Disease Analysis: Anemia in Chronic Kidney Disease
|出版日||ページ情報||英文 84 Pages
|疾患分析：慢性腎臓病における貧血 Disease Analysis: Anemia in Chronic Kidney Disease|
|出版日: 2020年04月21日||ページ情報: 英文 84 Pages||
慢性腎疾患（CKD）市場における貧血は、高いヘモグロビン値 (Hb値) を目標とする際の心血管イベントのリスクが増加したことから、Hbの目標値が下がり、薬剤の投与を決定する際の警戒感が高くなったため、特に米国において、ベストセラーかつ標準治療となっている赤血球生成刺激剤 (ESA製剤) の使用が減少し、苦戦しています。またバイオシミラーは、バイオシミラーの短時間作用型ESAが使用の大部分を占める欧州を中心に、打撃を与えています。米国で最初のバイオシミラーであるRetacritは、2018年に承認されたため、現在も増加しています。ロキサダスタットは、既に日本と中国では承認されていますが、2020年後半に重要な米国市場での最初の承認に向けかって進んでおり、ESAは経口および潜在的に安全なHIF-PH阻害剤によって最終的に置き換えられる可能性があり、さらに相当なシェアを失う可能性があります。しかし、FDAのレビューから詳細を確認することが重要です。 HIF-PH阻害剤は、透析患者に必要なIV鉄の投与量を減らし、その他の利点もあるようです。
The anemia in chronic kidney disease (CKD) market has struggled as usage of high-selling, standard-of-care, injectable erythropoiesis-stimulating agents (ESAs) has declined, especially in the US, due to an increased risk of cardiovascular events when targeting higher Hb levels, which has led to lower Hb targets and more caution when deciding to initiate the drugs. Biosimilars have also taken their toll, particularly in Europe, where biosimilar short-acting ESAs have taken a majority share of usage. The first biosimilar in the US, Retacrit, was only approved in 2018, so is still ramping. The ESAs are poised to lose substantial further share and possibly be eventually displaced by the oral and potentially safer HIF-PH inhibitors, with roxadustat on track for initial approval in the important US market in late 2020, having already been approved in Japan and China. It will be important to see, though, more details from its FDA review. The HIF-PH inhibitors also reduce the dose of IV iron needed in dialysis patients, and appear to have other advantages as well.
Despite dose reductions, ESAs are still currently the mainstay of anemia treatment in dialysis, used in at least 80% of patients in major markets, but in non-dialysis CKD anemia, ESAs are less commonly used, due to the need for injection, safety issues, broader spectrum of anemia severity, and cost. The first-on-the-market shorter-acting intravenous ESAs are more suited for dialysis than other settings, given with three-times weekly (TIW) dosing. Longer-acting products can be given intravenously or, as more convenient for non-dialysis patients, subcutaneously. In dialysis, the decision on which ESAs to use can vary greatly by country, impacted by cost, contractual arrangements (eg with dialysis providers Fresenius and DaVita in the US, which control a majority of the market), preferences for dosing frequencies, and practical issues at dialysis centers.
In the US, the first ESA to be approved, Amgen's short-acting Epogen, is still the largest-selling branded product, as it has retained substantial share in the dialysis market. Outside the US, Amgen's longer-acting Aranesp leads, though a portion of its sales are in oncology indications. Biosimilars to Aranesp have been approved in Japan, where it was favored over shorter-acting agents. Mircera, which is even longer acting, has continued to grow, especially in the US, where its launch was delayed until 2015, with sales driven by Vifor's arrangement with Fresenius and expansion to mid-sized and independent dialysis clinics, though overall ESA sales have continued to decline.
Iron is the other major anemia treatment, used for patients with iron deficiency from a potential multitude of causes associated with CKD. IV irons are particularly important in the dialysis segment, as ESAs increase iron requirements for red blood cell production and IV iron can readily be given in conjunction with dialysis. In non-dialysis patients, oral iron is more convenient, though many patients have gastrointestinal side-effects that can impact compliance.
Non-dextran IV irons are thought to have a lower rate of severe acute adverse events, and Vifor's Venofer, sold by Daiichi in the US, took the lead early on. Venofer has since lost share in the overall IV iron segment to newer options that allowed higher dosing with fewer administrations, especially Vifor's own Injectafer, which now leads the overall IV iron segment in sales, though the growth of these has mainly been in non-dialysis patients and non-CKD indications, where the dosing advantage is more important and outweighs Injectafer's higher price - it is also not specifically labeled for dialysis patients in the US. As a result, Venofer still leads in nephrology sales, due to its use in the US dialysis market. Outside the US, including Europe, iron sucrose similars have surpassed Venofer in gross sales, despite efforts to show they do not have the same efficacy and safety, but sales for both are modest. Outcomes studies of Injectafer and Pharmacosmos's Monoferric in the related comorbidity of heart failure are expected in 2021, and if positive, could expand usage in CKD patients with heart failure. Monoferric can be given in a single dose and was just approved in the US in 2020, with a non-dialysis indication, though sales in Europe have been moderate and a patent infringement lawsuit seeking to keep it off the market was filed in February
The HIF-PH inhibitors have the advantages of oral administration, potentially improved safety (as they more physiologically impact erythropoietin than ESAs), improved iron utilization, and possibly efficacy in certain patients that can be more difficult to treat with ESAs. Hence, they could take substantial share and possibly eventually displace the ESAs, as well as grow anemia treatment in non-dialysis CKD. They are likely to also reduce IV iron use in dialysis patients. More details from the pivotal programs are needed first, though. Roxadustat appears to be at least as effective as ESAs, and the others have some evidence suggesting that as well, especially since efficacy can be a matter of dose titration, though data from the global Phase III studies of these other candidates are pending for later this year.
Only roxadustat has CV safety data so far, and while there are signs of a potential CV advantage, the picture may not be as clear as one might have hoped for, though that may just be an indication that ESAs are not as dangerous at the lower Hb targets used. In dialysis patients, there was a benefit on MACE+ versus epoetin alfa, the European endpoint, which is encouraging. Part of the benefit, though, was due to heart failure, rather than more typical atherosclerotic endpoints, and more data are needed to see if that was related to lower hypertension, as well as whether there were any differences in various thrombotic events. There was a substantial reduction in events in the incident dialysis subgroup, but details have not been released on the chronic dialysis subgroup. Some controversies over the data have been raised, but more details will likely come out at an FDA advisory committee meeting. In non-dialysis patients, it was positive that roxadustat demonstrated non-inferiority to placebo on CV outcomes. Rates of MACE and MACE+ were slightly numerically higher than placebo, with a somewhat larger numerical increase in the individual endpoint of stroke, though these could all be due to chance. It was somewhat curious, though, that the pattern of slightly higher MACE and a more pronounced increase in stroke was similar to what was seen in Aranesp's large TREAT study, which contributed to concern over ESAs, though the increase in stroke with Aranesp was substantially higher and statistically significant.
Roxadustat is also being dosed TIW, which may be more difficult for non-dialysis patients to remember, opening the door to competitors vadadustat and daprodustat, which have daily dosing, though there may be ways around the issue. Global Phase III details for vadadustat and daprodustat are expected this year, which will help to better define their product profiles, as well as how the class is viewed compared to ESAs, particularly in terms of CV side-effects. However, the major non-dialysis studies for vadadustat and daprodustat with CV outcomes have ESA comparators rather than placebo, and if there is not much difference, they will not have the comparison against placebo in their favor. Nevertheless, their hope is that demonstrating benefits on other secondary outcomes will contribute to a commercial advantage, even if the drugs are shown to be no worse on CV outcomes than ESAs.
At least the initial HIF-PH inhibitors should receive an extra payment for two years under Medicare's TDAPA, though it is not clear if MedPAC recommendations may impact that.
The overall likelihood of approval for Phase I assets is 23% for anemia in dialysis-dependent CKD and 38.1% for anemia in dialysis-independent CKD, with the average probabilities that a drug advances from Phase III at 87.5% and 85.7%, respectively. It takes on average 9.7-9.8 years for drugs in these indications to move from Phase I to approval, compared to 9.1 years in the overall hematology space.