Pairing RMR1's young-HSC transplant with serial CHIP surveillance and triggered αKG + low-dose decitabine clone elimi...

IF young-donor (8–12 week) C57BL/6J HSC transplantation (as performed in RMR1) is combined with serial post-transplant clonal surveillance using a cost-effective, scalable error-corrected amplicon sequencing panel targeting canonical CHIP driver loci (Tet2, Dnmt3a, Asxl1, Jak2) at 3-month intervals, AND any clone exceeding 2% variant allele frequency (VAF) triggers targeted pharmacological elimination via cell-permeable α-ketoglutarate (αKG; 1–2 g/kg/day oral supplementation) combined with a sub-myeloablative dose of the hypomethylating agent decitabine (0.1 mg/kg i.p., 5-day cycle) to selectively re-sensitize epigenetically altered mutant clones to apoptosis while sparing wild-type HSCs,

THEN aged (22–24 month) C57BL/6J recipient mice will maintain ≥90% wild-type clonal composition in peripheral blood and bone marrow HSC compartment (measured by VAF ≤2% at all surveilled loci) through 6 months post-transplant, with preservation of multilineage output, reduction in clonal diversity loss (Shannon entropy), and suppression of pro-inflammatory myeloid skewing (IL-6, IL-1β plasma levels), as compared to RMR1 HSC-transplant-only controls receiving no post-transplant clonal intervention,

BECAUSE:

1. Young HSC grafts reconstituting an aged bone marrow niche are exposed to an inflammatory, TGF-β-rich, and metabolically altered microenvironment that historically selects for Tet2- and Dnmt3a-mutant clones with fitness advantages; surveillance using a scalable CHIP assay enables early detection of emergent clones before they dominate the graft (Cost-effective and scalable clonal hematopoiesis assay)[https://doi.org/10.1101/2023.11.08.23298270].
2. TET2 is a 2-oxoglutarate (α-ketoglutarate)-dependent dioxygenase; TET2-loss-of-function mutant HSCs operate under a state of functional αKG insufficiency for hydroxymethylation reactions, conferring hypermethylation-driven transcriptional silencing of differentiation-inducing genes and granting competitive self-renewal advantage; exogenous αKG supplementation can restore the thermodynamic driving force for residual TET2 activity and partially reverse aberrant hypermethylation in heterozygous Tet2-mutant cells [SPECULATIVE — mechanistically grounded but untested in post-transplant context].
3. Sub-therapeutic decitabine (below cytotoxic threshold for wild-type HSCs) preferentially depletes cells with already-hypermethylated genomes characteristic of Dnmt3a- and Tet2-mutant clones by causing replication-stress-induced apoptosis only in cells dependent on DNA methylation for silencing tumor suppressor loci [SPECULATIVE].
4. The combination of αKG and low-dose decitabine is synergistic: αKG reduces the methylation density that decitabine must act upon, lowering the decitabine dose required to trigger apoptosis in mutant clones below the threshold that harms wild-type HSCs, thereby creating a therapeutic window for selective mutant clone elimination [SPECULATIVE — requires Phase 1 validation]. 5...

SENS category: OncoSENS

Key references: • doi.org/10.1101/2023.11.08.23298270]. • doi.org/10.1101/2023.11.08.23298270], • doi.org/10.1101/2023.11.08.23298270]