The PI3-K/AKT/mTOR pathway as a target for breast cancer therapy

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Background: The PI3K/Akt/mTOR pathway is found dysregulated in multiple tumours, including breast cancer (BC). RAD001 is a recently developed drug which blocks mTOR. To study this compound’s anti-tumour effect and interactions with the aforementioned pathway, we set up a translational research program which integrates basic and clinical research data. Methods: The preclinal studies performed in BC cell lines and xenografts included the use of proliferation assays, western blot (WB), small interfering RNA and immunohistochemistry (IHC) analysis. The clinical studies consisted in a phase I study with escalating doses and collection of tumour biospies at different time points Results: Our first achievement was validating the antibodies used in WB and IHC and directed towards different components of the PI3K/Akt/mTOR pathway. We first reported that sensitivity to RAD001 correlated to basal levels of p-Akt. We then observed that RAD001 inhibits mTOR downstream, pS6 and eIF4G, but increases the levels of p-Akt, both in vitro and in patients’tumour biopsies. We demonstrated that knock down of the pS6 kinase mimics the effect of RAD001. Indeed, by combining the PI3K inhibitors and the genomic approch of p85 dominant negative vector, we demonstrated that RAD001 induced p-Akt is through PI3K. Besides the p-Akt induction we also found a RAD001 induction of IRS-1, the pivot mediator of the Insulin like Growth factor-1 Receptor (IGF-1R). We reported that RAD001 resulted in a prolonged activation of IRS-1 and in a sustained association with the p85 subunit of PI3K. Thus RAD001 disrupts an inhibitory mechanism impinging on the PI3K signalling, resulting in sustained activation of the IGF-1R pathway. Accordingly we demonstrated that combination of RAD001 with coumpounds directed against the IGF-1R, i.e. both IGF-1R tyrosine kinase inhibitors and monoclonal antibodies, prevented RAD001 induced p-Akt and resulted in a supradditive growth inhibitory effects both in vitro and in MCF-7 human BC derived xenografts.We are now conducting a phase I study with a monoclonal antibody directed at the IGF-1R that blocks IGF-1R signalling. Conclusions: Dual inhibition of mTOR and IGF-1R completely blocks the PI3K/Akt/mTOR pathway and provide a mechanistic-based combined approach. Clinical studies in BC patients are being planned.

No significant financial relationships to disclose.

Prevalence of Toxoplasma gondii in cats from Colombia, South America and genetic characterization of T. gondii isolates

Cats are important in the epidemiology of Toxoplasma gondii infection because they are the only hosts that can excrete the environmentally-resistant oocysts. In the present study, prevalence of T. gondii was determined in serum, feces, and tissues of 170 unwanted cats from Colombia, South America. Antibodies to T. gondii were assayed by the modified agglutination test and found in 77 of 170 (45.2%) cats with titers of <1:5 in 93, 1:5 in eight, 1:10 in 17, 1:20 in 10, 1:40 in seven, 1:80 in four, 1:160 in eight, 1:320 in six, and 1:640 or higher in 17 cats. T. gondii oocysts were not found in feces of any cat as ascertained by bioassay in mice. Tissues (brain, heart, tongue) of 116 cats were bioassayed in mice or cats. T. gondii was isolated from tissues of 15 of the 42 cats with titers of 1:40 or higher and not from any of the 90 cats titers of 1:20 or lower. Of the 29 cats whose tissues were bioassayed individually, T. gondii was isolated from the tongues of nine, hearts of eight, and brains of five. Mice inoculated with tissues of 12 of 15 infected cats died of toxoplasmosis; with nine T. gondii isolates all infected mice died. Overall, 65 of 92 (70%) of T. gondii-infected mice died of toxoplasmosis. Genotyping of these 15 isolates using polymorphisms at the SAG1, SAG2, SAG3, BTUB, and GRA6 loci revealed that three isolates (TgCtCo1, 2, and 7) had Type I alleles and one isolate (TgCtCo8) had Type II allele at all five loci. Eleven isolates contained the combination of Type I and III alleles and were divided into three genotypes, with TgCtCo3,5,6,9,12,13 and 15 had alleles I, I, III, I and III, TgCtCo4,10,11 had alleles I, III, III, I and I, and TgCtCo14 had alleles I, III, III, III, and III, at loci SAG1, SAG2, SAG3, BTUB and GRA6, respectively. All infected mice from each group had identical genotype except one mouse infected with TgCtCo5 had a Type III allele at locus BTUB and a unique allele (u-1) at locus SAG1 indicating mixed infection for TgCtCo5, whereas the rest seven mice had a Type I alleles at both loci.

Antibiotic Prescription for Community-Acquired Pneumonia in the Intensive Care Unit: Impact of Adherence to Infectious Diseases Society of America Guidelines on Survival

BACKGROUND

The purpose of our study was to analyze prognostic factors associated with mortality for patients with severe community-acquired pneumonia (CAP).

METHODS

We conducted a prospective multicenter study including all patients with CAP admitted to the intensive care unit during a 15-month period in 33 Spanish hospitals. Admission data and data on the evolution of the disease were recorded. Multivariate analysis was performed using the SPSS statistical package (SPSS).

RESULTS

A total of 529 patients with severe CAP were enrolled; the mean age (+/-SD) was 59.9+/-16.1 years, and the mean Acute Physiology and Chronic Health Evaluation (APACHE) II score (+/-SD) was 18.9+/-7.4. Overall mortality among patients in the intensive case unit was 27.9% (148 patients). The rate of adherence to Infectious Diseases Society of America (IDSA) guidelines was 57.8%. Significantly higher mortality was documented among patients with nonadherence to treatment (33.2% vs. 24.2%). Multivariate analysis identified age (odds ratio [OR], 1.7), APACHE II score (OR, 4.1), nonadherence to IDSA guidelines (OR, 1.6), and immunocompromise (OR, 1.9) as the variables present at admission to the intensive care unit that were independently associated with death in the intensive care unit. In 15 (75%) of 20 cases of Pseudomonas aeruginosa infection, the antimicrobial treatment at admission was inadequate (including 8 of 15 cases involving patients with adherence to IDSA guidelines). Chronic obstructive pulmonary disease (OR, 17.9), malignancy (OR, 11.0), previous antibiotic exposure (OR, 6.2), and radiographic findings demonstrating rapid spread of disease (OR, 3.9) were associated with P. aeruginosa pneumonia.

CONCLUSIONS

Better adherence to IDSA guidelines would help to improve survival among patients with severe CAP. Pseudomonas coverage should be considered for patients with chronic obstructive pulmonary disease, malignancy, or recent antibiotic exposure.

Myocardial infarction risk in relation to zinc concentration in toenails

Zn is an essential mineral. The role of Zn in atherosclerosis is not clear. Epidemiological studies, which have reported contradictory results, are limited by the use of serum Zn levels as a marker of intake. We assessed the association of toenail Zn, which integrates dietary Zn intake over 3 to 12 months, with the risk of a first myocardial infarction. Toenail Zn concentrations were determined by neutron activation analysis in the European multi-centre case-control study on antioxidants, myocardial infarction and breast cancer. This multi-centre case-control study included 684 cases and 724 controls from eight European countries and Israel. Toenail Zn levels of controls (adjusted for age and study centre) were positively associated with age, alpha-tocopherol and Se, but not with additional dietary variables or with classical risk factors for CHD. Average toenail Zn was 106.0 mg/kg in cases (95 % CI 103.1, 108.9) and 107.5 mg/kg in controls (95 % CI 104.5, 110.7). After controlling for cardiovascular risk factors and for centre, the adjusted odds ratios of myocardial infarction for quintiles 2-5 of toenail Zn with respect to the first quintile were 0.97 (95 % CI 0.59, 1.58), 1.15 (95 % CI 0.72, 1.85), 0.91 (95 % CI 0.56, 1.50), and 0.85 (95 % CI 0.52, 1.39). The P for trend was 0.45. In conclusion toenail Zn levels (reflecting long-term dietary intake) were not significantly associated with acute myocardial infarction.