Background
Randomized, double-blind, placebo-controlled phase 3 (DEB), 40 centers in China. N=423 newly diagnosed MYC/BCL2 double-expressor DLBCL (DEL), median age 63. DEL carries poor prognosis after standard R-CHOP. Tucidinostat (chidamide) = oral selective HDAC inhibitor dually targeting MYC and BCL2 oncoproteins.
Results
Interventions and follow up: Arm A: tucidinostat 20 mg PO days 1, 4, 8, 11 q21d + R-CHOP ×6; responders in CR continued tucidinostat maintenance up to 24 weeks
Arm B: placebo + R-CHOP ×6; placebo maintenance
Primary endpoint: EFS
mFollow up: 41.3 mo
Results: EFS: HR 0.72 (95% CI 0.54–0.96), P=.02; 2-yr EFS 60.3% vs 50.5%
CR rate: 73.0% vs 61.8% (difference 11.1%, 95% CI 2.3–20.0%)
OS: NR (secondary; not reported at this analysis)
Arm B: placebo + R-CHOP ×6; placebo maintenance
Primary endpoint: EFS
mFollow up: 41.3 mo
Results: EFS: HR 0.72 (95% CI 0.54–0.96), P=.02; 2-yr EFS 60.3% vs 50.5%
CR rate: 73.0% vs 61.8% (difference 11.1%, 95% CI 2.3–20.0%)
OS: NR (secondary; not reported at this analysis)
Adverse events
Overall: increased toxicity with tucidinostat vs placebo, mainly hematologic; generally manageable with supportive care
Grade ≥3 rates: NR in primary report
Discontinuation: NR
Grade ≥3 rates: NR in primary report
Discontinuation: NR
Conclusions
Tucidinostat + R-CHOP significantly improved EFS and CR rate vs R-CHOP alone in newly diagnosed double-expressor DLBCL. First phase 3 trial to show benefit of an epigenetic modulator in DLBCL, defining a new first-line option for this high-risk subgroup.
Key Limitations
Conducted entirely in China — generalizability to other populations uncertain (flagged in accompanying JAMA editorial). DEL defined by IHC cutoffs with known interobserver variability. EFS is a composite (includes new therapy for residual disease); OS benefit not demonstrated. Sponsor (Chipscreen) involved in design/analysis.
Clinical Context
Tucidinostat is NMPA-approved in China (PTCL; HR+ breast cancer with exemestane) but not FDA/EMA-approved. Current 1L standard for high-risk DLBCL (IPI ≥2) is pola-R-CHP per POLARIX; DEL patients have no dedicated approved regimen. DEB positions HDAC inhibition as the first DEL-directed phase 3 success; confirmation outside China awaited.