Metagenomic Deep Sequencing Identifies Gene Mutations Associated with Chemotherapeutic Resistance in Vitreoretinal Lymphoma
Synopsis
In 49 patients with vitreoretinal lymphoma (VRL) confirmed by cytopathology, immunohistochemistry, flow cytometry, and/or MYD88 PCR, host-genome metagenomic deep sequencing (MDS) of intraocular specimens cross-referenced against the Catalogue of Somatic Mutations in Cancer identified eight gene mutations associated with chemotherapeutic resistance in six specimens from four patients, including methotrexate-resistance-associated mutations in four specimens from three patients, and in one patient serial sampling at initial vitrectomy and two subsequent recurrences revealed distinct resistance-associated mutations at each time point; that patient died despite multi-agent therapy including rituximab, consolidation regimens, and lenalidomide, whereas the other three patients remained in long-te
Interpretation
Specific gene mutations associated with chemotherapeutic resistance can be harbored by VRL. Whether resistance-associated mutations exist in VRL was previously unclear; this study used host-genome MDS with COSMIC cross-referencing and localized such mutations in four of 49 patients. Based on 49 patients with VRL confirmed by cytopathology, immunohistochemistry, flow cytometry, and/or MYD88 PCR, with eight resistance-associated mutations found across six specimens; a descriptive sequencing finding.
Mutations associated with methotrexate resistance can be detected in VRL, and methotrexate is the mainstay of VRL treatment. Links resistance-associated mutations specifically to methotrexate, the mainstay of VRL therapy, suggesting a molecular correlate of resistance. Four specimens from three patients harbored methotrexate-resistance-associated mutations; small sample, an initial observation.
Different resistance-associated mutations can be detected at different time points in the same patient. Serial sampling from the initial vitrectomy and two subsequent recurrences showed a changing resistance-associated mutation profile over time, which the text suggests may reflect clonal selection, treatment pressure, or variable detection sensitivity. Longitudinal sampling in a single patient; the text frames this as 'may reflect' rather than a causal claim.
Ocular fluid is easily sampled and can be used to detect different mutations associated with tumor recurrence or persistence. Proposes the feasibility of monitoring resistance-associated mutations through ocular fluid sampling and, on that basis, developing targeted PCR assays for the identified resistance genes. An application direction proposed from this cohort's sampling and sequencing experience; targeted PCR assays remain at the 'establish a foundation' stage and were not validated in this paper.
Perspective
The results apply to patients with VRL confirmed by cytopathology, immunohistochemistry, flow cytometry, and/or MYD88 PCR, with host-genome sequencing of intraocular specimens; their value lies in establishing a foundation for developing targeted PCR assays for the identified resistance genes and in suggesting that ocular fluid sampling can monitor mutations associated with tumor recurrence or persistence, potentially informing prognosis and treatment decisions.
Why different resistance-associated mutations were detected at different time points in the same patient remains open; the text suggests this may reflect clonal selection, treatment pressure, or variable detection sensitivity, which still need to be distinguished. The link between resistance-associated mutations and clinical resistance requires validation in larger cohorts. The feasibility of targeted PCR assays remains to be established and evaluated. This is summary-level information lacking figures and details on specific mutation sites and frequencies, which limits a complete mapping of the mutation profile.