Quantitative shearing linear amplification polymerase chain reaction: an improved method for quantifying lentiviral...

Area of Science:

• Biotechnology
• Molecular Biology
• Hematology

Background:

• Gene therapy for blood disorders relies on monitoring hematopoietic stem cell (HSC) clones.
• Vector insertion site (VIS) effects can lead to undesirable clonal dominance.
• Existing VIS analysis methods lack precise quantitative accuracy for early detection.

Purpose of the Study:

• To develop a rapid, inexpensive, and quantitative assay for measuring clone size in gene therapy.
• To accurately detect early clonal dominance arising from vector insertion sites.
• To assess clonal repertoires in HSC gene therapy trials.

Main Methods:

• Developed quantitative shearing linear amplification PCR (qsLAM PCR) assay.
• Utilizes random genomic DNA shearing, minimal exponential PCR amplification, and shear site counts.
• Incorporates an internal control with known lentiviral insertion sites per cell.

Main Results:

• qsLAM PCR provided controlled and quantitative results in both animal models and human clinical samples.
• Successfully detected early clonal dominance in a macaque transplanted with limited transduced HSCs.
• Clinical samples from an X-linked severe combined immunodeficiency (XSCID) trial participant showed diverse clonal representation.

Conclusions:

• qsLAM PCR is a facile and quantitative assay for measuring clonal repertoires.
• The assay is suitable for subjects in human gene therapy trials using lentiviral-transduced HSCs.
• Enables accurate monitoring of clonal dynamics in gene therapy applications.