2019-09-22 by Quick Biology Inc.
Glioblastoma multiforme (GBM) is the deadliest and most common type of malignant primary brain tumors in adults. Symptoms of GBM include seizure, nausea, headache, as well as progressive neurological and psychological deficit. Patients with GBM have a dismal prognosis: the median survival time after diagnosis is approximately 15 months, and the 5-year survival rate is only 4%.
Immunotherapy such as checkpoint blockade PD-1 or PD-L1 has led to remarkable regressions in liquid cancers (blood or bone marrow cancers), however, clinical trials showed these treatments do not give any better survival rate in GBM.
In recent Nature Biotechnology, researchers at Yale University developed a hybrid genetic screening system “AAV-SB-CRISPR”. In this system, Sleeping Beauty transposon and single-guide RNA cassette (for CRISPR-cas9 editing) are nested in and adeno-associated virus (AAV) (Fig.1). Using this hybrid vector, they screened surface proteome knockout library in primary T cells. By sequencing GBM-bearing mice after mutant CD8+ T-cell pool injection, researchers identified a few robust hits. Further independent models, especially mouse tumor models (Fig.2), demonstrated that pdia3 editing in T cells enhanced effector functions, which is more potent in the antigen-specific killing of human GBM cells.
Figure 1: Top, Schematics of hybrid AAV-SB-CRISPR vector; Bottom, schematics of in vivo AAV-SB-CRISPR screen in a syngeneic mouse model of GBM. (ref1)
Figure 2: Schematic of the preclinical therapeutic efficacy testing strategy for top candidates using different mouse models. (ref1)
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Reference:
- 1. Ye, L. et al. In vivo CRISPR screening in CD8 T cells with AAV–Sleeping Beauty hybrid vectors identifies membrane targets for improving immunotherapy for glioblastoma. Nat. Biotechnol. (2019). doi:10.1038/s41587-019-0246-4