Manufacturing outcomes for cGMP-grade gamma retroviral vectors for ex-vivo manufacturing of effector T cell therapies

Gene-modified effector T cell therapies such as CAR-T and TCR-T are manufactured ex-vivo with cGMP-grade viral vectors. However, global capacity for GMP-grade viral vector manufacturing is limited, with long wait times and high prices. The Israeli biotech industry and academic medical centers currently use overseas contract manufacturing organizations (CMOs) for GMP viral vector manufacturing. Here we describe manufacturing outcomes of 7 GMP grade gamma retroviral vectors manufactured at Sheba Medical Center over 2 years. All 7 vectors were successfully manufactured at 1 L scale. Physical and functional titers were measured with qualified assays. Functional titers measured via transduction of a qualified bank of primary human T cells were median 1.98e6 transducing units per mL (range 1.28e6-4.05e6). Physical titers measured via RT-qPCR were median 1.40e7 genome copies/mL (range 3.08e6-2.70e7). Transduction efficiency of primary human T cells with undiluted vector supernatant was median of 65% (range 40%-84%). The approach to QC testing of the vectors follows FDA and EMA guidance. Three of the vectors have passed all QC testing using a combination of qualified in-house analytic assays and validated assays performed by a contract testing laboratory. The remaining vectors will be tested and released as required to support upcoming IMPD submissions.