Richard Piekarz

Phase II Multi-Institutional Trial of the Histone Deacetylase Inhibitor Romidepsin As Monotherapy for Patients With Cutaneous T-Cell Lymphoma

PURPOSE Romidepsin (depsipeptide or FK228) is a member of a new class of antineoplastic agents active in T-cell lymphoma, the histone deacetylase inhibitors. On the basis of observed responses in a phase I trial, a phase II trial of romidepsin in patients with T-cell lymphoma was initiated. PATIENTS AND METHODS The initial cohort was limited to patients with cutaneous T-cell lymphoma (CTCL), or subtypes mycosis fungoides or Sézary syndrome, who had received no more than two prior cytotoxic regimens. There were no limits on other types of therapy. Subsequently, the protocol was expanded to enroll patients who had received more than two prior cytotoxic regimens. Results Twenty-seven patients were enrolled onto the first cohort, and a total of 71 patients are included in this analysis. These patients had undergone a median of four prior treatments, and 62 patients (87%) had advanced-stage disease (stage IIB, n = 15; stage III, n= 6; or stage IV, n = 41). Toxicities included nausea, vomiting, fatigue, and transient thrombocytopenia and granulocytopenia. Pharmacokinetics were evaluated with the first administration of romidepsin. Complete responses were observed in four patients, and partial responses were observed in 20 patients for an overall response rate of 34% (95% CI, 23% to 46%). The median duration of response was 13.7 months. CONCLUSION The histone deacetylase inhibitor romidepsin has single-agent clinical activity with significant and durable responses in patients with CTCL.

Phase 2 trial of romidepsin in patients with peripheral T-cell lymphoma

Romidepsin (depsipeptide or FK228) is a histone deacetylase inhibitor, one of a new class of agents active in T-cell lymphoma. A phase 2 trial was conducted in cutaneous (CTCL) and peripheral (PTCL) T-cell lymphoma. Major and durable responses in CTCL supported the approval of romidepsin for CTCL. Forty-seven patients with PTCL of various subtypes including PTCL NOS, angioimmunoblastic, ALK-negative anaplastic large cell lymphoma, and enteropathy-associated T-cell lymphoma were enrolled. All patients had received prior therapy with a median of 3 previous treatments (range 1-11); 18 (38%) had undergone stem-cell transplant. All patients were evaluated for toxicity; 2 patients discovered to be ineligible were excluded from response assessment. Common toxicities were nausea, fatigue, and transient thrombocytopenia and granulocytopenia. Complete responses were observed in 8 and partial responses in 9 of 45 patients, for an overall response rate of 38% (95% confidence interval 24%-53%). The median duration of overall response was 8.9 months (range 2-74). Responses were observed in various subtypes, with 6 responses among the 18 patients with prior stem-cell transplant. The histone deacetylase inhibitor romidepsin has single agent clinical activity associated with durable responses in patients with relapsed PTCL.

Cardiac Studies in Patients Treated with Depsipeptide, FK228, in a Phase II Trial for T-Cell Lymphoma

Purpose: The histone deacetylase inhibitor depsipeptide (FK228) has activity in patients with cutaneous or peripheral T-cell lymphoma. Electrocardiogram abnormalities, thought to be a class effect, were observed in preclinical animal studies and phase I testing and led to the incorporation of intensive cardiac monitoring in an ongoing efficacy trial. Patients and Methods: This report summarizes the cardiac monitoring of 42 patients enrolled and treated on a phase II trial with depsipeptide. Cardiac evaluations included serial electrocardiograms to evaluate T-wave, ST segment, and QT interval effects and serial serum cardiac troponin I levels and left ventricular ejection fraction (LVEF) evaluations to exclude myocardial damage. Results: Cardiac studies from 282 cycles and 736 doses of depsipeptide included 2,051 electrocardiograms and 161 LVEF evaluations. Although T-wave flattening (grade 1) or ST segment depression (grade 2) was observed in more than half of the electrocardiograms obtained posttreatment, these electrocardiogram abnormalities were not associated with elevation of cardiac troponin I or with altered left ventricular function. No significant changes in LVEF were observed, even in 16 patients treated for ≥6 months and regardless of prior anthracycline exposure. Posttreatment electrocardiograms had a mean heart rate–corrected QT interval prolongation of 14.4 milliseconds compared with baseline. Electrolyte replacement has been instituted to mitigate potential untoward effects. Conclusion: The data obtained in this study show that the administration of depsipeptide is not associated with myocardial damage or impaired cardiac function. The potential effect of heart rate–corrected QT interval prolongation remains under study.

A Review of Depsipeptide and Other Histone Deacetylase Inhibitors in Clinical Trials

The histone deacetylase inhibitors (HDIs) are a new class of antineoplastic agents currently being evaluated in clinical trials. While these agents have been studied extensively in the laboratory, only recently has their mechanism of action begun to be elucidated. Several structural classes of compounds have been shown to exert histone deacetylase inhibition, including sodium n-butyrate, suberoylanilide hydroxamic acid, LAQ824, CI-994, MS-275, and depsipeptide. The HDIs have been shown to induce differentiation, to decrease cell proliferation, and to induce cell death. HDIs are thought to exert their anti-neoplastic effects by altering the expression of genes that play a role in the control of cell growth, and transformation. The HDIs have specific and well-defined effects on cancer cells. Preliminary results from clinical trials suggest that these agents are very promising. While there were sporadic case reports of activity using the early generation HDIs, dramatic responses have recently been observed in patients with T-cell lymphomas treated with depsipeptide, one of the newer agents. With the well-defined molecular effects on cancer cells, surrogate markers can be analyzed for evidence of activity and efficacy using either tumor samples or normal tissue. Presented in this review are details from clinical trials with both earlier and newer generations of HDIs. Toxicities specific to this class of agents are outlined and possibilities for rational combination therapies are discussed.

Epigenetic Modifiers: Basic Understanding and Clinical Development

More than 60 years after the first description of differentiation in cell culture and 40 years after the synthesis of 5-azacytidine, epigenetic therapies have been added to the anticancer armamentarium. DNA methyltransferase (DNMT) inhibitors such as 5-aza-2′-deoxycytidine or 5-azacytidine have been approved in myelodysplastic syndrome (MDS) and acute myelogenous leukemia (AML), whereas the histone deacetylase inhibitors (HDIs) including vorinostat, romidepsin, panobinostat, belinostat, and entinostat have been shown to be active in cutaneous and peripheral T-cell lymphoma. Although the range of malignancies in which monotherapy with DNMT inhibitors or HDIs are effective has been limited to date, the possibility remains that a broader spectrum of activity will be identified as combination studies are completed. Meanwhile, basic science has provided a steadily increasing understanding of the complexity of the epigenome, including the histone code and triggers for aberrant methylation, and their contribution to oncogenesis. As our basic understanding of the epigenetics of cancer increases, the number of potential therapeutic targets will also increase, offering more hope in the quest to treat cancer by normalizing the epigenome. This issue of CCR Focus is dedicated to understanding the clinical and translational aspects of epigenetics research.

Clinical Toxicities of Histone Deacetylase Inhibitors

The HDAC inhibitors are a new family of antineoplastic agents. Since the entry of these agents into our therapeutic armamentarium, there has been increasing interest in their use. Although this family comprises chemical compounds from unrelated chemical classes that have different HDAC isoform specificities, they surprisingly have very similar toxicity profiles. In contrast, the observed toxicity profile is somewhat different from that of traditional cytotoxic chemotherapeutic agents and from other epigenetic agents. While some of the side effects may be familiar to the oncologist, others are less commonly seen. As some patients remain on therapy for a prolonged period of time, the long-term sequelae need to be characterized. In addition, since preclinical models suggest promising activity when used in combination with other antineoplastic agents, combination trials are being pursued. It will thus be important to distinguish the relative toxicity attributed to these agents and be alert to the exacerbation of toxicities observed in single agent studies. Notably, few of the agents in this class have completed phase 2 testing. Consequently, more clinical experience is needed to determine the relative frequency of the observed side effects, and to identify and develop approaches to mitigate potential clinical sequelae.

Increased MDR1 Expression in Normal and Malignant Peripheral Blood Mononuclear Cells Obtained from Patients Receiving Depsipeptide (FR901228, FK228, NSC630176)

The increased expression of markers associated with a differentiated phenotype, such as P-glycoprotein (Pgp), follows treatment with histone deacetylase inhibitors. Because depsipeptide (FR901228, FK228, NSC630176) is a substrate for Pgp, up-regulation of the gene that encodes it, MDR1, would mean that depsipeptide induces its own mechanism of resistance. To examine the effect of depsipeptide on expression of ATP-binding cassette transporters associated with multidrug resistance, the kidney cancer cell lines 108, 121, 127, and 143 were treated with depsipeptide and evaluated by quantitative reverse transcription-PCR. Increased levels of MDR1 (1.3- to 6.3-fold) and ABCG2 (3.2- to 11.1-fold) but not MRP1 (0.9- to 1.3-fold) were observed. The induced Pgp transported the fluorescent substrates rhodamine 123, bisantrene, calcein-AM, BODIPY-vinblastine, and BODIPY-paclitaxel. In normal peripheral blood mononuclear cells (PBMC) and circulating tumor cells obtained from patients receiving depsipeptide, increased levels of histone H3 acetylation were found. We next examined MDR1 levels in normal and malignant PBMCs obtained from 15 patients enrolled in clinical trials with depsipeptide and detected up to a 6-fold increase in normal PBMCs and up to an 8-fold increase in circulating tumor cells after depsipeptide administration. In one patient with Sézary syndrome, increased MDR1 gene expression was accompanied by increased cell surface Pgp expression in circulating Sézary cells as determined by measurement of MRK-16 staining by flow cytometry. These studies suggest that depsipeptide induces its own mechanism of resistance and thus provide a basis for clinical trials evaluating depsipeptide in combination with a Pgp inhibitor.

Laboratory correlates for a phase II trial of romidepsin in cutaneous and peripheral T-cell lymphoma.

Romidepsin has shown promise in the treatment of T‐cell lymphomas, and so we evaluated molecular endpoints gathered from 61 patients enrolled on a phase II trial of romidepsin in cutaneous and peripheral T‐cell lymphoma at the National Institutes of Health. The endpoints included histone H3 acetylation and ABCB1 gene expression in peripheral blood mononuclear cells (PBMCs); ABCB1 gene expression in tumour biopsy samples; and blood fetal haemoglobin levels (HbF), all of which were increased following romidepsin treatment. The fold increase in histone acetylation in PBMCs at 24 h was weakly to moderately well correlated with the pharmacokinetic parameters Cmax and area under the curve (AUC)last (ρ = 0·37, P = 0·03 and ρ = 0·36, P = 0·03 respectively) and inversely associated with clearance (ρ = −0·44; P = 0·03). Histone acetylation in PBMCs at 24 h was associated with response (P = 0·026) as was the increase in fetal haemoglobin (P = 0·014); this latter association may be due to the longer on‐study duration for patients with disease response. Together, these results suggest that pharmacokinetics may be an important determinant of response to histone deacetylase inhibitors (HDIs) – the association with histone acetylation in PBMCs at 24 h is consistent with a hypothesis that potent HDIs are needed for a critical threshold of drug exposure and durable activity.

Histone deacetylase inhibitors and demethylating agents : Clinical development of histone deacetylase inhibitors for cancer therapy

The histone deacetylase inhibitors are a new class of agents that are currently in various stages of clinical development. Clinical trials have demonstrated activity, urging further investigation. At the same time, it has been discovered that these agents have their own challenges. In this review, we discuss clinical data gathered to date, combination therapies designed to increase efficacy, and toxicities attributed to this new class of agents.

Population Pharmacokinetics of Romidepsin in Patients with Cutaneous T-Cell Lymphoma and Relapsed Peripheral T-Cell Lymphoma

Purpose: Romidepsin is a potent histone deacetylase inhibitor under clinical development. The objective of this study was to evaluate the effect of demographic, clinical, and pharmacogenetic covariates on the pharmacokinetics of romidepsin in patients with T-cell lymphoma. Experimental Design: Pharmacokinetic assessment was done in 98 patients enrolled in a phase II study who received 14 or 18 mg/m2 of romidepsin as a 4-hour infusion on day 1 during their first treatment cycle. Population modeling was done using a nonlinear mixed effects modeling approach to explore the effects of polymorphic variations in CYP3A4, CYP3A5, SLCO1B3, and ABCB1, all of which encode genes thought to be involved in romidepsin disposition. Results: A two-compartment model with linear kinetics adequately described the romidepsin disposition. Population clearance was 15.9 L/h with between-patient variability of 37%. ABCB1 2677G>T/A variant alleles tended toward a reduced clearance and lower volume of tissue distribution, but this was not supported by a statistical significance. Genetic variations in CYP3A4/5 and SCLO1B3 had no effect on the systemic exposure. Conclusion: The population pharmacokinetic analysis indicates moderate interindividual variability in romidepsin pharmacokinetics and no clinically relevant covariates associated with the unexplained pharmacokinetic variability of romidepsin in this population.