Integration of Cell-Free DNA End Motifs and Fragment Lengths Can Identify Active Genes in Liquid Biopsies.

Multiple studies have shown that cell-free DNA (cfDNA) from cancer patients differ in both fragment length and fragment end motif (FEM) from healthy individuals, yet there is a lack of understanding of how the two factors combined are associated with cancer and gene transcription. In this study, we conducted cfDNA fragmentomics evaluations using plasma from lung cancer patients (n = 12) and healthy individuals (n = 7). A personal gene expression profile was established from plasma using H3K36me3 cell-free chromatin immunoprecipitation sequencing (cfChIP-seq). The genes with the highest expression displayed an enrichment of short cfDNA fragments (median = 19.99%, IQR: 16.94-27.13%, p < 0.0001) compared to the genes with low expression. Furthermore, distinct GC-rich FEMs were enriched after cfChIP. Combining the frequency of short cfDNA fragments with the presence of distinct FEMs resulted in an even further enrichment of the most expressed genes (median = 37.85%, IQR: 30.10-39.49%, p < 0.0001). An in vitro size selection of <150 bp cfDNA could isolate cfDNA representing active genes and the size-selection enrichment correlated with the cfChIP-seq enrichment (Spearman r range: 0.499-0.882, p < 0.0001). This study expands the knowledge regarding cfDNA fragmentomics and sheds new light on how gene activity is associated with both cfDNA fragment lengths and distinct FEMs.

DNAfusion: an R/Bioconductor package for increased sensitivity of detecting gene fusions in liquid biopsies.

BACKGROUND: EML4-ALK gene fusions are oncogenic drivers in non-small cell lung cancer (NSCLC), and liquid biopsies containing EML4-ALK fragments can be used to study tumor dynamics using next-generation sequencing (NGS). However, the sensitivity of EML4-ALK detection varies between pipelines and analysis tools. RESULTS: We developed an R/Bioconductor package, DNAfusion, which can be applied to BAM files generated by commercially available NGS pipelines, such as AVENIO. Forty-eight blood samples from a training cohort consisting of 41 stage IV EML4-ALK-positive NSCLC patients and seven healthy controls were used to develop DNAfusion. DNAfusion detected EML4-ALK in significantly more samples (sensitivity = 61.0%) compared to AVENIO (sensitivity = 36.6%). The newly identified EML4-ALK-positive patients were verified using droplet digital PCR. DNAfusion was subsequently validated in a blinded validation cohort comprising 24 EML4-ALK-positive and 24 EML4-ALK-negative stage IV NSCLC patients. DNAfusion detected significantly more EML4-ALK individuals in the validation cohort (sensitivity = 62.5%) compared to AVENIO (sensitivity = 29.2%). DNAfusion demonstrated a specificity of 100% in both the training and validation cohorts. CONCLUSION: Here we present DNAfusion, which increases the sensitivity of EML4-ALK detection in liquid biopsies and can be implemented downstream of commercially available NGS pipelines. The simplistic method of operating the R package makes it easy to implement in the clinical setting, enabling wider expansion of NGS-based diagnostics.

Cell-Free DNA and Clinical Characteristics in Patients with Small Intestinal or Pancreatic Neuroendocrine Tumors.

INTRODUCTION: Neuroendocrine tumors (NETs) are rare and characterized by a heterogeneous clinical course and an unmet need for better prognostic markers. Plasma cell-free DNA (cfDNA) has prognostic value in other malignancies but is not previously investigated in NETs. We studied cfDNA levels in patients with mainly low-grade small intestinal NET -(siNET) or pancreatic NET (pNET) and evaluated the prognostic potential of cfDNA. MATERIALS AND METHODS: We included 70 NET patients, siNET (n = 50) and pNET (n = 20). Plasma cfDNA levels were determined by droplet digital PCR for the beta-2-microglobulin gene every 6 months during a period of 3 years, including in a subgroup of 19 patients during peptide receptor radionuclide therapy (PRRT) therapy. RESULTS: cfDNA levels were higher in both siNET and pNET compared to a previously established healthy cohort (p < 0.0001). -cfDNA levels did not predict overall survival (crude hazard ratio [HR] 0.95 [0.57-1.58], p = 0.837, adjusted for smoking status HR 0.77 [0.51-1.17], p = 0.22). The impact of cfDNA level on progression-free survival showed different trends in siNET and pNET. There was no effect of PRRT treatment on cfDNA levels and no difference in cfDNA levels between patients with and without progressive disease after PRRT (ANOVA p = 0.66). cfDNA levels were significantly higher in never-smokers and previous smokers than in current smokers (p = 0.029). DISCUSSION/CONCLUSION: cfDNA levels are higher in NET patients than in healthy controls; however, there was no association with prognosis, and cfDNA levels were unaffected by PRRT. Our observations suggest that cfDNA levels are not associated with the disease course in low-grade NET in contrast to other malignancies.

Combining tissue and circulating tumor DNA increases the detection rate of a CTNNB1 mutation in hepatocellular carcinoma.

BACKGROUND AND AIMS: Studies suggest that mutations in the CTNNB1 gene are predictive of response to immunotherapy, an emerging therapy for advanced hepatocellular carcinoma (HCC). Analysis of circulating tumor DNA (ctDNA) offers the possibility of serial non-invasive mutational profiling of tumors. Combining tumor tissue and ctDNA analysis may increase the detection rate of mutations. This study aimed to evaluate the frequency of the CTNNB1 p.T41A mutation in ctDNA and tumor samples from HCC patients and to evaluate the concordance rates between plasma and tissue. We further evaluated changes in ctDNA after various HCC treatment modalities and the impact of the CTNNB1 p.T41A mutation on the clinical course of HCC. METHODS: We used droplet digital PCR to analyze plasma from 95 patients and the corresponding tumor samples from 37 patients during 3 years follow up. RESULTS: In tumor tissue samples, the mutation rate was 8.1% (3/37). In ctDNA from HCC patients, the CTNNB1 mutation rate was 9.5% (9/95) in the pre-treatment samples. Adding results from plasma analysis to the subgroup of patients with available tissue samples, the mutation detection rate increased to 13.5% (5/37). There was no difference in overall survival according to CTNNB1 mutational status. Serial testing of ctDNA suggested a possible clonal evolution of HCC or arising multicentric tumors with separate genetic profiles in individual patients. CONCLUSION: Combining analysis of ctDNA and tumor tissue increased the detection rate of CTNNB1 mutation in HCC patients. A liquid biopsy approach may be useful in a tailored therapy of HCC.

Total cell-free DNA, carcinoembryonic antigen, and C-reactive protein for assessment of prognosis in patients with metastatic colorectal cancer.

In late-stage metastatic colorectal cancer, difficult treatment decisions should incorporate a thorough evaluation of the patient's general condition and subject for shared decision making. Assessment of the individual patients' prognosis is valuable in this setting. The aim was to analyze the prognostic value of plasma levels of total cell-free DNA, carcinoembryonic antigen and C-reactive protein in 97 heavily pretreated patients with metastatic colorectal cancer. Patients received irinotecan, cetuximab, and everolimus in a phase-2 clinical trial ( clinicaltrials.gov NCT01387880). Plasma samples were used for DNA purification and quantification of total cell-free DNA by droplet digital polymerase chain reaction. Serum carcinoembryonic antigen and C-reactive protein were analyzed by routine methods. Clinical endpoints were overall survival and progression-free survival. A total of 82 patients had blood samples available for quantification of total cell-free DNA. Patients with pre-treatment cell-free DNA levels higher than the median total cell-free DNA (9800 alleles per milliliter plasma) had a significantly shorter overall survival of 4.3 months (95% confidence interval: 3.6-5.8) compared to patients with cell-free DNA levels below the median with an overall survival of 11.3 months (95% confidence interval: 8.0-14.8, p < 0.0001). When using the upper normal limit from a previously analyzed normal control group, the median overall survival was 11.3 (95% confidence interval: 7.3-14.8) and 4.3 (95% confidence interval: 3.7-6.1) months, respectively (p < 0.0001). Serum carcinoembryonic antigen and C-reactive protein had similar prognostic value with short overall survival and progression-free survival in patients with elevated levels compared to those within normal range. A high-risk profile of elevated cell-free DNA, carcinoembryonic antigen, and C-reactive protein was described, but in combined Cox regression multivariate analysis, only total cell-free DNA preserved a strong prognostic value. In conclusion, total cell-free DNA in plasma, carcinoembryonic antigen, and C-reactive protein could all contribute to assessment of patients' prognosis and potentially aid in clinical decision making in patients with metastatic colorectal cancer.

The T790M resistance mutation in EGFR is only found in cfDNA from erlotinib-treated NSCLC patients that harbored an activating EGFR mutation before treatment.

BACKGROUND: Lung cancer patients with an activating mutation in the EGFR (epidermal growth factor receptor) can develop resistance to erlotinib treatment, which is often mediated by the T790M resistance mutation in EGFR. The difficulties in obtaining biopsies at progression make it challenging to investigate the appearance of the T790M mutation at progression in large patient cohorts. We have used cell free DNA (cfDNA) from patients treated with erlotinib to investigate if the development of a T790M mutation coincides with the presence of an activating EGFR mutation in the pre-treatment blood sample. METHODS: A cohort of 227 NSCLC (non-small cell lung cancer) adenocarcinoma patients was treated with erlotinib irrespective of EGFR-mutational status. Blood samples were drawn immediately before erlotinib treatment was initiated and again at progression. The cobas® EGFR Mutation Test v2 designed for cfDNA was used to identify 42 EGFR mutations. RESULTS: Of the 227 NSCLC patients, blood samples were available from 144 patients both before erlotinib treatment and at progression (within 1 month before or after clinical progression). One hundred and twenty-eight of the 144 were wild-type EGFR before treatment, and we demonstrate that the T790M mutation was not present at progression in any of these. In contrast, in the 16 patients with an activating EGFR mutation in the pre-treatment blood sample six patients (38%) were identified with a T790M mutation in the progression blood sample. CONCLUSION: The T790M resistance mutation is only found in the cfDNA of erlotinib-treated NSCLC patients if they have an activating EGFR mutation before treatment.

Correlation between circulating mutant DNA and metabolic tumour burden in advanced non-small cell lung cancer patients.

BACKGROUND: Mutated circulating cell-free DNA (cfDNA) has been suggested as a surrogate marker of tumour burden and aggressiveness of disease. We examined the association between the level of plasma mutant cfDNA and metabolic tumour burden (MTB) measured by 18F-fluoro-D-glucose positron emission tomography/computed tomography (18F-FDG PET/CT). Furthermore, the presence of mutant cfDNA was correlated with patient survival. METHODS: Forty-six advanced non-small cell lung cancer (NSCLC) patients were included. At the time of inclusion, blood sampling and a PET/CT scan were performed. cfDNA was isolated and next-generation sequencing (NGS) was performed (Ion AmpliSeq Colon and Lung Cancer panel v2). MTB was defined by a volumetric PET parameter. RESULTS: NGS succeeded in 41 patients. Mutations were detected in the blood of 24 patients. A significant correlation between the allele frequency of the most frequent mutation and MTB was found (P=0.001). Patients with detectable mutated cfDNA had a significantly shorter median overall survival compared with patients without (3.7 versus 10.6 months, P=0.019). This impact on survival was independent of the MTB. CONCLUSIONS: Level of mutated cfDNA tends to correlate with MTB in advanced-stage NSCLC patients. Patients with detectable mutant DNA in plasma had an inferior survival, indicating that this could be an important predictor of survival.

Cell-free DNA levels and correlation to stage and outcome following treatment of locally advanced rectal cancer.

Accurate staging of rectal cancer remains essential for optimal patient selection for combined modality treatment, including radiotherapy, chemotherapy and surgery. We aimed at examining the correlation of cell free DNA with the pathologic stage and subsequent risk of recurrence for patients with locally advanced rectal cancer undergoing preoperative chemoradiation. We examined 75 patients with locally advanced rectal cancer receiving preoperative chemoradiation. Blood samples for translational use were drawn prior to rectal surgery. The level of cell free DNA was quantified by digital droplet PCR and expressed as copy number of beta 2 microglobulin. We found a median level of cell free DNA in the AJCC stages I-III of 3100, 8300, and 10,700 copies/mL respectively. For patients with 12 sampled lymph nodes or above, the median level of cell free DNA were 2400 copies/mL and 4400 copies/mL (p = 0.04) for node negative and node positive disease respectively. The median follow-up was 39 months and 11 recurrences were detected (15%). The median level for patients with recurrent disease was 13,000 copies/mL compared to 5200 copies/mL for non-recurrent patients (p = 0.08). We have demonstrated a correlation between the level of total cell free DNA and the pathologic stage and nodal involvement. Furthermore, we have found a trend towards a correlation with the risk of recurrence following resection of localized rectal cancer.

Regulatory dissection of the CBX5 and hnRNPA1 bi-directional promoter in human breast cancer cells reveals novel transcript variants differentially associated with HP1α down-regulation in metastatic cells.

BACKGROUND: The three members of the human heterochromatin protein 1 (HP1) family of proteins, HP1α, HP1ß, and HPγ, are involved in chromatin packing and epigenetic gene regulation. HP1α is encoded from the CBX5 gene and is a suppressor of metastasis. CBX5 is down-regulated at the transcriptional and protein level in metastatic compared to non-metastatic breast cancer. CBX5 shares a bi-directional promoter structure with the hnRNPA1 gene. But whereas CBX5 expression is down-regulated in metastatic cells, hnRNAP1 expression is constant. Here, we address the regulation of CBX5 in human breast cancer. METHODS: Transient transfection and transposon mediated integration of dual-reporter mini-genes containing the bi-directional hnRNPA1 and CBX5 promoter was performed to investigate transcriptional regulation in breast cancer cell lines. Bioinformatics and functional analysis were performed to characterize transcriptional events specifically regulating CBX5 expression. TSA treatment and Chromatin Immunoprecipitation (ChIP) were performed to investigate the chromatin structure along CBX5 in breast cancer cells. Finally, expression of hnRNPA1 and CBX5 mRNA isoforms were measured by quantitative reverse transcriptase PCR (qRT-PCR) in breast cancer tissue samples. RESULTS: We demonstrate that an hnRNPA1 and CBX5 bi-directional core promoter fragment does not comprise intrinsic capacity for specific CBX5 down-regulation in metastatic cells. Characterization of transcriptional events in the 20 kb CBX5 intron 1 revealed existence of several novel CBX5 transcripts. Two of these encode consensus HP1α protein but used autonomous promoters in intron 1 by which HP1α expression could be de-coupled from the bi-directional promoter. In addition, another CBX5 transcriptional isoform, STET, was discovered. This transcript includes CBX5 exon 1 and part of intron 1 sequences but lacks inclusion of HP1α encoding exons. Inverse correlation between STET and HP1α coding CBX5 mRNA expression was observed in breast cancer cell lines and tissue samples from breast cancer patients. CONCLUSION: We find that HP1α is down-regulated in a mechanism involving CBX5 promoter downstream sequences and that regulation through alternative polyadenylation and splicing generates a transcript, STET, with potential importance in carcinogenesis.

ctDNA-based minimal residual disease detection in lung cancer patients treated with curative intended chemoradiotherapy using a clinically transferable approach.

BACKGROUND: Reliable biomarkers are needed to identify tumor recurrence of non-small cell lung cancer (NSCLC) patients after chemoradiotherapy (CRT) with curative intent. This could improve consolidation therapy of progressing patients. However, the approach of existing studies has limited transferability to the clinic. MATERIALS AND METHODS: A retrospective analysis of 135 plasma samples from 56 inoperable NSCLC patients who received CRT with curative intent was performed. Plasma samples collected at baseline, at the first check-up (average 1.6 months post-RT), and at the second check-up (average 4.5 months post-RT) were analyzed by deep sequencing with a commercially available cancer personalized profiling strategy (CAPP-Seq) using a tumor-agnostic approach. RESULTS: Detection of circulating tumor DNA (ctDNA) at 4.5 months after therapy was significantly associated with higher odds of tumor recurrence (OR: 5.4 (CI: 1.1-31), Fisher's exact test: p-value = 0.022), and shorter recurrence-free survival (RFS) (HR: 4.1 (CI: 1.7-10); log-rank test: p-value = 9e-04). In contrast, detection of ctDNA at 1.6 months after therapy was not associated with higher odds of tumor recurrence (OR: 2.7 (CI: 0.67-12), Fisher's exact test: p-value = 0.13) or shorter RFS (HR: 1.5 (CI: 0.67-3.3); log-rank test: p-value = 0.32). CONCLUSION: This study demonstrates that the detection of ctDNA can be used to identify minimal residual disease 4.5 months after CRT in NSCLC patients using a commercially available kit and a tumor-agnostic approach. Furthermore, the time point of collecting the plasma sample after CRT has decisive importance for the prognostic value of ctDNA. MICRO ABSTRACT: This study analysed 135 plasma samples from 56 NSCLC patients treated with curative intent chemoradiotherapy using a tumor-agnostic approach. Detecting ctDNA at 4.5 months post-treatment was linked to higher recurrence odds, indicating ctDNA's potential as a biomarker for identifying residual disease after treatment with curative intent. Importantly, the study emphasizes the importance of timing for accurate ctDNA analysis results.

Cell-free chromatin immunoprecipitation can determine tumor gene expression in lung cancer patients.

Cell-free DNA (cfDNA) in blood plasma can be bound to nucleosomes that contain post-translational modifications representing the epigenetic profile of the cell of origin. This includes histone H3 lysine 36 trimethylation (H3K36me3), a marker of active transcription. We hypothesised that cell-free chromatin immunoprecipitation (cfChIP) of H3K36me3-modified nucleosomes present in blood plasma can delineate tumour gene expression levels. H3K36me3 cfChIP followed by targeted NGS (cfChIP-seq) was performed on blood plasma samples from non-small-cell lung cancer (NSCLC) patients (NSCLC, n = 8), small-cell lung cancer (SCLC) patients (SCLC, n = 4) and healthy controls (n = 4). H3K36me3 cfChIP-seq demonstrated increased enrichment of mutated alleles compared with normal alleles in plasma from patients with known somatic cancer mutations. Additionally, genes identified to be differentially expressed in SCLC and NSCLC tumours had concordant H3K36me3 cfChIP enrichment profiles in NSCLC (sensitivity = 0.80) and SCLC blood plasma (sensitivity = 0.86). Findings here expand the utility of cfDNA in liquid biopsies to characterise treatment resistance, cancer subtyping and disease progression.

Genome-wide epigenetic and mRNA-expression profiling followed by CRISPR/Cas9-mediated gene-disruptions corroborate the MIR141/MIR200C-ZEB1/ZEB2-FGFR1 axis in acquired EMT-associated EGFR TKI-resistance in NSCLC cells.

Background: Epithelial-mesenchymal-transition (EMT) is an epigenetic-based mechanism contributing to the acquired treatment resistance against receptor tyrosine kinase inhibitors (TKIs) in non-small cell lung cancer (NSCLC) cells harboring epidermal growth factor receptor (EGFR)-mutations. Delineating the exact epigenetic and gene-expression alterations in EMT-associated EGFR TKI-resistance (EMT-E-TKI-R) is vital for improved diagnosis and treatment of NSCLC patients. Methods: We characterized genome-wide changes in mRNA-expression, DNA-methylation and the histone-modification H3K36me3 in EGFR-mutated NSCLC HCC827 cells in result of acquired EMT-E-TKI-R. CRISPR/Cas9 was used to functional examine key findings from the omics analyses. Results: Acquired EMT-E-TKI-R was analyzed with three omics approaches. RNA-sequencing identified 2,233 and 1,972 up- and down-regulated genes, respectively, and among these were established EMT-markers. DNA-methylation EPIC array analyses identified 14,163 and 7,999 hyper- and hypo-methylated, respectively, differential methylated positions of which several were present in EMT-markers. Finally, H3K36me3 chromatin immunoprecipitation (ChIP)-sequencing detected 2,873 and 3,836 genes with enrichment and depletion, respectively, and among these were established EMT-markers. Correlation analyses showed that EMT-E-TKI-R mRNA-expression changes correlated better with H3K36me3 changes than with DNA-methylation changes. Moreover, the omics data supported the involvement of the MIR141/MIR200C-ZEB1/ZEB2-FGFR1 signaling axis for acquired EMT-E-TKI-R. CRISPR/Cas9-mediated analyses corroborated the importance of ZEB1 in acquired EMT-E-TKI-R, MIR200C and MIR141 to be in an EMT-E-TKI-R-associated auto-regulatory loop with ZEB1, and FGFR1 to mediate cell survival in EMT-E-TKI-R. Conclusions: The current study describes the synchronous genome-wide changes in mRNA-expression, DNA-methylation, and H3K36me3 in NSCLC EMT-E-TKI-R. The omics approaches revealed potential novel diagnostic markers and treatment targets. Besides, the study consolidates the functional impact of the MIR141/MIR200C-ZEB1/ZEB2-FGFR1-signaling axis in NSCLC EMT-E-TKI-R.

Circulating cell-free HPV DNA is a strong marker for disease severity in cervical cancer.

For cervical cancer (CC), circulating cell-free HPV DNA (ccfHPV) may establish disease severity. Furthermore, HPV integration has been correlated to viral load and survival. In this study, pre-treatment plasma from 139 CC cases (50 primary surgery patients, 22 primary surgery + adjuvant oncological therapy patients, and 67 primary oncological therapy patients) was collected (2018-2020). Furthermore, plasma from 25 cervical intraepithelial neoplasia grade 3 patients and 15 healthy women (negative controls) were collected. Two next-generation sequencing (NGS) panels were used to establish ccfHPV presence and human papillomavirus type 16 (HPV16) integration status. ccfHPV was detected in four primary surgery (8.0%), eight primary surgery + adjuvant oncology (36.4%), and 54 primary oncology (80.6%) patients. For primary oncology patients with HPV16-related cancer (n = 37), more ccfHPVneg than ccfHPVpos patients had HPV16 integration (P = 0.04), and in patients with HPV16 integration (n = 13), ccfHPVpos patients had higher disease stages than ccfHPVneg patients (P = 0.05). In summary, ccfHPV presence is related to disease severity and may add to the debated Sedlis criteria used for identifying patients for adjuvant oncological therapy. However, ccfHPV detection is influenced by HPV integration status and disease stage, and these factors need to be considered in ccfHPVneg patients.

Analysis of circulating tumor DNA during checkpoint inhibition in metastatic melanoma using a tumor-agnostic panel.

Immunotherapy has revolutionized treatment of patients diagnosed with metastatic melanoma, where nearly half of patients receive clinical benefit. However, immunotherapy is also associated with immune-related adverse events, which may be severe and persistent. It is therefore important to identify patients that do not benefit from therapy early. Currently, regularly scheduled CT scans are used to investigate size changes in target lesions to evaluate progression and therapy response. This study aims to explore if panel-based analysis of circulating tumor DNA (ctDNA) taken at 3-week intervals may provide a window into the growing cancer, can be used to identify nonresponding patients early, and determine genomic alterations associated with acquired resistance to checkpoint immunotherapy without analysis of tumor tissue biopsies. We designed a gene panel for ctDNA analysis and sequenced 4-6 serial plasma samples from 24 patients with unresectable stage III or IV melanoma and treated with first-line checkpoint inhibitors enrolled at the Department of Oncology at Aarhus University Hospital, Denmark. TERT was the most mutated gene found in ctDNA and associated with a poor prognosis. We detected more ctDNA in patients with high metastatic load, which indicates that more aggressive tumors release more ctDNA into the bloodstream. Although we did not find evidence of specific mutations associated with acquired resistance, we did demonstrate in this limited cohort of 24 patients that untargeted, panel-based ctDNA analysis has the potential to be used as a minimally invasive tool in clinical practice to identify patients where the benefits of immunotherapy outweigh the drawbacks.

Tumoral PD-L1 does not impact time to treatment discontinuation in EGFR mutated non-small cell lung cancer patients treated with EGFR tyrosine kinase inhibitor-a Danish cohort study.

Background: Not all non-small cell lung cancer (NSCLC) patients harboring epidermal growth factor receptor (EGFR) mutations respond equally to therapy with tyrosine kinase inhibitors (TKIs). Programmed death ligand-1 (PD-L1) has previously been speculated as a possible biomarker for treatment outcome because of its positive correlation with these mutations in cell lines, but clinical studies have yielded conflicting results. We investigate the predictive potential of this surface protein in relation to clinical benefit in patients as measured by time to treatment discontinuation (TTD). Methods: We screened 516 Danish patients with EGFR mutations for inclusion based on a history of TKI treatment and a PD-L1 status that was assessed no earlier than three months prior to treatment initiation. Patients were stratified according to their expression of the potential biomarker as either negative (0%), low (1-49%) or high (≥50%). We employed the Kaplan-Meier method and the log rank test to test for a difference in treatment duration according to PD-L1 expression. Results: We included 111 Danish patients. The median follow-up time from inclusion until death or censoring at the end of the study was 670 days (range, 32-1,664 days, 95% CI: 502-897 days). Fifty-seven patients (51%) categorized as PD-L1 expression negative, 32 (29%) as low and 22 (20%) as high. We tested for differences in treatment duration between the three groups. Our tests did not yield statistically significant P values. Conclusions: In our cohort of 111 Danish patients with NSCLC harboring mutations in the epidermal growth factor receptor gene, expression levels of PD-L1 did not significantly impact the duration of clinical benefit from tyrosine kinase treatment.

Increased Soluble PD-1 Predicts Response to Nivolumab plus Ipilimumab in Melanoma.

BACKGROUND: Checkpoint inhibitors have revolutionized the treatment of metastatic melanoma, yielding long-term survival in a considerable proportion of the patients. Yet, 40-60% of patients do not achieve a long-term benefit from such therapy, emphasizing the urgent need to identify biomarkers that can predict response to immunotherapy and guide patients for the best possible treatment. Here, we exploited an unsupervised machine learning approach to identify potential inflammatory cytokine signatures from liquid biopsies, which could predict response to immunotherapy in melanoma. METHODS: We studied a cohort of 77 patients diagnosed with unresectable advanced-stage melanoma undergoing treatment with first-line nivolumab plus ipilimumab or pembrolizumab. Baseline and on-treatment plasma samples were tested for levels of PD-1, PD-L1, IFNγ, IFNß, CCL20, CXCL5, CXCL10, IL6, IL8, IL10, MCP1, and TNFα and analyzed by Uniform Manifold Approximation and Projection (UMAP) dimension reduction method and k-means clustering analysis. RESULTS: Interestingly, using UMAP analysis, we found that treatment-induced cytokine changes measured as a ratio between baseline and on-treatment samples correlated significantly to progression-free survival (PFS). For patients treated with nivolumab plus ipilimumab we identified a group of patients with superior PFS that were characterized by significantly higher baseline-to-on-treatment increments of PD-1, PD-L1, IFNγ, IL10, CXCL10, and TNFα compared to patients with worse PFS. Particularly, a high PD-1 increment was a strong individual predictor for superior PFS (HR = 0.13; 95% CI 0.034-0.49; p = 0.0026). In contrast, decreasing levels of IFNγ and IL6 and increasing levels of CXCL5 were associated with superior PFS in the pembrolizumab group, although none of the cytokines were individually predictors for PFS. CONCLUSIONS: In short, our study demonstrates that a high increment of PD-1 is associated with superior PFS in advanced-stage melanoma patients treated with nivolumab plus ipilimumab. In contrast, decreasing levels of IFNγ and IL6, and increasing levels of CXCL5 are associated with response to pembrolizumab. These results suggest that using serial samples to monitor changes in cytokine levels early during treatment is informative for treatment response.

An Extended PD-L2 Cytoplasmic Domain Results From Alternative Splicing in NSCLC Cells.

Antibody-based immunotherapy targeting the interaction between programmed cell death 1 (PD-1) and its ligand PD-L1 has shown impressive clinical outcomes in various cancer types, including nonsmall cell lung cancer (NSCLC). However, regulatory mechanisms in this immune checkpoint pathway still needs clarification. PD-L2 is structurally homologous to PD-L1 and is a second PD-1 ligand. Alternative mRNA splicing from the CD274 and PDCD1LG2 genes holds the potential to generate PD-L1 and PD-L2 isoforms, respectively, with novel functionality in regulation of the PD-1 immune checkpoint pathway. Here, we describe alternative splicing in NSCLC cells potentially generating eight different PD-L2 isoforms from the PDCD1LG2 gene. Extension of exon 6 by four nucleotides is the most prominent alternative splicing event and results in PD-L2 isoform V with a cytoplasmic domain containing a 10 amino acid extension. On average 13% of the PDCD1LG2 transcripts in NSCLC cell lines and 22% of the transcripts in NSCLC tumor biopsies encode PD-L2 isoform V. PD-L2 isoform V localizes to the cell surface membrane but less efficiently than the canonical PD-L2 isoform I. The cytoplasmic domains of PD-1 ligands can affect immune checkpoint pathways by conferring membrane localization and protein stability and thereby represent alternative targets for immunotherapy. In addition, cytoplasmic domains are involved in intracellular signalling cascades in cancer cells. The presented observations of different cytoplasmic domains of PD-L2 will be important in the future delineation of the PD-1 immune checkpoint pathway.

Osimertinib in non-small cell lung cancer with uncommon EGFR-mutations: a post-hoc subgroup analysis with pooled data from two phase II clinical trials.

Background: Osimertinib is standard of care for EGFR-mutated non-small cell lung cancer (NSCLC) patients. The efficacy of the drug in patients with mutations other than the common deletion in exon 19 and L858R in exon 21 is largely unknown. Methods: We identified patients with uncommon EGFR-mutations from two prospective clinical phase II, single-arm studies for previously treated patients and untreated patients, respectively, and pooled data for this analysis. All patients received treatment with osimertinib 80 mg daily until radiological progression or death. The primary endpoint of both trials was objective response rate (ORR), with progression-free survival (PFS), overall survival (OS) and intracranial efficacy as key secondary endpoints. Circulating tumour DNA (ctDNA) was analysed before and two weeks after treatment initiation in the first line cohort. Results: Of 299 enrolled patients in the two trials, 21 patients with uncommon mutations were identified; 12 patients had a single mutation (G719X or L861Q), one patient had L861Q and an exon 20 insertion, and 8 patients had compound mutations with G719X and either L861Q or S768I. Three of the 10 pretreated patients had the T790M resistance mutation. ORR was 47.6% and disease control rate (DCR) 85.7%. The median duration of response (DoR) was 7.9 months. Among 11 patients treated with osimertinib in first line, ORR was 63.6% vs. 30.0% of 10 previously treated patients. The median PFS was 5.5 months in both groups. Patients with G719X-compound mutations had a higher response rate (62.5% vs. 38.5%), a longer median PFS (13.7 vs. 3.5 months) and median OS (29.3 vs. 7.5 months) than patients with other mutations. Most first line treated patients (81.8%) displayed a reduction in ctDNA after two weeks of treatment. Conclusions: Osimertinib demonstrates activity in patients with uncommon EGFR-mutations, and especially for G719X-compound mutations.

The Diagnostic Value of Circulating Cell-Free HPV DNA in Plasma from Cervical Cancer Patients.

Circulating cell-free HPV DNA (ccfHPV DNA) may serve as a marker for cervical cancer. In this study, we used digital droplet PCR (ddPCR) to detect and quantify ccfHPV DNA in plasma from patients with HPV16- or HPV18-associated cervical cancer. Blood samples from 60 patients diagnosed with cervical cancer (FIGO IA1-IVA) at Aarhus or Odense University Hospital (June 2018 to March 2020) were collected prior to treatment, and patients were subdivided into an early stage (n = 30) and a late-stage subgroup (n = 30) according to disease stage. Furthermore, blood samples from eight women with HPV16- or 18-associated premalignant conditions (CIN3), and 15 healthy controls were collected. ddPCR was used to analyze plasma from all participants. ccfHPV DNA was detected in 19 late-stage patients (63.33%), 3 early stage patients (10.00%), and none of the CIN3 patients or controls. Quantitative evaluation showed significant correlations between ccfHPV DNA level and stage, tumor score, and tumor size. Thus, our results indicate that ccfHPV DNA may not be a useful marker for early detection of cervical cancer. However, for patients with advanced stage cervical cancer, ccfHPV DNA level represents a promising tool to establish tumor burden, making it useful for establishing treatment response and monitoring the disease.

Alectinib-Induced Pleural and Pericardial Effusions in ALK-Positive NSCLC.

Alectinib is the first-line targeted treatment for advanced ALK-positive non-small-cell lung cancer. Although it has a relatively mild toxicity profile, adverse events (AEs) do occur. We present a case of alectinib-induced bilateral pleural effusions and pericardial effusion that has not previously been reported. The patient developed severe dyspnea 3 months after starting alectinib. He underwent thorough clinical examination including evaluations of heart function. The heart function was normal. There was no sign of pneumonitis or progressive disease on the CT scans. Cytology samples of the pleural fluid from multiple thoracocenteses were examined and showed no malignant cells. Next-generation sequencing (NGS) analysis of circulating tumor DNA from sequential blood samples was also carried out. NGS identified no known driver mutations associated with the effusions. Hence, the effusions were suspected to be an alectinib-induced AE. Alectinib was withdrawn, and the patient commenced brigatinib. The effusions subsequently regressed.