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In this first-in-human phase 1 study (NCT02964013; MK-7684-001), we investigated the safety and efficacy of the anti-TIGIT (T cell immunoglobulin and ITIM domain) antibody vibostolimab as monotherapy or in combination with pembrolizumab.Part A enrolled patients with advanced solid tumors, and part B enrolled patients with non-small-cell lung cancer (NSCLC). Patients received vibostolimab 2.1-700 mg alone or with pembrolizumab 200 mg in part A and vibostolimab 200 mg alone or with pembrolizumab 200 mg in part B. Primary endpoints were safety and tolerability. Secondary endpoints included pharmacokinetics and objective response rate (ORR) per RECIST v1.1.Part A enrolled 76 patients (monotherapy, 34; combination therapy, 42). No dose-limiting toxicities were reported. Across doses, 56% of patients receiving monotherapy and 62% receiving combination therapy had treatment-related adverse events (TRAEs); grade 3-4 TRAEs occurred in 9% and 17% of patients, respectively. The most common TRAEs were fatigue (15%) and pruritus (15%) with monotherapy and pruritus (17%) and rash (14%) with combination therapy. Confirmed ORR was 0% with monotherapy and 7% with combination therapy. In part B, 39 patients had anti-PD-1 (programmed cell death protein 1)/PD-L1 (programmed death-ligand 1)-naive NSCLC (all received combination therapy), and 67 had anti-PD-1/PD-L1-refractory NSCLC (monotherapy, 34; combination therapy, 33). In patients with anti-PD-1/PD-L1-naive NSCLC: 85% had TRAEs-the most common were pruritus (38%) and hypoalbuminemia (31%); confirmed ORR was 26%, with responses occurring in both PD-L1-positive and PD-L1-negative tumors. In patients with anti-PD-1/PD-L1-refractory NSCLC: 56% receiving monotherapy and 70% receiving combination therapy had TRAEs-the most common were rash and fatigue (21% each) with monotherapy and pruritus (36%) and fatigue (24%) with combination therapy; confirmed ORR was 3% with monotherapy and 3% with combination therapy.Vibostolimab plus pembrolizumab was well tolerated and demonstrated antitumor activity in patients with advanced solid tumors, including patients with advanced NSCLC.

Despite numerous publications emphasizing the value of dose finding, drug development in oncology is dominated by the mindset that higher dose provides higher efficacy. Examples of dose finding implemented by biopharmaceutical firms can change this mindset. The purpose of this article is to outline a pragmatic dose selection strategy for immuno-oncology (IO) and other targeted monoclonal antibodies (mAbs). The approach was implemented for pembrolizumab. Selecting a recommended phase II dose (RP2D) with a novel mechanism of action is often challenging due to uncertain relationships between pharmacodynamics measurements and clinical end points. Additionally, phase I efficacy and safety data are generally inadequate for RP2D selection for IO mAbs. Here, the RP2D was estimated based on phase I (clinical study KN001 A and A2) pharmacokinetics data as the dose required for target saturation, which represents a surrogate for maximal pharmacological effect for antagonist mAbs. Due to limitations associated with collecting and analyzing tumor biopsies, characterizing intratumoral target engagement (TE) is challenging. To overcome this gap, a physiologically-based pharmacokinetic model was implemented to predict intratumoral TE. As tumors are spatially heterogeneous, TE was predicted in well-vascularized and poorly vascularized tumor regions. Additionally, impact of differences in target expression, for example, due to interindividual variability and cancer type, was simulated. Simulations showed that 200 mg every 3 weeks can achieve ≥ 90% TE in clinically relevant scenarios, resulting in the recommendation of 200 mg every 3 weeks as the RP2D. Randomized dose comparison studies (KN001 B2 and D) showing similar efficacy over a fivefold dose/exposure range confirmed the RP2D as the pivotal dose.

Background Pembrolizumab is approved for multiple cancer types at 200 mg and 2 mg/kg dose every 3 weeks (Q3W). We used a model-based approach to compare the exposure of pembrolizumab 400 mg dose every 6 weeks (Q6W) with the Q3W regimens. Methods The Q6W dose was selected by matching exposure with the 200 mg and 2 mg/kg Q3W doses. Concentration-time profiles were simulated using the established population pharmacokinetic model of pembrolizumab based on 2993 subjects from five clinical trials across tumour types. Efficacy was bridged by evaluating projections of average concentration over the dosing interval (Cavg) and trough concentration (Cmin) at steady state (ss). Safety was bridged by ensuring that concentrations were below those at 10 mg/kg dose every 2 weeks (Q2W), the maximum clinical dose. Results The 400 mg Q6W dose had similar predicted exposure (Cavg,ss, geometric mean ∼1% higher) as the 200 mg Q3W dose. Fewer than 1% of subjects had transiently lower Cmin,ss than that observed for 200 mg and 2 mg/kg Q3W. Despite these reductions, similar target saturation is expected. The predicted peak concentrations (Cmax,ss) for 400 mg Q6W were substantially (∼65%) lower than the 10 mg/kg Q2W dose. Conclusions Exposures expected for pembrolizumab 400 mg Q6W were similar to the 200 mg and 2 mg/kg Q3W and below the 10 mg/kg Q2W regimens. Established exposure-response relationships for pembrolizumab over a 5-fold dose range (2 mg/kg Q3W to 10 mg Q2W) support that clinical efficacy and safety of 400 mg Q6W would be similar to the 200 mg and 2 mg/kg Q3W doses across tumour types. Clinical trial registration numbers NCT01295827, NCT01704287, NCT01866319, NCT01905657, NCT02142738.

Relebactam is a small-molecule β-lactamase inhibitor developed as a fixed-dose combination with imipenem/cilastatin. The pharmacokinetics of relebactam and imipenem across 10 clinical studies were analyzed using data from adult healthy volunteers and patients with bacterial infections. Renal function estimated by creatinine clearance significantly affected the clearance of both compounds, whereas weight and health status were of less clinical significance. Simulations were used to calculate probability of joint target attainment (ratio of free drug area under the curve from 0 to 24 hours to minimum inhibitory concentration (MIC) for relebactam and percentage of time the free drug concentration exceeded the MIC for imipenem) for the proposed imipenem/relebactam dose of 500/250 mg, with adjustments for patients with renal impairment, administered as a 30-minute intravenous infusion four times daily. These dosing regimens provide sufficient antibacterial coverage (MIC ≤ 4 μg/mL) for all renal groups.

Background: The anti-TIGIT antibody vibo in combination with pembro has shown promising antitumor activity in anti-PD-1/PD-L1-naive NSCLC. In the ongoing phase 1 trial (NCT02964013), we evaluated the safety and efficacy of these drugs given in combination (vibo + pembro) or as a coformulation (vibo/pembro) for the treatment of ovarian cancer naive to PD-1/PD-L1 inhibitors. Methods: Patients had locally advanced unresectable or metastatic ovarian cancer naive to PD-1/PD-L1 inhibitors that progressed after ≥1 line of therapy, including platinum therapy. Patients were nonrandomly assigned to receive vibo (200 mg IV Q3W) + pembro (200 mg IV Q3W) or as the coformulation (vibo/pembro) at the same dose for ≤35 cycles (~2 years) or until disease progression (PD), toxicity, or patient withdrawal. Primary end points were safety and tolerability. Secondary and exploratory end points included PK, objective response rate (ORR), duration of response (DOR), and progression-free survival (PFS) by investigator review per RECIST v1.1. PD-L1 positivity was defined as a combined positive score (CPS) of ≥1 or when CPS was missing, as a tumor proportion score of ≥1% or as a mononuclear immune cell density score of ≥2. Results: Of 61 patients enrolled, 21 received vibo + pembro, and 40 received vibo/pembro. Median age was 58 years; 48% of patients had ECOG performance status 1, 15% had BRCA1 and/or BRCA2 mutations, 87% received ≥2 lines of prior therapy (66%, bevacizumab; 41%, PARP inhibitor), and 74% had platinum-resistant disease (PD Conclusions: Safety and PK were comparable with vibo + pembro combination and the vibo/pembro coformulation in patients with platinum-resistant locally advanced unresectable or metastatic ovarian cancer naive to PD-1/PD-L1 inhibitors. Antitumor activity was equivalent between the combination and coformulation, with responses limited to PD-L1-positive tumors. Vibo/pembro coformulation may offer a safe and convenient treatment option in these patients; further investigations of antitumor activity by PD-L1 status are needed. Citation Format: Ruth Perets, Martin Gutierrez, Sun Young Rha, Sarah Taylor, Brian Stein, Antonio Jimeno, Ira Winer, Diana Chen, Tanya Keenan, Mohini Rajasagi, Mallika Lala, Jane Healy, Ronnie Shapira-Frommer. Safety and efficacy of vibostolimab (vibo) plus pembrolizumab (pembro) and coformulation of vibo/pembro in ovarian cancer naive to PD-1/PD-L1 inhibitors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT180.

In patients with renal insufficiency, dose adjustments based on creatinine clearance and body weight have been a component of imipenem dosage instructions. The objective of the current analysis was to provide revised dosing recommendations by evaluating the impact of creatinine clearance and body weight on the pharmacokinetics of imipenem. A population pharmacokinetics model was developed with data from 465 patients and 3300 pharmacokinetic samples. Simulations provided data to support revision of the dosing recommendations to remove body weight-adjusted dosing, and the analysis formed the basis for updates that are reflected on the current imipenem label for both the United States and Europe. The optimized regimen provided an advantage in terms of improved target attainment at breakpoint minimum inhibitory concentration values of 1 and 2 μg/mL, as low-body-weight patients maintained >90% probability of target attainment compared to

Objectives A wide range of objective response rates (ORRs: 0–53%) among available treatments in patients with R/M HNSCC with progression on or after platinum-based chemotherapy (PBT) renders treatment selection a challenge. This systematic literature review (SLR) was intended to aid clinical decision-making by classifying historical studies to accurately characterize the response in second-line (progression on/after platinum-based therapy), and third-line (progression on/after platinum and cetuximab/other drug) settings. Methods SLR was performed to characterize the ORR, duration of response (DOR), progression-free survival (PFS) and overall survival (OS) with therapies recommended by the National Comprehensive Cancer Network (NCCN) guidelines. Clinical trials published in English between January 1, 1985, and September 30, 2016 were identified by searching the PubMed (Medline), Cochrane, and Embase databases. Results The SLR identified 34 key studies in second-line R/M HNSCC patients, and one of these included a third-line patient cohort. However, several studies did not enrol a strictly second-line population. Response in a true second-line setting was elucidated by categorizing the studies using a novel framework defined according to the extent to which enrolled patients were second-line. Only seven studies were strictly second-line, with an estimated pooled ORR of 4% (95% CI = 2–8%; N = 414) for methotrexate and 11% (95% CI = 7–15%; N = 235) for cetuximab, and a reported ORR of 14% (N = 78) from a single study of paclitaxel. The median DOR was limited with cetuximab (∼4 months) and paclitaxel (∼7 months), and not reported for methotrexate. Median PFS or time to progression (TTP) ranged from 1.7 to 3.5 months, and median OS from 4.3 to 6.7 months. The ORR in the only third-line study was 0% (95% CI = 0–7; N = 53) for the platinum + cetuximab combination. Conclusion These findings emphasize the historically bleak prognoses in patients with R/M HNSCC following PBT progression. Anti-PD-1 therapies, namely pembrolizumab and nivolumab, represent novel treatment options that may improve clinical outcomes.

Background: Pembrolizumab is approved for use across multiple cancers at a dose of 200 mg or 2 mg/kg Q3W or 400 mg Q6W administered as an IV infusion. Alternative subcutaneous (SC) formulations can provide added convenience and flexibility in the clinic. KEYNOTE-555 (NCT03665597) Cohort A is an open-label, phase 1 study examining the relative bioavailability of 2 different concentrations of pembrolizumab SC formulations versus pembrolizumab IV. Methods: Patients with advanced melanoma were randomly assigned to receive (in a cross-over design) 1 dose of pembrolizumab 200 mg IV and 2 doses of pembrolizumab 285 mg SC (one of each SC formulation) during the first 3 treatment cycles; thereafter, all patients receive pembrolizumab IV for up to 2 years. Bayesian analysis of pembrolizumab serum concentration data collected from 31 patients through cycles 1, 2, and 3 in the current study and previously published pembrolizumab IV data were used to characterize the pharmacokinetics (PK) of pembrolizumab SC. Distribution and elimination parameters, time-dependent clearance, and covariate effects from the previously established pembrolizumab IV PK model were used, as these phases were expected to be similar for IV and SC administrations. Injection site reactions were evaluated by monitoring patients for local skin reactions approximately 1 hour after pembrolizumab SC or IV administration during the first 3 cycles, and through use of a pt questionnaire following monitoring. Results: The model simultaneously described pembrolizumab PK after IV and SC administrations. The SC absorption was characterized by a first-order absorption rate with lag time and bioavailability parameters. The PK of both pembrolizumab SC formulations were similar with an estimated bioavailability of 64% (95% CI, 54-74); this is consistent with the reported bioavailability of other SC monoclonal antibodies that range from 50% to 85%. Inclusion of a covariate effect of the SC formulation on bioavailability, lag time, or absorption rate was not statistically significant, indicating no significant difference between the 2 SC formulations in the absorption phase. In addition, no anti-drug antibody was observed after 3 treatment cycles. In general, pembrolizumab SC formulations were well tolerated over the first 3 cycles, with no significant injection-site reactions. Two grade 2 adverse events (AEs) of pruritus and rash were reported from the SC formulations and IV infusion, respectively; the other AEs were grade 1. Conclusions: The bioavailability of SC pembrolizumab was characterized from KEYNOTE-555 Cohort A data. SC formulations will be further assessed clinically in other tumor types. Citation Format: Conrad R. Jacobs, Bernardo Leon Rapoport, Graham Lawrence Cohen, Mallika Lala, Carolina De Miranda Silva, Pavan Vaddady, Ferdous Gheyas, Dinesh de Alwis, Vikram Sinha, Omobolaji Oyekunle Akala, Elliot Chartash, Lokesh Jain. Pembrolizumab bioavailability after subcutaneous administration: analysis from the KEYNOTE-555 Cohort A in metastatic melanoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr CT143.

9541 Background: In KEYNOTE-555, a model-based approach suggested expected drug exposure with pembro 400 mg Q6W is similar to that observed with approved doses of pembro 200 mg or 2 mg/kg Q3W. The pembro Q6W dose is now approved. We present interim efficacy, safety and PK of 1L pembro 400 mg Q6W for patients (pts) with advanced melanoma in KEYNOTE-555 Cohort B (NCT03665597). Methods: Eligible pts had unresectable stage III or IV melanoma, ECOG PS ≤1, and no prior systemic therapy for advanced disease.Pts received pembro 400 mg Q6W for up to 18 cycles (≈2 years).The primary efficacy endpoint was ORR per RECIST v1.1 by blinded independent central review (BICR). Secondary endpoints included PFS by BICR per RECIST v1.1 and safety. PK profile and exposure were evaluated for cycle 1 and steady state (cycle 4). Results: Between May 2019 and Jan 2020, 101 pts were enrolled and received ≥1 dose of pembro. Baseline characteristics were generally similar to pt cohorts of historical pembro studies in advanced melanoma. As of the data cutoff date of August 6, 2020, all pts had ≥6 mo of follow-up and 40.6% of pts had discontinued study treatment. Median (range) duration of treatment and doses administered were 8.2 mo (1 day–13.9 mo) and 6 (1–11) doses, respectively. Observed exposure with pembro 400 mg Q6W had lower variability than model predictions and was within PK parameters from clinical experience with other pembro regimens (Table). ORR was 50.5% (95% CI 40.4–60.6). 12.9% of pts had CR and 37.6% had PR. Median PFS was 13.8 mo (95% CI 3.0–not reached). Estimated PFS rates were 56.5% at 6 mo and 54.3% at 12 mo. Treatment-related AEs of any grade occurred in 79.2% of pts (grade 3–4: 6.9% of pts; no deaths due to a treatment-related AE). The most common immune-mediated AEs were hyperthyroidism (6.9%) and hypothyroidism (6.9%). Conclusions: 1L treatment with pembro 400 mg Q6W yielded a clinically meaningful ORR in pts with advanced melanoma. PK, efficacy and safety results from KEYNOTE-555 Cohort B support prior findings from the model-based assessment and indicate that the benefit-risk profile for the more practical pembro 400 mg Q6W regimen is consistent with that of 200 mg or 2 mg/kg Q3W regimens. Clinical trial information: NCT03665597. [Table: see text]

Aims Two phase 1, open-label studies were conducted to investigate the effect of renal impairment (RI) and organic anion transporter (OAT) inhibition on pharmacokinetics (PK) and safety of relebactam (REL) plus imipenem/cilastatin (IMI). Methods Study PN005 evaluated the PK of REL (125 mg) plus IMI (250 mg) in participants with RI vs healthy controls. Study PN019 evaluated the PK of REL (250 mg) and imipenem (500 mg; dosed as IMI) with/without probenecid (1 g; OAT inhibitor) in healthy adults. Results Geometric mean ratios (RI/healthy matched controls) of area under the concentration-time curve from time 0 to infinity (AUC0-∞ ; 90% confidence interval) for REL, imipenem and cilastatin increased as RI increased from mild (1.6 [1.1, 2.4], 1.4 [1.1, 1.8] and 1.6 [1.0, 2.5], respectively) to severe (4.9 [3.4, 7.0], 2.5 [1.9, 3.3] and 5.6 [3.6, 8.6], respectively). For all 3 analytes, plasma and renal clearance decreased and corresponding plasma apparent terminal half-life increased with increasing RI. Geometric mean ratios ([probenecid+IMI/REL]/[IMI/REL]) of plasma exposure for REL and imipenem were 1.24 (1.19, 1.28) and 1.16 (1.13, 1.20), respectively. The dose fraction excreted (fe) in the urine decreased progressively from mild to severe RI. Probenecid reduced renal clearance of REL and imipenem by 25 and 31%, respectively. Compared with IMI/REL, coadministration of IMI/REL with probenecid yielded lower fe for REL and imipenem. In both studies, treatment was well tolerated; there were no serious adverse events or discontinuations due to adverse events. Conclusion RI increased plasma exposure and similarly decreased clearance of REL, imipenem and cilastatin; IMI/REL dose adjustment (fixed-ratio) will be required for patients with RI. Probenecid had no clinically meaningful impact on the PK of REL or imipenem.

The effects of supratherapeutic doses of intravenous (IV) relebactam on duration of ventricular depolarization and subsequent repolarization were assessed in a thorough QT/corrected QT study. This was a single-dose, double-blind (relebactam only), randomized, placebo- and positive-controlled, 3-period, balanced crossover study in healthy participants. Participants received in randomized order, and separated by a washout (≥4 days), a single dose of IV relebactam 1150 mg, oral moxifloxacin 400 mg (open-label positive control), and IV placebo. Least squares mean and 2-sided 90% confidence interval for change from baseline in population-derived corrected QT intervals for relebactam, moxifloxacin, and placebo were estimated for 24 hours. The upper limit of the 90% confidence interval of all least squares mean population-derived corrected QT treatment differences from placebo was not >10 milliseconds at any time point for 24 hours. Corrected QT assay sensitivity was confirmed with moxifloxacin treatment. Analysis of electrocardiogram parameters resulted in no additional cardiac safety concerns. Overall, a supratherapeutic dose of relebactam yielded no cardiac safety events; the 1150-mg supratherapeutic dose (4.6-fold above the 250-mg therapeutic dose) was not associated with QT prolongation or other abnormal cardiodynamic parameters. This study lends additional support to relebactam's use as a β-lactamase inhibitor in antimicrobial therapy.

Pembrolizumab is a potent, humanized, monoclonal anti–programmed death 1 antibody that has demonstrated effective antitumor activity and acceptable safety in multiple tumor types. Therapeutic biologics can result in the development of antidrug antibodies (ADAs), which may alter drug clearance and neutralize target binding, potentially reducing drug efficacy; such immunogenicity may also result in infusion reactions, anaphylaxis, and immune complex disorders. Pembrolizumab immunogenicity and its impact on exposure, safety, and efficacy was assessed in this study. Pembrolizumab immunogenicity was assessed in 3655 patients with advanced or metastatic cancer treated in 12 clinical studies. Patients with melanoma, non–small cell lung cancer, head and neck squamous cell carcinoma, colorectal cancer, urothelial cancer, and Hodgkin lymphoma were treated with pembrolizumab at 2 mg/kg every 3 weeks, 10 mg/kg every 2 weeks, 10 mg/kg every 3 weeks, or 200 mg every 3 weeks. An additional study involving 496 patients with stage III melanoma treated with 200 mg adjuvant pembrolizumab every 3 weeks after complete resection was analyzed separately. Of 3655 patients, 2000 were evaluable for immunogenicity analysis, 36 (1.8%) were treatment-emergent (TE) ADA-positive; 9 (0.5%) of these TE-positive patients had antibodies with neutralizing capacity. The presence of pembrolizumab-specific ADAs did not impact pembrolizumab exposure, nor did pembrolizumab immunogenicity affect the incidence of drug-related adverse events (AEs) or infusion-related reactions. There was no clear relationship between the presence of pembrolizumab-specific ADAs and changes in tumor size across treatment regimens. Of the 496 patients treated with pembrolizumab as adjuvant therapy, 495 were evaluable, 17 (3.4%) were TE ADA–positive; none had neutralizing antibodies. The incidence of TE (neutralizing positive) ADAs against pembrolizumab was low in patients with advanced tumors. Furthermore, immunogenicity did not appear to have any clinically relevant effects on the exposure, safety, or efficacy of pembrolizumab. ClinicalTrials.gov, NCT01295827 (February 15, 2011), NCT01704287 (October 11, 2012), NCT01866319 (May 31, 2013), NCT01905657 (July 23, 2013), NCT02142738 (May 20, 2014), NCT01848834 (May 8, 2013), NCT02255097 (October 2, 2014), NCT02460198 (June 2, 2015), NCT01953692 (October 1, 2013), NCT02453594 (May 25, 2015), NCT02256436 (October 3, 2014), NCT02335424 (January 9, 2015), NCT02362594 (February 13, 2015).

Relebactam (REL [MK-7655]) is a novel class A/C β-lactamase inhibitor intended for use with imipenem for the treatment of Gram-negative bacterial infections. REL restores imipenem activity against some resistant strains of Klebsiella and Pseudomonas . In this multicenter, double-blind, controlled trial (NCT01506271), subjects who were ≥18 years of age with complicated intra-abdominal infection were randomly assigned (1:1:1) to receive 250 mg REL, 125 mg REL, or placebo, each given intravenously (i.v.) with 500 mg imipenem-cilastatin (IMI) every 6 h (q6h) for 4 to 14 days. The primary efficacy endpoint was the proportion of microbiologically evaluable (ME) subjects with a favorable clinical response at discontinuation of i.v. therapy (DCIV). A total of 351 subjects were randomized, 347 (99%) were treated, and 255 (73%) were ME at DCIV (55% male; mean age, 49 years). The most common diagnoses were complicated appendicitis (53%) and complicated cholecystitis (17%). Thirty-six subjects (13%) had imipenem-resistant Gram-negative infections at baseline. Both REL doses plus IMI were generally well tolerated and demonstrated safety profiles similar to that of IMI alone. Clinical response rates at DCIV were similar in subjects who received 250 mg REL plus IMI (96.3%) or 125 mg REL plus IMI (98.8%), and both were noninferior to IMI alone (95.2%; one-sided P < 0.001). The treatment groups were also similar with respect to clinical response at early and late follow-up and microbiological response at all visits. Pharmacokinetic/pharmacodynamic simulations show that imipenem exposure at the proposed dose of 500 mg IMI with 250 mg REL q6h provides coverage of >90% of carbapenem-resistant bacterial strains.

Aims Several clinical trials have confirmed the therapeutic benefit of imipenem for treatment of lung infections. There is however no knowledge of the penetration of imipenem into the lung epithelial lining fluid (ELF), the site of action relevant for lung infections. Furthermore, although the plasma pharmacokinetics (PK) of imipenem has been widely studied, most studies have been based on selected patient groups. The aim of this analysis was to characterize imipenem plasma PK across populations and to quantify imipenem ELF penetration. Methods A population model for imipenem plasma PK was developed using data obtained from healthy volunteers, elderly subjects and subjects with renal impairment, in order to identify predictors for inter-individual variability (IIV) of imipenem PK. Subsequently, a clinical study which measured plasma and ELF concentrations of imipenem was included in order to quantify lung penetration. Results A two compartmental model best described the plasma PK of imipenem. Creatinine clearance and body weight were included as subject characteristics predictive for IIV on clearance. Typical estimates for clearance, central and peripheral volume, and inter-compartmental clearance were 11.5 l h–1, 9.37 l, 6.41 l, 13.7 l h–1, respectively (relative standard error (RSE)

Background: Pembrolizumab is approved globally in multiple cancer indications at a dose of 200 mg or 2 mg/kg every three weeks (Q3W). An alternative dosing regimen of 400 mg every six weeks (Q6W), which provides convenience and flexibility to patients and prescribers, is also approved in markets including the European Union (EU), Australia and New Zealand based on pharmacokinetic (PK) modeling and simulation. KEYNOTE-555 Cohort B is an open-label, clinical study in patients with metastatic melanoma designed evaluate the Q6W dosing. The preliminary PK data to validate the model-based assessments as well as efficacy and safety of the Q6W regimen compared to historical data will be described. Methods: A total of 101 patients are enrolled in this study; complete cycle 1 PK data from 37 patients are available. Observed concentration-time profiles from cycle 1 were compared with predictions from the model, which is based on 2993 patients from 5 clinical trials across tumor types. The associated efficacy and safety from these patients will be reviewed and compared to previous clinical trials in advanced melanoma. Results: The demographics from KN-555 Cohort B were similar to previous trials of pembrolizumab in metastatic melanoma, with mean age: 62 years, mean body weight: 85 kg, and 34% female patients. The observed concentrations for 400 mg Q6W were well within the 90% prediction intervals of simulated concentrations using the model. The geometric mean (GM) of observed trough concentration at six weeks (Ctrough) at 400 mg Q6W is 14.5 ug/mL, which is 18% lower than at 200 mg Q3W (18.1 ug/mL) and 11% higher than at 2 mg/kg Q3W (13.4 ug/mL). The GM of observed peak concentration at the end of infusion at 400 mg Q6W is 136 ug/mL, which is below (38% lower) that at the highest clinically tested dose of 10 mg/kg Q2W (220 ug/mL). The ORR in KN-555 Cohort B is comparable to the ORR in previous pembrolizumab studies in metastatic melanoma, indicating similarity of efficacy between the Q6W and Q3W regimens. The safety of the Q6W regimen is comparable to the extensive pembrolizumab safety profile that has been demonstrated in over twelve tumor types. Conclusion: The preliminary PK, efficacy and safety analyzed from KN-555 Cohort B validates the findings from the model-based assessment, of a consistent benefit-risk profile for a 400 mg Q6W regimen as compared to the 200 mg (or 2 mg/kg) Q3W regimen. The study supports that pembrolizumab Q6W is a safe and effective dosing regimen and offers a more convenient option for patients and physicians. Citation Format: Mallika Lala, Omobolaji Akala, Elliot Chartash, Mizuho Kalabis, Shu-Chih Su, Dinesh de Alwis, Vikram Sinha, Lokesh Jain. Pembrolizumab 400 mg Q6W dosing: First clinical outcomes data from Keynote-555 cohort B in metastatic melanoma patients [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr CT042.

3062Background: Pembrolizumab is currently approved for use in multiple cancer indications at a dose of either 200 mg or 2 mg/kg Q3W. An alternative extended dosing regimen would provide convenienc...

Several clinical trials have confirmed the therapeutic benefit of imipenem for treatment of lung infections. There is however no knowledge of the penetration of imipenem into the lung epithelial lining fluid (ELF), the site of action relevant for lung infections. Furthermore, although the plasma pharmacokinetics (PK) of imipenem has been widely studied, most studies have been based on selected patient groups. The aim of this analysis was to characterize imipenem plasma PK across populations and to quantify imipenem ELF penetration.A population model for imipenem plasma PK was developed using data obtained from healthy volunteers, elderly subjects and subjects with renal impairment, in order to identify predictors for inter-individual variability (IIV) of imipenem PK. Subsequently, a clinical study which measured plasma and ELF concentrations of imipenem was included in order to quantify lung penetration.A two compartmental model best described the plasma PK of imipenem. Creatinine clearance and body weight were included as subject characteristics predictive for IIV on clearance. Typical estimates for clearance, central and peripheral volume, and inter-compartmental clearance were 11.5 l h(-1) , 9.37 l, 6.41 l, 13.7 l h(-1) , respectively (relative standard error (RSE)8%). The distribution of imipenem into ELF was described using a time-independent penetration coefficient of 0.44 (RSE 14%).The identified lung penetration coefficient confirms the clinical relevance of imipenem for treatment of lung infections, while the population PK model provided insights into predictors of IIV for imipenem PK and may be of relevance to support dose optimization in various subject groups.

BACKGROUND Warfarin dosage regimens using CYP2C9 and VKORC1 polymorphisms have been extensively studied in adults and is included in US Food and Drug Administration-approved warfarin labeling. However, no dosage algorithm is available for pediatric patients. OBJECTIVE To derive a genetics-based pediatric dosge regimen for warfarin, including starting dose and titration scheme. METHODS A model-based approach was developed based on a previously validated warfarin dosage model in adults, with subsequent comparison to pediatric data from pediatric warfarin dose, genotyping, and international normalized ratio (INR) results. The adult model was based on a previously established model from the CROWN (CReating an Optimal Warfarin dosing Nomogram) trial. Pediatric warfarin data were obtained from a study conducted at the Children’s Hospital of Los Angeles with 26 subjects. Variant alleles of CYP2C9 (rs1799853 or *2, and rs1057910 or *3) and the VKORC1 single nucleotide polymorphism (SNP) rs9923231 (−1639 G>A) were assessed, where the rs numbers are reference SNP identification tags assigned by the National Center for Biotechnology Information. RESULTS A pediatric warfarin model was derived using the previously validated model and clinical pharmacology considerations. The model was validated, and clinical trial simulation and stochastic modeling were used to optimize pediatric dosage and titration. The final dosage regimen was optimized based on simulations targeting a high (≥60%) proportion of INRs within the therapeutic range by week 2 of warfarin therapy while minimizing INRs >3.5 or CONCLUSIONS The proposed pediatric warfarin dosage scheme based on individual CYP2C9 (alleles *1,*2,*3) and VKORC1 rs9923231 (-1639 G>A) genotypes may offer improved dosage compared to current treatment strategies, especially in patients with variant CYP2C9 and VKORC1 alleles. This pilot study provides the foundation for a larger prospective evaluation of genetics-based warfarin dosage in pediatric patients.