Abstract 4227: NL-201, a de novo agonist of IL-2 and IL-15 receptors, demonstrates antitumor activity in preclinical B cell lymphoma models

NL-201 is a computationally-designed IL-2/IL-15 cytokine mimetic under investigation in a phase 1 clinical trial for patients with solid tumors. This de novo protein signals through the IL-2Rβ/ɣ complex in an IL-2Rα-independent fashion, supporting immune function of both T cells and natural killer (NK) cells. In syngeneic tumor models of solid tumors, NL-201 demonstrates marked antitumor activity through multiple mechanisms of action, including upregulation of granzyme B in cytotoxic CD8+ T cells and NK cells. Here, we further explored the therapeutic potential of NL-201 in preclinical models of B cell malignancies. In cell-based studies, NL-201 augmented antibody-dependent cellular cytotoxicity (ADCC) of Toledo DLBCL (diffuse large B cell lymphoma) cells incubated with human NK cells and CD20 antibodies. Importantly, direct activation by NL-201 was specific to NK cells and did not impact STAT5 phosphorylation nor proliferation of the tested malignant cells. The administration of NL-201 monotherapy in mice bearing A20 B cell lymphoma syngeneic tumors yielded robust inhibition of tumor growth. Tumor xenografts from implanted Pfeiffer cells have also been evaluated to understand the activity of NL-201 in a model closely resembling DLBCL physiology. In summary, NL-201 is active as a single agent and in combination with CD20-targeted therapies in vitro, as well as demonstrating monotherapy activity in in vivo preclinical models of B cell malignancies as well as in combination with checkpoint inhibitors. The NL-201 enhancement of cytotoxicity by CD8+ T cells and NK cells supports additional exploration aimed at optimizing combinatorial approaches. These findings will inform the design of planned clinical studies with NL-201 in patients with B-cell lymphomas and other hematological malignancies.

Citation Format: Justin Huard, Christie Mortales, Alex Chen, Ryan Swanson, Carl Walkey, Bill Arthur. NL-201, a de novo agonist of IL-2 and IL-15 receptors, demonstrates antitumor activity in preclinical B cell lymphoma models [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 4227.

Abstract 1766: SGN-ALPV a novel, investigational vedotin ADC demonstrates highly effective targeting of oncofetal phosphatases ALPP and ALPPL2 in preclinical models

Antibody-drug conjugates (ADC) leverage the specificity of antibodies to direct the delivery of potent cytotoxic agents to cancer cells. To fully leverage this specificity, targets with significant differential tumor versus normal tissue expression are ideal for ADC development. Placental alkaline phosphatases, ALPP and ALPPL2, are proteins present during fetal development but are found in several tumor types, making them an attractive ADC target. These cell membrane-attached phosphatases form homo- and heterodimers and play key roles in nucleotide recycling. SGN-ALPV is a novel investigational vedotin ADC comprised of a humanized IgG1 monoclonal antibody conjugated to the microtubule disrupting agent monomethyl auristatin E (MMAE) via a protease-cleavable peptide linker that has been clinically validated in multiple ADC programs. Here we characterize the target antigens, ALPP and ALPPL2, and evaluate SGN-ALPV antitumor activity in preclinical models. Immunohistochemistry and genomic data mining showed that ALPP and ALPPL2 have a highly restricted normal tissue expression yet high expression in several solid tumor types including ovarian, endometrial, germ cell, non-small cell lung and gastric carcinomas. Importantly, normal tissue expression is restricted to placenta and reproductive tissue, with low levels in lung tissue. SGN-ALPV utilizes a humanized antibody, h12F3, that is highly specific for both human and cynomolgus monkey ALPP and ALPPL2 proteins, but not other related phosphatases. In vitro, upon binding to SGN APLV, the antigens, ALPP and ALPPL2, are internalized to lysosomal vesicles releasing the MMAE payload, whose cytotoxic features drive mitotic arrest, apoptosis, and the induction of immunogenic cell death. Additionally, SGN-ALPV mediates antibody dependent cellular cytotoxicity (ADCC) and antibody-dependent cellular phagocytosis (ADCP) in vitro but lacks complement-dependent cytotoxicity. In preclinical studies, SGN-ALPV exhibits robust antitumor activity in cell line- and patient-derived xenograft models of ovarian, lung, pancreatic, and gastric carcinoma including models with both homogenous and heterogeneous expression of ALPP and ALPPL2, consistent with robust bystander activity of vedotin ADCs. Although, the contribution of ADCC and ADCP in vivo is currently unknown, it is expected that the antitumor activity of SGN-ALPV is mediated by MMAE cytotoxicity. SGN-ALPV was well tolerated in non-human primates (NHP) and exhibited linear pharmacokinetic characteristics, with a toxicity profile consistent with other vedotin-based ADCs. In summary, differential expression of ALPP and ALPPL2 in the tumor versus normal tissue, antibody specificity, antitumor activity, and tolerability of SGN-ALPV provide a strong rationale for the initiation of a planned first-in-human Phase 1 clinical study.

Citation Format: Sarah Anderson, Nanna Hansen, Robert Lawrence, Aroon T. Chande, David Ortiz, Christopher Carosino, Esther Trueblood, Nicole Stevens, Kerry Klussman, Angela Epp, Bill Arthur, Shyra Gardai, Hector Rincon. SGN-ALPV a novel, investigational vedotin ADC demonstrates highly effective targeting of oncofetal phosphatases ALPP and ALPPL2 in preclinical models [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 1766.

Abstract 835: Novel framework for quantifying synergy in high-throughput drug combination cytotoxicity experiments

Combination therapies are a cornerstone of cancer treatment, enabling a strategy of engaging multiple mechanisms of action. The in vitro testing of drug combinations is therefore a key step in drug discovery, and plate-based assays and robotics now allow for high-throughput cytotoxicity experiments that test combinations at doses diluted at high resolution. While additivity models such as Bliss, Loewe and Highest Single Agent (HSA) are well-established for gauging the synergy or antagonism of combinations, new frameworks are required for incorporating these models in the context of hundreds of experiments testing dozens of dose combinations per experiment. We have developed a framework that compares observed cytotoxicity results against the predictions from additivity models on a dose-by-dose basis across an entire matrix of dose combinations. Visualizations readily highlight any synergistic or antagonistic deviations from additivity. Statistical tests are then performed using 3x3 blocks of adjacent combinations. Such an approach mutes the effects of outliers and rewards consistency of activity in nearby doses. To capture the overall trend in an experiment and to facilitate comparisons across multiple experiments, we propose a summary metric, TSDA (total significant deviation from additivity) that takes into account both the absolute deviations from additivity and their statistical significance. Generally, positive values of TSDA indicate overall synergy, while negative values indicate overall antagonism. Null distributions for TSDA have been generated using simulations of sham experiments (same drug for both axes in a combination). We have applied this framework to over 1500 individual combination experiments spanning a range of cell lines and therapeutic mechanisms. The framework has been used to successfully guide follow-up in vivo experiments and to inform clinical plans.

Citation Format: Robert Thurman, Bill Arthur. Novel framework for quantifying synergy in high-throughput drug combination cytotoxicity experiments [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 835.

Identical and Nonidentical Twins: Risk and Factors Involved in Development of Islet Autoimmunity and Type 1 Diabetes

OBJECTIVE

There are variable reports of risk of concordance for progression to islet autoantibodies and type 1 diabetes in identical twins after one twin is diagnosed. We examined development of positive autoantibodies and type 1 diabetes and the effects of genetic factors and common environment on autoantibody positivity in identical twins, nonidentical twins, and full siblings.

RESEARCH DESIGN AND METHODS

Subjects from the TrialNet Pathway to Prevention Study (N = 48,026) were screened from 2004 to 2015 for islet autoantibodies (GAD antibody [GADA], insulinoma-associated antigen 2 [IA-2A], and autoantibodies against insulin [IAA]). Of these subjects, 17,226 (157 identical twins, 283 nonidentical twins, and 16,786 full siblings) were followed for autoantibody positivity or type 1 diabetes for a median of 2.1 years.

RESULTS

At screening, identical twins were more likely to have positive GADA, IA-2A, and IAA than nonidentical twins or full siblings (all P < 0.0001). Younger age, male sex, and genetic factors were significant factors for expression of IA-2A, IAA, one or more positive autoantibodies, and two or more positive autoantibodies (all P ≤ 0.03). Initially autoantibody-positive identical twins had a 69% risk of diabetes by 3 years compared with 1.5% for initially autoantibody-negative identical twins. In nonidentical twins, type 1 diabetes risk by 3 years was 72% for initially multiple autoantibody-positive, 13% for single autoantibody-positive, and 0% for initially autoantibody-negative nonidentical twins. Full siblings had a 3-year type 1 diabetes risk of 47% for multiple autoantibody-positive, 12% for single autoantibody-positive, and 0.5% for initially autoantibody-negative subjects.

CONCLUSIONS

Risk of type 1 diabetes at 3 years is high for initially multiple and single autoantibody-positive identical twins and multiple autoantibody-positive nonidentical twins. Genetic predisposition, age, and male sex are significant risk factors for development of positive autoantibodies in twins.

Development of a High-Throughput Gene Expression Screen for Modulators of RAS-MAPK Signaling in a Mutant RAS Cellular Context

The RAS-MAPK pathway controls many cellular programs, including cell proliferation, differentiation, and apoptosis. In colorectal cancers, recurrent mutations in this pathway often lead to increased cell signaling that may contribute to the development of neoplasms, thereby making this pathway attractive for therapeutic intervention. To this end, we developed a 26-member gene signature of RAS-MAPK pathway activity utilizing the Affymetrix QuantiGene Plex 2.0 reagent system and performed both primary and confirmatory gene expression-based high-throughput screens (GE-HTSs) using KRAS mutant colon cancer cells (SW837) and leveraging a highly annotated chemical library. The screen achieved a hit rate of 1.4% and was able to enrich for hit compounds that target RAS-MAPK pathway members such as MEK and EGFR. Sensitivity and selectivity performance measurements were 0.84 and 1.00, respectively, indicating high true-positive and true-negative rates. Active compounds from the primary screen were confirmed in a dose-response GE-HTS assay, a GE-HTS assay using 14 additional cancer cell lines, and an in vitro colony formation assay. Altogether, our data suggest that this GE-HTS assay will be useful for larger unbiased chemical screens to identify novel compounds and mechanisms that may modulate the RAS-MAPK pathway.

Abstract 3694: Relationship between in vivo antitumor activity of ADC and payload release in preclinical models

Antibody-drug conjugates (ADC) deliver cytotoxic payloads to target cells via receptor-mediated internalization. We have demonstrated that SGN-35 (cAC10-vcMMAE) binds to CD30 on target cells and releases intracellular monomethyl auristatin E (MMAE) in vitro, contributing to potent killing of CD30+ cells. Using a set of auristatin-based ADCs, we evaluated whether the intratumoral concentration of the released payload is a predictive indicator of antitumor activity in preclinical models.

We first treated CD30+, anaplastic large cell lymphoma (ALCL) Karpas 299 tumors with SGN-35 or a non-binding control ADC (IgG-vcMMAE). The plasma ADC and MMAE PK measurements were similar in SGN-35 and IgG-vcMMAE treated tumor-bearing animals. In contrast, SGN-35 generated 5-fold greater intratumoral MMAE exposure than IgG-vcMMAE, which correlated with tumor regression observed in the SGN-35- treated group.

We then examined the relationship between released MMAE and in vitro cytotoxicity by targeting different receptors expressed on the same cells. The lymphoma cell line L82 expresses CD30, CD70, and CD71 receptors. Although auristatin-based ADCs targeting each of these targets has a different IC50, the intracellular MMAE was similar when 50% growth inhibition was achieved (approximately 200 nM). In vivo, CD30, CD70, or CD71-directed ADCs demonstrated similar antitumor activity for a given dose level (0.5, 1, or 3 mg/kg). Concordantly, equal intratumoral MMAE concentrations were observed for a given dose level, regardless of the antigen target.

The cell permeable MMAE has been shown to mediate bystander killing in vitro. To evaluate whether intratumoral MMAE mediates bystander killing in vivo, an admixed tumor model consisting CD30+ and CD30- Karpas 299 cells was treated with SGN-35. As predicted, both CD30+ and CD30- tumor cells were killed, presumably due to intratumoral diffusion of MMAE across cell membranes. In contrast, a conjugate with a highly polar form of auristatin (MMAF) was unable to kill the CD30-negative cell population of the admixed tumors.

These preclinical results provide evidence that the concentration of released MMAE within the tumor correlates with the ADC antitumor activity in vitro and in vivo. Moreover, the in vivo bystander activity of MMAE may improve utility of this chemotype in tumors with heterogeneous antigen expression.

Citation Format: Fu Li, Xinqun Zhang, Kim Emmerton, Mechthild Jonas, Jocelyn Setter, Bill Arthur, Nicole Okeley, Robert Lyon, Dennis Benjamin, Che-Leung Law. Relationship between in vivo antitumor activity of ADC and payload release in preclinical models. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3694. doi:10.1158/1538-7445.AM2014-3694

Abstract 1986: RAS signaling is the key factor determining differential response to PI3K and MAPK targeting compounds in a panel of breast cancer cell lines

We have tested PI3K and MAPK targeting compounds in a panel of 69 breast cancer cell lines. Following the molecular stratification of breast cancer tumors, we have used ER and HER2 biomarkers to stratify cell lines into HER2 positive (HER2+), ER positive (ER+), and triple negative (TN; ER-, PR- and HER2-) subgroups. Both gene expression and response to compounds showed significant differences among the subtypes. Response to mTOR and AKT inhibition was the greatest in ER+ and HER2+ groups (86%, 85% for mTORi and 64%, 77% for AKTi response rates, respectively), whereas TN cell lines showed preferential sensitivity to MEK inhibition (30%). The combination of AKT plus MEK and mTOR plus MEK inhibitors showed synergy in TN tumors (56% and 80% response rates, respectively), particularly in the epithelial subgroup. We believe that RAS pathway deregulation, as reported by a gene expression signature of RAS activation, is the key latent variable that explains the difference in responses. This conclusion is based on pathway activation differences between subtypes. We observe that the TN group has both elevated PI3K and MAPK signaling, evident by high levels of RAS, pERK, and pMEK signatures, whereas the ER+/GGI+ group only has high levels of PI3K signaling. Thus, mTOR, AKT, or MEK alone is insufficient to inhibit the TN lines, whereas the combos are very effective. Finally, we have assessed the prevalence of the EMT and RAS signatures across subtypes of breast tumors. Similar to cell lines, the RAS signature is markedly higher in TN compared to ER+/GGI+ and, to a lesser extent, compared to HER2+ tumors. The EMT signature on the other hand is not significantly different among subtypes. This would suggest that the response patterns observed in ER+/GGI+ and TN/E subtypes of this breast panel will be applicable to a substantial subpopulation of breast tumors (∼38%). Importantly, these breast subtypes represent the largest unmet need and are a high priority for the clinical oncology.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1986.

Horizontal gaze palsy with progressive scoliosis can result from compound heterozygous mutations in ROBO3

BACKGROUND

Horizontal gaze palsy with progressive scoliosis (HGPPS) is an autosomal recessive disorder characterised by congenital absence of horizontal gaze, progressive scoliosis, and failure of the corticospinal and somatosensory axon tracts to decussate in the medulla. We previously reported that HGPPS patients from consanguineous pedigrees harbour homozygous mutations in the axon guidance molecule ROBO3.

METHODS

We now report two sporadic HGPPS children of non-consanguineous parents who harbour compound heterozygous mutations in ROBO3. The mother of one of the children also had scoliosis DNA was extracted from a blood sample from each participant using a standard protocol, and the coding exons of ROBO3 were amplified and sequenced as previously described.

RESULTS

Each patient harboured two unique heterozygous mutations in ROBO3, having inherited one mutation from each parent.

CONCLUSIONS

HGPPS can result from compound heterozygous mutations. More comprehensive examinations of parents and siblings of HGPPS patients are required to determine if the incidence of scoliosis in individuals harbouring heterozygous ROBO3 mutations is greater than in the general population.

Attitudes toward speech disorders: sampling the views of Cantonese-speaking Americans

Speech-language pathologists who serve clients from cultural backgrounds that are not familiar to them may encounter culturally influenced attitudinal differences. A questionnaire with statements about 4 speech disorders (dysfluency, cleft pallet, speech of the deaf, and misarticulations) was given to a focus group of Chinese Americans and a comparison group of non-Chinese Americans. The focus group was much more likely to believe that persons with speech disorders could improve their own speech by "trying hard," was somewhat more likely to say that people who use deaf speech and people with cleft palates might be "emotionally disturbed," and generally more likely to view deaf speech as a limitation. The comparison group was more pessimistic about stuttering children's acceptance by their peers than was the focus group. The two subject groups agreed about other items, such as the likelihood that older children with articulation problems are "less intelligent" than their peers.

Acute human trial of the floating mass transducer

Five patients underwent acute implantation of the Floating Mass Transducer (FMT) to evaluate the ability of the FMT to produce measurable auditory thresholds when temporarily placed in the middle ears of patients undergoing routine stapedotomy procedures. The FMT was placed on the long process of the incus in an inferior position, as is planned for clinical application, and in two additional positions. The ability of the FMT to produce measurable auditory thresholds was demonstrated in all patients. Results were affected by the lack of a healing period, the presence of a fixed stapes and an open middle ear space, and patient sedation.

Endogenously inhibited protein kinase C in transgenic Drosophila embryonic neuroblasts down regulates the outgrowth of type I and II processes of cultured mature neurons

Embryonic neurons were cultured from transgenic Drosophila melanogaster expressing a highly specific pseudosubstrate inhibitor of protein kinase C (PKC). Flies homozygous for this transgene, which is under the control of the yeast UAS promoter, were crossed to flies homozygous for the yeast heat shock inducible transcription factor GAL 4. Following heat shock, the progeny express the pseudosubstrate inhibitor at high levels. This strategy, which has the advantage of avoiding the non-specific effects of drugs, was used to study the role of PKC in process growth of cultured, differentiating neuroblasts. An external gold particle labeling procedure using a cell surface antigen expressed by mature neurons and processes was used to visualize neuronal processes directly in the scanning electron microscope. We observed that cell cultures expressing a low concentration of the pseudosubstrate inhibitor showed a significant decrease in the number of type I and II processes as compared to control cultures, while the proportions of neuroblasts, ganglion mother cells (GMCs), and mature neurons in the clusters were little affected.

Body composition in anorexia nervosa - changes with treatment, determinants and techniques

Body fat, total body water and totally body nitrogen were estimated twice before and after refeeding in 32 patients with anorexia nervosa. Body composition was estimated once in 29 normal controls using the techniques of anthropometry, impedance and IVNCA. The influence of weight gain and other variables, ie psychological status, biochemical parameters, exercise and dietary composition, on protein repletion was examined. Methods of assessment of body composition were compared. The results demonstrated that in anorexia nervosa patients, protein was more completely replenished than fat when patients had reached 85% of average body weight for height and age. Weight gain was the only determinant of protein gain. There was no correlation with psychological, biochemical or exercise status nor with dietary composition. Direct methods, ie deuterium dilution and IVNCA, were shown to be preferable in determination of body composition in anorexia nervosa.

Excessive physical activity in dieting disorder patients: proposals for a supervised exercise program

A relationship between starvation and hyperactivity has been observed in animal models, in experiments with human subjects, and in dieting disorder patients. Since the earliest descriptions of anorexia nervosa, excessive physical activity has figured prominently as a symptom of the illness, yet little attention has been directed towards this phenomenon. The aims of this paper are to review the published literature, to report our experience of the role of physical overactivity in the clinical presentation of dieting disorders, to discuss its implications for treatment, and to propose a supervised exercise program by which overactivity may be addressed specifically in the treatment of these patients.

Protein repletion and treatment in anorexia nervosa

Body fat and total body nitrogen (TBN) were quantified before and after refeeding in 32 female anorexia nervosa patients and in 29 matched control subjects by using the techniques of anthropometry and in vivo neutron-capture analysis (IVNCA). Mean body weight of patients (mean body mass index; BMI, in kg/m2), 15.4 +/- 1.3, was 72.7% of that of control subjects, increasing to 89.8% of mean weight of control subjects after refeeding (mean BMI 19.0 +/- 1.2). Mean BMI of control subjects was 21.6 +/- 2.7. Compared with the control group, patients' nitrogen was initially depleted by 24.5%, increased by 18.4%, but remained 10.6% below control values (P < 0.001). Body fat was depleted by 58.4%, increased by 89.7%, but remained 21.8% below control values (P < 0.001). Thus, despite a greater initial depletion and subsequently a greater net gain, body fat remained relatively more depleted after treatment than did nitrogen and protein. Anorexia nervosa patients were shown to readily replenish protein during nutritional rehabilitation.

Evidence for an integration theory of visual masking

When letters are superimposed upon a pattern of black and white squares, they are easier to identify when the pattern is regular than when it is random. If backward masking consists of the superimposition of a masking pattern upon the decaying visual trace of a target display, a regular pattern should be less effective as a backward mask than a random pattern. This was found to be so for both multiple-letter and single-letter displays. This result is predicted by an integration theory of visual masking but not by an interruption theory.