Peptide vaccination elicits leukemia-associated antigen-specific cytotoxic CD8+ T-cell responses in patients with chronic lymphocytic leukemia

Abstract

The receptor for hyaluronic acid-mediated motility (RHAMM) is a tumor-associated antigen in chronic lymphocytic leukemia (CLL). CD8 þ T cells primed with the RHAMM-derived epitope R3, which is restricted by human leukocyte antigen (HLA)-A2, effectively lyse RHAMM þ CLL cells. Therefore, we initiated a phase I clinical trial of R3 peptide vaccination. Six HLA-A2 þ CLL patients were vaccinated four times at biweekly intervals with the R3 peptide (ILSLELMKL; 300 lg per dose) emulsified in incomplete Freund's adjuvant; granulocyte-macrophage colony stimulating factor (100 lg per dose) was administered concomitantly. Detailed immunological analyses were conducted throughout the course of peptide vaccination. No severe adverse events greater than CTC I1 skin toxicity were observed. Four patients exhibited reduced white blood cell counts during vaccination. In five of six patients, R3-specific CD8 þ T cells were detected with the corresponding peptide/HLA-A2 tetrameric complex; these populations were verified functionally in four of five patients using enzyme-linked immunosorbent spot (ELISpot) assays. In patients with clinical responses, we found increased frequencies of R3-specific CD8 þ T cells that expressed high levels of CD107a and produced both interferon-c and granzyme B in response to antigen challenge. Interestingly, vaccination was also associated with the induction of regulatory T cells in four patients. Thus peptide vaccination in six CLL patients was safe and could elicit to some extent specific CD8 þ T-cell responses against the tumor antigen RHAMM.

Functional invariant natural killer T-cell and CD1d axis in chronic lymphocytic leukemia: implications for immunotherapy

“…[4][5][6][7] The mechanism of this adjuvant activity involves presentation of α-GalCer to iNKT cells by resident dendritic cells (DC), 8 DC maturation, 4 and enhanced DC production of interleukin-12. 9 Chronic lymphocytic leukemia (CLL) represents an attractive target for cellular immunotherapy: a graft-versusleukemia effect can be observed after allogeneic stem cell transplantation, 10 peptide vaccination can induce leukemiaspecific cytotoxic T cells, 11 and remission can be induced using autologous T cells bearing a chimeric antigen receptor directed against CD19. 12 However, significant immunological defects have been documented in patients with CLL, which may disrupt immunotherapeutic approaches.…”

Peptide vaccination induces profound changes in the immune system in patients with B-cell chronic lymphocytic leukemia

“…Changes in Treg frequencies, peptide-specific cytotoxic T cells (tetra/CD8) as well as analysis of activation markers were discussed in our previous report [12]. For the present study, we focused on the following subpopulations: CD8 Table 1A), while more dynamic changes in Th17 cell levels were observed in Patient#2 ( Figure 1B, Table 1B) who did not respond to therapy.…”

“…In contrast, higher initial frequencies of CD8 + CD137 + T cells in Patients#3 and #4 declined after the first vaccination and then increased substantially after the third dose of the vaccine (Table 1, panels C and D respectively). Although both patients responded hematologically, Patient#4 did not respond immunologically according to our definitions [12] and Patient#5 was discordant with respect to R3-tetra staining and the release of IFN-g in ELISpot assays. Interestingly, CD8…”

“…We further found association of antigen RHAMM expression with proliferation potential (defined by Ki-67 expression in lymph nodes) as well as functional dependence on CD40-CD40L pathway, which seems to play an important role in the pathogenesis of CLL [11]. Most recently, we completed the first vaccination trial with the peptide R3 which represented the most immunologic epitope of antigen RHAMM in CLL patients [12]. Vaccination proved to be feasible, safe, and able to induce immune responses, in six vaccinated patients.…”

“…Molecular genetics characterization, including the detection of genomic aberrations by fluoresence-in-situ-hybridization (FISH), were performed as previously described [20]. Detailed patient characteristics have previously been published [12].…”