Implementing preclinical study findings to protocol design: translational studies with alloreactive CTL for gliomas.

ABSTRACT

We are accruing patients to a Phase I dose escalation cellular therapy trial (www.clinicaltrials.gov, NCT01144247) involving intratumoral placement of alloreactive cytotoxic T lymphocytes (alloCTL) for recurrent gliomas. The trial is being conducted to confirm the findings of a prior pilot study that indicated this adjuvant therapy may be beneficial in extending survival of recurrent WHO grade III gliomas. To reduce costs of the cellular therapy, we tested a number of synthetic tissue culture media and found the AIM-V growth medium superior for their growth. We also moved the production of the alloCTL from artificial capillary systems to less expensive tissue culture bags. To standardize alloCTL infusates used for therapy, release criteria of ≥60% CD3+ and ≥60% viability were established that consistently translated to a 4 hr cytotoxicity of ≥30% at a 301 effector to target ratio. To allow time for completion of quality control testing and transport to the infusion site, we determined that 30,000 IU of human recombinant Interleukin-2 in the cellular infusates sufficiently retained cell viability and cytotoxicity to allow a 10 hr expiration time to be placed on the infusates. We identified a cytotoxic T cell subset, CD3+/CD8+/CD69+, that demonstrated upregulated IFN-γ production upon exposure to relevant target cells. The phenotypic identification of this T cell subset was indicative of robust in vitro cytotoxic function and thus will be followed to determine if it correlates with patient immune response to treatment. Finally, other therapeutic agents routinely used for glioma treatment were integrated into an analysis of alloCTL cytotoxic functionality. Temozolomide and bevacizumab do not adversely affect cytotoxic function of the alloCTL in the short-term, thus providing rationale for further investigating combinatorial chemo-immunotherapy for gliomas.