MO541HEMATOLOGIC EFFICACY OF VADADUSTAT FOR ANEMIA IN PATIENTS WITH NON--DIALYSIS-DEPENDENT CHRONIC KIDNEY DISEASE

Background and Aims

Vadadustat is a small-molecule inhibitor of hypoxia-inducible factor prolyl hydroxylases under development to treat anemia associated with chronic kidney disease (CKD). The vadadustat phase 3 program includes four efficacy and cardiovascular safety outcome trials of vadadustat versus the erythropoiesis-stimulating agent (ESA) darbepoetin alfa. Here we describe detailed results on hematologic efficacy in two phase 3, randomized trials (the PRO2TECT trials) in adult patients with non–dialysis-dependent (NDD) CKD and anemia, in which vadadustat met prespecified noninferiority criteria compared to darbepoetin alfa, with respect to hematologic efficacy (correction/maintenance of hemoglobin [Hb] target concentrations).

Method

The mean screening Hb level for the ESA-untreated NDD-CKD trial (NCT02648347) had to be <10.0 g/dL, and for the ESA-treated NDD-CKD trial (NCT02680574), the range had to be from 8.0-11.0 g/dL in the United States (US) and from 9.0-12.0 g/dL non-US. In the ESA-untreated trial, patients received no ESA within 8 weeks before randomization; in the ESA-treated trial, patients were maintained on ESA therapy, with ≥1 dose received within 6 weeks prior to or during screening. The vadadustat starting dose was 300 mg/day for all patients, whereas the initial darbepoetin alfa dose depended on each patient’s prior dose or the product label. Both vadadustat and darbepoetin alfa doses were titrated according to prespecified dosing algorithms to achieve target Hb concentrations (US: 10-11 g/dL; non-US: 10-12 g/dL) both during the primary (PEP; weeks 24-36) and secondary (SEP; weeks 40-52) evaluation periods. Herein, we present topline results from the PEP and SEP endpoints, in addition to more detailed erythrocyte parameters.

Results

A total of 3,476 patients (1751 ESA-untreated and 1725 ESA-treated) were randomized 1:1 to vadadustat or darbepoetin alfa. In both trials, vadadustat was noninferior to darbepoetin alfa with regard to the difference of mean change in Hb concentrations between baseline and PEP, as well as between baseline and SEP. The respective proportions of patients (vadadustat vs. darbepoetin alfa) with an average Hb value within the geography-specific target range in the PEP and SEP were 50.4% versus 50.2% and 43.1% versus 43.5% in the ESA-untreated trial and 60.1% versus 60.7% and 50.7% versus 49.0% in the ESA-treated trial. The proportion of patients (vadadustat vs darbepoetin alfa) who achieved an Hb increase >1.0 g/dL from baseline to week 52 was assessed only for the ESA-untreated trial and was 87.7% (95% CI: 85.4%, 89.8%) for vadadustat versus 88.0% (95% CI: 85.6%, 90.0%) for darbepoetin alfa.

Hematologic parameters at time points within the PEP and SEP are presented in Table 1. In both the ESA-untreated and ESA-treated trials, the reticulocyte count trended up from baseline through week 52 for vadadustat and trended down from baseline for darbepoetin alfa. Trends in erythrocyte mean corpuscular volume and erythrocyte mean corpuscular Hb were largely unremarkable by week 52 in both treatment groups.

Conclusion

Vadadustat demonstrated similar profiles across erythrocyte parameters compared with darbepoetin alfa in the treatment of adults with anemia in CKD not on dialysis, whether ESA-untreated or ESA-treated at study entry.

MO539HEMATOLOGIC EFFICACY OF VADADUSTAT FOR ANEMIA IN PATIENTS WITH KIDNEY FAILURE ON DIALYSIS

Background and Aims

Vadadustat is a small-molecule inhibitor of hypoxia-inducible factor prolyl hydroxylase being developed for treatment of anemia associated with chronic kidney disease (CKD). The vadadustat phase 3 program includes four efficacy and cardiovascular safety outcome trials of vadadustat versus the erythropoiesis-stimulating agent (ESA) darbepoetin alfa. Here we describe detailed results on hematologic efficacy in two of the four phase 3, randomized, open-label, sponsor-blind trials (the INNO2VATE trials) in adult patients with dialysis-dependent (DD) CKD and anemia, where vadadustat met prespecified noninferiority criteria compared with darbepoetin alfa with respect to cardiovascular safety and correction/maintenance of hemoglobin (Hb) target concentrations.

Method

The mean screening Hb range for the incident DD-CKD trial (NCT02865850) was 8.0-11.0 g/dL; for the prevalent DD-CKD trial (NCT02892149), it was 8.0-11.0 g/dL in the United States (US) and 9.0-12.0 g/dL for non-US. Patients in the incident and prevalent DD-CKD trials had initiated dialysis within <16 weeks with limited or no prior ESA exposure and >12 weeks with established ESA treatment prior to screening, respectively. Vadadustat starting dose was 300 mg/day for all patients, whereas initial darbepoetin alfa dose depended on each patient’s prior dose or product label. Both vadadustat and darbepoetin alfa doses were titrated according to prespecified dosing algorithms to achieve target Hb concentrations (US: 10-11 g/dL; non-US: 10-12 g/dL) during the primary evaluation period (PEP; weeks 24-36) and the secondary evaluation period (SEP; weeks 40-52). Herein, we present topline results from PEP and SEP endpoints, as well as other, more detailed hematologic erythrocyte parameters.

Results

A total of 3923 patients (369 with incident DD-CKD and 3554 with prevalent DD-CKD) were randomized 1:1 to vadadustat or darbepoetin alfa. Vadadustat was noninferior to darbepoetin alfa in achieving target-range Hb concentrations (primary efficacy endpoint) among patients who were new to, or established on, dialysis. The respective proportions of patients (vadadustat vs. darbepoetin alfa) with an average Hb value within the geography-specific target range in the PEP and SEP were 43.6% versus 56.9% and 39.8% versus 41.0% in the incident trial and 49.2% versus 53.2% and 44.3% versus 50.9% in the prevalent dialysis trial. The proportion of patients who achieved an Hb increase >1.0 g/dL from baseline to week 52 was assessed only for the incident trial and was 84.0% (95% CI: 77.8%, 89.0%) for vadadustat versus 89.9% (95% CI: 84.7%, 93.8%) for darbepoetin alfa.

Hematologic erythrocyte parameters at time points within the PEP and SEP are presented in Table 1. In the incident trial, reticulocyte count was slightly increased from baseline at 28 and 52 weeks for vadadustat, whereas for darbepoetin alfa, reticulocyte count was slightly decreased or unchanged in both trials. Erythrocyte mean corpuscular volume and erythrocyte mean corpuscular Hb showed increases by week 52 for both groups.

Conclusion

Vadadustat demonstrated similar profiles across erythrocyte parameters compared with darbepoetin alfa in the treatment of anemia associated with CKD in adults in both incident dialysis and prevalent dialysis settings.

Incidence of Immune Related Adverse Events in Patients Treated with Immune Checkpoint Inhibitors, Case Series from Two Tertiary Care Centeers in Dubai, UAE

Introduction:

Immune checkpoint inhibitors (ICI) represent a major component of systemic therapy in advanced malignancy. Studies have reported unique spectrum of toxicity profile of ICI as compared to systemic chemotherapy. Aim of this study is to evaluate toxicities of ICI in our population and to compare this with published data.

Material and Methods:

We retrospectively reviewed medical records of patients treated with ICI at Dubai hospital and American hospital Dubai from November 2015 to April 2019. After patient identification from hospitals cancer registry, data regarding patients’ demographics, cancer type, type of ICI, adverse events, and duration of treatment were collected.

Results:

Forty-Five patients were identified with median age of 60 (27-80) years. 27 (60%) patients were male and 18 (40%) were female. Underlying diagnosis was lung cancer (n=25), renal cell cancer (n=6), melanoma (n=5), bladder cancer (n=3), Hodgkins lymphoma (n=3) and other malignancies (n=3). Majority of patients received Nivolumab (n=20, 44%) followed by Pembrolizumab (n=19, 42%), Atezolizumab (n=4, 9%) and Durvalumab (n=2, 5%) respectively. Thyroid dysfunction was the most common side effect observed in 17 (38%) patients including hypothyroidism (n=12, 27%) and hyperthyroidism (n=5, 11%). 53 % patients treated with Nivolumab developed thyroid dysfunction as compared to Pembrolizumab (22%). 7 patients (16%) had elevated liver enzymes. Grade II and III hepatotoxicity was noted in 1 patient (2.2 %) each. One patient (2.2 %) developed grade II skin toxicity. One patient (2.2 %) developed grade III colitis. Grade II, III and IV pneumonitis was observed in 2 (4.4 %), 1 (2.2%) and 1 (2.2%) patient respectively. Immune mediated adverse events were managed according to standard guidelines and 2 patients (4.4 %) had treatment discontinuation due to grade IV Pneumonitis and grade III Colitis.

Conclusion:

Our study reports relatively higher incidence of thyroid adverse events in patients treated with ICI. The incidence of grade III-IV immune related toxicity remains low. Overall treatment with ICI was tolerated reasonably well and toxicity was manageable.

The Phosphate Binder Ferric Citrate and Mineral Metabolism and Inflammatory Markers in Maintenance Dialysis Patients: Results From Prespecified Analyses of a Randomized Clinical Trial

BACKGROUND

Phosphate binders are the cornerstone of hyperphosphatemia management in dialysis patients. Ferric citrate is an iron-based oral phosphate binder that effectively lowers serum phosphorus levels.

STUDY DESIGN

52-week, open-label, phase 3, randomized, controlled trial for safety-profile assessment.

SETTING & PARTICIPANTS

Maintenance dialysis patients with serum phosphorus levels ≥6.0 mg/dL after washout of prior phosphate binders.

INTERVENTION

2:1 randomization to ferric citrate or active control (sevelamer carbonate and/or calcium acetate).

OUTCOMES

Changes in mineral bone disease, protein-energy wasting/inflammation, and occurrence of adverse events after 1 year.

MEASUREMENTS

Serum calcium, intact parathyroid hormone, phosphorus, aluminum, white blood cell count, percentage of lymphocytes, serum urea nitrogen, and bicarbonate.

RESULTS

There were 292 participants randomly assigned to ferric citrate, and 149, to active control. Groups were well matched. For mean changes from baseline, phosphorus levels decreased similarly in the ferric citrate and active control groups (-2.04±1.99 [SD] vs -2.18±2.25 mg/dL, respectively; P=0.9); serum calcium levels increased similarly in the ferric citrate and active control groups (0.22±0.90 vs 0.31±0.95 mg/dL; P=0.2). Hypercalcemia occurred in 4 participants receiving calcium acetate. Parathyroid hormone levels decreased similarly in the ferric citrate and active control groups (-167.1±399.8 vs -152.7±392.1 pg/mL; P=0.8). Serum albumin, bicarbonate, serum urea nitrogen, white blood cell count and percentage of lymphocytes, and aluminum values were similar between ferric citrate and active control. Total and low-density lipoprotein cholesterol levels were lower in participants receiving sevelamer than those receiving ferric citrate and calcium acetate. Fewer participants randomly assigned to ferric citrate had serious adverse events compared with active control.

LIMITATIONS

Open-label study, few peritoneal dialysis patients.

CONCLUSIONS

Ferric citrate was associated with similar phosphorus control compared to active control, with similar effects on markers of bone and mineral metabolism in dialysis patients. There was no evidence of protein-energy wasting/inflammation or aluminum toxicity, and fewer participants randomly assigned to ferric citrate had serious adverse events. Ferric citrate is an effective phosphate binder with a safety profile comparable to sevelamer and calcium acetate.

The safety and tolerability of ferric citrate as a phosphate binder in dialysis patients

BACKGROUND

A phase II open-label study was conducted in hemodialysis patients evaluating the short-term safety, tolerability, and iron absorption with ferric citrate when used as a phosphate binder.

METHODS

Enrollment occurred in two periods. Period 1 recruited patients taking 6-15 pills/day of binder with phosphorus of ≥2.5 mg/dl. Period 2 recruited patients taking ≥12 pills/day of binder with phosphorus of ≥3.5 mg/dl. Participants with ferritin ≥1,000 µg/l or transferrin iron saturation (TSAT) ≥50% at screening were excluded. Subjects discontinued their previous binders and started 4.5 g/day of ferric citrate (period 1) or 6 g/day (period 2) and were titrated for 4 weeks to maintain a phosphorus of 3.5-5.5 mg/dl. Chemistries and complete blood count were obtained weekly and a gastrointestinal questionnaire was administered at drug initiation and final visit. Iron therapy was permitted if the ferritin was <500 µg/l and TSAT <30%.

RESULTS

Fifty-five subjects were enrolled. Four serious adverse events were reported; none were related to the study drug. Findings from the gastrointestinal questionnaire included stool discoloration (69%), constipation (15%), and bloating (7%). Mean iron parameters at the beginning of the study were ferritin 554 ± 296 µg/l, iron 68 ± 21 µg/dl, and iron saturation 30 ± 7.8%. At the end of study, mean ferritin was 609 ± 340 µg/l (p = 0.02), iron 75 ± 27 µg/dl (p = 0.04), and TSAT was 35 ± 13% (p = 0.001). Mean phosphorus and calcium levels were unchanged from baseline at the end of study.

CONCLUSION

Ferric citrate was well tolerated by patients after 4 weeks with no significant clinical or biochemical adverse events related to exposure.

Decrease in hnRNP A/B expression during erythropoiesis mediates a pre-mRNA splicing switch

A physiologically important alternative pre-mRNA splicing switch, involving activation of protein 4.1R exon 16 (E16) splicing, is required for the establishment of proper mechanical integrity of the erythrocyte membrane during erythropoiesis. Here we identify a conserved exonic splicing silencer element (CE(16)) in E16 that interacts with hnRNP A/B proteins and plays a role in repression of E16 splicing during early erythropoiesis. Experiments with model pre-mRNAs showed that CE(16) can repress splicing of upstream introns, and that mutagenesis or replacement of CE(16) can relieve this inhibition. An affinity selection assay with biotinylated CE(16) RNA demonstrated specific binding of hnRNP A/B proteins. Depletion of hnRNP A/B proteins from nuclear extract significantly increased E16 inclusion, while repletion with recombinant hnRNP A/B restored E16 silencing. Most importantly, differentiating mouse erythroblasts exhibited a stage-specific activation of the E16 splicing switch in concert with a dramatic and specific down-regulation of hnRNP A/B protein expression. These findings demonstrate that natural developmental changes in hnRNP A/B proteins can effect physiologically important switches in pre-mRNA splicing.

Rigid internal fixation for the treatment of infected mandibular fractures

A review of the literature is presented that shows that treatment of infected fractures by rigid internal fixation is biologically sound. A protocol for managing infected mandibular fractures with plate and screw fixation was developed and used on 11 patients. All patients had osseous union of the fracture and none required removal of the bone plate. This protocol is recommended as a viable option in the treatment of infected mandibular fractures.

A somatic gene rearrangement contributing to genetic diversity in maize

We have discovered a somatic genomic rearrangement that occurs at high frequency at a duplicated zein locus in certain cultures of the maize inbred line A188. The rearranged allele arises from the duplication by a two-step process involving a homologous recombination and a second event, which may be a deletion, inversion, or insertion; both steps always occur together. The frequency of rearrangement is lower in homozygous states of the parental allele than in heterozygotes. In both cases, the rearrangement is shown to be mitotic. The rearranged product can be transmitted through meiosis, providing another mechanism for genome evolution in higher eukaryotes.

Isolation of erythropoietin-sensitive cells from Friend virus-infected marrow cultures: characteristics of the erythropoietin response

Murine erythroid precursor cells, stimulated to proliferate in vitro in the absence of added erythropoietin (EP) by the anemia strain of Friend virus (FVA), will subsequently respond to EP by complete erythrocyte differentiation. If not exposed to EP, the erythroid cells divide for about 120 hr in culture, and they maintain the potential for full differentiation in response to EP added at any time during the period from 72 to 120 hr. Between 96 and 120 hr of culture without added EP, the EP-sensitive erythroid precursor cells that have formed discrete erythroid bursts can be isolated in relatively large numbers from such cultures by plucking with a Pasteur pipette. The addition of EP initiates the final stages of erythroid differentiation, including heme synthesis in 70%-80% of these isolated cells. With respect to homogeneity of the precursor cells, quantity of EP-responsive cells obtainable, and uniformity of EP responsiveness, this system is uniquely favorable for biochemical studies of the late differentiation effects of EP. The overall changes in gene expression accompanying EP-induced terminal differentiation were examined by two-dimensional gel electrophoresis of proteins labeled for a short time with radioactive amino acids. Several new proteins are synthesized in these erythroid cells during terminal differentiation, but the number is a very small percentage of the total number of proteins being made. Thus, in this system, the effect of EP is to initiate expression of a small group of genes, including those for globins, spectrin, and other proteins involved in the final stages of erythroid differentiation.

Hemoglobin AIc levels in insulin-dependent and -independent diabetes mellitus

Unusual increases in the minor hemoglobin components (Hb AIa, b, c) known to be elevated in diabetes mellitus were found in states of relative or absolute insulinopenia: diabetic ketoacidosis, steroid-induced diabetes, insulin-dependent diabetes in cystic-fibrosis patients, and cystic fibrosis occurring in infants who have a marked suppression of insulin secretion. In ketoacidotic diabetics, it required at least a month for high Hb AI levels (16.9 +/- 2.6 per cent) to stabilize at nonacidotic levels (12.8 +/- 0.3 per cent), suggesting that decreases occur only as new red cells form under conditions less favorable to Hb AI synthesis. Abnormal amounts os Hb A and Hb AI resisted removal from diabetic red-cell membranes by low ionic buffers but yielded to hypotonic Tris buffer. Their removal resulted in simultaneous elution of peripheral and integral membrane proteins. It is suggested that Hb so firmly bound could reduce membrane elasticity and cell deformability, characteristics so vital to normal red cell movement through the microvasculature.