Sickle cell vaso-occlusion causes activation of iNKT cells that is decreased by the adenosine A2A receptor agonist regadenoson.

Adenosine A2A receptor (A2AR) agonists reduce invariant natural killer T (iNKT) cell activation and decrease inflammation in sickle cell disease (SCD) mice. We conducted a phase 1 trial of the A2AR agonist regadenoson in adults with SCD. The target dose was 1.44 µg/kg/h. iNKT cell activation was evaluated using antibodies targeting the p65 subunit of nuclear factor-κB (phospho-NF-κB p65), interferon-γ (IFN-γ), and A2AR. Regadenoson was administered to 27 adults with SCD. We examined 21 patients at steady state and 6 during painful vaso-occlusive crises (pVOC). iNKT cell activation was also measured in 14 African-American controls. During pVOC, the fraction of iNKT cells demonstrating increased phospho-NF-κB p65 and A2AR expression was significantly higher compared with controls (P < .01) and steady-state patients (P < .05). IFN-γ expression was also significantly higher compared with controls (P = .02). After a 24-hour infusion of regadenoson during pVOC, phospho-NF-κB p65 activation in iNKT cells decreased compared to baseline by a median of 48% (P = .03) to levels similar to controls and steady-state SCD. No toxicities were identified. Infusional regadenoson administered to adults with SCD at 1.44 µg/kg/h during pVOC decreases activation of iNKT cells without toxicity.

Comparative rates of adverse events with different formulations of intravenous iron.

Oral iron replacement is the standard therapy in iron-deficiency anemia (IDA). However, 59% of patients have gastrointestinal toxicity. With impaired iron uptake from the gastrointestinal tract (in anemia of chronic disease (ACD) or after bariatric surgery), suboptimal responsiveness to exogenous erythropoietin (in chronic renal failure), in patients with cancer receiving chemotherapy, or when oral iron is poorly tolerated, IV iron therapy is the preferred mode of repletion. Although effective in increasing hemoglobin, the relative safety of the available IV iron preparations is not well documented. We examined the comparative safety of IV iron formulations used at hospitals associated with our institution. Among 619 unique patients who received IV iron over a 2-year period, we found 32 adverse events (AEs), ranging from urticaria to chest pain. There were no serious AEs or anaphylactic-type reactions. In a multivariate model, there was no difference in AE rates between low-molecular-weight iron dextran (LMWD) and ferric gluconate; however, iron sucrose had significantly higher odds ratio of AEs (OR = 5.7; 95% CI = 1.6­21.3). Our data suggest that AE rates with IV iron are acceptable. More widespread use of LMWD, in particular, which can be given safely as a total dose infusion (TDI), should be considered.

Sickle cell disease (SCD), iNKT cells, and regadenoson infusion.

A humanized murine sickle cell-disease (SCD) model (NY1DD) has been used to study ischemia/reperfusion injury (IRI) in sickle cell anemia, and iNKT cells (a very small subset of murine and human T cells) have been found to instigate such injury in this model. Furthermore, levels of activated iNKT cells are generally elevated in the circulation of patients with SCD. Because activated iNKT cells are rich in adenosine A2A receptors which, when agonized, down-regulate the inflammatory cytokine expression that characterizes the cells, we have conducted a phase 1 trial of a constant infusion of low-dose regadenoson (an adenosine analogue with high A2A receptor specificity) to determine its safety and the capacity of a safe dose to down-regulate circulating iNKT cells in patients with SCD. We have found two dose rates that are both safe and effective and now plan a controlled Phase 2B clinical trial to determine whether our highest dose, administered as a 48-hour constant infusion, will induce faster remission in both painful vaso-occlusive crisis (pVOC) and acute chest syndrome (ACS).

An exploratory survival analysis of anti-angiogenic therapy for recurrent malignant glioma.

Recent clinical trial results suggest that anti-angiogenic therapy may be effective against recurrent malignant glioma. Though these treatments prolong progression-free survival, the extent to which they prolong overall survival is unknown. We pooled data from 34 patients treated at a single institution on phase II clinical trials of bevacizumab and cediranib, and we compared these data to 18 patients treated on clinical trials of cytotoxic chemotherapies. In univariate and multivariate analyses, treatment group was a significant predictor of progression-free but not overall survival. Median progression-free survival was 8 vs. 22 weeks in patients treated with cytotoxic as compared to anti-angiogenic therapy (P = 0.01). Median overall survival was nearly identical in the two groups (39 vs. 37 weeks). The results of this exploratory analysis suggest that anti-angiogenic therapy may fail to prolong overall survival in patients with recurrent malignant glioma. If this conclusion proves correct, progression-free survival may be an inappropriate endpoint for phase II trials of anti-angiogenic therapies.