Introduction
The recMAGE-A3 protein has been administered intramuscularly (IM) with immunostimulant
AS15 as an experimental immunotherapeutic. AS15 contains 3-O-desacyl-4'-monophosphoryl
lipid A (MPL), QS-21, CpG 7909 and liposome. This MAGE-A3/AS15 immunotherapeutic has
not been studied for intradermal (ID) or subcutaneous (SC) use. A clinical trial (NCT01425749)
was initiated to test the hypotheses that ID/SQ administration is safe and may induce
CD4+ and CD8+ T cell responses to MAGE-A3.
Patients and methods
Twenty-five eligible patients with resected stage IIB-IV MAGE-A3+ melanoma were randomized
to 2 arms, treated with MAGE-A3/AS15 Immunotherapeutic IM (Arm A, n = 13) or ID/SC
(Arm B, n = 12). Adverse events (CTCAE 4) were recorded. Antibody (Ab) responses to
MAGE-A3 protein were assessed by ELISA assay. T cell responses were assessed by flow
cytometry after intracellular cytokine staining (ICS) for multifunctional CD4+ and
CD8+ responses to overlapping MAGE-A3 peptides, assaying lymphocytes from peripheral
blood (PBMC) and sentinel immunized node (SIN), after one in vitro stimulation.
Results
In both arms, the recMAGE-A3/AS15 immunotherapeutic was well-tolerated, with only
one grade 3 treatment-related adverse event (hyperglycemia, Arm B), and no grade 4
or 5 events. Grade 2 injection site reactions were observed in 10 patients in Arm
A and 7 in Arm B (P > 0.3). Ab responses were detected in all patients, most with
high titers persisting at least 6 months, without difference between arms. Preliminary
T cell data are that multifunctional (IFNg and TNFα) CD4+ T cell responses to MAGE-A3
were detected in 64% of patients (54% A; 75% B; Table 1). Multifunctional CD8+ T cell
responses were evident in 20% of patients (8% A, 33% B). CD4+ responses were higher
magnitude in SIN than in PBMC.
Table 1
Multifunctional (IFNg and TNFα) T cell responses to MAGE-A3
% of CD4+ T cells
% of CD8+ T cells
(90% CI)
(90% CI)
SIN
PBMC
Either
SIN
PBMC
Either
Arm A
31%
31%
54%
0%
8%
8%
(11, 58)
(11, 58)
(29, 78)
(0, 21)
(0, 32)
(0, 32)
Arm B
64%
50%
75%
18%
25%
33%
(35, 86)
(25, 75)
(47, 93)
(3, 47)
(7, 53)
(12, 61)
Total
46%
40%
64%
8%
16%
20%
(28, 64)
(24, 58)
(46, 80)
(2, 24)
(6, 33)
(8, 38)
Conclusion
Safety profiles were comparable for ID/SC and IM administration of the MAGE-A3/AS15
immunotherapeutic, which induced high-titer Ab, multifunctional CD4+ Th1 responses,
and CD8+ responses when administered by either route. Immune responses were more readily
detected in the SIN than in PBMC. These pilot data support further investigation of
ID/SC immunization with antigen plus AS15 to support Th1 CD4+ responses and CD8+ responses.
Production of Th1 cytokines IFNg and TNFα suggests the induced CD4+ responses may
support CD8+ T cells. Other forms of antigen (e.g.: long peptides) may further support
induction of CD8+ T cell responses in combination with AS15.
Funding source: GlaxoSmithKline Biologicals SA