Direct comparison of the effects of intravenous kisspeptin-10, kisspeptin-54 and GnRH on gonadotrophin secretion in healthy men

STUDY QUESTION

How potently does the novel hypothalamic stimulator of reproduction, kisspeptin, increase gonadotrophin secretion when compared with GnRH in healthy men?

SUMMARY ANSWER

At the doses tested, intravenous administration of either of two major kisspeptin isoforms, kisspeptin-10 and -54, was associated with similar levels of gonadotrophin secretion in healthy men; however, GnRH was more potent when compared with either kisspeptin isoform.

WHAT IS KNOWN ALREADY

Kisspeptin-10 and -54 are naturally occurring hormones in the kisspeptin peptide family which potently stimulates endogenous GnRH secretion from the hypothalamus, so have the potential to treat patients with reproductive disorders. Rodent studies suggest that kisspeptin-54 is more potent when compared with kisspepitn-10; however, their effects have not previously been directly compared in humans, or compared with direct pituitary stimulation of gonadotrophin secretion using GnRH.

STUDY DESIGN, SIZE AND DURATION

A single-blinded placebo controlled physiological study was performed from January to December 2013. Local ethical approval was granted, and five participants were recruited to each dosing group.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Healthy men were administered vehicle, kisspeptin-10, kisspeptin-54 and GnRH intravenously for 3 h on different study days. Each hormone was administered at 0.1, 0.3 and 1.0 nmol/kg/h doses (n = 5 subjects per group). Regular blood sampling was conducted throughout the study to measure LH and FSH. Study visits were conducted at least a week apart.

MAIN RESULTS AND THE ROLE OF CHANCE

Serum LH and FSH levels were ∼3-fold higher during GnRH infusion when compared with kisspeptin-10 and ∼2-fold higher when compared with kisspeptin-54 [mean area under the curve serum LH during infusion (in hours times international units per litre, h.IU/l): 10.81 ± 1.73, 1.0 nmol/kg/h kisspeptin-10; 14.43 ± 1.27, 1.0 nmol/kg/h kisspeptin-54; 34.06 ± 5.18, 1.0 nmol/kg/h GnRH, P < 0.001 versus kisspeptin-10, P < 0.01 versus kisspeptin-54].

LIMITATIONS, REASONS FOR CAUTION

This study had a small sample size.

WIDER IMPLICATIONS OF THE FINDINGS

Kisspeptin offers a novel means of stimulating the reproductive axis. Our data suggest that kisspeptin stimulates gonadotrophin secretion less potently when compared with GnRH; however, kisspeptin may stimulate gonadotrophins in a more physiological manner when compared with current therapies. Kisspeptin is emerging as a future therapeutic agent, so it is important to establish which kisspeptin hormones could be used to treat patients with infertility. Results of this study suggest that either isoform has similar effects on reproductive hormone secretion in healthy men when administered intravenously.

STUDY FUNDING/COMPETING INTERESTS

This work is funded by grants from the MRC and NIHR and is supported by the NIHR Imperial Biomedical Research Centre Funding Scheme. C.N.J. is supported by an NIHR Clinical Lectureship. A.A. is supported by Wellcome Trust Research Training Fellowships. A.N.C. is supported by Wellcome Trust Translational Medicine Training Fellowship. W.S.D. is supported by an NIHR Career Development Fellowship.

Phase II study of saracatinib (AZD0530) in patients with previously treated metastatic colorectal cancer

BACKGROUND

Src has a critical role in tumor cell migration and invasion. Increased Src activity has been shown to correlate with disease progression and poor prognosis, suggesting Src could serve as a therapeutic target for kinase inhibition. Saracatinib (AZD0530) is a novel selective oral Src kinase inhibitor.

METHODS

Metastatic colorectal cancer patients who had received one prior treatment and had measurable disease were enrolled in this phase 2 study. Saracatinib was administered at 175 mg by mouth daily for 28 day cycles until dose-limiting toxicity or progression as determined by staging every 2 cycles. The primary endpoint was improvement in 4 month progression-free survival. Design of Thall, Simon, and Estey was used to monitor proportion of patients that were progression free at 4 months. The trial was opened with plan to enroll maximum of 35 patients, with futility assessment every 10 patients.

RESULTS

A total of 10 patients were enrolled between January and November 2007. Further enrollment was stopped due to futility. Median progression-free survival was 7.9 weeks, with all 10 patients showing disease progression following radiographic imaging. Median overall survival was 13.5 months. All patients were deceased by time of analysis. Observed adverse events were notable for a higher than expected number of patients with grade 3 hypophosphatemia (n = 5).

CONCLUSION

Saracatinib is a novel oral Src kinase inhibitor that was well tolerated but failed to meet its primary endpoint of improvement in 4 month progression-free survival as a single agent in previously treated metastatic colorectal cancer patients.

Assessing pyloric sphincter pathophysiology using EndoFLIP in patients with gastroparesis

BACKGROUND

Pyloric dysfunction has been associated with gastroparesis, particularly diabetic gastroparesis. Endoscopic functional luminal imaging probe (EndoFLIP) uses 16 sensors inside a balloon that is inflated inside a sphincter to assess physiologic characteristics. The aim of this study was to measure the pressure, diameter, cross-sectional area (CSA), and distensibility of the pylorus using EndoFLIP in patients with gastroparesis. In addition, the relationship between pyloric pathophysiology with gastroparesis etiology, symptoms, and gastric emptying was assessed.

METHODS

EndoFLIP was performed in 54 patients (39 idiopathic gastroparesis, 15 diabetic gastroparesis). The EndoFLIP catheter was passed endoscopically so that the balloon straddled the pylorus. Pressure, diameter, CSA, and distensibility of the pylorus were measured at 20, 30, 40, and 50 cc balloon volume.

KEY RESULTS

Pyloric sphincter contour was seen best at 40 cc balloon distension (diameter 12.2 ± 0.44 mm, CSA 125.2 ± 9.15 mm(2), pressure 18.0 ± 1.23 mmHg, length 1.59 ± 0.34 cm, distensibility 10.7 ± 2.57 mm(2)/mmHg). There was a wide range seen in diameter (5.6-22.1 mm) and distensibility (1-55 mm(2)/mmHg) of the pylorus. Symptoms of early satiety and postprandial fullness were inversely correlated with pyloric sphincter diameter and CSA. No significant difference was seen between diabetic and idiopathic gastroparetics.

CONCLUSIONS & INFERENCES

EndoFLIP is a novel technique that can be used to assess pyloric physiologic characteristics. Early satiety and postprandial fullness were inversely correlated with diameter and CSA of the pyloric sphincter. No significant differences were seen comparing diabetic and idiopathic gastroparetics. This technology may be of benefit to help select patients with pyloric sphincter abnormalities.

Partner associations across sympatric broad-headed bug species and their environmentally acquired bacterial symbionts

Many organisms have intimate associations with beneficial microbes acquired from the environment. These host-symbiont associations can be specific and stable, but they are prone to lower partner specificity and more partner-switching than vertically transmitted mutualisms. To investigate partner specificity in an environmentally acquired insect symbiosis, we used 16S rRNA gene and multilocus sequencing to survey the bacterial population in the bacteria-harbouring organ (crypts) of 49 individuals across four sympatric broad-headed bug species (Alydus calcaratus, A. conspersus, A. tomentosus and Megalotomus quinquespinosus). Similar to other insect-bacteria associations, Burkholderia spp. were the most common residents of the crypts in all four insect species (77.2% of recovered sequences). Burkholderia presence was associated with prolonged survival to adulthood in A. tomentosus, suggesting a beneficial role of these specialized associations. Burkholderia were also found in environmental reservoirs in the insects' habitat, which may facilitate acquisition by insects by increasing Burkholderia-insect encounters. Symbiont establishment could also be facilitated by resistance to insect defences; zone of inhibition assays demonstrated that Burkholderia and other bacteria isolated from crypts are resistant to insect defences that limit growth of Escherichia coli. Alternatively, the insects' defences may not efficiently kill a broad range of bacteria. Although the symbiosis is targeted to Burkholderia, the insects' crypts housed other bacteria, including non-Burkholderiaceae species. There is no significant effect of host insect species on Burkholderia distribution, suggesting a lack of strong partner specificity at finer scales. The presence of frequent partner-switching between sympatric insects and their symbionts likely prevents tight co-evolutionary dynamics.

Preliminary Phase II Data Suggest That Entinostat (SNDX275), a Class 1 Selective Histone Deacetylase Inhibitor (HDACi), May Resensitize Breast Cancer Patients Progressing on Aromataste Inhibitor (AI) Therapy to Their AI Therapy

Background: Aromatase inhibitors (AI), reduce peripheral conversion of androgen to estrogen, and are standard treatment for ER+ breast cancer (BCA); however, despite initial benefit, the disease eventually progresses. Once patients become resistant to AI, cytotoxic chemotherapy is often used for palliation. Histone deacetylase inhibitors (HDACi) have been shown preclinically to reverse AI resistance and sensitize tumor to AI. Entinostat, an oral selective HDACi, reverses both de novo and acquired hormone resistance in BCA in cell lines and xenograph models and has been well-tolerated, in humans, as a single agent and in combination with other agents tested to date.Methods: Postmenopausal women with ER+ BCA progressing while receiving AI for &gt; 3 months were enrolled. Eligibility criteria included: measurable disease by RECIST criteria, PS 0 or 1, and ≤ 1 chemotherapy for metastatic disease. Exclusion criteria included: rapidly-progressing BCA, life-threatening metastases, chemotherapy within 3 months, and previous exposure to epigenetic modulating agents. Patients continued the AI therapy on which the cancer was progressing, with the addition of entinostat 5 mg weekly in 28-day cycles. Primary objective was to determine clinical benefit rate during the first 6 cycles, defined as the proportion of patients achieving CR, PR or SD lasting &gt; 6 months. Secondary objectives included ORR and PFS. Exploratory biomarkers for anti-tumor activities and entinostat pharmacology were also measured.Results: To date, 24 patients have been enrolled from October 2008 – May 2009. Interim results from 20 patients are described here. The median age is 69 yrs. Eight (40%) and 12 (60%) patients had ECOG scores of 0 and 1, respectively. Fifteen patients (80%) had received tamoxifen; 12 (60%) had prior chemotherapy or immunotherapy. Nine patients (45%) had visceral involvement (lung, pleura, and liver), and 10 had metastases to bone, 3 to breast, and 1 to skin. Among the 10 patients who have completed ≥ 2 cycles, preliminary analysis indicates that the longest durations of SD thus far are &gt; 6 months in 1 and &gt; 5 months in 2 patients. Preliminary analysis of biomarkers in paired samples from 6 patients indicates that HDAC inhibition correlates with changes in cellular molecular targets. Entinostat has been well-tolerated. The majority of AEs were mild to moderate in severity, and the character of AEs was generally consistent with that seen with AI therapy.Conclusion: Entinostat in combination with AI was well-tolerated in patients with progressive BCA. Disease stabilization in several patients was observed. At dose administered, expected pharmacological effects were achieved.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 6111.

Intracellular localization of photosensitizers

The intracellular localization of photosensitizers can be studied by different methods. One method involves homogenization of the cells followed by differential ultracentrifugation which leads to fractions enriched in nuclear, mitochondrial, and microsomal material as well as a supernatant fraction. More detailed information can be obtained by electron microscopy of cells exposed to light in the presence of photosensitizers. This method is based on the assumption that damage is primarily induced at intracellular sites where the concentration of photosensitizer is high. By irradiating the cells at 6 degrees C, where biochemical reactions are slow, and then incubating them for different times at 37 degrees C, it is possible to follow the development of damage. The amount of photosensitized damage to enzymes or cell functions whose localization in the cells is known gives information about the intracellular localization of the sensitizer. Fluorescence microscopy is the most direct method and is widely applicable because most photosensitizers fluoresce. Lipophilic dyes generally localize in membrane structures. In future more attention should be paid to the localization of dyes in lysosomes, as suggested by early reports. Mitochondria, the endoplasmic reticulum and nuclear membrane are other important loci for intracellular localization of sensitizers.