腫瘤化療聯(lián)合免疫治療 從理論基礎(chǔ)到臨床實(shí)踐

劉瀟衍 綜述 陳閩江 王孟昭 審校

腫瘤化療聯(lián)合免疫治療 從理論基礎(chǔ)到臨床實(shí)踐

劉瀟衍 綜述 陳閩江 王孟昭 審校

在過去的幾十年里，化療是腫瘤內(nèi)科治療的基石。盡管化療療效顯著，但維持病情穩(wěn)定時(shí)間不持久。隨著對(duì)腫瘤免疫學(xué)研究的不斷深入，近年來腫瘤免疫治療再次成為熱點(diǎn)。與化療相比，免疫治療療效相對(duì)緩和，但更為持久。越來越多的研究表明化療除了對(duì)腫瘤細(xì)胞的直接殺傷作用，亦可以增加腫瘤細(xì)胞的免疫原性，抑制負(fù)性免疫信號(hào)，改變腫瘤免疫微環(huán)境，從而發(fā)揮免疫增強(qiáng)作用，為化療和免疫治療的聯(lián)合應(yīng)用奠定了理論基礎(chǔ)。本文根據(jù)已知的腫瘤免疫反應(yīng)機(jī)理和近期發(fā)現(xiàn)的化療免疫調(diào)節(jié)機(jī)制，闡述化療聯(lián)合免疫治療的理論基礎(chǔ)，并進(jìn)一步探討現(xiàn)有的關(guān)于聯(lián)合治療的基礎(chǔ)和臨床研究，從而為后續(xù)研究指明方向。

腫瘤 化療 免疫治療 協(xié)同作用

隨著對(duì)腫瘤免疫研究的不斷深入和新的免疫治療藥物不斷出現(xiàn)，腫瘤內(nèi)科治療方法變得愈加豐富，包括化療、內(nèi)分泌治療、靶向治療、免疫治療。如何將不同治療方法合理地序貫或聯(lián)合應(yīng)用以發(fā)揮最佳的治療效果，面對(duì)不同腫瘤負(fù)荷、不同腫瘤生物學(xué)行為、不同免疫狀態(tài)的患者如何制定最合理的治療策略，已成為臨床工作者亟待解決的問題。近年來一系列研究探索了化療藥物對(duì)腫瘤免疫應(yīng)答的影響，以期更好地指導(dǎo)免疫治療藥物和細(xì)胞毒性藥物的合理搭配。本文結(jié)合理論基礎(chǔ)和現(xiàn)有研究證據(jù)對(duì)化療及機(jī)體腫瘤免疫應(yīng)答的影響和免疫治療聯(lián)合化療的臨床應(yīng)用進(jìn)行綜述。

1 化療對(duì)機(jī)體腫瘤免疫應(yīng)答的影響

目前研究發(fā)現(xiàn)化療可以發(fā)揮正向免疫調(diào)節(jié)作用，增強(qiáng)機(jī)體的抗腫瘤免疫應(yīng)答（圖1），其具體作用機(jī)制可以分為兩個(gè)方面：1）腫瘤細(xì)胞自身介導(dǎo)的免疫增強(qiáng)作用，即化療可以誘導(dǎo)腫瘤細(xì)胞發(fā)生免疫原性的細(xì)胞死亡（immunogenic cell death，ICD），誘發(fā)機(jī)體的抗腫瘤免疫應(yīng)答?；A(chǔ)及臨床研究發(fā)現(xiàn)部分化療藥物可以誘發(fā)ICD，常見的包括蒽環(huán)類藥物（多柔比星、表阿霉素、柔紅霉素）、米托蒽醌、奧沙利鉑、氟尿嘧啶、伊立替康、環(huán)磷酰胺、硼替佐米等［1-5］。然而，必須注意的是同一類的化療藥物，雖然化學(xué)結(jié)構(gòu)相似，但是其誘發(fā)ICD的能力卻不同。如鉑類藥物奧沙利鉑可以誘導(dǎo)ICD，但是因?yàn)榻Y(jié)構(gòu)的差異，順鉑則不能［6］；但在給予順鉑的同時(shí)加入刺激內(nèi)質(zhì)網(wǎng)應(yīng)激反應(yīng)的藥物則可以誘導(dǎo)ICD［7］。所以藥物任何理化性質(zhì)的細(xì)小差別都可能影響其誘發(fā)ICD的能力，同一類化療藥物并非均可誘導(dǎo)ICD，繼而聯(lián)合免疫治療，還需要結(jié)合臨床前和臨床研究結(jié)果，合理地搭配應(yīng)用；2）化療雖然導(dǎo)致淋巴細(xì)胞總數(shù)減少，但可以改變各免疫細(xì)胞亞群的比例及其功能，降低外周血和腫瘤病灶免疫微環(huán)境中抑制性免疫細(xì)胞的比例，減少抑制性免疫細(xì)胞因子的分泌，增加具有抗腫瘤作用的效應(yīng)淋巴細(xì)胞，從面增強(qiáng)抗腫瘤免疫應(yīng)答［8］。

圖1 化療的免疫效應(yīng)Figure 1 Immune effects of chemotherapy

1994年Matzinger提出任何細(xì)胞誘發(fā)免疫應(yīng)答必須滿足兩個(gè)條件：免疫原性和佐劑的輔助［9］。其研究發(fā)現(xiàn)病毒感染宿主細(xì)胞后，病毒相關(guān)蛋白被呈遞到細(xì)胞表面，與細(xì)胞表面主要組織相容性復(fù)合體（major histocompatibility complex，MHC）分子結(jié)合，細(xì)胞的免疫原性增加，但這不足以誘發(fā)有效的免疫應(yīng)答；之后細(xì)胞裂解釋放一系列可溶性的，或與膜結(jié)合的信號(hào)因子，最終誘導(dǎo)機(jī)體產(chǎn)生免疫反應(yīng)。這些信號(hào)分子稱為損傷相關(guān)分子模式（damage-associated molecular patterns，DAMPs），這些分子可以與髓系和淋系來源的免疫細(xì)胞（如巨噬細(xì)胞、自然殺傷細(xì)胞和樹突細(xì)胞）表面的模式識(shí)別受體（pattern recognition recep?tors，PRRs）結(jié)合，繼而激活免疫應(yīng)答。

1.1 增加腫瘤細(xì)胞的抗原性

化療藥物誘導(dǎo)腫瘤細(xì)胞抗原性增強(qiáng)是通過不同機(jī)制實(shí)現(xiàn)的。基礎(chǔ)研究表明吉西他濱殺傷腫瘤細(xì)胞可以增加抗原表位的種類，進(jìn)而引發(fā)更強(qiáng)的免疫應(yīng)答，這種現(xiàn)象稱為抗原表位擴(kuò)增［5］。而氟尿嘧啶和阿糖胞苷則通過增加腫瘤相關(guān)抗原（如CEA、睪丸抗原）表達(dá)數(shù)量，繼而增加其抗原性［10-12］。

1.2 增加腫瘤細(xì)胞的免疫原性

既往觀點(diǎn)認(rèn)為細(xì)胞凋亡是自身程序性死亡，不會(huì)引發(fā)免疫反應(yīng)。然而后續(xù)研究發(fā)現(xiàn)某些刺激因素誘導(dǎo)下的特殊類型的細(xì)胞凋亡會(huì)釋放抗原分子和DAMPs，繼而引發(fā)機(jī)體的免疫應(yīng)答，這種凋亡稱為ICD［13］。2005年Casares等［1］發(fā)現(xiàn)將體外經(jīng)過多柔比星處理過的結(jié)直腸腺癌CT26細(xì)胞和纖維肉瘤MCA205細(xì)胞重新回輸小鼠體內(nèi)，可以使其產(chǎn)生相應(yīng)抗體，再次將未經(jīng)處理的相同腫瘤細(xì)胞輸入小鼠體內(nèi)后，腫瘤細(xì)胞無法增殖。此后諸多研究證實(shí)腫瘤細(xì)胞在化療藥物的作用下，會(huì)發(fā)生ICD。盡管ICD的形態(tài)學(xué)表現(xiàn)和生化代謝特征同細(xì)胞凋亡相似［14-15］，但腫瘤細(xì)胞裂解后釋放腫瘤抗原的同時(shí)，生成DAMPs信號(hào)分子，包括：鈣網(wǎng)蛋白（calreticulin，CRT）、ATP、高遷移率族蛋白B1（high mobility group protein B1，HMGB1）、熱休克蛋白70和90（heat shock protein，HSP70/90）等。同病毒感染后引發(fā)的免疫應(yīng)答類似，上述DAMPs信號(hào)分子可以促進(jìn)抗原提呈細(xì)胞（antigen-presenting cells，APCs）的攝取提呈抗原，進(jìn)而激活固有和適應(yīng)性免疫應(yīng)答，清除腫瘤細(xì)胞［16］。

CRT是一種主要定位于細(xì)胞內(nèi)質(zhì)網(wǎng)上的伴侶蛋白，當(dāng)內(nèi)質(zhì)網(wǎng)穩(wěn)態(tài)破壞時(shí)，會(huì)轉(zhuǎn)位到細(xì)胞膜，誘導(dǎo)巨噬細(xì)胞和樹突狀細(xì)胞吞噬凋亡細(xì)胞［17-19］。據(jù)研究報(bào)道蒽環(huán)類藥物（如多柔比星、米托蒽醌等）、奧沙利鉑、環(huán)磷酰胺可以誘導(dǎo)CRT在細(xì)胞膜表面表達(dá)，進(jìn)而引發(fā)腫瘤細(xì)胞ICD［4，19］。蒽環(huán)類藥物誘導(dǎo)CRT轉(zhuǎn)位于細(xì)胞膜的機(jī)制包括：1）細(xì)胞因子如白介素-8（IL-8）的旁分泌作用；2）內(nèi)質(zhì)網(wǎng)應(yīng)激時(shí)，真核細(xì)胞轉(zhuǎn)錄起始因子（eukaryotic initiation factor 2α，eIF2α）的磷酸化；3）細(xì)胞凋亡信號(hào)的激活［15，20］。

胞外ATP主要作用于purinergic受體，包括P2Y purinoceptor 2（P2RY2）和purinergic receptor P2X 7（P2RX7）受體。P2RY2受體介導(dǎo)的信號(hào)通路可以誘導(dǎo)前體DC細(xì)胞分化和募集，促進(jìn)中性粒細(xì)胞浸潤腫瘤組織［18，21］；P2RX7受體則可介導(dǎo)IL-1b分泌，誘導(dǎo)細(xì)胞毒性T細(xì)胞的分化［22］。有研究發(fā)現(xiàn)奧沙利鉑和米托蒽醌可以誘導(dǎo)小鼠結(jié)直腸癌腫瘤細(xì)胞自噬，并釋放ATP，促使DC細(xì)胞和T細(xì)胞浸潤［23］。

HMGB1則可激活PRRs，包括Toll樣受體4（tolllike receptor 4，TLR4），繼而增強(qiáng)樹突狀細(xì)胞的抗原提呈作用［24-25］。Yamazaki等［26］研究發(fā)現(xiàn)乳腺癌進(jìn)展時(shí)腫瘤組織內(nèi)HMGB分子表達(dá)缺失；Suzuki等［27］發(fā)現(xiàn)HMGB分子表達(dá)缺失與患者預(yù)后不佳相關(guān)。此外，研究發(fā)現(xiàn)編碼P2RX7（ATP的受體）和TLR4（HMGB1的受體）基因功能缺失的乳腺癌患者，蒽環(huán)類藥物治療后療效劣于基因正?；颊撸?5］；TLR4功能缺失的結(jié)直腸癌患者，接受含奧沙利鉑方案治療后預(yù)后較TLR4功能正常者預(yù)后差［4］。

1.3 化療藥物對(duì)腫瘤細(xì)胞的其他影響

此外，化療藥物還可以通過以下幾種方式來增強(qiáng)免疫系統(tǒng)對(duì)腫瘤細(xì)胞的識(shí)別和殺傷。1）上調(diào)腫瘤細(xì)胞表面MHCⅠ類分子表達(dá)。研究表明依托泊苷、拓?fù)涮婵?、長(zhǎng)春新堿、紫杉醇還可以通過誘導(dǎo)腫瘤細(xì)胞分泌干擾素（interferon，IFN）-b，繼而通過自分泌環(huán)的作用增加腫瘤細(xì)胞MHCⅠ分子表達(dá)［28］；2）上調(diào)B7-1等共刺激分子表達(dá)［29-30］，下調(diào)B7-H1/pro?grammed death-ligand 1（PD-L1）等負(fù)性共刺激分子表達(dá)［31］；3）部分作用于細(xì)胞DNA結(jié)構(gòu)的化療藥物可以誘導(dǎo)腫瘤細(xì)胞表達(dá)死亡受體，包括FAS受體（CD95）和TNF相關(guān)凋亡誘導(dǎo)配體的受體（TNF-relat?ed apoptosis-inducing ligand receptor，TRAIL-R）表達(dá)，介導(dǎo)免疫細(xì)胞分泌的FASL和TRAIL對(duì)腫瘤細(xì)胞的攻擊作用［32-33］。此外，研究還表明紫杉醇、順鉑、多柔比星可以促進(jìn)腫瘤細(xì)胞表面表達(dá)M6P受體（man?nose-6-phosphate receptor，M6PR），繼而增加顆粒酶-B（granzyme-B）的細(xì)胞穿透力，增加殺傷性T細(xì)胞的功能［2］。

綜上所述，化療藥物對(duì)腫瘤細(xì)胞的影響包括以下幾種途徑：1）增加腫瘤細(xì)胞表達(dá)的抗原種類和數(shù)量；2）增加腫瘤細(xì)胞釋放DAMPs，誘導(dǎo)ICD；3）上調(diào)腫瘤細(xì)胞表面MHC分子、共刺激分子、死亡受體等表達(dá)，下調(diào)腫瘤細(xì)胞表面負(fù)性共刺激分子表達(dá)。

2 化療藥物對(duì)免疫系統(tǒng)的影響

誠然，細(xì)胞毒藥物會(huì)導(dǎo)致粒系和淋巴系細(xì)胞減少，機(jī)體出現(xiàn)一過性的免疫抑制。但對(duì)于腫瘤，粒系和淋巴系的免疫細(xì)胞既有監(jiān)視殺傷腫瘤的作用，亦有促進(jìn)腫瘤免疫逃避的作用；而全身化療后隨著骨髓功能的恢復(fù)，免疫細(xì)胞亞群和功能發(fā)生改變，可打破機(jī)體對(duì)腫瘤的免疫耐受［34］。臨床研究中亦觀察到化療聯(lián)合樹突狀細(xì)胞疫苗或免疫檢查點(diǎn)抑制劑治療結(jié)直腸癌、黑色素瘤、非小細(xì)胞肺癌具有協(xié)同作用［35-37］。

盡管體外研究發(fā)現(xiàn)化療藥物，如紫杉醇可以通過抑制微管蛋白的解聚，直接促進(jìn)單核細(xì)胞分泌細(xì)胞因子IL-1β和TNF-α，并且呈劑量依賴性［38-39］。但需要強(qiáng)調(diào)的是因?yàn)榛熆梢哉T導(dǎo)腫瘤細(xì)胞發(fā)生ICD，增加其抗原性和免疫原性，激活固有免疫應(yīng)答和適應(yīng)性免疫應(yīng)答，所以化療藥物對(duì)免疫系統(tǒng)各細(xì)胞亞群的影響包括：1）化療藥物本身對(duì)髓系和淋巴系來源免疫細(xì)胞的直接影響；2）化療誘導(dǎo)腫瘤細(xì)胞ICD，繼而增強(qiáng)機(jī)體免疫應(yīng)答，間接改變各種免疫細(xì)胞亞群的比例。

如前所述，參與腫瘤免疫微環(huán)境的細(xì)胞主要包括來源于淋系和髓系的免疫細(xì)胞。淋系來源的免疫細(xì)胞包括CD4和CD8陽性的T細(xì)胞、NK細(xì)胞、部分DC細(xì)胞。其中T淋巴細(xì)胞激活后分化為CD4和CD8陽性T淋巴細(xì)胞，在不同細(xì)胞因子調(diào)控下，CD4陽性的T淋巴細(xì)胞又分化為Th1、Th2、Th17、調(diào)節(jié)性T細(xì)胞（regulatory T cell，Treg）等不同亞型，在機(jī)體抗腫瘤免疫、腫瘤免疫逃避中發(fā)揮不同作用，Th1淋巴細(xì)胞主要介導(dǎo)細(xì)胞免疫，Th2淋巴細(xì)胞主要介導(dǎo)體液免疫，Treg細(xì)胞主要抑制抗腫瘤免疫應(yīng)答，Th17細(xì)胞則具有雙向調(diào)節(jié)作用。淋巴細(xì)胞亞群的比例不同，直接影響了最終腫瘤免疫應(yīng)答的強(qiáng)度。髓系來源的免疫細(xì)胞包括單核細(xì)胞、巨噬細(xì)胞、中性粒細(xì)胞、部分DC細(xì)胞。近年來，針對(duì)腫瘤相關(guān)的髓系細(xì)胞（tumor-as?sociated myeloid cells，TAMCs）在抗腫瘤免疫應(yīng)答中的調(diào)節(jié)作用有較為深入的研究，其主要包括：1）腫瘤相關(guān)的巨噬細(xì)胞（tumor associated macrophage，TAM），其在腫瘤組織內(nèi)分化為M1型，分泌一氧化氮（NO）和活性氧（ROS）等，攻擊殺傷腫瘤細(xì)胞；還分化為M2型，分泌促進(jìn)腫瘤增殖轉(zhuǎn)移細(xì)胞因子［40］；2）髓源性抑制細(xì)胞（myeloid-derived suppressor cells，MD?SCs），抑制腫瘤組織內(nèi)T細(xì)胞功能，促進(jìn)腫瘤免疫逃避［41］；3）腫瘤相關(guān)的中性粒細(xì)胞（tumor-associated neutrophils，TANs），其在腫瘤組織內(nèi)亦分化為N1型（抑制腫瘤）和N2型（促進(jìn)腫瘤）［42］；4）腫瘤相關(guān)的樹突狀細(xì)胞（tumor associated dendritic cells，TADCs），主要表現(xiàn)為不成熟表型（immature phenotype，iDC），促進(jìn)腫瘤免疫逃避［43］。

化療對(duì)抗腫瘤免疫應(yīng)答的激活作用主要體現(xiàn)在以下兩個(gè)方面：1）正性調(diào)節(jié)識(shí)別殺傷腫瘤的免疫細(xì)胞，包括增加抗原提呈細(xì)胞（如樹突狀細(xì)胞）、殺傷性T細(xì)胞、NK細(xì)胞比例或數(shù)量，恢復(fù)其功能；2）負(fù)性調(diào)節(jié)抑制腫瘤免疫反應(yīng)的免疫細(xì)胞，包括減少M(fèi)2型巨噬細(xì)胞、MDSCs、Treg細(xì)胞的數(shù)量或比例。

2.1 對(duì)T細(xì)胞的影響

Treg細(xì)胞分泌免疫抑制因子，在腫瘤免疫逃避中發(fā)揮重要作用。一系列動(dòng)物研究發(fā)現(xiàn)化療藥物如環(huán)磷酰胺、紫杉醇、奧沙利鉑、三氧化二砷、替莫唑胺可以減少Treg細(xì)胞數(shù)量或比例［44-45］，體外研究亦觀察到環(huán)磷酰胺和奧沙利鉑可以直接抑制Treg細(xì)胞的分化［46］。臨床研究中亦發(fā)現(xiàn)蒽環(huán)類藥物、紫杉醇、氟達(dá)拉濱可以使乳腺癌、淋巴瘤等腫瘤患者Treg細(xì)胞數(shù)量或比例下降，同時(shí)可伴有CD8陽性殺傷性T細(xì)胞增多，以及NK細(xì)胞活性升高，這種反應(yīng)與療效相關(guān)［47-48］。但是需要強(qiáng)調(diào)的是，化療藥物的給藥劑量、周期對(duì)于發(fā)揮其最佳的免疫調(diào)節(jié)作用非常重要，臨床上觀察到對(duì)于腫瘤患者環(huán)磷酰胺節(jié)拍化療可以減少Treg細(xì)胞數(shù)量，恢復(fù)殺傷性T細(xì)胞和NK細(xì)胞活性［45，49］。

此外，體內(nèi)體外研究發(fā)現(xiàn)環(huán)磷酰胺可以誘導(dǎo)Th17 T細(xì)胞的分化，外周血循環(huán)和腫瘤組織內(nèi)Th17 T細(xì)胞明顯增加［50］。在乳腺癌中亦觀察到紫杉類藥物治療有效的患者中，治療后血清中IFN-γ和IL-2分泌明顯增加，促進(jìn)T細(xì)胞向Th1表型分化［3］。

2.2 對(duì)其他參與腫瘤免疫應(yīng)答細(xì)胞的影響

研究表明化療藥物多柔比星、甲氨蝶呤、絲裂霉素、紫杉醇可以上調(diào)樹突狀細(xì)胞表面MHCⅡ分子和共刺激分子CD80/CD86的表達(dá)，提高其抗原提呈能力［51］。胰腺癌患者在接受吉西他濱治療后CD14+單核細(xì)胞和CD11c+樹突狀細(xì)胞數(shù)量增加［52］。

此外，研究發(fā)現(xiàn)MDSCs和M2巨噬細(xì)胞抑制免疫應(yīng)答，分泌促進(jìn)腫瘤生長(zhǎng)的細(xì)胞因子［53］。多種化療藥物可以減少M(fèi)DSCs和M2巨噬細(xì)胞的數(shù)量，抑制其功能，促使腫瘤免疫微環(huán)境的免疫監(jiān)視和清除作用。目前發(fā)現(xiàn)紫杉類藥物、吉西他濱、5-氟尿嘧啶（5-FU）等可以減少帶瘤小鼠體內(nèi)MDSCs數(shù)量，從而減少免疫抑制性細(xì)胞因子的分泌，增強(qiáng)殺傷性T細(xì)胞和NK細(xì)胞功能［54-56］。然而在小鼠無瘤模型中，給予環(huán)磷酰胺后外周血中MDSC數(shù)量增加［57］。在接受環(huán)磷酰胺聯(lián)合多柔比星治療的患者中，亦觀察到MDSC數(shù)量增加［58］，這提示不同化療藥物對(duì)MDSC的影響可能不同，亟需進(jìn)一步深入的研究。

3 化療聯(lián)合免疫治療的臨床研究

目前臨床研究中，與化療聯(lián)合應(yīng)用的免疫治療方法主要包括：過繼細(xì)胞治療、腫瘤疫苗、免疫檢查點(diǎn)抑制劑等?；煹慕o藥劑量、周期亦不盡相同，初步可以分為免疫治療聯(lián)合標(biāo)準(zhǔn)劑量化療、高劑量化療、和低劑量化療。

3.1 標(biāo)準(zhǔn)劑量化療聯(lián)合免疫治療

標(biāo)準(zhǔn)劑量的化療可以導(dǎo)致骨髓抑制，淋巴細(xì)胞減少；此外部分化療藥物前的預(yù)處理還會(huì)應(yīng)用糖皮質(zhì)激素，這些都會(huì)引起機(jī)體的免疫抑制狀態(tài)。但標(biāo)準(zhǔn)劑量化療藥物同樣可以誘導(dǎo)腫瘤細(xì)胞發(fā)生ICD，增強(qiáng)腫瘤免疫原性，增強(qiáng)免疫治療效果。

早期臨床研究發(fā)現(xiàn)標(biāo)準(zhǔn)劑量的化療藥物可以抑制機(jī)體的免疫應(yīng)答，一項(xiàng)給予表達(dá)CEA的實(shí)體瘤患者疫苗治療的研究中發(fā)現(xiàn)，疫苗治療前接受的化療周期數(shù)越多或距離末次化療結(jié)束時(shí)間越近，疫苗誘導(dǎo)產(chǎn)生的針對(duì)CEA的T細(xì)胞數(shù)量越少［59］；在另一項(xiàng)關(guān)于表達(dá)間皮素并分泌GM-CSF的Ⅱ/Ⅲ期胰腺癌細(xì)胞疫苗的臨床研究中，給予入組患者疫苗治療，術(shù)后放化療后予以疫苗治療3次后產(chǎn)生的特異性T細(xì)胞數(shù)量相當(dāng)于放化療前給藥一次時(shí)的數(shù)量，說明放化療后患者存在免疫抑制狀態(tài)［60］。但后續(xù)越來越多的臨床研究提示標(biāo)準(zhǔn)劑量化療聯(lián)合免疫治療的療效優(yōu)于單用化療或免疫治療。一項(xiàng)納入36例Ⅱ～Ⅳ期黑色素瘤的臨床研究，一組患者第1日給予800mg/m2達(dá)卡巴嗪，后給予melan-A/MART-1/gp-100多肽疫苗；另一組患者單純予多肽疫苗治療，化療聯(lián)合免疫治療與單獨(dú)免疫治療相比，可以增加免疫應(yīng)答相關(guān)基因的表達(dá)、增加體內(nèi)特異性T細(xì)胞數(shù)量、促進(jìn)記憶性T細(xì)胞應(yīng)答，患者生存期有延長(zhǎng)的趨勢(shì)［61］。此外亦有數(shù)項(xiàng)研究探索了標(biāo)準(zhǔn)劑量化療聯(lián)合免疫檢查點(diǎn)抑制劑。一項(xiàng)轉(zhuǎn)移性黑色素瘤的研究發(fā)現(xiàn)達(dá)卡巴嗪聯(lián)合伊匹單抗治療可以延長(zhǎng)總生存期（overall survival，OS）［62］。在另外兩項(xiàng)關(guān)于非小細(xì)胞肺癌和小細(xì)胞肺癌患者的隨機(jī)對(duì)照臨床研究中，標(biāo)準(zhǔn)劑量卡鉑加用紫杉醇化療后序貫應(yīng)用伊匹單抗較化療同時(shí)給予伊匹單抗，可以延長(zhǎng)免疫相關(guān)的PFS（immune-related progression-free survival，irPFS）［37，63］。一項(xiàng)關(guān)于轉(zhuǎn)移性乳腺癌的研究中，標(biāo)準(zhǔn)劑量紫杉醇化療后給予IMP321（LAG-3抑制劑），與既往數(shù)據(jù)比較，提高了有效率；此外患者外周血中NK細(xì)胞和效應(yīng)記憶CD8 T細(xì)胞明顯增多［64］。

綜上所述，多數(shù)研究支持標(biāo)準(zhǔn)劑量化療序貫免疫治療可以起到協(xié)同作用，但值得注意的是亦有部分研究首先給予免疫治療后序貫化療，可以提高化療療效。

3.2 高劑量化療聯(lián)合免疫治療

目前臨床研究中較少應(yīng)用高劑量化療藥物聯(lián)合免疫治療。一項(xiàng)研究在白血病患者接受自體造血干細(xì)胞移植復(fù)發(fā)后，給予針對(duì)次要組織相容性抗原的過繼T細(xì)胞治療，7例患者中有5例獲得完全緩解（complete remission，CR），但后期再次復(fù)發(fā)［65］。另外2項(xiàng)研究是高劑量化療聯(lián)合自體干細(xì)胞移植后給予分泌GM-CSF自體失活腫瘤疫苗，疫苗治療后可以成功誘導(dǎo)出機(jī)體免疫反應(yīng)，患者長(zhǎng)期獲得CR［66-67］。還有一項(xiàng)針對(duì)晚期黑色素瘤患者的研究，給予大劑量環(huán)磷酰胺+氟達(dá)拉濱化療聯(lián)合全身放療（total body irra?diation，TBI），徹底清除患者體內(nèi)的免疫細(xì)胞后將體外擴(kuò)增的腫瘤浸潤淋巴細(xì)胞TIL回輸。這種方法可以最大程度促進(jìn)回輸?shù)腡IL增殖，而且早期研究顯示放化療后淋巴細(xì)胞減少比例越大，TIL回輸后治療效果越好；該研究結(jié)果顯示，化療+TIL治療組的43例黑色素瘤患者有效率為49%，化療+2 Gy TBI+過繼治療組的25例患者有效率為52%，化療+12 Gy TBI+過繼治療組的25例患者有效率為72%［68］。

3.3 低劑量化療聯(lián)合免疫治療

低劑量化療對(duì)機(jī)體主要產(chǎn)生免疫調(diào)節(jié)作用，而不是對(duì)腫瘤細(xì)胞的直接殺傷作用。早期多項(xiàng)研究證實(shí)低劑量環(huán)磷酰胺可以減少抑制性T細(xì)胞，解除免疫抑制；后續(xù)在胰腺癌、非小細(xì)胞肺癌、乳腺癌、卵巢癌、腎癌等實(shí)體瘤研究中發(fā)現(xiàn)予環(huán)磷酰胺250 mg/m2或300 mg/m2治療后序貫免疫治療，相對(duì)于直接單純免疫治療組，可以提高機(jī)體免疫應(yīng)答，增強(qiáng)免疫治療效果，帶來生存獲益［69-70］。

4 總結(jié)與展望

綜上所述，化療聯(lián)合免疫治療具有廣泛應(yīng)用前景，但是臨床上仍有一系列問題亟需解決。1）評(píng)估控制化療聯(lián)合免疫治療的不良反應(yīng)；2）如何設(shè)計(jì)最優(yōu)的化療劑量（大劑量、中等計(jì)量、小劑量）和化療給藥順序（免疫治療前/中/后、間斷大劑量、持續(xù)小劑量等），以期最大程度發(fā)揮化療的免疫激活作用；3）因?yàn)橥暾拿庖邞?yīng)答涉及到抗原釋放、攝取、提呈，T細(xì)胞激活、分化、遷移、浸潤，識(shí)別和殺傷腫瘤細(xì)胞多個(gè)環(huán)節(jié)，所以免疫治療沒有找到明確的單一療效預(yù)測(cè)分子，如何篩選合適的患者接受化療聯(lián)合免疫治療也是臨床醫(yī)生面臨的重要問題。

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（2017-02-15收稿）

（2017-04-05修回）

（編輯：孫喜佳 校對(duì)：楊紅欣）

Combining chemotherapy with immunotherapy:from bench to bedside

Xiaoyan LIU,Minjiang CHEN,Mengzhao WANG

Mengzhao WANG;E-mail:mengzhaowang@sina.com Department of Pulmonary Medicine,Peking Union Medical College Hospital,Chinese Academy of Medical Sciences,Peking Union Medical College,Beijing 100730,China

Chemotherapy has been the cornerstone of cancer treatment for decades.However,albeit remarkable,the response to chemotherapy is generally short-lived.With deepened understanding of cancer immunology,resurgence was recently witnessed in the field of cancer immunotherapy.Unlike chemotherapy,immunotherapy induces a relatively mild but stable response.Accumulating evidence reveals that apart from chemotherapy's direct cytotoxic activity,chemotherapy exerts immune-potentiating effects by increasing the immunogenicity of tumor cells or by disrupting the tumor-induced immunosuppression and altering the immune microenvironment.The latter mechanism serves as the basis for the combined use of chemotherapy and immunotherapy.In this review,we examine the rationale for combinatorial therapy in accordance with the current understanding on tumor immunity and newly discovered immune-based chemotherapeutic mechanisms.We further discuss the available preclinical and clinical studies on the combination of chemotherapy and immunotherapy for cancer treatment.We aim to provide a framework for further research.

cancer,chemotherapy,immunotherapy,synergistic activity

10.3969/j.issn.1000-8179.2017.09.177

中國醫(yī)學(xué)科學(xué)院，北京協(xié)和醫(yī)學(xué)院，北京協(xié)和醫(yī)院呼吸科（北京市100730）

王孟昭 mengzhaowang@sina.com

劉瀟衍 專業(yè)方向?yàn)楹粑到y(tǒng)腫瘤的診斷及治療。

E-mail：dr.liu-pumc@qq.com