Gene Transfer into Humans — Immunotherapy of Patients with Advanced Melanoma, Using Tumor-Infiltrating Lymphocytes Modified by Retroviral Gene Transduction

TLDR

Treatment with tumor‑infiltrating lymphocytes plus interleukin‑2 can induce regression of metastatic melanoma in about half of patients. The study aimed to optimize TIL therapy and monitor its in‑vivo distribution by retrovirally inserting a neomycin‑resistance gene into TIL before infusing them into five patients. Retroviral transduction of TIL with the neomycin‑resistance gene was performed, and gene presence and expression were confirmed by Southern blot, enzymatic assay, and PCR, enabling tracking of the modified cells. All five patients tolerated the treatment without adverse effects, and the gene‑modified TIL persisted in circulation for up to two months, were recovered from tumor deposits up to 64 days after infusion, and grew in high concentrations of G418, demonstrating the safety and feasibility of this approach.

Abstract

Treatment with tumor-infiltrating lymphocytes (TIL) plus interleukin-2 can mediate the regression of metastatic melanoma in approximately half of patients. To optimize this treatment approach and define the in vivo distribution and survival of TIL, we used retroviral-mediated gene transduction to introduce the gene coding for resistance to neomycin into human TIL before their infusion into patients--thus using the new gene as a marker for the infused cells.Five patients received the gene-modified TIL. All the patients tolerated the treatment well, and no side effects due to the gene transduction were noted. The presence and expression of the neomycin-resistance gene were demonstrated in TIL from all the patients with Southern blot analysis and enzymatic assay for the neomycin phosphotransferase coded by the bacterial gene. Cells from four of the five patients grew successfully in high concentrations of G418, a neomycin analogue otherwise toxic to eukaryotic cells. With polymerase-chain-reaction analysis, gene-modified cells were consistently found in the circulation of all five patients for three weeks and for as long as two months in two patients. Cells were recovered from tumor deposits as much as 64 days after cell administration. The procedure was safe according to all criteria, including the absence of infections virus in TIL and in the patients.These studies demonstrate the feasibility and safety of using retroviral gene transduction for human gene therapy and have implications for the design of TIL with improved antitumor potency, as well as for the possible use of lymphocytes for the gene therapy of other diseases.