Cinacalcet HCl: a novel therapeutic for hyperparathyroidism

Recommendations of the Spanish Society of Nephrology for the management of mineral and bone metabolism disorders in patients with chronic kidney disease: 2021 (SEN-MM)

As in 2011, when the Spanish Society of Nephrology (SEN) published the Spanish adaptation to the Kidney Disease: Improving Global Outcomes (KDIGO) universal Guideline on Chronic Kidney Disease-Mineral and Bone Disorder (CKD-MBD), this document contains an update and an adaptation of the 2017 KDIGO guidelines to our setting. In this field, as in many other areas of nephrology, it has been impossible to irrefutably answer many questions, which remain pending. However, there is no doubt that the close relationship between the CKD-MBD/cardiovascular disease/morbidity and mortality complex and new randomised clinical trials in some areas and the development of new drugs have yielded significant advances in this field and created the need for this update. We would therefore highlight the slight divergences that we propose in the ideal objectives for biochemical abnormalities in the CKD-MBD complex compared to the KDIGO suggestions (for example, in relation to parathyroid hormone or phosphate), the role of native vitamin D and analogues in the control of secondary hyperparathyroidism and the contribution of new phosphate binders and calcimimetics. Attention should also be drawn to the adoption of important new developments in the diagnosis of bone abnormalities in patients with kidney disease and to the need to be more proactive in treating them. In any event, the current speed at which innovations are taking place, while perhaps slower than we might like, globally drives the need for more frequent updates (for example, through Nefrología al día).

How Do Modulators Affect the Orthosteric and Allosteric Binding Pockets?

Allosteric modulators (AMs) that bind allosteric sites can exhibit greater selectivity than the orthosteric ligands and can either enhance agonist-induced receptor activity (termed positive allosteric modulator or PAM), inhibit agonist-induced activity (negative AM or NAM), or have no effect on activity (silent AM or SAM). Until now, it is not clear what the exact effects of AMs are on the orthosteric active site or the allosteric binding pocket(s). In the present work, we collected both the three-dimensional (3D) structures of receptor-orthosteric ligand and receptor-orthosteric ligand-AM complexes of a specific target protein. Using our novel algorithm toolset, molecular complex characterizing system (MCCS), we were able to quantify the key residues in both the orthosteric and allosteric binding sites along with potential changes of the binding pockets. After analyzing 21 pairs of 3D crystal or cryo-electron microscopy (cryo-EM) complexes, including 4 pairs of GPCRs, 5 pairs of ion channels, 11 pairs of enzymes, and 1 pair of transcription factors, we found that the binding of AMs had little impact on both the orthosteric and allosteric binding pockets. In return, given the accurately predicted allosteric binding pocket(s) of a drug target of medicinal interest, we can confidently conduct the virtual screening or lead optimization without concern that the huge conformational change of the pocket could lead to the low accuracy of virtual screening.

Cinacalcet Targets the Neurokinin-1 Receptor and Inhibits PKCδ/ERK/P65 Signaling to Alleviate Dextran Sulfate Sodium-Induced Colitis

Objective: Inflammatory bowel disease is an immune-mediated chronic inflammatory disease of the gastrointestinal tract for which curative drugs are currently not available. This study was performed to assess the therapeutic effects of cinacalcet on dextran sulfate sodium (DSS)-induced colitis. Methods: Primary macrophages obtained from bone marrow and the macrophage cell line RAW264.7 were used to examine the inhibitory effect of cinacalcet on cytokine production, the PKCδ/ERK/P65 signaling pathway, and NF-κB P65 translocation. Colitis was induced using DSS to assess the treatment effect of cinacalcet. Bioinformatics approaches were adopted to predict potential targets of cinacalcet, and a drug affinity responsive target stability (DARTs) assay was performed to confirm binding between cinacalcet and potential target. Results: In vivo analysis showed that cinacalcet reduced the disease activity score, prevented shortening of the colon, diminished inflammatory cell infiltration, and protected the structural integrity of the intestinal wall. Cinacalcet also reduced production of the inflammatory cytokines TNFα, IL-1β, and IL-6 in the colon and sera of mice with DSS-induced colitis. In vitro studies revealed that cinacalcet suppressed the translocation of P65 and inhibited production of the inflammatory cytokines IL-1β and IL-6. Mechanistic studies revealed that the target of cinacalcet was neurokinin-1 receptor (NK1R) and their binding was confirmed by a DARTs assay. Furthermore, the inhibition of NK-κB P65 activation was found to occur via the suppression of PKCδ/ERK/P65 signaling mediated by cinacalcet. Conclusion: Cinacalcet inhibits the activation of NF-κB and reduces the production of inflammatory cytokines by suppressing the PKCδ/ERK/P65 signaling pathway via targeting NK1R, suggesting that it can be used to treat inflammatory diseases, particularly colitis.

Quality by Design Enabled Development of Oral Self-Nanoemulsifying Drug Delivery System of a Novel Calcimimetic Cinacalcet HCl Using a Porous Carrier: In Vitro and In Vivo Characterisation

In this present research, work quality by design-enabled development of cinacalcet HCl (CH)-loaded solid self-nanoemulsifying drug delivery system (S-SNEDDS) was conducted using a porous carrier in order to achieve immediate drug release and better oral bioavailability. Capmul MCM (CAP), Tween 20 (TW 20) and Transcutol P (TRP) were selected as excipients. Cumulative % drug release at 30 min (Q30), emulsification times (ET), mean globule size (GS) and polydispersity index (PDI) were identified as critical quality attributes (CQAs). Factor mode effect analysis (FMEA) and Taguchi screening design were applied for screening of factors. The optimised single dose of S-SNEDDS obtained using Box-Behnken design (BBD) consisted of 30 mg of CH, 50 mg of CAP, 149.75 mg of TW 20, 55 mg of TRP and 260.75 mg of Neusilin US2. It showed an average Q30 of 97.6%, ET of 23.3 min, GS of 89.5 nm and PDI of 0.211. DSC, XRD and SEM predict the amorphous form of S-SNEDDS. In vivo pharmacokinetic study revealed better pharmacokinetic parameters of S-SNEDDS. The above study concluded that the optimised S-SNEDDS is effective to achieve the desired objective. Graphical Abstract.

Performance of new 400-MHz HTS power-driven magnet NMR technology on typical pharmaceutical API, cinacalcet HCl

After years towards higher field strength magnets, nuclear magnetic resonance (NMR) technology in commercial instruments in the past decade has expanded at low and high magnetic fields to take advantage of new opportunities. At lower field strengths, permanent magnets are well established, whereas for midrange and high field, developments utilize superconducting magnets cooled with cryogenic liquids. Recently, the desire to locate NMR spectrometers in nontypical NMR laboratories has created interest in the development of cryogen-free magnets. These magnets require no cryogenic maintenance, eliminating routine filling and large cryogen dewars in the facility. Risks of spontaneous quenches and safety concerns when working with cryogenic liquids are eliminated. The highest field commercially available cryogen-free NMR magnet previously reported was at 4.7 T in 2013. Here we tested a prototype cryogen-free 9.4-T power-driven high-temperature-superconducting (HTS) magnet mated to commercial NMR spectrometer electronics. We chose cinacalcet HCl, a typical active pharmaceutical ingredient, to evaluate its performance towards structure elucidation. Satisfactory standard 1D and 2D homonuclear and heteronuclear NMR results were obtained and compared with those from a standard 9.4-T cryogenically cooled superconducting NMR instrument. The results were similar between both systems with minor differences. Further comparison with different shims and probes in the HTS magnet system confirmed that the magnet homogeneity profile could be matched with commercially available NMR equipment for optimal results. We conclude that HTS magnet technology works well providing results comparable with those of standard instruments, leading us to investigate additional applications for this magnet technology outside a traditional NMR facility.

The effect of cinacalcet on intraoperative findings in tertiary hyperparathyroidism patients undergoing parathyroidectomy

INTRODUCTION

Tertiary hyperparathyroidism (3HPTH) patients who undergo parathyroidectomy (PTX) are often managed with calcium lowering medications such as cinacalcet (Sensipar) before surgery. Here, we assess how cinacalcet treatment influences intraoperative parathyroid hormone (IOPTH) kinetics and surgical findings in 3HPTH patients undergoing PTX.

METHODS

We reviewed retrospectively 113 patients 3HPTH who underwent PTX, 14 of whom were taking cinacalcet and 112 who were not taking the drug. IOPTH levels fitted to linear curves versus time were used to evaluate the role of cinacalcet.

RESULTS

Cinacalcet did not correlate with rates of cure (P = .41) or recurrence (P = .54). Patients taking cinacalcet experienced a steeper decrease in IOPTH compared with those not taking the medication (P = .005). Cinacalcet treatment was associated with an increase in rate of hungry bones (P = .04). Weights of the heaviest glands resected (P = .02) and preoperative PTH levels (P = .0004) were greater among patients taking cinacalcet.

CONCLUSION

Perioperative cinacalcet treatment in patients with 3HPTH alters IOPTH kinetics by causing a steeper decrease in IOPTH, but does not require modification of the standard IOPTH protocol. Although cinacalcet use does not adversely affect cure rates, it is associated with greater preoperative PTH and an increased incidence of hungry bones, hence serving as an indicator of more severe disease. Cinacalcet does not need to be held before operation.

Hyperfunctional parathyroid carcinoma with mediastinal extension

Parathyroid carcinoma (PC) is an extremely rare malignancy, 0.005% of all tumours and between 0.5% and 5% of all parathyroid neoplasms. Preoperative diagnosis is often difficult and is almost always obtained only after post-surgical histopathology. The prognosis is related to the local extent of disease and to complete surgical resection of the tumour. We report an uncommon case of hyperfunctional PC with mediastinal extension, emphasising the diagnostic difficulties, histopathological features and treatment strategies. The most recent data in the literature is analysed as well.

Antagonists of the calcium receptor. 2. Amino alcohol-based parathyroid hormone secretagogues

When administered as a single agent to rats, the previously reported calcium receptor antagonist 3 elicited a sustained elevation of plasma PTH resulting in no increase in overall bone mineral density. The lack of a bone building effect for analogue 3 was attributed to the large volume of distribution (V(dss)(rat) = 11 L/kg), producing a protracted plasma PTH profile. Incorporation of a carboxylic acid functionality into the amino alcohol template led to the identification of 12 with a lower volume of distribution (V(dss)(12) = 1.18 L/kg) and a shorter half-life. The zwitterionic nature of antagonist 12 necessitated the utility of an ester prodrug approach to increase overall permeability. Antagonist 12 elicited a rapid and transient increase in circulating levels of PTH following oral dosing of the ester prodrug 11 in the dog. The magnitude and duration of the increases in plasma levels of PTH would be expected to stimulate new bone formation.

Cinacalcet reduces the set point of the PTH-calcium curve

The calcimimetic cinacalcet increases the sensitivity of the parathyroid calcium-sensing receptor to calcium and therefore should produce a decrease in the set point of the parathyroid hormone (PTH)-calcium curve. For investigation of this hypothesis, nine long-term hemodialysis patients with secondary hyperparathyroidism were given cinacalcet for 2 mo, the dosage was titrated per a protocol based on intact PTH and plasma calcium concentrations. Dialysis against low- and high-calcium (0.75 and 1.75 mM) dialysate was used to generate curves describing the relationship between PTH and calcium. Compared with precinacalcet levels, cinacalcet significantly reduced mean serum calcium, intact PTH and whole PTH (wPTH; all P < 0.001). The set points for PTH-calcium curves were significantly reduced, and both maximum and minimum levels of PTH (intact and whole) were significantly decreased. The calcium-mediated inhibition of PTH secretion was more marked after cinacalcet treatment. In addition, cinacalcet shifted the inverse sigmoidal curve of wPTH/non-wPTH ratio versus calcium to the left (i.e., less calcium was required to reduce the wPTH/non-wPTH ratio). In conclusion, cinacalcet increases the sensitivity of the parathyroids to calcium, causing a marked reduction in the set point of the PTH-calcium curve, in hemodialysis patients with secondary hyperparathyroidism.

Does vitamin D receptor and calcium receptor activation therapy play a role in the histopathologic alterations of parathyroid glands in refractory uremic hyperparathyroidism?

BACKGROUND AND OBJECTIVES

Vitamin D receptor activation by vitamin D sterols and calcium-sensing receptor stimulation by cinacalcet are the most powerful treatments of secondary hyperparathyroidism. This study was aimed to assess a possible association between histopathologic changes of parathyroid tissue and treatment modality.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Studies were performed on 82 parathyroids of 22 adult white hemodialysis patients undergoing first parathyroidectomy. The type of hyperplasia and the distribution of chief and oxyphil cells, expressed as oxyphil/chief cell ratio, were assessed. Three groups could be studied according to treatment modality: group A consisted of 6 patients who were treated with cinacalcet, intravenous calcitriol, and phosphate binders; group B consisted of 6 patients who were treated with intravenous calcitriol and phosphate binders, and group C consisted of 10 patients who were treated with phosphate binders alone.

RESULTS

Sixty-eight (82.9%) out of 82 glands removed showed nodular hyperplasia. It was more frequent in groups A and B than in group C. A stepwise forward logistic regression model showed that the probability of nodular hyperplasia was higher in patients who were on calcitriol and/or cinacalcet therapy, in female gender and in patients with a higher body mass index. Oxyphil/chief cell ratio also was significantly different among the three groups. Cinacalcet treatment was the only predictor of this ratio.

CONCLUSIONS

An association was found between calcitriol and/or cinacalcet therapy and a high prevalence of nodular hyperplasia, and between cinacalcet therapy and high oxyphil/chief cell ratio. The meaning of the observed associations remains uncertain.

Medical therapy of secondary hyperparathyroidism in chronic kidney disease: old and new drugs

Secondary hyperparathyroidism (SHPT), a common complication of chronic kidney disease, is characterised by elevated serum levels of parathyroid hormone, parathyroid hyperplasia, excessive bone resorption and increased risk for cardiovascular morbidity. The stringent metabolic targets proposed by the National Kidney Foundation Kidney Disease Outcomes Quality Initiative (K/DOQI) for patients with SHPT are difficult to achieve using conventional treatment regimens. Several new agents, including new vitamin D sterols and phosphate binders, as well as a novel class of compounds--the calcimimetics--have been developed in recent years. This review examines new and traditional therapies for SHPT and how these can best be utilised in order to achieve the new K/DOQI targets.