Targeting CD70 with iPSC-Derived CAR-NK Cell Therapy

Background and Objectives of the Study

Over the past decade, cellular therapy for cancer has revolutionized traditional treatment concepts by introducing the idea of a “living drug.” In particular, chimeric antigen receptor T cell (CAR-T) therapy has drastically improved the efficacy of immunotherapy, offering a potentially curative option for hematological malignancies that were previously considered incurable. However, CAR-T therapy faces several limitations, including the restricted targeting range, time-consuming and costly production processes, and the risk of manufacturing failures. These challenges hinder its broad application in cancer patients who require rapid intervention.

To address these issues, CD70 has emerged as an important immunological checkpoint molecule due to its high expression in a wide range of hematological and solid tumors. CD70-targeted therapies, such as monoclonal antibodies, antibody-drug conjugates, and CD70 CAR-T cells, have demonstrated promising efficacy in conditions like acute myeloid leukemia, lymphoma, and renal cancer. Furthermore, the innate anti-cancer mechanisms of natural killer (NK) cells provide a new platform for expanding immune cell therapy against various cancer types. However, the intrinsic antitumor function of NK cells is often impaired by the downregulation of NCR/NKG2D ligands on tumor cells, allowing certain cancers to evade treatment.

To overcome these limitations, Wang et al. proposed developing a universal iPSC (induced pluripotent stem cell)-derived CD70-targeted CAR-NK cell (70CAR-iNK) therapy. This study explores a novel approach for next-generation immunotherapy aimed at universal cancer treatment and minimizing rejection by alloreactive T cells.

Study Citation and Author Team

This research was jointly conducted by the Zhejiang University School of Medicine, Zhejiang Engineering Research Center for Stem Cell and Immunity Therapy, and Qihan Biotech. The study was led by Linqin Wang, Yiyun Wang, Xiangjun He, among others. The research paper was published on January 21, 2025, in Cell Reports Medicine, Volume 6, Article 101889.

Research Design and Methodology Overview

This study involved a multi-phase experimental workflow, ranging from gene editing to functional evaluation in vitro and in vivo:

1. CD70-Targeted Gene Editing and Generation of iPSC-Derived NK Cells

The research team employed CRISPR-Cas9 technology for multi-gene editing of iPSCs, with specific functional modifications including:

• Knockout of the CD70 Gene (CD70-KO): This prevents fratricide (mutual killing among NK cells) caused by CD70 expression. Further testing verified that CD70-KO did not impair the differentiation potential or functionality of iNK cells.
• Introduction of High-Affinity, Non-Cleavable CD16 (hnCD16): This enhances antibody-dependent cellular cytotoxicity (ADCC).
• Integration of IL-15 Receptor Alpha/IL-15 Fusion Protein (IL15RF): This improves cell persistence and proliferation.
• Expression of CD70-Targeted CAR Molecules: This enhances tumor detection and killing efficiency.

Using an optimized differentiation platform, the modified iPSCs successfully differentiated into high-purity, functional iNK cells. Phenotypic correction and functional validation confirmed that the cells expressed mature markers such as CD56, NKG2D, and NKp46.

2. Analysis of CD70 Expression Across Tumor Types

The study analyzed transcriptomic data from the TCGA database for 33 cancer types. CD70 expression was found to be significantly elevated in 14 cancer types, including renal cancer, diffuse large B-cell lymphoma (DLBCL), and mesothelioma, compared to adjacent normal tissues. Additionally, data from the Human Protein Atlas validated that CD70 is broadly expressed across lymphoma subtypes, especially in virus-infected lymphomas and relapsed/refractory DLBCL.

3. In Vitro Cytotoxicity Assessment

Using hematological and solid tumor cell lines (e.g., Raji, MT-4, HeLa, and SKOV-3) as targets, 70CAR-iNK cells demonstrated significant antitumor capabilities. CAR expression played a critical role in enhancing cytotoxic effects, particularly in cancer cells with low NCR/NKG2D ligand expression.

Moreover, in CD70-KO Raji cells, the study further validated ADCC enhancement through Rituximab (an anti-CD20 antibody). It was confirmed that hnCD16’s non-cleavable property stabilized effector functions.

4. In Vivo Antitumor and Persistence Evaluation

In murine xenograft models (e.g., lymphoma MT-4 and renal cancer Caki-1), 70CAR-iNK cells significantly inhibited tumor growth and prolonged survival compared to unmodified iNK cells. Cells expressing IL15RF exhibited superior in vivo persistence and proliferation.

5. Suppression of Alloreactive T Cell Responses

An allorejection model demonstrated that 70CAR-iNK cells effectively depleted CD70-expressing activated alloreactive T cells, significantly reducing the expression of activation markers (e.g., CD69, CD137) and consequently mitigating allorejection.

Study Conclusions and Significance

The study validated that 70CAR-iNK cells possess strong antitumor potential, effectively targeting a broad spectrum of cancer types while also eliminating alloreactive T cells to enhance NK cell persistence. This research provides theoretical support for universal immune cell therapy platforms and paves the way for personalized treatment and large-scale industrial production.

Clinical and Scientific Value

1. Scientific Value: The study is a pioneer in integrating multi-gene editing technologies to address fratricide and enhance functionality, marking a new chapter in CD70-targeted NK therapy.
2. Application Value: As a universal immune cell product, 70CAR-iNK cells reduce costs and accelerate production cycles while broadening the patient population that can benefit from treatment.

Research Highlights

• Innovation in Multi-Gene Editing: The integration of CAR modules, IL15RF, and hnCD16 achieved comprehensive functional enhancements.
• Broad Tumor Target Coverage: The approach targets CD70-expressing tumors, addressing gaps in current clinical therapies.
• Mitigation of Allorejection: The CD70-targeted strategy reduces graft-vs-host disease (GVHD) risk, laying the groundwork for universal immunotherapy.

Through this report, Wang et al. highlight the potential of genetic engineering and cellular innovation to propel the development of next-generation immunotherapies, heralding new hope for the future of cancer treatment.