Lack of Elevation of Serum S100B in Patients with Metastatic Melanoma as a Predictor of Outcome After Induction with an Autologous Vaccine of Proliferating Tumor Cells and Dendritic Cells

The calcium-binding protein S100B reduces IL6 production in malignant melanoma via inhibition of RSK cellular signaling

S100B is frequently elevated in malignant melanoma. A regulatory mechanism was uncovered here in which elevated S100B lowers mRNA and secreted protein levels of interleukin-6 (IL6) and inhibits an autocrine loop whereby IL6 activates STAT3 signaling. Our results showed that S100B affects IL6 expression transcriptionally. S100B was shown to form a calcium-dependent protein complex with the p90 ribosomal S6 kinase (RSK), which in turn sequesters RSK into the cytoplasm. Consistently, S100B inhibition was found to restore phosphorylation of a nuclear located RSK substrate, CREB, which is a potent transcription factor for IL6 expression. Thus, elevated S100B reduces IL6-STAT3 signaling via RSK signaling pathway in malignant melanoma. Indeed, the elevated S100B levels in malignant melanoma cell lines correspond to low levels of IL6 and p-STAT3.

Programmed death-1 receptor (PD-1) and PD-ligand-1 (PD-L1) expression in non-small cell lung cancer and the immune-suppressive effect of anaerobic glycolysis

The microenvironment of a tumor may regulate the anti-tumor immune response. Intratumoral acidosis and hypoxia may suppress lymphocyte proliferation and migration, and this may have important implications in modern immunotherapy. The expression of PD-L1 by cancer cells and of PD-1 by tumor infiltrating lymphocytes (TILs) was assessed in tissue specimens from 98 operable NSCLC patients. Their prognostic role and their association with makers of glycolysis and anaerobic metabolism were assessed. Strong cytoplasmic/membrane PD-L1 expression was noted in 45/98 cases. Intense presence of TILs was noted in 42/98 cases (high TIL-score), and intense presence of PD-1 expressing TILs (high PIL-score) in 17/98 cases. PD-L1 expression was directly correlated with high PIL-score (p = 0.005). A significant inverse relationship was found between lactate dehydrogenase LDH5 expression and PIL-score (p = 0.008). Similarly, low PIL-score was significantly linked with high-hexokinase HXKII and monocarboxylate transporter MCT2 expression (p < 0.04). Cases with both intense TIL-score and PIL-score had significantly better survival (p < 0.05). For patients with high TIL-score or high PIL-score, PD-L1 overexpression defined significantly poorer survival (p = 0.01 and p = 0.03, respectively). In multivariate analysis, stage (p = 0.002, HR 3.33, 95%CI 1.4-4.5) and TIL-score (p = 0.02, HR 2.12, 95%CI 1.1-4.0) were independent predictive variables of death events. Given the low specificity of PD-L1 as a biomarker for anti-PD-1/PD-L1 immunotherapy, a combined assessment of TIL, PD-L1, PD-1, and LDH5 provides a tool for an immunological/metabolic classification of NSCLC tumors, with a different prognosis and different expected response to anti-PD-1/PD-L1 immunotherapy, which should be considered in relevant clinical trials.

Small Molecule Inhibitors of Ca(2+)-S100B Reveal Two Protein Conformations

The drug pentamidine inhibits calcium-dependent complex formation with p53 ((Ca)S100B·p53) in malignant melanoma (MM) and restores p53 tumor suppressor activity in vivo. However, off-target effects associated with this drug were problematic in MM patients. Structure-activity relationship (SAR) studies were therefore completed here with 23 pentamidine analogues, and X-ray structures of (Ca)S100B·inhibitor complexes revealed that the C-terminus of S100B adopts two different conformations, with location of Phe87 and Phe88 being the distinguishing feature and termed the "FF-gate". For symmetric pentamidine analogues ((Ca)S100B·5a, (Ca)S100B·6b) a channel between sites 1 and 2 on S100B was occluded by residue Phe88, but for an asymmetric pentamidine analogue ((Ca)S100B·17), this same channel was open. The (Ca)S100B·17 structure illustrates, for the first time, a pentamidine analog capable of binding the "open" form of the "FF-gate" and provides a means to block all three "hot spots" on (Ca)S100B, which will impact next generation (Ca)S100B·p53 inhibitor design.

Covalent small molecule inhibitors of Ca(2+)-bound S100B

Elevated levels of the tumor marker S100B are observed in malignant melanoma, and this EF-hand-containing protein was shown to directly bind wild-type (wt) p53 in a Ca(2+)-dependent manner, dissociate the p53 tetramer, and inhibit its tumor suppression functions. Likewise, inhibiting S100B with small interfering RNA (siRNA(S100B)) is sufficient to restore wild-type p53 levels and its downstream gene products and induce the arrest of cell growth and UV-dependent apoptosis in malignant melanoma. Therefore, it is a goal to develop S100B inhibitors (SBiXs) that inhibit the S100B-p53 complex and restore active p53 in this deadly cancer. Using a structure-activity relationship by nuclear magnetic resonance approach (SAR by NMR), three persistent binding pockets are found on S100B, termed sites 1-3. While inhibitors that simultaneously bind sites 2 and 3 are in place, no molecules that simultaneously bind all three persistent sites are available. For this purpose, Cys84 was used in this study as a potential means to bridge sites 1 and 2 because it is located in a small crevice between these two deeper pockets on the protein. Using a fluorescence polarization competition assay, several Cys84-modified S100B complexes were identified and examined further. For five such SBiX-S100B complexes, crystallographic structures confirmed their covalent binding to Cys84 near site 2 and thus present straightforward chemical biology strategies for bridging sites 1 and 3. Importantly, one such compound, SC1982, showed an S100B-dependent death response in assays with WM115 malignant melanoma cells, so it will be particularly useful for the design of SBiX molecules with improved affinity and specificity.

Immunity to melanin and to tyrosinase in melanoma patients, and in people with vitiligo

Background

The aim of this study was to determine the presence and the intensity of humoral immunity to melanoma-associated antigens: tyrosinase and melanin, in patients with melanoma, in persons with vitiligo and in control healthy people.

Methods

The study involved 63 patients with melanoma and 19 persons with vitiligo. Control group consisted up to 41 healthy volunteers. Mushroom tyrosinase and synthetic melanin were used as the antigens.

Results

ELISA test showed significantly (p < 0.0000004 and p < 0.04) lower levels of IgM anti-tyrosinase autoantibodies, in melanoma and vitiligo patients respectively, compared to controls.

Although there was no significant difference between the levels of IgA anti-melanin autoantibodies in melanoma or vitiligo patients in comparison with controls, the enhanced concentrations of anti-melanin IgA autoantibodies were preferentially found in melanoma patients with metastatic disease. Significantly high percentage in the Fc alphaRI (CD89) positive cells was determined in melanoma patients (p < 0.002 and p < 0.008) in comparison to that found in healthy people or in patients with vitiligo, in the already mentioned order, pointing that IgA dependent cellular cytotoxicity is not important for the immune action against melanoma, even more that it is included in some immune suppression.

Levels of IgG autoantibodies to mentioned antigens in melanoma patients although low were not significantly lower from controls. These findings analyzed together with the statistically significant low percentage of FcgammaRIII, (CD16) positive immunocompetent cells (p < 0.0007 and p < 0.003), which was found in patients with melanoma compared with healthy or vitiligo people respectively, and statistically significant low percentage of (CD16 + CD56+) natural killer (NK) cells (p < 0.005) found in melanoma patients in comparison to healthy controls pointed to the low probability for anti-melanoma IgG mediated, antibody mediated cellular cytotoxicity, (ADCC) and NK cytotoxicity. Moreover the ratio of the percentages of granulocytes and percentage of lymphocytes was statistically higher in patients with melanoma in relation to healthy people as well as to people with vitiligo (p < 0.0007 and p < 0.05 respectively).

Conclusion

Autoantibodies to tyrosinase and to melanin which are found even in healthy people, point that consummation of edible mushrooms that carry the antigen tyrosinase and melanin, could influence the humoral anti-melanoma immune response.

Levels of different immunoglobulin classes of anti-melanin and anti-tyrosinase antibodies varied depending on the presence and the stage of studied diseases. Besides, the statistically enhanced ratio of the percentages of granulocytes and percentage of lymphocytes, together with statistically decreased percentage of NK cells is found in analyzed melanoma patients.

Features associated with survival in metastatic melanoma patients treated with patient-specific dendritic cell vaccines

Previously, a 54% 5-year survival was reported for metastatic melanoma patients treated with patient-specific vaccines consisting of autologous dendritic cells loaded with antigens from autologous proliferating tumor cells. This study attempted to determine which clinical and laboratory factors best explained long-term survival in this group of patients. Univariate analyses were used to identify factors associated with continuous survival after initiating vaccine therapy. Multivariate logistic regression was used to identify independent factors to classify survival at 3.5 years. Survivors were followed a minimum of 3.7 years (median: 5.7). Univariate analyses identified eight features associated with improved survival: Eastern Cooperative Oncology Group (ECOG) performance status (PS) of 0, no measurable disease at study entry, receiving 8 vaccinations, age <50 years, normal baseline lactate dehydrogenase, no history of visceral metastases, anergy to standard skin tests, and failure of interferon-gamma (IFN-γ) to induce apoptosis in autologous tumor cells. After examining 54 variables for which complete information was available over all patients, the best multivariate regression for survival at 3.5 years utilized six features: prior radiation therapy, younger age, male gender, ECOG PS 0, higher numbers of cells administered during the first 3 injections, and lower numbers of viable cells administered during the first 3 injections. This model correctly classified survival for 28 of 32 patients (87%) and death for 20 of 22 (91%). When features with incomplete information were included in the analysis, addition of IFN-γ-induced apoptosis (n=49) improved predictive accuracy to 27 of 29 (93%) for survival and 19 of 20 (95%) for death. Dependencies between variables were common, but these multivariate linear models yielded high classification accuracy for survival at 3.5 years and identified two features of the vaccine itself as being of independent significance.

Establishment of stable cell lines for personalized melanoma cell vaccine

Personalized vaccine, recognized after the failure of allogenic melanoma whole cell and lysate vaccine phase III trials, involves culturing cells from a patient's own tumor within a short duration and with less passages but with optimized expression of tumor-associated antigens (TAAs). Its feasibility is established by comparing pure cell lines generated from fresh and cryopreserved tissues (n=164) of patients with lymph node (LN) and distant metastases. Stable cell lines (from 67% of specimens) are subcultured after cryopreserving them. Pure cell lines established after eliminating fibroblasts (from 96% of the cell lines) include those from LN (69%), soft tissues including cutaneous (60%), liver (64%), lung (75%), bone (80%), brain (75%), and other sites (73%). Within 3.5 months, stable cell lines (> or =50 million cells) are established from initiating the cell culture. For LN metastases, the duration differs significantly (P2<0.05) between fresh (1.4-3.4 months) and cryopreserved (2.4-4.7 months) tissues. The expression of TAAs varies as follows: Tyrosinase (81%) >Melan-A (80%) >HMB45/gp-100 (75%) >Mel-5/TRP-1 (65%) >MAGE-1 (47%) > S-100 (28%). The number of TAAs per cell line differs between early (<7) and late (>7) passages. Among late passage cell lines, lesser percentage of cell lines express three to six antigens pointing out that early passage (<7) cell lines may be needed for antigen-targeted immunotherapy. This study provides a protocol for establishing cell lines within 2-5 months for personalized vaccine therapy for nodal and organ metastatic melanoma patients.