Development of a Hypoparathyroid Male Rodent Model for Testing Delayed-Clearance PTH Molecules

Context Parathyroid hormone (PTH) replacement is a promising approach in the management of hypoparathyroidism but long-acting analogues need to be developed. To date, animal models for testing PTH required parathyroidectomy by surgery. We have developed a nonsurgical rodent hypoparathyroid model and tested a delayed-clearance PTH molecule (DC-PTH). Objective The aim of this study was to use cinacalcet to suppress calcium levels in normal rats and to reverse these effects with the administration of PTH or PTH analogues Methods Male Wistar rats were gavaged with either 30 mg/kg cinacalcet-HCl (cinacalcet) or vehicle only. Animals were then dosed with either single or repeated subcutaneous doses of PTH 1-34 or a DC-PTH at 20 nmol/kg. Control animals received vehicle only. Serum samples were analyzed for ionized calcium (iCa), phosphate, PTH, and DC-PTH. A pharmacokinetic-pharmacodynamic (PK-PD) model was built for cinacalcet, PTH 1-34, and DC-PTH using Phoenix64. Results Cinacalcet reduced iCa levels between 2 and 24 hours, returning to baseline by 72 hours post dose with nadir at 8 hours (analysis of variance P < .001), associated with a fall in rat PTH. For phosphate there was a variable biphasic response. Single-dose PTH abrogated the cinacalcet-induced fall in iCa for up to 2 hours. DC-PTH prevented the fall in iCa from 4 hours post dose and gave a prolonged response, with iCa levels quicker to return to baseline than controls. DC-PTH has a half-life of 11.5 hours, approximately 44 times longer than human PTH 1-34. The PK-PD models defined the reproducible effect of cinacalcet on iCa and that DC-PTH had prolonged biological activity. Conclusion The administration of cinacalcet provides a robust and reproducible nonsurgical animal model of hypoparathyroidism. DC-PTH holds promise for the treatment of hypoparathyroidism in the future.

Rate of Prolonged Response after Stopping Thrombopoietin-Receptor Agonists Treatment in Primary Immune Thrombocytopenia (ITP): Results from a Nationwide Prospective Multicenter Interventional Study (STOPAGO)

Background: Thrombopoietin receptor agonists(TPO-RAs) have been thought to play only a supporting role in ITP management. Several retrospective studies and a recent prospective study have reported unexpected cases of durable remission after TPO-RAs discontinuation in adult ITP in up to 30%. However, newly diagnosed ITP cases for which spontaneous remission may occur have been included in most of these studies. Thus, the main purpose of this study was to determine the proportion of patients with either persistent or chronic phase and no recent exposure to any potentially curative therapy (i.e., splenectomy or rituximab) achieving long-term remission off-treatment at 24 and 52 months after at least 3 months of TPO-RAs exposure with a complete response (CR). Patients/methods: We conducted a nationwide prospective multicenter interventional study (NCT03119974). Inclusion criteria were: 1) Patients aged > 18 years, with persistent or chronic primary ITP, 2) A stable CR defined by a platelet count > 100 x 10 9/L for more than 2 months on TPO-RA therapy, 3) Treatment with TPO-RA for at least 3 months. Main exclusion criteria were: 1) Anticoagulation or anti-platelet treatment, 2) Previous failure of TPO-RA discontinuation, 3) Concomitant treatment with corticosteroids ± intravenous immunoglobulin 4) Rituximab or splenectomy within the 2 months preceding or after TPO-RA initiation. After inclusion, the decrease and wean of either eltrombopag or romiplostim was initiated according to a standardized protocol (respectively tapering of 25 mg every 2 weeks or tapering of 1 ug/kg every week). In any case TPO-RAs had to be stopped at week 10. In case of relapse after TPO-RA discontinuation, the decision to start a new therapy was left at every investigator discretion. The primary endpoint was the proportion of patients achieving an overall response (CR + R) at week 24 (6 months) after TPO-RAs discontinuation. Secondary outcomes were overall response rate over the study period (W52), bleeding events, and to identify predictive factors, for overall prolonged response (W24 and W52). Results: Forty-nine patients (30 females, 61%), with persistent (n=2) or chronic (n=47, 96%) chronic ITP, with a median age of 58.5 years IQR (41 to 73) fulfilling the eligibility criteria were included over 2 year-period in 22 centers from the French reference network for adult' ITP. Forty patients received eltrombopag and 9 romiplostim at the time of inclusion. One patient was excluded since she was diagnosed pregnant one day after inclusion. In intention to treat 27/48 (56.2%; 95% CI, 29.5 to 58.8) patients achieved the primary-endpoint and maintained an overall response at week 24 after TPO-RAS discontinuation with a complete response for 15/27 (55%). During the full follow-up period of 52 weeks after TPO-RAs discontinuation, overall response was observed in 25/48 (52.1%; 95% CI, 37.2 to 66.2) patients (Figure 1). Bleeding events occurred in 13/21 (61.9%) and 15/23 (65.2%) patients relapsing respectively at 24 and 52 months with a median platelet count of 31´10 9/L(26 to 39) and 31 ´10 9/L(23 to 39). No severe bleeding episode (French bleeding score > 8) occurred. Median time of relapse after tapering initiation was 8 weeks. Among 21 patients with a relapse (<30 x 10 9/L) before week 24, 13 patients were re-challenged with the same TPO-RA with a CR achieved with a median time of 2 weeks (2-4). In univariate analysis, age, ITP duration, TPO-RA duration before discontinuation, platelet count at inclusion and TPO-RAs drug class were not predictive of sustained response. Conclusion: These results showed an unexpectedly high rate of sustained off-treatment remission after TPO-RAs discontinuation in chronic ITP among patients who initially achieve a stable CR. When they occur, relapses are mainly observed within the first weeks after discontinuation, very rarely afterwards and with no severe bleeding. While no predictive factor of lasting remission has been yet identified, our study strongly supports a progressive tapering of the dose of TPO-RAs in patients achieving a stable CR on treatment. Figure 1: Relapse at 52 weeks after TPO-RAs discontinuation Figure 1 Figure 1. Disclosures Mahevas: GSK: Research Funding; Amgen: Honoraria. Viallard: Novartis: Consultancy; Grifols: Consultancy; LFB: Consultancy; Amgen: Consultancy. Moulis: Amgen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Argenx: Membership on an entity's Board of Directors or advisory committees; Grifols: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; Sobi: Membership on an entity's Board of Directors or advisory committees. Terriou: Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Michel: Novartis: Consultancy; Amgen: Consultancy; UCB: Honoraria; Argenx: Honoraria; Rigel: Honoraria; Alexion: Honoraria. Godeau: Sobi: Consultancy; Novartis: Consultancy; Amgen: Consultancy; Grifols: Consultancy.

Long Term Immune Response Produced by the SputnikV Vaccine

SputnikV is a vaccine against SARS-CoV-2 developed by the Gamaleya National Research Centre for Epidemiology and Microbiology. The vaccine has been shown to induce both humoral and cellular immune responses, yet the mechanisms remain largely unknown. Forty SputnikV vaccinated individuals were included in this study which aimed to demonstrate the location of immunogenic domains of the SARS-CoV-2 S protein using an overlapping peptide library. Additionally, cytokines in the serum of vaccinated and convalescent COVID-19 patients were analyzed. We have found antibodies from both vaccinated and convalescent sera bind to immunogenic regions located in multiple domains of SARS-CoV-2 S protein, including Receptor Binding Domain (RBD), N-terminal Domain (NTD), Fusion Protein (FP) and Heptad Repeats (HRs). Interestingly, many peptides were recognized by immunized and convalescent serum antibodies and correspond to conserved regions in circulating variants of SARS-CoV-2. This breadth of reactivity was still evident 90 days after the first dose of the vaccine, showing that the vaccine has induced a prolonged response. As evidenced by the activation of T cells, cellular immunity strongly suggests the high potency of the SputnikV vaccine against SARS-CoV-2 infection.

A Patient with Metastatic Microsatellite Instability-High Pancreatic Ductal Adenocarcinoma with a Prolonged Response to Single-Agent Pembrolizumab

Immunotherapy is an effective new approach in the treatment of many malignancies. However, pancreatic ductal adenocarcinoma (PDAC) does not usually respond to immunotherapy. We discuss the case of a patient with metastatic microsatellite instability-high PDAC who had a prolonged response to single-agent pembrolizumab for almost 3 years.