Abstract
ART‐001 is an orally available selective PI3Kα inhibitor currently being developed for the treatment of slow‐flow vascular malformations (SFVMs). ART‐001 used to be developed for advanced solid tumors, but was suspended largely due to significant pharmacokinetic (PK) variability in its phase I studies. This phase I, randomized, double‐blinded, placebo‐controlled study evaluated safety, tolerability and PK of ART‐001 with a newly developed dry syrup formulation, which was designed to optimize PK properties of ART‐001 and to be compliant with the pediatric population. Single and multiple doses of ART‐001 were administered to healthy male adults. ART‐001 was rapidly absorbed after the single and repeated doses, and the exposure of ART‐001 increased with increased dose. The dry syrup formulation substantially improved the intersubject PK variability. Food decreased area under the concentration‐time curve (AUC) and maximum plasma concentration by 12% and 36%, respectively. The plasma concentration had reached a steady‐state on day 5 of the repeated doses of 100 mg and AUC accumulation ratio was 1.9. There were no deaths or serious adverse events. The most frequent adverse event was hyperglycemia. All cases of hyperglycemia were mild to moderate and transient, and required no medical interventions. Serum creatinine increase was observed in 300 mg once daily dosing group leading to dose discontinuation on day 5. In conclusion, it was demonstrated that the single doses and repeated doses of the ART‐001 dry syrup formulation, at up to 400 and 100 mg, respectively, were safe and tolerated with favorable PK profile, supporting further clinical development for the treatment of SFVMs.
Study Highlights.
WHAT IS THE CURRENT KNOWLEDGE ON THE TOPIC?
ART‐001 (serabelisib) is an orally available selective PI3Kα inhibitor which used to be developed for advanced solid tumors. Previous phase I studies demonstrated that ART‐001 in capsule and tablet formulation has significant pharmacokinetic (PK) variability probably due to its pH‐dependent solubility profile.
WHAT QUESTION DID THIS STUDY ADDRESS?
This phase I study evaluated safety, tolerability, and PKs of single and multiple doses of ART‐001 with a newly developed dry syrup formulation, which was designed to optimize PK properties of ART‐001 and to be compliant with the pediatric population.
WHAT DOES THIS STUDY ADD TO OUR KNOWLEDGE?
This study describes the safety and tolerability and improved PK profiles of ART‐001 with new dry syrup formulation in healthy male adults.
HOW MIGHT THIS CHANGE CLINICAL PHARMACOLOGY OR TRANSLATIONAL SCIENCE?
The study results support the further clinical development of ART‐001, inform on dosing, and safety and tolerability of ART‐001 for clinical trials in patients with slow‐flow vascular malformations.
INTRODUCTION
Vascular anomalies are abnormalities or disorders of the vascular system. Slow‐flow vascular malformations (SFVMs) is one of the classifications in vascular anomalies, including venous malformations and lymphatic malformations, as well as combined vascular malformations, such as Klippel‐Trenaunay syndrome. SFVMs often present at birth and, in some cases, the lesion continuously grows throughout the patient's life. SFVMs often cause disfigurements, pain, chronic anemia, coagulation abnormalities, and functional impairment, which negatively impact patients' quality of life in both pediatric and adult patients. Because conventional treatments, such as surgery and sclerotherapy, are rarely curative, there is a high unmet medical need for new therapeutic options/modalities.
Recent studies revealed that phosphatidylinositol 3‐kinase alpha (PI3Kα)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) pathway plays an important role in the pathogenesis of SFVMs. 1 , 2 Multiple studies demonstrated that most of the patients with SFVMs have somatic gain‐of‐function mutations in genes encoding PI3Kα and its upstream or downstream kinases. 3 , 4 , 5 , 6 , 7 In addition, there is accumulating clinical evidence suggesting the pharmacological inhibition of PI3K/AKT/mTOR pathway (i.e., mTOR inhibitor sirolimus and PI3Kα inhibitor alpelisib) would be a promising approach for the treatment of SFVMs. 8 , 9 , 10 , 11 , 12
ART‐001 (serabelisib, also known as TAK‐117) is a novel, orally available, selective PI3Kα inhibitor, originally developed for advanced solid tumors, but is now being developed for the treatment of SFVMs in both the pediatric and adult populations. ART‐001 showed large pharmacokinetic (PK) variability in previous clinical studies. For example, in the phase I clinical study with the capsule formulation in patients with solid tumors, percent coefficient variation (%CV) for the area under the concentration‐time curve (AUC) ranged from zero to infinity (AUCinf) was greater than 100%. 13 It has been considered that the large PK variability of ART‐001 is caused by its unique pH‐dependent aqueous solubility profile, where ART‐001 is extremely soluble at acidic conditions, but not soluble at neutral to basic conditions. Due to this pH‐dependent solubility profile, the absorption of ART‐001 could be largely affected by a gastric pH condition. Indeed, a phase I PK study in healthy adults demonstrated that concomitant administration of ART‐001 in tablet formulation with the gastric pH‐modifying agent lansoprazole significantly reduced the oral bioavailability of ART‐001. 14
To optimize PK properties of ART‐001 and to be compliant with the pediatric population, a novel dry syrup formulation that can be administered to the pediatric and adult population in the planned phase II study and beyond is being developed. Dry syrup is a powder formulation commonly used in Japan, India, and other Asian countries to administer oral drugs to pediatric patients. Dry syrup is suspended or dissolved in a small amount of water typically on an outpatient basis just prior to administration. In the current development strategy, we first characterized the newly developed dry syrup formulation in preclinical settings and then determined the PK, safety, and tolerability of ART‐001 after single and repeated doses in adult healthy male subjects in the present phase I study (JapicCTI‐205373).
METHODS
ART‐001 dry syrup formulations
ART‐001 dry syrup was formulated by granulizing ART‐001 with various additives, including multiple acids aiming to improve the solubility in water and maintain its soluble form even in higher pH than general gastric condition. Prototype A and B (data not disclosed) were used for the preclinical characterization. Dry syrup for the phase I study was prepared by adding sweeteners and flavor additives to the prototype B formulation.
Characterization of ART‐001 dry syrup formulation
Dissolution test
Each prototype formulation was reconstituted to a suspension with water (ART‐001300 mg/100 mL) and applied to the paddle method dissolution test (pH 4.0 testing solution 800 mL, 50 rpm). ART‐001 was determined by high‐performance liquid chromatography and calculated dissolution rate over time.
In vivo PK study in dogs
Single dose study was conducted to characterize the PK profile of each prototype formulation in dogs. Six adult male Beagle dogs were repeatedly used in the study. Their gastric pH was adjusted to 2 or 8–9 prior to the dosing by pretreatment of pentagastrin or famotidine, respectively. ART‐001 in 0.5% methylcellulose (MC) suspension was also tested in dogs with pentagastrin or famotidine pretreatment as control.
Phase I clinical study in healthy male subjects
The study was performed at the Department of Clinical Pharmacology, Nishi Kumamoto Hospital (Kumamoto, Japan), in accordance with Good Clinical Practice, and the ethical principles of the Declaration of Helsinki. All subjects provided written informed consent before beginning any study procedures. The protocols, amendments, and subject‐informed consents were approved by the Hakata Clinic Institutional Review Board prior to initiation. The study was registered under JapicCTI‐205373.
Subjects
Healthy Japanese men aged 20–45 years, with body mass index (BMI) of 18.5–30.0 kg/m2 and body weight of 40 kg or more were eligible to participate. Key exclusion criteria include current or history of kidney or liver diseases which may affect to the PKs of ART‐001, especially in drug metabolism and excretion. Each study subject was screened and retested prior to dosing for laboratory testing including aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, and creatinine to exclude active liver and/or kidney diseases.
Study design
The study was a two‐part (parts I and II) randomized, double‐blind, placebo‐controlled study to evaluate safety, tolerability, and PK of ART‐001 with dry syrup formulation in healthy male adults. Part I evaluated ART‐001 in a five‐step single rising dose (SRD) and part II in a two‐step multiple rising dose (MRD). Dose escalation was based on a review of the available safety, tolerability, and PK data from the preceding step(s). ART‐001 dry syrup was reconstituted to a suspension with 100 mL water just before each dosing.
Part I: SRD study
Part I had a hybrid study design consisting of a placebo‐controlled study to evaluate safety, tolerability, and PK of ART‐001 in SRD (steps 1–5) and an open‐label study to evaluate the food effect (step 6). Part I was conducted by the alternating panel with groups A and B (8 subjects per group). In steps 1–5, eight subjects were randomized in a 6:2 ratio to receive either ART‐001 at dose of 50–400 mg or placebo under the fasted condition. In step 6, eight subjects received a single oral dose of ART‐001 at 100 mg under the fed condition (high‐fat meal). There was a washout period of at least 7 days between doses of the study drug.
Part II: MRD study
Part II MRD study evaluated safety, tolerability, and PK of ART‐001. A total of 16 subjects (8 subjects per group) were enrolled in groups C and D. Eight subjects in each group were randomized in a 6:2 ratio to receive either ART‐001 (100 mg or 300 mg) or placebo post meal once daily (q.d.) for 7 days.
Pharmacokinetics
Blood samples were collected at predose and subsequent prespecified times postdose in both the SRD and MRD studies. Plasma samples were analyzed for ART‐001 using a validated liquid chromatography tandem‐mass spectrometry method at Sekisui Medical. The lower limit of quantification was 10 ng/mL. The PK parameters, such as maximum plasma concentration (C max) and AUC, were analyzed by standard noncompartmental methods of analysis using R (version 4.0.2). Dose proportionality in C max and AUC were assessed by a log transformed power model. Food effect was assessed by calculating geometric mean ratio of C max and AUC with 90% confidence interval between 100 mg dosing groups under fasted and fed conditions.
Safety
Safety was assessed at regular intervals throughout all studies and included monitoring of adverse events (AEs), electrocardiograms, vital signs, clinical laboratory tests, and physical examinations. All AEs were graded mild, moderate, or severe in intensity by the investigator. Hyperglycemia was defined as post‐meal plasma glucose increase above 160 mg/dL or fasted plasma glucose at two consecutive timepoints increase above 110 mg/dL. Blood creatinine increase was defined as greater than or equal to 0.3 mg/dL increase in serum creatinine. The frequencies of AEs were summarized using the Medical Dictionary for Regulatory Activities (version 23.1) preferred term.
RESULTS
Characterization of ART‐001 dry syrup formulation
ART‐001 dry syrup formulation is a white powder‐like microgranules (Figure 1a). Both prototypes A and B were completely dissolved in water at least up to 5 mg/mL concentration (data not shown). Prototype A suspension showed reprecipitation of ART‐001 quickly after adding to test solution whereas prototype B suspension retained ART‐001 solved in dissolution test (Figure 1b).
FIGURE 1.
Characterization of ART‐001 dry syrup formulation. (a) Appearance of prototype B. (b) Dissolution test with paddle method. (c) In vivo PK study in dogs. Data are expressed as mean ± SD. MC, methylcellulose; PK, pharmacokinetic.
As shown in Figure 1c, ART‐001 in 0.5% MC suspension was well‐absorbed in dogs pretreated with pentagastrin, whereas there was a least absorption in dogs pretreated with famotidine. ART‐001 exhibited slightly better absorption with prototype A formulation than 0.5% MC suspension. ART‐001 absorption with prototype B formulation in dogs pretreated with famotidine was comparable with the 0.5% MC suspension in dogs pretreated with pentagastrin.
Phase I clinical study in healthy male subjects
Subjects
A total of 45 subjects participated the study. As shown in Figure 2, eight subjects were initially enrolled in each group A and B in part I, followed by five subject replacements after step 1 (n = 1) and step 4 (n = 2) because of consent withdrawal and after step 3 (n = 2) because of AEs (drug‐unrelated). Therefore, a total of 21 subjects received the study drug in part I.
FIGURE 2.
Study design and flow chart. AEs, adverse events.
In part II, eight subjects were enrolled in each group C and D. In group C, the initial eight subjects were replaced due to the important protocol deviation which was dose calculation error. As the initial eight subjects received placebo or ART‐001 of 20 mg (which was only 20% of the planned dose) on day 1, the dosing was discontinued on the day, and they were excluded from the safety and PK population. In group D, six subjects were withdrawn from the study because of AEs and two subjects were withdrawn because of the investigator's decision on day 5.
Baseline characteristics are summarized in Table 1. There was no noteworthy difference in age, height, weight, and BMI among total, part I, and part II. No subjects had complications and medical history of concern.
TABLE 1.
Subject baseline characteristics.
| Total a n = 45 | Part I n = 21 | Part II n = 16 | |
|---|---|---|---|
| Age, years | |||
| Median | 22 | 22 | 21 |
| Minimum, maximum | 20.0, 44.0 | 20.0, 37.0 | 20.0, 39.0 |
| Height, cm | |||
| Median | 172.8 | 171.4 | 174.3 |
| Minimum, maximum | 161.1, 186.8 | 163.9, 185.8 | 162.4, 185.1 |
| Weight, kg | |||
| Median | 67.3 | 67.1 | 66.6 |
| Minimum, maximum | 53.0, 86.6 | 56.9, 80.6 | 53.0, 86.6 |
| BMI, kg/m2 b | |||
| Median | 22.8 | 22.8 | 22.8 |
| Minimum, maximum | 18.5, 28.0 | 18.5, 28.0 | 19.7, 25.9 |
Total includes eight subjects who were excluded from group C in part II due to the protocol deviation.
Body mass index (BMI) is calculated by the following formula: weight (kg)/(height [m])2.
Pharmacokinetics
Part I: SRD study
The plasma concentration versus time profile of ART‐001 following single oral administration is shown in Figure 3a and PK parameters are presented in Table 2. ART‐001 was rapidly absorbed following administration with median time to reach maximum observed concentration (T max) of 1.0–1.5 h up to 300 mg and 4 h at 400 mg. After the peak, plasma ART‐001 concentration declined with the mean terminal half‐life (t 1/2) ranged from 7.0 to 14.4 h across doses and tended to be prolonged at higher doses. Apparent total body clearance (CL/F) decreased with increased dose. C max and AUC increased with increasing dose. Dose proportionality analysis by power model regression for C max and AUC demonstrated that the slope (95% confidence interval [CI]) was 1.02 (0.95, 1.09) and 1.37 (1.28, 1.46), respectively (Figure 3b, Table 2). The 95% CI for C max included 1, indicating that C max showed dose‐linearity in this study. The intersubject variability for C max and AUCinf ranged from 3% to 22% and from 21% to 34%, respectively.
FIGURE 3.
Plasma‐concentration (conc.) time profile for ART‐001 in healthy adult males. (a) Single rising dose. (b) Dose‐proportionality analysis with power model. (c) Food effect. (d) Multiple rising doses. Data are expressed as mean ± SD.
TABLE 2.
PK results for ART‐001 following single and multiple rising oral doses in healthy male adults.
| Part I: SRD study | 50 mg n = 6 | 100 mg n = 6 | 100 mg n = 8 | 200 mg n = 6 | 300 mg n = 6 | 400 mg n = 6 |
|---|---|---|---|---|---|---|
| C max, ng/mL | 1032.5 (13) | 2560.0 (22) | 1625.0 (15) | 4913.3 (3) | 7523.3 (9) | 8281.7 (13) |
| AUClast, ng･h/mL | 10,359.8 (33) | 29,673.0 (26) | 26,123.9 (25) | 63,916.3 (33) | 123,115.0 (15) | 161,095.2 (26) |
| AUC0‐inf, ng･h/mL | 10,570.5 (33) | 30,628.5 (27) | 27,029.0 (26) | 66,702.0 (34) | 133,905.5 (21) | 182,921.2 (33) |
| T max, h a | 1.0 (1.0, 1.0) | 1.0 (1.0, 1.0) | 4.0 (1.0, 4.0) | 1.5 (1.0, 2.0) | 1.5 (1.0, 4.0) | 4.0 (1.0, 4.0) |
| t 1/2, h b | 7.0 (4.2, 9.2) | 9.0 (6.5, 10.3) | 9.1 (6.6, 11.3) | 9.2 (3.8, 11.9) | 12.3 (8.8, 17.3) | 14.4 (10.1, 20.5) |
| Vd/F, mL | 49,599.1 (17) | 43,838.8 (18) | 49,686.8 (13) | 40,059.2 (9) | 39,584.2 (12) | 46,636.5 (12) |
| CLtot/F, mL/h | 5362.1 (46) | 3523.7 (34) | 3963.8 (30) | 3530.0 (55) | 2312.9 (19) | 2401.7 (34) |
| K el, 1/h | 0.106 (31) | 0.079 (19) | 0.079 (22) | 0.088 (55) | 0.059 (25) | 0.050 (23) |
| Part II: MRD study | 100 mg n = 6 | 300 mg n = 6 |
|---|---|---|
| C max 1, ng/mL | 1318.3 (15) | 4498.3 (16) |
| C max ss, ng/mL | 2128.3 (19) | NA |
| AUCl(1,τ=24), ng·h/mL | 16,169.6 (26) | 76,213.8 (25) |
| AUCl(ss,τ=24), ng·h/mL | 30,233.0 (28) | NA |
| Accumulation ratio in AUC a | 1.9 | NA |
| Accumulation ratio in trough concentration b | 2.3 | 2.0 |
| T max,1, h c | 3.0 (1.0, 4.0) | 4.0 (4.0, 6.0) |
| T max,ss, h c | 3.0 (2.0, 4.0) | NA |
| t 1/2,ss, h d | 10.4 (6.7, 12.4) | NA |
| K el,ss, 1/h | 0.070 (26) | NA |
| Dose proportionality by power model regression | ||
|---|---|---|
| Parameter | Slope (95% CI) | Intercept (95% CI) |
| C max | 1.02 (0.95–1.10) | 3.03 (2.64–3.42) |
| AUCinf | 1.37 (1.28–1.46) | 3.87 (3.39–4.35) |
| Food effect | ||||
|---|---|---|---|---|
| Parameter | Geometric mean (fed) | Geometric mean (fasted) | Geometric mean ratio | 90% CI |
| C max | 1608.2 | 2501.8 | 0.643 | 0.532–0.776 |
| AUCinf | 26,146.2 | 29,569 | 0.884 | 0.668–1.174 |
Note: Data are mean (coefficient of variability [CV%]), unless otherwise noted.
Abbreviations: AUC, area under the concentration‐time curve; CI, confidence interval; CLtot/F, total apparent clearance; C max, maximum plasma concentration; MRD, multiple rising dose; NA, not applicable; PK, pharmacokinetic; SRD, single rising dose; t ½, terminal half‐life; T max, time to maximum concentration; Vd/F, apparent volume of distribution.
Ratio of AUC on day 1 and day 7.
Ratio of trough concentration after dosing on day 1 and day 4.
Median (minimum, maximum).
Mean (minimum, maximum).
The food effect was assessed at the dose of 100 mg (Figure 3c, Table 2). The median T max for the fasted and fed state were 1 and 4 h, respectively. The geometric mean ratios (90% CI) of C max and AUCinf were 0.643 (0.532, 0.776) and 0.884 (0.668, 1.174), respectively.
Part II: MRD study
Similar to the single dose PK profile in part I, ART‐001 was rapidly absorbed following repeated doses of ART‐001 at 100 and 300 mg q.d. with the median T max of 3 and 4 h, respectively (Figure 3d, Table 2). In the 100 mg q.d. group, the median T max on day 7 was comparable to that on day 1. Both C max and AUC increased with repeated doses and appeared to reach a steady‐state on day 5 based on the changes over time in trough concentration levels. The accumulation ratio based on AUC was 1.9‐fold. Intersubject PK variability on day 1 and day 7 for C max and AUC were 15% and 19%, and 26% and 32%, respectively.
In the 300 mg q.d. group, sufficient PK information at the steady‐state following the repeated doses is not available because of premature discontinuation on day 5. The plasma trough concentration of ART‐001 continuously increased until day 5 and the steady‐state was not determined. The ratio of trough concentrations after day 1 and day 4 dosing was 2.0.
Safety
Part I: SRD study
The single ART‐001 doses at 50–400 mg were safe and well‐tolerated. The AEs that occurred across part I were nausea, pharyngitis, headache, hyperglycemia, blood insulin increased, and blood creatine phosphokinase (CPK) increased (Table 3). All AEs were mild in severity. Two subjects were withdrawn from the study because of AEs (pharyngitis and blood CPK increased), however, their AEs were not related to the drug.
TABLE 3.
List of adverse events for ART‐001 following single and multiple rising oral doses in healthy male adults.
| Part 1: SRD study | Placebo n = 10 | 50 mg n = 6 | 100 mg n = 6 | 100 mg fed n = 8 | 200 mg n = 6 | 300 mg n = 6 | 400 mg n = 6 |
|---|---|---|---|---|---|---|---|
| Any AEs, n (%) | 2 (20) | 3 (50) | 1 (16.7) | 0 (0) | 2 (33.3) | 4 (66.7) | 6 (100) |
| Nausea | 1 (16.7) | ||||||
| Pharyngitis | 1 (16.7) | 1 (16.7) | |||||
| Headache | 1 (16.7) | ||||||
| Hyperglycemia | 2 (20) | 3 (50) | 6 (100) | 4 (66.7) | 5 (83.3) | 6 (100) | |
| Blood insulin increased | 1 (16.7) | ||||||
| Blood creatine phosphokinase increased | 1 (16.7) |
| Part 1: MRD study | Placebo n = 4 a | 100 mg n = 6 | 300 mg n = 6 b |
|---|---|---|---|
| Any AEs, n (%) | 1 (25) | 3 (50) | 6 (100) |
| Nausea | 4 (66.7) | ||
| Hyperglycemia | 2 (33.3) | 4 (66.7) | |
| Blood insulin increased | 6 (100) | ||
| Blood creatinine increased | 6 (100) | ||
| Blood creatine phosphokinase increased | 1 (25) | 1 (16.7) | |
| Glucose urine | 3 (50) |
Abbreviations: AEs, adverse events; MRD, multiple rising dose; SRD, single rising dose.
Include 2 subjects in 300 mg/day group who were terminated dosing on day 5.
Terminated the dosing on day 5.
The most common drug‐related AE was hyperglycemia. The incidence rate of hyperglycemia increased in a dose‐dependent manner. All these hyperglycemia cases were judged mild because of rapid recovery without prolongation, no clinical signs due to blood glucose increase, and no need for medical treatment. As other drug‐related AEs, blood insulin increased in one of six subjects (16.7%), nausea in one of six (16.7%), and headache in one of six subjects (16.7%) occurred after the dose of 400 mg. All these AEs resolved subsequently.
Figure 4a shows the changes in the mean blood glucose levels following single administration of ART‐001 under the fasted condition. The blood glucose levels were increased in a dose‐dependent manner, then back to the baseline levels subsequently. The blood glucose levels remarkably increased at 6 h after administration in all dosing groups, even in the placebo group, because all subjects had lunch just after the blood sampling at 4 h postdose. This remarkable increase of blood glucose levels was ameliorated in the subjects who had breakfast with the mean blood glucose level of 140.8 ± 8.0 mg/dL, which was comparable to that in the placebo group (Figure 4b).
FIGURE 4.
Blood glucose and serum creatinine concentrations following single rising doses of ART‐001 in healthy adult males. (a) Blood glucose concentrations after single dosing under fasted condition. Data are expressed as mean ± SD. (b) Comparison of blood glucose concentrations after single dosing between fasted and fed conditions. Data are expressed as mean ± SD. Statistical analysis by Tukey test, different alphabet indicates statistically significant difference p < 0.005. (c) Maximum fold change from baseline during first 4 h following single doses. X represents the geometric mean. Statistical analysis by Dunnett test, ns, * and ** indicate no significant difference, significant difference p < 0.005 and p < 0.001, respectively. (d) Individual blood glucose concentrations in the 300 mg q.d. group. (e) Individual serum creatinine concentrations in the 300 mg q.d. group.
Figure 4c shows the maximal fold change from baseline in the fasting blood glucose levels during first 4 h after dosing, indicating that ART‐001 increased fasting blood glucose in a dose‐dependent manner starting from around the dose of 100 mg (p < 0.05, Dunnett test).
Part II: MRD study
The repeated dose of ART‐001 at 100 mg q.d. was safe and well‐tolerated. Mild hyperglycemia (n = 2) and mild blood CPK increased (n = 1) occurred but these AEs were not drug‐related. In contrast, the repeated dose at 300 mg q.d. was discontinued on day 5 because of AEs. The following drug‐related AEs occurred in 300 mg q.d. group; nausea in four of six subjects (66.7%), hyperglycemia in three of six subjects (50%), blood insulin increased in six of six subjects (100%), blood creatinine increased in six of six subjects (100%), and glucose urine in three of six subjects (50%). Individual blood glucose changes in the 300 mg q.d. group are shown in Figure 4d. Two of four subjects who had hyperglycemia showed fasted blood glucose increased above 140 mg/dL, which defined moderate hyperglycemia. Individual serum creatinine changes in the 300 mg q.d. group are also shown in Figure 4e. Two of six subjects who had blood creatinine increases showed increasing serum creatinine greater than or equal to 1.5‐fold from baseline and also above the upper limit of normal 1.04 mg/dL. They were defined as moderate in intensity. All other AEs were mild except moderate nausea in one subject. All AEs were resolved after completion or discontinuation of the dosing. The subjects who showed blood creatinine increases had additional testing for renal function (serum cystatin C, urine NGAL, and urine β2 microglobulin). There was no change in serum cystatin C in all subjects. Whereas urine β2 microglobulin levels slightly exceeded the reference value in some subjects, urine NGAL levels were within the reference value in all subjects tested.
DISCUSSION
Previous phase I studies in patients with cancer and healthy adults revealed that ART‐001 in capsule or tablet formulation had the marked intersubject PK variabilities, 13 , 14 and it was considered due to the pH dependent aqueous solubility profile of ART‐001. 14 To optimize PK properties of ART‐001 and to be compliant with the pediatric population with SFVMs, we developed a novel dry syrup formulation and tested its safety and PK profile in healthy male adults.
Characterization of ART‐001 dry syrup formulation
ART‐001 dry syrup is a white powder‐like microgranule formulation which can be completely dissolved in water at least up to 5 mg/mL concentration. This reconstituted suspension kept ART‐001 being solved in pH = 4 solution in a dissolution test. ART‐001 in 0.5% MC suspension was well‐absorbed in dogs pretreated with pentagastrin (gastric pH = 2) whereas there was a least absorption of ART‐001 in dogs pretreated with famotidine (gastric pH = 8–9), which well replicated the finding in a previous phase I PK study concomitant with lansoprazole. 14 ART‐001 dry syrup formulation because of its high solubility profile in higher pH conditions, showed good absorption in dogs pretreated with famotidine. These data suggest that ART‐001 dry syrup formulation would minimize PK variability by improving solubility of ART‐001 at wide range of gastric pH.
Phase I clinical study in healthy male subjects
Pharmacokinetics
ART‐001 was rapidly absorbed after the single and repeated doses, and the exposure of ART‐001 increased with increased dose. Although this study did not aim to directly compare the PK profile of dry syrup to that of previous capsule or tablet formulation, %CV for C max and AUClast in part I ranged from 3.4% to 34.3%, suggesting that use of the dry syrup formulation would substantially improve the intersubject PK variability of ART‐001 that had been observed in the previous clinical studies. 13 , 14 In the previous phase I single dose PK study in healthy subjects, ART‐001 in capsule formulation showed high PK variability with %CV for C max and AUCinf of 71 and 94%, respectively. ART‐001 has a pH‐dependent aqueous solubility. It is considered that this unique solubility profile could lead to various absorption of ART‐001 in the gut depending on the individual gastric pH. Indeed, exposure of ART‐001 was much lower with a concomitant dosing with lansoprazole compared to ART‐001 alone. 14 Because the incidences of hyperglycemia, nausea, headache, and some other AEs with ART‐001 increase in an exposure‐dependent manner, long‐term use of ART‐001 requires adequate safety assurance along with maintained efficacy. Therefore, use of the new dry syrup formulation that provides a stable drug exposure in later‐phase clinical studies is supported to select optimal doses for both efficacy and safety.
In part I, the t 1/2 was prolonged, and the CL/F was decreased with increased dose. The lack of statistically significant dose linearity in the AUC0‐inf might be attributable to these changes in the parameters according to the dose. In part II, the plasma concentration had reached a steady‐state on day 5 of the repeated doses of 100 mg; in contrast, the trough concentration still tended to increase on day 5 of the repeated doses of 300 mg, and the time to steady‐state after these doses was unknown. However, it can be assumed that the time to steady‐state after the repeated doses of 300 mg could be prolonged as compared with that after the repeated doses of 100 mg because the t 1/2 after the single doses increased with increased dose. The direct cause of the increase in the t 1/2 with increased dose in the present study remains unknown at present.
The assessment of food effect on PK with the single dose of 100 mg showed a decrease in the C max by ~35%, as well as a decrease in the AUCinf by as little as ~10%. As we hypothesized that the efficacy of ART‐001 is dependent on AUC, the presence or absence of food before administration would not substantially affect the efficacy of ART‐001 in later‐phase studies.
Safety
The study demonstrated that the single doses and repeated doses of ART‐001 in dry syrup formulation at up to 400 and 100 mg, respectively, were safe and well‐tolerated. No deaths and severe and serious AEs occurred in this study. Notable drug‐related AEs were hyperglycemia and blood creatinine increase.
Hyperglycemia is an on‐target effect of ART‐001 because PI3Kα, located downstream of insulin receptor, plays an important role in glucose metabolism. 15 In this study, single and repeated doses of ART‐001 exerted fasting and postprandial hyperglycemia in a dose‐dependent manner. Increased blood glucose levels rapidly recovered to the normal state after ART‐001 administration was completed/terminated. None of the events required the use of drugs, such as insulin and glucose‐lowering agents, and raised clinical concerns over subject safety.
Because blood glucose increase is an on‐target effect of ART‐001, blood glucose response can be used as a target engagement marker for ART‐001. Maximum fold changes in fasting plasma glucose level after the single dose of ART‐001 were increased in a dose‐dependent manner starting from 100 mg. ART‐001 exposure increased by approximately double at the steady‐state after repeated dosing in part II. Therefore, 50 mg once daily may be a lower clinical dose for ART‐001 in the following clinical studies from the target engagement standpoint.
Blood glucose levels remarkably increased at 6 h after administration (2 h after lunch), and greater than 200 mg/dL of blood glucose were observed even in subjects receiving placebo in part I. It was reported that individuals who skipped breakfast exhibit a substantial increase in blood glucose after lunch as compared with those who took breakfast. 16 Thus, the remarkable increase in blood glucose at 6 h after administration in the present study was attributable to skipping breakfast. Indeed, in part I, the mean blood glucose at 6 h after administration of 100 mg in the fasted state (172.8 ± 20.3 mg/dL) was significantly higher than that in the fed state (140.8 ± 8.0 mg/dL).
Significant serum creatinine increase was observed in the 300 mg q.d. group. Therefore, the dosing was discontinued in the group on day 5 and serum cystatin C, urine NGAL, and urine β2 microglobulin were measured for additional testing for safety evaluation. There was no change in serum cystatin C, a specific marker of glomerular filtration rate. Although urine β2 microglobulin levels exceeded the reference value in some of the subjects, urine NGAL levels, a sensitive marker of renal tubular injury, were within the reference value in all subjects. None of these additional renal markers showed clear evidence of a correlation with serum creatinine increase, suggesting that serum creatinine increase might not indicate the drug‐induced acute kidney injury involving the glomerular and/or tubular injuries.
It is well‐recognized that renal transporter inhibition is a potential mechanism of drug‐induced serum creatinine increase which is irrespective of renal dysfunction. 17 For example, the H2‐receptor antagonist cimetidine increases serum creatinine levels without affecting renal filtration rate by inhibiting MATE1 and MATE2‐K that are expressed on the luminal membrane of the renal tubules. 18 According to the US Food and Drug Administration (FDA)'s guidance issued in January 2020, there is a potential drug–drug interaction when the ratio of steady‐state C max of the drug as free base to the half‐maximal inhibitory concentration (IC50) value for in vitro inhibition of transporters is greater than or equal to 0.1. 19 ART‐001 has in vitro inhibitory activity against the renal transporter OCT2 and MATE1 (IC50 of 5.8 and 16 μM, respectively). After the single dose of 300 mg, the ratio of the C max of ART‐001 free base to the IC50 value was 0.63 for OCT2 and 0.23 for MATE1. These findings suggested that the increase in serum creatinine levels after the repeated doses of ART‐001 at 300 mg once daily might be due to the inhibition of tubular creatinine secretion through the inhibition of OCT2 and MATE1. However, because ART‐001 is in an early phase of development, the renal markers, such as serum cystatin C and urine NGAL, should be monitored in subjects involved in later‐phase studies in addition to routine renal function tests to assure patient's safety.
In conclusion, it was demonstrated that the single doses and repeated doses of the ART‐001 dry syrup formulation, at up to 400 and 100 mg, respectively, were safe and well‐tolerated with favorable PK profiles. From the results of the assessment of safety, tolerability, and PKs in the single‐dose and repeated‐dose studies of ART‐001, the dosing regimen of less than or equal to 100 mg once daily was considered appropriate for later‐phase studies. It was also considered feasible to study higher doses while monitoring subjects with full consideration to assure their safety.
AUTHOR CONTRIBUTIONS
A.T., N.U., K.K., and H.N. wrote the manuscript. A.T., N.U., K.K., H.A., and H.N. designed the research. A.T., N.U., K.K., H.A., T.H., and H.N. performed the research. A.T., N.U., K.K., H.A., and H.N. analyzed the data. A.T., N.U., K.K., H.A., and H.N. contributed to develop new formulation of ART‐001.
FUNDING INFORMATION
This study was funded by ARTham Therapeutics Inc. and also was supported by Japan Agency for Medical Research and Development (AMED) under Grant Number 20nk0101215j0003.
CONFLICT OF INTEREST STATEMENT
A.T., K.K., and T.H. are employees of ARTham Therapeutics Inc. and H.N. is CEO of ARTham Therapeutics Inc. A.H. is former employee of ARTham Therapeutics Inc. N.U. served as paid advisor to ARTham Therapeutics Inc.
ACKNOWLEDGMENTS
The authors thank all study participants. The authors also thank the following organizations and their staffs: Nishi Kumamoto Hospital Clinical Pharmacology Center (study site), CTD Inc. and SRD Co., Ltd. (study operation), Sekisui Medical Co., Ltd. (bioanalytical support), Takata Pharmaceutical Co., Ltd. (new formulation development), and Axcelead Drug Discovery Partners Inc. The authors are grateful to AMED for their financial support on this study.
Tanaka A, Uemura N, Kuniyeda K, Ando H, Higashi T, Nagabukuro H. A randomized, placebo‐controlled study to evaluate safety and pharmacokinetics of ART‐001 with a novel oral pediatric formulation in healthy subjects. Clin Transl Sci. 2023;16:1898‐1910. doi: 10.1111/cts.13597
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