Introduction

Therapeutic drug monitoring (TDM) of intravenous (IV) infliximab is increasingly practiced to improve therapeutic outcomes of patients with inflammatory bowel diseases (IBD). Recently, a subcutaneous (SC) formulation of infliximab was approved for maintenance treatment of IBD [1].
In the present work, we introduce a software tool to guide infliximab dosing by predicting infliximab concentrations after switching to the SC formulation.

Aims & Methods

The infliximab population pharmacokinetics (popPK) model was previously developed using data from pivotal trials [2]. The popPK model code was reconstructed using R (v4.3.0). A software tool was developed using the Shiny package (v1.7.4). Bayesian forecasting was implemented using mapbayr (v0.10.0), which was used to estimate individual PK parameters through maximum a posteriori estimation.

External validation data were obtained from the prospective, multicenter REMSWITCH trial [3]. For each patient, a pre-switch infliximab trough concentration (TC) was used to predict a post-switch TC. Predicted and observed post-switch TCs were compared, and absolute and relative prediction errors (PE) were calculated. Prediction errors were compared between patients with and without relapse. Relapse was defined as an increase in fecal calprotectin ≥150 mg/g from baseline.

A simulation study was performed to demonstrate how the software tool can guide the IV-to-SC switch. Simulation conditions were:
- Dosing: 10 mg/kg IV every four weeks (q4w) to 240 mg SC every two weeks (q2w)
- Patient: 70 kg, no antibodies towards infliximab (ATI), no co-administration of methotrexate
- Pre-switch TC: 17.6 mg/L

Results

A total of 77 patients contributed one pre/post-switch TC pair each. Three patients had detectable ATI in the pre-switch sample. Three other patients were cotreated with methotrexate.
Predicted infliximab TCs were unbiased in the absence of relapse (Table 1). However, the model tended to overpredict infliximab TC in patients who experienced a relapse.

_{Table 1. Predictive performance of the model.}

	No relapse (N=60)		Relapse (N=17)
	Median	[IQR]	Median	[IQR]
aPE (mg/L)	-0.06	[-2.4–3.3]	+3.8	[-1.0–5.7]
rPE (%)	-0.6	[-20.1–30.2]	+34.3	[-10.0–67.1]

^{Abbreviations: aPE, absolute prediction error (calculated as; predicted - observed); IQR, interquartile range; N, number of patients; rPE, relative prediction error (calculated as; [predicted - observed] / observed * 100%).}

In the IV-to-SC simulation case, individual PK parameters (clearance 0.44 L/day, central volume of distribution 2.9 L, peripheral volume of distribution 27.0 L, and intercompartmental clearance 13.0 L/day) resulted in a post-switch TC of 18.6 mg/L right before the third SC injection. The simulation thus predicted no drop in TC after switching, thus presenting a likely safe switch strategy (considering the general belief that TCs drive efficacy).

Conclusion

The clinically validated, in-house developed software tool (https://lpmx.shinyapps.io/infliximab/) allows interactive simulations and personalized predictions to guide infliximab dosing while switching formulations. Predictions for patients without relapse were unbiased yet precision is likely compromised by variable SC bioavailability or possibly by time-varying PK. Overprediction of TC is likely driven by increased disease activity, characterized by an increased infliximab clearance and thus lower-than-expected infliximab observations, serving as a clinical alarm signal and warranting closer monitoring [4,5].

References

[1] S. Schreiber et al., “Randomized Controlled Trial: Subcutaneous vs Intravenous Infliximab CT-P13 Maintenance in Inflammatory Bowel Disease,” Gastroenterology, vol. 160, no. 7, pp. 2340–2353, Jun. 2021, doi: 10.1053/j.gastro.2021.02.068.
[2] “Remsima European Public Assessment Report.pdf.”
[3] A. Buisson et al., “Effectiveness of switching from intravenous to subcutaneous infliximab in patients with inflammatory bowel diseases: the REMSWITCH study,” Clin Gastroenterol Hepatol, vol. 21, no. 9, pp. 2338-2346.e3, 2023, doi: 10.1016/j.cgh.2022.08.011.
[4] W. Kantasiripitak, Z. Wang, I. Spriet, M. Ferrante, and E. Dreesen, “Recent advances in clearance monitoring of monoclonal antibodies in patients with inflammatory bowel diseases,” Expert Review of Clinical Pharmacology, vol. 14, no. 12, pp. 1455–1466, Dec. 2021, doi: 10.1080/17512433.2021.2028619.
[5] J. F. Brandse et al., “Loss of Infliximab Into Feces Is Associated With Lack of Response to Therapy in Patients With Severe Ulcerative Colitis,” Gastroenterology, vol. 149, no. 2, pp. 350-355.e2, Aug. 2015, doi: 10.1053/j.gastro.2015.04.016.

Disclosure

YH and ZW are supported by a research grant by Research Foundation Flanders–FWO (1SHAA24N, 1SF2922N). MF has received consulting/lecture fees from AbbVie, Amgen, Arena, Biogen, Celltrion Healthcare, CTMA, Galapagos, Janssen, MSD, Pfizer, Takeda, Tillotts. MSD, Gilead, Celgene, Sandoz, and Ferring. MN has received board membership, consultancy, or lecture fees from AbbVie, Adacyte, Amgen, Arena, Biogen, CTMA, Celltrion Healthcare, Ferring, Fresenius-Kabi, Janssen, Mayoli-Spindler, MSD, Pfizer, and Takeda. AB has received consulting fees from AbbVie, Amgen, Arena, Biogen, Celltrion Healthcare, CTMA, Galapagos, Janssen, MSD, Nexbiome, Pfizer, Roche, Takeda, and Tillotts; and lecture fees from AbbVie, Amgen, Biogen, Galapagos, Janssen, Mayoli-Spindler, MSD, Norgine, Pfizer, Roche, Takeda, Tillotts, and Vifor Pharma. ED has received consultancy fees from Alimentiv and argenx, lecture fees from Galapagos and Celltrion, and financial support from Janssen, Prometheus, and Sandoz. The remaining authors disclose no conflicts.

Introduction

Colorectal cancer (CRC) is the third most diagnosed cancer worldwide¹, with a similar prevalence observed in Denmark, where it ranks as the third most frequent malignancy². In recent decades, the incidence of early-onset colorectal cancer—defined as CRC diagnosed in individuals under 50 years of age—has been rising^3,4. Since CRC is often asymptomatic in the early stages, late-stage diagnosis is associated with high mortality rates⁵. Therefore, it is crucial to develop new strategies to identify risk factors and early tumour formation, enabling timely prevention, treatment, and improved patient outcomes⁶. While colonoscopy remains the gold standard, it is invasive and often unnecessary; data from Region Zealand show that nearly 60% of individuals undergoing colonoscopy after a positive faecal immunochemical test (FIT) do not have lesions requiring treatment⁷. The development of molecular diagnostics, such as faecal DNA-based screening, offers a promising alternative that could significantly improve early detection while reducing the number of unnecessary colonoscopies, particularly in high-risk populations such as those with inflammatory bowel disease (IBD), previous CRC history, or genetic predispositions.

Aims & Methods

We evaluated two alternative approaches for detecting colorectal cancer-related mutations from faecal-derived human DNA: short-read next-generation sequencing (NGS) and digital PCR (dPCR). The aim was to assess whether these methods could support a non-invasive screening strategy that does not rely on the detection of occult blood. Faecal samples were collected from patients in Region Zealand who tested positive in the Danish national colorectal cancer (CRC) screening programme between January 2022 and January 2023 (FIT ≥100 ng/mL).
Faecal DNA was extracted using the QIAamp Fast DNA Stool Mini Kit (Qiagen) with RNase treatment. Formalin-fixed paraffin-embedded (FFPE) tumour samples were processed with the GeneRead DNA FFPE Kit (Qiagen). For next-generation sequencing (NGS), libraries were prepared with the QIAseq Targeted DNA Pro kit (Qiagen), targeting regions commonly mutated in CRC. Digital PCR (dPCR) was performed using the QIAcuity Probe PCR Kit and a panel targeting six validated single-nucleotide variants (SNVs) in CRC driver genes.

Results

Of the 71 sequencing DNA libraries generated from faecal samples, only three yielded more than 100 high-quality human reads, highlighting the challenge of recovering host DNA from stool material due to high gut microbiome content and inhibitory substances. Across the 33 patients successfully analysed, a total of 163 faecal DNA variants were detected by either NGS or dPCR. Of these, 21 were classified as oncogenic or likely oncogenic in colorectal cancer, and five were pathogenic variants not directly linked to CRC. These combined results demonstrate the feasibility of faecal DNA-based mutation detection as a non-invasive screening tool and underscore the importance of adequate DNA recovery for reliable variant identification.

Conclusion

Our study provides compelling evidence that mutation-based faecal DNA screening is feasible and may augment current CRC detection strategies. While current sensitivity remains suboptimal, the high PPV of dPCR under stringent quality control is encouraging. Our findings contribute to a growing body of literature supporting the transition toward precision diagnostics in cancer screening. When implemented within a personalised framework, faecal DNA mutation analysis may reduce unnecessary colonoscopies and enable early detection of high-risk lesions.

References

1. Sung, H., et al. (2021). Global Cancer Statistics 2020: GLOBOCAN estimates of incidence and mortality worldwide for 36 cancers in 185 countries. CA: A Cancer Journal for Clinicians 71(3), 209–249. DOI: 10.3322/caac.21660.
2. Njor, S. H., et al. (2018). Three years of colorectal cancer screening in Denmark. Cancer Epidemiology 57, 39–44. DOI: 10.1016/j.canep.2018.09.003.
3. Vuik, F. E., et al. (2019). Increasing incidence of colorectal cancer in young adults in Europe over the last 25 years. Gut 68(10), 1820–1826. DOI: 10.1136/gutjnl-2018-317592.
4. Akimoto, N., et al. (2021). Rising incidence of early-onset colorectal cancer – a call to action. Nature Reviews Clinical Oncology 18(4), 230–243. DOI: 10.1038/s41571-020-00445-1.
5. Ilyas, M. I. M. (2023). Epidemiology of Stage IV Colorectal Cancer: Trends in the Incidence, Prevalence, Age Distribution, and Impact on Life Span. Clinics in Colon and Rectal Surgery 37(2), 57–61. DOI: 10.1055/s-0043-1761447.
6. Wolf, A. M. D., et al. (2018). Colorectal cancer screening for average-risk adults: 2018 guideline update from the American Cancer Society. CA: A Cancer Journal for Clinicians 68(4), 250–281. DOI: 10.3322/caac.21457.
7. Nielson, C. M., et al. (2018). Positive predictive values of fecal immunochemical tests used in the STOP CRC pragmatic trial. Cancer Medicine 7(9), 4781–4790. DOI: 10.1002/cam4.1727.

Disclosure

The authors declare no competing interests.

Introduction

Massive gastrointestinal bleeding is a clinical condition that is poorly studied due to its abrupt presentation, involvement of various clinical services, and the high and rapid mortality of patients. We present the preliminary results of a multicenter registry that includes 21 hospitals from Spain and Hispanic America, analyzing factors related to mortality and need for intervention.

Aims & Methods

Since January 2023, 403 patients over 18 years old who presented to the emergency departments of participating hospitals with massive gastrointestinal bleeding, defined as bleeding accompanied by signs of shock and requiring transfusion of at least 2 units of blood within the first 24 hours of admission, were included. Demographic variables, comorbidities, treatments including NSAIDs, antiplatelets, and anticoagulants, clinical presentation variables, medical, endoscopic, and surgical variables, and a 6-month follow-up were collected.
The aim of this study was to analyze factors related to mortality and the need for intervention in patients with massive gastrointestinal bleeding.

Results

A total of 403 patients with a mean age of 64.5 ± 15.7 years were included (male 68.7%). Main comorbidities were cirrhosis (31%), diabetes (28%) and a previous UGIB (25%). 8.4% of patients had already been admitted to the hospital, and 29% were on antithrombotic (16.6% antiplatelets and 16.4% anticoagulants). On admission we observed SPB: 91±22 mmHg, heart rate 101 ± 21; and an altered mental status in 31%. Mean hemoglobin levels 7.6±2.5 g/dl, urea: 98±67, albumin 2.16±1.3, INR: 3.9±7. The most common causes were esophageal varices (29%), gastric ulcer (25%) and duodenal ulcer (25%). Endoscopic intervention was needed in 60%, with mortality rate of15.4%. Mean admission was 8.6±10 days, and patients needed 4±3 red blood cells units. When analyzing in-hospital mortality, we observed that the age of patients who died was higher than that of survivors (68.2±15 vs. 63.6±16; p=0.033), with the former requiring more packed red blood cells (5±5.5 vs. 3.5±2; p=0.043). Patients who died had a lower frequency of gastric ulcer (14% vs. 27%; p=0.034), a higher frequency of altered mental status (42.6% vs. 29%; p=0.036), and a lower rate of endoscopic therapy applied (43.3% vs. 63.6%; p<0.0001). In logistic regression, gastric ulcer etiology and endoscopic therapy were protective factors against mortality (Table 2).
Regarding the need for intervention, more patients with liver cirrhosis required it (73% vs. 60%, p=0.018), patients with hematemesis (73% vs. 52%; p<0.0001), patients without melena (60% vs. 76%; p=0.002), with syncope (76.3% vs. 61%; p=0.06), etiologies other than gastric ulcer (78% vs. 56%; p=0.028), and the presence of esophageal varices (83% vs. 57%; p<0.0001). In binary logistic regression, liver cirrhosis, hematemesis, and syncope were risk factors for the need for intervention.

Conclusion

Age, altered mental status, and lower frequency of endoscopic therapy are risk factors for mortality due to massive gastrointestinal bleeding. Gastric ulcer as an etiology and receiving endoscopic therapy acted as protective factors against mortality. Indeed, in both situations, it might be related to an opportunity window to receive appropriate treatment, especially when compared with more cataclysmic types of bleeding, such as variceal or posterior duodenal bulb wall, which sometimes can be challenging and utterly abrupt. Regarding the need for intervention, liver cirrhosis, hematemesis, and syncope were independent risk factors for the need for endoscopy, surgery, or interventional radiology.

Introduction

Eosinophilic esophagitis (EoE) is a chronic, progressive, type 2 inflammatory disease of the esophagus characterized by multiple histopathologic abnormalities. In children and adults, EoE is diagnosed with a peak eosinophil count (PEC) ≥15 eosinophils/high-power field (eos/hpf) in endoscopically-obtained esophageal biopsies, yet PEC may not be a reliable marker of disease severity or treatment response. The EoE Histologic Scoring System (EoEHSS) provides an objective method for evaluating a range of histologic changes associated with EoE, beyond eosinophilia. Dupilumab, a fully human monoclonal antibody that blocks interleukin (IL)-4 and IL-13, key drivers of type 2 inflammation, is approved in the US and EU for the treatment of EoE in patients aged ≥1 year, weighing ≥15 kg.

Aims & Methods

This post hoc analysis assesses the impact of dupilumab vs placebo on histopathologic endpoints, PEC and EoEHSS grade/stage scores, in children, adolescents, and adults from a pooled analysis of the EoE KIDS (NCT04394351) and LIBERTY EoE TREET (NCT03633617) studies. Patients from Part A of EoE KIDS randomized to weight-tiered, higher-exposure (HE) dupilumab or placebo for 16 weeks, and patients from Parts A/B of LIBERTY EoE TREET randomized to weekly dupilumab 300 mg or placebo for 24 weeks, were included. Patients continued dupilumab or switched from placebo to dupilumab to Week (W) 52. Biopsies were collected from proximal, mid, and distal esophagus. PEC and EoEHSS grade/stage scores were assessed at W16/24 and W52. All P-values are nominal.

Results

The pooled cohort included 159 patients who received dupilumab and 152 who received placebo. Baseline characteristics were generally comparable between the dupilumab and placebo groups (mean [standard deviation] EoE-HSS grade score: 1.3 [0.4] and 1.3 [0.4], EoEHSS stage score: 1.3 [0.3] and 1.3 [0.4], respectively). At W16/24, higher proportions of patients achieved ≤1, ≤6, and <15 eos/hpf with dupilumab vs placebo (26% vs 1%, 61% vs 5%, and 79% vs 7%, respectively). At W52, effects were maintained with continued dupilumab and increased from W16/24 in patients switching to dupilumab HE from placebo (Table). Dupilumab also improved percent change from baseline EoEHSS total grade and stage scores vs placebo at W16/24 (Table). At W52, improvements were maintained in the dupilumab group.

Conclusion

In this pooled analysis of two phase 3 studies, dupilumab improved histopathologic abnormalities of EoE compared with placebo during treatment initiation (W16/24) and maintenance (no evidence of relapse at W52), in children, adolescents, and adults with EoE. These improvements may be clinically meaningful as individual components of EoEHSS, as determined by EoEHSS grade/stage score, are implicated in altered esophageal motility, and persistent symptoms of EoE following diminution/ablation of eosinophil infiltrates. The safety profile of dupilumab was consistent with the overall known safety profile.

Table. Histopathology outcomes at Week 16/24 and Week 52 from the pooled population of the EoE KIDS and LIBERTY EoE TREET studies ****P<0.0001. aWeek 16/24 data are LS mean (95% CI); Week 52 data are mean (SD).bWeek 52 EoEHSS total score excluding lamina propria fibrosis. CI, confidence interval; EoEHSS, Eosinophilic Esophagitis Histologic Scoring System; eos/hpf, eosinophils per high-power field; LS, least squares; SD, standard deviation.
	Week 16/24		Week 52
	Pooled Dupilumab (N=159)	Pooled Placebo (N=152)​	Pooled Dupilumab-dupilumab (N=151)	Pooled Placebo-dupilumab (N=92)
Proportion of patients, % (95% CI)
≤6 eos/hpf	61**** (52.96, 68.63)	5 (2.30, 10.11)	72	62
<15 eos/hpf	79**** (71.42, 84.71)	7 (3.20, 11.77)	92	73
≤1 eos/hpf	26**** (19.18, 33.31)	1 (0.02, 3.61)	31	24
Mean percent change from baseline,a %
EoEHSS grade total scoreb	-62.7**** (-67.67, -57.72)	-3.2 (-8.46, 1.97)	-68.6 (13.8)	-63.5 (20.2)
EoEHSS stage total scoreb	-60.3**** (-65.48, -55.10)	-2.9 (-8.51, 2.71)	-66.7 (14.1)	-61.5 (20.2)

Disclosure

Collins MH: Alimentiv, Arena/Pfizer, AstraZeneca, Calypso Biotech, EsoCap Biotech, GSK, Receptos/Celgene/Bristol Myers Squibb, Regeneron Pharmaceuticals Inc., Inc., Shire/Takeda – advisory board/consultancy fees.
Chehade M: Adare Pharmaceuticals/Ellodi Pharmaceuticals, Allakos, AstraZeneca, Bristol Myers Squibb, Nexstone Immunology/Uniquity Bio, Phathom Pharmaceuticals, Recludix Pharma, Regeneron Pharmaceuticals Inc., Sanofi, Shire/Takeda – consultant. Adare Pharma Solutions/Ellodi, Allakos, AstraZeneca, Celgene, Danone, Regeneron Pharmaceuticals Inc., Shire/Takeda – research funding.
Dellon ES: AbbVie, Adare/Ellodi, Akesobio, Alfasigma, ALK, Allakos, Amgen, Apollo, Aqilion, Arena/Pfizer, Aslan, AstraZeneca, Avir, Biocryst, Bryn, Calypso, Celgene/Receptos/Bristol Myers Squibb, Celldex, Dr. Falk Pharma, EsoCap, Eupraxia, Ferring, GI Reviewers, GSK, Holoclara, Invea, Knightpoint, LucidDx, Morphic, Nexstone Immunology/Uniquity, Nutricia, Parexel/Calyx, Phathom, Regeneron Pharmaceuticals Inc., Revolo, Robarts/Alimentiv, Sanofi, Shire/Takeda, Target RWE, Upstream Bio – consulting fees. Adare/Ellodi, Allakos, Arena/Pfizer, AstraZeneca, Celgene/Receptos/Bristol Myers Squibb, Celldex, Eupraxia, Ferring, GSK, Meritage, Miraca, Nutricia, Regeneron Pharmaceuticals Inc., Revolo, Sanofi, Shire/Takeda – research funding. Allakos, Aqilion, Holoclara, Invea – educational grants.
Schlag C: Adare Pharmaceuticals Inc., AstraZeneca, Calypso, Dr. Falk Pharma, EsoCap GmbH, Regeneron Pharmaceuticals Inc. – consulting fees.
Fassan M: Amgen, Astellas, AstraZeneca, Bristol Myers Squibb, Diapath, Eli Lilly, GSK, Incyte, IQvia, Janssen Pharma, MSD, Novartis, Pierre Fabre, Roche, Pfizer, Sanofi – consulting fees.
Washington K: Discovery Life Sciences, Johnson & Johnson, Regeneron Pharmaceuticals Inc., Takeda – consultancy fees.
Xia C, Raphael BP, Radwan A: Regeneron Pharmaceuticals Inc. – employees and shareholders.
Cazeau C, Almansa C: Sanofi – employees, may hold stock and/or stock options in the company.

Clinical Case Summary

A 52-year-old male, liver-transplanted in 2014 for alcohol- and HCV-related cirrhosis (HCV eradicated in 2017 with DAAs), was evaluated in May 2024 due to low-grade evening fevers. His immunosuppression regimen included tacrolimus 1 mg b.i.d., with stable trough levels around 11.5 ng/mL. However, during a routine check-up, tacrolimus levels spiked to 27 ng/mL. The result was confirmed on repeat testing despite Tacrolimus discontinuation.

No changes in liver function were observed, and tacrolimus was temporarily discontinued. The patient was hospitalized and developed mild upper limb tremors. Erythrocytapheresis was performed due to suspected tacrolimus toxicity, reducing levels only modestly (from 22 to 21.2 ng/mL). Given the discrepancy between assay results and clinical context, the lab performed a dilutional linearity test, revealing non-linearity suggestive of assay interference.

Autoantibody screening (RF, ANA, ASMA, LKM, ANCA, etc.) was negative. However, treatment of the sample with heterophile antibody blocking reagent (HBR) significantly reduced tacrolimus concentrations, confirming heterophile antibody interference. The patient underwent plasmapheresis to eliminate interfering antibodies, which normalized tacrolimus readings. Unfortunately, he developed candidemia (Candida parapsilosis) and died from cardiovascular complications.

This case illustrates how heterophile antibodies may falsely elevate tacrolimus levels in immunoassays, potentially leading to inappropriate clinical decisions. Clinicians must consider assay interference when pharmacokinetics and clinical findings are discordant, and collaborate closely with laboratory services to ensure accurate therapeutic drug monitoring.