Phase I pharmacokinetic, safety, and preliminary efficacy study of tiragolumab in combination with atezolizumab in Chinese patients with advanced solid tumors.

PURPOSE: Tiragolumab is an immunoglobulin G1 monoclonal antibody targeting the immune checkpoint T cell immunoreceptor with immunoglobulin and immunoreceptor ITIM domains. Targeting multiple immune pathways may improve anti-tumor responses. The phase I YP42514 study assessed the pharmacokinetics (PK), safety, and preliminary efficacy of tiragolumab plus atezolizumab in Chinese patients with advanced solid tumors. METHODS: Adult patients from mainland China with Eastern Cooperative Oncology Group performance score 0/1, life expectancy of ≥ 12 weeks, and adequate hematologic/end organ function were eligible. Patients received tiragolumab 600 mg and atezolizumab 1200 mg intravenous every 3 weeks. Key endpoints were PK (serum concentrations of tiragolumab and atezolizumab) and safety. Results from this study were compared with the global phase I study, GO30103 (NCT02794571). RESULTS: In this study, 20 patients received a median of five doses of tiragolumab plus atezolizumab. Median age was 57.5 years, 85.0% of patients were male and the most common tumor type was non-small cell lung cancer. Exposures in Chinese patients were comparable to the global GO30103 population: geometric mean ratio was 1.07 for Cycle 1 tiragolumab area under the concentration-time curve0-21 and 0.92 and 0.93 for Cycle 1 peak and trough atezolizumab exposure, respectively. Treatment-related adverse events were consistent across the Chinese and global populations. Two patients (10.0%) in this study achieved a partial response. CONCLUSION: In this study, tiragolumab plus atezolizumab was tolerable and demonstrated preliminary anti-tumor activity. There were no meaningful differences in the PK or safety of tiragolumab plus atezolizumab between the Chinese and global populations. CLINICAL TRIAL REGISTRATION NUMBER: China Clinical Trial Registry Identifier CTR20210219/YP42514. Date of registration 16 March 2021.

Pharmacokinetics (PK) of Tiragolumab in First-in-Human Study in Patients with Mixed Solid Tumors (GO30103).

Tiragolumab is a first-in-class, fully human IgG1/kappa anti-TIGIT monoclonal antibody that blocks the binding of TIGIT to CD155 (the poliovirus receptor). We summarize the pharmacokinetics (PK) data from the phase 1a/1b GO30103 study of Q3W (every 3 weeks) sequential dosing of tiragolumab (2, 8, 30, 100, 400, 600, or 1200 mg) followed by atezolizumab (1200 mg), Q4W (every 4 weeks) sequential dosing (tiragolumab 840 mg followed by atezolizumab 1680 mg), and Q4W co-infusion (tiragolumab 840 mg plus atezolizumab 1680 mg). Serum samples were collected at multiple time points following tiragolumab and atezolizumab intravenous infusion in patients with solid tumors for PK and immunogenicity assessment. The serum PK profile of tiragolumab appeared to be biphasic, with a rapid distribution phase followed by a slower elimination phase when administered alone or in combination with atezolizumab. In phase 1a, across doses of tiragolumab ranging from 2 to 1200 mg (cycle 1), the geometric mean (GM), coefficient of variation (CV%), serum tiragolumab Cmax ranged from 0.682 to 270 µg/mL (18.6% to 36.5%) and Cmin ranged from 0.0125 to 75.3 µg/mL (0.0% to 24.2%). The GM systemic exposure (area under the plasma drug concentration-time curve, AUC0-21) ranged from 310 to 2670 µg day/mL (20.5% to 27.0%); interindividual variability in AUC0-21 ranged from 20.5% to 43.9%. Tiragolumab exposure increased in an approximately dose-proportional manner when administered alone or with atezolizumab at doses ≥100 mg. Postbaseline, 4/207 patients (1.9%) were positive for treatment-emergent antidrug antibodies (ADA) against tiragolumab, each at a single time point. Tiragolumab combined with atezolizumab demonstrated desirable PK properties, with no drug-drug interactions or immunogenicity liability. There were no meaningful differences in tiragolumab or atezolizumab exposure between the Q4W co-infusion and sequential dosing cohorts. ClinicalTrials.gov: NCT02794571 (date of registration June 6, 2016).

Applying Natural Language Processing to ClinicalTrials.gov: mRNA cancer vaccine case study.

Recently, biotechnology and pharmaceutical industries have made strides to adopt and implement Natural Language Processing (NLP) to address challenges faced when extracting and synthesizing high volumes of information found in unstructured and semistructured text. Here we present, and provide a summary of the findings from, a use case where NLP and text mining methodologies were used to extract clinical trial data from ClinicalTrials.gov for mRNA cancer vaccines.

Atezolizumab plus Magrolimab, Niraparib, or Tocilizumab versus Atezolizumab Monotherapy in Platinum-Refractory Metastatic Urothelial Carcinoma: A Phase Ib/II Open-Label, Multicenter, Randomized Umbrella Study (MORPHEUS Urothelial Carcinoma).

PURPOSE: The MORPHEUS platform was designed to identify early efficacy signals and evaluate the safety of novel immunotherapy combinations across cancer types. The phase Ib/II MORPHEUS-UC trial (NCT03869190) is evaluating atezolizumab plus magrolimab, niraparib, or tocilizumab in platinum-refractory locally advanced or metastatic urothelial carcinoma (mUC). Additional treatment combinations were evaluated and will be reported separately. PATIENTS AND METHODS: Patients had locally advanced or mUC that progressed during or following treatment with a platinum-containing regimen. The primary efficacy endpoint was investigator-assessed objective response rate (ORR). Key secondary endpoints included investigator-assessed progression-free survival (PFS) and overall survival (OS). Safety and exploratory biomarker analyses were also conducted. RESULTS: Seventy-six patients were randomized to receive either atezolizumab plus magrolimab (n = 16), atezolizumab plus niraparib (n = 15), atezolizumab plus tocilizumab (n = 15), or atezolizumab monotherapy (control; n = 30). No additive benefit in ORR, PFS, or OS was seen in the treatment arms versus the control. The best confirmed ORR was 26.7% with atezolizumab plus magrolimab, 6.7% with atezolizumab plus niraparib, 20.0% with atezolizumab plus tocilizumab, and 27.6% with atezolizumab monotherapy. Overall, the treatment combinations were tolerable, and adverse events were consistent with each agent's known safety profile. Trends were observed for shrinkage of programmed death-ligand 1-positive tumors (atezolizumab, atezolizumab plus magrolimab, atezolizumab plus tocilizumab), inflamed tumors, or tumors with high mutational burden (atezolizumab), and immune excluded tumors (atezolizumab plus magrolimab). CONCLUSIONS: The evaluated regimens in MORPHEUS-UC were tolerable. However, response rates for the combinations did not meet the criteria for further development in platinum-experienced locally advanced or mUC.

Early Decision Making in a Randomized Phase II Trial of Atezolizumab in Biliary Tract Cancer Using a Tumor Growth Inhibition-Survival Modeling Framework.

We assess the longitudinal tumor growth inhibition (TGI) metrics and overall survival (OS) predictions applied to patients with advanced biliary tract cancer (BTC) enrolled in IMbrave151 a multicenter randomized phase II, double-blind, placebo-controlled trial evaluating the efficacy and safety of atezolizumab with or without bevacizumab in combination with cisplatin plus gemcitabine. Tumor growth rate (KG) was estimated for patients in IMbrave151. A pre-existing TGI-OS model for patients with hepatocellular carcinoma in IMbrave150 was modified to include available IMbrave151 study covariates and KG estimates and used to simulate IMbrave151 study outcomes. At the interim progression-free survival (PFS) analysis (98 patients, 27 weeks follow-up), clear separation in tumor dynamic profiles with a faster shrinkage rate and slower KG (0.0103 vs. 0.0117 week-1 ; tumor doubling time 67 vs. 59 weeks; KG geometric mean ratio of 0.84) favoring the bevacizumab containing arm was observed. At the first interim analysis for PFS, the simulated OS hazard ratio (HR) 95% prediction interval (PI) of 0.74 (95% PI: 0.58-0.94) offered an early prediction of treatment benefit later confirmed at the final analysis, observed HR of 0.76 based on 159 treated patients and 34 weeks of follow-up. This is the first prospective application of a TGI-OS modeling framework supporting gating of a phase III trial. The findings demonstrate the utility for longitudinal TGI and KG geometric mean ratio as relevant end points in oncology studies to support go/no-go decision making and facilitate interpretation of the IMbrave151 results to support future development efforts for novel therapeutics for patients with advanced BTC.

Atezolizumab Plus PEGPH20 Versus Chemotherapy in Advanced Pancreatic Ductal Adenocarcinoma and Gastric Cancer: MORPHEUS Phase Ib/II Umbrella Randomized Study Platform.

BACKGROUND: The MORPHEUS platform comprises multiple open-label, randomized, phase Ib/II trials designed to identify early efficacy and safety signals of treatment combinations across cancers. Atezolizumab (anti-programmed cell death 1 ligand 1 [PD-L1]) was evaluated in combination with PEGylated recombinant human hyaluronidase (PEGPH20). METHODS: In 2 randomized MORPHEUS trials, eligible patients with advanced, previously treated pancreatic ductal adenocarcinoma (PDAC) or gastric cancer (GC) received atezolizumab plus PEGPH20, or control treatment (mFOLFOX6 or gemcitabine plus nab-paclitaxel [MORPHEUS-PDAC]; ramucirumab plus paclitaxel [MORPHEUS-GC]). Primary endpoints were objective response rates (ORR) per RECIST 1.1 and safety. RESULTS: In MORPHEUS-PDAC, ORRs with atezolizumab plus PEGPH20 (n = 66) were 6.1% (95% CI, 1.68%-14.80%) vs. 2.4% (95% CI, 0.06%-12.57%) with chemotherapy (n = 42). In the respective arms, 65.2% and 61.9% had grade 3/4 adverse events (AEs); 4.5% and 2.4% had grade 5 AEs. In MORPHEUS-GC, confirmed ORRs with atezolizumab plus PEGPH20 (n = 13) were 0% (95% CI, 0%-24.7%) vs. 16.7% (95% CI, 2.1%-48.4%) with control (n = 12). Grade 3/4 AEs occurred in 30.8% and 75.0% of patients, respectively; no grade 5 AEs occurred. CONCLUSION: Atezolizumab plus PEGPH20 showed limited clinical activity in patients with PDAC and none in patients with GC. The safety of atezolizumab plus PEGPH20 was consistent with each agent's known safety profile. (ClinicalTrials.gov Identifier: NCT03193190 and NCT03281369).

Development of a pediatric physiologically-based pharmacokinetic model to support recommended dosing of atezolizumab in children with solid tumors.

Background: Atezolizumab has been studied in multiple indications for both pediatric and adult patient populations. Generally, clinical studies enrolling pediatric patients may not collect sufficient pharmacokinetic data to characterize the drug exposure and disposition because of operational, ethical, and logistical challenges including burden to children and blood sample volume limitations. Therefore, mechanistic modeling and simulation may serve as a tool to predict and understand the drug exposure in pediatric patients. Objective: To use mechanistic physiologically-based pharmacokinetic (PBPK) modeling to predict atezolizumab exposure at a dose of 15 mg/kg (max 1,200 mg) in pediatric patients to support dose rationalization and label recommendations. Methods: A minimal mechanistic PBPK model was used which incorporated age-dependent changes in physiology and biochemistry that are related to atezolizumab disposition such as endogenous IgG concentration and lymph flow. The PBPK model was developed using both in vitro data and clinically observed data in adults and was verified across dose levels obtained from a phase I and multiple phase III studies in both pediatric patients and adults. The verified model was then used to generate PK predictions for pediatric and adult subjects ranging from 2- to 29-year-old. Results: Individualized verification in children and in adults showed that the simulated concentrations of atezolizumab were comparable (76% within two-fold and 90% within three-fold, respectively) to the observed data with no bias for either over- or under-prediction. Applying the verified model, the predicted exposure metrics including Cmin, Cmax, and AUCtau were consistent between pediatric and adult patients with a geometric mean of pediatric exposure metrics between 0.8- to 1.25-fold of the values in adults. Conclusion: The results show that a 15 mg/kg (max 1,200 mg) atezolizumab dose administered intravenously in pediatric patients provides comparable atezolizumab exposure to a dose of 1,200 mg in adults. This suggests that a dose of 15 mg/kg will provide adequate and effective atezolizumab exposure in pediatric patients from 2- to 18-year-old.

Atezolizumab and Bevacizumab in Patients with Unresectable Hepatocellular Carcinoma: Pharmacokinetic and Safety Assessments Based on Hepatic Impairment Status and Geographic Region.

INTRODUCTION: Phase 1b GO30140 and phase 3 IMbrave150 studies evaluated first-line atezolizumab + bevacizumab for unresectable hepatocellular carcinoma (HCC). Here, we evaluated pharmacokinetics (PK) and safety by hepatic impairment status and geographic region. METHODS: Patients received atezolizumab 1,200 mg + bevacizumab 15 mg/kg IV every 3 weeks. Drug concentrations were evaluated by descriptive statistics and population PK. PK and adverse event frequencies were evaluated by hepatic impairment status and region. RESULTS: 323 IMbrave150 patients and 162 GO30140 patients were PK evaluable. Compared with IMbrave150 patients who had normal hepatic function per the National Cancer Institute Organ Dysfunction Working Group (NCI-ODWG) criteria (n = 123), patients with mild impairment (n = 171) had a geometric mean ratio (GMR) of 0.92 for cycle 1 atezolizumab area under the concentration-time curve (AUC); patients with moderate impairment (n = 27) had a GMR of 0.88. Patients in Asia ([n = 162] vs. outside [n = 161]) had a GMR of 1.25 for cycle 1 atezolizumab AUC. Compared with GO30140 patients who had normal hepatic function (NCI-ODWG [n = 61]), patients with mild impairment (n = 92) had a GMR of 0.97 for cycle 1 peak bevacizumab concentrations; those with moderate impairment (n = 9) had a GMR of 0.94. Patients in Asia (n = 111) versus outside Asia (n = 51) had a GMR of 0.94 for cycle 1 peak bevacizumab concentration. PK results were generally comparable when evaluated based on additional hepatic functional definitions (Child-Pugh or albumin/bilirubin criteria) or study enrollment in Japan. No associations between atezolizumab PK and HCC etiology were seen. Adverse event frequencies were similar across evaluated groups. CONCLUSIONS: IMbrave150 and GO30140 patients with unresectable HCC had varying baseline hepatic impairment and high enrollment from Asia. PK data demonstrated considerable exposure overlap across groups. Treatment was tolerable across groups. No need for dose adjustment based on mild or moderate hepatic impairment or region is recommended based on this analysis.

Pharmacology-based ranking of anti-cancer drugs to guide clinical development of cancer immunotherapy combinations.

The success of antibodies targeting Programmed cell death protein 1 (PD-1) and its ligand L1 (PD-L1) in cancer treatment and the need for improving response rates has led to an increased demand for the development of combination therapies with anti-PD-1/PD-L1 blockers as a backbone. As more and more drugs with translational potential are identified, the number of clinical trials evaluating combinations has increased considerably and the demand to prioritize combinations having potential for success over the ones that are unlikely to be successful is rising. This review aims to address the unmet need to prioritize cancer immunotherapy combinations through comprehensive search of potential drugs and ranking them based on their mechanism of action, clinical efficacy and safety. As lung cancer is one of the most frequently studied cancer types, combinations that showed potential for the treatment of lung cancer were prioritized. A literature search was performed to identify drugs with potential in combination with PD-1/PD-L1 blockers and the drugs were ranked based on their mechanism of action and known clinical efficacy. Nineteen drugs or drug classes were identified from an internal list of lead molecules and were scored for their clinical potential. Efficacy and safety data from pivotal studies was summarized for the selected drugs. Further, overlap of mechanisms of action and adverse events was visualized using a heat map illustration to help screen drugs for combinations. The quantitative scoring methodology provided in this review could serve as a template for preliminary ranking of novel combinations.

Personalized Cancer Vaccines: Clinical Landscape, Challenges, and Opportunities.

Tremendous innovation is underway among a rapidly expanding repertoire of promising personalized immune-based treatments. Therapeutic cancer vaccines (TCVs) are attractive systemic immunotherapies that activate and expand antigen-specific CD8+ and CD4+ T cells to enhance anti-tumor immunity. Our review highlights key issues impacting TCVs in clinical practice and reports on progress in development. We review the mechanism of action, immune-monitoring, dosing strategies, combinations, obstacles, and regulation of cancer vaccines. Most trials of personalized TCVs are ongoing and represent diverse platforms with predominantly early investigations of mRNA, DNA, or peptide-based targeting strategies against neoantigens in solid tumors, with many in combination immunotherapies. Multiple delivery systems, routes of administration, and dosing strategies are used. Intravenous or intramuscular administration is common, including delivery by lipid nanoparticles. Absorption and biodistribution impact antigen uptake, expression, and presentation, affecting the strength, speed, and duration of immune response. The emerging trials illustrate the complexity of developing this class of innovative immunotherapies. Methodical testing of the multiple potential factors influencing immune responses, as well as refined quantitative methodologies to facilitate optimal dosing strategies, could help resolve uncertainty of therapeutic approaches. To increase the likelihood of success in bringing these medicines to patients, several unique development challenges must be overcome.

Application of a Two-Analyte Integrated Population Pharmacokinetic Model to Evaluate the Impact of Intrinsic and Extrinsic Factors on the Pharmacokinetics of Polatuzumab Vedotin in Patients with Non-Hodgkin Lymphoma.

PURPOSE: The established two-analyte integrated population pharmacokinetic model was applied to assess the impact of intrinsic/extrinsic factors on the pharmacokinetics (PK) of polatuzumab vedotin (pola) in patients with non-Hodgkin lymphoma (NHL) following bodyweight-based dosing. METHODS: Model simulations based on individual empirical Bayes estimates were used to evaluate the impact of intrinsic/extrinsic factors as patient subgroups on Cycle 6 exposures. Intrinsic factors included bodyweight, age, sex, hepatic and renal functions. Extrinsic factors included rituximab/obinutuzumab or bendamustine combination with pola and manufacturing process. The predicted impact on exposures along with the established exposure-response relationships were used to assess clinical relevance. RESULTS: No clinically meaningful differences in Cycle 6 pola exposures were found for the following subgroups: bodyweight 100-146 kg versus 38-<100 kg, age ≥ 65 years versus <65 years, female versus male, mild hepatic impairment versus normal, mild-to-moderate renal impairment versus normal. Co-administration of rituximab/obinutuzumab or bendamustine, and change in the pola manufacturing process, also had no meaningful impact on PK. CONCLUSIONS: In patients with NHL, bodyweight-based dosing is adequate, and no further dose adjustment is recommended for the heavier subgroup (100-146 kg). In addition, no dose adjustments are recommended for other subgroups based on intrinsic/extrinsic factors evaluated.

Pan-cancer population pharmacokinetics and exposure-safety and -efficacy analyses of atezolizumab in patients with high tumor mutational burden.

We retrospectively investigated the pharmacokinetics and exposure-efficacy/safety relationships of single-agent atezolizumab based on tissue tumor mutational burden (tTMB) status (high vs low [≥16 vs <16 mutations/megabase]) in a pan-tumor population from seven clinical trials. Data sources included the OAK, POPLAR, BIRCH, FIR, IMvigor210, IMvigor211, and PCD4989g studies; 986 of 2894 treated patients (34%) had TMB data. Exposure metrics were obtained using a prior two-compartment intravenous-infusion population-pharmacokinetics model, merged with prognostic, biomarker, efficacy, and safety variables. Baseline demographic/clinical characteristics and prognostic factors were well balanced between patients with high (n = 175) and low (n = 811) tTMB. Exposure was similar in the high- and low-tTMB subgroups, with no difference seen in the evaluable vs total treated populations. The objective response rate (ORR) was 29.7% vs 13.4%, complete response rate was 6.9% vs 3.2%, and median duration of response (95% CI) was 29.0 (18.6-NE) months vs 15.9 (12.5-20.5) months for patients with high-tTMB vs low-tTMB tumors, respectively. A flat exposure-efficacy relationship was seen for ORR in patients with high-tTMB based on the cycle 1 minimum atezolizumab concentration and area under the serum concentration time curve (AUC). A nonsignificant exposure-safety profile was seen for grade 3/4 adverse events and adverse events of special interest based on the AUC of atezolizumab in the high-tTMB population. tTMB is an additional predictive biological factor affecting response to atezolizumab, and quantitative investigations of atezolizumab exposure and relationships of exposure with safety and efficacy support the use of a 1200-mg, every 3-week regimen in a tumor-agnostic high-tTMB population.

Pharmacokinetics of polatuzumab vedotin in combination with R/G-CHP in patients with B-cell non-Hodgkin lymphoma.

PURPOSE: The phase Ib/II open-label study (NCT01992653) evaluated the antibody-drug conjugate polatuzumab vedotin (pola) plus rituximab/obinutuzumab, cyclophosphamide, doxorubicin, and prednisone (R/G-CHP) as first-line therapy for B-cell non-Hodgkin lymphoma (B-NHL). We report the pharmacokinetics (PK) and drug-drug interaction (DDI) for pola. METHODS: Six or eight cycles of pola 1.0-1.8 mg/kg were administered intravenously every 3 weeks (q3w) with R/G-CHP. Exposures of pola [including antibody-conjugated monomethyl auristatin E (acMMAE) and unconjugated MMAE] and R/G-CHP were assessed by non-compartmental analysis and/or descriptive statistics with cross-cycle comparisons to cycle 1 and/or after multiple cycles. Pola was evaluated as a potential victim and perpetrator of a PK drug-drug interaction with R/G-CHP. Population PK (popPK) analysis assessed the impact of prior treatment status (naïve vs. relapsed/refractory) on pola PK. RESULTS: Pola PK was similar between treatment arms and independent of line of therapy. Pola PK was dose proportional from 1.0 to 1.8 mg/kg with R/G-CHP. Geometric mean volume of distribution and clearance of acMMAE ranged from 57.3 to 95.6 mL/kg and 12.7 to 18.2 mL/kg/day, respectively. acMMAE exhibited multi-exponential decay (elimination half-life ~ 1 week). Unconjugated MMAE exhibited formation rate-limited kinetics. Exposures of pola with R/G-CHP were similar to those in the absence of CHP; exposures of R/G-CHP in the presence of pola were comparable to those in the absence of pola. CONCLUSIONS: Pola PK was well characterized with no clinically meaningful DDIs with R/G-CHP. Findings are consistent with previous studies of pola + R/G, and support pola + R/G-CHP use in previously untreated diffuse large B-cell lymphoma.

Integrated Two-Analyte Population Pharmacokinetic Model of Polatuzumab Vedotin in Patients With Non-Hodgkin Lymphoma.

A two-analyte integrated population pharmacokinetic (PK) model that simultaneously describes concentrations of antibody-conjugated monomethyl auristatin E (acMMAE) and unconjugated MMAE following repeated administrations of polatuzumab vedotin (pola) was developed based on data from four clinical studies of pola in patients with non-Hodgkin lymphoma. A two-compartment model with a nonspecific, time-dependent linear clearance, a linear time-dependent exponentially declining clearance, and a Michaelis-Menten clearance provided a good fit of the acMMAE plasma PK profiles. All three acMMAE elimination pathways contributed to the input to the central compartment of unconjugated MMAE, which was also described by a two-compartment model. Population PK parameters, covariate effects, and interindividual variability of model parameters were estimated. The impact of clinically relevant covariates on PK exposures of each analyte were quantified and reported to support key label claims.

Atezolizumab for children and young adults with previously treated solid tumours, non-Hodgkin lymphoma, and Hodgkin lymphoma (iMATRIX): a multicentre phase 1-2 study.

BACKGROUND: Atezolizumab is an inhibitor of PD-L1, which can lead to enhanced anticancer T-cell activity. We aimed to evaluate the safety, pharmacokinetics, and activity of atezolizumab in children and young adults with refractory or relapsed solid tumours, with known or expected PD-L1 expression. METHODS: iMATRIX was a multicentre, open-label, phase 1-2 trial of patients (aged <30 years) with solid tumours or lymphomas recruited from 28 hospitals in ten countries (USA, France, Italy, UK, Spain, the Netherlands, Denmark, Israel, Switzerland, and Germany). Eligible patients younger than 18 years received 15 mg/kg atezolizumab (maximum 1200 mg); patients aged 18-29 years received the adult dose (1200 mg) until disease progression or loss of clinical benefit. Co-primary endpoints were safety (assessed by incidence of adverse events) and pharmacokinetics (assessed by serum atezolizumab concentrations). Secondary endpoints included the proportion of patients achieving an objective response. This trial is registered with ClinicalTrials.gov, number NCT02541604. FINDINGS: Between Nov 5, 2015, and April 2, 2018, we screened 115 patients, 25 of whom did not meet the inclusion criteria. 90 patients, with a median age of 14 years (IQR 10-17), were enrolled. At the data cutoff (April 2, 2018), two patients remained on study treatment. 87 (97%) of 90 patients received at least one dose of atezolizumab at 15 mg/kg or 1200 mg and were evaluable for safety. Three patients were not treated owing to either poor clinical condition or withdrawal of consent. In the safety-evaluable population (n=87), the most common adverse events were pyrexia (36 [41%] patients) and fatigue (31 [36%]). The most common grade 3-4 adverse event was anaemia (19 [22%] patients). The most commonly reported serious adverse events were in the categories of infections and infestations; pyrexia was the only serious adverse event reported in more than two patients. 57 (66%) patients had at least one treatment-related adverse event (grade 1-4); fatigue was the most common treatment-related adverse event (17 patients [20%]). There were no fatal adverse events. Mean serum concentrations of atezolizumab were overlapping and comparable between children receiving 15 mg/kg and young adults receiving 1200 mg of atezolizumab every 3 weeks. Serum concentrations of atezolizumab were above the target exposure level in all patients. At 6 months, four patients (5%) achieved an objective response (all partial responses). INTERPRETATION: Although response to atezolizumab was restricted, atezolizumab was well tolerated with generally comparable exposure across populations. Our findings might help to define future development strategies for immune checkpoint inhibitors either by focusing research to specific disease subpopulations that exhibit greater benefit from immune checkpoint inhibitors, or by providing the means to identify therapeutic combination partners that augment T-cell infiltration and proliferation in so-called immune cold tumour microenvironments. FUNDING: F Hoffmann-La Roche.

Population pharmacokinetics, exposure-safety, and immunogenicity of atezolizumab in pediatric and young adult patients with cancer.

BACKGROUND: The iMATRIX-atezolizumab study was a phase I/II, multicenter, open-label study designed to assess the safety and pharmacokinetics of atezolizumab in pediatric and young adult patients. We describe the pharmacokinetics (PK), exposure-safety, and immunogenicity of atezolizumab in pediatric and young adults with metastatic solid tumors or hematologic malignancies enrolled in this study. METHODS: Patients aged < 18 years (n = 69) received a weight-adjusted dose of atezolizumab (15 mg/kg every 3 weeks [q3w]; maximum 1200 mg); those aged ≥ 18 years (n = 18) received a flat dose (1200 mg q3w). A prior two-compartment intravenous infusion input adult population-PK (popPK) model of atezolizumab was used as a basis to model pediatric data. RESULTS: A total of 431 atezolizumab serum concentrations from 87 relapse-refractory pediatric and young adult patients enrolled in the iMATRIX-atezolizumab study were used for the popPK analysis. The dataset comprised predominantly patients aged < 18 years, including two infants aged < 2 years, with a wide body weight and age range. The clearance and volume of distribution estimates of atezolizumab were 0.217 L/day and 3.01 L, respectively. Atezolizumab geometric mean trough exposures were ~ 20% lower in pediatric patients versus young adults; this was not clinically meaningful as both groups achieved the target concentration (6 µg/mL). Safety was similar between pediatric and young adult patients with no exposure-safety relationship observed. Limited responses (4/87) precluded an exposure-response assessment on outcomes. A comparable rate (13% vs 11%) of atezolizumab anti-drug antibodies was seen in pediatric and young adult patients. CONCLUSIONS: These findings demonstrate a similar exposure-safety profile of atezolizumab in pediatric and young adult patients, supportive of weight-based dosing in pediatric patients. TRIAL REGISTRATION: NCT02541604.

Assessment of the Drug Interaction Potential of Unconjugated and GalNAc3-Conjugated 2'-MOE-ASOs.

Antisense oligonucleotides are metabolized by nucleases and drug interactions with small drug molecules at either the cytochrome P450 (CYP) enzyme or transporter levels have not been observed to date. Herein, a comprehensive in vitro assessment of the drug-drug interaction (DDI) potential was carried out with four 2'-O-(2-methoxyethyl)-modified antisense oligonucleotides (2'-MOE-ASOs), including a single triantennary N-acetyl galactosamine (GalNAc3)-conjugated ASO. Several investigations to describe the DDI potential of a 2'-MOE-ASO conjugated to a high-affinity ligand for hepatocyte-specific asialoglycoprotein receptors are explored. The inhibition on CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP2E1, and CYP3A4 and induction on CYP1A2, CYP2B6, and CYP3A4 were investigated in cryopreserved hepatocytes using up to 100 µM of each ASO. No significant inhibition (half maximal inhibitory concentration [IC50] > 100 µM) or induction was observed based on either enzymatic phenotype or mRNA levels. In addition, transporter interaction studies were conducted with nine major transporters per recommendations from regulatory guidances and included three hepatic uptake transporters, organic cation transporter 1 (OCT1), organic anion transporting polypeptide 1B1 (OATP1B1), and OATP1B3; three renal uptake transporters, organic anion transporter 1 (OAT1), OAT3, and OCT2; and three efflux transporters, P-glycoprotein (P-gp), breast cancer resistance protein (BCRP), and bile salt export pump (BSEP). None of the four ASOs (10 µM) were substrates of any of the nine transporters, with uptake <2-fold compared to controls, and efflux ratios were below 2.0 for BCRP and P-gp. Additionally, neither of the four ASOs showed meaningful inhibition on any of the nine transporters tested, with the mean percent inhibition ranging from -38.3% to 24.2% with 100 µM ASO. Based on these findings, the unconjugated and GalNAc3-conjugated 2'-MOE-ASOs would have no or minimal DDI with small drug molecules via any major CYP enzyme or drug transporters at clinically relevant exposures.

Disposition and Pharmacology of a GalNAc3-conjugated ASO Targeting Human Lipoprotein (a) in Mice.

Triantennary N-acetyl galactosamine (GalNAc3)-conjugated antisense oligonucleotides (ASOs) have greatly improved potency via receptor-mediated uptake. In the present study, the in vivo pharmacology of a 2'-O-(2-methoxyethyl)-modified ASO conjugated with GalNAc3 (ISIS 681257) together with its unmodified congener (ISIS 494372) targeting human apolipoprotein (a) (apo(a)), were studied in human LPA transgenic mice. Further, the disposition kinetics of ISIS 681257 was studied in CD-1 mice. ISIS 681257 demonstrated over 20-fold improvement in potency over ISIS 494372 as measured by liver apo(a) mRNA and plasma apo(a) protein levels. Following subcutaneous (SC) dosing, ISIS 681257 cleared rapidly from plasma and distributed to tissues. Intact ISIS 681257 was the major full-length oligonucleotide species in plasma. In tissues, however, GalNAc sugar moiety was rapidly metabolized and unconjugated ISIS 681257 accounted > 97% of the total exposure, which was then cleared slowly from tissues with a half-life of 7-8 days, similar to the half-life in plasma. ISIS 681257 is highly bound to plasma proteins (> 94% bound), which limited its urinary excretion. This study confirmed dose-dependent exposure to the parent drug ISIS 681257 in plasma and rapid conversion to unconjugated ASO in tissues. Safety data and the extended half-life support its further development and weekly dosing in phase 1 clinical studies.

Elucidation of the Biotransformation Pathways of a Galnac3-conjugated Antisense Oligonucleotide in Rats and Monkeys.

Triantennary N-acetyl galactosamine (GalNAc3) is a high-affinity ligand for hepatocyte-specific asialoglycoprotein receptors. Conjugation with GalNAc3 via a trishexylamino (THA)-C6 cluster significantly enhances antisense oligonucleotide (ASO) potency. Herein, the biotransformation, disposition, and elimination of the THA cluster of ION-681257, a GalNAc3-conjugated ASO currently in clinical development, are investigated in rats and monkey. Rats were administered a single subcutaneous dose of (3)H-radiolabeled ((3)H placed in THA) or nonradiolabeled ION-681257. Mass balance included radiometric profiling and metabolite fractionation with characterization by mass spectrometry. GalNAc3-conjugated ASOs were extensively distributed into liver. The THA-C6 triantenerrary GalNAc3 conjugate at the 5'-end of the ASO was rapidly metabolized and excreted with 25.67 ± 1.635% and 71.66 ± 4.17% of radioactivity recovered in urine and feces within 48 hours postdose. Unchanged drug, short-mer ASOs, and linker metabolites were detected in urine. Collectively, 14 novel linker associated metabolites were discovered including oxidation at each branching arm, initially by monooxidation at the ß-position followed by dioxidation at the α-arm, and lastly, tri and tetra oxidations on the two remaining ß-arms. Metabolites in bile and feces were identical to urine except for oxidized linear and cyclic linker metabolites. Enzymatic reaction phenotyping confirmed involvement of N-acetyl-ß-glucosaminidase, deoxyribonuclease II, alkaline phosphatase, and alcohol + aldehyde dehydrogenases on the complex metabolism pathway for THA supplementing in vivo findings. Lastly, excreta from monkeys treated with ION-681257 revealed the identical series as observed in rat. In summary, our findings provide an improved understanding of GalNAc3-conjugated-ASO metabolism pathways which facilitate similar development programs.

Pharmacokinetic and Pharmacodynamic Investigations of ION-353382, a Model Antisense Oligonucleotide: Using Alpha-2-Macroglobulin and Murinoglobulin Double-Knockout Mice.

To investigate the pharmacokinetics (PKs) and pharmacodynamics (PDs) for ION-353382, an antisense oligonucleotide (ASO) targeting scavenger receptor class B type I (SRB1) mRNA, using alpha-2-macroglobulin (A2M), murinoglobulin double-knockout (DKO), and wild-type mice. Wild-type and DKO homozygous mice were administered a single subcutaneous injection of ION-353382 at 0, 5, 15, 30, and 60 mg/kg. Mice were sacrificed at 72 h with plasma and organs harvested. Both liquid chromatography-mass spectrometry (LC-MS) and enzyme-linked immunosorbent assay (ELISA) were used to determine ASO exposure with real-time PCR for SRB1 expression. Immunohistochemistry was evaluated to explore hepatic uptake of ASOs. The total plasma protein binding and profiling was assessed. Finally, two-dimensional gel electrophoresis identified protein expression differences. PK exposures were comparable between wild-type and DKO mice in plasma, liver, and kidney, yet a near twofold reduction in EC50 was revealed for DKO mice based on an inhibitory effect liver exposure response model. Total plasma protein binding and profiling revealed no major dissimilarities between both groups. Plasma proteome fingerprinting confirmed protein expression variations related to A2M. Histological examination revealed enhanced ASO distribution into hepatocytes and less nonparenchymal uptake for DKO mice compared to wild-type mice. Knocking out A2M showed improved PD activities without an effect on total plasma and tissue exposure kinetics. Binding to A2M could mediate ASOs to nonproductive compartments, and thus, decreased binding of ASOs to A2M could potentially improve ASO pharmacology.