Chiara Martinoli

Cancer immunotherapy based on killing of Salmonella-infected tumor cells

A major obstacle for the development of effective immunotherapy is the ability of tumors to escape the immune system. The possibility to kill tumor cells because they are recognized as infected rather than as malignant could help overcome immune escape mechanisms. Here we report a conceptually new approach of cancer immunotherapy based on in vivo infection of tumors and killing of infected tumor cells. Attenuated but still invasive, Salmonella typhimurium can be successfully exploited to invade melanoma cells that can present antigenic determinants of bacterial origin and become targets for anti-Salmonella-specific T cells. However, to fully appreciate the anticancer therapeutic properties of S. typhimurium, tumor-bearing mice need to be vaccinated against S. typhimurium before intratumoral Salmonella injection. Tumor infection when coupled to anti-Salmonella vaccination leads to 50% to 100% tumor-free mice with a better outcome on larger tumors. Invasive Salmonella also exert an indirect toxic effect on tumor cells through the recruitment of inflammatory cells and the cross-presentation of tumor antigens, which allow induction of tumor-specific immune response. This is effective in retarding the growth of untreated established distant tumors and in protecting the mice from subsequent tumor challenges.

Baseline neutrophil-to-lymphocyte ratio is associated with outcome of ipilimumab-treated metastatic melanoma patients

Background:Ipilimumab improves the survival of metastatic melanoma patients. Despite documented, durable objective responses, a significant number of patients fails to benefit from treatment. The aim of this study was to identify an upfront marker for treatment benefit.Methods:A total of 187 metastatic melanoma patients treated in three Italian Institutions with 3 mg kg−1 ipilimumab, and 27 patients treated with 10 mg kg−1 ipilimumab, were evaluated. Neutrophil-to-lymphocyte ratio (NLR) was calculated from pre-therapy full blood counts. Progression-free survival (PFS) and overall survival (OS) were assessed using the Kaplan–Meier method, and multivariate Cox models were applied, adjusting for confounders and other prognostic factors.Results:In the training cohort of 69 patients treated at European Institute of Oncology, pre-therapy NLR was identified as the strongest and independent marker for treatment benefit in multivariate analyses. Patients with baseline NLR<5 had a significantly improved PFS (HR=0.38; 95% CI: 0.22–0.66; P=0.0006) and OS (HR=0.24; 95% CI: 0.13–0.46; P<0.0001) compared with those with a NLR⩾5. Associations of low NLR with improved survival were confirmed in three validation cohorts of patients.Conclusion:Our findings show that baseline NLR is strongly and independently associated with outcome of patients treated with ipilimumab, and may serve to identify patients most likely to benefit from this therapy.

Baseline neutrophils and derived neutrophil-to-lymphocyte ratio: prognostic relevance in metastatic melanoma patients receiving ipilimumab

BACKGROUND Clinical responses to ipilimumab are variable in terms of onset, magnitude and duration. Upfront identification of patients who are more likely or unlikely to benefit from treatment is a major need. PATIENTS AND METHODS Prospectively collected data from 720 advanced melanoma patients treated with ipilimumab 3 mg/kg within the Italian expanded access program were analyzed. The derived neutrophil-to-lymphocyte ratio (dNLR) was calculated from baseline peripheral blood cell counts, and receiver operating characteristic curve was used to evaluate the best cutoff for this marker. Patients were stratified according to dichotomized baseline absolute neutrophil counts (ANC), dNLR and their combination. The prognostic values of ANC and dNLR for survival were assessed using multivariate Cox proportional hazard models. A subgroup analysis including LDH in the models was also carried out. RESULTS The median follow-up was 16.5 months. The optimal cutoff for dNLR was 3. Baseline ANC and dNLR were significantly associated with the outcome of ipilimumab-treated melanoma patients, in terms of disease progression and death (P < 0.0001 for all). Furthermore, for each elevated variable, prognosis worsened. Patients with both ANC ≥ 7500 and dNLR ≥ 3 had a significantly and independently increased risk of death [hazard ratio(HR) = 5.76; 95% confidence interval (CI) 4.29-7.75] and of progression (HR = 4.10; 95% CI 3.08-5.46) compared with patients with both lower ANC and dNLR. Patients with one of the two factors elevated displayed an intermediate risk of progression and death. The 1- and 2-year survival rates were 2% and 0%, respectively, for patients with ANC ≥ 7500 and dNLR ≥ 3, and 43% and 24%, respectively, for patients with both lower ANC and dNLR. CONCLUSIONS Although these findings need to be confirmed and validated, we suggest that a neutrophil-based index may help risk-group stratification and assist disease-management strategies. Furthermore, the potential predictive value of this index for response to ipilimumab should be investigated in randomized clinical trials.

Bacterial Sensor Triggering Receptor Expressed on Myeloid Cells-2 Regulates the Mucosal Inflammatory Response

BACKGROUND AND AIMS Triggering receptor expressed on myeloid cells (TREM)-2 is a surface receptor detected on macrophages, dendritic cells, and microglia that binds repeated anionic motifs on yeast and Gram-positive and Gram-negative bacteria. Little is known about TREM-2 expression and function in the intestine or its role in inflammatory bowel disease (IBD). We investigated the expression of TREM-2 in the intestinal lamina propria and its role in the development of colonic inflammation. METHODS We measured levels of TREM-2 in lamina propria mononuclear cells from surgical specimens collected from patients with IBD or cancer (controls). We analyzed the development of colitis in TREM-2 knockout and wild-type mice. Colon samples were isolated from mice and analyzed for cytokine expression, phagocytosis of bacteria, proliferation in colonic crypts, lamina propria mononuclear cell function, and T-cell activation by ovalbumin. RESULTS TREM-2 was virtually absent from colon samples of control patients, but levels were significantly higher in within the inflamed mucosa of patients with IBD; it was mainly expressed by CD11c(+) cells. Levels of TREM-2 increased as acute or chronic colitis was induced in mice. TREM-2 knockout mice developed less severe colitis than wild-type mice; the knockout mice lost less body weight, had a lower disease activity index, and had smaller mucosal lesions in endoscopic analysis. Colon dendritic cells from TREM-2 knockout mice produced lower levels of inflammatory cytokines and had reduced levels of bacterial killing and T-cell activation than cells from wild-type mice. CONCLUSIONS TREM-2 contributes to mucosal inflammation during development of colitis in mice. Levels of TREM-2 are increased within the inflamed mucosa of patients with IBD, indicating its potential as a therapeutic target.

Personalised medicine: Development and external validation of a prognostic model for metastatic melanoma patients treated with ipilimumab

PURPOSE The purpose of this study was to set up a prognostic model for the identification of survival predictors specific for melanoma patients treated with ipilimumab. EXPERIMENTAL DESIGN The following prospectively collected data were utilised: patient and primary tumour characteristics, relapse-free-interval, site and number of metastases, previous therapies and level of serum biomarkers (lactic dehydrogenase (LDH), C-reactive protein, β2-microglobulin, vascular endothelial growth factor (VEGF), IL2, IL6, S-100, alkaline phosphatase (ALP), transaminases, leucocyte count, lymphocytes subpopulations). A multivariate prognostic model was developed using the Cox regression model fitted to the data of 113 consecutive metastatic patients treated with ipilimumab (3 mg/kg, q3w) at Veneto Institute of Oncology (IOV). External validation was obtained using the data of 69 and 34 patients treated at European Oncology Institute (IEO) and University of Torino (UT), respectively. RESULTS Median survival was 8.3, 4.9 and 7.1 months from first ipilimumab administration at IOV, IEO and UT, respectively. Both higher baseline levels of LDH (Hazard Ratio [HR] v=1.36, 95% Confidence Interval [CI] 1.16-1.58, P<.001) and neutrophils (HR=1.76, 95% CI 1.41-2.10, P<.001) were associated with worse prognosis. Model performance was satisfactory both upon internal validation (Dxy=0.42) and external validation (Dxy=0.40). Serum LDH and neutrophil count discriminated patients who lived more (low neutrophils and low LDH) or less (high LDH or neutrophils) than 24 months. CONCLUSION Serum LDH and neutrophil count were significant independent prognostic factors. This externally validated prognostic nomogram, could help clinicians to identify the patients who would benefit most from ipilimumab and consequently to improve resource allocation. These easily available biomarkers deserve further validation.

Selective Infection of Antigen-Specific B Lymphocytes by Salmonella Mediates Bacterial Survival and Systemic Spreading of Infection

Background The bacterial pathogen Salmonella causes worldwide disease. A major route of intestinal entry involves M cells, providing access to B cell-rich Peyer’s Patches. Primary human B cells phagocytose Salmonella typhimurium upon recognition by the specific surface Ig receptor (BCR). As it is unclear how Salmonella disseminates systemically, we studied whether Salmonella can use B cells as a transport device for spreading. Methodology/Principal Findings Human primary B cells or Ramos cell line were incubated with GFP-expressing Salmonella. Intracellular survival and escape was studied in vitro by live cell imaging, flow cytometry and flow imaging. HEL-specific B cells were transferred into C57BL/6 mice and HEL-expressing Salmonella spreading in vivo was analyzed investigating mesenteric lymph nodes, spleen and blood. After phagocytosis by B cells, Salmonella survives intracellularly in a non-replicative state which is actively maintained by the B cell. Salmonella is later excreted followed by reproductive infection of other cell types. Salmonella-specific B cells thus act both as a survival niche and a reservoir for reinfection. Adoptive transfer of antigen-specific B cells before oral infection of mice showed that these B cells mediate in vivo systemic spreading of Salmonella to spleen and blood. Conclusions/Significance This is a first example of a pathogenic bacterium that abuses the antigen-specific cells of the adaptive immune system for systemic spreading for dissemination of infection.

Heat-shock proteins-based immunotherapy for advanced melanoma in the era of target therapies and immunomodulating agents.

Introduction: Heat-shock proteins (HSPs) are highly conserved, stress-induced proteins that function as chaperones, stabilizing proteins and delivering peptides. Tumor-derived HSP peptide complexes (HSPPCs) induced immunity against several malignancies in preclinical models, exhibiting activity across tumor types. Areas covered: HSPPC-based vaccination showed clinical activity in subsets of patients with different malignancies (e.g., gastric, colorectal, pancreatic, ovarian cancer, and glioblastoma). In Phase III clinical trials for advanced melanoma and renal cell carcinoma patients, HSPPC-based vaccine demonstrated an excellent safety profile, thus emerging as a flexible tumor- and patient-specific therapeutic approach. Expert opinion: Melanoma, renal clear cell carcinoma, and glioblastoma are among suitable targets for HSP-based treatment as demonstrated by immune responses and clinical activity observed in subsets of patients, mainly those with early stage of disease and limited tumor burden. In order to further improve clinical activity, combinations of HSPPC-based vaccines with mutation-driven therapies, antiangiogenic agents, or immunomodulating monoclonal antibodies should be tested in controlled clinical trials.

Sunny Holidays before and after Melanoma Diagnosis Are Respectively Associated with Lower Breslow Thickness and Lower Relapse Rates in Italy

Background Previous studies have reported an association between sun exposure and improved cutaneous melanoma (CM) survival. We analysed the association of UV exposure with prognostic factors and outcome in a large melanoma cohort. Methods A questionnaire was given to 289 (42%) CM patients at diagnosis (Group 1) and to 402 CM patients (58%) during follow-up (Group 2). Analyses were carried out to investigate the associations between sun exposure and melanoma prognostic factors and survival. Results Holidays in the sun two years before CM diagnosis were significantly associated with lower Breslow thickness (p=0.003), after multiple adjustment. Number of weeks of sunny holidays was also significantly and inversely associated with thickness in a dose-dependent manner (p=0.007). However when stratifying by gender this association was found only among women (p=0.0004) the risk of CM recurrence in both sexes was significantly lower in patients (n=271) who had holidays in the sun after diagnosis, after multiple adjustment including education: HR=0.30 (95%CI:0.10-0.87; p=0.03) conclusions: Holidays in the sun were associated with thinner melanomas in women and reduced rates of relapse in both sexes. However, these results do not prove a direct causal effect of sun exposure on survival since other confounding factors, such as vitamin D serum levels and socio-economic status, may play a role. Other factors in sun seeking individuals may also possibly affect these results.

Prognostic significance of hematological profiles in melanoma patients

Cancer‐related inflammation may play an important role in disease progression and patient outcome, and could be easily monitored through indirect parameters routinely evaluated at diagnosis. Here, we investigated if peripheral blood cells and the ratios of neutrophils to lymphocytes (NLR) and of lymphocytes to monocytes (LMR) as surrogate markers of cancer related inflammation are associated with disease progression and survival of melanoma patients at any stage of the disease. Records of 1,182 melanoma patients included in an Institutional tumor registry in the period 2000–2010, were reviewed. Among them, 584 patients with a cutaneous or unknown primary melanoma and available pre‐operative blood tests were analyzed. Survival was estimated with the Kaplan–Meier method, and analyzed using Log‐rank test, Cox regression and multivariate Cox proportional hazard models. We found that patients presenting with distant metastases had higher leukocytes, neutrophils and monocytes, and lower lymphocytes compared to Stage I–III patients. Furthermore, at a single‐patient level, hematological profiles changed on disease progression from regional to distant metastatic, with significantly increased circulating leukocytes, neutrophils and monocytes, and decreased lymphocytes. Peripheral blood cell counts were not associated with survival of patients with a localized or regionally metastasized melanoma. Instead, in Stage IV patients, leukocytes (p = 0.001), neutrophils (p = 0.0002), monocytes (p = 0.002), NLR (p < 0.0001) and LMR (p = 0.005) were all significantly associated with survival, independently of other known prognostic factors. These results suggest that cellular components of peripheral blood do count for survival of patients with advanced melanoma.

Newly identified tumor antigens as promising cancer vaccine targets for malignant melanoma treatment.

Immunogenicity of tumour cells, immunomodulation and direct targeting of signalling pathways are promising avenues and matter of dated and innovative research in melanoma. Unfortunately, tumour cells are considered to be antigenic, but not immunogenic, either due to presentation of weakly recognized antigens or to the inability of the immune system to recognize them. However, spontaneous complete remission can be rarely observed in patients affected by melanoma, which are mainly attributed to the immune response against the tumour. Also, an elevated frequency of spontaneous humoral immune responses against tumour antigens was occasionally found in patients. These data confirm the existence of an interaction of the immune system with the tumour which can be used as a promising pathway for intervention and incorporates all portions of the immune system. The cancer immunotherapy approach is based on artificial activation of the immune system against the tumour and groups several types of treatments including immunization/vaccination but also modulation of immunity by cytokines or antibodies. Immunization approaches could either be based on undefined tumour antigens (e.g. whole tumour cells, tumour cell lysates, or tumour-antigen enriched fractions) or aimed at eliciting T-cell responses against specific tumour antigens. Novel and contemporary antigen-targeted therapy strategies, mainly directed to Cancer Testis and Heat Shock Proteins, leading to a possible active immunization against melanoma through T-cell specific activation, are discussed in this review.