Clinical implications of CSF-ctDNA positivity in newly diagnosed diffuse large B cell lymphoma.

The clinical implications of CSF-ctDNA positivity in newly diagnosed diffuse large B cell lymphoma (ND-DLBCL) remains largely unexplored. One hundred ND-DLBCL patients were consecutively enrolled as training cohort and another 26 ND-DLBCL patients were prospectively enrolled in validation cohort. CSF-ctDNA positivity (CSF(+)) was identified in 25 patients (25.0%) in the training cohort and 7 patients (26.9%) in the validation cohort, extremely higher than CNS involvement rate detected by conventional methods. Patients with mutations of CARD11, JAK2, ID3, and PLCG2 were more predominant with CSF(+) while FAT4 mutations were negatively correlated with CSF(+). The downregulation of PI3K-AKT signaling, focal adhesion, actin cytoskeleton, and tight junction pathways were enriched in CSF(+) ND-DLBCL. Furthermore, pretreatment CSF(+) was significantly associated with poor outcomes. Three risk factors, including high CSF protein level, high plasma ctDNA burden, and involvement of high-risk sites were used to predict the risk of CSF(+) in ND-DLBCL. The sensitivity and specificity of pretreatment CSF-ctDNA to predict CNS relapse were 100% and 77.3%. Taken together, we firstly present the prevalence and the genomic and transcriptomic landscape for CSF-ctDNA(+) DLBCL and highlight the importance of CSF-ctDNA as a noninvasive biomarker in detecting and monitoring of CSF infiltration and predicting CNS relapse in DLBCL.

Tumor mutational burden and efficacy of chemotherapy in lung cancer.

PURPOSE: TMB is one of the potent biomarkers of response to immune checkpoint blockade. The association between TMB and efficacy of chemotherapy in advanced lung cancer has not been comprehensively explored. METHODS: Ninety lung cancer patients receiving first-line chemotherapy with large panel next-generation sequencing data of pre-treatment tumor tissue were identified. The effect of TMB on PFS of chemotherapy were evaluated in univariate and multivariate analyses. RESULTS: The median TMB level of lung cancer patients enrolled in this study was 9.4 mutations/Mb, with TMB levels in smokers significantly higher than those in non-smokers. All patients were divided into high TMB and low TMB groups with the cutoff of the median TMB. The patients with low TMB had longer PFS of first-line chemotherapy (median PFS 9.77 vs 6.33 months, HR = 0.523, 95% CI 0.32-0.852, log-rank P = 0.009). Subgroup analysis showed that PFS of chemotherapy favored low TMB than high TMB among subgroups of male, age < 60, NSCLC, adenocarcinoma, stage IV, ECOG PS 0, driver mutation positive, TP53 wild type and patients not receiving bevacizumab. In multivariate analysis, PFS of chemotherapy remained significantly longer in low TMB group (HR = 0.554, p = 0.036). In those patients received immunotherapy upon unsatisfactory chemotherapy, PFS of immunotherapy was much longer in high TMB group (median PFS 32.88 vs 6.62 months, HR = 0.2426, 95% CI 0.06-0.977, log-rank P = 0.04). CONCLUSIONS: TMB level of tumor tissue is a potent biomarker for efficacy of chemotherapy and immunotherapy in lung cancer. It may provide some clues for the decision of treatment strategy.

Rechallenge of immune checkpoint inhibitors in a case with adverse events inducing myasthenia gravis.

The mechanism(s) of immune checkpoint inhibitor (ICI)-induced myasthenia gravis (MG), an immune-related adverse event (irAE) that is fatal and limits subsequent ICI use, remain unexplored. Here, through comparative genomic analysis, we identified a pathogenic p.S467C germline variant in SLC22A5 in a thymoma case with ICI-induced MG, which was found to be associated with fatty acid oxidation through its regulation on L-carnitine levels. Remarkably, ICI rechallenge with L-carnitine pretreatment led to durable response without MG-related symptoms. Thus, we provide the first clinical evidence of genetic test-directed irAE management, which integrates individualized ICI treatment into the evolving paradigm of cancer management.

Unique genomic alterations of cerebrospinal fluid cell-free DNA are critical for targeted therapy of non-small cell lung cancer with leptomeningeal metastasis.

We reported unique molecular features of cerebrospinal fluid (CSF) of NSCLC patients with leptomeningeal metastasis (LM), suggesting to establish CSF as a better liquid biopsy in clinical practices. We performed next-generation panel sequencing of primary tumor tissue, plasma and CSF from 131 NSCLC patients with LM, and observed high somatic copy number variations (CNV) in CSF of NSCLC patients with LM. The status of EGFR-activating mutations was highly concordant between CSF, plasma, and primary tumors. ALK translocation was detected in 8.3% of tumor tissues, but only 2.4% in CSF and 2.7% in plasma. Others such as ROS1 rearrangement, RET fusion, HER2 mutation, NTRK1 fusion, and BRAF V600E mutation were detected in 7.9% of CSF and 11.1% of tumor tissues, but only 4% in plasma. Our study has shed light on the unique genomic variations of CSF and demonstrated that CSF may represent better liquid biopsy for NSCLC patients with LM.

Unique Genomic Alterations of Cerebrospinal Fluid Cell-Free DNA Are Critical for Targeted Therapy of Non-Small Cell Lung Cancer With Leptomeningeal Metastasis.

We reported unique molecular features of cerebrospinal fluid (CSF) of nonsmall cell lung cancer (NSCLC) patients with leptomeningeal metastasis (LM), suggesting establishing CSF as a better liquid biopsy in clinical practices. We performed next-generation panel sequencing of primary tumor tissue, plasma, and CSF from 131 NSCLC patients with LM and observed high somatic copy number variations (CNV) in CSF of NSCLC patients with LM. The status of EGFR-activating mutations was highly concordant between CSF, plasma, and primary tumors. ALK translocation was detected in 8.3% of tumor tissues but only 2.4% in CSF and 2.7% in plasma. Others such as ROS1 rearrangement, RET fusion, HER2 mutation, NTRK1 fusion, and BRAF V600E mutation were detected in 7.9% of CSF and 11.1% of tumor tissues but only 4% in plasma. Our study has shed light on the unique genomic variations of CSF and demonstrated that CSF might represent better liquid biopsy for NSCLC patients with LM.

Abnormal B-cell development in TIMP-deficient bone marrow.

Bone marrow (BM) is the primary site of hematopoiesis and is responsible for a lifelong supply of all blood cell lineages. The process of hematopoiesis follows key intrinsic programs that also integrate instructive signals from the BM niche. First identified as an erythropoietin-potentiating factor, the tissue inhibitor of metalloproteinase (TIMP) protein family has expanded to 4 members and has widely come to be viewed as a classical regulator of tissue homeostasis. By virtue of metalloprotease inhibition, TIMPs not only regulate extracellular matrix turnover but also control growth factor bioavailability. The 4 mammalian TIMPs possess overlapping enzyme-inhibition profiles and have never been studied for their cumulative role in hematopoiesis. Here, we show that TIMPs are critical for postnatal B lymphopoiesis in the BM. TIMP-deficient mice have defective B-cell development arising at the pro-B-cell stage. Expression analysis of TIMPless hematopoietic cell subsets pointed to an altered B-cell program in the Lineage-Sca-1+c-Kit+ (LSK) cell fraction. Serial and competitive BM transplants identified a defect in TIMP-deficient hematopoietic stem and progenitor cells for B lymphopoiesis. In parallel, reverse BM transplants uncovered the extrinsic role of stromal TIMPs in pro- and pre-B-cell development. TIMP deficiency disrupted CXCL12 localization to LepR+ cells, and increased soluble CXCL12 within the BM niche. It also compromised the number and morphology of LepR+ cells. These data provide new evidence that TIMPs control the cellular and biochemical makeup of the BM niche and influence the LSK transcriptional program required for optimal B lymphopoiesis.

Alterations of circulating bacterial DNA in colorectal cancer and adenoma: A proof-of-concept study.

The gut microbiota is closely associated with colorectal neoplasia. While most metagenomics studies utilized fecal samples, circulating bacterial DNA in colorectal neoplasia patients remained unexplored. This proof-of-concept study aims to characterize alterations of circulating bacterial DNA in colorectal neoplasia patients. We performed WGS of plasma samples from 25 colorectal cancer (CRC) patients, 10 colorectal adenoma (CRA) patients and 22 healthy controls (HC). Bacterial relative abundance was measured by removing the host genome and mapping reads into bacterial genomes. By diversity analysis, we found plasma samples required less sample size to approach saturation than fecal samples, and species diversity in HC was slightly higher compared with CRC/CRA patients. The majority of circulating bacterial DNA came from bacterial genera which commonly associated with gastrointestine and oral tract. By differential analysis, a total of 127 significant species between CRC patients and HC were identified, on which basis 28 species with top predictive ability were selected and showed promise in preliminary discrimination between CRC/CRA and HC. In CRA patients, relative abundance of the selected 28 species more closely resembled those in CRC patients than HC. By comparing with fecal metagenomics studies, we found there was moderate positive correlation between fold changes of the overlapped fecal and circulating bacterial DNA. Finally, species correlation analysis revealed that CRC and HC displayed distinct patterns of species association. In conclusion, this study demonstrated alterations of circulating bacterial DNA in colorectal neoplasia patients, which had the potential to become non-invasive biomarkers for colorectal neoplasia screening and early diagnosis.

Genetic aberrations in Chinese pancreatic cancer patients and their association with anatomic location and disease outcomes.

OBJECTIVES: Pancreatic cancer (PC) is one of the most lethal malignancies with an increasing death rate over the years. We performed targeted sequencing and survival analyses on 90 Chinese pancreatic cancer patients, hoping to identify genomic biomarkers associated with clinical outcomes and therapeutic options. METHOD: Genomic DNA was extracted from formalin-fixed paraffin-embedded (FFPE) tissue specimens of 90 pancreatic cancer patients and sequenced. The associations with clinicopathological factors were analyzed. RESULT: High prevalence of driver mutations in KRAS, TP53, CDKN2A, SMAD4, and ARID1A genes were found. Most mutated genes in PC belonged to cell cycle and DNA damage repair pathways. Tumors that arise from the pancreas' body and tail (BT tumors) displayed a higher ratio of mutated KRAS and TP53 than those that arise from the pancreas' head and neck (HN tumors), who showed less diverse KRAS subtypes. Patients with a KRAS p.G12R mutated tumor tended to have a prolonged disease-free survival (DFS) and overall survival (OS) than other KRAS subtypes. Those with an altered ARID1A gene and more than two mutated driver genes tended to have a shorter DFS and OS. CONCLUSION: HN and BT tumors of the pancreas displayed different mutational profiles, which had prognostic significances and indicated different potential therapeutic options.

Metagenomic Next-Generation Sequencing of Cerebrospinal Fluid for the Diagnosis of External Ventricular and Lumbar Drainage-Associated Ventriculitis and Meningitis.

Metagenomic next-generation sequencing (mNGS) has become a widely used technology that can accurately detect individual pathogens. This prospective study was performed between February 2019 and September 2019 in one of the largest clinical neurosurgery centers in China. The study aimed to evaluate the performance of mNGS on cerebrospinal fluid (CSF) from neurosurgical patients for the diagnosis of external ventricular and lumbar drainage (EVD/LD)-associated ventriculitis and meningitis (VM). We collected CSF specimens from neurosurgical patients with EVD/LD for more than 24 h to perform conventional microbiological studies and mNGS analyses in a pairwise manner. We also investigated the usefulness of mNGS of CSF for the diagnosis of EVD/LD-associated VM. In total, 102 patients were enrolled in this study and divided into three groups, including confirmed VM (cVM) (39), suspected VM (sVM) (49), and non-VM (nVM) (14) groups. Of all the patients, mNGS detected 21 Gram-positive bacteria, 20 Gram-negative bacteria, and five fungi. The three primary bacteria detected were Staphylococcus epidermidis (9), Acinetobacter baumannii (5), and Staphylococcus aureus (3). The mNGS-positive coincidence rate of confirmed EVD/LD-associated VM was 61.54% (24/39), and the negative coincidence rate of the nVM group was 100% (14/14). Of 15 VM pathogens not identified by mNGS in the cVM group, eight were negative with mNGS and seven were inconsistent with the conventional microbiological identification results. In addition, mNGS identified pathogens in 22 cases that were negative using conventional methods; of them, 10 patients received a favorable clinical treatment; thus, showing the benefit of mNGS-guided therapy.

Durable Complete Response to Alectinib in a Lung Adenocarcinoma Patient With Brain Metastases and Low-Abundance EML4-ALK Variant in Liquid Biopsy: A Case Report.

EML4-ALK fusions are targetable oncogenic drivers in a subset of advanced non-small cell lung cancer (NSCLC) patients that can benefit from selected ALK inhibitors. Precise detection of ALK fusions may yield critical information for selection of appropriate therapy and hence improve patient survival. Analysis of circulating tumor DNA (ctDNA) in liquid biopsies using next generation sequencing (NGS) prior to or during treatment hold great promise for disease monitoring and treatment guidance of various cancers including NSCLC. Herein, we report a case of a 21-year-old advanced lung adenocarcinoma patient with a low abundance (0.03%) of EML4-ALK rearrangement identified in plasma ctDNA upon progression on two lines of chemotherapy that demonstrated long-term complete response to alectinib (>13 months) including metastatic brain tumors. Patient's clinical and pathologic characteristics, computerized tomography (CT) scans and brain magnetic resonance imaging (MRI) were reviewed retrospectively. Taken together, our report not only reinforces the translational utility of NGS-based genomic sequencing of liquid biopsy in guiding clinical practice, but also highlights the superior efficacy of alectinib than chemotherapy in ALK+ NSCLC with brain metastases, albeit at a low variant allele abundance.

EML4-ALK, a potential therapeutic target that responds to alectinib in ovarian cancer.

Ovarian cancer is prone to recurrence and chemotherapy resistance. Ovarian tumours of some patients have been positive for anaplastic lymphoma kinase fusion gene expression (ALK+). Preclinical studies indicate that anaplastic lymphoma kinase inhibitor can suppress the growth of ovarian cancer cells and transplantation tumours. Here, we present a patient with metastatic ALK+ high-grade serous ovarian cancer that testing positive for EML4-ALK (microtubule-associated protein-like 4 gene, fused to the anaplastic lymphoma kinase gene), experienced dramatic benefit after administration of the anaplastic lymphoma kinase inhibitor alectinib. This is the first clinical evidence that treatment with alectinib may provide a personalized maximum benefit for patients with high-grade serous ovarian cancer who are positive for EML4-ALK.

Quantitative characterization of tumor cell-free DNA shortening.

BACKGROUND: Previous studies found that cell-free DNA (cfDNA) generated from tumors was shorter than that from healthy cells, and selecting short cfDNA could enrich for tumor cfDNA and improve its usage in early cancer diagnosis and treatment monitoring; however, the underlying mechanism of shortened tumor cfDNA was still unknown, which potentially limits its further clinical application. RESULTS: Using targeted sequencing of cfDNA in a large cohort of solid tumor patient, sequencing reads harboring tumor-specific somatic mutations were isolated to examine the exact size distribution of tumor cfDNA. For the majority of studied cases, 166 bp remained as the peak size of tumor cfDNA, with tumor cfDNA showing an increased proportion of short fragments (100-150 bp). Less than 1% of cfDNA samples were found to be peaked at 134/144 bp and independent of tumor cfDNA purity. Using whole-genome sequencing of cfDNA, we discovered a positive correlation between cfDNA shortening and the magnitude of chromatin inaccessibility, as measured by transcription, DNase I hypersensitivity, and histone modifications. Tumor cfDNA shortening occurred simultaneously at both 5' and 3' ends of the DNA wrapped around nucleosomes. CONCLUSIONS: Tumor cfDNA shortening exhibited two distinctive modes. Tumor cfDNA purity and chromatin inaccessibility were contributing factors but insufficient to trigger a global transition from 166 bp dominant to 134/144 bp dominant phenotype.

Undetectable circulating tumor DNA levels correlate with low risk of recurrence/metastasis in postoperative pathologic stage I lung adenocarcinoma patients.

OBJECTIVES: The application of circulating tumor DNA (ctDNA) monitoring after resection in pathologic(p) stage I lung adenocarcinoma (LUAD) patients remains controversial and it is of great clinical interest to decipher the difference of genetic features between ground-glass opacity (GGO) and solid nodules (non-GGO) subgroups. We aim to assess the utility of ctDNA in tracking early recurrence or metastasis following surgery and reveal the genetic differences between GGO and non-GGO. MATERIALS AND METHODS: Tumor tissues and matched postoperative plasma samples were collected from a total of 82 (p)stage I LUAD patients. Comprehensive genomic profiling was performed using capture-based hybrid next generation sequencing by targeting 422 cancer relevant genes. RESULTS: EGFR and TP53 represent commonly mutated genes in this cohort of (p)stage I lung adenocarcinoma, followed by alterations in ALK, PIK3CA, STK11 and MYC. For a median follow-up period of 22.83 months after surgery, 65 out of 67 ctDNA-negative patients remained progression-free, while 3 out of 15 ctDNA-positive patients progressed [P = 0.040; positive predictive value = 0.20, 95 % confidence interval (CI), 0.04-0.48; negative predictive value = 0.97, 95 % CI, 0.9-1]. With time-dependent Cox regression analysis, we observed that ctDNA positivity significantly correlated with increased probability of early tumor recurrence or metastasis (P = 0.02, HR=8.5). Further comparison between GGO and non-GGO subgroups indicated the frequency of TP53 mutations in non-GGO was markedly higher than that in GGO (47 % vs 21 %, P < 0.05). Pathway analysis showed the epigenetic regulation pathway was more frequently affected in GGO subgroup, while impaired apoptosis/cell cycle pathway was more enriched in non-GGO LUADs. CONCLUSIONS: Our longitudinal ctDNA monitoring data showed that undetectable ctDNA may predict low risk of tumor recurrence or metastasis in postoperative (p)stage I LUAD patients, while it requires further investigation on how robust the positive ctDNA results could predict tumor relapse in these patients. CLINICAL REGISTRATION NUMBER: NCT03172156.

Primary pulmonary lymphoepithelioma-like carcinoma is characterized by high PD-L1 expression, but low tumor mutation burden.

Primary pulmonary lymphoepithelioma-like carcinoma (PLELC) is a rare subtype of non-small cell lung cancer (NSCLC). There are few reported studies on the relationship between programmed death ligand-1 (PD-L1) expression and genomics features of this distinct NSCLC subtype. Our study aimed to investigate the expression levels of PD-L1 to determine their clinical value and to identify genetic alterations in PLELC. Fifty-nine PLELC patients, whose clinical information and pathology results were available, were included in this study. Immunohistochemical analysis of PD-L1 was performed in all cases. Specimens of 37 PLELCs and 3 metastatic nasopharyngeal carcinomas (NPCs) of the lung, resected within the previous 3 years, were chosen for mutation analysis, using next-generation sequencing of 425 genes. PLELC patients in the present study were mainly non-smoking females, with a high frequency of PD-L1 positivity in their tumors. Positivity rates were 96.6 %, 91.5 %, 83.1 %, and 61.0 % at tumor proportion scores (TPSs)≥ 1%, 5%, 10 %, and 50 %, respectively. Moreover, we observed that PD-L1 expression was higher in specimens stored for ≤ 3 years and in tumor cells with vesicular nucleus morphology at a TPS ≥ 50 %. Mutation analysis suggested a relatively high frequency of TP53 mutations and MCL1 copy number variation, but low tumor mutation burden (TMB) (ranging from 0 to 6.9, median of 1.1 mutation per megabase) and similarity of gene alteration with NPCs. However, no specific germline mutation was detected in PLELC patients. Additionally, survival analysis showed that patients in the early stages (stage I and II) had higher progression-free survival rates (P = 0.035) and those with tumors containing obvious stroma fibrosis tended to have worse prognosis (P =  0.008). However only stage was shown to be the independent prognostic factor (P = 0.008, HR=4.807, 95 %CI:1.508-15.323).PLELC is a subtype of lung cancer with distinct clinicopathological and genetic features, especially characterized by high PD-L1 expression and low TMB.

Clinical and molecular characteristics of Chinese non-small cell lung cancer patients with ERBB2 transmembrane domain mutations.

Transmembrane domain (TMD) mutations of ERBB2 have previously been reported in lung cancer patients in addition to well-studied kinase domain (KD) mutations, which may stabilize ERBB2 heterodimerization with other EGFR family members and favor a kinase active conformation. However, the frequency and clinical significance of ERBB2 TMD mutations in Chinese population is unknown. We prospectively analyzed the next-generation sequencing data of 34 368 Chinese lung cancer patients with different sample types, including tumor tissue, plasma, cerebrospinal fluid, and pleural effusion. Patients' clinical characteristics and treatment history were retrieved from the database for further evaluation. Our findings show that ERBB2 V659/G660 mutations were detected at a frequency of 0.13% (45/34 368), of which the most frequent was V659D/E (88.9%), with a trend in nonsmokers and male. Moreover, 18% of patients (8/45) showed EGFR and/or ERBB2 amplification, whereas nine patients presented EGFR L858R or exon19 deletion. Interestingly, novel ERBB3 TMD mutation I646R was found coexisting in three patients with ERBB2 V659D and one patient with ERBB2 G660D, which might influence its heterodimerization with ERBB2 and further activate ERBB2. Four ERBB2 TMD mutation-positive patients received afatinib monotherapy or combination therapy, but showed variable responses. One patient with V659E responded well to ERBB2 inhibitor lapatinib plus capecitabine as well as subsequent afatinib treatment upon progression. Our study provides valuable insights into the distribution of ERBB2 TMD mutations by employing the largest Asian lung cancer cohort thus far. Patients with ERBB2 TMD mutations who received afatinib, a pan-ERBB inhibitor, demonstrated mixed responses, posing the urgent need to develop more effective therapeutic strategy for patients who carry ERBB2 TMD mutations.

Variability of EGFR exon 20 insertions in 24 468 Chinese lung cancer patients and their divergent responses to EGFR inhibitors.

EGFR exon 20 insertions (EGFR e20ins) account for up to 10% of EGFR mutations in lung cancer; however, tumors with EGFR e20ins had poor response rates to EGFR tyrosine kinase inhibitors (TKIs) including gefitinib, erlotinib, afatinib, and osimertinib, and the heterogeneity of EGFR e20ins further complicates the clinical studies. Here, we retrospectively screened next-generation sequencing (NGS) data from 24 468 lung cancer patients, and a total of 85 unique EGFR e20ins variants were identified in 547 cases (2.24%), with p.A767_V769dup (25.1%) and p.S768_D770dup (17.6%) being the most prevalent ones. Comprehensive genomic profiling revealed that TP53 mutations frequently coexisted with p.H773dup (77.8%, P = 0.0558) and p.A767_V769dup (62.8%, P = 0.0325), while RB1 mutations usually co-occurred with p.H773_V774insAH (33.3%, P = 0.0551), implying that different EGFR e20ins variants might require distinct genomic context for tumorigenesis and/or maintenance. Despite that treatment regimens were highly diverse for EGFR e20ins-positive patients, we observed an overall response rate of 14% and a disease control rate (DCR) of 38.4% in 65 patients who received at least one EGFR TKI. The progression-free survival (PFS) differs significantly in six representative EGFR e20ins variants (P = 0.017), and EGFR p.A763_Y764insFQEA was associated with better PFS than other EGFR e20ins when treating with various EGFR TKIs. Some EGFR e20ins variants showed at least partial response to first-generation EGFR TKIs, including p.A767_V769dup, p.S768_D770dup, p.N771_H773dup, p.A763_Y764insFQEA, and p.D770_N771insG. Poziotinib achieved higher DCR for p.S768_D770dup than for p.A767_V769dup, whereas osimertinib showed limited effects for these two insertions when used as the first-line treatment. Overall, our results demonstrated that EGFR e20ins were highly diversified in terms of insertion patterns and co-occurring mutations and these EGFR e20ins variants showed different clinical responses to various EGFR TKIs, suggesting the clinical importance of selecting proper EGFR TKI treatment based on the specific EGFR e20ins type.

Wait-and-See Treatment Strategy Could be Considered for Lung Adenocarcinoma with Special Pleural Dissemination Lesions, and Low Genomic Instability Correlates with Better Survival.

BACKGROUND: This study aimed to evaluate the feasibility of a wait-and-see strategy for non-small cell lung cancer (NSCLC) patients with special pleural dissemination lesions (r-pM1a and s-pM1a). Furthermore, the study characterized genomic alternations about disease progression. METHODS: For this study, 131 NSCLC patients with a diagnosis of pM1a were retrospectively selected. Survival differences were evaluated among patients treated with three different initial postoperative treatments: chemotherapy, targeted therapy, and wait-and-see strategy. Whole-exome sequencing (WES) was performed on primary and metastatic tumors of 10 patients with dramatic progression and 13 patients with gradual progression. RESULTS: The wait-and-see group showed better progression-free survival (PFS) than the chemotherapy group (p < 0.001) but PFS similar to that of targeted group (p = 0.984). This pattern persisted in epidermal growth factor receptor (EGFR)-positive patients. For patients with EGFR-negative/unknown status, PFS was longer in the wait-and-see group than in the two treatment groups. Furthermore, better overall survival (OS) was observed for the patients who received chemotherapy or targeted therapy after the wait-and-see strategy than for those who received chemotherapy or targeted therapy immediately. Lymph node status was an independent prognostic factor for PFS and OS. Finally, WES analysis showed that a high genomic instability index (GIS) and chromosome 18q loss were more common in metastatic tumors, and low GIS was significantly associated with better PFS (p = 0.016). CONCLUSIONS: The wait-and-see strategy could be considered for special pM1a patients without lymph nodes metastasis, and patients with a low GIS may be suitable for this strategy.

Acquired multiple secondary BRCA2 mutations upon PARPi resistance in a metastatic pancreatic cancer patient harboring a BRCA2 germline mutation.

PARP inhibitor (PARPi) therapies have been approved for treating multiple germline BRCA mutated (gBRCAm) advanced cancers including metastatic pancreatic cancer. Although significantly prolonged progression-free survival was observed in gBRCAm pancreatic cancer patients, there was no improved overall survival. The underlined resistant mechanism to PARPi therapy is worth pursuing. Here, we reported a patient with advanced pancreatic cancer harboring a germline deleterious BRCA2 V1804Kfs mutation as well as somatic mutations in KRAS, TP53 and PTEN. Stable disease was achieved with the combination therapy of cisplatin and PARPi olaparib, but the disease quickly progressed after 18 weeks of treatment. Next-generation sequencing (NGS)-based genomic profiling of the liver metastasis and liquid biopsy revealed four newly acquired BRCA2 indel mutations, including two reversion mutations that could potentially restore BRCA2 function in the PARPi-resistant tumor. Our case showed that although initial response to PARPi therapy can be achieved in advanced gBRCAm pancreatic cancer patient, the tumor rapidly evolved to acquire multiple secondary BRCA2 mutations to restore the integrity of DNA repair and confer drug resistance, which may contribute to the unimproved overall survival in pancreatic cancer patients.