Exposure to Melan-A/MART-126-35 tumor epitope specific CD8+T cells reveals immune escape by affecting the ubiquitin-proteasome system (UPS)

Efficient processing of target antigens by the ubiquitin-proteasome-system (UPS) is essential for treatment of cancers by T cell therapies. However, immune escape due to altered expression of IFN-γ-inducible components of the antigen presentation machinery and consequent inefficient processing of HLA- dependent tumor epitopes can be one important reason for failure of such therapies. Here, we show that short-term co-culture of Melan-A/MART-1 tumor antigen-expressing melanoma cells with Melan-A/MART-126-35-specific cytotoxic T lymphocytes (CTL) led to resistance against CTL-induced lysis because of impaired Melan-A/MART-126-35 epitope processing. Interestingly, deregulation of p97/VCP expression, which is an IFN-γ-independent component of the UPS and part of the ER-dependent protein degradation pathway (ERAD), was found to be essentially involved in the observed immune escape. In support, our data demonstrate that re-expression of p97/VCP in Melan-A/MART-126-35 CTL-resistant melanoma cells completely restored immune recognition by Melan-A/MART-126-35 CTL. In conclusion, our experiments show that impaired expression of IFN-γ-independent components of the UPS can exert rapid immune evasion of tumor cells and suggest that tumor antigens processed by distinct UPS degradation pathways should be simultaneously targeted in T cell therapies to restrict the likelihood of immune evasion due to impaired antigen processing

Assessment of prostate-specific antigen screening: an evidence-based report by the German Institute for Quality and Efficiency in Health Care

Context Prostate-specific antigen (PSA) testing increases prostate cancer diagnoses and reduces long-term disease-specific mortality, but also results in overdiagnoses and treatment-related harms. Objective To systematically assess the benefits and harms of population-based PSA screening and the potential net benefit to inform health policy decision-makers in Germany. Evidence Acquisition We performed a protocol-guided comprehensive literature search according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) statement. All steps were performed by one or two investigators; any discrepancies were resolved by consensus. To allow subgroup analyses for identifying the optimal screening parameters, the eight national trials conducted under the umbrella of the European Randomised study of Screening for Prostate Cancer (ERSPC) were included as individual trials. Evidence Synthesis We included a total 11 randomised controlled trials (RCTs) with a total of 416 000 study participants. For all-cause mortality, we found neither benefit nor harm. PSA screening was associated with a reduced risk of both prostate cancer mortality and the development of metastases. For the outcomes of health-related quality of life, adverse effects and the consequences of false-negative screening results there was no difference; however, this was due to the lack of eligible RCT data. Finally, PSA screening was associated with large numbers of overdiagnoses with adverse downstream consequences of unnecessary treatment (e.g. incontinence, erectile dysfunction) and large numbers of false-positive PSA tests leading to biopsies associated with a small but not negligible risk of complications. Limitations of this assessment include the clinical heterogeneity and methodological limitations of the underlying studies. Conclusions The benefits of PSA-based prostate cancer screening do not outweigh its harms. We failed to identify eligible screening studies of newer biomarkers, PSA derivatives or modern imaging modalities, which may alter the balance of benefit to harm. Patient Summary In the present study, we reviewed the evidence on the PSA blood test to screen men without symptoms for prostate cancer. We found that the small benefits experienced by some men do not outweigh the harms to many more men

Screening for sickle cell disease in newborns: a systematic review

Background!#!Sickle cell disease (SCD) is an inherited autosomal recessive disorder caused by the replacement of normal haemoglobin (HbA) by mutant Hb (sickle Hb, HbS). The sickle-shaped red blood cells lead to haemolysis and vaso-occlusion. Especially in the first years of life, patients with SCD are at high risk of life-threatening complications. SCD prevalence shows large regional variations; the disease predominantly occurs in sub-Saharan Africa. We aimed to systematically assess the evidence on the benefit of newborn screening for SCD followed by an earlier treatment start.!##!Methods!#!We systematically searched bibliographic databases (MEDLINE, EMBASE, Cochrane Databases, and the Health Technology Assessment Database), trial registries, and other sources to identify systematic reviews and randomised controlled trials (RCTs) or non-randomised trials on newborn screening for SCD. The last search was in 07/2020. Two reviewers independently reviewed abstracts and full-text articles and assessed the risk of bias of the studies included. Data were extracted by one person and checked by another. As meta-analyses were not possible, a qualitative summary of results was performed.!##!Results!#!We identified 1 eligible study with direct evidence: a Jamaican retrospective study evaluating newborn screening for SCD followed by preventive measures (prevention of infections and education of parents). The study included 500 patients with SCD (intervention group, 395; historical control group, 105). Although the results showed a high risk of bias, the difference between the intervention and the control group was very large: mortality in children decreased by a factor of about 10 in the first 5 years of life (0.02% in the intervention group vs. 0.19% in the control group, odds ratio 0.09; 95% confidence interval [0.04; 0.22], p < 0.001).!##!Conclusion!#!The results are based on a single retrospective study including historical controls. However, the decrease of mortality by a factor of 10 is unlikely to be explained by bias alone. Therefore, in terms of mortality, data from this single retrospective study included in our systematic review suggest a benefit of newborn screening for SCD (followed by preventive measures) versus no newborn screening for SCD (weak certainty of conclusions)

Evolution of melanoma cross-resistance to CD8+ T cells and MAPK inhibition in the course of BRAFi treatment

The profound but frequently transient clinical responses to BRAF(V600) inhibitor (BRAFi) treatment in melanoma emphasize the need for combinatorial therapies. Multiple clinical trials combining BRAFi and immunotherapy are under way to further enhance therapeutic responses. However, to which extent BRAF(V600) inhibition may affect melanoma immunogenicity over time remains largely unknown. To support the development of an optimal treatment protocol, we studied the impact of prolonged BRAFi exposure on the recognition of melanoma cells by T cells in different patient models. We demonstrate that autologous CD8(+) tumor-infiltrating lymphocytes (TILs) efficiently recognized short-term (3, 7days) BRAFi-treated melanoma cells but were less responsive towards long-term (14, 21days) exposed tumor cells. Those long-term BRAFi-treated melanoma cells showed a non-proliferative dedifferentiated phenotype and were less sensitive to four out of five CD8(+) T cell clones, present in the preexisting TIL repertoire, of which three recognized shared antigens (Tyrosinase, Melan-A and CSPG4) and one being neoantigen-specific. Only a second neoantigen was steadily recognized independent of treatment duration. Notably, in all cases the impaired T cell activation was due to a time-dependent downregulation of their respective target antigens. Moreover, combinatorial treatment of melanoma cells with BRAFi and an inhibitor of its downstream kinase MEK had similar effects on T cell recognition. In summary, MAP kinase inhibitors (MAPKi) strongly alter the tumor antigen expression profile over time, favoring evolution of melanoma variants cross-resistant to both T cells and MAPKi. Our data suggest that simultaneous treatment with MAPKi and immunotherapy could be most effective for tumor elimination

Preventing tumor escape by targeting a post-proteasomal trimming independent epitope

Adoptive T cell therapy (ATT) can achieve regression of large tumors in mice and humans; however, tumors frequently recur. High target peptide-major histocompatibility complex-I (pMHC) affinity and T cell receptor (TCR)-pMHC affinity are thought to be critical to preventing relapse. Here, we show that targeting two epitopes of the same antigen in the same cancer cells via monospecific T cells, which have similar pMHC and pMHC-TCR affinity, results in eradication of large, established tumors when targeting the apparently subdominant but not the dominant epitope. Only the escape but not the rejection epitope required postproteasomal trimming, which was regulated by IFN-γ, allowing IFN-γ–unresponsive cancer variants to evade. The data describe a novel immune escape mechanism and better define suitable target epitopes for ATT