摘要：2024年11月14日至17日，国际细胞与免疫治疗（CTI）大会在中国杭州盛大举行，汇聚了全球细胞治疗和免疫治疗领域的顶尖专家、学者和行业领袖。此次大会不仅是一个学术交流的国际平台，更是一个展示最新科研成果、推动领域发展的重要窗口。会议期间，《肿瘤瞭望·血液时

2024年11月14日至17日，国际细胞与免疫治疗（CTI）大会在中国杭州盛大举行，汇聚了全球细胞治疗和免疫治疗领域的顶尖专家、学者和行业领袖。此次大会不仅是一个学术交流的国际平台，更是一个展示最新科研成果、推动领域发展的重要窗口。会议期间，《肿瘤瞭望·血液时讯》特别邀请到德国慕尼黑大学附属医院（LMU）Marion Subklewe教授，与我们分享AdCAR-T细胞技术的原理、优势以及AML治疗未来优化方向，现整理成文，以飨读者。

Q1

Adapter CAR-T（AdCAR-T）技术在急性髓系白血病（AML）治疗中的主要优势是什么？它如何克服传统CAR-T疗法的限制？

Marion Subklewe教授：迄今为止，在急性髓系白血病（AML）治疗领域，我们在进行CAR-T细胞疗法的研究过程中，观察到的一个显著现象是，严重细胞因子释放综合征（CRS）的发生率居高不下。为应对这一挑战，我们引入了Adapter CAR-T（简称AdCAR-T）细胞技术，旨在提升CAR-T细胞治疗的安全性。

AdCAR-T细胞技术所依赖的适配分子，体积微小，其分子量精确控制在约52千道尔顿。AdCAR-T通过持续输注的方式给药，其血浆半衰期约为30分钟，这一特性确保了药物在体内的有效浓度维持及适时清除。尤为重要的是，在遭遇更高级别的毒性反应时，我们能够迅速通过停止输注适配分子来干预，这一操作模式与某些生物特异性药物的给药策略相类似。

此策略不仅能够有效遏制毒性反应的进一步升级，而且有望实现副作用的中止与逆转，从而显著降低患者承受的风险。显然，这是AdCAR-T细胞技术相较于传统CAR-T疗法的一个显著且独特的优势，为急性髓系白血病患者提供了新的治疗希望与安全保障。

此外，若留意临床试验的进展，便会发现目前急性髓系白血病领域的多数靶抗原聚焦于CD33、CD123及CLL-1。正因如此，近90%的临床试验均围绕这些髓系抗原展开探索。这些抗原在治疗过程中会对健康造血系统产生预期的靶向毒性，故常被视作移植前的过渡性治疗手段。

相比之下，CD7作为一种靶抗原显得尤为独特，它并不在正常造血系统中表达，因此具有更高的特异性。值得注意的是，CD7在约30%的AML患者中呈阳性表达，并在《新英格兰医学杂志》上发表的相关研究中展示了令人瞩目的成果。在该研究中，患者接受了供体来源的CD7 CAR-T细胞治疗，并随后接受了异基因干细胞移植。这些患者在接受清淋治疗后，并未接受预处理或移植物抗宿主病的预防措施，这一治疗方法似乎极具潜力。

然而，我们也观察到CD7抗原丢失导致疾病复发的情况。因此，我认为我们可能需要采取多靶点策略，同时针对多个抗原进行治疗，以提高疗效。否则，我们将持续面临抗原逃逸这一难题，从而影响患者的治疗效果和预后。

What are the main advantages of Adapter CAR-T (AdCAR-T) technology in the treatment of acute myeloid leukemia (AML)? How does it overcome the limitations of traditional CAR-T therapy?

So what we have observed so far in CAR-T cell trials, in the context of AML, is a high incidence of severe cytokine release syndrome. Our approach using Adapter CAR-T (AdCAR-T) cells will increase the safety of CAR-T cells. These adapter molecules are small. They have a molecular weight of about 52 kilo Daltons. They are given as a continuous infusion, and their half-life is about 30 minutes.If you encounter higher-grade toxicity, you can stop the infusion of the adapter molecule, which is given as a continuous infusion similar to some of the bio-specifics, and thereby hopefully revert and stop the side effects.This is clearly one of the advantages of Adapter CAR-T (AdCAR-T) cells.

Currently, if you look at clinical government trials, most of the target antigens in the context of AML are CD33, CD123, and CLL-1. So, almost 90% of the clinical trials are following these myeloid lineage antigens. These have the expected on-target toxicity on the healthy hematopoietic system and are therefore mainly done as a bridge to transplant strategy. In contrast, CD7 is a more unique target antigen that is not expressed within the healthy hematopoietic system and is therefore more specific. It is expressed in about 30% of AML patients and has been presented and published in interesting data in the New England Journal of Medicine, where patients were treated with donor-derived CD7 CAR-T cells, followed by allogeneic stem cell transplantation. These patients accept lymphoid depletion did not really need conditioning or graft-versus-host prophylaxis. This seems to be a very interesting approach. However, what has also been seen is CD7 antigen loss and relapse. So, I think we probably need to target multiple antigens to be successful. Otherwise, we'll always see antigen escape.

Q2

AdCAR-T如何有效地针对AML细胞的异质性？这种策略在实际临床应用中的表现如何？

Marion Subklewe教授：在急性髓系白血病的生物学特性中，目标抗原的表达呈现出显著的异质性，这种异质性不仅体现在不同个体间的差异，还深刻影响着同一患者体内不同克隆间的表达模式。具体而言，即便是在同一位AML患者体内，针对同一目标抗原的不同克隆，其表达谱也往往大相径庭。这一特点与CD19 CAR-T细胞疗法所面对的情况形成了鲜明对比。

在我看来，若采用适配器方法治疗AML时，我们若仅将治疗焦点局限于单一抗原，则很可能无法实现疾病的根治。在此策略下，我们采用的是通用型CAR-T细胞，其特异性完全依赖于适配器分子的设计与选择。得益于这一设计，我们能够灵活地更换适配器，进而实现对多个抗原同时或依次地靶向。因此，我认为适配器平台的核心优势，在于其为我们提供了前所未有的能力，使我们能够针对AML中复杂多变的抗原表达谱，实施更为精准且全面的治疗策略。

How does AdCAR-T effectively target the heterogeneity of AML cells ? How has this strategy performed in actual clinical applications?

We know in AML that the target antigen expression is very heterogeneous, both inter- and intra-individuals. Even patients have different clones with different expression profiles of the same target antigen. So that's very different from the CD19 CAR-T cell field.

I don't believe we can cure AML by targeting only one antigen with the adapter approach, where we have a generic CAR-T cell. The specificity is only given by the adapter molecule. We can exchange the adapter and thereby target multiple antigens, either in parallel or sequentially. So I think the big advantage of the adapter platform is that we can target multiple antigens.

Q3

在优化急性髓系白血病的CAR-T细胞治疗策略方面，您认为需要全面审视并综合考量哪些关键因素？

Marion Subklewe教授：我认为，在优化急性髓系白血病的CAR-T细胞治疗策略时，必须全面审视并综合考量以下四个关键方面。首先，当前我们在患者已经历三到四种前期治疗，且前期治疗已相当充分的情况下，才考虑引入CAR-T细胞治疗。然而，我们应更积极地探索将双特异性CAR-T细胞及CAR-NK细胞应用于疾病负担较轻的更早期治疗阶段，以期获得更佳疗效。

其次，针对抗原逃逸变异体的存在，需要采取多抗原靶向策略。通过同时靶向两个或三个靶抗原，可以更有效地规避抗原逃逸现象，从而提高治疗的成功率。

第三，鉴于免疫抑制性微环境对CAR-T细胞治疗的影响，以及《自然医学》最新报道揭示的T细胞分泌细胞因子介导AML细胞抗性的机制，我们需要联合使用如JAK抑制剂等小分子药物，以克服这种抗性。

第四，探索与其他免疫策略的结合，如将CAR-T细胞治疗与STING激动剂等先天免疫激活剂联合应用，可能展现出广阔的前景。

此外，目前CAR-T细胞之外的治疗策略主要聚焦于两大领域。一方面，鉴于AML遗传学特征的异质性，我们正致力于研究各种遗传类型，并开发具有预后意义的靶向疗法。另一方面，微小残留病（MRD）的监测与管理同样至关重要，包括MRD的应答情况、持续存在状态以及再次转阳的风险。然而，在免疫治疗的背景下，特别是CAR-T细胞治疗的背景下，还必须将肿瘤微环境和骨髓状况作为重要的考量因素。随着不同风险亚组的出现，这一治疗策略将变得更加复杂。我担忧的是，如果根据遗传学、MRD和微环境对患者进行精细分层，每个组别的患者数量将非常有限。

因此，我认为传播和发展AML特异性CAR-T细胞的任务主要落在医学研究者的肩上。尽管患者数量有限，但我认为，正如肿瘤学其他领域一样，AML的治疗也必须采取个性化方法。一刀切的治疗策略在此类复杂疾病中注定无法取得成功。

In optimizing CAR-T cell therapy strategies for acute myeloid leukemia (AML), what key factors do you believe need to be comprehensively examined and considered?

I think four aspects have to be considered to improve CAR-T cells strategies, or therapy in AML. First of all, we are currently using CAR-T cells in heavily pretreated patients after three or four prior treatment lines. I think we have to move bio-specific CAR-T cells、CAR-NK cells into earlier treatment lines with low disease burden. Second, I think we need to integrate targeting of multiple antigens. We'll see antigen escape variants. So I think targeting two or three target antigens will be more successful. Thirdly, I think, as there is an immunosuppressive microenvironment and a recent report that also T cells secrete cytokines that mediate resistance of AML cells,that has been published in Nature Medicine, we also need to combine, for example, with JAK inhibitors or other small molecules to overcome resistance. And fourthly, other strategies like combining it with strategies of innate immunity like STING agonists could be really promising.

I think currently, our strategy, which is now independent of CAR-T cells, is very much focused on two aspects. The genetics of AML is very heterogeneous, and we have some targeted therapies, but it's also prognostic. So we are looking at all the different genetic types. The second really important aspect is MRD, so MRD response, MRD persistence, or turning MRD positive again.

But I think in the context of immunotherapy, particularly CAR-T cells, we have to integrate the tumor microenvironment, sort of the health of the bone marrow as a third factor. Unfortunately, it's gonna get more and more complicated with different small risk groups. I'm concerned that this will not be very attractive for industry, because we have really small patient population,if you stratify for genetics, MRD, and the microenvironment. So I think it's really the task of academic medicine to propagate and develop AML specific CAR-T cells. Unfortunately, but I think, like everywhere in oncology, this has to be a personalized approach, although the patient numbers will get really small. But I think one-size-fits-all concepts are not going to work.

Q4

能否谈谈您在研究过程中遇到的最大挑战是什么？以及您对未来研究方向的展望？

Marion Subklewe教授：当前，急性髓系白血病的治疗领域主要遵循两大策略。首要策略是运用CAR-T细胞疗法，旨在达成形态学上的白血病完全缓解状态，理想情况下实现MRD阴性，并随后辅以异基因干细胞移植。然而，该策略中CAR-T细胞需被完全清除，故而其疗效局限于一个相对短暂的时间窗口内。尽管如此，此方法仍能有效针对髓系抗原，且避免了造血功能衰竭的风险。

另一种极具潜力且持续发展的策略，则是基因编辑的干细胞移植。借助CRISPR/Cas技术，我们能够精准删除靶抗原，这包括整个靶抗原或是仅通过引入非同义突变来移除特定的被靶向表位，随后再引入CAR-T细胞治疗。此策略的一大优势在于，CAR-T细胞能够得以保留并持续发挥作用，从而展现出更持久的活性。因此，我们满怀期待地关注着这一方法未来的临床成效。值得注意的是，截至目前，关于第二种策略的临床试验数据尚未面世。

需要注意的是，当前领域内仍面临多重挑战。其中，核心难题之一在于寻觅恰当的靶抗原。当前，广泛采用的靶抗原多为髓系相关抗原，这一事实引发了我们对潜在风险的深切关注：这些抗原可能对健康造血系统产生靶向毒性，甚至诱发其他恶性肿瘤。尽管B细胞的缺失并不致命，且IgG缺乏症可通过IgG替代疗法得到有效管理，从而减轻了这一方面的顾虑，但在髓系细胞层面，情况则截然不同。因此，在AML治疗中精准识别并选定合适的靶抗原，构成了我们面临的一项严峻挑战。

此外，AML治疗还面临着另一项重大挑战，即耐药性的显著增强。AML的生物学特性使其更类似于具有免疫抑制性微环境的实体瘤，这无疑增加了治疗的复杂性和难度。其耐药性的产生，复杂地交织着微环境的调控作用以及T细胞与AML细胞间的相互作用。耐药性的存在要求我们不断探索新的治疗策略，以克服这一障碍。

鉴于此，我深信未来的治疗策略需更加多元化，可能需要引入其他小分子药物或设计更为精细的预处理方案，以期有效逆转免疫抑制性的微环境，从而为CAR-T细胞疗法创造更为有利的条件。同时，我也认为，单一依赖CAR-T细胞疗法难以达到理想的疗效，必须探索并实施联合治疗的策略，以协同增强治疗效果。因此，如何应对CAR-T细胞疗法在治疗AML中面临的耐药性挑战，无疑是摆在我们面前的一项重大而紧迫的任务。

could you share what the biggest challenge you faced during your research was? And what are your expectations for future research directions?

There are two strategies currently being followed in AML. One strategy is applying CAR-T cells, achieving a morphological leukemia-free state, preferentially MRD negative, and followed by an allogeneic stem cell transplantation.And with this approach, you eliminate all the CAR-T cells. You only have the efficacy of the CAR-T cells for a very limited approach.But at least you can target myeloid antigens. And aplasia is not an issue. I think a very interesting evolving strategy is to do edited stem cell grafts. You delete sort of the target antigen by CRISPR/Cas, either the entire target antigen or by creating a non-synonymous mutation, just the epitope that is targeted, followed by CAR-T cells. And there you have the advantage. The CAR-T cells are allowed to persist. They have longer activities. So we'll see how this turns out. And currently, we have no clinical trial data for the second approach yet.

One of the major challenges, in particularly in the context of acute myeloid leukemia, is identifying a suitable target antigen. As you are aware, most of the target antigens currently being employed are myeloid lineage antigens. There's a great concern of on-target of leukemia, toxicity on the healthy hemorrhagic system, as you're aware, and some malignancies. This is less of an issue because we can live without b cells and substitute IgG deficiency with IgG replacement therapy. So that is not the case with a myeloid compartment. Identifying suitable target antigen in AML is one of the challenges. The second challenge is that we have more resistance. It's more like a solid tumor with an immunosuppressive microenvironment. These are the two challenges we address in AML.

I think besides target antigens and toxicity, another big issue in CAR-T cells and AML is resistance, mediated through the microenvironment and through T-cell, AML interaction. I think future strategies have to implement possibly other small molecules or conditioning regimens to counteract the immunosuppressive microenvironment. I think we will not be able to cure with just a CAR-T cell therapy, but need to adopt combinatory approaches. So, I think this is one of the future challenges we have to tackle.

来源：肿瘤瞭望