E-poster Presentation 2014 World Cancer Congress

Phase I trial of a cancer vaccine consisting of 20 mixed peptides in patients with castration-resistant prostate cancer: dose-related immune boosting and suppression (#925)

Masanori Noguchi 1 , Gaku Arai 2 , Kazumasa Matsumoto 3 , Seiji Naito 4 , Fukuko Moriya 1 , Shigetaka Suekane 1 , Nobukazu Komatsu 1 , Satoko Matsueda 1 , Tetsuro Sasada 1 , Akira Yamada 1 , Kyogo Itoh
  1. Kurume University School of Medicine, Kurume, Japan
  2. Dokkyo Medical University Koshigaya Hospital, Koshigaya
  3. Kitasato University School of Medicine, Kanagawa
  4. Kyushu University Faculty of Medicine, Fukuoka


Although numerous clinical studies of peptide-based cancer vaccine were conducted in the past two decades, no sufficient outcome for drug approval was obtained at the present time.


To evaluate the safety and immune responses of a cancer vaccine consisting of 20 mixed peptides (KRM-20) in patients with castration-resistant prostate cancer (CRPC).


Patients received each of the randomly assigned three different doses of KRM-20 (6 mg/0.15 ml, 20 mg/0.5 ml or 60 mg/1.5 ml) once a week for 6 weeks. KRM-20 was applicable for patients with HLA-A2, A3, A11, A24, A26, A31, or A33 allele, covering the vast majority of population worldwide. Each group consisted of 5 patients. Peptide-specific cytotoxic T-lymphocyte (CTL) and immunoglobulin G (IgG) response, along with frequency of myeloid-derived suppressor cells (MDSC) and regulatory T cells were measured.


No serious adverse drug reactions were encountered. CTL response after 3rd vaccination was boosted for 3 of 59, 12 of 46, and 11 of 59 peptides tested in patients receiving 6, 20, and 60mg KRM-20, respectively. CTL response after 6th vaccination, however, largely decreased in patients receiving 60mg, in concomitant with strong boosting of IgG response. Frequency of regulatory T cells after 3rd or 6th vaccination was increased in 3 of 5 patients receiving 60mg or 6 mg KRM-20, respectively. Frequency of MDSC inversely correlated with CTL activity in patients receiving 20 mg KRM-20. Clinical responses determined by PSA levels were 2PR (from 20 mg group), 5SD, and 10 PD.


Twenty mg of KRM-20 could be recommended for a phase II study primarily because of lower levels of vaccine-induced suppression to CTL activity.