Frameshift-derived neoantigens constitute immunotherapeutic targets for patients with microsatellite-instable haematological malignancies: frameshift peptides for treating MSI+ blood cancers

DNA damage response and neoantigens: A favorable target for triple-negative breast cancer immunotherapy and vaccine development

Triple-negative breast cancer (TNBC) poses a significant clinical challenge due to its aggressive nature and limited therapeutic options. The interplay between DNA damage response (DDR) mechanisms and the emergence of neoantigens represents a promising avenue for developing targeted immunotherapeutic strategies and vaccines for TNBC. The DDR is a complex network of cellular mechanisms designed to maintain genomic integrity. In TNBC, where genetic instability is a hallmark, dysregulation of DDR components plays a pivotal role in tumorigenesis and progression. This review explores the intricate relationship between DDR and neoantigens, shedding light on the potential vulnerabilities of TNBC cells. Neoantigens, arising from somatic mutations in cancer cells, represent unique antigens that can be recognized by the immune system. TNBC's propensity for genomic instability leads to an increased mutational burden, consequently yielding a rich repertoire of neoantigens. The convergence of DDR and neoantigens in TNBC offers a distinctive opportunity for immunotherapeutic targeting. Immunotherapy has revolutionized cancer treatment by harnessing the immune system to selectively target cancer cells. The unique immunogenicity conferred by DDR-related neoantigens in TNBC positions them as ideal targets for immunotherapeutic interventions. This review also explores various immunotherapeutic modalities, including immune checkpoint inhibitors (ICIs), adoptive cell therapies, and cancer vaccines, that leverage the DDR and neoantigen interplay to enhance anti-tumor immune responses. Moreover, the potential for developing vaccines targeting DDR-related neoantigens opens new frontiers in preventive and therapeutic strategies for TNBC. The rational design of vaccines tailored to the individual mutational landscape of TNBC holds promise for precision medicine approaches. In conclusion, the convergence of DDR and neoantigens in TNBC presents a compelling rationale for the development of innovative immunotherapies and vaccines. Understanding and targeting these interconnected processes may pave the way for personalized and effective interventions, offering new hope for patients grappling with the challenges posed by TNBCs.

Antigen presentation in cancer - mechanisms and clinical implications for immunotherapy

Over the past decade, the emergence of effective immunotherapies has revolutionized the clinical management of many types of cancers. However, long-term durable tumour control is only achieved in a fraction of patients who receive these therapies. Understanding the mechanisms underlying clinical response and resistance to treatment is therefore essential to expanding the level of clinical benefit obtained from immunotherapies. In this Review, we describe the molecular mechanisms of antigen processing and presentation in tumours and their clinical consequences. We examine how various aspects of the antigen-presentation machinery (APM) shape tumour immunity. In particular, we discuss genomic variants in HLA alleles and other APM components, highlighting their influence on the immunopeptidomes of both malignant cells and immune cells. Understanding the APM, how it is regulated and how it changes in tumour cells is crucial for determining which patients will respond to immunotherapy and why some patients develop resistance. We focus on recently discovered molecular and genomic alterations that drive the clinical outcomes of patients receiving immune-checkpoint inhibitors. An improved understanding of how these variables mediate tumour-immune interactions is expected to guide the more precise administration of immunotherapies and reveal potentially promising directions for the development of new immunotherapeutic approaches.

Outcome and Immune Correlates of a Phase II Trial of High-Dose Interleukin-2 and Stereotactic Ablative Radiotherapy for Metastatic Renal Cell Carcinoma

PURPOSE

This phase II clinical trial evaluated whether the addition of stereotactic ablative radiotherapy (SAbR), which may promote tumor antigen presentation, improves the overall response rate (ORR) to high-dose IL2 (HD IL2) in metastatic renal cell carcinoma (mRCC).

PATIENTS AND METHODS

Patients with pathologic evidence of clear cell renal cell carcinoma (RCC) and radiographic evidence of metastasis were enrolled in this single-arm trial and were treated with SAbR, followed by HD IL2. ORR was assessed based on nonirradiated metastases. Secondary endpoints included overall survival (OS), progression-free survival (PFS), toxicity, and treatment-related tumor-specific immune response. Correlative studies involved whole-exome and transcriptome sequencing, T-cell receptor sequencing, cytokine analysis, and mass cytometry on patient samples.

RESULTS

Thirty ethnically diverse mRCC patients were enrolled. A median of two metastases were treated with SAbR. Among 25 patients evaluable by RECIST v1.1, ORR was 16% with 8% complete responses. Median OS was 37 months. Treatment-related adverse events (AE) included 22 grade ≥3 events that were not dissimilar from HD IL2 alone. There were no grade 5 AEs. A correlation was observed between SAbR to lung metastases and improved PFS (P = 0.0165). Clinical benefit correlated with frameshift mutational load, mast cell tumor infiltration, decreased circulating tumor-associated T-cell clones, and T-cell clonal expansion. Higher regulatory/CD8+ T-cell ratios at baseline in the tumor and periphery correlated with no clinical benefit.

CONCLUSIONS

Adding SAbR did not improve the response rate to HD IL2 in patients with mRCC in this study. Tissue analyses suggest a possible correlation between frameshift mutation load as well as tumor immune infiltrates and clinical outcomes.

Lynch Syndrome and MSI-H Cancers: From Mechanisms to "Off-The-Shelf" Cancer Vaccines

Defective DNA mismatch repair (dMMR) is associated with many cancer types including colon, gastric, endometrial, ovarian, hepatobiliary tract, urinary tract, brain and skin cancers. Lynch syndrome - a hereditary cause of dMMR - confers increased lifetime risk of malignancy in different organs and tissues. These Lynch syndrome pathogenic alleles are widely present in humans at a 1:320 population frequency of a single allele and associated with an up to 80% risk of developing microsatellite unstable cancer (microsatellite instability - high, or MSI-H). Advanced MSI-H tumors can be effectively treated with checkpoint inhibitors (CPI), however, that has led to response rates of only 30-60% despite their high tumor mutational burden and favorable immune gene signatures in the tumor microenvironment (TME). We and others have characterized a subset of MSI-H associated highly recurrent frameshift mutations that yield shared immunogenic neoantigens. These frameshifts might serve as targets for off-the-shelf cancer vaccine designs. In this review we discuss the current state of research around MSI-H cancer vaccine development, its application to MSI-H and Lynch syndrome cancer patients and the utility of MSI-H as a biomarker for CPI therapy. We also summarize the tumor intrinsic mechanisms underlying the high occurrence rates of certain frameshifts in MSI-H. Finally, we provide an overview of pivotal clinical trials investigating MSI-H as a biomarker for CPI therapy and MSI-H vaccines. Overall, this review aims to inform the development of novel research paradigms and therapeutics.

Framing the potential of public frameshift peptides as immunotherapy targets in colon cancer

Approximately 15% of Colon Cancers are Microsatellite Instable (MSI). Frameshift Peptides (FPs) formed in MSI Colon Cancer are potential targets for immunotherapeutic strategies. Here we comprehensively characterize the mutational landscape of 71 MSI Colon Cancer patients from the cancer genome atlas (TCGA). We confirm that the mutations in MSI Colon Cancers are frequently frameshift deletions (23% in MSI; 1% in microsatellite stable), We find that these mutations cluster at specific locations in the genome which are mutated in up to 41% of the patients. We filter these for an adequate variant allele frequency, a sufficient mean mRNA level and the formation of a Super Neo Open Reading Frame (SNORF). Finally, we check the influence of Nonsense Mediated Decay (MMD) by comparing RNA and DNA sequencing results. Thereby we identify a set of 20 NMD-escaping Public FPs (PFPs) that cover over 90% of MSI Colon, 62.2% of MSI Endometrial and 58.8% of MSI Stomach cancer patients and 3 out of 4 Lynch patients in the TCGA-COAD. This underlines the potential for PFP directed immunotherapy, both in a therapeutic and a prophylactic setting in multiple types of MSI cancers.

Shared Immunogenic Poly-Epitope Frameshift Mutations in Microsatellite Unstable Tumors

Microsatellite instability-high (MSI-H) tumors are characterized by high tumor mutation burden and responsiveness to checkpoint blockade. We identified tumor-specific frameshifts encoding multiple epitopes that originated from indel mutations shared among patients with MSI-H endometrial, colorectal, and stomach cancers. Epitopes derived from these shared frameshifts have high population occurrence rates, wide presence in many tumor subclones, and are predicted to bind to the most frequent MHC alleles in MSI-H patient cohorts. Neoantigens arising from these mutations are distinctly unlike self and viral antigens, signifying novel groups of potentially highly immunogenic tumor antigens. We further confirmed the immunogenicity of frameshift peptides in T cell stimulation experiments using blood mononuclear cells isolated from both healthy donors and MSI-H cancer patients. Our study uncovers the widespread occurrence and strong immunogenicity of tumor-specific antigens derived from shared frameshift mutations in MSI-H cancer and Lynch syndrome patients, suitable for the design of common "off-the-shelf" cancer vaccines.

A Frameshift Peptide Neoantigen-Based Vaccine for Mismatch Repair-Deficient Cancers: A Phase I/IIa Clinical Trial

PURPOSE

DNA mismatch repair (MMR) deficiency is a hallmark of Lynch syndrome, the most common inherited cancer syndrome. MMR-deficient cancer cells accumulate numerous insertion/deletion mutations at microsatellites. Mutations of coding microsatellites (cMS) lead to the generation of immunogenic frameshift peptide (FSP) neoantigens. As the evolution of MMR-deficient cancers is triggered by mutations inactivating defined cMS-containing tumor suppressor genes, distinct FSP neoantigens are shared by most MMR-deficient cancers. To evaluate safety and immunogenicity of an FSP-based vaccine, we performed a clinical phase I/IIa trial (Micoryx).

PATIENTS AND METHODS

The trial comprised three cycles of four subcutaneous vaccinations (FSP neoantigens derived from mutant AIM2, HT001, TAF1B genes) mixed with Montanide ISA-51 VG over 6 months. Inclusion criteria were history of MMR-deficient colorectal cancer (UICC stage III or IV) and completion of chemotherapy. Phase I evaluated safety and toxicity as primary endpoint (six patients), phase IIa addressed cellular and humoral immune responses (16 patients).

RESULTS

Vaccine-induced humoral and cellular immune responses were observed in all patients vaccinated per protocol. Three patients developed grade 2 local injection site reactions. No vaccination-induced severe adverse events occurred. One heavily pretreated patient with bulky metastases showed stable disease and stable CEA levels over 7 months.

CONCLUSIONS

FSP neoantigen vaccination is systemically well tolerated and consistently induces humoral and cellular immune responses, thus representing a promising novel approach for treatment and even prevention of MMR-deficient cancer.

Correlations between microsatellite instability and the biological behaviour of tumours

Purpose

Microsatellites are widely distributed repetitive DNA motifs, accounting for approximately 3% of the genome. Due to mismatch repair system deficiency, insertion or deletion of repetitive units often occurs, leading to microsatellite instability. In this review, we aimed to explore the relationship between MSI and biological behaviour of colorectal carcinoma, gastric carcinoma, lymphoma/leukaemia and endometrial carcinoma, as well as the application of frameshift peptide vaccines in cancer therapy.

Methods

The relevant literature from PubMed and Baidu Xueshu were reviewed in this article. The ClinicalTrials.gov database was searched for clinical trials related to the specific topic.

Results

Microsatellite instability is divided into three subtypes: high-level, low-level microsatellite instability, and stable microsatellites. The majority of tumour patients with high-level microsatellite instability often show a better efficacy and prognosis than those with low-level microsatellite instability or stable microsatellites. In coding regions, especially for genes involved in tumourigenesis, microsatellite instability often results in inactivation of proteins and contributes to tumourigenesis. Moreover, the occurrence of microsatellite instability in coding regions can also cause the generation of frameshift peptides that are thought to be unknown and novel to the individual immune system. Thus, these frameshift peptides have the potential to be biomarkers to raise tumour-specific immune responses.

Conclusion

MSI has the potential to become a key predictor for evaluating the degree of malignancy, efficacy and prognosis of tumours. Clinically, MSI patterns will provide more valuable information for clinicians to create optimal individualized treatment strategies based on frameshift peptides vaccines.

An age-based, RNA expression paradigm for survival biomarker identification for pediatric neuroblastoma and acute lymphoblastic leukemia

Background

Pediatric cancer survival rates overall have been improving, but neuroblastoma (NBL) and acute lymphoblastic leukemia (ALL), two of the more prevalent pediatric cancers, remain particularly challenging. One issue not yet fully addressed is distinctions attributable to age of diagnosis.

Methods

In this report, we verified a survival difference based on diagnostic age for both pediatric NBL and pediatric ALL datasets, with younger patients surviving longer for both diseases. We identified several gene expression markers that correlated with age, along a continuum, and then used a series of age-independent survival metrics to filter these initial correlations.

Results

For pediatric NBL, we identified 2 genes that are expressed at a higher level in lower surviving patients with an older diagnostic age; and 4 genes that are expressed at a higher level in longer surviving patients with a younger diagnostic age. For pediatric ALL, we identified 3 genes expressed at a higher level in lower surviving patients with an older diagnostic age; and 17 genes expressed at a higher level in longer surviving patients with a younger diagnostic age.

Conclusions

This process implicated pan-chromosome effects for chromosomes 11 and 17 in NBL; and for the X chromosome in ALL.

Electronic supplementary material

The online version of this article (10.1186/s12935-019-0790-5) contains supplementary material, which is available to authorized users.

MMP7 sensitivity of mutant ECM proteins: An indicator of melanoma survival rates and T-cell infiltration

OBJECTIVE

To assess the potential impact of mutant ECM amino acids (AA) on melanoma-related matrix metalloproteinase-7 (MMP7) activity.

DESIGN AND METHODS

We applied a novel scripted algorithm, based on the MEROPS database, to reveal mutant-dependent sensitivity changes across the cancer genome atlas, melanoma dataset.

RESULTS

This approach revealed a strong bias in favor of mutant AA dependent protease sensitivity increases. Thus, melanoma specimens with relatively few mutations had only MMP7 mutant sensitive, ECM peptides. As mutations increased, melanoma specimens included mutant AA representing mostly increased sensitivity and a small but increasing number of mutant AA representing decreased MMP7 sensitivity. There was no detection of melanoma specimens with only decreases in MMP7 sensitivity. Furthermore, melanoma specimens with exclusively increased sensitivity and thereby only a few overall mutations represented reduced T-cell infiltrates and worse outcomes.

CONCLUSIONS

Overall, the results indicated that changes in MMP7 sensitivity, attributable to mutant AA, have the potential of identifying patients with distinct survival outcomes as well as patients with cancer specimen immune activity.

PD-L1 expression and presence of TILs in small intestinal neuroendocrine tumours

BACKGROUND

The extent of resistance to immune surveillance in patients with well-differentiated (Wd) (grade 1/2) small-intestinal neuroendocrine tumours (Si-NETs) is unknown.

METHODS

Patients diagnosed with Wd Si-NETs (excluding appendix, which are considered to have a different biology to other midgut NETs) were eligible. Tumoural programmed death (PD)-ligand(L) 1 (PD-L1)/PD-L2/PD-1 and tumour infiltrating lymphocytes (TILs) [presence and phenotype] were analysed in archival tissue by immunohistochemistry (IHC); reverse transcription quantitative polymerase chain reaction (RT-qPCR) was used for confirmation of IHC results.

RESULTS

Of 109 patients screened, 62 were eligible: 54.8% were male; median age was 63.7 years (95%-CI 59.7-67.2); disease stage II: 4.8%, III: 40.3% and IV: 54.8%; 41.9% were functional. Analysed samples (67.1% from primary tumours, 32.9% from metastases) were of grade 1 (67.1%) or 2 (32.86%) with a median Ki-67 of 2%. From the total of 62 eligible patients, 70 and 63 samples were suitable for IHC and RT-qPCR analysis, respectively. PD-L1 expression within tumour cells and TILs were identified in 12.8% and 24.3% of samples respectively; 30% of samples showed PD-L1 expression within tumour cells and/or TILs. PD-1 was present in TILs in 22.8% of samples. Majority of samples showed significant presence of CD4+ (focal 42.86%; moderate 2.86%) and CD8+ (focal 92.86%; moderate 4.29%) TILs. IHC findings were confirmed with RT-qPCR; which showed higher expression levels of PD-L1 (p-value 0.007) and PD-1 (p-value 0.001) in samples positive for IHC compared to negative-IHC.

CONCLUSIONS

Thirty-percent of patients express PD-L1 within tumour cells and/or TILs. Identification of presence of TILs was also significant and warrant the investigation of immunotherapy in this setting.

Exploiting non-canonical translation to identify new targets for T cell-based cancer immunotherapy

Cryptic MHC I-associated peptides (MAPs) are produced via two mechanisms: translation of protein-coding genes in non-canonical reading frames and translation of allegedly non-coding sequences. In general, cryptic MAPs are coded by relatively short open reading frames whose translation can be regulated at the level of initiation, elongation or termination. In contrast to conventional MAPs, the processing of cryptic MAPs is frequently proteasome independent. The existence of cryptic MAPs derived from allegedly non-coding regions enlarges the scope of CD8 T cell immunosurveillance from a mere ~2% to as much as ~75% of the human genome. Considering that 99% of cancer-specific mutations are located in those allegedly non-coding regions, cryptic MAPs could furthermore represent a particularly rich source of tumor-specific antigens. However, extensive proteogenomic analyses will be required to determine the breath as well as the temporal and spatial plasticity of the cryptic MAP repertoire in normal and neoplastic cells.

The mutational profile and infiltration pattern of murine MLH1-/- tumors: concurrences, disparities and cell line establishment for functional analysis

Mice lines homozygous negative for one of the four DNA mismatch repair (MMR) genes (MLH1, MSH2, PMS2, MSH6) were generated as models for MMR deficient (MMR-D) diseases. Clinically, hereditary forms of MMR-D include Lynch syndrome (characterized by a germline MMR gene defect) and constitutional MMR-D, the biallelic form. MMR-D knockout mice may be representative for both diseases. Here, we aimed at characterizing the MLH1^-/- model focusing on tumor-immune microenvironment and identification of coding microsatellite mutations in lymphomas and gastrointestinal tumors (GIT).

All tumors showed microsatellite instability (MSI) in non-coding mononucleotide markers. Mutational profiling of 26 coding loci in MSI⁺ GIT and lymphomas revealed instability in half of the microsatellites, two of them (Rfc3 and Rasal2) shared between both entities. MLH1^-/- tumors of both entities displayed a similar phenotype (high CD71, FasL, PD-L1 and CTLA-4 expression). Additional immunofluorescence verified the tumors’ natural immunosuppressive character (marked CD11b/CD200R infiltration). Vice versa, CD3⁺ T cells as well as immune checkpoints molecules were detectable, indicative for an active immune microenvironment. For functional analysis, a permanent cell line from an MLH1^-/- GIT was established. The newly developed MLH1^-/- A7450 cells exhibit stable in vitro growth, strong invasive potential and heterogeneous drug response. Moreover, four additional MSI target genes (Nktr1, C8a, Taf1b, and Lig4) not recognized in the primary were identified in this cell line.

Summing up, molecular and immunological mechanisms of MLH1^-/- driven carcinogenesis correlate well with clinical features of MMR-D. MLH1^-/- knockout mice combine characteristics of Lynch syndrome and constitutional MMR-D, making them suitable models for preclinical research aiming at MMR-D related diseases.

Cellular vaccination of MLH1-/- mice - an immunotherapeutic proof of concept study

Mismatch-repair deficiency (MMR-D) is closely linked to hypermutation and accordingly, high immunogenicity. MMR-D-related tumors thus constitute ideal vaccination targets for both therapeutic and prophylactic approaches. Herein, the prophylactic and therapeutic impact of a cellular vaccine on tumor growth and tumor-immune microenvironment was studied in a murine MLH1^-/- knockout mouse model. Prophylactic application of the lysate (+/- CpG ODN 1826) delayed tumor development, accompanied by increased levels of circulating T cell numbers. Therapeutic application of the vaccine prolonged overall survival (median time: 11.5 (lysate) and 12 weeks (lysate + CpG ODN) vs. 3 weeks (control group), respectively) along with reduced tumor burden, as confirmed by PET/CT imaging and immune stimulation (increased CD3⁺CD8⁺ T - and NK cell numbers, reduced levels of TIM-3⁺ cells in both treatment groups). Coding microsatellite analysis of MMR-D-related target genes revealed increased mutational load upon vaccination (total mutation frequency within 28 genes: 28.6% vaccine groups vs. 14.9% control group, respectively). Reactive immune cells recognized autologous tumor cells, but also NK cells target YAC-1 in IFNγ ELISpot and, even more importantly, in functional kill assays. Assessment of tumor microenvironment revealed infiltration of CD8⁺ T-cells and granulocytes, but also upregulation of immune checkpoint molecules (LAG-3, PD-L1). The present study is the first reporting in vivo results on a therapeutic cellular MMR-D vaccine. Vaccination-induced prolonged survival was achieved in a clinically-relevant mouse model for MMR-D-related diseases by long-term impairment of tumor growth and this could be attributed to re-activated immune responses.

Lung tumor exome files with T-cell receptor recombinations: a mouse model of T-cell infiltrates reflecting mutation burdens

Tumor exomes and RNASeq data were originally intended for obtaining tumor mutations and gene expression profiles, respectively. However, recent work has determined that tumor exome and RNAseq read files contain reads representing T-cell and B-cell receptor (TcR and BcR) recombinations, presumably due to infiltrating lymphocytes. Furthermore, the recovery of immune receptor recombination reads has demonstrated correlations with specific, previously appreciated aspects of tumor immunology. To further understand the usefulness of recovering TcR and BcR recombinations from tumor exome files, we developed a scripted algorithm for recovery of reads representing these recombinations from a previously described mouse model of lung tumorigenesis. Results indicated that exomes representing lung adenomas reveal significantly more TcR recombinations than do exomes from lung adenocarcinomas; and that exome files representing high mutation adenomas, arising from chemical mutagens, have more TcR recombinations than do exome files from low mutation adenomas arising from an activating Kras mutation. The latter results were also consistent with a similar analysis performed on human lung adenocarcinoma exomes. The mouse and human results for obtaining TcR recombination reads from tumor specimen exomes are consistent with human tumor biology results indicating that adenomas and high mutation cancers are sites of high immune activity. The results indicate hitherto unappreciated opportunities for the use of tumor specimen exome files, particularly from experimental animal models, to study the connection between the adenoma stage of tumorigenesis, or high cancer mutation rates, and high level lymphocyte infiltrates.

Inactivation of DNA repair triggers neoantigen generation and impairs tumour growth

Molecular alterations in genes involved in DNA mismatch repair (MMR) promote cancer initiation and foster tumour progression. Cancers deficient in MMR frequently show favourable prognosis and indolent progression. The functional basis of the clinical outcome of patients with tumours that are deficient in MMR is not clear. Here we genetically inactivate MutL homologue 1 (MLH1) in colorectal, breast and pancreatic mouse cancer cells. The growth of MMR-deficient cells was comparable to their proficient counterparts in vitro and on transplantation in immunocompromised mice. By contrast, MMR-deficient cancer cells grew poorly when transplanted in syngeneic mice. The inactivation of MMR increased the mutational burden and led to dynamic mutational profiles, which resulted in the persistent renewal of neoantigens in vitro and in vivo, whereas MMR-proficient cells exhibited stable mutational load and neoantigen profiles over time. Immune surveillance improved when cancer cells, in which MLH1 had been inactivated, accumulated neoantigens for several generations. When restricted to a clonal population, the dynamic generation of neoantigens driven by MMR further increased immune surveillance. Inactivation of MMR, driven by acquired resistance to the clinical agent temozolomide, increased mutational load, promoted continuous renewal of neoantigens in human colorectal cancers and triggered immune surveillance in mouse models. These results suggest that targeting DNA repair processes can increase the burden of neoantigens in tumour cells; this has the potential to be exploited in therapeutic approaches.

Genomic Profiling of Biliary Tract Cancers and Implications for Clinical Practice

OPINION STATEMENT

Biliary tract cancers are relatively uncommon, have an aggressive disease course and a dismal clinical outcome. Until recently, there have been very few clinical advances in the management of these patients and gemcitabine-based chemotherapy has been the only widely accepted systemic therapy. The advent of next generation sequencing technologies can potentially change the treatment paradigm of this disease. Targeted therapy directed against actionable mutations and identification of molecular subsets with distinct prognostic significance is now feasible in clinical practice. Mutation profiling has highlighted the genomic differences between the intra, extrahepatic cholangiocarcinoma, and gallbladder cancer. The mutational spectrum of intrahepatic cholangiocarcinoma differs according to geographic location and ethnicity. There is a higher incidence of chromatin modulating gene mutations in Western patients as compared with Asian patients with liver fluke-associated cholangiocarcinoma. KRAS and p53 mutations are associated with an aggressive disease prognosis while FGFR mutations may signify a relatively indolent disease course of intrahepatic cholangiocarcinoma. FGFR and IDH mutations have promising agents in clinical trials at this time. An estimated 15 % of gallbladder cancers have Her2/neu amplification and can be targeted by trastuzumab. On the other hand, an estimated 10-15 % of cholangiocarcinomas have DNA repair mutations and may be candidates for immune therapies with checkpoint inhibitors. The promise of targeted therapies for biliary tract cancers can be fulfilled with well-designed, prospective, and multi-center clinical trials.

Microsatellite Instability and Promoter Hypermethylation of DNA repair genes in Hematologic Malignancies: a forthcoming direction toward diagnostics

OBJECTIVE

The objective of our review is to highlight the significance of microsatellite hypervariation in diagnostics of hematologic malignancies.

METHODS

For the past few decades, extensive experiments in cancer research have explored all the possible pathways and a number of deleterious mutations that either make the tumor suppressor genes (TSGs) dysfunctional or cause the proto-oncogenes to behave abnormally by changing the cellular phenotype hence rendering disease. To prevent the deleterious effects of mutations and to protect the genomic integrity, our system possesses multiple repair mechanisms. DNA Mismatch Repair (MMR) and Direct Reversal of Damage (DRD) are two repair mechanisms which help in removal of faulty base pairs and alkyl adduct formation respectively to avoid long term effects of toxicity, tumorigenesis and mutagenesis. There are nine major MMR genes - MutS homolog (MSH2, MSH3, MSH4, MSH5, MSH6), MutL homolog (MLH1, MLH3), human post-meiotic segregation genes (PMS1, PMS2), and three major damage reversal genes - O⁶-methylguanine-DNA-methyltransferase (MGMT), ABH2 and DEPC1.

RESULTS

Any malfunction in DNA repair machinery can cause microsatellite instability (MSI), a form of genomic abnormality with hyper mutable repeats that is directly associated with cancer. Microsatellites are short, repetitive sequences, non-randomly distributed and localized in 3'-UTR (Untranslated Region), introns, coding regions and promoters. Besides MSI, evidence on promoter hypermethylation of selected repair genes also points toward a prominent reason for cancer initiation and progression.

CONCLUSION

The presence of specific microsatellite marker hyper-mutability and consistent promoter hypermethylation in leukemia or lymphoma can be considered as a part of routine diagnostic test in clinical laboratories.

T cell receptor gene recombinations in human tumor specimen exome files: detection of T cell receptor-β VDJ recombinations associates with a favorable oncologic outcome for bladder cancer

Understanding tumor-resident T cells is important for cancer prognosis and treatment options. Conventional, solid tumor specimen exome files can be searched directly for recombined T cell receptor (TcR)-α segments; RNASeq files can include TcR-β VDJ recombinations. To learn whether there are medically relevant uses of exome-based detection of TcR V(D)J recombinations in the tumor microenvironment, we searched cancer genome atlas and Moffitt Cancer Center, tumor specimen exome files for TcR-β, TcR-γ, and TcR-δ recombinations, for bladder and stomach cancer. We found that bladder cancer exomes with productive TcR-β recombinations had a significant association with No Subsequent Tumors and a positive response to drug treatments, with p < 0.004, p < 0.05, and p < 0.004, depending on the sample sets examined. We also discovered the opportunity to detect productive TcR-γ and TcR-δ recombinations in the tumor microenvironment, via the tumor specimen exome files.

Identification of immunoglobulin V(D)J recombinations in solid tumor specimen exome files: Evidence for high level B-cell infiltrates in breast cancer

It has recently become apparent that it is possible to characterize productively recombined, T-cell receptor (TcR) gene segments in tumor exome files, which presumably include representations of the DNA of other cells in the microenvironment. Similar characterizations have been done for TcR recombinations in tumor specimen RNASeq files. While exome files have been used to characterize immunoglobulin gene segment recombinations for tumors closely related to B-cells, immunoglobulin recombinations have yet to be characterized for putative microenvironment cells for solid tumors. Here we report a novel scripted algorithm that detects productive and unproductive immunoglobulin recombinations in both B-cell related tumor exome files and in solid tumor exome files, with the most important result being the relatively high level B-cell infiltrate in breast cancer. This analysis has the potential of streamlining and dramatically augmenting the knowledge base regarding B-cell infiltrates into solid tumors; and leading to antibody reagents directed against tumor antigens and tissue resident, infectious pathogens.

The Immune Biology of Microsatellite-Unstable Cancer

Deficient DNA mismatch repair (MMR) boosts the accumulation of frameshift mutations in genes encompassing coding microsatellites (cMS). This results in the translation of proteins with mutation-induced frameshift peptides (neoantigens) rendering microsatellite-unstable (MSI) cancers highly immunogenic. MSI cancers express a defined set of neoantigens resulting from functionally relevant driver mutations, which are shared by most MSI cancers. Patients with MSI cancers and healthy individuals affected by Lynch syndrome, an inherited predisposition for MSI cancers, develop specific immune responses against these neoantigens. In this review, we summarize our current understanding of the immune biology of MSI cancers and outline new concepts and research directions to develop not only therapeutic treatments, but also preventive vaccines based on the MSI cancer genome landscapes.

Reactivity against microsatellite instability-induced frameshift mutations in patients with inflammatory bowel disease

AIM

To analyze the cellular immune response towards microsatellite-instability (MSI)-induced frameshift-peptides (FSPs) in patients suffering from inflammatory bowel disease (IBD) with and without thiopurine-based immunosuppressive treatment.

METHODS

Frequencies of peripheral blood T cell responses of IBD patients (n = 75) against FSPs derived from 14 microsatellite-containing candidate genes were quantified by interferon-γ enzyme-linked immunospot. T cells derived from 20 healthy individuals served as controls.

RESULTS

Significant T cell reactivities against MSI-induced FSPs were observed in 59 of 75 IBD patients (78.7%). This was significantly more as we could observe in 20 healthy controls (P = 0.001). Overall, the reactivity was significantly influenced by thiopurine treatment (P = 0.032) and duration of disease (P = 0.002) but not by duration or cumulative amount of thiopurine therapy (P = 0.476). Unexpected, 15 of 24 (62.5%) IBD patients without prior thiopurine treatment also showed increased FSP-specific immune responses (P = 0.001).

CONCLUSION

These findings propose FSPs as potential novel class of inflammation-associated antigens and this in turn may have implications for screening, diagnosis as well as clinical management of patients suffering from IBD and other inflammatory conditions.

Surgery in the era of the 'omics revolution

BACKGROUND

Surgery is entering a new phase with the revolution in genomic technology. Cheap, mass access to next-generation sequencing is now allowing the analysis of entire human genomes at the DNA and RNA level. These data sets are being used increasingly to identify the molecular differences that underlie common surgical diseases, and enable them to be stratified for patient benefit.

METHODS

This article reviews the recent developments in the molecular biology of colorectal, oesophagogastric and breast cancer.

RESULTS

The review specifically covers developments in genetic predisposition, next-generation sequencing studies, biomarkers for stratification, prognosis and treatment, and other 'omics technologies such as metabolomics and proteomics.

CONCLUSION

There are unique opportunities over the next decade to change the management of surgical disease radically, using these technologies. The directions that this may take are highlighted, including future advances such as the 100,000 Genomes Project.

A personalized view on cancer immunotherapy

Recent progress in cancer immunotherapy has resulted in complete responses in patients refractory to current standard cancer therapies. However, due to tumor heterogeneity and inter-individual variations in anti-tumor immunity, only subsets of patients experience clinical benefit. This review highlights the implementation of a personalized approach to enhance treatment efficacy and reduce side effects, including the identification of tumor-specific antigens for cancer vaccination and adoptive T cell therapies. Furthermore, together with the current advances and promising clinical outcomes of combination cancer (immuno-)therapies, the screening for predictive biomarkers in a patient-specific manner is emphasized.

Microsatellite instability in hematological malignancies: Hypermutation vs. immune control-who is challenging who?

The genome of colorectal carcinomas displaying pronounced microsatellite instability codes for an extraordinarily high number of mutated proteins that elicit tumor-specific cellular immune responses. We have recently demonstrated that leukemic cells are also vulnerable to T cells specific for tumor-associated antigens produced in the context of microsatellite instability. This finding extends our understanding of secondary and therapy-related leukemogenesis, linking it to the mutual interaction between immune control and escape.