Singlet oxygen-based photoelectrochemical detection of single-point mutations in the KRAS oncogene

Single nucleotide point mutations in the KRAS oncogene occur frequently in human cancers, rendering them intriguing targets for diagnosis, early detection and personalized treatment. Current detection methods are based on polymerase chain reaction, sometimes combined with next-generation sequencing, which can be expensive, complex and have limited availability. Here, we propose a novel singlet oxygen (1O2)-based photoelectrochemical detection methodology for single-point mutations, using KRAS mutations as a case study. This detection method combines the use of a sandwich assay, magnetic beads and robust chemical photosensitizers, that need only air and light to produce 1O2, to ensure high specificity and sensitivity. We demonstrate that hybridization of the sandwich hybrid at high temperatures enables discrimination between mutated and wild-type sequences with a detection rate of up to 93.9%. Additionally, the presence of background DNA sequences derived from human cell-line DNA, not containing the mutation of interest, did not result in a signal, highlighting the specificity of the methodology. A limit of detection as low as 112 pM (1.25 ng/mL) was achieved without employing any amplification techniques. The developed 1O2-based photoelectrochemical methodology exhibits unique features, including rapidity, ease of use, and affordability, highlighting its immense potential in the field of nucleic acid-based diagnostics.

The Quest for Circulating Biomarkers in Neuroendocrine Neoplasms: a Clinical Perspective

OPINION STATEMENT

Given the considerable heterogeneity in neuroendocrine neoplasms (NENs), it appears unlikely that a sole biomarker exists capable of fully capturing all useful clinical aspects of these tumors. This is reflected in the abundant number of biomarkers presently available for the diagnosis, prognosis, and monitoring of NEN patients. Although assessment of immunohistochemical and radiological markers remains paramount and often obligatory, there has been a notable surge of interest in circulating biomarkers over the years given the numerous benefits associated with liquid biopsies. Currently, the clinic primarily relies on single-analyte assays such as the chromogranin A assay, but these are far from ideal because of limitations such as compromised sensitivity and specificity as well as a lack of standardization. Consequently, the quest for NEN biomarkers continued with the exploration of multianalyte markers, exemplified by the development of the NETest and ctDNA-based analysis. Here, an extensive panel of markers is simultaneously evaluated to identify distinct signatures that could enhance the accuracy of patient diagnosis, prognosis determination, and response to therapy prediction and monitoring. Given the promising results, the development and implementation of these multianalyte markers are expected to usher in a new era of NEN biomarkers in the clinic. In this review, we will outline both clinically implemented and more experimental circulating markers to provide an update on developments in this rapidly evolving field.

Preoperative treatment with mFOLFIRINOX or Gemcitabine/Nab-paclitaxel +/- isotoxic high-dose stereotactic body Radiation Therapy (iHD-SBRT) for borderline resectable pancreatic adenocarcinoma (the STEREOPAC trial): study protocol for a randomised comparative multicenter phase II trial

BACKGROUND

For patients with pancreatic ductal adenocarcinoma (PDAC), surgical resection remains the only potentially curative treatment. Surgery is generally followed by postoperative chemotherapy associated with improved survival, yet neoadjuvant therapy is a rapidly emerging concept requiring to be explored and validated in terms of treatment options and oncological outcomes. In this context, stereotactic body radiation (SBRT) appears feasible and can be safely integrated into a neoadjuvant chemotherapy regimen of modified FOLFIRINOX (mFFX) with promising benefits in terms of R0 resection, local control and survival. However, the optimal therapeutic sequence is still not known, especially for borderline resectable PDAC, and the role of adding SBRT to chemotherapy in the neoadjuvant setting needs to be evaluated in randomised controlled trials. The aim of the STEREOPAC trial is to assess the impact and efficacy of adding isotoxic high-dose SBRT (iHD-SBRT) to neoadjuvant mFFX or Gemcitabine/Nab-Paclitaxel (Gem/Nab-P) in patients with borderline resectable PDAC.

METHODS

This is a randomised comparative multicentre phase II trial, planning to enrol patients (n = 256) diagnosed with a borderline resectable biopsy-confirmed PDAC. Patients will receive 4 cycles of mFFX (or 6 doses of Gem/Nab-P). After full disease restaging, non-progressive patients will be randomised for receiving either 4 additional mFFX cycles (or 6 doses of Gem/Nab-P) (Arm A), or 2 mFFX cycles (or 3 doses of Gem/Nab-P) + iHD-SBRT (35 to 55 Gy in 5 fractions) + 2 mFFX cycles (or 3 doses of Gem/Nab-P) (Arm B). Then curative surgery will be performed followed by adjuvant chemotherapy according to patient's condition. The co-primary endpoints are R0 resection and disease-free survival after the complete sequence strategy. The secondary endpoints include resection rate, overall survival, locoregional failure / distant metastasis free interval, pathologic complete response, toxicity, postoperative complications and quality of life assessment.

DISCUSSION

This trial will help define the best neoadjuvant treatment sequence for borderline resectable PDAC and aims to evaluate if a total neoadjuvant treatment integrating iHD-SBRT improves the patients' oncological outcomes.

TRIAL REGISTRATION

The study was registered at ClinicalTrails.gov (NCT05083247) on October 19th, 2021, and in the Clinical Trials Information System (CTIS) EU CT database (2022-501181-22-01) on July 2022.

Novel therapeutic strategies in pancreatic cancer: moving beyond cytotoxic chemotherapy

INTRODUCTION

Prognosis of patients with metastatic pancreatic ductal adenocarcinoma (mPDAC) remains disappointing with a 5-year overall survival of only 3-5%. Compared to other cancers, the evolution in standard therapeutic options has been stagnant and polychemotherapy regimens (with well-known toxicity profile and resistance pattern) remain standard of care. Only for patients (5%-7%) with a breast cancer gene (BRCA) pathogenic germline variant, prognosis has improved by the use of olaparib (poly-ADP ribose polymerase (PARP) inhibitor).

AREAS COVERED

This review covers emerging treatment strategies in the management of mPDAC. One of the main topics is the rigid and immunological cold tumor microenvironment (TME) of PDAC and the search for agents that impact this TME and/or engage the immune system. In addition, the use of next-generation sequencing (NGS) has elicited for some patients new targeted therapies directed at alterations in the RTK/RAS/MAPK pathway and the deoxyribonucleic acid (DNA) damage repair pathway. Other evolving treatment strategies are also discussed.

EXPERT OPINION

The search for new, often combination, treatment strategies for mPDAC should be encouraged and implemented in early treatment lines given the significant decline of performance status of patients in later lines. NGS analysis should be used where available, although cost-effectiveness could be debatable.

Prospective comparison of [18F]AlF-NOTA-octreotide PET/MRI to [68Ga]Ga-DOTATATE PET/CT in neuroendocrine tumor patients

BACKGROUND

Fluorine-18-labeled SSAs have the potential to become the next-generation tracer in SSTR-imaging in neuroendocrine tumor (NET) patients given their logistical advantages over the current gold standard gallium-68-labeled SSAs. In particular, [18F]AlF-OC has already shown excellent clinical performance. We demonstrated in our previous report from our prospective multicenter trial that [18F]AlF-OC PET/CT outperforms [68Ga]Ga-DOTA-SSA, but histological confirmation was lacking due to ethical and practical reasons. In this second arm, we therefore aimed to provide evidence that the vast majority of [18F]AlF-OC PET lesions are in fact true NET lesions by analyzing their MR characteristics on simultaneously acquired MRI. We had a special interest in lesions solely detected by [18F]AlF-OC ("incremental lesions").

METHODS

Ten patients with a histologically confirmed neuroendocrine tumor (NET) and a standard-of-care [68Ga]Ga-DOTATATE PET/CT, performed within 3 months, were prospectively included. Patients underwent a whole-body PET/MRI (TOF, 3 T, GE Signa), 2 hours after IV injection of 4 MBq/kg [18F]AlF-OC. Positive PET lesions were evaluated for a corresponding lesion on MRI. The diagnostic performance of both PET tracers was evaluated by determining the detection ratio (DR) for each scan and the differential detection ratio (DDR) per patient.

RESULTS

In total, 195 unique lesions were detected: 167 with [68Ga]Ga-DOTATATE and 193 with [18F]AlF-OC. The DR for [18F]AlF-OC was 99.1% versus 91.4% for [68Ga]Ga-DOTATATE, significant for non-inferiority testing (p = 0.0001). Out of these 193 [18F]AlF-OC lesions, 96.2% were confirmed by MRI to be NET lesions. Thirty-three incremental lesions were identified by [18F]AlF-OC, of which 91% were confirmed by MRI and considered true positives.

CONCLUSION

The DR of [18F]AlF-OC was numerically higher and non-inferior to the DR of [68Ga]Ga-DOTATATE. [18F]AlF-OC lesions and especially incremental lesions were confirmed as true positives by MRI in more than 90% of lesions. Taken together, these data further validate [18F]AlF-OC as a new alternative for SSTR PET in clinical practice. Trial registration ClinicalTrials.gov: NCT04552847. Registered 17 September 2020, https://beta.

CLINICALTRIALS

gov/study/NCT04552847.

New Developments in Treating RAS-Mutated Metastatic Colorectal Cancer

OPINION STATEMENT

One of the great challenges in digestive oncology is choosing the optimal therapy for RAS-mutated metastatic colorectal cancer (mCRC). Even though the RAS genes and accompanying pathway were identified decades ago and extensive knowledge exists on their role in carcinogenesis, it has proven challenging to translate these insights into new therapies and clinical benefit for patients. However, recently, new drugs targeting this pathway (for example, KRAS^G12C inhibitors) have shown promising results in clinical trials, as monotherapy or in combination regimens. Although resistance remains an important issue, more knowledge on adaptive resistance and feedback loops in the RAS-pathway has led to strategical combination regimens to overcome this problem. In the past year, many encouraging results have been published or presented at conferences. Even though some of the data is still preliminary, these studies may bring practice-changing results and can lead to a clinical benefit for patients over the coming years. Because of these recent developments, the treatment of RAS-mutated mCRC has become a topic of great interest. Therefore, in this review, we will summarize the standard of care and discuss the most important emerging therapies for this patient population.

Belgian guidelines for pathology reporting of neuroendocrine neoplasms of the pancreaticobiliary and gastrointestinal tract

Since neuroendocrine neoplasms are rare tumors, registration of patient data in national and multinational registries is recommended. Indeed, this will facilitate multicenter studies on the epidemiology, efficacy and safety of diagnostic and therapeutic strategies for well-differentiated neuroendocrine tumors as well as for neuroendocrine carcinomas. In Belgium, data on patient and tumor characteristics of all newly diagnosed malignancies have been collected in the Belgian Cancer Registry since 2004 including anonymized full pathological reports. The Digestive Neuroendocrine Tumor (DNET) registry collects information on classification, staging, diagnostic tools and treatment in a prospective national online database. However, the terminology, classification and staging systems of neuroendocrine neoplasms have changed repeatedly over the past 20 years as a result of a better understanding of these rare tumors, by joining forces internationally. These frequent changes make it very difficult to exchange data or perform retrospective analyses. For optimal decision making, for a clear understanding and to allow reclassification according to the latest staging system, several items need to be described in the pathology report. This paper provides an overview of the essential items in reporting neuroendocrine neoplasms of the pancreaticobiliary and gastrointestinal tract.

The role of Immunotherapy in esophageal and gastric cancer

Upper gastrointestinal tract tumors historically have a poor prognosis. The decision to treat esophageal or gastric cancers by surgery, radiotherapy, systemic therapy, or a combination of these treatment modalities should always be discussed multidisciplinary. The introduction of immunotherapy has drastically transformed the treatment landscape of multiple solid malignancies. Emerging data from early and late phase clinical trials suggests that the use of immunotherapies that target immune checkpoint proteins such as PD-1/PD-L1 result in superior overall survival in advanced, metastatic, or recurrent esophageal and gastric cancer, whether or not with specific molecular characteristics such as PD-L1 expression level or microsatellite instability. This review offers an overview of the most recent advances in the field of immunotherapy treatment in esophageal and gastric cancer.

Humoral and Cellular Immune Responses against SARS-CoV-2 after Third Dose BNT162b2 following Double-Dose Vaccination with BNT162b2 versus ChAdOx1 in Patients with Cancer

PURPOSE

Patients with cancer display reduced humoral responses after double-dose COVID-19 vaccination, whereas their cellular response is more comparable with that in healthy individuals. Recent studies demonstrated that a third vaccination dose boosts these immune responses, both in healthy people and patients with cancer. Because of the availability of many different COVID-19 vaccines, many people have been boosted with a different vaccine from the one used for double-dose vaccination. Data on such alternative vaccination schedules are scarce. This prospective study compares a third dose of BNT162b2 after double-dose BNT162b2 (homologous) versus ChAdOx1 (heterologous) vaccination in patients with cancer.

EXPERIMENTAL DESIGN

A total of 442 subjects (315 patients and 127 healthy) received a third dose of BNT162b2 (230 homologous vs. 212 heterologous). Vaccine-induced adverse events (AE) were captured up to 7 days after vaccination. Humoral immunity was assessed by SARS-CoV-2 anti-S1 IgG antibody levels and SARS-CoV-2 50% neutralization titers (NT50) against Wuhan and BA.1 Omicron strains. Cellular immunity was examined by analyzing CD4+ and CD8+ T-cell responses against SARS-CoV-2-specific S1 and S2 peptides.

RESULTS

Local AEs were more common after heterologous boosting. SARS-CoV-2 anti-S1 IgG antibody levels did not differ significantly between homologous and heterologous boosted subjects [GMT 1,755.90 BAU/mL (95% CI, 1,276.95-2,414.48) vs. 1,495.82 BAU/mL (95% CI, 1,131.48-1,977.46)]. However, homologous-boosted subjects show significantly higher NT50 values against BA.1 Omicron. Subjects receiving heterologous boosting demonstrated increased spike-specific CD8+ T cells, including higher IFNγ and TNFα levels.

CONCLUSIONS

In patients with cancer who received double-dose ChAdOx1, a third heterologous dose of BNT162b2 was able to close the gap in antibody response.

Hemicolectomy versus appendectomy for patients with appendiceal neuroendocrine tumours 1-2 cm in size: a retrospective, Europe-wide, pooled cohort study

BACKGROUND

Awareness of the potential global overtreatment of patients with appendiceal neuroendocrine tumours (NETs) of 1-2 cm in size by performing oncological resections is increasing, but the rarity of this tumour has impeded clear recommendations to date. We aimed to assess the malignant potential of appendiceal NETs of 1-2 cm in size in patients with or without right-sided hemicolectomy.

METHODS

In this retrospective cohort study, we pooled data from 40 hospitals in 15 European countries for patients of any age and Eastern Cooperative Oncology Group performance status with a histopathologically confirmed appendiceal NET of 1-2 cm in size who had a complete resection of the primary tumour between Jan 1, 2000, and Dec 31, 2010. Patients either had an appendectomy only or an appendectomy with oncological right-sided hemicolectomy or ileocecal resection. Predefined primary outcomes were the frequency of distant metastases and tumour-related mortality. Secondary outcomes included the frequency of regional lymph node metastases, the association between regional lymph node metastases and histopathological risk factors, and overall survival with or without right-sided hemicolectomy. Cox proportional hazards regression was used to estimate the relative all-cause mortality hazard associated with right-sided hemicolectomy compared with appendectomy alone. This study is registered with ClinicalTrials.gov, NCT03852693.

FINDINGS

282 patients with suspected appendiceal tumours were identified, of whom 278 with an appendiceal NET of 1-2 cm in size were included. 163 (59%) had an appendectomy and 115 (41%) had a right-sided hemicolectomy, 110 (40%) were men, 168 (60%) were women, and mean age at initial surgery was 36·0 years (SD 18·2). Median follow-up was 13·0 years (IQR 11·0-15·6). After centralised histopathological review, appendiceal NETs were classified as a possible or probable primary tumour in two (1%) of 278 patients with distant peritoneal metastases and in two (1%) 278 patients with distant metastases in the liver. All metastases were diagnosed synchronously with no tumour-related deaths during follow-up. Regional lymph node metastases were found in 22 (20%) of 112 patients with right-sided hemicolectomy with available data. On the basis of histopathological risk factors, we estimated that 12·8% (95% CI 6·5 -21·1) of patients undergoing appendectomy probably had residual regional lymph node metastases. Overall survival was similar between patients with appendectomy and right-sided hemicolectomy (adjusted hazard ratio 0·88 [95% CI 0·36-2·17]; p=0·71).

INTERPRETATION

This study provides evidence that right-sided hemicolectomy is not indicated after complete resection of an appendiceal NET of 1-2 cm in size by appendectomy, that regional lymph node metastases of appendiceal NETs are clinically irrelevant, and that an additional postoperative exclusion of metastases and histopathological evaluation of risk factors is not supported by the presented results. These findings should inform consensus best practice guidelines for this patient cohort.

FUNDING

Swiss Cancer Research foundation.

Predictive model for BNT162b2 vaccine response in cancer patients based on blood cytokines and growth factors

Background

Patients with cancer, especially hematological cancer, are at increased risk for breakthrough COVID-19 infection. So far, a predictive biomarker that can assess compromised vaccine-induced anti-SARS-CoV-2 immunity in cancer patients has not been proposed.

Methods

We employed machine learning approaches to identify a biomarker signature based on blood cytokines, chemokines, and immune- and non-immune-related growth factors linked to vaccine immunogenicity in 199 cancer patients receiving the BNT162b2 vaccine.

Results

C-reactive protein (general marker of inflammation), interleukin (IL)-15 (a pro-inflammatory cytokine), IL-18 (interferon-gamma inducing factor), and placental growth factor (an angiogenic cytokine) correctly classified patients with a diminished vaccine response assessed at day 49 with >80% accuracy. Amongst these, CRP showed the highest predictive value for poor response to vaccine administration. Importantly, this unique signature of vaccine response was present at different studied timepoints both before and after vaccination and was not majorly affected by different anti-cancer treatments.

Conclusion

We propose a blood-based signature of cytokines and growth factors that can be employed in identifying cancer patients at persistent high risk of COVID-19 despite vaccination with BNT162b2. Our data also suggest that such a signature may reflect the inherent immunological constitution of some cancer patients who are refractive to immunotherapy.

18F-AlF-NOTA-octreotide outperforms 68Ga-DOTA-TATE/-NOC PET in neuroendocrine tumor patients: results from a prospective, multicenter study

Fluorine-18-labeled somatostatin analogs (SSAs) could represent a valid alternative to the current gold standard gallium-68-labeled SSAs for somatostatin receptor (SSTR) imaging in patients with neuroendocrine tumors (NETs), given their logistical advantages. Recently, ¹⁸F-AlF-NOTA-octreotide (¹⁸F-AlF-OC) has emerged as a promising candidate, but a thorough comparison with ⁶⁸Ga-DOTA-SSA in large patient groups is needed. This prospective, multicenter trial aims to demonstrate non-inferiority of ¹⁸F-AlF-OC compared with ⁶⁸Ga-DOTA-SSA PET in NET patients (ClinicalTrials.gov: NCT04552847). Methods: Seventy-five patients with histologically confirmed NET and a routine clinical ⁶⁸Ga-DOTATATE (n = 56) or ⁶⁸Ga-DOTANOC (n = 19) PET, performed within a 3-month interval of the study scan (median: 7 days; range: -30 to +32 days), were included. Patients underwent a whole-body PET, two hours after IV injection of 4 MBq/kg ¹⁸F-AlF-OC. A randomized, blinded consensus read was performed by two experienced readers to count tumor lesions. Following unblinding, the detection ratio (DR) was determined for each scan, i.e. the fraction of lesions detected on a scan compared to the union of lesions of both scans. The differential detection ratio (DDR; difference in DR between ¹⁸F-AlF-OC and ⁶⁸Ga-DOTATATE/NOC) per patient was calculated. Tracer uptake was evaluated by comparing SUV_max and tumor-to-background ratios (TBRs) in concordant lesions. Results: In total, 4709 different tumor lesions were detected, 3454 with ⁶⁸Ga-DOTATATE/NOC and 4278 with ¹⁸F-AlF-OC. The mean DR with ¹⁸F-AlF-OC was significantly higher than with ⁶⁸Ga-DOTATATE/NOC (91.1% vs. 75.3%; P<10-5). The resulting mean DDR was 15.8% with a lower margin of the 95% confidence interval (95% CI: 9.6%-22.0%) higher than -15%, the pre-specified boundary for non-inferiority. The mean DDR for the ⁶⁸Ga-DOTATATE and ⁶⁸Ga-DOTANOC subgroups were 11.8% (95% CI: 4.3-19.3) and 27.5% (95% CI: 17.8-37.1), respectively. The mean DDR for most organs was higher than zero, except for bone lesions (mean DDR -2.8% (95% CI: -17.8-12.2)). No significant differences in mean SUV_max were observed (P = 0.067), but mean TBR was significantly higher with ¹⁸F-AlF-OC than with ⁶⁸Ga-DOTATATE/NOC (31.7±36.5 vs. 25.1±32.7; P = 0.001). Conclusion: ¹⁸F-AlF-OC is non-inferior and even superior compared with ⁶⁸Ga-DOTATATE/NOC PET in NET patients. This validates ¹⁸F-AlF-OC as an option for clinical practice SSTR PET.

Prognostic implications of cellular senescence in resected non-small cell lung cancer

Background

Methods

Results

Conclusions

Longitudinal Copy-Number Alteration Analysis in Plasma Cell-Free DNA of Neuroendocrine Neoplasms is a Novel Specific Biomarker for Diagnosis, Prognosis, and Follow-up

PURPOSE

As noninvasive biomarkers are an important unmet need for neuroendocrine neoplasms (NEN), biomarker potential of genome-wide molecular profiling of plasma cell-free DNA (cfDNA) was prospectively studied in patients with NEN.

EXPERIMENTAL DESIGN

Longitudinal plasma samples were collected from patients with well-differentiated, metastatic gastroenteropancreatic and lung NEN. cfDNA was subjected to shallow whole-genome sequencing to detect genome-wide copy-number alterations (CNA) and estimate circulating tumor DNA (ctDNA) fraction, and correlated to clinicopathologic and survival data. To differentiate pancreatic NENs (PNEN) from pancreatic adenocarcinomas (PAAD) using liquid biopsies, a classification model was trained using tissue-based CNAs and validated in cfDNA.

RESULTS

One hundred and ninety-five cfDNA samples from 43 patients with NEN were compared with healthy control cfDNA (N = 100). Plasma samples from patients with PNEN (N = 21) were used for comparison with publicly available PNEN tissue (N = 98), PAAD tissue (N = 109), and PAAD cfDNA (N = 96). Thirty percent of the NEN cfDNA samples contained ctDNA and 44% of the patients had at least one ctDNA-positive (ctDNA⁺) sample. CNAs detected in cfDNA were highly specific for NENs and the classification model could distinguish PAAD and PNEN cfDNA samples with a sensitivity, specificity, and AUC of 62%, 86%, and 79%, respectively. ctDNA-positivity was associated with higher World Health Organization (WHO) grade, primary tumor location, and higher chromogranin A and neuron-specific enolase values. Overall survival was significantly worse for ctDNA⁺ patients and increased ctDNA fractions were associated with poorer progression-free survival.

CONCLUSIONS

Sequential genome-wide profiling of plasma cfDNA is a novel, noninvasive biomarker with high specificity for diagnosis, prognosis, and follow-up in metastatic NENs.

False positive Herpes Simplex IgM serology in COVID-19 patients correlates with SARS-CoV-2 IgM/IgG seropositivity

Differentiating COVID-19 from other causes of viral pneumonia, like herpes simplex (HSV), can be complicated by shared clinical and laboratory features. Viral pneumonia is mostly diagnosed based on molecular or serological techniques. Serological immunoassay interferences, often attributed to concurrent appearance of heterologous (viral) immunoglobulins, is well-known, but has not been studied in COVID-19 patients. Following false positive HSV immunoglobulin M (IgM) results in our index patient, 25 other COVID-19 patients were tested for HSV-1/2 IgM with the chemiluminescent Liaison assay and Euroimmun enzyme-linked immunosorbent assay. Forty-five percent of COVID-19 patients tested positive for HSV IgM with Liaison. No HSV indices were positive with Euroimmun enzyme-linked immunosorbent assay, suggesting immunoassay interference. Significant correlation between HSV IgM and SARS-CoV-2 IgM/IgG positivity was found. Adding 0.5% polyvinylpyrrolidone, inhibiting non-specific solid-phase adsorption, abolished interference in 22% of false positive cases, suggesting interference caused by solid-phase reactive IgM. Hence, serologic immunoassay results should be interpreted with caution in COVID-19 patients.

Quality of pathology reporting and adherence to guidelines in rectal neuroendocrine neoplasms: a Belgian national study

The incidence of neuroendocrine neoplasms (NEN) in the rectum is rising since the introduction of colonoscopy screening programs. Guidelines, such as the European NeuroEndocrine Tumor Society (ENETS) algorithm, are mainly based on expert opinion. The goal of this nationwide study is to gain a better insight into the evolution in pathology reporting and adherence to the ENETS guidelines in Belgium. In Belgium, all NENs have to be reported to the Belgian Cancer Registry. We thoroughly reviewed all available pathology reports, coded as rectal NEN between 2004 and 2015, and reclassified according to World Health Organisation (WHO) classification 2019. To evaluate the adherence to the ENETS guidelines, population-based cancer registry data were linked with the medical procedures of the Belgian Health Insurance database. A total of 670 rectal NEN were retained and 16% of the cases needed reclassification. Annual incidence between 2004 and 2015 tripled from 0,20 to 0,61 per 100.000 inhabitants. Reporting of Ki67 proliferation index ameliorated most, while reporting of tumor size, lymphovascular and perineural invasion remained disappointing. Endoscopic ultrasound was performed in only 36.6% of the cases, while the mostly recommended mode of treatment (endoscopic/surgical/no resection) was followed in the majority of the cases. Incidence of rectal NEN in Belgium increased throughout the years and quality of pathology reporting improved especially after the WHO classification update in 2010. The growing awareness and knowledge among clinicians and pathologists in the community counters the need for centralization.

Reduced humoral immune response after BNT162b2 coronavirus disease 2019 messenger RNA vaccination in cancer patients under antineoplastic treatment

Background

Cancer patients are at a higher risk of developing severe coronavirus disease 2019 (COVID-19). However, the safety and efficacy of COVID-19 vaccination in cancer patients undergoing treatment remain unclear.

Patients and methods

In this interventional prospective multicohort study, priming and booster doses of the BNT162b2 COVID-19 vaccine were administered 21 days apart to solid tumor patients receiving chemotherapy, immunotherapy, targeted or hormonal therapy, and patients with a hematologic malignancy receiving rituximab or after allogeneic hematopoietic stem cell transplantation. Vaccine safety and efficacy (until 3 months post-booster) were assessed. Anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) receptor-binding domain (RBD) antibody levels were followed over time (until 28 days after the booster) and in vitro SARS-CoV-2 50% neutralization titers (NT50) toward the wild-type Wuhan strain were analyzed 28 days after the booster.

Results

Local and systemic adverse events (AEs) were mostly mild to moderate (only 1%-3% of patients experienced severe AEs). Local, but not systemic, AEs occurred more frequently after the booster dose. Twenty-eight days after the booster vaccination of 197 cancer patients, RBD-binding antibody titers and NT50 were lower in the chemotherapy group {234.05 IU/ml [95% confidence interval (CI) 122.10-448.66] and 24.54 (95% CI 14.50-41.52), respectively} compared with healthy individuals [1844.93 IU/ml (95% CI 1383.57-2460.14) and 122.63 (95% CI 76.85-195.67), respectively], irrespective of timing of vaccination during chemotherapy cycles. Extremely low antibody responses were seen in hematology patients receiving rituximab; only two patients had RBD-binding antibody titers necessary for 50% protection against symptomatic SARS-CoV-2 infection (<200 IU/ml) and only one had NT50 above the limit of detection. During the study period, five cancer patients tested positive for SARS-CoV-2 infection, including a case of severe COVID-19 in a patient receiving rituximab, resulting in a 2-week hospital admission.

Conclusion

The BNT162b2 vaccine is well-tolerated in cancer patients under active treatment. However, the antibody response of immunized cancer patients was delayed and diminished, mainly in patients receiving chemotherapy or rituximab, resulting in breakthrough infections.

•

The BNT162b2 vaccine is well-tolerated in cancer patients, including patients under immunotherapy.

•

Full BNT162b2 vaccination results in a blunted humoral immune response in cancer patients under active treatment.

•

The humoral immune response after BNT162b2 vaccination varies between different antineoplastic treatments.

•

Two doses of BNT162b2 vaccination may insufficiently protect patients receiving chemotherapy or rituximab against SARS-CoV-2.

Cancer-Associated Fibroblasts as a Common Orchestrator of Therapy Resistance in Lung and Pancreatic Cancer

Cancer arises from mutations accruing within cancer cells, but the tumor microenvironment (TME) is believed to be a major, often neglected, factor involved in therapy resistance and disease progression. Cancer-associated fibroblasts (CAFs) are prominent and key components of the TME in most types of solid tumors. Extensive research over the past decade revealed their ability to modulate cancer metastasis, angiogenesis, tumor mechanics, immunosuppression, and drug access through synthesis and remodeling of the extracellular matrix and production of growth factors. Thus, they are considered to impede the response to current clinical cancer therapies. Therefore, targeting CAFs to counteract these protumorigenic effects, and overcome the resistance to current therapeutic options, is an appealing and emerging strategy. In this review, we discuss how CAFs affect prognosis and response to clinical therapy and provide an overview of novel therapies involving CAF-targeting agents in lung and pancreatic cancer.

Copy number alterations in plasma cell-free DNA from metastatic gastroenteropancreatic neuroendocrine neoplasms

372

Background: Recent studies, including our proof-of-concept study, demonstrated the possibility to detect tumor-derived molecular alterations in cell-free DNA (cfDNA) from plasma of patients with a gastroenteropancreatic neuroendocrine neoplasm (GEP-NEN). More in-depth evaluation of the biomarker potential of cfDNA in GEP-NENs is warranted, since highly sensitive and specific blood-based biomarkers are an important unmet need for this tumor type. The aim of our study was to detect tumor-associated copy number alterations (CNAs) in cfDNA from GEP-NEN patients to molecularly characterize the tumor and to estimate tumor fraction, as a measure of tumor burden, and to evaluate changes in these parameters over time. Methods: Metastatic GEP-NEN patients were included within NETwerk, a multi-institutional network of nine hospitals in Belgium. Clinicopathological data were collected to correlate experimental and clinical findings. Plasma samples were collected from all patients and cfDNA was extracted and subjected to shallow whole-genome sequencing (WGS). Detection of CNAs and estimation of tumor fraction, based on the sequencing data, were performed using the R-based tool ichorCNA. Results: In total, 80 samples of 29 metastatic GEP-NEN patients were analyzed using shallow WGS. All patients had a well-differentiated GEP-NEN of Grade 1/2 and primary sites were pancreas (N = 15), small intestine (N = 9), colon (N = 1), caecum (N = 1), ileocaecal valve (N = 1), pylorus (N = 1) and unknown (N = 1). Median number of samples per patient was two, with a median time between first and last sampling of six months. In 25 cfDNA samples from nine patients (31%), CNAs with tumor fractions higher than 3% could be detected. The primary tumor site of all CNA-positive patients was pancreas, corresponding to 60% of included pancreatic NEN (PNEN) patients. Six of the CNA-positive patients were included at initiation of everolimus treatment. The detected CNA patterns were similar to the copy number profiles of PNENs described in literature, e.g. whole-chromosome gains of chromosomes 5, 7, 9, 12, 13, 14, 19 and 20. CNA profiles were relatively stable over time, although in two patients new alterations did arise. Tumor fractions changed over time, which could be linked to changes in tumor burden, tumor progression and treatment response according to RECIST1.1 criteria and will be further examined, including in additional samples that are being collected. Conclusions: Cell-free DNA of metastatic GEP-NEN patients contains CNAs that correspond to CNA profiles seen in tumor tissue samples. CNAs can be used to quantify the tumor fraction in cfDNA over time, which will be linked to tumor progression in our ongoing study, particularly in the promising subgroup of PNEN patients.

Current practice in approaching controversial diagnostic and therapeutic topics in gastroenteropancreatic neuroendocrine neoplasm management. Belgian multidisciplinary expert discussion based on a modified Delphi method

BACKGROUND AND STUDY AIMS

Neuroendocrine neoplasms (NENs) are relatively rare, with marked clinical and biological heterogeneity. Consequently, many controversial areas remain in diagnosis and optimal treatment stratification for NEN patients. We wanted to describe current clinical practice regarding controversial NEN topics and stimulate critical thinking and mutual learning among a Belgian multidisciplinary expert panel.

PATIENTS AND METHODS

A 3-round, Delphi method based project, coordinated by a steering committee (SC), was applied to a predefined multidisciplinary NEN expert panel studying the following controversial topics : factors guiding therapeutic decision making, the use of somatostatin analogues (SSA) in adjuvant setting, the interference between non-radioactive and radioactive SSAs, challenging small intestine neuroendocrine tumor (NET) cases, the approach of the carcinoid syndrome, the role of chemotherapy in well differentiated NET, the relevance of NET G3 and neuroendocrine carcinoma subclassification and the role of imaging techniques in NEN management.

RESULTS

A high level of consensus exists regarding the necessary diagnostic work-up, use of imaging techniques and interference between non-radioactive and radioactive SSAs. However, the prognostic impact of tumor functionality might be overrated and adequate diarrhea differential diagnostic work-up in these patients is underused. Significant differences are seen between individual experts and centers regarding treatment preferences both on the treatment modality level, as well as the choice of specific drugs (e.g. chemotherapy regimen).

CONCLUSIONS

A Delphi-like multi-round expert discussion proves useful to boost critical thinking and discussion among experts of different background, as well as to describe current clinical practice and stimulate mutual learning in the absence of high-level scientific guidance.

PDX1 DNA Methylation Distinguishes Two Subtypes of Pancreatic Neuroendocrine Neoplasms with a Different Prognosis

DNA methylation is a crucial epigenetic mechanism for gene expression regulation and cell differentiation. Furthermore, it was found to play a major role in multiple pathological processes, including cancer. In pancreatic neuroendocrine neoplasms (PNENs), epigenetic deregulation is also considered to be of significance, as the most frequently mutated genes have an important function in epigenetic regulation. However, the exact changes in DNA methylation between PNENs and the endocrine cells of the pancreas, their likely cell-of-origin, remain largely unknown. Recently, two subtypes of PNENs have been described which were linked to cell-of-origin and have a different prognosis. A difference in the expression of the transcription factor PDX1 was one of the key molecular differences. In this study, we performed an exploratory genome-wide DNA methylation analysis using Infinium Methylation EPIC arrays (Illumina) on 26 PNENs and pancreatic islets of five healthy donors. In addition, the methylation profile of the PDX1 region was used to perform subtyping in a global cohort of 83 PNEN, 2 healthy alpha cell and 3 healthy beta cell samples. In our exploratory analysis, we identified 26,759 differentially methylated CpGs and 79 differentially methylated regions. The gene set enrichment analysis highlighted several interesting pathways targeted by altered DNA methylation, including MAPK, platelet-related and immune system-related pathways. Using the PDX1 methylation in 83 PNEN, 2 healthy alpha cell and 3 healthy beta cell samples, two subtypes were identified, subtypes A and B, which were similar to alpha and beta cells, respectively. These subtypes had different clinicopathological characteristics, a different pattern of chromosomal alterations and a different prognosis, with subtype A having a significantly worse prognosis compared with subtype B (HR 0.22 [95% CI: 0.051–0.95], p = 0.043). Hence, this study demonstrates that several cancer-related pathways are differently methylated between PNENs and normal islet cells. In addition, we validated the use of the PDX1 methylation status for the subtyping of PNENs and its prognostic importance.

Clinical applications of (epi)genetics in gastroenteropancreatic neuroendocrine neoplasms: Moving towards liquid biopsies

High-throughput analysis, including next-generation sequencing and microarrays, have strongly improved our understanding of cancer biology. However, genomic data on rare cancer types, such as neuroendocrine neoplasms, has been lagging behind. Neuroendocrine neoplasms (NENs) develop from endocrine cells spread throughout the body and are highly heterogeneous in biological behavior. In this challenging disease, there is an urgent need for new therapies and new diagnostic, prognostic, follow-up and predictive biomarkers to aid patient management. The last decade, molecular data on neuroendocrine neoplasms of the gastrointestinal tract and pancreas, termed gastroenteropancreatic NENs (GEP-NENs), has strongly expanded. The aim of this review is to give an overview of the recent advances on (epi)genetic level and highlight their clinical applications to address the current needs in GEP-NENs. We illustrate how molecular alterations can be and are being used as therapeutic targets, how mutations in DAXX/ATRX and copy number variations could be used as prognostic biomarkers, how far we are in identifying predictive biomarkers and how genetics can contribute to GEP-NEN classification. Finally, we discuss recent studies on liquid biopsies in the field of GEP-NENs and illustrate how liquid biopsies can play a role in patient management. In conclusion, molecular studies have suggested multiple potential biomarkers, but further validation is ongoing.

Resistance to targeted treatment of gastroenteropancreatic neuroendocrine tumors

The mammalian target of rapamycin (mTOR) is part of the phosphoinositide-3-kinase (PI3K)/protein kinase B (Akt)/mTOR signaling. The PI3K/Akt/mTOR pathway has a pivotal role in the oncogenesis of neuroendocrine tumors (NETs). In addition, vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF) drive angiogenesis in NETs and therefore contributes to neuroendocrine tumor development. Hence, mTOR and angiogenesis inhibitors have been developed. Everolimus, a first-generation mTOR inhibitor, has shown significant survival benefit in advanced gastroenteropancreatic NETs. Sunitinib, a pan-tyrosine kinase inhibitor that targets the VEGF receptor, has proven to increase progression-free survival in advanced pancreatic NETs. Nevertheless, primary and acquired resistance to rapalogs and sunitinib has limited the clinical benefit for NET patients. Despite the identification of multiple molecular mechanisms of resistance, no predictive biomarker has made it to the clinic. This review is focused on the mTOR signaling and angiogenesis in NET, the molecular mechanisms of primary and acquired resistance to everolimus and sunitinib and how to overcome this resistance by alternative drug compounds.

Hotspot DAXX, PTCH2 and CYFIP2 mutations in pancreatic neuroendocrine neoplasms

Mutations in DAXX/ATRX, MEN1 and genes involved in the phosphoinositide-3-kinase/Akt/mammalian target of rapamycin (PI3K/Akt/mTOR) pathway have been implicated in pancreatic neuroendocrine neoplasms (pNENs). However, mainly mutations present in the majority of tumor cells have been identified, while proliferation-driving mutations could be present only in small fractions of the tumor. This study aims to identify high- and low-abundance mutations in pNENs using ultra-deep targeted resequencing. Formalin-fixed paraffin-embedded matched tumor-normal tissue of 38 well-differentiated pNENs was sequenced using a HaloPlex targeted resequencing panel. Novel amplicon-based algorithms were used to identify both single nucleotide variants (SNVs) and insertion-deletions (indels) present in >10% of reads (high abundance) and in <10% of reads (low abundance). Found variants were validated by Sanger sequencing. Sequencing resulted in 416,711,794 reads with an average target base coverage of 2663 ± 1476. Across all samples, 32 high-abundance somatic, 3 germline and 30 low-abundance mutations were withheld after filtering and validation. Overall, 92% of high-abundance and 84% of low-abundance mutations were predicted to be protein damaging. Frequently, mutated genes were MEN1, DAXX, ATRX, TSC2, PI3K/Akt/mTOR and MAPK-ERK pathway-related genes. Additionally, recurrent alterations on the same genomic position, so-called hotspot mutations, were found in DAXX, PTCH2 and CYFIP2. This first ultra-deep sequencing study highlighted genetic intra-tumor heterogeneity in pNEN, by the presence of low-abundance mutations. The importance of the ATRX/DAXX pathway was confirmed by the first-ever pNEN-specific protein-damaging hotspot mutation in DAXX. In this study, both novel genes, including the pro-apoptotic CYFIP2 gene and hedgehog signaling PTCH2, and novel pathways, such as the MAPK-ERK pathway, were implicated in pNEN.

Cell-Free DNA From Metastatic Pancreatic Neuroendocrine Tumor Patients Contains Tumor-Specific Mutations and Copy Number Variations

Background: Detection of tumor-specific alterations in cell-free DNA (cfDNA) has proven valuable as a liquid biopsy for several types of cancer. So far, use of cfDNA remains unexplored for pancreatic neuroendocrine tumor (PNET) patients. Methods: From 10 PNET patients, fresh frozen tumor tissue, buffy coat and plasma samples were collected. Whole-exome sequencing of primary tumor and germline DNA was performed to identify tumor-specific variants and copy number variations (CNVs). Subsequently, tumor-specific variants were quantified in plasma cfDNA with droplet digital PCR. In addition, CNV analysis of cfDNA was performed using shallow whole-genome sequencing. Results: Tumor-specific variants were detected in perioperative plasma samples of two PNET patients, at variant allele fractions (VAFs) of respectively 19 and 21%. Both patients had metastatic disease at time of surgery, while the other patients presented with localized disease. In the metastatic patients, CNV profiles of tumor tissue and cfDNA were significantly correlated. A follow-up plasma sample of a metastatic patient demonstrated an increased VAF (57%) and an increased chromosomal instability, in parallel with an increase in tumor burden. Conclusions: We are the first to report the presence of tumor-specific genetic alterations in cfDNA of metastatic PNET patients and their evolution during disease progression. Additionally, CNV analysis in cfDNA shows potential as a liquid biopsy.

Long-term acquired everolimus resistance in pancreatic neuroendocrine tumours can be overcome with novel PI3K-AKT-mTOR inhibitors

Background:

The mTOR-inhibitor everolimus improves progression-free survival in advanced pancreatic neuroendocrine tumours (PNETs). However, adaptive resistance to mTOR inhibition is described.

Methods:

QGP-1 and BON-1, two human PNET cell lines, were cultured with increasing concentrations of everolimus up to 22 weeks to reach a dose of 1 μM everolimus, respectively, 1000-fold and 250-fold initial IC₅₀. Using total DNA content as a measure of cell number, growth inhibitory dose–response curves of everolimus were determined at the end of resistance induction and over time after everolimus withdrawal. Response to ATP-competitive mTOR inhibitors OSI-027 and AZD2014, and PI3K-mTOR inhibitor NVP-BEZ235 was studied. Gene expression of 10 PI3K-Akt-mTOR pathway-related genes was evaluated using quantitative real-time PCR (RT–qPCR).

Results:

Long-term everolimus-treated BON-1/R and QGP-1/R showed a significant reduction in everolimus sensitivity. During a drug holiday, gradual return of everolimus sensitivity in BON-1/R and QGP-1/R led to complete reversal of resistance after 10–12 weeks. Treatment with AZD2014, OSI-027 and NVP-BEZ235 had an inhibitory effect on cell proliferation in both sensitive and resistant cell lines. Gene expression in BON-1/R revealed downregulation of MTOR, RICTOR, RAPTOR, AKT and HIF1A, whereas 4EBP1 was upregulated. In QGP-1/R, a downregulation of HIF1A and an upregulation of ERK2 were observed.

Conclusions:

Long-term everolimus resistance was induced in two human PNET cell lines. Novel PI3K-AKT-mTOR pathway-targeting drugs can overcome everolimus resistance. Differential gene expression profiles suggest different mechanisms of everolimus resistance in BON-1 and QGP-1.

Whole-exome characterization of pancreatic neuroendocrine tumor cell lines BON-1 and QGP-1

The human BON-1 and QGP-1 cell lines are two frequently used models in pancreatic neuroendocrine tumor (PNET) research. Data on the whole-exome genetic constitution of these cell lines is largely lacking. This study presents, to our knowledge, the first whole-exome profile of the BON-1 and QGP-1 cell lines. Cell line identity was confirmed by short tandem repeat profiling. Using GTG-banding and a CytoSNP-12v2 Beadchip array, cell line ploidy and chromosomal alterations were determined in BON-1 and QGP-1. The exomes of both cell lines were sequenced on Ilumina's HiSeq next-generation sequencing (NGS) platform. Single-nucleotide variants (SNVs) and insertions and deletions (indels) were detected using the Genome Analysis ToolKit. SNVs were validated by Sanger sequencing. Ploidy of BON-1 and QGP-1 was 3 and 4 respectively, with long stretches of loss of heterozygosity across multiple chromosomes, which is associated with aggressive tumor behavior. In BON-1, 57 frameshift indels and 1725 possible protein-altering SNVs were identified in the NGS data. In the QGP-1 cell line, 56 frameshift indels and 1095 SNVs were identified. ATRX, a PNET-associated gene, was mutated in both cell lines, while mutation of TSC2 was detected in BON-1. A mutation in NRAS was detected in BON-1, while KRAS was mutated in QGP-1, implicating aberrations in the RAS pathway in both cell lines. Homozygous mutations in TP53 with possible loss of function were identified in both cell lines. Various MUC genes, implicated in cell signaling, lubrication and chemical barriers, which are frequently expressed in PNET tissue samples, showed homozygous protein-altering SNVs in the BON-1 and QGP-1 cell lines.

The effect of pectin on swelling and permeability characteristics of free films containing Eudragit RL and/or RS as a coating formulation aimed for colonic drug delivery

BACKGROUND AND THE PURPOSE OF THE STUDY

The potential of pectin as a bacterially degradable polysaccharide for colon drug delivery has been demonstrated. Due to the high solubility and swelling properties of pectin in aqueous media, it is frequently used in combination with water insoluble polymers for targeting drugs to the colon. The aim of this study was to evaluate free films containing pectin as a bacterially-degradable polysaccharide in combination with Eudragit RL (ERL) and/or RS (ERS) as a coating formulation for colonic drug delivery.

METHODS

Isolated free films comprising 20% pectin and 80% ERL or ERS and their combination in 1:1 ratio were prepared by casting method. Then, free films were evaluated by water vapor transmission (WVT), swelling and permeability experiments for theophylline and indomethacin in different media.

RESULTS

Formulations containing ERL exhibited higher WVT, swelling and permeability compared with formulations containing ERS. The permeability of theophylline through free films composed of pectin and eudragit polymers in simulated colonic media was not significantly different from those obtained in other media. However indomethacin free films containing pectin and ERL showed higher permeation in simulated colonic fluid (SCF) compared to the other media.

MAJOR CONCLUSION

Formulation containing pectin and ERL may be suitable as a coating formulation for colon targeted delivery of drugs of low solubility such as indomethacin.