Combining MYD88 L265P mutation detection and clonality determination on CSF cellular and cell‐free DNA improves diagnosis of primary CNS lymphoma

Clotilde Bravetti (1) , Michaël Degaud (1) , Marine Armand (1) , Elise Sourdeau (1) , Karima Mokhtari (1) , Karim Maloum (1) , Jennifer Osman (1) , Patricia Verrier (1) , Caroline Houillier (2) , Damien Roos‐weil (1) , Carole Soussain (3) , Sylvain Choquet (1) , Khe Hoang‐xuan (2) , Magali Le Garff‐tavernier (1) , Jérôme Alexandre Denis (1, 4) , Frédéric Davi (1)

1 CHU Pitié-Salpêtrière [AP-HP]
2 ICM - Institut du Cerveau = Paris Brain Institute
3 U932 - Immunité et cancer
4 CRSA - Centre de Recherche Saint-Antoine

Diagnosis of primary central nervous system lymphoma (PCNSL) is challenging, and although brain biopsy remains the gold standard, cerebrospinal f luid (CSF) con-stitutes a less invasive source of lymphomatous biomarkers. In a retrospective co-hort of 54 PCNSL cases tested at diagnosis or relapse, we evaluated the contribution of immunoglobulin heavy chain (IGH) gene clonality and MYD88 L265P detection on both CSF cell pellets and supernatants, in comparison with cytology, f low cy-tometry, interleukin (IL)-10 and IL-6 quantification. Clonality assessment included a new assay to detect partial IGH-DJ rearrangements. Clonal IGH rearrangements a nd/or MYD88 L265P mutation were detected in 27 (50%) cell pellets and 24 (44%) supernatant cell-free (cf) DNA. Combining analyses on both compartments, 36 (66%) cases had at least one detectable molecular marker, present only in cf DNA for 9 (16%) of them. While cytology and f low cytometry were positive in only 7 (13.0%) and 9 (17.3%) cases respectively, high IL-10 levels were observed in 36 (66.7%) cases. Overall, taking into account molecular and cytokine results, 46/54 (85%) cases had at least one lymphomatous biomarker detectable in the CSF. These results show that this combination of biomarkers evaluated on both cell pellet and supernatant CSF fractions improves significantly the biological diagnosis of PCNSL.

Keywords: primary central nervous system lymphoma; PCR; polymerase chain reaction; RFLP; restriction fragment length polymorphism; SHM; CBA; cytometric bead array cfDNA; cell-free DNA CSF; cerebrospinal fluid ctDNA; circulating tumor DNA ddPCR; digital droplet polymerase chain reaction DLBCL; diffuse large B-cell lymphoma FCM; flow cytometry FR; framework regions IG; immunoglobulin IGH; immunoglobulin heavy chain IL; interleukins LOC; lymphomes oculo-cerebraux NGS; next-generation sequencing PCNSL; primary central nervous system lymphoma PCR; polymerase chain reaction RFLP; restriction fragment length polymorphism SHM; somatic hypermutation clonality; CNS lymphoma; CSF; MYD88; cytometric bead array; cfDNA; cell-free DNA; cerebrospinal fluid; ctDNA; circulating tumor DNA; ddPCR; digital droplet polymerase chain reaction; DLBCL; diffuse large B-cell lymphoma; FCM; flow cytometry; FR; framework regions; IG; immunoglobulin; IGH; immunoglobulin heavy chain; IL; interleukins; LOC; lymphomes oculo-cerebraux; NGS; next-generation sequencing; PCNSL

Domains: Human genetics

Clotilde Bravetti, Michaël Degaud, Marine Armand, Elise Sourdeau, Karima Mokhtari, et al.. Combining MYD88 L265P mutation detection and clonality determination on CSF cellular and cell‐free DNA improves diagnosis of primary CNS lymphoma. British Journal of Haematology, 2023, 201 (6), pp.1088 - 1096. ⟨10.1111/bjh.18758⟩. ⟨hal-04515614⟩