Myeloma remains largely incurable in spite of high-dose chemotherapy and autologous stem cell transplantation (ASCT) and targeted therapies. Retrospective studies suggest that better clinical outcomes may be associated with more rapid lymphocyte recovery during the early post-transplant period. In addition, tumor-reactive T-cells are present at low frequencies in the marrow or blood of untreated patients with myeloma. Thus, strategies to augment the recovery and function of autologous T-cells post-transplant may be clinically beneficial. Furthermore, they have the potential to synergize with current therapies to promote remissions and achieve long term disease free survival. We have conducted several trials of adoptive transfer T cell therapy for multiple myeloma, testing the hypothesis that improved T-cell recovery through intravenous infusion of ex-vivo CD28 costimulated T cells might provide a platform for post-transplant immunotherapy and enhance vaccine strategies. Autologous T-cells were stimulated by artificial antigen presenting cells under conditions that promote central memory cells and Th1/Tc1 function. In the first study, a 7-valent pneumococcal conjugate vaccine (PCV) was used as a well-defined antigen which allowed us to show that the adoptive transfer of in-vivo vaccine-primed and ex-vivo costimulated autologous T-cells early after transplant led to enhanced T-cell recovery and generated vaccine-specific T and B-cell responses. In the second study, this platform of combined vaccine and T-cell immunotherapy also generated immune responses in a significant proportion of patients against a putative tumor antigen vaccine composed of peptides derived from human telomerase (hTERT) and survivin. Currently, we are studying whether the frequency and magnitude of the myeloma-directed immune responses can be enhanced by using a different vaccine based on MAGE-A3 and a novel vaccine adjuvant called Poly-ICLC (a TLR-3 receptor agonist). However, there are at least two potential drawbacks of the approach that we have taken so far: i) the adoptively transferred T-cells are polyclonal and thus only a small proportion are truly directed against the myeloma tumor cells;and ii) the myeloma specificity depends on successful "priming" of the autologous T-cells prior to collection and costimulation/expansion, a process that is inefficient especially in the setting of active malignancy. To address these impediments to effective immunotherapy in this proposal, we will genetically modify autologous T-cells through transduction of lentiviral constructs which encode high-affinity T-cell receptors (TCRs) for two naturally processed epitopes that are derived from tumor antigens MAGE-A3 and NY-ESO-1. These cancer/testis tumor antigens (CTAgs) are frequently and specifically expressed in myeloma cells. We will specifically study whether these transduced cells can be safely transferred very soon after autologous stem cell transplantation (ASCT) and whether these gene-modified T-cells persist, function and target myeloma cells in patients. We will also use lenalidomide both as a post-transplant maintenance treatment for myeloma and as a possible immunomodulator. Recent work indicates that lenalidomide may have important immunostimulatory properties. If this study shows that TCR-gene modified T-cells are safe and functional then this combination strategy of ASCT followed by adoptive transfer of "redirected" autologous T-cells could be a platform for effective post-transplant immunotherapy of myeloma and perhaps other hematologic neoplasms.
Our long-term goal is to develop a strategy for generating clinically effective immune responses against myeloma in order to potentially increase the likelihood of long-term remission and cure. Our hypothesis is that adoptive transfer of expanded/activated autologous T cells that are genetically redirected toward myeloma tumor targets will be safe and may result in significant anti-tumor immunity after autologous stem cell transplantation for myeloma. The current proposal is based on our fourth major clinical trial in the area of post-transplant adoptive T-cell therapy.
|Linette, Gerald P; Stadtmauer, Edward A; Maus, Marcela V et al. (2013) Cardiovascular toxicity and titin cross-reactivity of affinity-enhanced T cells in myeloma and melanoma. Blood 122:863-71|