The histone deacetylase (HDAC) inhibitors market is experiencing significant momentum, with DelveInsight's latest analysis projecting substantial growth across the seven major markets through 2034. This expansion is being driven by a robust pipeline of next-generation agents and innovative combination therapies targeting various cancer types and emerging non-oncology indications.
Active Pipeline Drives Market Growth
The HDAC inhibitor pipeline remains highly active, with several promising candidates advancing through clinical development. Abexinostat, developed by Xynomic Pharmaceuticals, has reached Phase III development for renal cell carcinoma, representing a significant expansion of HDAC inhibitors into solid tumor applications. The oral, broad-spectrum HDAC inhibitor, originally developed by Pharmacyclics and licensed by Xynomic in 2017, has demonstrated encouraging activity in both blood cancers and solid tumors across multiple Phase I to III clinical trials worldwide.
Viriom's Quisinostat is progressing through Phase II trials for uveal melanoma, while Entinostat, developed through a partnership between EOC Pharma and Syndax Pharmaceuticals, is being explored in Hodgkin lymphoma. These developments highlight the expanding therapeutic applications of HDAC inhibitors beyond their traditional hematologic cancer indications.
Recent Market Entrants Show Therapeutic Diversity
The market has welcomed several new entrants that demonstrate the versatility of HDAC inhibitors. DUVYZAT (givinostat) represents a notable expansion beyond oncology, having gained approval for treating Duchenne muscular dystrophy in patients aged 6 and above. In April 2025, Italfarmaco announced that the Committee for Medicinal Products for Human Use (CHMP) of the European Medicines Agency issued a positive opinion on DUVYZAT, with the drug also being evaluated in Phase III trials for Becker muscular dystrophy and Phase II trials for polycythemia vera.
HIYASTA (tucidinostat/HBI-8000) has established itself as an important treatment option for T-cell lymphomas. This oral HDAC Class I inhibitor is approved in Japan as monotherapy for certain subtypes of relapsed or refractory T-cell non-Hodgkin's lymphoma, specifically adult T-cell leukemia-lymphoma and peripheral T-cell lymphoma. HUYABIO International is currently conducting a multinational Phase III trial evaluating HIYASTA in combination with nivolumab for previously untreated metastatic or unresectable malignant melanoma.
Regulatory Recognition and Fast Track Designations
The therapeutic potential of HDAC inhibitors has gained significant regulatory recognition. In September 2019, Xynomic announced that the FDA granted Fast Track Designation to abexinostat as monotherapy for fourth-line treatment of relapsed or refractory follicular lymphoma. The FDA had previously granted Fast Track Designation for abexinostat in combination with pazopanib for first- or second-line therapy in renal cell carcinoma.
Similarly, HIYASTA has received multiple regulatory designations, including orphan drug designation from the Japanese Ministry of Health, Labour and Welfare for relapsed/refractory adult T-cell leukemia-lymphoma in September 2020 and for peripheral T-cell lymphoma in December 2015.
Mechanism of Action and Therapeutic Rationale
HDAC inhibitors work through a sophisticated mechanism targeting epigenetic regulation. Histone deacetylases remove acetyl groups from both histone and non-histone proteins, and since acetylation of histones is linked to an open chromatin structure and active gene transcription, HDAC activity leads to histone deacetylation and epigenetic suppression of gene expression. HDAC inhibitors show clinical effects through several mechanisms, including changes in gene expression of cell cycle and apoptotic proteins, acetylation of other proteins involved in cell growth and survival, effects on angiogenesis, aggresome formation, and DNA repair.
There are 18 known HDACs, divided into two major groups and four classes based on their cellular location, homology, enzyme mechanism, sequence of discovery, and histone substrate specificity. The first group includes zinc-dependent HDACs comprising Class I (HDAC1, -2, -3, -8), Class II (IIa: HDAC4, -5, -7, -9; IIb: HDAC6, -10), and Class IV (HDAC11). The second group includes Class III HDACs (sirtuins, SIRT1–7), which rely on NAD+ for their enzymatic activity.
Market Dynamics and Challenges
The HDAC inhibitors market continues to expand largely due to the rising prevalence of cancer worldwide and the need for more targeted therapies with better safety profiles. Ongoing clinical trials are exploring HDAC inhibitors in combination with other therapies, such as immune checkpoint inhibitors, proteasome inhibitors, and traditional chemotherapeutics. These combination approaches aim to overcome resistance and enhance efficacy, creating more opportunities for market growth.
However, the market faces several challenges. Many HDAC inhibitors are associated with toxicity issues such as fatigue, gastrointestinal disturbances, and thrombocytopenia, which limit broader adoption. Competition from newer targeted therapies and immuno-oncology drugs also puts pressure on the HDAC inhibitor segment. Several compounds have failed in late-stage trials due to lack of efficacy, leading to cautious investor sentiment and prioritization of combination rather than monotherapy approaches.
Recent Clinical Developments
Recent months have seen significant clinical activity in the HDAC inhibitor space. In May 2025, the University of Miami, in collaboration with Viriom, initiated a Phase II clinical trial in the US (NCT06932757) to evaluate an oral therapy for patients with uveal melanoma who have undergone at least one prior line of treatment. In April 2025, Xynomic Pharmaceuticals concluded a Phase I/II clinical trial in the United States (NCT03939182), evaluating a combination oral therapy for patients with Diffuse Large B-cell Lymphoma and Mantle Cell Lymphoma who had received at least one prior line of treatment.
Future Market Outlook
Looking ahead, market dynamics are expected to be shaped increasingly by precision oncology trends and biomarker-driven patient selection, allowing more effective targeting of responders. The anticipated launch of emerging therapies is poised to transform the HDAC inhibitors market landscape in the coming years. As these cutting-edge therapies continue to mature and gain regulatory approval, they are expected to reshape the market landscape, offering new standards of care and unlocking opportunities for medical innovation and economic growth.
Novel formulations, selective HDAC isoform inhibitors, and expansion into non-oncology indications such as neurodegenerative or inflammatory diseases may further diversify the market and drive its next phase of growth. The market encompasses key indications including Multiple Myeloma, Peripheral T-cell Lymphoma, Cutaneous T-cell Lymphoma, and Amyotrophic Lateral Sclerosis, with leading companies such as Xynomic Pharmaceuticals, Viriom, EOC Pharma, Syndax Pharmaceuticals, and Jubilant Therapeutics developing novel HDAC inhibitors for future market availability.
