Network-based assessment of HDAC6 activity predicts preclinical and clinical responses to the HDAC6 inhibitor ricolinostat in breast cancer.

Inhibiting individual histone deacetylase (HDAC) is emerging as well-tolerated anticancer strategy compared with pan-HDAC inhibitors. Through preclinical studies, we demonstrated that the sensitivity to the leading HDAC6 inhibitor (HDAC6i) ricolinstat can be predicted by a computational network-based algorithm (HDAC6 score). Analysis of ~3,000 human breast cancers (BCs) showed that ~30% of them could benefice from HDAC6i therapy. Thus, we designed a phase 1b dose-escalation clinical trial to evaluate the activity of ricolinostat plus nab-paclitaxel in patients with metastatic BC (MBC) (NCT02632071). Study results showed that the two agents can be safely combined, that clinical activity is identified in patients with HR+/HER2- disease and that the HDAC6 score has potential as predictive biomarker. Analysis of other tumor types also identified multiple cohorts with predicted sensitivity to HDAC6i's. Mechanistically, we have linked the anticancer activity of HDAC6i's to their ability to induce c-Myc hyperacetylation (ac-K148) promoting its proteasome-mediated degradation in sensitive cancer cells.

Preclinical assessment of histone deacetylase inhibitor quisinostat as a therapeutic agent against esophageal squamous cell carcinoma.

Esophageal squamous cell carcinoma (ESCC) is one of the most serious life-threatening malignancies. Although chemotherapeutic targets and agents for ESCC have made much progress recently, the efficacy is still unsatisfactory. Therefore, there is still an unmet medical need for patients with ESCC. Here, we report the expression status of HDAC1 in human ESCC and matched paracancerous tissues, and the results indicated that HDAC1 was generally upregulated in ESCC specimens. Furthermore, we comprehensively assessed the anti-ESCC activity of a highly active HDAC1 inhibitor quisinostat. Quisinostat could effectively suppress cellular viability and proliferation of ESCC cells, as well as induce cell cycle arrest and apoptosis even at low treatment concentrations. The effectiveness was also observed in KYSE150 xenograft model when quisinostat was administered at tolerated doses (3 mg/kg and 10 mg/kg). Meanwhile, quisinostat also had the ability to suppress the migration and invasion (pivotal steps of tumor metastasis) of ESCC cells. Western blot analysis indicated that quisinostat exerted its anti-ESCC effects mainly through blockade of Akt/mTOR and MAPK/ERK signaling cascades. Overall, HDAC1 may serve as a potential therapeutic target for ESCC, and quisinostat deserves to be further assessed as a promising drug candidate for the treatment of ESCC.

Assessment of new HDAC inhibitors for immunotherapy of malignant pleural mesothelioma.

Background: Malignant pleural mesothelioma (MPM) is a very rare and highly aggressive cancer of the pleura associated in most cases with asbestos exposure. To date, no really efficient treatments are available for this pathology. Recently, it has been shown that epigenetic drugs, particularly DNA methylation or histone acetylation modulating agents, could be very efficient in terms of cytotoxicity for several types of cancer cells. We previously showed that a hypomethylating agent (decitabine) and a histone deacetylase inhibitor (HDACi) (valproic acid (VPA)) combination was immunogenic and led to the induction of an anti-tumor immune response in a mice model of mesothelioma. However, VPA is not very specific, is active at millimolar concentrations and is responsible for side effects in clinic. To improve this approach, we studied four newly synthetized HDACi, two hydroxamates (ODH and NODH) and two benzamides (ODB and NODB), in comparison with VPA and SAHA. We evaluated their toxicity on immune cells and their immunogenicity on MPM cells in combination with decitabine. Results: All the tested HDACi were toxic for immune cells at high concentrations. Combination with decitabine increased toxicity of HDACi only towards T-cell clone. A decrease in the proportion of regulatory T cells and natural killer cells was observed in particular with VPA and ODH. In MPM cells, all HDACi combinations induced NY-ESO-1 cancer testis antigen (CTA) expression and the recognition of the treated cells by a NY-ESO-1 specific T-CD8 clone. However, for MAGE-A1, MAGE-A3 and XAGE-1b mRNA expression, the results obtained depended on the HDACi used and on the CTA studied. Depending on the MPM cell line studied, molecules alone increased moderately PD-L1 expression. When combined, a higher stimulation of this immune check point inhibitor expression was observed. Decitabine-induced anti-viral response seemed to be inhibited in the presence of HDACi. Conclusions: This work shows that the combination of decitabine and HDACi could be of interest for MPM immunotherapy. However, this combination induced PD-L1 expression which suggests that an association with anti-PD-L1 therapy should be performed to induce an efficient anti-tumor immune response.

An exploratory cost-effectiveness analysis of systemic treatments for cutaneous T-cell lymphoma.

PURPOSE: To conduct an exploratory cost-effectiveness analysis of systemic treatment options for more advanced cutaneous T-cell lymphoma (CTCL). METHODS: A cost-effectiveness model compared systemic bexarotene, denileukin diftitox, interferon-α, methotrexate, pralatrexate, romidepsin, vorinostat, and extracorporeal photopheresis (ECP) treatment of CTCL. Treatment effectiveness data were extracted from published studies and/or US product labeling. Overall response, the primary effectiveness measure, was defined as the proportion of patients achieving complete or partial response. Costs were based on wholesale acquisition cost (medications) and Medicare reimbursement rates (ECP, medication administration, adverse drug effect treatment). The perspective of the study was from that of a payer. RESULTS: Methotrexate was the lowest cost option [mean $436; standard deviation (SD) $284], followed by interferon-α (mean $32,174; SD $27,582), denileukin difitox (mean $40,107; SD $18,598), and ECP (mean $40,985; SD $45,633). Other treatments had costs greater than $50,000, ranging from vorinostat ($65,958; SD $40,637) to bexarotene ($239,424; SD $178,881). The incremental cost-effectiveness ratio per successfully treated patient was $396,725 (interferon) and $213,416 (ECP). Denileukin diftitox, romidepsin, and vorinostat were less effective and cost more than methotrexate. CONCLUSION: Methotrexate is the most cost-effective option for CTCL; however, its low cost is offset by its limited effectiveness in advanced stages of CTCL. ECP and interferon appear the next most cost-effective therapies.

Treatment-free interval as a metric of patient experience and a health outcome of value for advanced multiple myeloma: the case for the histone deacetylase inhibitor panobinostat, a next-generation novel agent.

BACKGROUND: Patients with relapsed or relapsed/refractory multiple myeloma (RRMM) face poor treatment options by the time third-line therapy is required, despite advances in overall survival in recent years. Treatment free interval (TFI) and opportunities to maintain quality of life (QoL) have been cited as additional measures of efficacy that can be utilized in personalized treatment decisions. METHODS: The clinical health outcomes data from PANORAMA-1, the pivotal phase-3 trial comparing panobinostat-bortezomib-dexamethasone (PAN-BTZ-DEX) with placebo (PBO)-BTZ-DEX in RRMM patients treated with 1 to 3 prior regimens, retrospectively assessed TFI as a health outcome measure and metric of patient treatment experience relevant to the RRMM population. RESULTS: PAN-BTZ-DEX shows promise for prolonged TFI (mean TFI, 7.49 months; 95% CI, 6.02 to 8.71) compared to PBO-BTZ-DEX (mean TFI, 3.86 months; 95% CI, 3.08 to 4.60) for heavily pre-treated advanced RRMM patients), due to the short duration of therapy and extended progression free-survival. Further, QoL during the TFI was similar to baseline. CONCLUSIONS: PAN-BTZ-DEX provides a treatment regimen with prolonged TFI benefits previously not available for RRMM patients. TFI has not been traditionally measured in clinical trials, but should be assessed in prospective data collection given its value to payers, providers, and patients.

Assessment of objective responses using volumetric evaluation in advanced thymic malignancies and metastatic non-small cell lung cancer.

INTRODUCTION: Measurement of tumor response by standard response criteria is challenging in thymic malignancies, especially when the pleura is involved, as it often is in stage IV disease. In this study, we aimed to determine the effectiveness of volumetric response evaluation criteria in solid tumors (volumetrics) for evaluating response in patients with thymic malignancies treated on a phase II study of belinostat. METHODS: We evaluated the tumor responses of 25 patients with thymic cancer using computed tomography-based RECIST, World Health Organization (WHO), modified RECIST, and volumetrics. As a control, we assessed 37 patients with non-small cell lung cancer (NSCLC) with RECIST and volumetrics. RESULTS: Agreement analyses in 23 patients with thymic cancer at the time of RECIST-determined progressive disease (PD) compared volumetrics with RECIST, modified RECIST, and WHO criteria. Use of volumetrics was associated with 22% discordance compared with RECIST, 15% versus modified RECIST, and 22% versus WHO criteria. Volumetrics revealed PD 72 days earlier than RECIST (p = 0.016). In another cohort of 35 patients with NSCLC, there was 9% discordance between volumetrics and RECIST at the time of PD. Volumetrics demonstrated PD 32 days earlier than RECIST in NSCLC (p = 0.0078). CONCLUSIONS: Our study suggests that volumetrics might improve detection of PD. Prospective evaluation of this technique in a larger series of patients with thymic malignancies will be required.

Treatment of cutaneous T-cell lymphoma/mycosis fungoides.

The cause of mycosis fungoides is unknown and, with the possible exception of very early stage disease, no cure is available. Fortunately, patients with MF have a number of therapeutic options and partial and complete remissions are achievable. Because it is not curable, the burden for patients with this disease involves the need for lifelong therapy and monitoring, and meticulous skin care. Despite its indolent nature in most individuals, the disease has a tremendous psychological impact, not only because of the visible nature of the skin lesions, but also due to the rarity of the disease and its chronicity. Knowledge of this disease, therapeutic options, and expectations of therapy will enhance care of patients afflicted with mycosis fungoides. Ongoing research provides hope that in the future, therapy to induce long-lasting remission, or even cure, will become available. Since the submission of this manuscript, vorinostat (Zolinza), an orally administered histone inhibitor, has been FDA approved for treating skin manifestations in patients with CTCL.