830P - Isolation of cell-free DNA of patients with mucosa-associated lymphoid tissue (MALT) lymphoma

Background

To evaluate treatment efficacy for gastric extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT-lymphoma), histologic assessment via multiple gastric biopsies every 3 months constitutes the current gold standard. Currently, non-invasive diagnostic measures including PET-MRI to monitor therapy response in MALT lymphoma patients remain experimental for the time-being. While liquid biopsies isolating cell-free DNA (cfDNA) are used in other tumor entities for diagnostic and treatment monitoring measures, no data for gastric MALT-lymphoma have been published so far. Thus, we performed a pilot series to assess cfDNA in therapy-naïve gastric MALT-lymphoma patients.

Methods

For the isolation of cfDNA, blood from patients with MALT lymphoma was collected using PAXgene Blood ccfDNA tubes (Qiagen). cfDNA was isolated using the QIAamp Circulating Nucleic Acid Kit (Qiagen). DNA concentration was measured using fluorescence quantification (Qubit, Thermo Fisher). Quantitative data were compared to 68-Ga-Pentixafor-PET/MRI performed within 4 weeks assessing active lymphoma volumes. Clinical parameters were obtained by chart review.

Results

A total of 15 patients (4 males, 11 females) with MALT lymphoma at a median age of 64 years (range: 44-79) were included in this study. cfDNA could be isolated in all patients with a median concentration of 5.4ng/ml plasma (range: 3.6-12.4ng/ml). Compared to a healthy control cohort (n=5), cfDNA levels were significantly increased in MALT lymphoma patients (3.8ng/ml vs. 5.9ng/ml, p=0.025). In 12/15 patients, a follow-up blood draw could be obtained after a median 3.3 months (range 0.9-7.0 months). cfDNA levels remained stable during that time period with a mean concentration of 5.7ng/ml at baseline and 6.3ng/ml at follow-up (p>0.05). Correlation between metabolically active tumor volume and cfDNA concentration will be reported as soon as radiologic reclassification is completed.

Conclusions

cfDNA may be used as a non-invasive biomarker for disease monitoring in patients with MALT lymphoma.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

the authors.

Funding

The financial support by the Austrian Federal Ministry for Digital and Economic Affairs, the National Foundation for Research, Technology and Development and the Christian Doppler Research Association is gratefully acknowledged.

Disclosure

B. Kiesewetter-Wiederkehr: Financial Interests, Personal, Invited Speaker: Ipsen, Novartis, MSD, Advanced Accelerator Applications (AAA), Boehringer Ingelheim, Eli Lilly; Financial Interests, Personal, Advisory Board: Ipsen, Roche, Eli Lilly, MSD; Non-Financial Interests, Project Lead, Young Hematologist and Oncologists Group Austria (YHOGA): Austrian Society for Hematology and Medical Oncology (OeGHO). A.S. Berghoff: Financial Interests, Personal, Invited Speaker: Roche, Bristol Myers Squibb, Merck, AstraZeneca; Financial Interests, Personal, Advisory Board: Daiichi Sankyo; Financial Interests, Institutional, Research Grant: Daiichi Sankyo, Roche. M. Preusser: Financial Interests, Personal, Advisory Board: Bayer, Bristol Myers Squibb, Novartis, Gerson Lehrman, CMC Contrast, GSK, Mundipharma, Roche, BMJ Journals, MedMedia, AstraZeneca, AbbVie, Lilly, Medahead, Daiichi Sankyo, Sanofi, Merck Sharp & Dohme, Tocagen, Adastra, Gan & Lee Pharmaceuticals; Financial Interests, Institutional, Research Grant, Clinical Trials and research: Boehringer-Ingelheim, Bristol Myers Squibb, Roche, Daiichi Sankyo, Merck Sharp & Dohme, Novocure, GSK, AbbVie; Financial Interests, Institutional, Coordinating PI: PharmaMar; Non-Financial Interests, Leadership Role, Brain Tumor Group Chair (current): EORTC; Non-Financial Interests, Leadership Role, EANO Past-President (current): EANO; Non-Financial Interests, Other, Member Multi-Site Guideline Advisory Group: ASCO. M. Raderer: Financial Interests, Personal, Other, Honoraria: BeiGene, Celgene, Eli Lilly, Gilead, Galapagos, Ipsen, Novartis, Roche. All other authors have declared no conflicts of interest.