Muvalaplin, an Oral Small Molecule Inhibitor of Lipoprotein(a) Formation: A Randomized Clinical Trial.

Importance: Lipoprotein(a) (Lp[a]) is associated with atherosclerotic disease and aortic stenosis. Lp(a) forms by bonding between apolipoprotein(a) (apo[a]) and apo B100. Muvalaplin is an orally administered small molecule that inhibits Lp(a) formation by blocking the apo(a)-apo B100 interaction while avoiding interaction with a homologous protein, plasminogen. Objective: To determine the safety, tolerability, pharmacokinetics, and pharmacodynamic effects of muvalaplin. Design, Setting, and Participants: This phase 1 randomized, double-blind, parallel-design study enrolled 114 participants (55 assigned to a single-ascending dose; 59 assigned to a multiple-ascending dose group) at 1 site in the Netherlands. Interventions: The single ascending dose treatment evaluated the effect of a single dose of muvalaplin ranging from 1 mg to 800 mg or placebo taken by healthy participants with any Lp(a) level. The multiple ascending dose treatment evaluated the effect of taking daily doses of muvalaplin (30 mg to 800 mg) or placebo for 14 days in patients with Lp(a) levels of 30 mg/dL or higher. Main Outcomes and Measures: Outcomes included safety, tolerability, pharmacokinetics, and exploratory pharmacodynamic biomarkers. Results: Among 114 randomized (55 in the single ascending dose group: mean [SD] age, 29 [10] years, 35 females [64%], 2 American Indian or Alaska Native [4%], 50 White [91%], 3 multiracial [5%]; 59 in the multiple ascending dose group: mean [SD] age 32 [15] years; 34 females [58%]; 3 American Indian or Alaska Native [5%], 6 Black [10%], 47 White [80%], 3 multiracial [5%]), 105 completed the trial. Muvalaplin was not associated with tolerability concerns or clinically significant adverse effects. Oral doses of 30 mg to 800 mg for 14 days resulted in increasing muvalaplin plasma concentrations and half-life ranging from 70 to 414 hours. Muvalaplin lowered Lp(a) plasma levels within 24 hours after the first dose, with further Lp(a) reduction on repeated dosing. Maximum placebo-adjusted Lp(a) reduction was 63% to 65%, resulting in Lp(a) plasma levels less than 50 mg/dL in 93% of participants, with similar effects at daily doses of 100 mg or more. No clinically significant changes in plasminogen levels or activity were observed. Conclusion: Muvalaplin, a selective small molecule inhibitor of Lp(a) formation, was not associated with tolerability concerns and lowered Lp(a) levels up to 65% following daily administration for 14 days. Longer and larger trials will be required to further evaluate safety, tolerability, and effect of muvalaplin on Lp(a) levels and cardiovascular outcomes. Trial Registration: ClinicalTrials.gov Identifier: NCT04472676.

Abemaciclib in combination with endocrine therapy for East Asian patients with HR+, HER2- advanced breast cancer: MONARCH 2 & 3 trials.

This post hoc analysis of MONARCH 2 and MONARCH 3 assesses the efficacy, safety, and pharmacokinetics (PK) of abemaciclib in combination with endocrine therapy (ET) in East Asian patients with hormone receptor positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) advanced breast cancer. MONARCH 2 and MONARCH 3 are global, randomized, double-blind, phase 3 studies of abemaciclib/placebo + fulvestrant and abemaciclib/placebo + nonsteroidal aromatase inhibitor (NSAI, anastrozole or letrozole), respectively. The East Asian population comprised 212 (31.7%) of the 669 intent-to-treat (ITT) population in the MONARCH 2 trial and 144 (29.2%) of the 493 ITT patients in the MONARCH 3 trial. In the East Asian population, median progression-free survival (PFS) was significantly prolonged in the abemaciclib arm compared with placebo in both MONARCH 2 (hazard ratio [HR], 0.520; 95% confidence interval [CI], 0.362 to 0.747; P < .001; median: 21.2 vs 11.6 months) and MONARCH 3 (HR, 0.326; 95% CI, 0.200 to 0.531, P < .001; median: not reached vs 12.82 months). Diarrhea (MONARCH 2: 90%; MONARCH 3: 88%) and neutropenia (MONARCH 2: 68%; MONARCH 3: 58%) were the most frequent adverse events observed in the East Asian populations. Abemaciclib exposures and PK were similar in East Asians and the non-East Asian populations of both trials. Abemaciclib in combination with ET in the East Asian populations of MONARCH 2 and MONARCH 3 provided consistent results with the ITT populations, demonstrating improvements in efficacy with generally tolerable safety profiles for patients with HR+, HER2- advanced breast cancer.

Abemaciclib Does Not Have a Clinically Meaningful Effect on Pharmacokinetics of CYP1A2, CYP2C9, CYP2D6, and CYP3A4 Substrates in Patients with Cancer.

Abemaciclib is an orally administered, potent inhibitor of cyclin-dependent kinases 4 and 6 and is metabolized extensively by CYP3A4. The effects of abemaciclib on several CYPs were qualified in vitro and subsequently evaluated in a clinical study. In vitro, human hepatocytes were treated with vehicle, abemaciclib, or abemaciclib metabolites [N-desethylabemaciclib (M2) or hydroxyabemaciclib (M20)]. mRNA levels for eight CYPs were measured using reverse-transcription quantitative polymerase chain reaction, and, additionally, catalytic activities for three CYPs were determined. In the clinical study, adult patients with cancer received a drug cocktail containing CYP substrates [midazolam (3A), warfarin (2C9), dextromethorphan (2D6), and caffeine (1A2)] either alone or in combination with abemaciclib. Plasma pharmacokinetics (PK) samples were analyzed for all substrates, caffeine metabolite paraxanthine, and abemaciclib; polymorphisms of CYP2C9, CYP2D6, CYP3A4, and CYP3A5 were evaluated. In vitro, downregulation of CYP mRNA, including 1A2, 2B6, 2C8, 2C9, 2D6, and 3A, by abemaciclib and/or M2 and M20 was observed at clinically relevant concentrations. In humans, abemaciclib did not affect the PK of CYP2D6 or CYP2C9 substrates. Minor statistically significant but clinically irrelevant changes were observed for midazolam [area under the concentration versus time curve from zero to infinity (AUC0-inf) (13% lower), Cmax (15% lower)], caffeine [AUC0-inf (56% higher)], and paraxanthine: caffeine [area under the concentration versus time curve from 0 to 24 hours ratio (was approximately 30% lower)]. However, given the magnitude of the effect, these changes are not considered clinically relevant. In conclusion, the downregulation of CYP mRNA mediated by abemaciclib in vitro did not translate into clinically meaningful drug-drug interactions in patients with cancer. SIGNIFICANCE STATEMENT: Despite observations that abemaciclib alters the mRNA of various CYP isoforms in vitro, a clinical study using a drug cocktail approach found no clinically meaningful drug-drug interactions between abemaciclib and a range of CYP substrates [midazolam (CYP3A4), S-warfarin (CYP2C9), dextromethorphan (CYP2D6), and caffeine (CYP1A2)]. This lack of translation suggests greater understanding of mechanisms of CYP downregulation is needed to accurately predict clinical drug-drug interaction risk from in vitro data.

An innovative, multi-arm, complete phase 1b study of the novel anti-cancer agent tasisulam in patients with advanced solid tumors.

BACKGROUND: This phase Ib study used a parallel, multi-arm design to examine tasisulam-sodium (hereafter tasisulam), a drug with complex pharmacology, combined with standard chemotherapies in patients with advanced solid tumors, with the ultimate goal of accelerating drug development. METHODS: Patients received escalating doses of tasisulam (3 + 3 schema; target Cmax 300-400 µg/mL) every 28 days plus 1,000 mg/m(2) gemcitabine HCl (days 1 and 15), 60 mg/m(2) docetaxel, 200 mg/m(2)/day temozolomide, 75 mg/m(2) cisplatin, or 150 mg/day erlotinib. Following dose-escalation, patients were enrolled into specific tumor subtype arms, chosen based on the established activity of the standard agent. Because tasisulam is highly albumin-bound, patients in the tumor-specific confirmation arms were dosed targeting specific albumin-corrected exposure ranges (AUCalb) identified during dose-escalation (3,500 h*µg/mL [75th percentile] for docetaxel, temozolomide, and cisplatin; 4,000 h*µg/mL for gemcitabine and erlotinib). RESULTS: A total of 234 patients were enrolled. The safety profile of tasisulam with standard chemotherapies was sufficient to allow enrollment into the dose-confirmation phase in all arms. The primary dose-limiting toxicities were hematologic (thrombocytopenia and neutropenia). The most common grade ≥3 drug-related treatment-emergent adverse event was neutropenia, with the highest incidence in the docetaxel arm. CONCLUSIONS: The multi-arm design allowed the efficient determination of the maximum tolerated dose of tasisulam across multiple combinations, and a preliminary characterization of pharmacokinetics, safety, and potential efficacy. Although enrollment into all planned groups was not completed due to termination of compound development, these data support the feasibility of this approach for accelerated cancer drug development, even for drugs with complex pharmacology.

A randomized, open-label clinical trial of tasisulam sodium versus paclitaxel as second-line treatment in patients with metastatic melanoma.

BACKGROUND: Tasisulam sodium (hereafter referred to as tasisulam) is a novel, highly albumin-bound agent that demonstrated activity in a phase 2 melanoma study. METHODS: In this open-label phase 3 study, patients with AJCC stage IV melanoma received tasisulam (targeting an albumin-corrected exposure of 1200-6400 h (hour).µg/mL on day 1) or paclitaxel (80 mg/m(2) on days 1, 8, and 15) every 28 days as second-line treatment. RESULTS: The study was placed on clinical hold after randomization of 336 patients when a safety review indicated an imbalance of possibly drug-related deaths in the tasisulam arm. Efficacy results for tasisulam versus paclitaxel revealed a response rate of 3.0% versus 4.8%, a median progression-free survival of 1.94 months versus 2.14 months (P = .048), and a median overall survival of 6.77 months versus 9.36 months (P = .121). The most common drug-related grade ≥3 laboratory toxicities (graded according to Common Terminology for Adverse Events [version 3.0]) were thrombocytopenia (18.9%) for patients treated with tasisulam and neutropenia/leukopenia (8.7%) among those receiving paclitaxel. There were 13 possibly related deaths reported to occur on the study, with the majority occurring during cycle 2 in the setting of grade 4 myelosuppression, all in the tasisulam arm. Investigation of the unexpectedly high rate of hematologic toxicity revealed a subset of patients with low tasisulam clearance, leading to drug accumulation and high albumin-corrected exposure in cycle 2. CONCLUSIONS: Although the study was stopped early because of safety issues in the tasisulam arm, tasisulam was considered unlikely to be superior to paclitaxel, and paclitaxel activity in the second-line treatment of melanoma was much lower than expected. The toxicity imbalance was attributed to an unexpectedly low tasisulam clearance in a subset of patients, underscoring the importance of pharmacokinetic monitoring of compounds with complex dosing, even in late-phase studies.

Abemaciclib does not increase the corrected QT interval in healthy participants.

Abemaciclib is an orally administered, potent, and selective small molecule inhibitor of cyclin-dependent kinases 4 and 6, approved for advanced or metastatic breast cancer. This study aimed to use an exposure-response approach to investigate the effect of abemaciclib and its active metabolites (M2 and M20) on QTc interval and delay in cardiac repolarization at clinically relevant exposures. This was a single-blind, randomized, and placebo-controlled study of ascending doses of abemaciclib. Thirty-five healthy participants were administered a single dose of 200-600 mg abemaciclib. Twelve-lead electrocardiogram tracings and pharmacokinetic samples were collected serially pre- and post-dose. The primary objective was to study the relationship between abemaciclib and its active metabolites (M2 and M20) and QTc interval following ascending oral doses of abemaciclib. The secondary objective included evaluating the safety and tolerability of single ascending doses of abemaciclib in healthy participants. Exposure-response analysis demonstrated that there was no significant relationship between placebo-corrected change from baseline QTcF (ΔΔQTcF), abemaciclib, and metabolite plasma concentrations. Additionally, the ΔΔQTcF slopes of abemaciclib, its metabolites, and total analyte concentrations were not statistically different from zero. Single doses of abemaciclib, up to 400 mg, were well-tolerated by healthy participants; however, at the 600 mg dose (three times the highest registered dose), the frequency and severity of treatment-related gastrointestinal events (primarily diarrhea, nausea, and vomiting) increased. In conclusion, single doses of abemaciclib, up to 400 mg, had no statistically or clinically relevant effects on QTc, and abemaciclib was well tolerated up to a dose of 400 mg in this study.

Predicting Clinical Effects of CYP3A4 Modulators on Abemaciclib and Active Metabolites Exposure Using Physiologically Based Pharmacokinetic Modeling.

Abemaciclib, a selective inhibitor of cyclin-dependent kinases 4 and 6, is metabolized mainly by cytochrome P450 (CYP)3A4. Clinical studies were performed to assess the impact of strong inhibitor (clarithromycin) and inducer (rifampin) on the exposure of abemaciclib and active metabolites. A physiologically based pharmacokinetic (PBPK) model incorporating the metabolites was developed to predict the effect of other strong and moderate CYP3A4 inhibitors and inducers. Clarithromycin increased the area under the plasma concentration-time curve (AUC) of abemaciclib and potency-adjusted unbound active species 3.4-fold and 2.5-fold, respectively. Rifampin decreased corresponding exposures 95% and 77%, respectively. These changes influenced the fraction metabolized via CYP3A4 in the model. An absolute bioavailability study informed the hepatic and gastric availability. In vitro data and a human radiolabel study determined the fraction and rate of formation of the active metabolites as well as absorption-related parameters. The predicted AUC ratios of potency-adjusted unbound active species with rifampin and clarithromycin were within 0.7- and 1.25-fold of those observed. The PBPK model predicted 3.78- and 7.15-fold increases in the AUC of the potency-adjusted unbound active species with strong CYP3A4 inhibitors itraconazole and ketoconazole, respectively; and 1.62- and 2.37-fold increases with the concomitant use of moderate CYP3A4 inhibitors verapamil and diltiazem, respectively. The model predicted modafinil, bosentan, and efavirenz would decrease the AUC of the potency-adjusted unbound active species by 29%, 42%, and 52%, respectively. The current PBPK model, which considers changes in unbound potency-adjusted active species, can be used to inform dosing recommendations when abemaciclib is coadministered with CYP3A4 perpetrators.

Development and Application of a Mechanistic Population Modeling Approach to Describe Abemaciclib Pharmacokinetics.

Abemaciclib is an oral anticancer drug that inhibits cyclin dependent kinases 4 and 6 and is metabolized by cytochrome P450 3A in the intestines and liver to active metabolites. The objectives were (1) to develop a mechanistic model to characterize the pharmacokinetics (PK) of the active moieties and investigate the effect of patient factors and (2) apply the model to dat from two phase III breast cancer trials of abemaciclib in combination with endocrine therapy. To develop the model, data from seven phase I studies and two phase II studies including 421 patients with cancer and 65 healthy individuals were pooled for nonlinear mixed effects modeling. The PK was similar between patients and healthy subjects, and the effects of diarrhea, formulation, race, and patient covariates on exposure were negligible. Application of the model confirmed its predictive performance and that abemaciclib PK did not change when coadministered with endocrine therapy.

Abemaciclib Inhibits Renal Tubular Secretion Without Changing Glomerular Filtration Rate.

Abemaciclib, an inhibitor of cyclin dependent kinases 4 and 6, is indicated for metastatic breast cancer treatment. Reversible increases in serum creatinine levels of ~15-40% over baseline have been observed following abemaciclib dosing. This study assessed the in vitro and clinical inhibition of renal transporters by abemaciclib and its metabolites using metformin (a clinically relevant transporter substrate), in a clinical study that quantified glomerular filtration and iohexol clearance. In vitro, abemaciclib inhibited metformin uptake by organic cation transporter 2, multidrug and toxin extrusion (MATE)1, and MATE2-K transporters with a half-maximal inhibitory concentration of 0.4-3.8 µM. Clinically, abemaciclib significantly increased metformin exposure but did not significantly affect measured glomerular filtration rate, serum neutrophil gelatinase-associated lipocalin (NGAL), serum cystatin-C, or the urinary markers of kidney tubular injury, NGAL and kidney injury molecule-1.

A Population Pharmacokinetic and Pharmacodynamic Analysis of Abemaciclib in a Phase I Clinical Trial in Cancer Patients.

BACKGROUND AND OBJECTIVES: Abemaciclib, a dual inhibitor of cyclin-dependent kinases 4 and 6, has demonstrated clinical activity in a number of different cancer types. The objectives of this study were to characterize the pharmacokinetics of abemaciclib in cancer patients using population pharmacokinetic (popPK) modeling, and to evaluate target engagement at clinically relevant dose levels. METHODS: A phase I study was conducted in cancer patients which incorporated intensive pharmacokinetic sampling after single and multiple oral doses of abemaciclib. Data were analyzed by popPK modeling, and patient demographics contributing to pharmacokinetic variability were explored. Target engagement was evaluated by combining the clinical popPK model with a previously developed pre-clinical pharmacokinetic/pharmacodynamic model. RESULTS: The pharmacokinetic analysis incorporated 4012 plasma concentrations from 224 patients treated with abemaciclib at doses ranging from 50 to 225 mg every 24 h and 75 to 275 mg every 12 h. A linear one-compartment model with time- and dose-dependent relative bioavailability (F rel) adequately described the pharmacokinetics of abemaciclib. Serum albumin and alkaline phosphatase were the only significant covariates identified in the model, the inclusion of which reduced inter-individual variability in F rel by 10.3 percentage points. By combining the clinical popPK model with the previously developed pre-clinical pharmacokinetic/pharmacodynamic model, the extent of target engagement in skin in cancer patients was successfully predicted. CONCLUSION: The proportion of abemaciclib pharmacokinetic variability that can be attributed to patient demographics is negligible, and as such there are currently no dose adjustments recommended for adult patients of different sex, age, or body weight. TRIAL REGISTRATION: NCT01394016 (ClinicalTrials.gov).