Advances in Synergistic Antitumor Effects of Radiopharmaceuticals Combined with Immune Checkpoint Inhibitors
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摘要: 靶向放射性核素治疗诱导DNA双链断裂,激活cGAS-STING通路、NF-κB/IRF3通路和STAT1/3-IRF1通路,上调程序性死亡受体配体1(programmed death-ligand 1,PD-L1)的表达,促炎细胞因子、CD8+ T细胞及CD4+ T细胞在肿瘤中浸润增加,为免疫检查点抑制剂治疗提供了有利的免疫原性微环境。联合治疗使得正向调节免疫反应的记忆效应T细胞、M1型巨噬细胞及树突状细胞浸润增加,免疫抑制性的调节性T细胞、M2型巨噬细胞及髓源性抑制细胞下调,部分小鼠肿瘤完全缓解并产生免疫记忆。值得注意的是,放射性诊断药物2-[18F]FDG联合PD-L1抗体治疗也可调控免疫微环境,显著提高疗效。本文主要综述目前典型的放射性药物联合免疫检查点抑制剂协同抗肿瘤治疗策略,并强调联合治疗时间窗以及不同的治疗组合可能改善治疗效果,提出诊断放射性药物联合免疫治疗有望成为一种新的肿瘤治疗范式,或将成为未来研究的重要方向。
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关键词:
- 2-[18F]FDG /
- 靶向放射性核素治疗 /
- PD-L1抗体 /
- 肿瘤免疫微环境
Abstract: Targeted radionuclide therapy (TRT) provides an immunogenic microenvironment for immune checkpoint inhibitor (ICI) therapy by inducing DNA double-strand break, activating the cGAS-STING, NF-κB/IRF3 and STAT1/3-IRF1 pathways, up-regulating the expression of PD-L1, and increasing the infiltration of pro-inflammatory cytokines, CD8+ T cells and CD4+ T cells in tumors. The combined therapy could increase the infiltration of memory effector T cells, M1 macrophages and dendritic cells which positively regulate immune response, and downregulate immunosuppressive regulatory T cells, M2 macrophages and myeloid-derived suppressor cells. Partial complete remission and immune memory were achieved in tumor-bearing mice treated with combined therapy. It is worth noting that radiodiagnostic agent 2-[18F]FDG combined with anti-PD-L1 mAb could also reprogram the immune microenvironment and significantly improve therapeutic effect. This review presents typical combination therapy strategies, emphasizes the time window of combination therapy and different combinations of therapy that may improve the therapeutic effect, and proposes that radiodiagnostic agents combined with tumor immunotherapy are expected to become a new paradigm and a direction for further research in the future. -
近10年来,免疫检查点抑制剂(immune checkpoint inhibitor,ICI)在肿瘤治疗领域取得了重大突破。2011年,第一个靶向细胞毒性T淋巴细胞抗原4(cytotoxic T-lymphocyte antigen 4, CTLA-4)的ICI伊匹单抗(Ipilimumab)获得美国食品药品监督管理局(Food and Drug Administration,FDA)批准用于晚期黑色素瘤的治疗,此后多个靶向程序性死亡受体1及其配体(programmed death-1/ligand 1, PD-1/ PD-L1)及淋巴细胞激活基因-3(lymphocyte activation gene-3, LAG-3) 的ICI陆续上市[1-2]。虽然ICI在多种转移性、难治性恶性肿瘤中获得了持久反应性,但患者对于ICI单药的响应率仅为20%~40%[3-4]。而ICI治疗产生的免疫相关不良事件及获得性耐药均可导致疾病进展[4],因此,与其他治疗方式联合成为ICI治疗的新方向[2]。
研究表明,外照射放疗(external beam radiation therapy, EBRT)可引起肿瘤细胞DNA损伤、信号转导调节以及肿瘤免疫微环境(tumor immune microenvironment, TIME)重塑[5]。EBRT通过均匀的低传能线密度(linear energy transfer, LET)射线,包括X射线及γ射线(0.2 keV/μm),以高吸收剂量率(1~2 Gy/min)靶向照射部位[6],导致肿瘤细胞DNA损伤,激活cGAS-STING-IRF3-Type Ⅰ干扰素(interferon,IFN)信号级联反应,招募调节性T细胞(regulatory T cells, Tregs)、髓源性抑制细胞(myeloid-derived suppressor cells, MDSC)等免疫抑制细胞,诱导适应性免疫反应[7-8],同时引起TIME中PD-L1表达上调,负性调节肿瘤浸润T细胞引起肿瘤耐药或复发[5, 9]。因此,多个研究证明了EBRT与ICI的协同作用[10-11]。Twyman-Saint等[12]发现,PD-L1抗体的加入可逆转EBRT联合CTLA-4抗体引起的T细胞耗竭,增加黑色素瘤对联合治疗的响应率。然而EBRT作为一种局部治疗方式,即便通过免疫介导引起“远隔效应”,也仅有少数患者能因此获益[13-14]。
靶向放射性核素治疗(targeted radionuclide therapy, TRT)是一种内放射治疗,其中放射性药物通过全身给药特异性定位于靶点,向肿瘤传递细胞毒性辐射。TRT以低吸收剂量率(<1 Gy/h)长时间照射靶部位,射线的类型与放射性核素有关,包括α、β粒子及俄歇电子。LET及最大穿透深度也与核素衰变类型相关,α粒子具有较高的LET(50~230 keV/μm)和较小的穿透深度(50~100 μm);β粒子则具有更低的LET(0.2 keV/μm)和几十至数百个细胞(mm级别)的穿透距离;俄歇电子的LET为4~25 keV/μm,组织穿透最大深度<1 μm[6]。因此,EBRT对于TIME的调节作用不能简单地外推至TRT[15-16]。研究发现,高剂量TRT诱导DNA双链断裂,可上调膜联蛋白A1及钙网蛋白[17],激活Ⅰ型IFN,其幅度和时间过程与EBRT相当, 而低剂量的TRT则表现出明显的免疫调节作用,包括促炎细胞因子及细胞毒性T细胞(cytotoxic T lymphocytes,CTLs)的浸润[18-19]。然而,EBRT通过同源重组、非同源末端连接及碱基切除修复诱导DNA双链修复,TRT却通过跨损伤合成修复受损的DNA[20]。同时,Grzmil等[20]通过蛋白质组学研究发现,EBRT与TRT诱导了不同信号通路的激活,TRT主要影响表皮生长因子受体、丝裂原活化蛋白激酶、整合素和雌激素受体的信号转导。
本文将聚焦于该领域最新研究进展,对TRT联合PD-L1抗体治疗的模式及其机制进行综述,以期指导临床实践。
1. 靶向治疗放射性药物联合ICI治疗
1.1 β核素放射性药物联合ICI治疗
1.1.1 碘[131I]
131I衰变发射β粒子及γ光子,是最早用于TRT的放射性核素。Rouanet等[17]比较了131I-ICF01012与ICI的不同组合方案,发现无论是否加入PD-1/PD-L1抗体,对于治疗效果均无显著影响,但观察到了TRT联合CTLA-4抗体后T细胞衰竭相关基因CD274、LAG3和Eomes增加。而131I-MnO2-BSA作为一种放射增敏剂,可改善肿瘤乏氧,诱导肿瘤细胞免疫原性死亡,上调PD-L1的表达,抑制原发及转移瘤的生长[21]。
1.1.2 钇[90Y]
90Y具有纯β发射、能量强、半衰期短的特点,在Patel等[19]的研究中,发现中等剂量的EBRT与低剂量90Y-NM600(1.85 MBq)对于提高ICI疗效的作用是互补的。具体来说,联合治疗增加了总免疫细胞、CTLs、效应记忆T细胞(effector memory T cell, TEM)和γδ T细胞的数量,进而增加IFN-γ分泌,起到缓解肿瘤负担及减少自发转移的作用,联合中等剂量EBRT诱导远隔效应,可进一步缓解原发及转移瘤负担[19]。另有研究将此策略应用于Lewis肺癌模型治疗,仅用EBRT联合CTLA-4抗体治疗能够减少肿瘤转移,但在联合了90Y-NM600治疗后,能达到肿瘤完全缓解并诱导免疫记忆[22]。但Potluri等[23]研究发现,90Y-NM600联合PD-1抗体治疗对前列腺癌无效,其原因是PD-1抗体激活了Tregs,从而可导致免疫抑制。
1.1.3 镥[177Lu]
177Lu是最常用的TRT核素,其标记的探针177Lu-DOTATATE[24]和177Lu-PSMA-617[25]已获得美国FDA批准分别用于神经内分泌瘤及转移性去势抵抗性前列腺癌(metastatic castration-resistant prostate cancer, mCRPC)。其中177Lu-DOTATATE联合纳武单抗(Nivolumab) 的Ⅰ期临床试验证明了其安全性,在晚期神经内分泌肿瘤及广泛期小细胞肺癌中显示出抗肿瘤效果,总缓解率为14.3%(NCT03325816)[26]。177Lu-DOTATATE与伊匹单抗、纳武单抗联合使用在转移性Merkel细胞癌[27]、侵袭性垂体瘤患者[28]中能够安全且有效地缓解肿瘤进展。目前仍有几项177Lu-DOTATATE联合PD-1/PD-L1抗体治疗多种恶性肿瘤的临床试验(NCT04261855,NCT03457948,NCT05583708,NCT05142696,NCT04525638) 正在进行中。
Prasad等[29]在帕博利珠单抗(Pembrolizumab)或奥拉帕尼(olaparib)治疗无效的前列腺癌患者中,联合使用177Lu-PSMA-617治疗后前列腺特异性抗原水平趋于稳定。目前联合177Lu-PSMA-617及ICI用于mCRPC患者治疗的多项临床试验(NCT03805594,NCT03658447,NCT05150236)正在开展中。
Chen等[30]用177Lu-EB-RGD联合多剂量PD-L1抗体在鼠结直肠癌模型中诱导CD8+T细胞浸润,显著抑制了肿瘤生长,且提出TRT与ICI的给药时间窗对于治疗效果至关重要的观点。在此基础上,本研究团队进一步探索了177Lu-DOTA-EB-cRGDfK(177Lu-DER)联合治疗的给药策略,在体内外证明了放射性核素刺激后PD-L1表达呈时间及剂量依赖性上调,在TRT后4 h通过尾静脉注射PD-L1抗体能够大大提高联合治疗的疗效,联合治疗组小鼠血清促炎细胞因子、CTLs及CD4+辅助T细胞(helper T cells, Th1)浸润增加,肿瘤完全缓解并获得特异性免疫记忆效应[31]。随后用64Cu-DOTA-EB-cRGDfK(64Cu-DER)验证了该给药策略的有效性,提示该策略可推广至不同的放射性核素标记的探针中[32]。
此外,177Lu-DOTA-Folate[33]、177Lu-DOTA-Y003[34]、177Lu-h8C3[35]、177Lu-LLP2A[36]及177Lu-DNP-DOTA-BSA[37]联合ICI治疗均可抑制肿瘤生长并延长荷瘤小鼠生存期。
1.2 α核素放射性药物联合ICI治疗
1.2.1 锕[225Ac]
由于α射线独特的优势,包括能量高、射程短、能够诱导DNA双链不可修复的断裂等[38],α-TRT成为新的研究热点。与β-TRT相比,α-TRT剂量极低,225Ac-PSMA-617(30 kBq)联合PD-1抗体在RM1-PGLS模型中能够抑制肿瘤生长,达到部分完全缓解[39]。然而225 Ac-DOTA-anti-PD-L1 Ab (14.8 kBq)联合PD-L1抗体(322 μg)同时给药却降低了小鼠的生存率[40]。
1.2.2 砹[211At]
多聚ADP核糖聚合酶靶向的探针211 At-MM4导致的DNA损伤,激活了先天免疫反应,CD4+、CD8+ T细胞及巨噬细胞浸润增加,联合PD-1抗体治疗U87MG脑胶质瘤模型达到了完全缓解,65 d无进展[41]。Zhang等[42]开发的基于锰基纳米的放射免疫治疗促进剂211 At-ATE-MnO2-BSA,联合了α-TRT、化学动力治疗及PD-L1抗体治疗。研究发现,211 At-ATE-MnO2-BSA激活了树突状细胞(dendritic cells, DCs),与PD-L1抗体联合使用可进一步增加CTLs、促炎细胞因子及TEM浸润,有效抑制了肿瘤的生长、转移及复发[42]。
1.2.3 镭[223Ra]
二氯化镭(Xofigo, 223RaCl2)经美国FDA批准已用于治疗mCRPC的骨转移,223Ra处理后促进了CTLs的杀伤作用,增加了主要组织相容性复合体(major histocompatibility complex,MHC)-Ⅰ和钙网蛋白的表达[43]。在临床研究中发现,经223Ra治疗的患者免疫抑制性T细胞(表达TIM-3、PD-L1和PD-1)比例增加,同时Tregs及MDSC浸润增加,联合PD-L1抗体能够改善治疗效果[44-45]。在一项Ⅰb期临床研究(NCT02814669)中,评估了223Ra联合阿替利珠单抗(Atezolizumab)在mCRPC患者中的安全性和有效性,但联合治疗并未表现出更好的疗效,所有治疗组的中位总生存期为16.3个月,中位无进展生存期为3个月,但却增加了治疗相关毒性[46]。同时研究也发现产生治疗相关不良反应主要与阿替利珠单抗有关,因此目前正在进行的其他临床研究将Xofigo与帕博利珠单抗(NCT03996473)、纳武单抗(NCT04109729)或阿维单抗(NCT04071236)联合使用,用于晚期前列腺癌及非小细胞肺癌的骨转移治疗。
1.2.4 其他α核素
联合治疗的给药策略也是影响疗效的重要因素,剂量分割是提高EBRT联合ICI的常见方案,而对于α-TRT,一次给药效果优于多次给药。212 Pb-VMT01联合CTLA-4及PD-1抗体治疗后,43%的肿瘤完全缓解,而接受多次给药方案的肿瘤最终发生进展[47]。
Nosanchuk等[48]则发现,基于213 Bi的α-TRT与联合CTLA-4抗体的治疗效果无差异。213Bi的免疫调节作用依赖于损伤相关的分子模式(damage associa-ted molecular patterns, DAMPs)的释放并激活DCs,治疗后肿瘤组织Tregs下调,白细胞介素(interleukin,IL) -2、趋化因子C-C-基元配体(chemokine C-C-motif ligand, CCL) -5及IFN-γ短暂上调,产生肿瘤杀伤作用[49-50]。
相似的机制在227Th中也得到了验证,MSLN-TTC处理后IL-6、CCL20、CXCL10和STING相关基因在体外上调,DAMPs上调导致DCs活化[51-52]。MSLN-TTC治疗后检测到CD103+ DCs迁移及CTLs的浸润,联合PD-L1抗体后进一步增强这种效应,并观察到IFN-γ、CCL3、CCL4、IL-2、IL-5和IL-10的上调,部分肿瘤完全缓解[51]。
2. 靶向诊断放射性药物联合ICI治疗
据文献报道,高剂量的经典诊断探针2-[18F]FDG (74-148 MBq)治疗可抑制肿瘤生长并适度延长生存期,提示诊断核素在肿瘤治疗中具有较大潜力[53-55]。如图 1所示,本研究团队创新性地采用2-[18F]FDG联合PD-L1抗体治疗荷瘤小鼠,以静脉注射37 MBq或18.5 MBq 2-[18F]FDG后4 h联合400 μg PD-L1抗体治疗为一个疗程,两个疗程后(d0及d4)部分肿瘤完全缓解(5/8或4/8),且治愈后再次接种肿瘤细胞未发现肿瘤生长[56]。进一步研究发现,联合治疗组小鼠脾脏内的TEM(CD8+/CD4+CD44highCD62Llow)维持在较高水平,提示小鼠有免疫记忆产生;在治疗过程中,血清中促炎细胞因子IFN-γ、肿瘤坏死因子(tumor necrosis factor,TNF) -α及IL-6,TIME中Th1及CTLs于7 d内维持在较高水平,而单独2-[18F]FDG或PD-L1治疗组的细胞因子水平和CTLs水平轻度增高并于7 d内耗竭。Tregs(CD45+CD4+FOXP3+)、M2型巨噬细胞(CD206+F4/80+)及MDSC(CD45+CD11b+Gr-1+)仅在联合治疗组中下降,M1型巨噬细胞(iNOS+F4/80+)和DCs(CD80+CD86+)则显著上调。以上发现提示联合治疗对TIME的调控作用,相比于单独治疗组,联合治疗不仅更大程度地激活了小鼠的适应性免疫,还降低了免疫抑制性细胞水平,改善了免疫治疗的耐药性。
图 1 2-[18F]FDG联合PD-L1 ICI治疗可显著延缓肿瘤生长,提高荷瘤小鼠总生存期A.MC38荷瘤小鼠的治疗程序和时间表示意图;B.不同治疗组MC38荷瘤小鼠的个体肿瘤生长情况以及90 d存活率(αP指PD-L1抗体剂量为10 mg/kg,αP##指PD-L1抗体剂量为20 mg/kg;18F-F指2-[18F]FDG剂量为925 MBq/kg,18F-F##指2-[18F]FDG剂量为1850 MBq/kg;@4 h指PD-L1抗体与2-[18F]FDG的给药时间窗为4 h);C.2-[18F]FDG诱导MC38荷瘤小鼠免疫治疗的时间依赖性肿瘤生长曲线和生存曲线;D.ELISA法检测血液中细胞因子IFN-γ、TNF-α、IL-6水平的动态变化;E.记忆性T细胞浸润的流式细胞术分析(CD4+CD44highCD62Llow和CD8+CD44highCD62Llow);F.用FlowJo v10软件定量分析脾脏总细胞中CD4+CD44highCD62Llow细胞和CD8+CD44highCD62Llow细胞比例;G.治愈小鼠的左后侧在第91天再次接种MC38细胞,并监测至第150天;H.2-[18F]FDG联合PD-L1单抗可增强持久免疫记忆
PD-L1:程序性死亡受体配体1;IFN:干扰素;TNF:肿瘤坏死因子;IL:白细胞介素;*P<0.05;**P<0.01;***P<0.001;****P<0.0001本课题组进一步探究了2-[18F]FDG的免疫调节作用,发现2-[18F]FDG在体外可导致DNA损伤,但仍保持复制及自我修复能力(图 2A, 2B)。同时,2-[18F]FDG通过激活NF-κB P65通路,与IRF3相互作用,促进PD-L1的转录,在体外呈时间及剂量依赖性上调;进一步研究发现,STAT1、STAT3和IRF1的敲低影响NF-κB P65的磷酸化(图 2C, 2D及图 3),因此PD-L1的上调也受STAT1/3-IRF1通路调控[56]。
本课题组亦探索了纯发射γ射线的核素99mTc标记的RGD对TIME的调节作用,发现同2-[18F]FDG一样,99mTc刺激PD-L1在多种肿瘤细胞系中上调。随后比较了不同联合治疗方案的疗效,发现18.5 MBq或37 MBq 99mTc-RGD联合400 μg PD-L1抗体在4 h时间窗给药效果最佳,部分小鼠的肿瘤完全治愈(6/8)且90 d内无复发[57]。
3. 小结与展望
总结近5年发表的放射性药物联合ICI协同抗肿瘤治疗的临床前研究发现,该类研究主要围绕治疗核素展开,包括经典的β核素(177Lu、90Y)以及α核素(211At、225Ac)等(表 1)。TRT上调了PD-L1表达,增加CTLs及Th1细胞浸润,为后续ICI治疗提供了免疫原性微环境。联合治疗可进一步调控TIME,增加促炎细胞因子、TEM、M1巨噬细胞等浸润,下调Tregs及MDSC,有效抑制肿瘤生长,延长生存期,产生免疫记忆效应,部分研究甚至达到完全缓解。然而,也有研究指出,联合治疗未能正向调控TIME,未能提高TRT的疗效[23, 35, 48]。
表 1 近5年发表的放射性药物联合ICI治疗的临床前研究第一作者 放射性药物 射线类型 ICI 肿瘤类型 给药方案 TIME变化 治疗效果 Wen[56] 2-[18F] β/γ anti-PD-L1 MC38
CT262-[18F]FDG(37 MBq)给药后4 h静脉注射anti-PD-L1 (400 μg),共2个疗程(d0, d4) PD-L1、CD8+、CD4+ T细胞上调,DCs、M1巨噬细胞上调,促炎细胞因子上调,Tregs、MDSC下调 抑制肿瘤生长,延长生存期,产生免疫记忆 文雪君[57] 99mTc-RGD γ anti-PD-L1 MC38 99mTc-RGD(18.5或37 MBq)给药后4 h静脉注射anti-PD-L1(400 μg),共2个疗程(d0, d4) PD-L1上调 完全缓解率为75%,90 d内无复发 Wen[32] 64Cu-DOTA-EB-cRGDfK β anti-PD-L1 MC38 TRT(18.5 MBq)后4 h静脉注射anti-PD-L1(200 μg) PD-L1上调,CD8+及CD4+ T细胞上调,Tregs下调,促炎细胞因子上调 完全缓解率为100%, 生存率为100%, 产生免疫记忆 Wen[31] 177Lu-DOTA-EB-cRGDfK β anti-PD-L1 MC38
CT26TRT(9.25 MBq)后4 h静脉注射anti-PD-L1(200 μg) PD-L1上调,CD8+及CD4+T细胞上调,Tregs下调,促炎细胞因子上调 完全缓解率为100%, 生存率为100%, 产生免疫记忆 Wen[58] 131I-αPD-L1 β anti-PD-L1 MC38
CT26TRT(11.1 MBq)与anti-PD-L1(200 μg)同时静脉注射给药 PD-L1上调 延长生存期 Choi[36] 177Lu-LLP2A β anti-CTLA-4+anti-PD-1/PD-L1 B16F10 TRT(30 MBq)在d0给药,ICI(各200 μg)在d1、d4、d7腹腔注射给药 - 显著提高生存率 Guzik[33] 177Lu-DOTA-folate β anti-CTLA-4 NF9006 TRT(5 MBq)在d0给药,anti-CTLA-4(200 μg)在d1、d4、d7腹腔注射给药 - 抑制肿瘤生长,延长中位生存期 Ren[34] 177Lu-DOTA-Y003 β anti-PD-L1 MC38 TRT(3.7 MBq)在d0、d8给药,anti-PD-L1(100 μg)在d2、d4、d6、d10、d12、d14腹腔注射给药 PD-L1上调,CD8+及CD4+ T细胞上调 抑制肿瘤生长,生存率为100% Czernin[39] 225Ac-PSMA-617 α anti-PD-1 RM1-PGLS TRT(30 kBq)在d0给药,anti-PD-1(200 μg)在d1、d4、d8、d11腹腔注射给药 - 抑制肿瘤生长,25%完全缓解 Vito[37] 177Lu-DNP-DOTA-BSA β anti-CTLA-4+anti-PD-L1 E0771 TRT(4.4 MBq)在d0、d4给药,ICI(各200 μg)从d2开始每3天腹腔给药1次,共10次 CD4+T细胞、巨噬细胞及MDSC下调 延长生存期 Brown[22] 90Y-NM600 β anti-CTLA-4 LLC 在d0进行EBRT(12 Gy)以及TRT (1.85 MBq),anti-CTLA-4(200 μg)在d3、d6、d9腹腔给药 - 减少肿瘤转移,产生免疫记忆 Rouanet[17] 131I-ICF01012 β anti-CTLA-4+anti-PD-1/PD-L1 B16F10 TRT(18.5 MBq)在d0给药,ICI(各200 μg)在d-4、d0、d4、d8腹腔给药 T细胞衰竭相关基因CD274,LAG3和Eomes增加 延长生存期 Potluri[23] 90Y-NM600 β anti-PD-1 TRAMP-C1
Myc-CaPTRT(9.25 MBq)在d0给药,anti-PD-1(200 μg)在d0、d3、d6腹腔给药 CD8+ T细胞、Tregs细胞上调,PD-L1上调 未提高疗效 Chen[30] 177Lu-EB-RGD β anti-PD-L1 MC38 TRT(18.5 MBq)在d0给药,anti-PD-L1(200 μg)在d1、d4、d7腹腔给药 CD8+ T细胞浸润,PD-L1上调 抑制肿瘤生长,生存率为100% Li[47] 212Pb-VMT01 α anti-CTLA-4+anti-PD-1 B16F10 TRT(4.1 MBq)在d0给药,ICI(各200 μg)每周2次腹腔给药 CD3+、CD4+、CD8+淋巴细胞上调 43%完全缓解,延长生存期,产生免疫记忆 Dabagian[41] 211At-MM4 α anti-PD-1 U87MG TRT(0.72 MBq)在d0给药,anti-PD-1(200 μg)在d-3、d0、d3腹腔给药 PD-L1上调,CD8+及CD4+ T细胞上调 完全缓解率为100% Lejeune[51] MSLN-TTC
(227Th)α anti-PD-L1 MC38-hMSLN TRT(5 kBq)在d0给药,anti-PD-L1(30 μg)每周2次腹腔给药 CD8+T细胞上调,IFNγ、CCL3、CCL4、IL-2、IL-5和IL-10上调,TGF-β和FOXP3上调 58.3%完全缓解,延长生存期 Malo[35] 177Lu-h8C3
225Ac-h8C3β
αanti-PD-1 Cloudman S91 177Lu(3.7 MBq)在d0、d7给药,anti-PD-1(250 μg)在d1、d4、d7腹腔给药 未观察到肿瘤T细胞浸润增加 177Lu抑制肿瘤生长,延长生存期,225Ac联合治疗无效 Patel[19] 90Y-NM600 β anti-CTLA-4 + anti-PD-L1 B78
NXS2
4T1TRT(1.85 MBq)在d0给药,anti-CTLA-4(200 μg)在d3、d6、d9腹腔给药;EBRT (12 Gy)及TRT(1.85 MBq)在d0给药,anti-CTLA-4(200 μg)在d3、d6、d9腹腔给药 促炎细胞因子(IFN-γ, IL-10)的产生显著增加,效应T细胞浸润,联合中等剂量EBRT诱导远隔效应 显著抑制肿瘤生长,延长生存期,产生免疫记忆,原发及对侧肿瘤均缓解(46.7%完全缓解) Nosanchuk[48] 213Bi-8C3 α anti-CTLA-4 B16-F10 TRT(5.55 MBq),anti-CTLA-4(100 μg)在d1、d5、d7腹腔给药 - TRT及联合治疗均减少肺转移,但二者无差异 Zhang[21] 131I- MnO2-BSA β anti-PD-L1 4T1 TRT(18.5 MBq)在d0给药,anti-PD-L1(20 μg)在d1、d3、d5腹腔给药 CTLs浸润增加,Tregs、F4/80+ TAM下调,PD-L1上调,TNF-α、IFN-γ上调 抑制原发性肿瘤和远处肿瘤生长 Zhang[42] 211At-ATE-MnO2-BSA α anti-PD-L1 4T1
CT26TRT(555 kBq)在d0给药,anti-PD-L1(75 μg)在d1、d3、d5腹腔给药 CTLs浸润增加,TNF-α、IFN-γ上调,Tregs无变化,TEM浸润增加,TCM减少 有效抑制原发性肿瘤和远处肿瘤的生长,产生了长期免疫记忆 注:均以第一次TRT治疗为d0,d-3为TRT给药前3 d,d-4为TRT给药前4 d,所有TRT均是静脉注射给药,均估算小鼠体质量为20 g换算剂量;PD-1:程序性死亡[蛋白]-1;CTLA-4:细胞毒性T淋巴细胞抗原4;TRT:靶向放射性核素治疗;ICI:免疫检查点抑制剂;DCs:树突状细胞;Tregs:调节性T细胞;MDSC:髓源性抑制细胞;EBRT:外照射放疗;LAG3:淋巴细胞激活基因-3;CCL:趋化因子C-C-基元配体;TGF-β:转化生长因子-β;TEM:效应记忆T细胞;TCM:中央记忆T细胞;TAM:肿瘤相关巨噬细胞;CTLs:细胞毒性T淋巴细胞;FOXP3:叉头蛋白P3;Emoes:脱中胚蛋白;IFN、TNF、IL、PD-L1:同图 1 本团队既往研究发现,131I刺激了肿瘤细胞PD-L1表达呈时间及剂量依赖性上调[58]。故在此基础上,进一步选用β核素177Lu及64Cu进行探索,发现64Cu不仅可用于诊断,还具有治疗潜力[59],用64Cu-DER联合PD-L1抗体的协同抗肿瘤治疗大大提升了64Cu-TRT的疗效[32]。此外,基于2-[18F]FDG的相关研究结果[53-55],本研究团队发现,2-[18F]FDG诱导PD-L1的表达上调由NF-κB/IRF3和STAT1/3-IRF1信号通路介导,与DNA损伤通路激活有关,且放射性刺激与PD-L1抗体的给药时间窗对于治疗效果至关重要。在2-[18F]FDG刺激下,PD-L1上调需要一定时间,而18F半衰期短,难以长时间诱导PD-L1上调,因此4 h的时间窗最为合适[56]。
综上所述,诊断放射性药物联合PD-L1抗体的免疫治疗新范式可以调控TIME,显著提高疗效。与TRT相比,诊断放射性药物具有多种优势,包括可及性高,制备简单及血液毒性小等,如能将诊断性核素标记的PET/SPECT示踪剂应用于肿瘤联合治疗,将极大拓宽其应用范围,改善现有治疗性核素产量有限,特别是我国目前严重依赖进口的现状,拓展传统的肿瘤治疗模式。因此,未来研究中应进一步拓展诊断放射性药物联合免疫治疗的组合,探索不同核素对肿瘤细胞及微环境中其他细胞的影响,促进此种治疗新范式的临床转化。
作者贡献:曾馨莹、文雪君负责文献检索、论文撰写及修订;郭志德、张现忠负责论文选题和审校。利益冲突:所有作者均声明不存在利益冲突 -
图 1 2-[18F]FDG联合PD-L1 ICI治疗可显著延缓肿瘤生长,提高荷瘤小鼠总生存期
A.MC38荷瘤小鼠的治疗程序和时间表示意图;B.不同治疗组MC38荷瘤小鼠的个体肿瘤生长情况以及90 d存活率(αP指PD-L1抗体剂量为10 mg/kg,αP##指PD-L1抗体剂量为20 mg/kg;18F-F指2-[18F]FDG剂量为925 MBq/kg,18F-F##指2-[18F]FDG剂量为1850 MBq/kg;@4 h指PD-L1抗体与2-[18F]FDG的给药时间窗为4 h);C.2-[18F]FDG诱导MC38荷瘤小鼠免疫治疗的时间依赖性肿瘤生长曲线和生存曲线;D.ELISA法检测血液中细胞因子IFN-γ、TNF-α、IL-6水平的动态变化;E.记忆性T细胞浸润的流式细胞术分析(CD4+CD44highCD62Llow和CD8+CD44highCD62Llow);F.用FlowJo v10软件定量分析脾脏总细胞中CD4+CD44highCD62Llow细胞和CD8+CD44highCD62Llow细胞比例;G.治愈小鼠的左后侧在第91天再次接种MC38细胞,并监测至第150天;H.2-[18F]FDG联合PD-L1单抗可增强持久免疫记忆
PD-L1:程序性死亡受体配体1;IFN:干扰素;TNF:肿瘤坏死因子;IL:白细胞介素;*P<0.05;**P<0.01;***P<0.001;****P<0.0001表 1 近5年发表的放射性药物联合ICI治疗的临床前研究
第一作者 放射性药物 射线类型 ICI 肿瘤类型 给药方案 TIME变化 治疗效果 Wen[56] 2-[18F] β/γ anti-PD-L1 MC38
CT262-[18F]FDG(37 MBq)给药后4 h静脉注射anti-PD-L1 (400 μg),共2个疗程(d0, d4) PD-L1、CD8+、CD4+ T细胞上调,DCs、M1巨噬细胞上调,促炎细胞因子上调,Tregs、MDSC下调 抑制肿瘤生长,延长生存期,产生免疫记忆 文雪君[57] 99mTc-RGD γ anti-PD-L1 MC38 99mTc-RGD(18.5或37 MBq)给药后4 h静脉注射anti-PD-L1(400 μg),共2个疗程(d0, d4) PD-L1上调 完全缓解率为75%,90 d内无复发 Wen[32] 64Cu-DOTA-EB-cRGDfK β anti-PD-L1 MC38 TRT(18.5 MBq)后4 h静脉注射anti-PD-L1(200 μg) PD-L1上调,CD8+及CD4+ T细胞上调,Tregs下调,促炎细胞因子上调 完全缓解率为100%, 生存率为100%, 产生免疫记忆 Wen[31] 177Lu-DOTA-EB-cRGDfK β anti-PD-L1 MC38
CT26TRT(9.25 MBq)后4 h静脉注射anti-PD-L1(200 μg) PD-L1上调,CD8+及CD4+T细胞上调,Tregs下调,促炎细胞因子上调 完全缓解率为100%, 生存率为100%, 产生免疫记忆 Wen[58] 131I-αPD-L1 β anti-PD-L1 MC38
CT26TRT(11.1 MBq)与anti-PD-L1(200 μg)同时静脉注射给药 PD-L1上调 延长生存期 Choi[36] 177Lu-LLP2A β anti-CTLA-4+anti-PD-1/PD-L1 B16F10 TRT(30 MBq)在d0给药,ICI(各200 μg)在d1、d4、d7腹腔注射给药 - 显著提高生存率 Guzik[33] 177Lu-DOTA-folate β anti-CTLA-4 NF9006 TRT(5 MBq)在d0给药,anti-CTLA-4(200 μg)在d1、d4、d7腹腔注射给药 - 抑制肿瘤生长,延长中位生存期 Ren[34] 177Lu-DOTA-Y003 β anti-PD-L1 MC38 TRT(3.7 MBq)在d0、d8给药,anti-PD-L1(100 μg)在d2、d4、d6、d10、d12、d14腹腔注射给药 PD-L1上调,CD8+及CD4+ T细胞上调 抑制肿瘤生长,生存率为100% Czernin[39] 225Ac-PSMA-617 α anti-PD-1 RM1-PGLS TRT(30 kBq)在d0给药,anti-PD-1(200 μg)在d1、d4、d8、d11腹腔注射给药 - 抑制肿瘤生长,25%完全缓解 Vito[37] 177Lu-DNP-DOTA-BSA β anti-CTLA-4+anti-PD-L1 E0771 TRT(4.4 MBq)在d0、d4给药,ICI(各200 μg)从d2开始每3天腹腔给药1次,共10次 CD4+T细胞、巨噬细胞及MDSC下调 延长生存期 Brown[22] 90Y-NM600 β anti-CTLA-4 LLC 在d0进行EBRT(12 Gy)以及TRT (1.85 MBq),anti-CTLA-4(200 μg)在d3、d6、d9腹腔给药 - 减少肿瘤转移,产生免疫记忆 Rouanet[17] 131I-ICF01012 β anti-CTLA-4+anti-PD-1/PD-L1 B16F10 TRT(18.5 MBq)在d0给药,ICI(各200 μg)在d-4、d0、d4、d8腹腔给药 T细胞衰竭相关基因CD274,LAG3和Eomes增加 延长生存期 Potluri[23] 90Y-NM600 β anti-PD-1 TRAMP-C1
Myc-CaPTRT(9.25 MBq)在d0给药,anti-PD-1(200 μg)在d0、d3、d6腹腔给药 CD8+ T细胞、Tregs细胞上调,PD-L1上调 未提高疗效 Chen[30] 177Lu-EB-RGD β anti-PD-L1 MC38 TRT(18.5 MBq)在d0给药,anti-PD-L1(200 μg)在d1、d4、d7腹腔给药 CD8+ T细胞浸润,PD-L1上调 抑制肿瘤生长,生存率为100% Li[47] 212Pb-VMT01 α anti-CTLA-4+anti-PD-1 B16F10 TRT(4.1 MBq)在d0给药,ICI(各200 μg)每周2次腹腔给药 CD3+、CD4+、CD8+淋巴细胞上调 43%完全缓解,延长生存期,产生免疫记忆 Dabagian[41] 211At-MM4 α anti-PD-1 U87MG TRT(0.72 MBq)在d0给药,anti-PD-1(200 μg)在d-3、d0、d3腹腔给药 PD-L1上调,CD8+及CD4+ T细胞上调 完全缓解率为100% Lejeune[51] MSLN-TTC
(227Th)α anti-PD-L1 MC38-hMSLN TRT(5 kBq)在d0给药,anti-PD-L1(30 μg)每周2次腹腔给药 CD8+T细胞上调,IFNγ、CCL3、CCL4、IL-2、IL-5和IL-10上调,TGF-β和FOXP3上调 58.3%完全缓解,延长生存期 Malo[35] 177Lu-h8C3
225Ac-h8C3β
αanti-PD-1 Cloudman S91 177Lu(3.7 MBq)在d0、d7给药,anti-PD-1(250 μg)在d1、d4、d7腹腔给药 未观察到肿瘤T细胞浸润增加 177Lu抑制肿瘤生长,延长生存期,225Ac联合治疗无效 Patel[19] 90Y-NM600 β anti-CTLA-4 + anti-PD-L1 B78
NXS2
4T1TRT(1.85 MBq)在d0给药,anti-CTLA-4(200 μg)在d3、d6、d9腹腔给药;EBRT (12 Gy)及TRT(1.85 MBq)在d0给药,anti-CTLA-4(200 μg)在d3、d6、d9腹腔给药 促炎细胞因子(IFN-γ, IL-10)的产生显著增加,效应T细胞浸润,联合中等剂量EBRT诱导远隔效应 显著抑制肿瘤生长,延长生存期,产生免疫记忆,原发及对侧肿瘤均缓解(46.7%完全缓解) Nosanchuk[48] 213Bi-8C3 α anti-CTLA-4 B16-F10 TRT(5.55 MBq),anti-CTLA-4(100 μg)在d1、d5、d7腹腔给药 - TRT及联合治疗均减少肺转移,但二者无差异 Zhang[21] 131I- MnO2-BSA β anti-PD-L1 4T1 TRT(18.5 MBq)在d0给药,anti-PD-L1(20 μg)在d1、d3、d5腹腔给药 CTLs浸润增加,Tregs、F4/80+ TAM下调,PD-L1上调,TNF-α、IFN-γ上调 抑制原发性肿瘤和远处肿瘤生长 Zhang[42] 211At-ATE-MnO2-BSA α anti-PD-L1 4T1
CT26TRT(555 kBq)在d0给药,anti-PD-L1(75 μg)在d1、d3、d5腹腔给药 CTLs浸润增加,TNF-α、IFN-γ上调,Tregs无变化,TEM浸润增加,TCM减少 有效抑制原发性肿瘤和远处肿瘤的生长,产生了长期免疫记忆 注:均以第一次TRT治疗为d0,d-3为TRT给药前3 d,d-4为TRT给药前4 d,所有TRT均是静脉注射给药,均估算小鼠体质量为20 g换算剂量;PD-1:程序性死亡[蛋白]-1;CTLA-4:细胞毒性T淋巴细胞抗原4;TRT:靶向放射性核素治疗;ICI:免疫检查点抑制剂;DCs:树突状细胞;Tregs:调节性T细胞;MDSC:髓源性抑制细胞;EBRT:外照射放疗;LAG3:淋巴细胞激活基因-3;CCL:趋化因子C-C-基元配体;TGF-β:转化生长因子-β;TEM:效应记忆T细胞;TCM:中央记忆T细胞;TAM:肿瘤相关巨噬细胞;CTLs:细胞毒性T淋巴细胞;FOXP3:叉头蛋白P3;Emoes:脱中胚蛋白;IFN、TNF、IL、PD-L1:同图 1 -
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