title: Comparative safety, pharmacokinetic and pharmacodynamic evaluation of three oral selenium compounds in cancer patients

authors: Evans, Stephen Owen

subjects: Selenium

abstract: Selenium (Se) is an essential trace element involved in many biological processes in humans. Se compounds have demonstrated growth inhibition of malignant cells and tumours in many experimental models. Furthermore, combining Se with cancer therapies has yielded promising results in both preclinical studies and human trials, where reduced toxicity and enhanced anti-tumour efficacy is reported. However the optimal form and dose of Se in combination with anticancer therapies in terms of safety and efficacy has yet to be established, with particular concern about possible second malignancies due to DNA-damaging properties of both high-dose Se compounds and cancer therapies.
A key component of the toxicological study of new compounds is the assessment of their genotoxic potential. To achieve this a quantitative polymerase chain reaction-based method was developed that measured DNA damage within regions of nuclear and mitochondrial DNA relative to untreated controls, this assay was then validated in cancer cells and peripheral blood mononuclear cells (PBMCs). Subsequently, the method was optimised on a newly-acquired qPCR platform (Magnetic induction cycler) and used for measuring DNA damage in the clinical trial.
The primary research objective of determining the optimal form and dose of Se to be used alongside anticancer therapies was addressed through a randomised, double-blinded clinical trial. The safety, tolerability and pharmacokinetic (PK) and pharmacodynamic (PD) profiles of sodium selenite (SS), Se-methylselenocysteine (MSC) and seleno-l-methionine (SLM) were compared in patients with chronic lymphocytic leukaemia (CLL) and a cohort of patients with metastatic solid cancers. Patients received 400g of elemental Se orally, as SS, MSC or SLM, for 8 weeks. Safety evaluations and bloods for PK and PD analyses were taken twice prior to treatment and at Days 2, 28 (week 4), 56 (week 8) and 84 (week 12) from commencing treatment. Each Se compound group (n=8) included four patients with CLL and four with solid cancers.
Twenty-four patients were treated and all Se compounds were well-tolerated, with no grade 3-4 toxicities attributed to the study drugs. The baseline-corrected area under the concentration-time curve for plasma Se was markedly higher with SLM than MSC or SS, consistent with previous reports. Assessment of DNA damage in normal and malignant PBMCs revealed negligible genotoxicity. In CLL patients, no fall in blood lymphocyte count was seen in those treated with SS, whereas the majority of those treated with SLM or MSC showed a reduction, with one patient achieving a partial response. Persistent reductions in plasma VEGF were observed in 7/12 patients with CLL and 4/12 with solid cancers. Minimal changes were observed in intracellular glutathione or markers of the endoplasmic reticulum stress response.
In conclusion, Se compounds are well-tolerated and non-genotoxic at this dose. A reduction in plasma VEGF occurred at lower doses than predicted whereas changes in ER stress markers and intracellular glutathione are consistent with the dose-response seen in tumour xenografts and cell lines. Evaluation of these compounds at the higher doses of 1600g and 6400g per day, where PD effects are predicted to be greater, is planned for a future study.

text: Comparative safety, pharmacokinetic and pharmacodynamic evaluation of three oral selenium compounds in cancer patients Selenium (Se) is an essential trace element involved in many biological processes in humans. Se compounds have demonstrated growth inhibition of malignant cells and tumours in many experimental models. Furthermore, combining Se with cancer therapies has yielded promising results in both preclinical studies and human trials, where reduced toxicity and enhanced anti-tumour efficacy is reported. However the optimal form and dose of Se in combination with anticancer therapies in terms of safety and efficacy has yet to be established, with particular concern about possible second malignancies due to DNA-damaging properties of both high-dose Se compounds and cancer therapies.
A key component of the toxicological study of new compounds is the assessment of their genotoxic potential. To achieve this a quantitative polymerase chain reaction-based method was developed that measured DNA damage within regions of nuclear and mitochondrial DNA relative to untreated controls, this assay was then validated in cancer cells and peripheral blood mononuclear cells (PBMCs). Subsequently, the method was optimised on a newly-acquired qPCR platform (Magnetic induction cycler) and used for measuring DNA damage in the clinical trial.
The primary research objective of determining the optimal form and dose of Se to be used alongside anticancer therapies was addressed through a randomised, double-blinded clinical trial. The safety, tolerability and pharmacokinetic (PK) and pharmacodynamic (PD) profiles of sodium selenite (SS), Se-methylselenocysteine (MSC) and seleno-l-methionine (SLM) were compared in patients with chronic lymphocytic leukaemia (CLL) and a cohort of patients with metastatic solid cancers. Patients received 400g of elemental Se orally, as SS, MSC or SLM, for 8 weeks. Safety evaluations and bloods for PK and PD analyses were taken twice prior to treatment and at Days 2, 28 (week 4), 56 (week 8) and 84 (week 12) from commencing treatment. Each Se compound group (n=8) included four patients with CLL and four with solid cancers.
Twenty-four patients were treated and all Se compounds were well-tolerated, with no grade 3-4 toxicities attributed to the study drugs. The baseline-corrected area under the concentration-time curve for plasma Se was markedly higher with SLM than MSC or SS, consistent with previous reports. Assessment of DNA damage in normal and malignant PBMCs revealed negligible genotoxicity. In CLL patients, no fall in blood lymphocyte count was seen in those treated with SS, whereas the majority of those treated with SLM or MSC showed a reduction, with one patient achieving a partial response. Persistent reductions in plasma VEGF were observed in 7/12 patients with CLL and 4/12 with solid cancers. Minimal changes were observed in intracellular glutathione or markers of the endoplasmic reticulum stress response.
In conclusion, Se compounds are well-tolerated and non-genotoxic at this dose. A reduction in plasma VEGF occurred at lower doses than predicted whereas changes in ER stress markers and intracellular glutathione are consistent with the dose-response seen in tumour xenografts and cell lines. Evaluation of these compounds at the higher doses of 1600g and 6400g per day, where PD effects are predicted to be greater, is planned for a future study.

year: 2019

title: Indole diterpenoid secondary metabolites produced by the Epichloë festucae var. lolii – Lolium perenne symbiosis.

authors: Kaufononga, Sangata Ana Fiealu

abstract: The indole diterpenoid intermediates of lolitrems in a crude extract of Lolium perenne (L. perenne) seed infected with Epichloë festucae var. lolii (E. festucae var. lolii) and their biological activity against porina larvae were investigated.

Liquid-liquid partitioning of the crude extract, together with a series of bench columns (normal and reversed phase) and semi-preparative High Performance Liquid Chromatography (HPLC) yielded the novel compounds A – D (64 – 67).

Mass spectrometry (MS) and Nuclear Magnetic Resonance (NMR) spectroscopy were used to determine the structures of these alkaloids. The indole moiety of known indole diterpenoids was modified to a six-membered ring in the novel compounds A – D (64 – 67), with the right side of these molecules similar to that of lolitrem B (3) and terpendole C (49). Compounds A – D (64 – 67) differ in the stereochemistry and substituent at C-2. The structural features of these compounds are very unusual. These contain a spiro centre that fuses the modified indole region to the right side, indicating that they may be artefacts rather than naturally occurring, which in turn, could explain why they are not detectable in the Liquid Chromatography Mass Spectrometry (LC-MS) analysis of fresh extract. However, further work would be required to confirm this. 

The known alkaloids, terpendole D (50), 13-desoxypaxilline (37) and paspaline (42) were also isolated, together with a potential emindole analogue. This is the first report of terpendole D (50) from this ryegrass-endophyte association. The presence of an emindole analogue suggested that further intermediates are yet to be isolated from this association as indicated in the LC MS analysis of the crude extract. However, due to the scarcity of the emindole analogue, complete structural confirmation was not possible.

The biological activity of paxilline (36), lolitrem B (3), 13-desoxypaxilline (37), paspaline (42), terpendole D (50) and compounds A (64) and B (65) on porina larvae was determined using a semi-synthetic diet feeding bioassay. These compounds had not been previously tested on porina. Paxilline (36) had a dose-dependent effect on both food consumption and larval weight. Diet consumption and weight gain of porina larvae were significantly reduced by paxilline at concentrations of  2.5, 5 and 10 μg/g but not at concentrations of 1.0 μg/g, compared to dimethyl sulfoxide (DMSO) solvent control diet. Lolitrem B (3) had a similar effect on consumption and weight gain to that of paxilline (36) at concentrations of 5 and 10 μg/g but there was no indication that 13-desoxypaxilline (37), terpendole D (50), paspaline (42), compound A (64) or compound B (65) reduced feeding by porina larvae.

text: Indole diterpenoid secondary metabolites produced by the Epichloë festucae var. lolii – Lolium perenne symbiosis. The indole diterpenoid intermediates of lolitrems in a crude extract of Lolium perenne (L. perenne) seed infected with Epichloë festucae var. lolii (E. festucae var. lolii) and their biological activity against porina larvae were investigated.

Liquid-liquid partitioning of the crude extract, together with a series of bench columns (normal and reversed phase) and semi-preparative High Performance Liquid Chromatography (HPLC) yielded the novel compounds A – D (64 – 67).

Mass spectrometry (MS) and Nuclear Magnetic Resonance (NMR) spectroscopy were used to determine the structures of these alkaloids. The indole moiety of known indole diterpenoids was modified to a six-membered ring in the novel compounds A – D (64 – 67), with the right side of these molecules similar to that of lolitrem B (3) and terpendole C (49). Compounds A – D (64 – 67) differ in the stereochemistry and substituent at C-2. The structural features of these compounds are very unusual. These contain a spiro centre that fuses the modified indole region to the right side, indicating that they may be artefacts rather than naturally occurring, which in turn, could explain why they are not detectable in the Liquid Chromatography Mass Spectrometry (LC-MS) analysis of fresh extract. However, further work would be required to confirm this. 

The known alkaloids, terpendole D (50), 13-desoxypaxilline (37) and paspaline (42) were also isolated, together with a potential emindole analogue. This is the first report of terpendole D (50) from this ryegrass-endophyte association. The presence of an emindole analogue suggested that further intermediates are yet to be isolated from this association as indicated in the LC MS analysis of the crude extract. However, due to the scarcity of the emindole analogue, complete structural confirmation was not possible.

The biological activity of paxilline (36), lolitrem B (3), 13-desoxypaxilline (37), paspaline (42), terpendole D (50) and compounds A (64) and B (65) on porina larvae was determined using a semi-synthetic diet feeding bioassay. These compounds had not been previously tested on porina. Paxilline (36) had a dose-dependent effect on both food consumption and larval weight. Diet consumption and weight gain of porina larvae were significantly reduced by paxilline at concentrations of  2.5, 5 and 10 μg/g but not at concentrations of 1.0 μg/g, compared to dimethyl sulfoxide (DMSO) solvent control diet. Lolitrem B (3) had a similar effect on consumption and weight gain to that of paxilline (36) at concentrations of 5 and 10 μg/g but there was no indication that 13-desoxypaxilline (37), terpendole D (50), paspaline (42), compound A (64) or compound B (65) reduced feeding by porina larvae.

year: 2019

title: Exploring synergies between Māori pedagogy and communicative language teaching

authors: Nock, Sophie

subjects: Māori pedagogy

abstract: The primary aim of this paper is to explore potential synergies between Māori pedagogy and what is known as ‘communicative language teaching’. A brief outline of some changes and developments in approaches to language teaching and learning over the last few decades is followed by a summary of some of the main characteristics of communicative language teaching (CLT) and of different approaches to the conceptualization of Māori pedagogy. Some of the primary characteristics of communicative language teaching are then explored in the context of Māori pedagogy and it is argued that there are some important synergies between the two.

text: Exploring synergies between Māori pedagogy and communicative language teaching The primary aim of this paper is to explore potential synergies between Māori pedagogy and what is known as ‘communicative language teaching’. A brief outline of some changes and developments in approaches to language teaching and learning over the last few decades is followed by a summary of some of the main characteristics of communicative language teaching (CLT) and of different approaches to the conceptualization of Māori pedagogy. Some of the primary characteristics of communicative language teaching are then explored in the context of Māori pedagogy and it is argued that there are some important synergies between the two.

year: 2009-02