Mucin 1-specific active cancer immunotherapy with tecemotide (L-BLP25) in patients with multiple myeloma: an exploratory study

Abstract

Patients (n = 34) with previously untreated, slowly progressive asymptomatic stage I/II multiple myeloma or with stage II/III multiple myeloma in stable response/plateau phase following conventional anti-tumor therapy were immunized repeatedly with the antigen-specific cancer immunotherapeutic agent tecemotide (L-BLP25). Additionally, patients were randomly allocated to either single or multiple low doses of cyclophosphamide to inhibit regulatory T cells (Treg). Immunization with tecemotide resulted in the induction/augmentation of a mucin 1-specific immune response in 47% of patients. The immune responses appeared to involve a Th1-like cellular immune response involving CD4 and CD8 T cells. The rate of immune responses was similar with single versus multiple dosing of cyclophosphamide and in patients with vs. without pre-existing mucin 1 immunity. On-treatment reductions in the slope of M-protein concentration over time (but not fulfilling clinical criteria for responses with conventional anti-tumor agents) were observed in 45% of evaluable patients, predominantly in those without versus with pre-existing mucin 1 immunity and in patients with early stage disease. No differences were seen in patients receiving single or multiple cyclophosphamide dosing. Treatment with tecemotide was generally well tolerated. Repeated vs. single dosing of cyclophosphamide had no impact on Treg numbers and was stopped after a case of fatal encephalitis that was assessed as possibly study-related. Tecemotide immunotherapy induces mucin 1-specific cellular immune responses in a substantial proportion of patients, with preliminary evidence of changes in the M-protein concentration time curve in a subset of patients.

Trial registration: ClinicalTrials.gov NCT01094548.

Keywords: ASCI, antigen-specific cancer immunotherapy; AUC, area under the curve; Cy, cyclophosphamide; ELISpot, enzyme-linked immunosorbent spot; GM-CSF, granulocyte-macrophage colony-stimulating factor; HR, hazard ratio; IDA, Immunologic Diagnostic Analysis; IFN-g, interferon-g; IL-17, interleukin-17; IQR, interquartile range; L-BLP25; MM, multiple myeloma; MUC1; MUC1, mucin 1; NSCLC, non-small cell lung cancer; PBMC, peripheral blood mononuclear cell; TNF-α, tumor necrosis factor-α; Treg, regulatory T cell; URR, upper reference range; immunotherapy; mucin 1; multiple myeloma; tecemotide.

Figures

Figure 1.

CONSORT flow diagram for enrolment and treatment of patients. Cy: cyclophosphamide; d: day; IV: intravenous; SC: subcutaneous; Wk: week. *Patients who received at least one dose of study treatment; †Patients with at least one complete set of baseline, week 5 and week 9 data of either ELISpot, proliferation or cytokine assay.

Figure 2.

Baseline MUC1 immune responsiveness and on-treatment induction of MUC1-specific immune responses. (A) Group A: tecemotide with single Cy dosing and (B) Group B: tecemotide with repeated Cy dosing. Baseline MUC1-specific immune response () defined as a ≥2-fold increase over no peptide control in at least one assay at baseline. On-treatment assessment time points at which there was a ≥2-fold increase over baseline and no peptide control are highlighted () for each patient and assay (ELISPOT, proliferation and FACS). Immune responses were assessed following stimulation with the MUC1-derived peptides BP25, MUC A2 or MUC A22 A11, and values in the shaded boxes indicate the number of antigens for which there was a ≥2-fold increase for each assay and time point. On-treatment responses were defined as a ≥2-fold increase over baseline and no peptide control in at least one of the assays (overall immune response, ) on at least 2 occasions while on study treatment. Cy: cyclophosphamide; ELIS: enzyme-linked immunosorbent spot (ELISpot); FACS: fluorescence-activated cell sorting; PROL: proliferation. Pt: patient.

Figure 3.

Median normalized AUC values for T cell subsets in blood. Comparison of median normalized AUC values of percentages and absolute counts for (A) Treg cells in Groups A and B; and, (B) naïve, effector and memory CD4+ and CD8+ T cells for patients with and without an immune response. Bars = interquartile range. AUC: area under the curve. *Mann-Whitney U-test testing similarity of distribution of AUC values regarding treatment arms. †n = 14.

Figure 4.

Immunotherapy-induced production of non-disease-related cytokines by PBMC. Cytokine production determined by Luminex® assay following in vitro stimulation of PBMC with MUC1-derived peptides (BP25, MUC-A2 and MUC-A22-A11). Induction () or no induction () of IFN-γ, GM-CSF, TNF-α and IL-17 production (≥50% increase on one occasion) as well as overall immune response (≥2-fold on 2 occasions, see supplementary data Appendix S3) for patients in the Immunologic Diagnostic Analysis Set. n/e = not evaluable. Cy: cyclophosphamide; GM-CSF: granulocyte-macrophage colony-stimulating factor; IFN-γ: interferon-γ; IL-17: interleukin-17; TNF-α: tumor necrosis factor-α.

Figure 5.

M-protein concentration changes. (A) Comparison of the slope of M-protein changes over time before and during study treatment. Negative M-protein slope/decrease (); Positive M-protein slope/increase (); On-treatment reduction in M-protein slope* / Overall induced MUC1-specific immune response (). (B) On treatment changes in M-protein concentration over time (AUC26) according to the presence or absence of a spontaneous, pre-treatment or induced, on-treatment MUC1-specific immune response. Values are medians, with Q1-Q3 interquartile ranges (boxes) and minimum-maximum ranges (bars). P-value are from Mann-Whitney U-test testing similarity of AUC value distributions between groups. MM: multiple myeloma; MUC1: mucin 1. *Difference in M-protein slope post- versus pre-baseline <0; analysis excludes patients with <5 pre- or <5 post-baseline values; analyzed with 2 separate linear regression models on pre- and post- baseline values for each patient vs. treatment day, including intercept, “slope” refers to value of regression coefficient of slope parameter.