Dose Optimization in Oncology Drug Development: An International Consortium for Innovation and Quality in Pharmaceutical Development White Paper.

The landscape of oncology drug development has witnessed remarkable advancements over the last few decades, significantly improving clinical outcomes and quality of life for patients with cancer. Project Optimus, introduced by the U.S. Food and Drug Administration, stands as a groundbreaking endeavor to reform dose selection of oncology drugs, presenting both opportunities and challenges for the field. To address complex dose optimization challenges, an Oncology Dose Optimization IQ Working Group was created to characterize current practices, provide recommendations for improvement, develop a clinical toolkit, and engage Health Authorities. Historically, dose selection for cytotoxic chemotherapeutics has focused on the maximum tolerated dose, a paradigm that is less relevant for targeted therapies and new treatment modalities. A survey conducted by this group gathered insights from member companies regarding industry practices in oncology dose optimization. Given oncology drug development is a complex effort with multidimensional optimization and high failure rates due to lack of clinically relevant efficacy, this Working Group advocates for a case-by-case approach to inform the timing, specific quantitative targets, and strategies for dose optimization, depending on factors such as disease characteristics, patient population, mechanism of action, including associated resistance mechanisms, and therapeutic index. This white paper highlights the evolving nature of oncology dose optimization, the impact of Project Optimus, and the need for a tailored and evidence-based approach to optimize oncology drug dosing regimens effectively.

Exposure-Response Relationships for Pralsetinib in Patients with RET-Altered Thyroid Cancer or RET Fusion-Positive Nonsmall Cell Lung Cancer.

Pralsetinib is a highly potent oral kinase inhibitor of oncogenic RET (rearranged during transfection) fusions and mutations. Pralsetinib received approval from the United States Food and Drug Administration for the treatment of patients with metastatic RET fusion-positive non-small cell lung cancer (NSCLC), and received accelerated approval for the treatment of patients with RET fusion-positive thyroid cancer. Exposure-response (ER) analyses of efficacy were performed separately in patients with thyroid cancer and in patients with NSCLC, but data for all patients were pooled for the safety analysis. ER models were developed with time-varying exposure; the effect of covariates was also examined. For patients with NSCLC, a higher starting dose was associated with improved progression-free survival (PFS), but this improvement did not correlate with a higher exposure overall. Significant covariates included sex and baseline Eastern Cooperative Oncology Group (ECOG) score. For patients with thyroid cancer, a higher exposure was associated with improved PFS. Significant covariates included prior systemic cancer therapy and ECOG score. For safety, higher exposure was associated with a greater risk of grade ≥3 anemia, pneumonia, and lymphopenia. Patients with an ECOG score of ≥1 had an increased risk of grade ≥3 pneumonia. Non-White patients had a lower risk of grade ≥3 lymphopenia. ER analysis revealed that higher pralsetinib exposure was associated with improved PFS in thyroid cancer, but not in NSCLC. However, a higher starting dose (ie, 400 vs ≤300 mg daily) was correlated with better PFS for all indications. Higher exposure was also associated with an increased risk of grade ≥3 adverse events (AEs); however, the overall incidence of these events was acceptably low (≤20%). This analysis supports the use of a 400 mg starting dose of pralsetinib, allowing for dose reduction in the event of AEs.

Single Oral Doses of MK-8507, a Novel Non-Nucleoside Reverse Transcriptase Inhibitor, Suppress HIV-1 RNA for a Week.

BACKGROUND: MK-8507 is a novel HIV-1 non-nucleoside reverse transcriptase inhibitor being developed for treatment of HIV-1 infection. MK-8507 has high antiviral potency in vitro and pharmacokinetic (PK) properties that support once-weekly dosing. SETTING: A phase 1, open-label, proof-of-concept study was conducted in treatment-naive adults with HIV-1 infection to assess monotherapy antiviral activity. METHODS: In 3 sequential panels, participants aged 18-60 years with baseline plasma HIV-1 RNA ≥10,000 copies/mL and CD4+ T-cell count >200/mm3 received a single oral dose of 40, 80, or 600 mg MK-8507 in the fasted state. Participants were assessed for HIV-1 RNA for at least 7 days, PKs for 14 days, and safety and tolerability for 21 days postdose. RESULTS: A total of 18 participants were enrolled (6 per panel). The mean 7-day postdose HIV-1 RNA reduction ranged from ∼1.2 to ∼1.5 log10 copies/mL across the doses assessed. One patient had a viral rebound associated with emergence of an F227C reverse transcriptase variant (per chain-termination method sequencing) 14 days postdose; this variant was found in a second participant by ultra-deep sequencing as an emerging minority variant. MK-8507 PKs were generally dose-proportional and similar to observations in participants without HIV-1 infection in prior studies; mean MK-8507 half life was 56-69 hours in this study. MK-8507 was generally well tolerated at all doses. CONCLUSIONS: The robust antiviral activity, PK, and tolerability of MK-8507 support its continued development as part of a complete once weekly oral regimen for HIV-1 treatment; combination therapy could mitigate the emergence of resistance-associated variants.

A phase 1, open-label study to evaluate the drug interaction between islatravir (MK-8591) and the oral contraceptive levonorgestrel/ethinyl estradiol in healthy adult females.

INTRODUCTION: Hormonal contraceptives are among the most effective forms of reversible contraception, but many other compounds, including some antiretrovirals, have clinically meaningful drug-drug interactions (DDIs) with hormonal contraceptives. Islatravir is a novel human immunodeficiency virus nucleoside reverse transcriptase translocation inhibitor currently in clinical development for treatment and prevention of HIV infection. A phase 1 clinical trial was conducted to evaluate the DDI of islatravir and the combination of oral contraceptive levonorgestrel (LNG)/ethinyl estradiol (EE). METHODS: This was an open-label, two-period, fixed-sequence, DDI clinical trial in healthy, postmenopausal or bilaterally oophorectomized females aged 18 through 65 years in the United States between October 2016 and January 2017. A single dose of LNG 0.15 mg/EE 0.03 mg was given followed by a 7-day washout. Islatravir, 20 mg, was then dosed once weekly for 3 weeks; a single dose of LNG 0.15 mg/EE 0.03 mg was given concomitantly with the third dose of islatravir. Pharmacokinetic samples for plasma LNG and EE concentrations were collected pre-dose and up to 120 hours post-dose in each period. Safety and tolerability were assessed throughout the trial by clinical assessments, laboratory evaluations and examination of adverse events. RESULTS AND DISCUSSION: Fourteen participants were enrolled. The pharmacokinetics of LNG and EE were not meaningfully altered by co-administration with islatravir. For the comparison of (islatravir + LNG/EE)/(LNG/EE alone), the geometric mean ratios (GMRs) (90% confidence intervals [CIs]) for LNG AUC0-inf and Cmax were 1.13 (1.06, 1.20) and 0.965 (0.881, 1.06), respectively. For EE, the GMRs (90% CI) for AUC0-inf and Cmax were 1.05 (0.981, 1.11) and 1.02 (0.971, 1.08), respectively. Co-administration of all three drugs was generally well tolerated. CONCLUSIONS: The results of this trial support the use of LNG/EE contraceptives in combination with islatravir without dose adjustment.

Pharmacokinetic and Safety Profile of the Novel HIV Nonnucleoside Reverse Transcriptase Inhibitor MK-8507 in Adults without HIV.

MK-8507 is a novel HIV-1 nonnucleoside reverse transcriptase inhibitor in clinical development with potential for once-weekly oral administration for the treatment of HIV-1 infection. Two randomized, double-blind, placebo-controlled phase 1 studies in adults without HIV-1 evaluated the safety, tolerability, and pharmacokinetics of single and multiple doses of MK-8507; drug interaction with midazolam (a cytochrome P450 3A4 substrate) and food effect were also assessed. In study 1, 16 participants received oral ascending single doses of MK-8507 (2 to 400 mg) or placebo in an alternating fashion. In study 2, 24 participants received ascending single doses of MK-8507 (400 to 1,200 mg) or placebo and multiple doses (once weekly for 3 weeks) of MK-8507 (100 to 400 mg) or placebo. MK-8507 pharmacokinetics were approximately dose proportional at 2 to 1,200 mg. MK-8507 had a time to maximum concentration of 2 to 7 h and a mean terminal half-life of ∼58 to 84 h. MK-8507 doses of ≥100 mg achieved a plasma concentration at 168 h postdose (7 days) associated with antiviral efficacy. A high-fat meal had no clinically meaningful effect on MK-8507 pharmacokinetics, and MK-8507 400 mg once weekly had no clinically meaningful effect on midazolam pharmacokinetics. Single and multiple doses of MK-8507 were generally well tolerated. No trends with dose and no clinically meaningful changes were observed in vital signs, electrocardiograms, and laboratory safety tests. The pharmacokinetics and safety data are supportive of once-weekly oral administration and support further clinical investigation of MK-8507 for the treatment of HIV-1 infection.

Safety, tolerability, and pharmacokinetics of single- and multiple-dose administration of islatravir (MK-8591) in adults without HIV.

Islatravir (MK-8591) is a nucleoside analogue in development for the treatment and prevention of HIV-1. Two phase 1 trials were conducted during initial evaluation of islatravir: rising single doses (Study 1) and rising multiple doses (Study 2) of oral islatravir in male and female participants without HIV (aged 18-60 years). Safety, tolerability, and pharmacokinetics of islatravir (plasma) and islatravir-triphosphate (peripheral blood mononuclear cells) were assessed. In Study 1, 24 participants, assigned to 1 of 3 panels, received alternating single doses of islatravir in a fasted state from 5 mg to 400 mg, or placebo, over 3 dosing periods; a 30 mg dose was additionally assessed following a high-fat meal. In Study 2, 8 participants per dose received 3 once-weekly doses of 10, 30, or 100 mg islatravir or placebo in a fasted state. For each panel in both trials, 6 participants received active drug and 2 received placebo. Islatravir was generally well-tolerated, with no serious adverse events or discontinuations due to adverse events. Islatravir was rapidly absorbed (median time to maximum plasma concentration 0.5 hours); plasma half-life was 49-61 h; intracellular islatravir-triphosphate half-life was 118-171 h. Plasma exposure increased in an approximately dose-proportional manner; there was no meaningful food effect. There was a modest degree of intracellular islatravir-triphosphate accumulation after multiple weekly dosing. After single oral doses of islatravir greater than or equal to 5 mg, intracellular islatravir-triphosphate levels were comparable to levels associated with efficacy in preclinical studies. These results warrant continued clinical investigation of islatravir.

Atogepant Has No Clinically Relevant Effects on the Pharmacokinetics of an Ethinyl Estradiol/Levonorgestrel Oral Contraceptive in Healthy Female Participants.

The incidence of migraine is higher among women than men and peaks during the reproductive years, when contraceptive medication use is common. Atogepant, a potent, selective antagonist of the calcitonin gene-related peptide receptor-in development for migraine prevention-is thus likely to be used by women taking oral contraceptives. This phase 1, open-label, single-center, 2-period, fixed-sequence study examined the effect of multiple-dose atogepant 60 mg once daily on the single-dose pharmacokinetics of a combination oral contraceptive, ethinyl estradiol 0.03 mg and levonorgestrel 0.15 mg (EE/LNG), in healthy postmenopausal or oophorectomized women. For participants in period 1, a single dose of EE/LNG was followed by a 7-day washout. In period 2, atogepant was given once daily on days 1-17; an oral dose of EE/LNG was coadministered with atogepant on day 14. Plasma pharmacokinetic parameters for EE and LNG were assessed following administration with and without atogepant. Twenty-six participants aged 45-64 years enrolled; 22 completed the study in accordance with the protocol. The area under the concentration-time curve extrapolated to infinity (AUC0-∞ ) of LNG was increased by 19% when administered with atogepant. Coadministration of atogepant and a single dose of EE/LNG did not substantially alter the pharmacokinetics of EE; the ∼19% increase in plasma AUC0-∞ of LNG is not anticipated to be clinically significant. Overall, atogepant alone and in combination with EE/LNG was generally well tolerated, with no new safety signals identified.

Ubrogepant Is Not Associated With Clinically Meaningful Elevations of Alanine Aminotransferase in Healthy Adult Males.

Ubrogepant is a novel, oral calcitonin gene-related peptide (CGRP) receptor antagonist intended for the acute treatment of migraine attacks. Ubrogepant has a chemical structure distinct from previous small-molecule CGRP receptor antagonists that were associated with elevated serum alanine aminotransferase (ALT) in clinical trials. Here, we report overall and hepatic safety data from two placebo-controlled phase I trials of ubrogepant, spray-dried oral compressed tablet (SD-OCT) in healthy male volunteers. Trial A was a pharmacokinetic (PK) trial of single (100-400 mg) and multiple (40-400 mg) ascending doses. Trial B was a dedicated hepatic safety trial assessing daily use of ubrogepant 150 mg for 28 days. Serum ALT (as hepatotoxicity biomarker) and PK data are reported. Ubrogepant was well-tolerated in both trials, with a low incidence of adverse events that did not differ greatly from placebo. Changes in mean ALT levels were minimal and similar to placebo. Over 28 days of treatment, the mean percentage change in ALT from baseline was < 5% at all time points. No participant in either trial demonstrated ALT ≥ 3× upper limit of normal at any time. Ubrogepant SD-OCT demonstrated linear PK appropriate for acute treatment of migraine, with rapid uptake (time of maximum plasma concentration (tmax ): 2-3 hours) and no accumulation with daily use. Overall, there was no evidence of ubrogepant-associated hepatotoxicity with daily doses up to 400 mg for 10 days or with daily ubrogepant 150 mg for 28 days. Supratherapeutic dosing is a useful strategy for characterizing hepatic safety in early drug development.

Investigation of Pharmacokinetic Interactions between Doravirine and Elbasvir-Grazoprevir and Ledipasvir-Sofosbuvir.

Doravirine is a non-nucleoside reverse transcriptase inhibitor for the treatment of human immunodeficiency virus type 1 (HIV-1) infection. Due to the high prevalence of HIV-1 and hepatitis C virus (HCV) coinfection and coadministration of HIV-1 and HCV treatment, potential drug-drug interactions (DDIs) between doravirine and two HCV treatments were investigated in two phase 1 drug interaction trials in healthy participants. Trial 1 investigated the effect of multiple-dose doravirine and elbasvir + grazoprevir coadministration (N = 12), and trial 2 investigated the effect of single-dose doravirine and ledipasvir-sofosbuvir coadministration (N = 14). Doravirine had no clinically relevant effect on the pharmacokinetics of elbasvir, grazoprevir, ledipasvir, sofosbuvir, or the sofosbuvir metabolite GS-331007. Coadministration of elbasvir + grazoprevir with doravirine moderately increased doravirine area under the concentration-time curve from 0 to 24 h (AUC0-24), maximal concentration (Cmax), and concentration 24 h postdose (C24), with geometric least-squares mean ratio (GMR) with 90% confidence intervals (CI) of 1.56 (1.45, 1.68), 1.41 (1.25, 1.58), and 1.61 (1.45, 1.79), respectively. Doravirine AUC0-∞, Cmax, and C24 values increased slightly following coadministration with ledipasvir-sofosbuvir (GMR [90% CI] of 1.15 [1.07, 1.24], 1.11 [0.97, 1.27], and 1.24 [1.13, 1.36], respectively). The modest increases in doravirine exposure are not clinically meaningful based on the therapeutic profile of doravirine. Effects are likely secondary to cytochrome P450 3A and P-glycoprotein inhibition by grazoprevir and ledipasvir, respectively. Coadministration of doravirine with elbasvir + grazoprevir or ledipasvir-sofosbuvir was generally well tolerated. Clinically relevant DDIs are not expected to occur between doravirine and elbasvir-grazoprevir or ledipasvir-sofosbuvir at the therapeutic doses.

Severe Renal Impairment Has Minimal Impact on Doravirine Pharmacokinetics.

Doravirine is a novel nonnucleoside reverse transcriptase inhibitor in development for use with other antiretroviral therapies to treat human immunodeficiency virus type 1 (HIV-1) infection. Doravirine metabolism predominantly occurs via cytochrome P450 3A with <10% of elimination occurring via the renal pathway. As severe renal impairment can alter the pharmacokinetics (PK) of metabolically eliminated drugs, the effect of severe renal impairment on doravirine PK was assessed. A single dose of doravirine 100 mg was administered to subjects aged 18 to 75 years with an estimated glomerular filtration rate (eGFR) of <30 ml/min/1.73 m2 (severe renal impairment group) and healthy controls with an eGFR of ≥80 ml/min/1.73 m2, matched to the mean of the renal impairment group by age (±10 years) and weight (±10 kg). Doravirine plasma concentrations were determined at regular intervals, and safety was monitored throughout. The geometric mean ratios (90% confidence interval) for severe renal impairment/healthy subjects were 1.43 (1.00, 2.04), 1.38 (0.99, 1.92), and 0.83 (0.61, 1.15) for the plasma doravirine area under the curve from zero to infinity (AUC0-∞), plasma concentration at 24 h postdose (C24), and maximum plasma concentration (Cmax), respectively. Doravirine was generally well tolerated in both groups. Based on the overall efficacy, safety, and PK profile of doravirine, the minor effect of severe renal impairment on doravirine PK observed in this study is not considered clinically meaningful. (This study has been registered at ClinicalTrials.gov under identifier NCT02641067.).

Preclinical and translational evaluation of coagulation factor IXa as a novel therapeutic target.

The benefits of novel oral anticoagulants are hampered by bleeding. Since coagulation factor IX (fIX) lies upstream of fX in the coagulation cascade, and intermediate levels have been associated with reduced incidence of thrombotic events, we evaluated the viability of fIXa as an antithrombotic target. We applied translational pharmacokinetics/pharmacodynamics (PK/PD) principles to predict the therapeutic window (TW) associated with a selective small molecule inhibitor (SMi) of fIXa, compound 1 (CPD1, rat fIXa inhibition constant (Ki, 21 nmol/L) relative to clinically relevant exposures of apixaban (rat fXa Ki 4.3 nmol/L). Concentrations encompassing the minimal clinical plasma concentration (C min) of the 5 mg twice daily (BID) dose of apixaban were tested in rat arteriovenous shunt (AVS/thrombosis) and cuticle bleeding time (CBT) models. An I max and a linear model were used to fit clot weight (CW) and CBT. The following differences in biology were observed: (1) antithrombotic activity and bleeding increased in parallel for apixaban, but to a lesser extent for CPD1 and (2) antithrombotic activity occurred at high (>99%) enzyme occupancy (EO) for fXa or moderate (>65% EO) for fIXa. translational PK/PD analysis indicated that noninferiority was observed for concentrations of CPD1 that provided between 86% and 96% EO and that superior TW existed between 86% and 90% EO. These findings were confirmed in a study comparing short interfering (si)RNA-mediated knockdown (KD) modulation of fIX and fX mRNA. In summary, using principles of translational biology to relate preclinical markers of efficacy and safety to clinical doses of apixaban, we found that modulation of fIXa can be superior to apixaban.