Chidamide

Chidamide (Tucidinostat) is a Chinese-developed oral HDAC inhibitor already approved in China, Japan, and Taiwan for relapsed/refractory peripheral T-cell lymphoma (PTCL). The node here tracks NCT05958719 - a Phase 2 trial of the CAMP regimen (chidamide + azacitidine + liposomal mitoxantrone + prednisone) in previously untreated nodal T-follicular-helper (TFH) lymphoma, a PTCL subtype (~15-20% of nodal PTCL in most series) defined by epigenetic dysregulation that makes it biologically primed for HDAC + hypomethylating-agent attack [1].

Not a novel compound. Chidamide was approved by China's NMPA (National Medical Products Administration, China's drug regulator) in late 2014 for relapsed/refractory PTCL - the first HDAC inhibitor approved by the NMPA, but not the first oral HDAC inhibitor globally (vorinostat/Zolinza was approved by the FDA in October 2006 for cutaneous T-cell lymphoma). It was later approved by Japan's PMDA (Pharmaceuticals and Medical Devices Agency, Japan's drug regulator) as Hiyasta for adult T-cell leukemia/lymphoma. It is sold as Epidaza by Shenzhen Chipscreen Biosciences; HUYA Bioscience historically held ex-China rights under the HBI-8000 code. The US never approved it: HUYA's Phase 3 TENERGY melanoma combo with nivolumab (NCT03097770) [9] failed, and the program shifted to academic-led combination work. The current trial (NCT05958719) [10] sits in Phase 2 with no FDA designation, no PDUFA clock, and no US registrational intent. Expected readout for the CAMP trial is not publicly disclosed; treat any 2026-2027 timing as speculative. The more commercially relevant near-term readout is the recently published JAMA Phase 3 of chidamide + R-CHOP in MYC/BCL2 double-expressor DLBCL [1], which is the first positive Phase 3 for an HDAC inhibitor in front-line aggressive lymphoma anywhere in the world.

HDACs (histone deacetylases) strip acetyl groups off histones - the protein spools that DNA wraps around. Stripping acetyls tightens the spool and silences genes, including tumor suppressors and genes that make cancer cells recognizable to the immune system. Chidamide blocks four of them (HDAC1, 2, 3, and 10), loosening the spool and reawakening those silenced genes [2]. The mechanism is well-validated in T-cell lymphomas specifically - vorinostat, romidepsin, belinostat, and chidamide are all approved for relapsed PTCL or cutaneous T-cell lymphoma, and TFH-PTCL in particular carries TET2, DNMT3A, and IDH2 mutations that cripple normal DNA methylation control [3]. That genetic profile is why pairing an HDAC inhibitor with the hypomethylating agent azacitidine has a real biological rationale rather than being a kitchen-sink combo: both arms attack the broken epigenetic machinery from different angles. Outside hematology the story is weaker - the JAMA DLBCL result [1] and a recent Phase 2 in HR+/HER2- breast cancer post-endocrine failure [4] show the drug travels, but the breast result is single-arm and the durable wins remain in T-cell disease.

NCT05958719 [10] is a Phase 2 study of the CAMP regimen (chidamide + azacitidine + liposomal mitoxantrone + prednisone) in previously untreated nodal TFH-cell lymphoma, run out of the Institute of Hematology & Blood Diseases Hospital in Tianjin. Primary endpoint is objective response rate (ORR) - standard for an exploratory PTCL combo but a soft endpoint that won't support registration on its own. There is no comparator arm; this is single-arm, single-center, which means any signal will need confirmation in a randomized study before it changes practice outside China. Enrollment specifics, current accrual, and readout timing are not reliably available in public registries. The broader chidamide trial portfolio is more interesting commercially: NCT05976997 (duvelisib + chidamide in newly diagnosed PTCL) [5] and NCT06928376 (venetoclax + CACAG regimen including chidamide in AML) [6] are probing whether the China-validated HDAC backbone can extend into new hematologic settings with modern partners. Additional academic-led azacitidine + chidamide + PD-1 combinations in R/R PTCL are in early stages but specific high-numbered NCT identifiers from 2025-2026 vintage should be independently verified before citation.

Our model puts this drug's chance of eventual approval at 9%. That starts from the historical approval rate for Phase 2 drugs in this area - about 21% - then adjusts up or down based on ten facts about the trial and the sponsor. Two things push the number down: the sponsor has a thin approval record, and earlier-phase results were weak. Two things push it up - the trial's non-randomized design and its open-label blinding - but not enough to offset the negatives.

Efficacy risk: TFH-PTCL is a small, heterogeneous subset (~15-20% of nodal PTCL) and single-arm ORR readouts have repeatedly oversold in PTCL - romidepsin's Ro-CHOP Phase 3 in front-line PTCL famously missed PFS despite encouraging Phase 2 data. Safety risk: HDAC inhibitors carry predictable hematologic toxicity (thrombocytopenia, neutropenia) and QTc prolongation; stacking chidamide on top of liposomal mitoxantrone and azacitidine means real cumulative myelosuppression, and the linperlisib + chidamide Phase 1 [8] flagged exactly that pattern. Execution risk: single-center Chinese academic trials often read out slowly and don't translate cleanly into US registrational packages - HUYA's failure to land chidamide in the US (TENERGY melanoma combo with nivolumab missed) is the cautionary tale. Commercial risk: even a positive readout has near-zero ex-China commercial implication absent a Western partner. Chipscreen is publicly listed in Shanghai (688321.SS) but has no active US development program for this indication. Pricing makes the gap concrete: chidamide in China runs approximately CNY 1,400/month (~$190/month) versus romidepsin (Istodax) at roughly $30,000-40,000 per cycle in the US - a structural 40-50x gap that caps the global revenue story absent major price repositioning by a Western partner. As of this writing, no Western pharma has publicly disclosed licensing interest in chidamide following the 2026 DLBCL Phase 3 readout.

Watch, don't act. The interesting chidamide signal this cycle isn't this CAMP trial - it's the JAMA Phase 3 in MYC/BCL2 double-expressor DLBCL [1] (DLBCL = diffuse large B-cell lymphoma; 'double-expressor' = an aggressive subtype defined by overexpression of two cancer-driving proteins, MYC and BCL2), which is the first time an HDAC inhibitor has won in front-line aggressive B-cell lymphoma and could shift how the field thinks about epigenetic combos beyond T-cell disease. For the TFH-PTCL trial specifically, the data point that matters is ORR with durability (median DoR > 12 months) in ≥30 patients, ideally with circulating tumor DNA clearance - anything less is single-center noise, especially given the CHIPEL R/R benchmark of 28% ORR (50% in the AITL/TFH subset) [11]. Check back when CAMP regimen ORR data show up at ASH 2026 or in a peer-reviewed journal. The commercial story belongs to Shenzhen Chipscreen Biosciences (688321.SS), and the question worth tracking is whether they license ex-China rights to a Western developer on the back of the DLBCL Phase 3 - that would be the catalyst that pulls chidamide into the global HDAC conversation alongside romidepsin and belinostat. No such licensing announcement has been made publicly as of this writeup.