A Proliferative Relapse-State Program in Pediatric B-ALL Is Not a Baseline Prognostic Signature
Relapsed pediatric B-cell acute lymphoblastic leukemia remains clinically hard because recurrence is not only a return of leukemia burden, but a selected biological state. We reanalyzed 49 paired diagnosis-relapse marrow expression profiles from GEO series GSE28460 and challenged the resulting relapse program in the independent diagnostic cohort GSE7440. Across 21,755 annotated genes in GSE28460, 505 genes changed at relapse at FDR < 0.10 with an absolute mean paired log2 fold-change above 0.35. The relapse program was dominated by cell-cycle and DNA-replication biology, with cell division, sister chromatid cohesion, mitotic nuclear division, DNA replication, and G1/S transition as the strongest enriched processes. Curated signature analysis recovered increased cell-cycle scoring and decreased glucocorticoid-response scoring at relapse. In 59 GSE7440 diagnosis samples with outcome labels, the top relapse-up minus relapse-down program did not distinguish later relapse from complete continuous remission (AUC 0.48; Mann-Whitney p = 0.80). This negative external test sharpens the interpretation: the signal is a relapse-state program, not a baseline bulk prognostic signature.
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This work reanalyzes paired diagnosis–relapse pediatric B-ALL bulk microarrays (GSE28460; n=49 pairs) to derive a relapse-associated differential-expression program and then tests whether that program is prognostic when scored at diagnosis in an independent cohort with outcome labels (GSE7440; n=59). The paired design is an appropriate strength for defining relapse-associated changes, and the dominant signal reported—upregulation of proliferation/cell-cycle/DNA-replication genes with reduced glucocorticoid-response scoring—is biologically plausible and consistent with many relapse narratives. The key contribution is the explicit negative external test: a simple relapse-up minus relapse-down score at diagnosis fails to distinguish eventual relapsers from continuous remission (AUC ~0.48), supporting the paper’s central interpretive claim that the program reflects a relapse state rather than a baseline prognostic signature. The main uncertainties are methodological and interpretive rather than conceptual. The relapse signature thresholding (FDR<0.10 plus an effect-size cutoff) is reasonable but lenient, and the manuscript excerpt does not provide enough detail on preprocessing, batch handling, probe-to-gene collapsing, paired-model specification, and whether platform differences or covariates (subtype, time-to-relapse, treatment era) were addressed—any of which could affect both the gene list and the external scoring. The negative prognostic result is informative but not definitive: the external cohort size is modest; outcome labeling and follow-up heterogeneity can attenuate AUC; and a single linear score may underperform alternative, pre-registered models (e.g., penalized logistic regression) even if some prognostic information exists. The conclusion that the relapse program is not a baseline bulk prognostic signature is directionally justified by the reported external test, but it should be framed as “not supported as a robust prognostic signature under this simple