Insertional oncogenesis in 4 patients after retrovirus-mediated gene therapy of SCID-X1
Salima Hacein-Bey-Abina, … , Alain Fischer, Marina Cavazzana-Calvo
Salima Hacein-Bey-Abina, … , Alain Fischer, Marina Cavazzana-Calvo
Published August 7, 2008
Citation Information: J Clin Invest. 2008;118(9):3132-3142. https://doi.org/10.1172/JCI35700.
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Research Article

Insertional oncogenesis in 4 patients after retrovirus-mediated gene therapy of SCID-X1

Abstract

Previously, several individuals with X-linked SCID (SCID-X1) were treated by gene therapy to restore the missing IL-2 receptor γ (IL2RG) gene to CD34+ BM precursor cells using gammaretroviral vectors. While 9 of 10 patients were successfully treated, 4 of the 9 developed T cell leukemia 31–68 months after gene therapy. In 2 of these cases, blast cells contained activating vector insertions near the LIM domain–only 2 (LMO2) proto-oncogene. Here, we report data on the 2 most recent adverse events, which occurred in patients 7 and 10. In patient 10, blast cells contained an integrated vector near LMO2 and a second integrated vector near the proto-oncogene BMI1. In patient 7, blast cells contained an integrated vector near a third proto-oncogene,CCND2. Additional genetic abnormalities in the patients’ blast cells included chromosomal translocations, gain-of-function mutations activating NOTCH1, and copy number changes, including deletion of tumor suppressor gene CDKN2A, 6q interstitial losses, and SIL-TAL1 rearrangement. These findings functionally specify a genetic network that controls growth in T cell progenitors. Chemotherapy led to sustained remission in 3 of the 4 cases of T cell leukemia, but failed in the fourth. Successful chemotherapy was associated with restoration of polyclonal transduced T cell populations. As a result, the treated patients continued to benefit from therapeutic gene transfer.

Authors

Salima Hacein-Bey-Abina, Alexandrine Garrigue, Gary P. Wang, Jean Soulier, Annick Lim, Estelle Morillon, Emmanuelle Clappier, Laure Caccavelli, Eric Delabesse, Kheira Beldjord, Vahid Asnafi, Elizabeth MacIntyre, Liliane Dal Cortivo, Isabelle Radford, Nicole Brousse, François Sigaux, Despina Moshous, Julia Hauer, Arndt Borkhardt, Bernd H. Belohradsky, Uwe Wintergerst, Maria C. Velez, Lily Leiva, Ricardo Sorensen, Nicolas Wulffraat, Stéphane Blanche, Frederic D. Bushman, Alain Fischer, Marina Cavazzana-Calvo

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Figure 4

Longitudinal analysis of vector integration sites in P7 and P10.

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Longitudinal analysis of vector integration sites in P7 and P10. (A and ...
(A and D) DNA samples from patient cells were digested with restriction enzymes and ligated to linkers, after which integration site sequences were determined by PCR amplification and pyrosequencing. Numbers above bars denote total integration site reads, with composition broken down. PBL, peripheral blood lymphocytes. Longitudinal analysis of samples from P7 (A) and P10 (D). Time of chemotherapy is indicated by the arrow. (B and E) Analysis of genomic DNA samples by ligation-mediated PCR, separation by electrophoresis on an agarose gel, and staining with ethidium bromide. (B) In P7, the intense band in the M+68 sample had the mobility expected for the CCND2 amplification product. (E) In P10, bands of the expected sizes were observed for the LMO2 and BMI1 amplification products in the M+33 sample. (C and F) Longitudinal vector copy number analysis. Quantitative real-time PCR analysis of PBMC DNA from P7 and P10 obtained at the indicated times after gene therapy. (C) P7 showed 1 integrated copy in the leukemic blasts at M+68, concordant with the unique detected integration site. (F) In P10, 2 integrated copies at M+33 were detected, contrasting with the 1 copy detected before and after chemotherapy. These data confirmed that there is 1 leukemic clone bearing the 2 proviral integration sites, LMO2 and BMI1. (G–L) Number of integration sites shared (pink, yellow, and orange) versus not shared (gray) at the indicated time points for P7 (G–I) and P10 (J–L).