In vivo inducible reverse genetics in patients' tumors to identify individual therapeutic targets

Nat Commun. 2021 Sep 27;12(1):5655. doi: 10.1038/s41467-021-25963-z.


High-throughput sequencing describes multiple alterations in individual tumors, but their functional relevance is often unclear. Clinic-close, individualized molecular model systems are required for functional validation and to identify therapeutic targets of high significance for each patient. Here, we establish a Cre-ERT2-loxP (causes recombination, estrogen receptor mutant T2, locus of X-over P1) based inducible RNAi- (ribonucleic acid interference) mediated gene silencing system in patient-derived xenograft (PDX) models of acute leukemias in vivo. Mimicking anti-cancer therapy in patients, gene inhibition is initiated in mice harboring orthotopic tumors. In fluorochrome guided, competitive in vivo trials, silencing of the apoptosis regulator MCL1 (myeloid cell leukemia sequence 1) correlates to pharmacological MCL1 inhibition in patients´ tumors, demonstrating the ability of the method to detect therapeutic vulnerabilities. The technique identifies a major tumor-maintaining potency of the MLL-AF4 (mixed lineage leukemia, ALL1-fused gene from chromosome 4) fusion, restricted to samples carrying the translocation. DUX4 (double homeobox 4) plays an essential role in patients' leukemias carrying the recently described DUX4-IGH (immunoglobulin heavy chain) translocation, while the downstream mediator DDIT4L (DNA-damage-inducible transcript 4 like) is identified as therapeutic vulnerability. By individualizing functional genomics in established tumors in vivo, our technique decisively complements the value chain of precision oncology. Being broadly applicable to tumors of all kinds, it will considerably reinforce personalizing anti-cancer treatment in the future.

Publication types

  • Observational Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Signal Transducing / antagonists & inhibitors
  • Adaptor Proteins, Signal Transducing / genetics
  • Adult
  • Animals
  • Antineoplastic Agents / pharmacology*
  • Antineoplastic Agents / therapeutic use
  • Biomarkers, Tumor / antagonists & inhibitors
  • Biomarkers, Tumor / genetics*
  • Child
  • Female
  • Gene Silencing
  • Homeodomain Proteins / antagonists & inhibitors
  • Homeodomain Proteins / genetics
  • Humans
  • Leukemia, Myeloid, Acute / drug therapy*
  • Leukemia, Myeloid, Acute / genetics
  • Male
  • Mice
  • Myeloid Cell Leukemia Sequence 1 Protein / antagonists & inhibitors
  • Myeloid Cell Leukemia Sequence 1 Protein / genetics
  • Myeloid-Lymphoid Leukemia Protein / antagonists & inhibitors
  • Myeloid-Lymphoid Leukemia Protein / genetics
  • Oncogene Proteins, Fusion / antagonists & inhibitors
  • Oncogene Proteins, Fusion / genetics
  • Precision Medicine / methods
  • Precursor Cell Lymphoblastic Leukemia-Lymphoma / drug therapy*
  • Precursor Cell Lymphoblastic Leukemia-Lymphoma / genetics
  • Reverse Genetics / methods*
  • Xenograft Model Antitumor Assays


  • Adaptor Proteins, Signal Transducing
  • Antineoplastic Agents
  • Biomarkers, Tumor
  • DDIT4L protein, human
  • DUX4L1 protein, human
  • Homeodomain Proteins
  • MCL1 protein, human
  • MLL-AF4 fusion protein, human
  • Myeloid Cell Leukemia Sequence 1 Protein
  • Oncogene Proteins, Fusion
  • Myeloid-Lymphoid Leukemia Protein