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公平地取得長效型 PrEP正在路途當中嗎?

公平地取得長效型 PrEP正在路途當中嗎?

資料來源: www.thelancet.com/hiv / 2022 年 6 月 9 日;財團法人台灣紅絲帶基金會編譯

    5 月,ViiV Healthcare 宣布正在與藥品專利池(MPP)就可注射型長效 cabotegravir(CAB-LA)作為暴露前預防(PrEP)的自願許可進行談判。這一發展可能允許在低收入和中等收入國家( LMIC )中生產 CAB-LA 的學名藥,類似於該公司與藥品專利池(MPP)就dolutegravir學名藥的現有合作夥伴關係。如果要實現聯合國愛滋病規劃署 2030 年的目標,公平獲得另一種 PrEP 之選擇是重要的一步。

    自 2021 年 12 月 CAB-LA 作為 PrEP 獲得美國批准以來,已在澳大利亞、波札那、巴西、肯亞、馬拉威、南非、烏干達和辛巴威提交了許可申請。然而,每劑 3,700 美元(每年約 22, 000 美元)的初始定價,使其每年的成本與美國的品牌口服 PrEP(學名為富馬酸替諾福韋酯和恩曲他濱,商品名舒發泰)大致相同(每年約 21,600 美元),顯然會使中低收入國家的大多數人無法獲得藥物。自從在美國引入學名藥後,口服 PrEP 的成本直線下降,現在每年不到 1,200 美元。 Clinton Health Access Initiative 的一項分析顯示,在撒哈拉以南非洲大規模生產 CAB-LA學名藥是可行的,估計每人每年的成本為 16-23 美元。這些成本是使用該地區成功擴大注射和植入型避孕藥的規模作為比較來計算的,目前估計使用人數為每年 3,600 萬人。

    到 2020 年,中低收入國家中口服 PrEP 的估計使用量僅為聯合國愛滋病規劃署 300 萬人目標的 28%。在撒哈拉以南非洲地區,口服 PrEP 繼續大規模推廣,覆蓋面參差不齊,肯亞和南非的使用率最高。來自該地區 PrEP 實施和示範研究的數據顯示,在一些 HIV 高危人群中,特別是在青春期女孩和年輕女性中,PrEP 的停藥率高得令人擔憂。 2020 年,撒哈拉以南非洲 25% 的新愛滋病毒感染者是少女和年輕女性,她們僅佔人口的 10%。順從性和污名已被確定為透過口服 PrEP 以成功地預防 HIV 的重要障礙。獲得長效可注射型 PrEP 可能會克服一些人在口服製劑方面面臨的挑戰。長效注射型 PrEP 將提供一種謹慎替代口服 PrEP的方法,需要每 2 個月就診一次,並且可以消除在服用錠劑形式的抗反轉錄病毒藥物時相關的污名。事實上,當使用離散選擇方法進行調查時,年輕的南非女性表示,與最不受歡迎的每日口服 PrEP 相比,每 2-3 個月注射一次 PrEP 將是最優選的方式。

    HPTN 083 和 HPTN 084 試驗均顯示,在男男性行為者、跨性別女性和順性別女性中,CAB-LA 與口服 PrEP 一樣安全有效,並且正在對青少年和孕婦進行研究。然而,關於使用 CAB-LA 的真實數據很少。例如,需要有關孕婦和哺乳期婦女安全性和有效性的數據,因為在這一群體中感染愛滋病毒的風險可能會增加一倍以上。CAB-LA更容易遵守可以使其在懷孕期間和產後成為一個不錯的選擇。需要更多數據來說明在按照處方使用 CAB-LA 時感染 HIV 的人群中整合酶抑製劑耐藥性的風險,以及其在藥物代謝動力學上長的尾部是否會產生實質性影響。對 HPTN 083 試驗數據的分析顯示,當參與者確實出現抗藥性時,並不是在尾期。

    現在即開始計畫 CAB-LA 的推廣至關重要,從口頭 PrEP 的教訓中學習也是如此。與口服 PrEP 相比,注射劑型的製造需要更複雜的技術。交付策略應考慮目標人群的情況和便利之需求。例如,設想肌內注射可以與避孕注射同時容易地給藥。還應考慮該地區衛生保健專業人員的培訓和資源需求。

    不能允許讓成本破壞新型式的 PrEP 模式之擴大。 在中低收入國家,特別是在撒哈拉以南非洲,提供 CAB-LA 將增加生物醫學預防設備,包括口服 PrEP 和 dapivirine 陰道環,以及其他預防選擇,例如避孕套和自願性男性包皮環切術醫療。 應盡快完成關於許可條款、必要的技術轉讓和臨時定價的協議,以便讓 CAB-LA 成為最需要的人的選擇。 公平地獲得 PrEP 的多種選擇對於阻止 HIV 傳播至關重要。 ■ 刺胳針愛滋病毒 

            Equitable access to long-acting PrEP on the way?

    In May, ViiV Healthcare announced that it was negotiating with the Medicines Patent Pool (MPP) for the voluntary licencing of injectable long-acting cabotegravir (CAB-LA) as pre-exposure prophylaxis (PrEP). This development will potentially allow manufacture of generic versions of CAB-LA in low-income and middle-income countries (LMICs), similar to the company’s existing partnership with the MPP for generic dolutegravir. Equitable access to another option for PrEP is an important step if UNAIDS 2030 targets are to be met. 

    Since CAB-LA received US approval as PrEP in December, 2021, licensing applications have been filed in Australia, Botswana, Brazil, Kenya, Malawi, South Africa, Uganda, and Zimbabwe. However, initial pricing of US$3700 per dose (about $22 000 per year), putting its yearly cost at about the same as branded oral PrEP (tenofovir disoproxil fumarate and emtricitabine) in the USA (about $21600 per year), would clearly make the drug inaccessible to most people in LMICs. Since the introduction of generic forms in the USA, the cost of oral PrEP has plummeted and it is now available for less than $1200 per year. An analysis by the Clinton Health Access Initiative suggests that the manufacture of generic CAB-LA at scale in sub-Saharan Africa would be feasible, with estimated costs of $16–23 per person per year. These costs were calculated using the successful scale-up of injectable and implantable contraception in the region as a comparator, for which the estimated number of users is now 36 million people per year. 

    The estimated use of oral PrEP in LMICs in 2020 was only 28% of the UNAIDs target of 3 million people. In subSaharan Africa, where oral PrEP continues to roll out at scale, coverage is patchy, with uptake greatest in Kenya and South Africa. Data from PrEP implementation and demonstration studies in the region show worryingly high PrEP discontinuation rates in some populations at high risk of HIV, in particular among adolescent girls and young women. In 2020, 25% of new HIV infections in subSaharan Africa were in adolescent girls and young women, who comprise only 10% of the population. Adherence and stigma have been identified as important barriers to successful HIV prevention with oral PrEP. Having access to long-acting injectable PrEP might overcome the challenges some people face with oral formulations. Long-acting injectable PrEP would provide a discreet alternative to oral PrEP requiring visits to the clinic only every 2 months, and could remove stigma associated with taking antiretrovirals in tablet form. Indeed, when surveyed with discrete choice methods, young South African women have indicated that injectable PrEP every 2–3 months would be the most preferred modality compared with daily oral PrEP, which was least preferred. 

    Both the HPTN 083 and HPTN 084 trials showed CAB-LA is as safe and effective as oral PrEP among cisgender men who have sex with men, transgender women, and cisgender women, and studies are underway in adolescents and pregnant women. However, real-world data on the use of CAB-LA are scarce. For example, data on safety and effectiveness in pregnant and breastfeeding women are needed since the risk of acquiring HIV can more than double in this group. Easier adherence to CAB-LA could make it a good option during pregnancy and in the post-partum period. More data are needed on the risk of integrase inhibitor resistance in people who acquire HIV while taking CAB-LA as prescribed, and whether its long pharmacokinetic tail will have a substantial effect. Analysis of the HPTN 083 trial data showed that when resistance did emerge in participants, it was not during the tail phase.

    Planning now for CAB-LA roll-out is essential, as is learning from the lessons of oral PrEP. Manufacture of injectables will require more complex technologies than those needed for oral PrEP. Delivery strategies should consider the circumstances and convenience needs of the targeted population. For example, it is envisaged that the intramuscular injections could be easily administered at the same time as contraceptive injections. The training and resource needs of health-care professionals in the region should also be considered. 

    Cost cannot be allowed to derail the scale up of new PrEP modalities. The provision of CAB-LA in LMICs, particularly in sub-Saharan Africa, will add to the biomedical prevention armamentarium that includes oral PrEP and the dapivirine vaginal ring but also other prevention options, such as condoms and voluntary medical male circumcision. Agreement on the terms of licensing, necessary transfers of technology, and interim pricing should be completed urgently so that CAB-LA becomes an option for those most in need. Equitable access to multiple options for PrEP is essential to stop HIV transmission. ■ The Lancet HIV

 

 

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