A majority of breast cancers are estrogen receptor (ER) positive and have a luminal epithelial phenotype. However, these ER+ tumors often contain heterogeneous subpopulations of ER− tumor cells. We previously identified a population of cytokeratin 5 (CK5) positive cells within ER+ and progesterone receptor positive (PR+) tumors that is both ER−PR− and CD44+, a marker of breast tumor-initiating cells (TICs). These CK5+ cells have properties of TICs in luminal tumor xenografts, and we speculated that they are more resistant to chemo- and anti-ER-targeted therapies than their ER+ neighbors. To test this, we used ER+PR+ T47D and MCF7 breast cancer cells. CK5+ cells had lower proliferative indices than CK5− cells, were less sensitive to 5-fluorouracil and docetaxel, and cultures became enriched for CK5+ cells after treatments. CK5+ cells were less prone to drug-induced apoptosis than CK5− cells. In cells treated with 17β-estradiol (E) plus anti-estrogens tamoxifen or fulvestrant, ER protein levels decreased, and CK5 protein levels increased, compared to controls treated with E alone. In ER+ tumors from patients treated with neoadjuvant endocrine therapies ER gene expression decreased, and CK5 gene expression increased in post compared to pre-treatment tumors. The number of CK5+ cells in tumors also increased in post- compared to pre-treatment tumors. We conclude that an ER−PR−CK5+ subpopulation found in many luminal tumors is resistant to standard endocrine and chemotherapies, relative to the majority ER+PR+CK5− cells. Compounds that effectively target these cells are needed to improve outcome in luminal breast cancers.

Dropout is a common problem in longitudinal cohort studies and clinical trials, often raising concerns of nonignorable dropout. Selection, frailty, and mixture models have been proposed to account for potentially nonignorable missingness by relating the longitudinal outcome to time of dropout. In addition, many longitudinal studies encounter multiple types of missing data or reasons for dropout, such as loss to follow-up, disease progression, treatment modifications and death. When clinically distinct dropout reasons are present, it may be preferable to control for both dropout reason and time to gain additional clinical insights. This may be especially interesting when the dropout reason and dropout times differ by the primary exposure variable. We extend a semi-parametric varying-coefficient method for nonignorable dropout to accommodate dropout reason. We apply our method to untreated HIV-infected subjects recruited to the Acute Infection and Early Disease Research Program HIV cohort and compare longitudinal CD4+ T cell count in injection drug users to nonusers with two dropout reasons: anti-retroviral treatment initiation and loss to follow-up.

BackgroundVery few studies have evaluated the duration of immunity of Bordetella bronchiseptica vaccines in dogs, and to date, no studies have been published on the duration of immunity of oral canine Bordetella bronchiseptica vaccines. This study was designed to determine the effectiveness of a single dose of an oral B bronchiseptica vaccine in dogs when challenged 13 months after vaccination.MethodsTwo groups of approximately eight-week-old beagles were vaccinated once with 1 ml of placebo vaccine (oral, n=17) or 1 ml of Recombitek Oral Bordetella (oral, n=17). Thirteen months after vaccination, both groups were challenged with virulent B bronchiseptica via aerosolisation.ResultsThirteen of 17 dogs in the placebo group (76.5 per cent) and no dogs in the Recombitek Oral Bordetella vaccine group (0.0 per cent) developed spontaneous cough of two or more consecutive days (disease case definition). Dogs in the Recombitek Oral Bordetella group had a significantly lower prevalence of disease with prevented fraction of 1 (100 per cent prevention). In addition, the number of days coughing, duration of cough and prevalence of tracheal and nasal shedding were significantly lower for dogs vaccinated with Recombitek Oral Bordetella.ConclusionsThe study demonstrated that vaccination with Recombitek Oral Bordetella is effective in preventing disease and reducing shedding 13 months after vaccination when compared with dogs vaccinated with a placebo.