Researchers at the University of Pennsylvania have identified an antagonistic relationship among three histone methyltransferases — NSD2, SETD2, and EZH2 — that controls whether lung tumors can evade immune destruction, according to a study published September 14 in Nature Communications. The findings establish a mechanistic rationale for targeting NSD2 in KRAS-driven lung cancer.
The work, led by David Feldser at Penn's Perelman School of Medicine and Abramson Family Cancer Research Institute, centers on how competing modifications to a single site on histone H3 — lysine 36 — determine whether repetitive genomic sequences remain silenced or are transcribed. When NSD2 deposits a dimethyl mark at this site, it supports the repressive enzyme EZH2 in keeping those sequences quiet. When NSD2 activity is reduced, a SETD2-dependent mechanism limits EZH2's ability to maintain that repression, allowing repetitive elements to be transcribed and accumulate as cytoplasmic double-stranded RNA (dsRNA). The dsRNA triggers an antiviral-like innate immune response — a phenomenon known as viral mimicry — that promotes tumor clearance.
Genetic and pharmacologic evidence in a KRAS lung cancer model
The researchers used LSL-H3K36M transgenic mice in a KRAS-driven lung cancer system. H3K36M is an oncogenic histone mutation that acts as a dominant inhibitor SETD2 and other H3K36 methyltransferases, particularly NSD2. Expressing H3K36M phenocopied the effects of directly attenuating NSD2 genetically, identifying NSD2 as the critical node in the pathway. Pharmacologic inhibition of NSD2 produced the same downstream immune activation, demonstrating that the mechanism is accessible to small-molecule intervention. Critically, the study showed that SETD2 activity was required for all downstream effects: even when NSD2 was reduced, loss of SETD2 abrogated dsRNA accumulation and immune activation, placing SETD2 as an obligate intermediary between NSD2 inhibition and EZH2 de-repression of repetitive elements.
Translational context
The preclinical findings arrive as NSD2 inhibitors are advancing in clinical development, though not yet in lung cancer. K36 Therapeutics is evaluating KTX-1001, an oral NSD2/MMSET inhibitor, in a Phase I trial (NCT05651932) enrolling patients with relapsed/refractory multiple myeloma, where NSD2 is amplified due to the t(4;14) chromosomal translocation. A second K36 Therapeutics compound, KTX-2001, is being evaluated in a Phase I dose-escalation study (NCT07103018) in metastatic castration-resistant prostate cancer. Neither program currently targets KRAS-driven lung cancer, representing a gap between the Penn findings and existing clinical activity.