Discovery of Sulanemadlin (ALRN-6924), the First Cell-Permeating, Stabilized α-Helical Peptide in Clinical Development

We report the discovery of sulanemadlin (ALRN-6924), the first cell-permeating, stabilized α-helical peptide to enter clinical trials. ALRN-6924 is a "stapled peptide" that mimics the N-terminal domain of the p53 tumor suppressor protein. It binds with high affinity to both MDM2 and MDMX (also known as MDM4), the endogenous inhibitors of p53, to activate p53 signaling in cells having a non-mutant, or wild-type TP53 genotype (TP53-WT). Iterative structure-activity optimization endowed ALRN-6924 with favorable cell permeability, solubility, and pharmacokinetic and safety profiles. Intracellular proteolysis of ALRN-6924 forms a long-acting active metabolite with potent MDM2 and MDMX binding affinity and slow dissociation kinetics. At high doses, ALRN-6924 exhibits on-mechanism anticancer activity in TP53-WT tumor models. At lower doses, ALRN-6924 transiently arrests the cell cycle in healthy tissues to protect them from chemotherapy without protecting the TP53-mutant cancer cells. These results support the continued clinical evaluation of ALRN-6924 as an anticancer and chemoprotection agent.

First in class dual MDM2/MDMX inhibitor ALRN-6924 enhances antitumor efficacy of chemotherapy in TP53 wild-type hormone receptor-positive breast cancer models

BACKGROUND

MDM2/MDMX proteins are frequently elevated in hormone receptor-positive (ER+) breast cancer. We sought to determine the antitumor efficacy of the combination of ALRN-6924, a dual inhibitor of MDM2/MDMX, with chemotherapy in ER+ breast cancer models.

METHODS

Three hundred two cell lines representing multiple tumor types were screened to confirm the role of TP53 status in ALRN-6924 efficacy. ER+ breast cancer cell lines (MCF-7 and ZR-75-1) were used to investigate the antitumor efficacy of ALRN-6924 combination. In vitro cell proliferation, cell cycle, and apoptosis assays were performed. Xenograft tumor volumes were measured, and reverse-phase protein array (RPPA), immunohistochemistry (IHC), and TUNEL assay of tumor tissues were performed to evaluate the in vivo pharmacodynamic effects of ALRN-6924 with paclitaxel.

RESULTS

ALRN-6924 was active in wild-type TP53 (WT-TP53) cancer cell lines, but not mutant TP53. On ER+ breast cancer cell lines, it was synergistic in vitro and had enhanced in vivo antitumor activity with both paclitaxel and eribulin. Flow cytometry revealed signs of mitotic crisis in all treatment groups; however, S phase was only decreased in MCF-7 single agent and combinatorial ALRN-6924 arms. RPPA and IHC demonstrated an increase in p21 expression in both combinatorial and single agent ALRN-6924 in vivo treatment groups. Apoptotic assays revealed a significantly enhanced in vivo apoptotic rate in ALRN-6924 combined with paclitaxel treatment arm compared to either single agent.

CONCLUSION

The significant synergy observed with ALRN-6924 in combination with chemotherapeutic agents supports further evaluation in patients with hormone receptor-positive breast cancer.

Effect of enantiomerism on the bioequivalence of a new ibuprofen 600-mg tablet formulation obtained by roller compaction

The bioequivalence of a new ibuprofen 600-mg film-coated tablet obtained by roller compaction was studied in a crossover study with 22 healthy volunteers. Bioequivalence was analyzed based on (a) the S-enantiomer, (b) the R-enantiomer, and (c) the sum of both enantiomers (representing the results of an achiral assay). The bioequivalence conclusion for ibuprofen products should be based not only on AUC and Cmax but also on tmax since tmax is related to the onset of action. However, it is not possible to ensure if bioequivalence has been demonstrated for tmax as regulators have not defined the acceptance range for the difference between medians of tmax in those cases, where tmax is clinically relevant. In this study, it was possible to conclude bioequivalence for tmax based on S-ibuprofen, though this conclusion might be questioned if the decision is based on R-ibuprofen or the achiral method.

The Role of Colorectal Cancer Risk Chromosomal Regions in Colombian Admixed Populations

Background: Several colorectal cancer susceptibility disease loci have been discovered through genome-wide association studies. However most of the variants were originally identified in Caucasian populations. Aim: To analyze the role of 20 known risk SNPs for colorectal cancer. Methods: Given that linkage disequilibrium is highly dependent on population demographic history and admixture background, we studied 20 risk SNPs in a pooled sample of 955 cases and 968 controls from admixed populations in Colombia. Results: The replication was reached for 11 out of 20 nominally associated SNPs; with allelic odds ratios (OR) ranging from 1.14 to 1.41, indicating a minimal increase in risk individually, however coinheritance of those SNPs resulted in an overall OR = 5.4 (95% CI: 3.052-9.731, P = 1.16E−08). Most of the variants followed a recessive model consistent with significant homozygous ORs distributed between 1.3 and 1.65. Among the most associated markers we found: rs4939827 (18q21.1, P = 7.35E−6), rs10411210 (19q13.11, P = 0.001), rs10795668 (10p14, P = 0.0024), rs4444235 (14q.2.2, P = 0.005), rs961253 (20p12.3, P = 0.006), rs16892766 (8q23.3, P = 0.011) and rs1050547 (8q24.21, P = 0.017). Conclusion: Our findings in Colombia have addressed the admixture and how this has influenced the risk associated with the known/unknown colorectal cancer regions, providing a comprehensive vision about several CRC-susceptibility SNPs identified in European populations, which also resulted, associated with an increased risk to CRC in the Colombian population, even though frequency and genetic structure differences accounted for those nonreplicated SNPs.

Abstract C38: Novel allosteric IDH1 mutant Inhibitors for differentiation therapy of acute myeloid leukemia

Mutations in the isocitrate dehydrogenase 1 (IDH1) gene are known driver mutations in acute myeloid leukemia (AML) and other cancer types. AML is hallmarked by a differentiation block and patient outcomes remain poor, especially for patients above 60 years of age who typically do not tolerate high dose chemotherapy and stem cell transplantation, leading to cure rates below 20%. Hence the development of novel targeted therapies for treatment of AML subtypes are required. Of note, inhibitors of mutants of the closely related IDH2 gene as well as IDH1 have recently been described and show promising pre-clinical and early phase clinical activity. However, the specific molecular and functional effects of IDH1 inhibitors in AML, including in primary patients' cells, have not been reported yet.

Here, we report the development of novel allosteric inhibitors of mutant IDH1 for differentiation therapy of acute myeloid leukemia. A high-throughput biochemical screen targeting an IDH1 heterodimer composed of R132H and WT IDH1 led to the identification of a tetrahydropyrazolopyridine series of inhibitors. Structural and biochemical analyses revealed that these novel compounds bind to an allosteric site that does not contact any of the mutant residues in the enzymes active site and inhibit enzymatic turnover. The enzyme complex locked in the catalytically inactive conformation inhibits the production of the oncometabolite 2-hydroxyglutarate (2-HG). In biochemical studies, we observed potent inhibition of several different clinically relevant R132 mutants in the presence or absence of the cofactor NADPH, accompanied by significant decrease in H3K9me2 levels.

Treatment of primary IDH1 mutant AML patients' cells ex vivo uniformly led to a decrease in intracellular 2-HG, abrogation of the myeloid differentiation block, increased cell death and induction of differentiation both at the level of leukemic blasts and immature stem-like cells. Allosteric inhibition of IDH1 also led to a decrease in leukemic blasts in an in vivo xenotransplantation model. At the molecular level, enhanced reduced representation bisulfite sequencing showed that treatment with allosteric IDH1 inhibitors led to a significant reversal of the DNA cytosine hypermethylation pattern induced by mutant IDH1, accompanied by gene expression changes of key sets of genes and pathways, including “Cell Cycle”, “G1/S transition”, “Cellular growth and proliferation”, and “Cell death and survival”.

Taken together, our findings provide novel insight into the effects of inhibition of mutant IDH1 in primary AML patients' cells and open avenues for future investigations with these and other novel allosteric inhibitors for targeting IDH1 mutants in leukemia and possibly in other cancers.

Citation Format: Ujunwa C. Okoye-Okafor, Boris Bartholdy, Jessy Cartier, Enoch Gao, Beth Pietrak, Alan R. Rendina, Cynthia Rominger, Chad Quinn, Angela Smallwood, Ken Wiggall, Alexander Reif, Stan Schmidt, Hongwei Qi, Huizhen Zhao, Gerard Joberty, Maria Faelth-Savitski, Marcus Bantscheff, Gerard Drewes, Chaya Duraiswami, Pat Brady, Swathi-Rao Narayanagari, Ileana Antony-Debre, Kelly Mitchell, Heng Rui Wang, Yun-Ruei Kao, Maximilian Christopeit, Luis Carvajal, Laura Barreyro, Elisabeth Paietta, Britta Will, Nestor Concha, Nicholas D. Adams, Benjamin Schwartz, Michael T. McCabe, Jaroslav Maciejewski, Amit Verma, Ulrich Steidl. Novel allosteric IDH1 mutant Inhibitors for differentiation therapy of acute myeloid leukemia. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr C38.

New IDH1 mutant inhibitors for treatment of acute myeloid leukemia

Neomorphic mutations in isocitrate dehydrogenase 1 (IDH1) are driver mutations in acute myeloid leukemia (AML) and other cancers. We report the development of new allosteric inhibitors of mutant IDH1. Crystallographic and biochemical results demonstrated that compounds of this chemical series bind to an allosteric site and lock the enzyme in a catalytically inactive conformation, thereby enabling inhibition of different clinically relevant IDH1 mutants. Treatment of IDH1 mutant primary AML cells uniformly led to a decrease in intracellular 2-HG, abrogation of the myeloid differentiation block and induction of granulocytic differentiation at the level of leukemic blasts and more immature stem-like cells, in vitro and in vivo. Molecularly, treatment with the inhibitors led to a reversal of the DNA cytosine hypermethylation patterns caused by mutant IDH1 in the cells of individuals with AML. Our study provides proof of concept for the molecular and biological activity of novel allosteric inhibitors for targeting different mutant forms of IDH1 in leukemia.

Convergent linkage evidence from two Latin-American population isolates supports the presence of a susceptibility locus for bipolar disorder in 5q31-34

We performed a whole genome microsatellite marker scan in six multiplex families with bipolar (BP) mood disorder ascertained in Antioquia, a historically isolated population from North West Colombia. These families were characterized clinically using the approach employed in independent ongoing studies of BP in the closely related population of the Central Valley of Costa Rica. The most consistent linkage results from parametric and non-parametric analyses of the Colombian scan involved markers on 5q31-33, a region implicated by the previous studies of BP in Costa Rica. Because of these concordant results, a follow-up study with additional markers was undertaken in an expanded set of Colombian and Costa Rican families; this provided a genome-wide significant evidence of linkage of BPI to a candidate region of approximately 10 cM in 5q31-33 (maximum non-parametric linkage score=4.395, P<0.00004). Interestingly, this region has been implicated in several previous genetic studies of schizophrenia and psychosis, including disease association with variants of the enthoprotin and gamma-aminobutyric acid receptor genes.

Admixture dynamics in Hispanics: a shift in the nuclear genetic ancestry of a South American population isolate

Although it is well established that Hispanics generally have a mixed Native American, African, and European ancestry, the dynamics of admixture at the foundation of Hispanic populations is heterogeneous and poorly documented. Genetic analyses are potentially very informative for probing the early demographic history of these populations. Here we evaluate the genetic structure and admixture dynamics of a province in northwest Colombia (Antioquia), which prior analyses indicate was founded mostly by Spanish men and native women. We examined surname, Y chromosome, and mtDNA diversity in a geographically structured sample of the region and obtained admixture estimates with highly informative autosomal and X chromosome markers. We found evidence of reduced surname diversity and support for the introduction of several common surnames by single founders, consistent with the isolation of Antioquia after the colonial period. Y chromosome and mtDNA data indicate little population substructure among founder Antioquian municipalities. Interestingly, despite a nearly complete Native American mtDNA background, Antioquia has a markedly predominant European ancestry at the autosomal and X chromosome level, which suggests that, after foundation, continuing admixture with Spanish men (but not with native women) increased the European nuclear ancestry of Antioquia. This scenario is consistent with historical information and with results from population genetics theory.

Fast high performance liquid chromatography and ultraviolet–visible quantification of principal phenolic antioxidants in fresh rosemary

An improved HPLC method is reported for the determination of rosemary's principal phenolic antioxidants, rosmarinic and carnosic acids, providing a fast and simultaneous determination for both of them by using a solid phase column. The analysis was performed with fresh methanolic extractions of Rosmarinus officinalis. To quantify the amount of antioxidants in a fast and reproducible way by means of UV-vis absorption measurements, a spectrophotometric multi-wavelength calibration curve was constructed based on the antioxidant contents obtained with the recently developed HPLC method. This UV-vis methodology can be extended to the determination of other compounds and herbs if the restrictions mentioned in the text are respected.

Expression of Stat3 in germ cells of developing and adult mouse ovaries and testes

The Signal transducers and activators of transcription (Stat) family of proteins plays diverse roles during differentiation in many tissues. Stat3 is an essential mammalian gene, critical during embryonic development. In mammals, Stat3 is differentially distributed in the cytoplasm of mature oocytes and in preimplantation embryos suggesting that Stat3 may be involved in determination of polarity. Here, we report that Stat3 protein is expressed in the cytoplasm of oocytes from primordial, primary and secondary follicles in the adult ovary and in developing acrosomes of round spermatids in the adult testis. Stat3 is also expressed in gonocytes, prospermatogonia, oogonia and oocytes of embryonic and neonatal gonads.

[Extended-spectrum beta-lactamases in Klebsiella pneumoniae isolated at the Cordoba Children's Hospital, Argentina]

The aim of the present study was to investigate the presence of extended-spectrum beta-lactamases (ESBL) in Klebsiella pneumoniae isolated at the "Hospital de Niños de Córdoba". The strains were collected from inpatients between January 1996 and July 2000. A total of 150 ESBL producer isolates were detected. During 1996 the prevalence of ESBL producer K. pneumoniae was 20%, but since 1998 the values have increased to approximately 60%. Phenotypic analysis such as isoelectric point (pl) and antibiotyping performed in 32 randomly selected isolates showed two different enzyme profiles: 81% had ESBL with pl = 7.9 and preferential activity against cefotaxime, while 19% showed ESBL with pl = 5.4 and preferential activity against ceftazidime. No isolates resistant to imipenem or ciprofloxacin were detected. Susceptibility to other antimicrobial agents varied, but resistance to gentamicin was strongly associated with ESBL producer isolates. Resistance determinants could be transferred to Escherichia coli by conjugation assays.

[Streptococcus pneumoniae: evolution of antibiotic resistance in a pediatric hospital in Córdoba, Argentina]

The wide variety of prevalence of antimicrobial resistant Streptococcus pneumoniae in different countries confirms the importance of determining local patterns of resistance. From 1992 to 2000, we studied the pattern of antimicrobial resistance in S. pneumoniae and its evolution along the years, using 468 strains isolated in the Hospital de Niños de Córdoba. A total of 177 isolates (37.8%) were not susceptible to penicillin, with 19% intermediate and 18.8% resistant strains. High and intermediate resistance levels to cefotaxime were 4.9% and 10.9%, respectively. Decreased susceptibility to trimethoprim/sulfamethoxazole (TMS), erythromycin, chloramphenicol, and rifampin was found in 194 isolates (41.5%), 32 (6.8%), 13 (2.8%) and 3 (0.6%), respectively. No isolates resistant to vancomycin were detected. The most commonly combined resistance patterns were: penicillin/TMS (35.6%) and penicillin/TMS/cefotaxime (11.8%). This study highlights the increased rate of drug resistant S. pneumoniae during the last years, and the importance of antimicrobial resistance surveillance of adequate empirical therapy involving local and regional susceptibility patterns.

[Dilated cardiomyopathy in the ectodermal dysplasia. Electro-echocardiographic observations in palmo-plantar keratoderma with woolly hair]

Familial palmoplantar keratosis has not been associated with cardiac abnormalities, however, when this ectodermal dysplasia included hair shaft dystrophy a close association with cardiomyopathy was noted. We report here three family with six members in whom palmoplantar keratoderma with woolly hair and cardiac lesions was observed.

[Antimicrobial resistance of Shigella spp. in Córdoba, Argentina, during the period 1990-1997]

This study analyzed the evolution of antimicrobial resistance in 771 isolates of Shigella spp. obtained from a total of 9,195 feces cultures done between 1990 and 1997 in a children's hospital in Córdoba, Argentina. S. flexneri, which was responsible for 73% of the Shigella infections, was the species with the greatest resistance. The frequency of S. flexneri resistance to the three antibiotics most used (ampicillin, trimethoprim-sulfamethoxazole, and chloramphenicol) increased from 10% in 1990 to 58% in 1997 (P < 0.001). Considering each of the drugs individually, the resistance to ampicillin increased from 60% to 100% (P < 0.001), the resistance to chloramphenicol from 13% to 71% (P < 0.001), and the resistance to trimethoprim-sulfamethoxazole from 79% to 84% (P = 0.22). For S. sonnei, the increase in resistance to ampicillin (from 36% in 1990 to 54% in 1997) was not statistically significant (P = 0.20), nor was the reduction in resistance to trimethoprim-sulfamethoxazole, which went from 82% in 1990 to 55% in 1997 (P = 0.08). Only two S. sonnei isolates were found that were resistant to chloramphenicol, one in 1995 and another in 1997; two S. sonnei isolates were found with resistance to all three antibiotics. We consider it essential to carry out susceptibility tests of each Shigella clinical isolate, to detect changes in the resistance profile and thus modify empiric treatment.

Phased array detectors and an automated intensity-correction algorithm for high-resolution MR imaging of the human brain

Two- and four-coil phased array detectors were developed to increase the sensitivity and resolution of MR imaging of the human brain cortex, especially for detecting cortical dysplasias in pediatric epilepsy patients. An automated intensity correction algorithm based on an edge-completed, low-pass filtered image was used to correct the image intensity for the inhomogenous reception profile of the coils. Seven phased array coils were constructed and tested. The sensitivity of these coils was up to 600% higher at the surface of the cortex than that achieved with a conventional head coil and up to 30% greater at the center of the head. The sensitivity obtained was comparable with that of a conventional small surface coil, but extended over the larger dimensions of the array and previously inaccessible areas such as the top of the head. The advantages of the improved sensitivity are demonstrated with high resolution images of the brain.

Two configurations of the four-ring birdcage coil for 1H imaging and 1H-decoupled 31P spectroscopy of the human head

The four-ring birdcage resonator, a new class of dual-tuned birdcage resonators, is described. We report two configurations of the coil: the low-pass, high-pass (LP-HP) and the low-pass, low-pass (LP-LP), both of which can be operated in dual quadrature mode at 1.5 T. As head coils, both configurations exhibit greatly reduced tuning interactions between frequencies, permitting rapid, noniterative tuning. Compared with single-tuned, two-ring birdcage resonators of similar volume, the sensitivity and transmitter efficiencies of the resonators are better than 85% for the proton frequency and the same to within 5% for the phosphorus frequency. Circuit models have been developed to refine coil tuning and aid the calculation of B1 field contour plots. Both configurations have been used for integrated examinations involving acquisition of high-quality 1H images and 1H-decoupled 31P CSI spectra of the human head. A scaled-down version of the LP-LP configuration has been demonstrated for use with the human calf.

[Colorectal cancer. Experience in 120 patients]

The medical records of 120 patients with Colo-Rectal Cancer who were admitted between 1983 and 1990, were reviewed. The clinical, radiologic, epidemiologic, endoscopic and pathologic characteristic were analyzed in all the patients; also their follow up related to Age, CEA, Dukes and treatment. Late stage diagnosis (10.8% of the cases were diagnosed during obstructive episodes, and 48.3% of the cases were Dukes C and D) and the high mortality (34.1% of the patients died within the first year of the diagnosis), are still basic problems to be solved. The high percentage of patients less than 40 years old (25.8%) and the high incidence of rectal localization of the disease (49.1%), must prompt us to attempt to control the disease by means of colonic evaluation in young people with symptoms attributable to Hemorrhoids or Amebiasis.

1H MR imaging of anatomical compartments within the finger flexor muscles of the human forearm

Fast T2-weighted 1H MRI following exercise allows investigation of the location of muscle fiber activity within skeletal muscle. Using this method, we have demonstrated that the finger flexor muscles of the human forearm consist of anatomical compartments, located at various depths, which are involved individually in flexion of the index, middle, or ring and little fingers. The results of this study indicate that the exercise protocol in 31P MRS studies of the finger flexor muscles of the human forearm, in which a small surface coil is used for detection, should be carefully reviewed.