cancer including inbred mouse strains, genetically engineered mouse models (GEMMS), Patient Derived Xenografts (PDXs), and mouse genetic diversity panels such as the Collaborative Cross. The MMHCdb is a FAIR-compliant knowledgebase that enforces nomenclature and annotation standards and supports completeness and accuracy of searches for mouse models of human cancer and associated data. The resource facilitates the analysis of the impact of genetic background on the incidence and presentation of different tumor types and aids in the assessment of different mouse strains as models of human cancer biology and treatment response.

ACDA: implementation of an augmented drug synergy prediction algorithm

Motivation

Drug synergy prediction is approached with machine learning techniques using molecular and pharmacological data. The published Cancer Drug Atlas (CDA) predicts a synergy outcome in cell-line models from drug target information, gene mutations and the models' monotherapy drug sensitivity. We observed low performance of the CDA, 0.339, measured by Pearson correlation of predicted versus measured sensitivity on DrugComb datasets.

Results

We augmented the approach CDA by applying a random forest regression and optimization via cross-validation hyper-parameter tuning and named it Augmented CDA (ACDA). We benchmarked the ACDA's performance, which is 68% higher than that of the CDA when trained and validated on the same dataset spanning 10 tissues. We compared the performance of ACDA to one of the winning methods of the DREAM Drug Combination Prediction Challenge, the performance of which was lower than ACDA in 16 out of 19 cases. We further trained the ACDA on Novartis Institutes for BioMedical Research PDX encyclopedia data and generated sensitivity predictions for PDX models. Finally, we developed a novel approach to visualize synergy-prediction data.

Availability and implementation

The source code is available at https://github.com/TheJacksonLaboratory/drug-synergy and the software package at PyPI.

Supplementary information

Supplementary data are available at Bioinformatics Advances online.

A Genomically and Clinically Annotated Patient-Derived Xenograft Resource for Preclinical Research in Non-Small Cell Lung Cancer

Patient-derived xenograft (PDX) models are an effective preclinical in vivo platform for testing the efficacy of novel drugs and drug combinations for cancer therapeutics. Here we describe a repository of 79 genomically and clinically annotated lung cancer PDXs available from The Jackson Laboratory that have been extensively characterized for histopathologic features, mutational profiles, gene expression, and copy-number aberrations. Most of the PDXs are models of non-small cell lung cancer (NSCLC), including 37 lung adenocarcinoma (LUAD) and 33 lung squamous cell carcinoma (LUSC) models. Other lung cancer models in the repository include four small cell carcinomas, two large cell neuroendocrine carcinomas, two adenosquamous carcinomas, and one pleomorphic carcinoma. Models with both de novo and acquired resistance to targeted therapies with tyrosine kinase inhibitors are available in the collection. The genomic profiles of the LUAD and LUSC PDX models are consistent with those observed in patient tumors from The Cancer Genome Atlas and previously characterized gene expression-based molecular subtypes. Clinically relevant mutations identified in the original patient tumors were confirmed in engrafted PDX tumors. Treatment studies performed in a subset of the models recapitulated the responses expected on the basis of the observed genomic profiles. These models therefore serve as a valuable preclinical platform for translational cancer research.

SIGNIFICANCE

Patient-derived xenografts of lung cancer retain key features observed in the originating patient tumors and show expected responses to treatment with standard-of-care agents, providing experimentally tractable and reproducible models for preclinical investigations.

Abstract LB061: Evaluation of the in vivo efficacy of the B7-H3 targeting antibody-drug conjugate (ADC) DS7300a: A report fro the Pediatric Preclinical In Vivo Resting (PIVOT) program

Introduction: B7-H3 (encoded by the CD276 gene) is suggested to act as an immune checkpoint molecule and is highly expressed in some pediatric solid tumors. Monoclonal antibodies targeting B7-H3 (8H9 and MGA271) are well-tolerated but have demonstrated limited success in clinical trials. DS-7300a is a B7-H3 targeting ADC with a payload of DXd (an exatecan derivative that inhibits DNA topoisomerase I). DS-7300a has a drug-to-antibody ratio of 4 and it has shown promising early clinical activity in adults with advanced solid cancers (Johnson, Annals of Oncology 2021; 32:S583-S585).

Methods: Xenograft models for several pediatric cancer types were selected for preclinical testing of DS-7300a based on the high rates of B7-H3 expression in these cancers. Models were dosed at 10 mg/kg administered intravenously every other week for two doses (Q2wk x 2). Different experimental designs were used for efficacy testing. For rhabdomyosarcoma, Ewing sarcoma, Wilms tumor, and other pediatric solid tumors a single mouse trial (SMT) design with 40 models was used. A cohort design (N=10) was used for efficacy testing in 6 osteosarcoma models, 3 patient-derived orthotopic xenograft glioblastoma (PDOX) models, and 3 PDOX ependymoma models. For neuroblastoma models, 10 models (2 mice per model) were tested. To evaluate treatment efficacy, objective response measures based on changes in relative tumor volume were used (Houghton, Pediatr Blood Cancer 2007;49:928-940).

Results: As a single agent, DS-7300a induced a statistically significant prolongation of survival in 2 of 3 orthotopic glioblastoma and 1 of 3 ependymal tumor models. DS-7300a demonstrated high efficacy (maintained complete response, complete response, and partial response) in most non-CNS models tested: 17 of 21 rhabdomyosarcomas, 5 of 7 osteosarcomas, 7 of 10 neuroblastomas and 2 of 2 Wilms tumors. For Ewing sarcoma, most models were classified as progressive disease (9 of 15). For osteosarcoma models, the log cell kill per dose values ranged from 0.95 to 2.76 indicating high activity of the agent in these models. The activity for DS-7300a followed the general pattern of protein and RNA expression levels for B7-H3/CD276 in the models, with Ewing sarcoma models showing lower expression compared to the other models.

Conclusions: DS-7300a shows tumor-regressing anticancer activity across a wide range of pediatric solid tumor models. The maintained complete remissions observed for osteosarcoma models are noteworthy, as this level of response is uncommon for these models and as osteosarcoma shows the highest B7-H3 expression among pediatric cancers. The high level of preclinical activity observed for DS-7300a combined with the promising early clinical activity observed for adult patients provide strong rationale for studying DS-7300a in children with B7-H3 expressing solid tumors.

Citation Format: Richard Gorlick, E. Anders Kolb, Yifei Wang, Peter Houghton, Raushan Kurmasheva, Yael Mosse, John Maris, Matthew Tsang, David Groff, Kateryna Krytska, Xiao-Nan Li, Yuchen Du, Jun Hasegawa, Nanae Izumi, Steven Neuhauser, Anuj Srivastava, Tim Stearns, Vivek Philip, Emily L. Jocoy, Jeff Chuang, Carol J. Bult, Beverly Teicher, Malcolm Smith. Evaluation of the in vivo efficacy of the B7-H3 targeting antibody-drug conjugate (ADC) DS7300a: A report fro the Pediatric Preclinical In Vivo Resting (PIVOT) program [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr LB061.

Dissecting the contribution of individual receptor subunits to the enhancement of N-methyl-d-aspartate currents by dopamine D1 receptor activation in striatum

Dopamine, via activation of D1 receptors, enhances N-methyl-d-aspartate (NMDA) receptor-mediated responses in striatal medium-sized spiny neurons. However, the role of specific NMDA receptor subunits in this enhancement remains unknown. Here we used genetic and pharmacological tools to dissect the contribution of NR1 and NR2A/B subunits to NMDA responses and their modulation by dopamine receptors. We demonstrate that D1 enhancement of NMDA responses does not occur or is significantly reduced in mice with genetic knock-down of NR1 subunits, indicating a critical role of these subunits. Interestingly, spontaneous and evoked α-amino-3-hydroxyl-5-methyl-4-isoxazole-propionic acid (AMPA) receptor-mediated responses were significantly enhanced in NR1 knock-down animals, probably as a compensatory mechanism for the marked reduction in NMDA receptor function. The NMDA receptor subunits NR2A and NR2B played differential roles in D1 modulation. Whereas genetic deletion or pharmacological blockade of NR2A subunits enhanced D1 potentiation of NMDA responses, blockade of NR2B subunits reduced this potentiation, suggesting that these regulatory subunits of the NMDA receptor counterbalance their respective functions. In addition, using D1 and D2 receptor EGFP-expressing mice, we demonstrate that NR2A subunits contribute more to NMDA responses in D1-MSSNs, whereas NR2B subunits contribute more to NMDA responses in D2 cells. The differential contribution of discrete receptor subunits to NMDA responses and dopamine modulation in the striatum has important implications for synaptic plasticity and selective neuronal vulnerability in disease states.

Dopamine modulation of excitatory currents in the striatum is dictated by the expression of D1 or D2 receptors and modified by endocannabinoids

Striatal medium-sized spiny neurons (MSSNs) receive glutamatergic inputs modulated presynaptically and postsynaptically by dopamine. Mice expressing the gene for enhanced green fluorescent protein as a reporter gene to identify MSSNs containing D1 or D2 receptor subtypes were used to examine dopamine modulation of spontaneous excitatory postsynaptic currents (sEPSCs) in slices and postsynaptic N-methyl-d-aspartate (NMDA) and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) currents in acutely isolated cells. The results demonstrated dopamine receptor-specific modulation of sEPSCs. Dopamine and D1 agonists increased sEPSC frequency in D1 receptor-expressing MSSNs (D1 cells), whereas dopamine and D2 agonists decreased sEPSC frequency in D2 receptor-expressing MSSNs (D2 cells). These effects were fully (D1 cells) or partially (D2 cells) mediated through retrograde signaling via endocannabinoids. A cannabinoid 1 receptor (CB1R) agonist and a blocker of anandamide transporter prevented the D1 receptor-mediated increase in sEPSC frequency in D1 cells, whereas a CB1R antagonist partially blocked the decrease in sEPSC frequency in D2 cells. At the postsynaptic level, low concentrations of a D1 receptor agonist consistently increased NMDA and AMPA currents in acutely isolated D1 cells, whereas a D2 receptor agonist decreased these currents in acutely isolated D2 cells. These results show that both glutamate release and postsynaptic excitatory currents are regulated in opposite directions by activation of D1 or D2 receptors. The direction of this regulation is also specific to D1 and D2 cells. We suggest that activation of postsynaptic dopamine receptors controls endocannabinoid mobilization, acting on presynaptic CB1Rs, thus modulating glutamate release differently in glutamate terminals projecting to D1 and D2 cells.

Morphological and electrophysiological characterization of abnormal cell types in pediatric cortical dysplasia

The mechanisms responsible for seizure generation in cortical dysplasia (CD) are unknown, but morphologically abnormal cells could contribute. We examined the passive and active membrane properties of cells from pediatric CD in vitro. Normal- and abnormal-appearing cells were identified morphologically by using infrared videomicroscopy and biocytin in slices from children with mild to severe CD. Electrophysiological properties were assessed with patch clamp recordings. Four groups of abnormal-appearing cells were observed. The first consisted of large, pyramidal cells probably corresponding to cytomegalic neurons. Under conditions that reduced the contribution of K(+) conductances, these cells generated large Ca(2+) currents and influx when depolarized. When these cells were acutely dissociated, peak Ca(2+) currents and densities were greater in cytomegalic compared with normal-appearing pyramidal neurons. The second group included large, nonpyramidal cells with atypical somatodendritic morphology that could correspond to "balloon" cells. These cells did not display active voltage- or ligand-gated currents and did not appear to receive synaptic inputs. The third group included misoriented and dysmorphic pyramidal neurons, and the fourth group consisted of immature-looking pyramidal neurons. Electrophysiologically, neurons in these latter two groups did not display significant abnormalities when compared with normal-appearing pyramidal neurons. We conclude that there are cells with abnormal intrinsic membrane properties in pediatric CD. Among the four groups of cells, the most abnormal electrophysiological properties were displayed by cytomegalic neurons and large cells with atypical morphology. Cytomegalic neurons could play an important role in the generation of epileptic activity.

Concurrent visual task effects on evoked and emitted auditory p300 in adolescents

Using an oddball stimulus presentation paradigm, the effects of divided attention on auditory P300s were studied. Auditory attention was either divided or focused, depending on the demands placed on subjects during the performance of a concomitantly presented visual task. Two types of auditory tasks were performed under each of the two auditory attention conditions. In one, subjects responded to infrequently presented high pitched tones (oddball stimuli). In the other they responded to the occasional omission of a stimulus in an otherwise rhythmically presented chain of stimuli. P300s and reaction times were recorded to both the rare tones and the omissions. The Sternberg visual memory task was used to manipulate the subject's auditory attention state. Subjects actively performed the Sternberg task during the divided auditory attention condition, whereas during the focused attention condition they were not required to respond to the visual stimuli. During focused auditory attention, evoked auditory P300s were both larger and faster than their emitted counterparts. During divided attention, auditory P300s were reduced in amplitude but latency was unaffected. Evoked auditory P300s showed evidence of containing P300a as well as P300b components, particularly when attention was shared with the visual task.