Sialyl-Tn serves as a potential therapeutic target for ovarian cancer

BACKGROUND

Ovarian cancer remains the deadliest of the gynecologic cancers in the United States. There have been limited advances in treatment strategies that have seen marked increases in overall survival. Thus, it is essential to continue developing and validating new treatment strategies and markers to identify patients who would benefit from the new strategy. In this report, we sought to further validate applications for a novel humanized anti-Sialyl Tn antibody-drug conjugate (anti-STn-ADC) in ovarian cancer.

METHODS

We aimed to further test a humanized anti-STn-ADC in sialyl-Tn (STn) positive and negative ovarian cancer cell line, patient-derived organoid (PDO), and patient-derived xenograft (PDX) models. Furthermore, we sought to determine whether serum STn levels would reflect STn positivity in the tumor samples enabling us to identify patients that an anti-STn-ADC strategy would best serve. We developed a custom ELISA with high specificity and sensitivity, that was used to assess whether circulating STn levels would correlate with stage, progression-free survival, overall survival, and its value in augmenting CA-125 as a diagnostic. Lastly, we assessed whether the serum levels reflected what was observed via immunohistochemical analysis in a subset of tumor samples.

RESULTS

Our in vitro experiments further define the specificity of the anti-STn-ADC. The ovarian cancer PDO, and PDX models provide additional support for an anti-STn-ADC-based strategy for targeting ovarian cancer. The custom serum ELISA was informative in potential triaging of patients with elevated levels of STn. However, it was not sensitive enough to add value to existing CA-125 levels for a diagnostic. While the ELISA identified non-serous ovarian tumors with low CA-125 levels, the sample numbers were too small to provide any confidence the STn ELISA would meaningfully add to CA-125 for diagnosis.

CONCLUSIONS

Our preclinical data support the concept that an anti-STn-ADC may be a viable option for treating patients with elevated STn levels. Moreover, our STn-based ELISA could complement IHC in identifying patients with whom an anti-STn-based strategy might be more effective.

Abstract 491: Melanoma patients with multi-Siglec ligands as profiled by HYDRA technology are refractory to PD1 blockade

PD1/PD-L1 and CTLA-4 checkpoint blockade have revolutionized cancer therapy and led to cures in metastatic melanoma, but most patients develop primary and acquired resistance to these therapies. Treating this refractory population requires the discovery of new immune escape mechanisms. Sialic acid–binding immunoglobulin-type lectins (Siglecs) are expressed on the majority of white blood cells of the immune system, play critical roles in immune cell signaling and serve as immune checkpoints to prevent unwanted immune responses. Sialic acid is a ligand for inhibitory Siglecs; hypersialyation is a hallmark of poor prognosis and is believed to help tumors escape from immune surveillance. However, the role of hypersialylation in resistance to immune checkpoint therapies remains unexplored. To study if hypersialylation drives immune escape in melanoma, we profiled the immunosuppressive sialoglycans using Siglec-based high-affinity sialoglycan-binding constructs called ‘HYDRAs'. The current study focuses on understanding Siglec-3, -7 and -9 sialoglycan ligand expression on tumors using the HYDRA-3, -7 and -9 platform, because these Siglecs are the major inhibitory Siglecs on both innate and adaptive immune cells among the fourteen Siglecs in humans. Serial sections from melanoma tumors and healthy tissues were stained with HYDRA-3, -7 or -9 and scored using the semi-qualitative H-score method by a blinded pathologist. HYDRA IHC on healthy and cancerous human tissues demonstrate unique binding patterns with melanomas having high signals for HYDRA-3, -7 and -9. A pre-treatment checkpoint inhibitor therapy cohort (n=53), which contained responders (n=30) and non-responders (n=23) to either aPD1 or aPD1 and aCTLA-4 combination therapy was further studied. Serial sections from each patient was stained with HYDRA-3, -7 or -9 and scored using the semi-qualitative H-score method by our blinded pathologist. Cutoffs were determined in an unbiased manner for each HYDRA individually and each possible HYDRA combination to obtain correlations with patient progression-free and overall survival. A significant tumor H-score cutoff of a combined HYDRA-3 and -7 correlated with poor outcomes. This HYDRA-3 and -7 cutoff did not correlate with other melanoma biomarkers such as BRAF-mutation, liver metastases, PD-L1, nor TILs, suggesting a unique biology independent of these markers. We discovered that melanoma patients with multi-Siglec ligands as profiled by HYDRAs tend to be resistant to PD-1 checkpoint blockade and can be candidates for novel treatments targeting the Siglec-Sialoglycan axis. A larger cohort and longitudinal study are currently underway to examine the Siglec-Sialoglycan axis of immunosuppression in melanoma and late-breaking results will be included in this poster.

Citation Format: Adam Petrone, Dennie T. Frederick, Jillian M. Prendergast, James Broderick, Karl Normington, Genevieve Boland, Li Peng. Melanoma patients with multi-Siglec ligands as profiled by HYDRA technology are refractory to PD1 blockade [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 491.

Abstract 387: Glycoproteomics as a powerful liquid biopsy-based predictor of checkpoint-inhibitor treatment response

Introduction: Protein glycosylation is the most abundant and most complex form of post-translational protein modification. Glycosylation profoundly affects protein structure, conformation, and function. The elucidation of the potential role of differential protein glycosylation as biomarkers has so far been limited by the technical complexity of generating and interpreting this information. We have recently established a novel, powerful platform that combines ultra-high-performance liquid chromatography coupled to triple quadrupole mass spectrometry with a proprietary machine learning and neural-network-based data processing engine that allows, for the first time, high-throughput, highly scalable interrogation of the glycoproteome.

Experimental Procedures: Using this platform we interrogated 413 individual glycopeptide (GP) signatures derived from 69 abundant serum proteins in pretreatment blood samples from a cohort of 36 individuals (11 females, 25 males, age range 28 to 90 years) with metastatic malignant melanoma treated either with nivolumab plus ipilimumab (12 patients) or pembrolizumab (24 patients). Progression-free survival (PFS) data with follow-up of up to 3.7 years (median: 0.8 years) were used as clinical endpoint phenotype against which the predictive power of differential abundance of GPs was assessed. PFS data were analyzed using Cox Proportional Hazards models, and Kaplan Meier curves were generated for GP markers that showed statistically significant differential abundances using an FDR-adjusted p-value of ≤0.1 as a cutoff.

Summary of Results: We identified 27 GPs with abundance differences at FDR p≤0.1, and among them 8 at p≤0.001. Using the latter 8 markers, we created a multivariable model for PFS by generating leave-one-out cross-validation (LOOCV) scores and determining an optimized cutoff value for these scores using Harrel's concordance index. Dichotomizing the LOOCV scores using this cutoff value demonstrated the model to yield a hazard ratio of 9.2 at a p-value of 10-5 for separating treatment responders and non-responders (70% vs. 0% PFS, respectively, at 18 months based on LOOCV score above/below cutoff), as compared to a hazard ratio of 1.5, p=0.5 for PDL1 expression. Conclusions: Our results indicate that glycoproteomics holds a strong promise as a response predictor to checkpoint inhibitor treatment that appears to significantly outperform other currently pursued biomarker approaches in this context.

Citation Format: Gege Xu, Rachel Rice, Hector Huang, Klaus Lindpaintner, Jillian M. Prendergast, Karl Normington, Dennie Frederick, Genevieve M. Boland, Daniel Serie. Glycoproteomics as a powerful liquid biopsy-based predictor of checkpoint-inhibitor treatment response [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 387.

Production of a mouse monoclonal IgM antibody that targets the carbohydrate Thomsen-nouveau cancer antigen resulting in in vivo and in vitro tumor killing

The construction of a tumor-associated carbohydrate antigen-zwitterionic polysaccharide conjugate, Thomsen-nouveau-polysaccharide A1 (Tn-PS A1, where Tn = D-GalpNAc), has led to the development of a carbohydrate binding monoclonal antibody named Kt-IgM-8. Kt-IgM-8 was produced via hybridoma from Tn-PS A1 hyperimmunized Jackson Laboratory C57BL/6 mice, splenocytes and the murine myeloma cell line Sp2/0Ag14 with subsequent cloning on methyl cellulose semi-solid media. This in-house generated monoclonal antibody negates binding influenced from peptides, proteins, and lipids and preferentially binds monovalent Tn antigen as noted by ELISA, FACS, and glycan array technologies. Kt-IgM-8 demonstrated in vitro and in vivo tumor killing against the Michigan Cancer Foundation breast cell line 7 (MCF-7). In vitro tumor killing was observed using an LDH assay that measured antibody-induced complement-dependent cytotoxicity and these results were validated in an in vivo passive immunotherapy approach using an MCF-7 cell line-derived xenograft model. Kt-IgM-8 is effective in killing tumor cells at 30% cytotoxicity, and furthermore, it demonstrated approximately 40% reduction in tumor growth in the MCF-7 model.

Abstract B28: Targeting the tumor-associated carbohydrate antigen STn with humanized anti-Sialyl-Tn monoclonal antibody-drug conjugates inhibits ovarian cancer tumor growth in vitro and in vivo

Ovarian cancer is the leading cause of death from gynecologic malignancies in the U.S. The current standard of care is tumor debulking followed by chemotherapy. This treatment results in approximately 70% of patients achieving an initial complete clinical response. However, many of these patients will unfortunately relapse with chemoresistant disease developing in part to the presence of cancer stem cells (CSCs) within the tumor. Indeed, ovarian CSCs have been identified and shown to be resistant to chemo- and radiotherapy. Cancer cell surface glycans, called tumor-associated carbohydrate antigens (TACAs), are a class of attractive cancer-specific targets found on the cell surface of many solid tumors. Siamab is targeting a glycan structure (Sialyl-Tn, STn) that is cancer-specific and a major reported constituent of two well-known CSC biomarkers, CD44 and MUC1, residing on both CSCs and mature malignant cells in some cancer types. Although CD44 and MUC1 are also present on normal tissue and normal stem cell surfaces, tumor and CSC specificity is conferred the presence of STn-glycosylated variants of these CSC markers and other cell surface proteins that are essentially absent from normal human tissues. Importantly, STn can be a component of CA-125 (MUC16), conferring additional specificity to this diagnostic marker for ovarian carcinoma. The elevated presence of STn in tumors is associated with metastatic disease, poor prognosis, and reduced overall survival. In addition, elevations in STn expression are linked to chemotherapy resistance and enable tumors to evade the host immune system. We have observed that STn levels are elevated in cancer cells following chemotherapy treatment in both in vitro and in vivo model systems and STn is present on specific subtype of tumor-infiltrating myeloid-derived suppressor cells. Both observations support the role of STn in tumor chemoresistance and immunomodulation. While attempts have been made to target STn clinically with a cancer vaccine, efficacy has been limited. Siamab has developed a unique immunotherapeutic solution aimed at eradicating human neoplasias by targeting both CSCs and bulk tumor to enable whole tumor killing. We have identified and humanized a panel of mouse monoclonal novel antibodies (Abs) that specifically target with high affinity the STn glycan independent of its carrier protein. These Abs are highly selective in binding assays demonstrating robust nanomolar EC50s, possess specificity on tissues as determined with neuraminidase treatment, and exhibit STn-specific glycan binding on Siamab’s proprietary glycan array. Antitumor efficacy was evaluated in vitro and in vivo utilizing humanized anti-STn antibody drug conjugated (ADC) material. Cell cytotoxicity was demonstrated in a panel of STn-expressing cell lines with low nanomolar IC50s. We confirmed that the decrease in proliferation in vitro can be translated to a reduction in tumor size in vivo, through a series of cell line and patient-derived ovarian cancer xenograft models. Inhibition of tumor progression were observed in all models, with complete regressions observed in some treatment arms. No significant weight loss was observed for any treatment groups, indicating the therapy was well tolerated by all the groups. A decrease in STn expression was noted in the tumors following treatment, indicating that we were hitting the target against which these Abs were generated. In addition, we have begun the development of both tissue- and serum-based biomarker assays utilizing these selective anti-STn Abs. Our data demonstrate that high-affinity, STn-selective humanized mAbs show promise as therapies for ovarian tumors, as well as tools for patient stratification and pharmacodynamic biomarker assessments.

Citation Format: Daniel T. Dransfield, Jillian M. Prendergast, David A. Eavarone, Rawan Nazer, Linah Al-Alem, Jenna Stein, Jeff Behrens, Bo Rueda. Targeting the tumor-associated carbohydrate antigen STn with humanized anti-Sialyl-Tn monoclonal antibody-drug conjugates inhibits ovarian cancer tumor growth in vitro and in vivo. [abstract]. In: Proceedings of the AACR Conference: Addressing Critical Questions in Ovarian Cancer Research and Treatment; Oct 1-4, 2017; Pittsburgh, PA. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(15_Suppl):Abstract nr B28.

Humanized anti-Sialyl-Tn antibodies for the treatment of ovarian carcinoma

The expression of Sialyl-Tn (STn) in tumors is associated with metastatic disease, poor prognosis, and reduced overall survival. STn is expressed on ovarian cancer biomarkers including CA-125 (MUC16) and MUC1, and elevated serum levels of STn in ovarian cancer patients correlate with lower five-year survival rates. In the current study, we humanized novel anti-STn antibodies and demonstrated the retention of nanomolar (nM) target affinity while maintaining STn antigen selectivity. STn antibodies conjugated to Monomethyl Auristatin E (MMAE-ADCs) demonstrated in vitro cytotoxicity specific to STn-expressing ovarian cancer cell lines and tumor growth inhibition in vivo with both ovarian cancer cell line- and patient-derived xenograft models. We further validated the clinical potential of these STn-ADCs through tissue cross-reactivity and cynomolgus monkey toxicity studies. No membrane staining for STn was present in any organs of human or cynomolgus monkey origin, and the toxicity profile was favorable and only revealed MMAE-class associated events with none being attributed to the targeting of STn. The up-regulation of STn in ovarian carcinoma in combination with high affinity and STn-specific selectivity of the mAbs presented herein warrant further investigation for anti-STn antibody-drug conjugates in the clinical setting.

Abstract 5625: Myeloid derived suppressor cells (MDSCs) express Sialyl Tn (STn) and are a therapeutic target for anti-STn antibody drug conjugates

Introduction: Myeloid derived suppressor cells (MDSCs) are functionally defined by their capacity to suppress T cell immunity; therefore inhibiting these cells is of great interest for immuno-oncology applications. STn, the sialylated version of the carbohydrate Tn antigen, is broadly expressed in human cancers such as breast, ovarian, bladder, cervical, colon, and lung and is rarely expressed in normal adult human tissues. The presence of STn in tumors is associated with metastatic disease, poor prognosis, and reduced overall survival. Tumor STn expression is well established and can be leveraged for targeted cancer therapy, however its expression on immuno-suppressive tumor infiltrating lymphocytes such as MDSCs has not been established. Methods: We generated humanized anti-STn mAbs having no cross-reactivity to the asialylated form of STn (Tn) or other glycan antigens. The epitope targeted by these mAbs is the STn glycan itself, not a particular glycopeptide or carrier protein, which offers the broadest potential to bind to multiple STn-glycosylated proteins on cell surfaces. We used these mAbs to quantify specifically the expression of tumor and MDSC STn expression across a set of patient tumor samples. We further treated mice with a humanized anti-STn-MMAE antibody-drug conjugate to evaluate targeted depletion of STn+ MDSCs. In order to evaluate the therapeutic potential of targeting this MDSC phenotype, we further evaluated the immunosuppressive environment of tumors containing STn+ and STn- MDSCs. Results: For the first time, we report the detection of STn on the surface of MDSCs in a growing body of patient tumor samples. Our data in patients as well as xenograft models additionally links STn expression on MDSCs to tumor cell STn expression. We have also demonstrated depletion of STn+ MDSCs after treatment with an anti-STn antibody-drug conjugate in an ovarian carcinoma xenograft model. Conclusions: Our data demonstrated that STn provides a uniquely glycan-specific and potent target for treatment of solid tumors. Anti-STn therapeutics offer the potential to go beyond tumor targeting to also directly target and deplete immune-suppressive MDSCs, thus fostering immune re-engagement and increasing the potential for better patient outcomes.

Citation Format: David A. Eavarone, Patricia E. Rao, Jillian M. Prendergast, Adam D. Curtis, Rong Zhang, Lindsay S. Shopland, Jenna N. Stein, Jeff Behrens, Daniel T. Dransfield. Myeloid derived suppressor cells (MDSCs) express Sialyl Tn (STn) and are a therapeutic target for anti-STn antibody drug conjugates [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5625.

Treatment of ovarian cancer by targeting the tumor stem cell-associated carbohydrate antigen, Sialyl-Thomsen-nouveau

Recurrent ovarian cancer (OvCa) is thought to result in part from the inability to eliminate rare quiescent cancer stem cells (CSCs) that survive cytotoxic chemotherapy and drive tumor resurgence. The Sialyl-Thomsen-nouveau antigen (STn) is a carbohydrate moiety present on protein markers of CSCs in pancreatic, colon, and gastric malignancies. We have demonstrated that human OvCa cell lines contain varying levels of cells that independently express either STn or the ovarian CSC marker CD133. Here we determine co-expression of STn and CD133 in a subset of human OvCa cell lines. Analyses of colony and sphere forming capacity and of response to standard-of-care cytotoxic therapy suggest a subset of OvCa STn+ cells display some CSC features. The effect of the anti-STn antibody-drug conjugates (ADCs) S3F-CL-MMAE and 2G12-2B2-CL-MMAE on OvCa cell viability in vitro and in vivo was also assessed. Treatment with S3F-CL-MMAE reduced the viability of two of three OvCa cell lines in vitro and exposure to either S3F-CL-MMAE or 2G12-2B2-CL-MMAE reduced OVCAR3-derived xenograft volume in vivo, depleting STn+ tumor cells. In summary, STn+ cells demonstrate some stem-like properties and specific therapeutic targeting of STn in ovarian tumors may be an effective clinical strategy to eliminate both STn+ CSC and STn+ non-CSC populations.

Abstract B114: Humanized anti-Sialyl-Tn monoclonal antibody-drug conjugates inhibit tumor growth in vitro and in vivo

Targeted therapeutics that can differentiate between normal and malignant tumor cells represent the ideal standard for the development of a successful anticancer strategy. The Sialyl-Thomsen-nouveau antigen (STn or Sialyl-Tn, also known as CD175s) is rarely observed in normal adult tissues, but it is abundantly expressed in many types of human epithelial cancers. Interestingly, we have observed that the level of this carbohydrate is elevated following chemotherapy treatment in both in vitro and in vivo model systems, suggesting a potential role of STn in chemoresistance. We have identified and humanized a panel of mouse monoclonal novel antibodies (Abs) that specifically target with high affinity the STn glycan independent of its carrier protein. We have demonstrated that these Abs are highly selective in binding assays demonstrating robust nanomolar EC50s, possess specificity on cancer tissues as determined with neuraminidase treatment, and exhibit STn-specific glycan binding on Siamab’s proprietary glycan array. Antitumor efficacy was evaluated in vitro and in vivo utilizing humanized anti-STn antibody-drug conjugated (ADC) material using MMAE as the cytotoxic agent. Cell cytotoxicity was demonstrated in a panel of STn-expressing cell lines with low nanomolar IC50s. In vivo, single-dose mouse PK studies were performed with humanized anti-STn ADCs and we determined half-life of approximately 3 days for both SIA01-ADC and SIA02-ADC. We confirmed that the decrease in proliferation in vitro can be translated to a reduction in tumor size in vivo through a series of cell line-derived and patient-derived (PDX) ovarian cancer and pancreatic cancer xenograft models. Inhibition of tumor progression was observed in all models with complete regressions observed in some treatment arms. No significant weight loss occurred in any treatment groups, indicating the therapy was well tolerated by all the groups. A decrease in STn expression was noted in the tumors following treatment, indicating that we were hitting the target against which these Abs were generated. In addition to these preclinical pharmacology studies, we demonstrated that the administration of our anti-STn ADC has an excellent safety profile through the completion of a non-GLP pilot PK/toxicity study in cynomolgus monkeys. No weight loss or deaths occurred in this study and no gross pathology changes were observed in all organs examined. Histopathologic changes were limited to the bone marrow with minimal to mild decreased cellularity and mild decrease in the myeloid to erythroid ratio observed. All clinical chemistry results (liver, kidney function, etc.) were normal throughout study. Changes in hematology parameters–modest neutropenia–were consistent with other MMAE ADCs and therefore, we conclude, are not related to the STn target, which is consistent with our tissue cross-reactivity studies demonstrating that overall normal tissue expression of the STn target is insignificant. Our data demonstrate that high-affinity, STn-selective humanized mAbs show promise as therapies for solid tumors.

Citation Format: Daniel Dransfield, Jillian M. Prendergast, David A. Eavarone, Rawan Nazer, Linah Al-Alem, Bo Rueda, Jenna Stein, Jeff Behrens. Humanized anti-Sialyl-Tn monoclonal antibody-drug conjugates inhibit tumor growth in vitro and in vivo [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr B114.

Abstract 36: Novel anti-Sialyl-Tn monoclonal antibodies and antibody-drug conjugates (ADCs) demonstrate tumor specificity in vitro and in vivo antitumor efficacy

Tumor-associated carbohydrate antigens (TACAs) historically have been challenging targets for antibody therapeutics. Sialyl-Tn (STn) is a cancer specific antigen that is expressed on the cell surface of carcinomas including ovarian, colon, prostate, and pancreatic tumors but is rarely present in normal tissue. STn expression has been linked to innate immune suppression, a chemoresistant phenotype, metastasis, and poor prognosis. Previous attempts to target this antigen in the clinic with synthetic glycan vaccines proved safe but lacked efficacy. We have developed highly selective humanized monoclonal antibodies and antibody drug conjugates (ADCs) targeting TACAs, such as STn. Remarkable sequence homology across all anti-STn mAbs was observed in both heavy and light chains, and hot spots for hypermutation were identified. These antibodies were selected using our glycan microarray that enriches for candidates whose binding is protein-independent, highly selective and demonstrates exceptional target affinity.

Lead humanized candidates demonstrated single digit nanomolar EC50s in ELISA/flow cytometric assays, STn selective cell internalization, and STn specific glycan binding on Siamab’s proprietary glycan array. STn binding sites in common tumor lines (ovarian, gastric and breast) were determined per cell and subsequent cytotoxicity assays in these lines demonstrated in vitro efficacy. Tumor microarray experiments revealed membranous staining in cancerous tissues of various indications. Binding studies of anti-STn antibodies to primary human cancer samples by flow cytometry demonstrated that both tumor and Myeloid-Derived Suppressor Cells (MDSC, both myeloid and granulocytic) express STn. In an OVCAR3 xenograft model, 30 days after the last anti-STn ADC dose was given, groups treated (Q7Dx4) exhibited mean tumor volumes below the Day 1 pre-treatment mean tumor volumes (155mm3). Flow cytometric analysis of tumors from these mice demonstrated that anti-STn ADC treatment reduces STn expression on the primary tumor in a dose-dependent manner (Q7Dx4 vs. single dose) compared to the isotype-ADC control. Our data demonstrates that high-affinity, STn-selective mAbs show promise as therapies for solid tumors and could also target MDSCs to promote antitumor immune responses.

Citation Format: Jillian M. Prendergast, David A. Eavarone, Patricia E. Rao, Adam D. Curtis, Lindsay S. Shopland, Todd A. Hoffert, Jenna Stein, Jeff Behrens, Daniel T. Dransfield. Novel anti-Sialyl-Tn monoclonal antibodies and antibody-drug conjugates (ADCs) demonstrate tumor specificity in vitro and in vivo antitumor efficacy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 36. doi:10.1158/1538-7445.AM2017-36

Novel anti-Sialyl-Tn monoclonal antibodies and antibody-drug conjugates demonstrate tumor specificity and anti-tumor activity

Targeted therapeutics that can differentiate between normal and malignant tumor cells represent the ideal standard for the development of a successful anti-cancer strategy. The Sialyl-Thomsen-nouveau antigen (STn or Sialyl-Tn, also known as CD175s) is rarely seen in normal adult tissues, but it is abundantly expressed in many types of human epithelial cancers. We have identified novel antibodies that specifically target with high affinity the STn glycan independent of its carrier protein, affording the potential to recognize a wider array of cancer-specific sialylated proteins. A panel of murine monoclonal anti-STn therapeutic antibodies were generated and their binding specificity and efficacy were characterized in vitro and in in vivo murine cancer models. A subset of these antibodies were conjugated to monomethyl auristatin E (MMAE) to generate antibody-drug conjugates (ADCs). These ADCs demonstrated in vitro efficacy in STn-expressing cell lines and significant tumor growth inhibition in STn-expressing tumor xenograft cancer models with no evidence of overt toxicity.

Social Network Relationships and Use of Physician Services

The typology of social network relationships proposed by Rundall and Evashwick (1982) is reexamined in light of data from a survey of a random sample of noninstitutionalized elderly. The original four types of relationships (engaged, disengaged, trapped, and abandoned) are extended to include "discontented' and "alienated" relationships. Hypotheses derived from the typology are tested with data on use of physician services. The most common types of relationships found in this sample are the engaged, disengaged, and abandoned. Of these, the abandoned have the highest average number of physician visits. Promising avenues of further investigation are noted.

A randomized trial of exercise programs among older individuals living in two long-term care facilities: the FallsFREE program

OBJECTIVE

To use two different exercise programs over a 2-year period to reduce falls and their sequelae among residents of two long-term care facilities.

DESIGN

Randomized, controlled trial.

SETTING

The study took place at two long-term care facilities with services ranging from independent living to skilled nursing.

PARTICIPANTS

One hundred and ten participants whose average age was 84 and who were capable of ambulating with or without assistive devices and could follow simple directions.

INTERVENTION

Participants were randomized to one of two exercise groups (resistance/endurance plus basic enhanced programming or tai chi plus basic enhanced programming) or to a control group (basic enhanced programming only). Exercise classes were held three times per week throughout the study.

MEASUREMENTS

Participants were evaluated for cognitive and physical functioning at baseline and 6, 12, and 24 months. Falls were determined from incident reports filed by the nursing staffs at the facilities.

RESULTS

Time to first fall, time to death, number of days hospitalized, and incidence of falls did not differ among the treatment and control groups (P>.05). Among all participants, those who fell had significantly lower baseline Folstein Mini-Mental State Examination and instrumental activities of daily living scores and experienced significantly greater declines in these measures over the 2-year program.

CONCLUSION

There were no significant differences in falls among the two exercise groups and the control group. Lack of treatment differences and low adherence rates suggest that residents of long-term care facilities may require individualized exercise interventions that can be adapted to their changing needs.

A low-level strength training exercise program for frail elderly adults living in an extended attention facility

Little is known about low-level, mildly progressive, strength training programs for frail elderly adults who live in extended attention housing. To study the effects of a low-level strength training program, a group of 12 frail elderly adults, aged 70 to 93 years, residing in an extended attention facility, participated in a strength training exercise program using ankle and wrist weights. Baseline measurements of elbow and knee flexor and extensor muscle strength were taken with a handheld dynamometer prior to initiation of the strength training program, and every three weeks during the 12-week period of exercise with weights. Muscle strength of elbow and knee flexors improved significantly by the end of the 12-week period (p < 0.05). Elbow and knee extensors did not show significant increases in muscle strength, but were maintained. It is concluded that muscle strength can be maintained or improved in adults over 70 who live in an extended attention facility using a low-level, mildly progressive, resistive exercise program. The program is safe, inexpensive, practical and can be used in clinical as well as community settings.

Progress in the development of a nutritional risk index

The development of a 16-item nutritional risk index (NRI) is chronicled from its inception through its application in three studies designed to assess its reliability and validity. Study I involved a survey of 401 community-dwelling elderly in St. Louis, Missouri who were interviewed at baseline, 4-5 mo later, and 1 yr later. Study II involved a cross-sectional survey of 377 male outpatients attending two clinics at the St. Louis Veterans Administration Medical Center. Study III involved a cross-sectional survey of 424 community-dwelling elderly in Houston, Texas. Internal consistency reliability coefficients ranged between 0.47 and 0.60, and test-retest reliability coefficients ranged between 0.65 and 0.71. Validity was established by using the NRI to predict the use of health services, as well as by correlating it with a variety of anthropometric, laboratory, and clinical markers of nutritional status. The utility of the NRI for future applications is discussed.

Clinical validation of a nutritional risk index

This research assessed the clinical validity of a nutritional risk index (NRI). Subjects were 377 male veterans, aged 55+, attending general medicine and geriatric outpatient clinics. Data were collected by personal interviews, anthropometric measurements, laboratory assay of nutritional parameters, three-day food records, and medical record reviews. Although the results showed that the NRI correlated significantly with only two nutritional measures (body mass index, total energy intake), critical values or threshold levels of NRI were identified that significantly discriminated low risk from high risk patients on four nutritional parameters (body mass index, total energy intake, laboratory risk, and medications risk). It was concluded that the NRI is a valid measure of health status and contains a nutritional dimension.

Further assessment of the reliability and validity of a Nutritional Risk Index: analysis of a three-wave panel study of elderly adults

This paper reports on the further assessment of the reliability and validity of a short (16-item), portable method for assessing nutritional risk which is easily administered in the typical social survey setting. Data were obtained from a three-wave panel study of 401 randomly selected, noninstitutionalized elderly persons (age 65 and over) in St. Louis. Reliability was assessed by both internal consistency and test-retest methods. Reliability coefficients (internal consistency) of .603, .544, and .515 were obtained at T-1, T-2, and T-3, respectively. Cross-panel intercorrelations (test-retest) ranged between .67 and .71. Validity was assessed using factor analysis and various outcome measure comparisons for those at risk versus those not at risk. A five-factor orthogonally rotated solution explained 47.9 percent of the variance in the 16 items. Individuals with higher risk scores had significantly poorer health as measured by other standard indexes, and used significantly more health services than those with lower risk scores. These results underscore the potential of the Nutritional Risk Index (NRI) as a screening device for use among the elderly.

Immunologic modulation by vitamin C in the elderly

Aging is associated with a decline in both humoral-mediated and cellular-mediated immunity. These aberrations may contribute to morbidity and mortality in the elderly. Since we have previously shown that vitamin C enhances in vitro and in vivo immune functions in young healthy volunteers, we studied the effects of vitamin C on certain immunologic parameters in an elderly population. In vitro lymphocyte proliferation to the mitogen concanavalin-A was significantly less when compared to a young control group. When lymphocytes from the elderly were pre-incubated overnight and cultured in the presence of 10 micrograms/ml of vitamin C, mitogen-stimulated lymphocyte proliferation was similar to that from controls without vitamin C in culture. Having demonstrated significant in vitro immunoenhancement with vitamin C, we next studied the effects of oral ingestion of 2 g of vitamin C daily on certain in vitro and in vivo immunologic parameters in the elderly. When compared with a placebo-treated group, 3 weeks of vitamin C treatment did not effect in vitro mitogen-stimulated lymphocyte proliferation or in vivo reactivity to common skin test antigens. The augmenting effects of in vitro vitamin C suggest that this essential vitamin may be an effective agent in modulating aberrant immunologic functions in the elderly. The clinical significance of these findings requires further study.

Elderly persons without family support networks and use of health services. A follow-up report on social network relationships

This article compares the use of health services by a random sample of 394 noninstitutionalized elderly. Elderly persons without family used hospital emergency rooms (ER) 7 to 30 times more often than elderly persons with family in the area. Differences among them for physicians' visits or hospital utilization, however, were not statistically significant. Because elderly without family in the area had similar health status as elderly with family, absence of family access to a lay referral system is thought to be the principal reason for increased use of ER services, especially for nonurgent care.

Correlates of change in subjective well-being among the elderly

This study examines two related issues concerning the subjective well-being of elderly adults: change over time and correlates of that change. Data come from a three-wave panel study of 401 elderly residents in St. Louis. Residualized change score regression analyses indicate: there is change in subjective well-being over 4-5 months and over 12 months; the 4-5 month and 12 month changes are remarkably similar; the effect of subjective well-being over time indicates regression to the mean; and, only socioeconomic status is a significant predictor of change in subjective well-being (net of the effects of subjective well-being itself). The implications of these results for our understanding of subjective well-being in the elderly are discussed, as are the policy implications of the positive effect of socioeconomic status on changes in the subjective well-being of the elderly.

A preliminary validation of a nutritional risk measure for the elderly

We used data from a two-stage random sample of 401 noninstitutionalized elderly individuals residing in 18 census tracts in south-central metropolitan St. Louis to establish the reliability and validity of a 16-item nutritional risk measure. Reliability analysis yielded a Cronbach's alpha of 0.603. Concurrent predictive validity was demonstrated by the prediction of physician, emergency room, and hospital use. Individuals with high scores displayed a consistent pattern of higher rates of known nutrition-related problems and their sequelae than did those with low scores, providing evidence of known groups validity. Statistical correlations with components of an established theoretical model of the elderly's health and illness behavior demonstrate preliminary support for construct validity. The advantages of our nutritional risk measure include its ease of administration and telephone portability.

Measurement of the global and functional dimensions of health status in the elderly

Data from a two-stage random sample of 401 noninstitutionalized elderly individuals residing in 18 census tracts in south-central metropolitan St. Louis were used to examine the relationships among seven measures of health status. Factor analyses revealed two pristine dimensions: (a) a global health status dimension, on which perceived health status, nutritional risk, perceived sensory functions, and mental health all load significantly; and, (b) a functional dimension on which the Activities of Daily Living, Instrumental Activities of Daily Living, and mental orientation measures all load significantly. These two factors explain 56% of the variance in the seven health status measures, and, using an oblique rotational procedure, they were found to be correlated only modestly (r = .37). The implications for the measurement of health status of elderly adults as well as the use of such measures in predicting health services utilization are discussed, and recommendations for the inclusion of items tapping both dimensions in future studies are presented.

Attitudes and health promoting behavior of medical and law students

An entering class of medical students is compared with an entering class of law students on attitudes toward self-responsibility for health and reported health behaviors. Students' health behavior patterns are contrasted with those of practicing physicians and lawyers. Data were collected by self-administered questionnaires. Results indicated that medical students were stronger on self-responsibility and also reported more often engaging in health promoting behavior than law students. The same pattern of differences was reported for practicing physicians and lawyers.

Faculty resources for teaching geriatric medicine

Self-administered questionnaires were sent to all faculty and staff members of the departments of internal medicine and psychiatry in a school of medicine. The questionnaires asked for information about personal characteristics, practice characteristics, and interest in teaching geriatrics. Included also were measures of knowledge about aging and attitudes toward the elderly. Responses were received from 25 per cent of the faculty. Results indicated that 40 per cent wanted no involvement in teaching geriatrics. Of the remainder, most preferred a consultant's role on a clinical service. Despite extensive experience with elderly patients, respondents showed modest scores on knowledge, but there was little stereotyping of elderly patients. Implications for establishing a training program in geriatrics are discussed.