Leanne Goldstein

Hyperphosphatemia is a combined function of high serum PTH and high dietary protein intake in dialysis patients

Elevated serum phosphorus is associated with higher death risk in hemodialysis patients. Previous studies have suggested that both higher serum parathyroid hormone (PTH) level and higher dietary protein intake may contribute to higher serum phosphorus levels. However, it is not well known how these two factors simultaneously contribute to the combined risk of hyperphosphatemia in real patient-care scenarios. We hypothesized that the likelihood of hyperphosphatemia increases across higher serum PTH and higher normalized protein catabolic rate (nPCR) levels, a surrogate of protein intake. Over an 8-year period (July 2001–June 2009), we identified 69,355 maintenance hemodialysis patients with PTH, nPCR, and phosphorus data in a large dialysis provider. Logistic regression models were examined to assess the association between likelihood of hyperphosphatemia (serum phosphorus >5.5 mg/dl) and serum PTH and nPCR increments. Patients were 61±15 years old and included 46% women, 33% blacks, and 57% diabetics. Both higher serum PTH level and higher protein intake were associated with higher risk of hyperphosphatemia in dialysis patients. Compared with patients with PTH level 150–<300 pg/ml and nPCR level 1.0–<1.2 g/kg/day, patients with iPTH>600 pg/ml and nPCR>1.2 g/kg/day had a threefold higher risk of hyperphosphatemia (OR: 3.17, 95% CI: 2.69–3.75). Hyperphosphatemia is associated with both higher dietary protein intake and higher serum PTH level in maintenance hemodialysis patients. Worsening or resistant hyperphosphatemia may be an under-appreciated consequence of secondary hyperparathyroidism independent of dietary phosphorus load. Management of hyperphosphatemia should include diligent correction of hyper-parathyroidism while maintaining adequate intake of high protein foods with low phosphorus content.

Culture-Sensitive Question Order Effects of Self-Rated Health Between Older Hispanic and Non-Hispanic Adults in the United States.

Objective: The aim of this study is to examine context effects created by the question order for self-rated health (SRH) by race/ethnicity and language. Method: Differences in SRH estimates for non-Hispanic Whites and Hispanics were first examined with multiple observational data that asked SRH in different contexts. To examine context effects by socio-demographics and health-related characteristics, we conducted experiments on SRH question order. Results: While Hispanics reported poorer health than non-Hispanic Whites, this difference, in part, depended on question contexts. With SRH asked after rather than before specific health questions, Hispanics, especially Spanish-speaking Hispanics, reported better health, while non-Hispanic Whites’ reports remained consistent. Among Spanish-speaking Hispanics, the context effect was larger for unmarried and less educated persons and those with comorbidities. Discussion: Question contexts influence SRH reports by Spanish-speaking older adults. Cross-cultural inquiries on the meaning of health and its dynamics with question contexts may explain what SRH measures for increasingly diverse populations.

Patterns and Trends in Immediate Postmastectomy Reconstruction in California: Complications and Unscheduled Readmissions.

Background: Immediate reconstruction rates after mastectomy are increasing but remain low. Little is known about hospital readmissions after these procedures. The authors studied unscheduled readmissions after immediate reconstruction. Methods: Using the Healthcare Cost and Utilization Project California State database, the authors identified patients undergoing mastectomy only or with immediate reconstruction for ductal carcinoma in situ and invasive breast cancer from 2005 to 2009. Immediate reconstruction included tissue expander/implant and autologous tissue reconstructions. The authors evaluated temporal trends in immediate reconstruction and factors associated with 30-day unscheduled readmissions after reconstruction. Results: The cohort contained 48,414 patients (mastectomy only, 35,648; immediate reconstruction, 12,766; tissue expander/implant, 10,437; autologous tissue, 2329). Readmission rates were not significantly different between mastectomy only and immediate reconstruction (3.55 percent versus 3.39 percent; p = 0.39); however, autologous tissue reconstruction was associated with a significantly higher readmission rate compared with tissue expander/implant reconstruction (4.08 percent versus 3.24 percent; p = 0.04). Conclusions: Immediate reconstruction does not result in higher readmission rates compared with mastectomy only. All women undergoing mastectomy should be offered consultation for reconstruction. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, III.

Human Neural Stem Cell Biodistribution and Predicted Tumor Coverage by a Diffusible Therapeutic in a Mouse Glioma Model

Engineered neural stem cells (NSCs) intrinsically migrating to brain tumors offer a promising mechanism for local therapeutic delivery. However, difficulties in quantitative assessments of NSC migration and in estimates of tumor coverage by diffusible therapeutics have impeded development and refinement of NSC‐based therapies. To address this need, we developed techniques by which conventional serial‐sectioned formalin‐fixed paraffin‐embedded (FFPE) brains can be analyzed in their entirety across multiple test animals. We considered a conventional human glioblastoma model: U251 glioma cells orthotopically engrafted in immunodeficient mice receiving intracerebral (i.c.) or intravenous (i.v.) administrations of NSCs expressing a diffusible enzyme to locally catalyze chemotherapeutic formation. NSC migration to tumor sites was dose‐dependent, reaching 50%–60% of total administered NSCs for the i.c route and 1.5% for the i.v. route. Curiously, the most efficient NSC homing was seen with smaller NSC doses, implying existence of rate‐limiting process active during administration and/or migration. Predicted tumor exposure to a diffusing therapeutic (assuming a 50 µm radius of action) could reach greater than 50% of the entire tumor volume for i.c. and 25% for i.v. administration. Within individual sections, coverage of tumor area could be as high as 100% for i.c. and 70% for i.v. routes. Greater estimated therapeutic coverage was observed for larger tumors and for larger tumor regions in individual sections. Overall, we have demonstrated a framework within which investigators may rationally evaluate NSC migration to, and integration into, brain tumors, and therefore enhance understanding of mechanisms that both promote and limit this therapeutic modality. Stem Cells Translational Medicine 2017;6:1522–1532

Optimization of a Neural Stem-Cell-Mediated Carboxylesterase/Irinotecan Gene Therapy for Metastatic Neuroblastoma

Despite improved survival for children with newly diagnosed neuroblastoma (NB), recurrent disease is a significant problem, with treatment options limited by anti-tumor efficacy, patient drug tolerance, and cumulative toxicity. We previously demonstrated that neural stem cells (NSCs) expressing a modified rabbit carboxylesterase (rCE) can distribute to metastatic NB tumor foci in multiple organs in mice and convert the prodrug irinotecan (CPT-11) to the 1,000-fold more toxic topoisomerase-1 inhibitor SN-38, resulting in significant therapeutic efficacy. We sought to extend these studies by using a clinically relevant NSC line expressing a modified human CE (hCE1m6-NSCs) to establish proof of concept and identify an intravenous dose and treatment schedule that gave maximal efficacy. Human-derived NB cell lines were significantly more sensitive to treatment with hCE1m6-NSCs and irinotecan as compared with drug alone. This was supported by pharmacokinetic studies in subcutaneous NB mouse models demonstrating tumor-specific conversion of irinotecan to SN-38. Furthermore, NB-bearing mice that received repeat treatment with intravenous hCE1m6-NSCs and irinotecan showed significantly lower tumor burden (1.4-fold, p = 0.0093) and increased long-term survival compared with mice treated with drug alone. These studies support the continued development of NSC-mediated gene therapy for improved clinical outcome in NB patients.

Evaluation of innate and adaptive immunity contributing to the antitumor effects of PD1 blockade in an orthotopic murine model of pancreatic cancer.

ABSTRACT Despite the clinical success of anti-PD1 antibody (α-PD1) therapy, the immune mechanisms contributing to the antineoplastic response remain unclear. Here, we describe novel aspects of the immune response involved in α-PD1-induced antitumor effects using an orthotopic KrasG12D/p53R172H/Pdx1-Cre (KPC) model of pancreatic ductal adenocarcinoma (PDA). We found that positive therapeutic outcome involved both the innate and adaptive arms of the immune system. Adoptive transfer of total splenocytes after short-term (3 d) but not long-term (28 d) PD1 blockade significantly extended survival of non-treated tumor-bearing recipient mice. This protective effect appeared to be mostly mediated by T cells, as adoptive transfer of purified natural killer (NK) cells and/or granulocyte receptor 1 (Gr1)+ cells or splenocytes depleted of Gr1+ cells and NK cells did not exhibit transferrable antitumor activity following short-term PD1 blockade. Nevertheless, splenic and tumor-derived CD11b+Gr1+ cells and NK cells showed significant persistence of α-PD1 bound to these cells in the treated primary recipient mice. We observed that short-term inhibition of PD1 signaling modulated the profiles of multifunctional cytokines in the tumor immune-infiltrate, including downregulation of vascular endothelial growth factor A (VEGF-A). Altogether, the data suggest that systemic blockade of PD1 results in rapid modulation of antitumor immunity that differs in the tumor microenvironment (TME) when compared to the spleen. These results demonstrate a key role for early immune-mediated events in controlling tumor progression in response to α-PD1 treatment and warrant further investigation into the mechanisms governing responses to the therapy at the innate-adaptive immune interface.

Modeling longitudinal data and its impact on survival in observational nephrology studies: tools and considerations

Abstract Nephrologists and kidney disease researchers are often interested in monitoring how patients’ clinical and laboratory measures change over time, what factors may impact these changes, and how these changes may lead to differences in morbidity, mortality, and other outcomes. When longitudinal data with repeated measures over time in the same patients are available, there are a number of analytical approaches that could be employed to describe the trends and changes in these measures, and to explore the associations of these changes with outcomes. Researchers may choose a streamlined and simplified analytic approach to examine trajectories with subsequent outcomes such as estimating deltas (subtraction of the last observation from the first observation) or estimating per patient slopes with linear regression. Conversely, they could more fully address the data complexity by using a longitudinal mixed model to estimate change as a predictor or employ a joint model, which can simultaneously model the longitudinal effect and its impact on an outcome such as survival. In this review, we aim to assist nephrologists and clinical researchers by reviewing these approaches in modeling the association of longitudinal change in a marker with outcomes, while appropriately considering the data complexity. Namely, we will discuss the use of simplified approaches for creating predictor variables representing change in measurements including deltas and patient slopes, as well more sophisticated longitudinal models including joint models, which can be used in addition to simplified models based on the indications and objectives of the study as warranted.

Abstract B170: Blockade of checkpoint programmed death 1 (PD1) delays tumor growth and induces early transferable protective immunity in a murine orthotopic pancreatic ductal adenocarcinoma model

Despite the growing understanding of how PD1 signaling contributes to the immunosuppressed tumor microenvironment (TME), the mechanisms underlying tumor regression by antibody blockade remain unclear. In this study, we sought to identify the early events involved in mediating the anti-tumor effects of anti-PD1 monoclonal antibody (α-PD1 mAb) using an orthotopic mutant KrasG12D/p53R172H Pdx-Cre (KPC) pancreatic ductal adenocarcinoma (PDA) model. This model is clinically relevant because in addition to KPC cells constitutively expressing the programmed death 1 ligand 1 (PD-L1), it represents advanced tumors due to its fast growth and drug resistant phenotype. When compared to hamster IgG isotype, single dose treatment with α-PD1 mAb (clone J43, 250µg/mouse) prolonged survival in C57BL6 mice bearing well established tumors (32 vs 76 days median survival time, respectively, p=0.0003). Mice that received α-PD1 mAb therapy presented transient moderate splenomegaly with increased spleen cellularity 72 hours following mAb administration. To determine if the transient splenomegaly represented a correlate of immune protection against tumor challenge, splenocytes from tumor bearing mice treated with IgG isotype or α-PD1 mAb for 72 hours, 7 days or 4 weeks were transferred into recipient tumor bearing mice that were pre-conditioned with cyclophosphamide (100mg/kg). Surprisingly, transferable protective immunity was only observed in the group that received splenocytes from donor mice treated with α-PD1 mAb for 72 hours (39.5 vs. 63 days median survival time for the IgG isotype vs. α-PD1 mAb treated group, p=0.042). Analysis by real time qPCR of tumor-infiltrating lymphocytes (TIL) obtained by selection of CD45+ cells using magnetic beads showed an increase in mRNA expression of IL-6 (4.6 fold), IL-8 (2.7 fold), IL-10 (6.2 fold), IFN-γ (3.8 fold) and TNF-α (4 fold) at 7 days, but not at 72 hours after PD1 blockade, suggesting that alterations in the splenic microenvironment influenced subsequent immune activation in the TME. Furthermore, individual depletion of immune cell subsets generally regarded as involved with the innate (Gr1+ cells, NK cells) or adaptive arms of the immune response (CD4 or CD8 T cells) were all capable of blocking the effect of α-PD1 mAb therapy in donor mice (p≤0.001). These results corroborate the importance of tumor recognition by the innate immune system in order to activate T cell-mediated killing, showing that stimulation of innate and/or adaptive immunity may play a direct role in controlling tumor progression. Alternatively, gene expression analysis using the non-TIL enriched fraction (remaining CD45- cells) extracted from tumors 7 days after PD1 inhibition showed downregulation of vascular endothelial growth factor A (VEGF-A) and G1/S related cyclin mRNA, such as cyclin-A, -D2 and E, suggesting that inhibition of PD1 induced tumor cell cycle arrest occurred concomitantly with upregulation of cytokine expression. Downregulation of VEGF-A was confirmed by ELISA using whole tumor extracts (p=0.03). Even though IL-10 is an inhibitor of VEGF-A, in vitro experiments using KPC cells failed to demonstrate a direct connection. However, TME conditions are complex, and often non-reproducible in vitro. Based on our results, we challenge the notion that PD1 blockade inhibits tumor progression mainly as a result of activating canonical adaptive immune responses. In addition, induction of G1/S tumor cell cycle arrest could increase sensitivity to cytotoxic therapies, thus providing a rationale for drug combinations. Given the broad role of VEGF-A in fostering an immunosuppressive TME and as an endothelial/epithelial growth factor, further studies are underway to investigate the role of VEGF-A inhibition in α-PD1 mAb-mediated tumor regression. Citation Format: Marcela d9Alincourt Salazar, Edwin Manuel, Weimin Tsai, Massimo D9Apuzzo, Leanne Goldstein, Bruce R. Blazar, Don J. Diamond. Blockade of checkpoint programmed death 1 (PD1) delays tumor growth and induces early transferable protective immunity in a murine orthotopic pancreatic ductal adenocarcinoma model. [abstract]. In: Proceedings of the CRI-CIMT-EATI-AACR Inaugural International Cancer Immunotherapy Conference: Translating Science into Survival; September 16-19, 2015; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(1 Suppl):Abstract nr B170.