This study investigated the immunogenicity of Wilms tumor gene product 1 (WT1)–peptide vaccination in WT1-expressing acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) patients without curative treatment option. Vaccination consisted of granulocyte-macrophage colony-stimulating factor subcutaneously days 1 to 4, and WT1.126-134 peptide and 1 mg keyhole limpet hemocyanin on day 3. The initial 9 patients received 4 vaccinations biweekly, then monthly, and the subsequent 10 patients received continual biweekly vaccination. Seventeen AML patients and 2 refractory anemia with excess blasts patients received a median of 11 vaccinations. Treatment was well tolerated. Objective responses in AML patients were 10 stable diseases (SDs) including 4 SDs with more than 50% blast reduction and 2 with hematologic improvement. An additional 4 patients had clinical benefit after initial progression, including 1 complete remission and 3 SDs. WT1 mRNA levels decreased at least 3-fold from baseline in 35% of patients. In 8 of 18 patients, WT1-tetramer⁺ T cells increased in blood and in 8 of 17 patients in bone marrow, with a median frequency in bone marrow of 0.18% at baseline and 0.41% in week 18. This WT1 vaccination study provides immunologic, molecular, and preliminary evidence of potential clinical efficacy in AML patients, warranting further investigations.

Human malignant melanoma is highly resistant to chemotherapy and current immunotherapeutic approaches induce long term remission only in the minority of patients. The transforming growth factor-β (TGF-β) has attracted much attention as a therapeutic target because it plays an important and pleiotropic role in melanoma progression. TGF-β is a multifunctional cytokine involved in the regulation of many cellular processes including cell proliferation, differentiation and survival. Resistance to the growth inhibitory effects of TGF-β without alterations of TGF-β signaling molecules is characteristic of cutaneous melanoma. Melanoma produces increasing amounts of TGF-βwith disease progression, inhibiting immune responses and providing an optimal microenvironment for undisturbed tumor growth. In addition, TGF-β exerts its tumor promoting functions via direct effects on tumor cell motility and invasiveness and indirectly by modulating tumor stroma and extracellular matrix, supporting angiogenesis and inhibiting immune surveillance. TGF-β acts through multiple intracellular signaling pathways and the outcome of TGF-β signaling is context-dependent. Defining the impact of the different TGF-β signaling pathways on melanoma progression will help to identify suitable therapeutic targets. Here we review the current knowledge of TGF-β in melanoma and discuss recent therapeutic approaches targeting the TGF-β pathway.

The proteasome is responsible for selective degradation of proteins. It exists in mammalian cells under four main subtypes, which differ by the combination of their catalytic subunits: the standard proteasome (β1–β2–β5), the immunoproteasome (β1i–β2i–β5i) and the two intermediate proteasomes (β1–β2–β5i and β1i–β2–β5i). The efficiency of the four proteasome subtypes to degrade ubiquitinated or oxidized proteins remains unclear. Using cells expressing exclusively one proteasome subtype, we observed that ubiquitinated p21 and c-­myc were degraded at similar rates, indicating that the four 26S proteasomes degrade ubiquitinated proteins equally well. Under oxidative stress, we observed a partial dissociation of 26S into 20S proteasomes, which can degrade non-ubiquitinated oxidized proteins. Oxidized calmodulin and hemoglobin were best degraded in vitro by the three β5i-containing 20S proteasomes, while their native forms were not degraded. Circular dichroism analyses indicated that ubiquitin-independent recognition of oxidized proteins by 20S proteasomes was triggered by the disruption of their structure. Accordingly, β5i-containing 20S proteasomes degraded unoxidized naturally disordered protein tau, while 26S proteasomes did not. Our results suggest that the three β5i-containing 20S proteasomes, namely the immunoproteasome and the two intermediate proteasomes, might help cells to eliminate proteins containing disordered domains, including those induced by oxidative stress.

Purpose: The aim of this study was to determine in patients with high-risk primary uveal melanoma whether the detection of circulating tumor cells by quantitative reverse transcription-PCR (RT-PCR) is of prognostic relevance. Experimental Design: Blood samples from 110 patients with high-risk nonmetastatic uveal melanoma were collected on the occasion of primary treatment or follow-up visit. mRNA expression of tyrosinase and MelanA/MART1 were analyzed by real-time RT-PCR and compared with clinical data at presentation and follow-up by univariate and multivariate analyses. Results: The RT-PCR assay yielded a positive result in 11 of 110 patients, with five positive findings for tyrosinase and five for MelanA/MART1, and one sample positive for both markers. At a median follow-up of 22 months, 25% of patients had developed metastases and 15% had died. Univariate statistical analysis revealed RT-PCR and the largest tumor diameter as important prognostic factors for the development of metastases and for survival. In a Cox proportional hazard model, RT-PCR result and largest tumor diameter predicted metastases (hazard ratios 7.3 and 2.6, respectively), whereas PCR result, largest tumor diameter, and Karnofsky performance status were significant variables for disease-specific survival (hazard ratios 22.6, 4.7, and 6.0, respectively). Analysis of individual RT-PCR results revealed both tyrosinase and MelanA/MART1 transcripts as independent prognostic factors. Conclusion: The presence of tyrosinase or MelanA/MART1 transcripts is an independent prognostic factor in patients with high-risk primary uveal melanoma for subsequent development of metastases and for survival and can be used to select patients for adjuvant treatment studies.