Stem/progenitor cells play central roles in processes of organogenesis and tissue maintenance, whereas cancer stem cells (CSCs) are thought to drive tumor malignancy. Here, we review recent progress in the identification and analysis of normal prostate stem/progenitor cells as well as putative CSCs in both genetically engineered mouse models as well as in human tissue. We also discuss studies that have investigated the cell type of origin for prostate cancer. In addition, we provide a critical assessment of methodologies used in stem cell analyses and outline directions for future research.

BACKGROUND: Patient-derived tumor organoid culture has emerged as a preclinical model that has the potential to predict individual drug response. However, the predictive accuracy of patient-derived tumor organoid culture models for responses to chemotherapy regimens in stage IV colorectal cancer remains unknown. OBJECTIVE: The purpose of this study was to evaluate the predictive accuracy of the patient-derived tumor organoid culture model for responses to chemotherapy regimens in stage IV colorectal cancer. DESIGN: A pilot study was performed to define the half-maximal inhibitory concentration of the response to chemotherapy regimens in the patient-derived tumor organoid culture model. Then, a blinded study was performed to evaluate the predictive accuracy of the patient-derived tumor organoid culture model for responses to chemotherapy regimens. SETTINGS: Cancer samples were collected from patients with stage IV colorectal cancer at Nanfang Hospital of Southern Medical University in China. PATIENTS: In the pilot study, 30 patients were enrolled, and 43 samples were collected. In the blinded study, 71 patients were enrolled, and 96 samples were collected. INTERVENTION: Patient-derived tumor organoid culture and chemotherapy regimens were tested. MAIN OUTCOME MEASURES: The predictive accuracy of the patient-derived tumor organoid model for responses to chemotherapy regimens was measured. RESULTS: The median (range) time of organoid culture and drug testing was 9 days (range, 7–14 d). In the pilot study, 30 samples (69.77% [30/43]) were successfully cultured. The half-maximal inhibitory concentration of the chemotherapy response was 10 µmol/L according to clinical chemotherapy outcomes. In the blinded study, 77 samples (80.21% [77/96]) from 57 patients were successfully cultured. The sensitivity, specificity, and accuracy of the patient-derived tumor organoid model for predicting responses to chemotherapy regimens were 63.33%, 94.12%, and 79.69%. LIMITATIONS: This was a blinded study rather than a prospective randomized controlled study. CONCLUSIONS: The patient-derived tumor organoid culture model effectively predicts responses to existing chemotherapy regimens for individual patients. Video Abstract at http://links.lww.com/DCR/B511. PRECISIÓN EN EL USO DE MODELOS DE CULTIVO DE ORGANOIDES TUMORALES DERIVADOS DE PACIENTES PARA PREDECIR LA RESPUESTA DEL RÉGIMEN DE QUIMIOTERAPIA EN CÁNCER COLORRECTAL ESTADIO IV: ESTUDIO CIEGO ANTECEDENTES: El cultivo de organoides tumorales derivado del paciente ha surgido como un modelo preclínico que tiene el potencial de predecir la respuesta a un fármaco individual. Sin embargo, la exactitud predictiva en los modelos de cultivo de organoides tumorales derivados de pacientes para las respuestas a los regímenes de quimioterapia en el cáncer colorrectal en estadio IV sigue siendo desconocida. OBJETIVO: Evaluar la exactitud predictiva del modelo de cultivo organoide tumoral derivado de pacientes para las respuestas a los regímenes de quimioterapia en el cáncer colorrectal en estadio IV. DISEÑO: Se realizó un estudio piloto para definir la concentración inhibitoria media máxima de la respuesta a los regímenes de quimioterapia en el modelo de cultivo organoide tumoral derivado de pacientes. Luego, se realizó un estudio ciego para evaluar la exactitud predictiva del modelo de cultivo organoide tumoral derivado de pacientes para las respuestas a los regímenes de quimioterapia. AJUSTE: Se recolectaron muestras de cáncer de pacientes con cáncer colorrectal en estadio IV en el Hospital Nanfang de la Universidad Médica del Sur en China. PACIENTES: En el estudio piloto, se inscribieron 30 pacientes y se recolectaron 43 muestras. En el estudio ciego, se inscribieron 71 pacientes y se recolectaron 96 muestras. INTERVENCIÓN: Se probaron cultivos de organoides de tumores derivados del paciente y regímenes de quimioterapia. PRINCIPALES MEDIDAS DE RESULTADO: La precisión predictiva del modelo organoide tumoral derivado del paciente para las respuestas a los regímenes de quimioterapia. RESULTADOS: La mediana (rango) de tiempo de cultivo organoide y prueba de drogas fue de 9 (7-14) días. En el estudio piloto, se cultivaron con éxito 30 (69,77% [30/43]) muestras. La concentración inhibidora media máxima de la respuesta a la quimioterapia fue de 10 µmol / L según los resultados de la quimioterapia clínica. En el estudio ciego, se cultivaron con éxito 77 muestras (80,21% [77/96]) de 57 pacientes. La sensibilidad, especificidad y precisión del modelo organoide tumoral derivado del paciente para predecir las respuestas a los regímenes de quimioterapia fueron 63,33%, 94,12% y 79,69%, respectivamente. LIMITACIONES: Este fue un estudio ciego en lugar de un estudio prospectivo, aleatorizado y controlado. CONCLUSIONES: El modelo de cultivo organoide tumoral derivado de pacientes predice eficazmente las respuestas a los regímenes de quimioterapia existentes para pacientes individuales. Consulte Video Resumen en http://links.lww.com/DCR/B511.

causes an array of serious infections resulting in high morbidity and mortality worldwide. This study evaluated naturally occurring serum anti-alpha-toxin (anti-AT) antibody levels in human subjects from various age groups, individuals with dialysis and surgical-site infections, and-colonized versus noncolonized subjects. Anti-AT immunoglobulin G (IgG) and neutralizing antibody (NAb) levels in infants (aged ≤1 year) were significantly lower than those in other populations. In comparison to adolescent, adult, and elderly populations, young children (aged 2 to 10 years) had equivalent anti-AT IgG levels but significantly lower anti-AT NAb levels. Therefore, the development of anti-AT NAbs appears to occur later than that of AT-specific IgG, suggesting a maturation of the immune response to AT. Anti-AT IgG levels were slightly higher in -colonized subjects than in noncolonized subjects. The methicillin susceptibility status of colonizing isolates had no effect on anti-AT antibody levels in-colonized subjects. The highest anti-AT IgG and NAb levels were observed in dialysis patients with acute infection. Anti-AT IgG and NAb levels were well correlated in subjects aged>10 years, regardless of colonization or infection status. These data demonstrate that AT elicits a robust IgG humoral response in infants and young children that becomes stable prior to adolescence, matures into higher levels of NAbs in healthy adolescents, and becomes elevated during infection. These findings may assist in identifying subjects and patient populations that could benefit from vaccination or immunoprophylaxis with anti-AT monoclonal antibodies.

Abstract. Benralizumab is a humanized anti-IL5 receptor α (IL5Rα) monoclonal antibody (mAb) with enhanced (afucosylation) antibody-dependent cell-mediated cytotoxicity (ADCC) function. An ADCC reporter cell-based neutralizing antibody (NAb) assay was developed and characterized to detect NAb against benralizumab in human serum to support the clinical development of benralizumab. The optimal ratio of target cells to effector cells was 3:1. Neither parental benralizumab (fucosylated) nor benralizumab Fab resulted in ADCC activity, confirming the requirement for ADCC activity in the NAb assay. The serum tolerance of the cells was determined to be 2.5%. The cut point derived from normal and asthma serum samples was comparable. The effective range of benralizumab was determined, and 35 ng/mL [80% maximal effective concentration (EC 80 )] was chosen as the standard concentration to run in the assessment of NAb. An affinity purified goat anti-benralizumab polyclonal idiotype antibody preparation was shown to have NAb since it inhibited ADCC activity in a dosedependent fashion. The low endogenous concentrations of IL5 and soluble IL5 receptor (sIL5R) did not demonstrate to interfere with the assay. The estimated assay sensitivities at the cut point were 1.02 and 1.10 μg/mL as determined by the surrogate neutralizing goat polyclonal and mouse monoclonal anti-drug antibody (ADA) controls, respectively. The assay can detect NAb (at 2.5 μg/mL) in the presence of 0.78 μg/mL benralizumab. The assay was not susceptible to non-specific matrix effects. This study provides an approach and feasibility of developing an ADCC cell-based NAb assay to support biopharmaceuticals with an ADCC function.

Assessment of anti-drug antibodies (ADAs) for neutralizing activity is important for the clinical development of biopharmaceuticals. Two types of neutralizing antibody (NAb) assays (competitive ligand-binding assay [CLBA] and cell-based assay [CBA]) are commonly used to characterize neutralizing activities. To support the clinical development of benralizumab, a humanized, anti-interleukin-5 receptor α, anti-eosinophil monoclonal antibody, we developed and validated a CLBA and a CBA. The CLBA and CBA were compared for sensitivity, drug tolerance, and precision to detect NAbs in serum samples from clinical trials. The CLBA was more sensitive (27.1 and 37.5 ng/mL) than the CBA (1.02 and 1.10 μg/mL) in detecting NAbs to benralizumab for the polyclonal and monoclonal ADA controls, respectively. With the same polyclonal ADA control, the CLBA detected 250 ng/mL of ADA in the presence of 100 ng/mL of benralizumab, whereas the CBA detected 1.25 μg/mL of ADA in the presence of 780 ng/mL of benralizumab. In 195 ADA-positive samples from 5 studies, 63.59% (124/195) and 16.9% (33/195) were positive for NAb as measured by the CLBA and the CBA, respectively. ADA titers were strongly correlated (Pearson's correlation coefficient r = 0.91; n = 195) with CLBA titers. Moreover, the CLBA titer correlated with CBA percentage inhibition in the CBA-positive samples (Spearman's coefficient r = 0.50; n = 33). Our data demonstrated advantages of the CLBA in various aspects and supported the choice of the CLBA as a NAb assay for the phase III trials.