Exposure-Safety Analyses of Talazoparib in Patients With Advanced Breast Cancer and Germline BRCA1/2 Mutations in the EMBRACA and ABRAZO Trials.

Poly(ADP-ribose) polymerase inhibitors, such as talazoparib, may affect hematopoiesis. This analysis characterized the relationship between talazoparib exposure and the most common grade ≥ 3 hematopoietic adverse events (AEs) leading to dose modification in the phase 2 (ABRAZO) and phase 3 (EMBRACA) trials. The relationship between time-varying average talazoparib concentration (Cavg,t ), along with other baseline variables, and grade ≥ 3 anemia, thrombocytopenia, and neutropenia were evaluated both by graphical examination and using univariate and multivariate Cox proportional hazard models. The results indicated that higher Cavg,t was associated with a higher risk of anemia and thrombocytopenia. A trend toward an association between higher Cavg,t and neutropenia was observed, although not statistically significant. Higher risk of all tested safety end points was associated with lower baseline hemoglobin. Higher risk of neutropenia was associated with lower baseline absolute neutrophil count and lower body weight. These findings support the proposed management of AEs through talazoparib dosing modification.

Effect of co-administration of varenicline and antidepressants on extracellular monoamine concentrations in rat prefrontal cortex.

Since a substantial proportion of smokers have comorbid mood disorders, the smoking cessation aid varenicline might occasionally be prescribed to patients who are simultaneously treated with antidepressants. Given that varenicline is a selective nicotinic acetylcholine receptor partial agonist and not a substrate or inhibitor of drug metabolizing enzymes, pharmacokinetic interactions with various classes of antidepressants are highly unlikely. It is, however, conceivable that varenicline may have a pharmacodynamic effect on antidepressant-evoked increases in central monoamine release. Interactions resulting in excessive transmitter release could cause adverse events such as serotonin syndrome, while attenuation of monoamine release could impact the clinical efficacy of antidepressants. To investigate this we examined whether varenicline administration modulates the effects of the selective serotonin reuptake inhibitor sertraline and the monoamine oxidase inhibitor clorgyline, given alone and combined, on extracellular concentrations of the monoamines serotonin, dopamine, and norepinephrine in rat brain by microdialysis. Given the important role attributed to cortical monoamine release in serotonin syndrome as well as antidepressant activity, the effects on extracellular monoamine concentrations were measured in the medial prefrontal cortex. Responses to maximally effective doses of sertraline or clorgyline and of sertraline plus clorgyline were the same in the absence as in the presence of a relatively high dose of varenicline, which by itself had no significant effect on cortical monoamine release. This is consistent with the binding profile of varenicline that has insufficient affinity for receptors, enzymes, or transporters to inhibit or potentiate the pharmacologic effects of antidepressants. Since varenicline neither diminished nor potentiated sertraline- or clorgyline-induced increases in neurotransmitter levels, combining varenicline with serotonergic antidepressants is unlikely to cause excessive serotonin release or to attenuate antidepressant efficacy via effects on cortical serotonin, dopamine or norepinephrine release.