Early phase II study of mixed 19-peptide vaccine monotherapy for refractory triple-negative breast cancer.

We undertook an early phase II study of mixed 19-peptide cancer vaccine monotherapy for 14 advanced metastatic triple-negative breast cancer (mTNBC) patients refractory to systemic chemotherapy to develop a new type of cancer vaccine. The treatment protocol consisted of a weekly vaccination for 6 weeks, and there were no severe adverse events related to the vaccination throughout the trial. Increase of peptide-specific IgG against the vaccinated human leukocyte antigen-matched peptides, but not against the nonmatched peptides, was positively correlated with overall survival (OS) (P < .01). The median OS was 11.5 or 24.4 months in all 14 patients or the 10 patients who completed the vaccination. The patients with lower C-reactive protein levels or 3 or fewer systemic chemotherapies were favorable candidates for this treatment. Advancement of this therapy to the next stage of study could be warranted based on the safety and immune boosting determined herein (clinical trial registration number: UMIN000014616).

Predictive factors of the tumor immunological microenvironment for long-term follow-up in early stage breast cancer.

The aim of this research was to investigate the correlation of immunologic factors in the tumor environment of breast cancer, using immunohistological staining to evaluate the expression of programmed death 1/programmed death ligand 1 (PD-1/PD-L1), phosphatase and tensin homolog (PTEN), tumor infiltrating lymphocytes (TILs), and macrophages, and to analyze the association between the immunologic factors and clinical outcome for patients with early stage breast cancer (EBC). A total of 97 EBC patients who underwent standard surgery were investigated. Expression of PD-1/PD-L1 and PTEN and the density of CD3+ TILs, CD8+ TILs, and CD163+ macrophages were evaluated by immunohistochemical analysis. The association between the immunologic factors and clinical outcome was statistically analyzed. The density of CD3+ TILs, CD8+ TILs, and CD163+ macrophages and non-expression of PTEN was significantly higher in cases of triple negative breast cancer. CD8+ TIL density and CD8+ /PD-L1+ expression were predictive factors for disease-free survival and overall survival (OS). Human epidermal growth factor 2 (HER2)-positive patients with PTEN expression and luminal/HER2-negative patients without PD-L1 expression had significantly longer OS compared to patients without PTEN expression (P = 0.049) and with PD-L1 expression (P = 0.036), respectively. Furthermore, patients with PD-L1+ /CD8+ expression had worse median progression-free survival (P = 0.022) and median OS (P = 0.037) compared with patients without PD-L1+ /CD8+ expression. The CD3+ TILs, CD8+ TILs, and CD163+ macrophages were shown to infiltrate the tumor area of EBC. In particular, triple negative breast cancer had a higher rate of TIL infiltration within the tumor environment. Expression of PTEN and lack of PD-L1 expression were associated with favorable survival in HER2-positive and luminal/HER2-negative EBC patients, respectively. The PD-L1 expression combined with CD8+ density was significantly associated with an aggressive clinical outcome.

[Development of Peptide Vaccines for Triple-Negative Breast Cancer Treatment].

Our previous phase II clinical trial showed that therapeutically selected personalized peptide vaccines(PPVs)were effective at boosting anticancer immunity; the immune response after PPV was associated with a clinical outcome as a prognostic factor for metastatic breast cancer(mBC). We conducted an early phase II study to evaluate the safety and efficacy of a new regimen using multiple peptide vaccines(KRM-19)for patients with metastatictriple -negative breast cancer. KRM-19 consisted of 19 mixed peptides chosen from the previously reported 31 PPVs according to their anti-tumor immunologiceffec ts and safety profiles for patients with mBC. All patients had histologically confirmed measurable ER-PgR-HER2- mBC and their human leukocyte antigen(HLA) / -A molecules were A2, A3, A11, A24, A26, A31, or A33. KRM-19(19mg/mL)was administrated subcutaneously every week for a total of 6 doses. Concurrent conventional chemo- and/or endocrine therapy were not permitted during treatment. This was an open-label, early phase II study. The primary endpoint was safety and anti-tumor immunologic effect, while the secondary endpoints were clinical responses and progression-free survival(PFS). The estimated enrollment was 10-15 and 8 patients were enrolled(Clinical trial registry number: UMIN000014616). Measurement of peptide-specific cytotoxic T lymphocyte and IgG responses were conducted before and after vaccination. The correlation between PFS and the increased IgG response and/or CTL levels were investigated.

[Pretreatment and Posttreatment Evaluations of Circulating Tumor Cells（CTC）in Patients with Metastatic Breast Cancer].

Recently, circulating tumor cells (CTCs) of cancer patients have been analyzed as a biomarker of disease progression and as a new prognostic tool.We conducted a pilot study to determine whether CTCs present before and after chemotherapy or peptide vaccination predicted outcome in patients with metastatic breast cancer (MBC). CTCs were isolated from the peripheral blood of MBC patients and evaluated using the CellSearch®System (Janssen Diagnostics). The expression of the HLA classⅠ molecule in the CTCs was analyzed simultaneously by using a flow cytometric system. A CTC-positive test result was defined as five or more CTCs/7.5 mL blood. Nine patients (median [range] age, 64.2 years [44-80 years]) were included. Four (57.1%) of 7 MBC patients with Luminal A subtype tested positive for CTC.Of 6 MBC patients, 5 (83.3%) had a decreased mean number of CTCs, from 35.8/7.5 to 0.4/7.5 mL, after 3 courses of systemic chemotherapy. Furthermore, CTC-HLA class Ⅰexpression level was decreased in 2 (66.7%) of 3 patients after cytotoxic chemotherapy but increased in 4 (80.0%) of 5 patients after 6 vaccinations with tumor-specific peptide vaccines. The number of CTCs and CTC-HLA class Ⅰ expression level in the patients with MBC changed after the treatment with systemic chemotherapy or peptide-vaccine therapy.