Schedule Dependent Effects of Adoptively Transferred Autologous T Cells After AutoSCT for Myeloma: Accelerated Immune Recovery Is Associated with Improved Event-Free Survival

Abstract 784 BACKGROUND: Previously, we showed that adoptive transfer of in vivo vaccine-primed and ex vivo (anti-CD3/anti-CD28) costimulated autologous T cells (ex-T) at day +12 after transplant increased CD4 & CD8 levels at day +42 and augmented vaccine-specific immune responses in pts with myeloma (MM)[Nat Med 2005; 11: 1230-7]. DESIGN: We conducted a phase I/II 2-arm clinical trial in which 54 pts with advanced MM received autografts after high-dose melphalan followed by infusions of ex-T at day +2 after transplant. Pts also received pretransplant and posttransplant immunizations using a pneumococcal conjugate vaccine (PCV) only (ARM B; n = 26) or the PCV plus an HLA-A2 restricted multipeptide tumor antigen vaccine (3 hTERT peptides + 1 survivin peptide + 1 CMV peptide) for HLA-A2+ patients (ARM A; n = 28). After adoptive transfer of 4.26 × 10e10 costimulated T cells (range 1.59-5.0), the median CD3, CD4 and CD8 counts were 4198, 1545 and 2858 cells per microliter at day +14 post-transplant and 16% of pts developed significant autologous GVHD [Clin Cancer Res 2009;15: 4499 – 507]. Here we first report clinical outcomes from this trial and describe several novel observations about immune reconstitution after day +2 T-cell transfers. CLINICAL RESULTS: For the 54 total transplant pts, the median age was 55 (range 37-68), 28 (52%) were male and 21 (39%) were AA while 32 (59%) were Caucasian and 1 (2%) was Asian. 66% had IgG and 28% had IgA paraproteins while 6% excreted light chains only; 41% had abnormal cytogenetics. With a median followup of 1 year (0.25 - 2.5 years) 50 pts (93%) are alive and 31 (57%) remain event-free (EFS). The projected median EFS is 15 mos with no difference between ARMS A and B. Based on the Cox regression analysis, EFS did not correlate significantly to gender, race nor absolute lymphocyte counts (ALC). However, age correlated inversely to EFS with older pts exhibiting a lower EFS (coefficient = -0.0667, p-value = 0.0398). MM responses at day +60 and day +100 did not correlate to EFS, but the response at day +180 did correlate to EFS (p IMMUNOLOGICAL RESULTS: Preliminary results indicated that 6 of 15 pts (40%) in ARM A had positive tetramer responses to hTERT and/or survivin peptides at one or more timepoints after immunization, defined as tetramer staining by flow cytometry > 0.1% (and > 3-fold increase). Based on analysis of the first 36 patients, the mean sum of the antibody responses to 4 of the 7 serotypes of the pneumococcal conjugate vaccine (PCV; serotypes 6B, 14, 19F, 23F) were 83.55 mcg/ml at day +100 and 74.13 mcg/ml at day +180, highly protective levels, compared to 5.17 mcg/ml at enrollment. We also observed several novel features of immune system recovery after early T-cell transfers. Compared to an historical cohort of 103 MM pts who were autografted without ex-T, post-transplant quantitative IgG, IgA and IgM levels at day +180 (and days +60/+100 for IgG and IgA) were significantly higher in the pts who received day +2 T-cell transfers (IgG: 1525 mg/dl vs 1137 mg/dl, p= 0.014; IgA: 264 mg/dl vs 76 mg/dl, p = 0.0029; IgM: 58 mg/dl vs 39 mg/dl, p = 0.029). Furthermore, when IgG recovery was examined for the IgA MM pts only, the IgG level at day +180 was significantly higher in the ex-T trial (mean IgG = 810 mg/dl vs 611 mg/dl, p = 0.0478). Conversely, when IgA recovery was examined for the IgG MM pts only, the IgA level was significantly higher in the ex-T trial at days +60 (mean IgA = 129.82 mg/dl vs 71.70 mg/dl, p = 0.0036), day +100 (mean IgA = 114.43 mg/dl vs 59.44 mg/dl, p = 0.0075) and day +180 (mean IgA = 98.38 mg/dl vs 48.74 mg/dl, p = 0.0037). Remarkably, a pattern of CD8 T-cell “reprogramming” was also observed after day +2 T-cell transfers such that the % of CD8+/CD45RA+ T-cells at day +60 post-transplant was 75% vs 36% in a cohort of MM transplant pts who did not receive ex-T (p< 0.0001). In addition, the log ratio of Teffector/Tregulatory cells was significantly higher among the patients who received early T-cell transfers (2.57 vs. 1.93, p = 0.0066). CONCLUSIONS: Early adoptive transfers of anti-CD3/anti-CD28 costimulated autologous T-cells significantly enhanced post-transplant humoral and cellular immune reconstitution, a pattern which may be associated with better myeloma control and protection from infection. These data may have important implications for efforts to induce clinically significant immune responses to cancer vaccines in the transplant setting. Disclosures: Vonderheide: University of Pennsylvania and Dana Farber Cancer Institute: Patents & Royalties. June:University of Pennsylvania: Patents & Royalties.