First-in-human, pharmacokinetic and pharmacodynamic phase I study of Resminostat, an oral histone deacetylase inhibitor, in patients with advanced solid tumors

PURPOSE

This first-in-human dose-escalating trial investigated the safety, tolerability, maximum tolerated dose (MTD), dose-limiting toxicities (DLT), pharmacokinetics, and pharmacodynamics of the novel histone deacetylase (HDAC) inhibitor resminostat in patients with advanced solid tumors.

EXPERIMENTAL DESIGN

Resminostat was administered orally once-daily on days 1 to 5 every 14 days at 5 dose levels between 100 and 800 mg. Safety, pharmacokinetics, pharmacodynamics including histone acetylation and HDAC enzyme activity, and antitumor efficacy were assessed.

RESULTS

Nineteen patients (median age 58 years, range 39-70) were treated. At 800 mg, 1 patient experienced grade 3 nausea and vomiting, grade 2 liver enzyme elevation, and grade 1 hypokalemia and thrombocytopenia; these were declared as a combined DLT. No other DLT was observed. Although an MTD was not reached and patients were safely dosed up to 800 mg, 3 of 7 patients treated with 800 mg underwent dose reductions after the DLT-defining period due to cumulative gastrointestinal toxicities and fatigue. All toxicities resolved following drug cessation. No grade 4 treatment-related adverse event was observed. The pharmacokinetic profile was dose-proportional with low inter-patient variability. Pharmacodynamic inhibition of HDAC enzyme was dose-dependent and reached 100% at doses ≥400 mg. Eleven heavily pretreated patients had stable disease and 1 patient with metastatic thymoma had a 27% reduction in target lesion dimensions.

CONCLUSIONS

Resminostat was safely administered with a dose-proportional pharmacokinetic profile, optimal on-target pharmacodynamic activity at dose levels ≥400 mg and signs of antitumor efficacy. The recommended phase II dose is 600 mg once-daily on days 1 to 5 every 14 days.

Quantification of periciliary fluid height in human airway biopsies is feasible, but not suitable as a biomarker

The "low volume hypothesis," stating that imbalanced ion movement across the cystic fibrosis (CF) airway epithelium leads to a reduction in periciliary fluid (PCL) and consequently impaired mucociliary clearance, has been the prevailing theory explaining CF pathophysiology, and has been supported by animal models and ex vivo cell culture systems. However, studies in freshly obtained human tissue have not yet been performed. Methods to quantify PCL height in freshly obtained airway biopsies may be useful to assess efficacy of new treatments aimed at restoring PCL height. Here, we established methods to quantify PCL height in freshly obtained CF and non-CF human lower airway biopsies. More than 90% of biopsies contained ciliated epithelium, and PCL height measurements were feasible in approximately 50% of these. Although the mean PCL height was reduced in CF tissue (non-CF, 5.60 ± 0.28 μm; CF, 4.52 ± 0.47 μm), this did not reach statistical significance (P = 0.06). To strengthen the data, we performed similar studies in wild-type and CF knockout mice, and confirmed the results (non-CF, 4.70 ± 0.13; CF, 4.10 ± 0.09 μm; P < 0.05). PCL height measurements in freshly obtained human airway biopsies are feasible, and PCL height appears reduced in subjects with CF, thereby further supporting the "low volume hypothesis." However, power calculations indicate that this assay can only be considered as a biomarker in large, late-phase clinical trials, because sample sizes required to achieve sufficient power are comparatively large.

Preliminary activity in adrenocortical tumor (ACC) in phase I dose escalation study of intermittent oral dosing of OSI-906, a small-molecule insulin-like growth factor-1 receptor (IGF-1R) tyrosine kinase inhibitor in patients with advanced solid tumors

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Background: IGF-1R is overexpressed in various malignancies, and implicated in proliferation, survival, and metastasis. IGF-1R blockade increases apoptosis and reduces tumor growth in preclinical models. OSI-906 is an oral small molecule tyrosine kinase IGR-1R inhibitor. Methods: Patients (pt) with advanced solid tumours were enrolled to determine safety, tolerability, maximum tolerated dose, pharmacokinetics (PK), pharmacodynamics (PD) and preliminary anti-tumor activity. Results: 26 pt have been treated (14M:12F, median age 61 yrs) at 10, 20, 40, 80, 150, 300, and 450 mg on days (d) 1–3 q14 d. No dose-limiting toxicities have been observed to date. Drug-related toxicities include grade 1 fatigue, nausea, rash, diarrhea, tachycardia, proteinuria, pruritis and peripheral oedema. Linear PK was observed, with median terminal t1/2 3.5 hr; AUC0-∞ 25.8 μg.hr/mL; Cmax 3.20 μg/ml at 450mg. Plasma OSI-906 concentrations above the estimated efficacious concentration (1 μM) were attained at doses > 40mg. Glucose did not increase with rising OSI-906 concentration, but plasma insulin levels showed an upward trend, indicating potential PD effects. PD data on IGFR phosphorylation were analyzed. In total, 11 pt were treated for > 12 weeks (w). Of 3 pt with ACC, 1 pt had a partial response (43% reduction in primary and multiple lung metastases) and remains on treatment after 16 w, 1 pt was treated for 32 w, and 1 pt progressed after 4 w at 40mg. In addition, 1 pt with heavily pretreated NSCLC was treated for 43 w and 1 pt with progressive myxoid chondrosarcoma remains on treatment after 38 w. Conclusions: OSI 906 had minimal toxicity, dose proportional PK at dose levels up to 450mg tested d 1–3 q14 d, with preliminary antitumor activity seen, particularly in ACC. Dose escalation with 5 and 7 d schedules q14 d continues.

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