CD19-CD28: an affinity-optimized CD28 agonist for combination with glofitamab (CD20-TCB) as off-the-shelf immunotherapy.

ABSTRACT: Effective T-cell responses not only require the engagement of T-cell receptors (TCRs; "signal 1"), but also the availability of costimulatory signals ("signal 2"). T-cell bispecific antibodies (TCBs) deliver a robust signal 1 by engaging the TCR signaling component CD3ε, while simultaneously binding to tumor antigens. The CD20-TCB glofitamab redirects T cells to CD20-expressing malignant B cells. Although glofitamab exhibits strong single-agent efficacy, adding costimulatory signaling may enhance the depth and durability of T-cell-mediated tumor cell killing. We developed a bispecific CD19-targeted CD28 agonist (CD19-CD28), RG6333, to enhance the efficacy of glofitamab and similar TCBs by delivering signal 2 to tumor-infiltrating T cells. CD19-CD28 distinguishes itself from the superagonistic antibody TGN1412, because its activity requires the simultaneous presence of a TCR signal and CD19 target binding. This is achieved through its engineered format incorporating a mutated Fc region with abolished FcγR and C1q binding, CD28 monovalency, and a moderate CD28 binding affinity. In combination with glofitamab, CD19-CD28 strongly increased T-cell effector functions in ex vivo assays using peripheral blood mononuclear cells and spleen samples derived from patients with lymphoma and enhanced glofitamab-mediated regression of aggressive lymphomas in humanized mice. Notably, the triple combination of glofitamab with CD19-CD28 with the costimulatory 4-1BB agonist, CD19-4-1BBL, offered substantially improved long-term tumor control over glofitamab monotherapy and respective duplet combinations. Our findings highlight CD19-CD28 as a safe and highly efficacious off-the-shelf combination partner for glofitamab, similar TCBs, and other costimulatory agonists. CD19-CD28 is currently in a phase 1 clinical trial in combination with glofitamab. This trial was registered at www.clinicaltrials.gov as #NCT05219513.

Phase I study of daily and weekly regimens of the orally administered MDM2 antagonist idasanutlin in patients with advanced tumors.

Aim The oral MDM2 antagonist idasanutlin inhibits the p53-MDM2 interaction, enabling p53 activation, tumor growth inhibition, and increased survival in xenograft models. Methods We conducted a Phase I study of idasanutlin (microprecipitate bulk powder formulation) to determine the maximum tolerated dose (MTD), safety, pharmacokinetics, pharmacodynamics, food effect, and clinical activity in patients with advanced malignancies. Schedules investigated were once weekly for 3 weeks (QW × 3), once daily for 3 days (QD × 3), or QD × 5 every 28 days. We also analyzed p53 activation and the anti-proliferative effects of idasanutlin. Results The dose-escalation phase included 85 patients (QW × 3, n = 36; QD × 3, n = 15; QD × 5, n = 34). Daily MTD was 3200 mg (QW × 3), 1000 mg (QD × 3), and 500 mg (QD × 5). Most common adverse events were diarrhea, nausea/vomiting, decreased appetite, and thrombocytopenia. Dose-limiting toxicities were nausea/vomiting and myelosuppression; myelosuppression was more frequent with QD dosing and associated with pharmacokinetic exposure. Idasanutlin exposure was approximately dose proportional at low doses, but less than dose proportional at > 600 mg. Although inter-patient variability in exposure was high with all regimens, cumulative idasanutlin exposure over the whole 28-day cycle was greatest with a QD × 5 regimen. No major food effect on pharmacokinetic exposure occurred. MIC-1 levels were higher with QD dosing, increasing in an exposure-dependent manner. Best response was stable disease in 30.6% of patients, prolonged (> 600 days) in 2 patients with sarcoma. Conclusions Idasanutlin demonstrated dose- and schedule-dependent p53 activation with durable disease stabilization in some patients. Based on these findings, the QD × 5 schedule was selected for further development. TRIAL REGISTRATION: NCT01462175 (ClinicalTrials.gov), October 31, 2011.

Safety, pharmacokinetics, and pharmacodynamic activity of obinutuzumab, a type 2 anti-CD20 monoclonal antibody for the desensitization of candidates for renal transplant.

The limited effectiveness of rituximab plus intravenous immunoglobulin (IVIG) in desensitization may be due to incomplete B cell depletion. Obinutuzumab is a type 2 anti-CD20 antibody that induces increased B cell depletion relative to rituximab and may therefore be more effective for desensitization. This open-label phase 1b study assessed the safety, pharmacokinetics, and pharmacodynamics of obinutuzumab in highly sensitized patients with end-stage renal disease. Patients received 1 (day 1, n = 5) or 2 (days 1 and 15; n = 20) infusions of 1000-mg obinutuzumab followed by 2 doses of IVIG on days 22 and 43. Eleven patients received additional obinutuzumab doses at the time of transplant and/or at week 24. The median follow-up duration was 9.4 months. Obinutuzumab was well tolerated, and most adverse events were grade 1-2 in severity. There were 11 serious adverse events (SAEs) in 9 patients (36%); 10 of these SAEs were infections and 4 occurred after kidney transplant. Obinutuzumab plus IVIG resulted in profound peripheral B cell depletion and appeared to reduce B cells in retroperitoneal lymph nodes. Reductions in anti-HLA antibodies, number of unacceptable antigens, and the calculated panel reactive antibody score as centrally assessed using single-antigen bead assay were limited and not clinically meaningful for most patients (NCT02586051).

Pharmacokinetics, exposure, efficacy and safety of obinutuzumab in rituximab-refractory follicular lymphoma patients in the GADOLIN phase III study.

AIMS: Rituximab is standard care in a number of lymphoma subtypes, including follicular lymphoma (FL), although many patients are resistant to rituximab, or develop resistance with repeated treatment, and a high proportion relapse. Obinutuzumab is a novel anti-CD20 monoclonal antibody with improved efficacy over rituximab. It is approved for previously untreated chronic lymphocytic leukaemia (CLL), and for use with bendamustine in patients with rituximab-relapsed/refractory FL. METHODS: Using a previously described population pharmacokinetic (PK) model of obinutuzumab in patients with non-Hodgkin lymphoma and CLL, we conducted an exposure-response analysis using data from 6 clinical trials in patients with CD20+ B-cell malignancies (CLL11, GADOLIN, GATHER, GAUDI, GAUGUIN and GAUSS) to describe the PK properties of obinutuzumab, identify covariates influencing exposure, and explore how exposure affects safety, efficacy and pharmacodynamics. RESULTS: A 2-compartment model with linear and time-dependent clearance described obinutuzumab PK. Disease type and subtype, body weight, baseline tumour size, and sex had the largest effects on PK. Obinutuzumab exposure was not associated with occurrence or severity of adverse events, but higher exposure appeared to be associated with greater efficacy, particularly longer progression-free survival. However, in multivariate Cox regression analysis, progression-free survival benefit in the obinutuzumab plus bendamustine arm was independent of exposure. CONCLUSION: The updated population PK model reported here accurately describes the PK of obinutuzumab patients with non-Hodgkin lymphoma and CLL. The selected obinutuzumab dosing regimen offers clinical benefit in a majority of rituximab-refractory FL patients treated with bendamustine, irrespective of variability in exposure, whilst minimising adverse events.

Role of obinutuzumab exposure on clinical outcome of follicular lymphoma treated with first-line immunochemotherapy.

AIMS: Obinutuzumab (G) is a humanized type II, Fc-glycoengineered anti-CD20 monoclonal antibody used in various indications, including patients with previously untreated front-line follicular lymphoma. We investigated sources of variability in G exposure and association of progression-free survival (PFS) with average concentration over induction (CmeanIND ) in front-line follicular lymphoma patients treated with G plus chemotherapy (bendamustine, CHOP, or CVP) in the GALLIUM trial. METHODS: Individual exposures (CmeanIND ) were obtained from a previously established population pharmacokinetic model updated with GALLIUM data. Multivariate Cox proportional hazard models and univariate Kaplan-Meier plots investigated relationships of PFS with exposure and other potential prognostic factors. RESULTS: Overall, G exposure was lower in high body-weight patients and in males, and slightly lower in patients with high baseline tumour burden. Analysis of clinical outcomes showed that variability in G exposure did not impact PFS in G-bendamustine-treated patients; PFS was inferior in males and patients with FCGR2a/2b T232 T low-affinity receptor variant, and superior in patients with FCGR2a/2b I232T variant. In G-CHOP/CVP arms, PFS improved with increasing CmeanIND (hazard ratio = 1.74 and 0.394 at 5th and 95th percentile compared to median CmeanIND ) and was inferior in patients with high baseline tumour size and B symptoms. CONCLUSIONS: It remains unclear whether for G-CHOP/CVP patients lower G exposure is a consequence of adverse disease biology and/or resistance to chemotherapy backbone (higher clearance in nonresponder patients, as demonstrated for rituximab) rather than being the cause of poorer clinical outcome. A study with >1 dose level of G could help resolve this uncertainty.

Positron emission tomography measurement of brain MAO-B inhibition in patients with Alzheimer's disease and elderly controls after oral administration of sembragiline.

PURPOSE: In Alzheimer's disease (AD), increased metabolism of monoamines by monoamine oxidase type B (MAO-B) leads to the production of toxic reactive oxygen species (ROS), which are thought to contribute to disease pathogenesis. Inhibition of the MAO-B enzyme may restore brain levels of monoaminergic neurotransmitters, reduce the formation of toxic ROS and reduce neuroinflammation (reactive astrocytosis), potentially leading to neuroprotection. Sembragiline (also referred as RO4602522, RG1577 and EVT 302 in previous communications) is a potent, selective and reversible inhibitor of MAO-B developed as a potential treatment for AD. METHODS: This study assessed the relationship between plasma concentration of sembragiline and brain MAO-B inhibition in patients with AD and in healthy elderly control (EC) subjects. Positron emission tomography (PET) scans using [11C]-L-deprenyl-D2 radiotracer were performed in ten patients with AD and six EC subjects, who received sembragiline each day for 6-15 days. RESULTS: At steady state, the relationship between sembragiline plasma concentration and MAO-B inhibition resulted in an Emax of ∼80-90 % across brain regions of interest and in an EC50 of 1-2 ng/mL. Data in patients with AD and EC subjects showed that near-maximal inhibition of brain MAO-B was achieved with 1 mg sembragiline daily, regardless of the population, whereas lower doses resulted in lower and variable brain MAO-B inhibition. CONCLUSIONS: This PET study confirmed that daily treatment of at least 1 mg sembragiline resulted in near-maximal inhibition of brain MAO-B enzyme in patients with AD.

Pharmacokinetics of obinutuzumab in Chinese patients with B-cell lymphomas.

AIM: The Phase Ib GERSHWIN study (NCT01680991) assessed the pharmacokinetic (PK) profile of obinutuzumab following multiple intravenous (i.v.) doses to Chinese patients with B-cell lymphomas, and compared findings with previous obinutuzumab PK studies in mainly Caucasian (non-Chinese) patients. METHODS: GERSHWIN was an open-label, single-arm intervention study. Patients aged >18 years with CD20+ relapsed/refractory chronic lymphocytic leukaemia (CLL), diffuse large B-cell lymphoma (DLBCL) or follicular lymphoma (FL) were enrolled from four centres in China. The treatment period was 24 weeks; patients received obinutuzumab 1000 mg i.v. on Days (D)1, 8 and 15 of Cycle (C)1 (CLL patients: first infusion split over 2 days) and on D1 of C2-8 (all cycles: 21 days). PK parameters were estimated using non-compartmental analysis (NCA), and a population PK analysis was used to determine whether observed GERSHWIN PK data were in accordance with previous obinutuzumab PK studies in non-Chinese patients. RESULTS: The PK analysis population included 48 patients: 28 patients completed all treatment cycles. NCA showed a similar PK profile in Chinese patients with FL, DLBCL and CLL. Steady-state concentrations of obinutuzumab appeared to be reached at the start of C2 irrespective of histology. There was no apparent relationship between body weight and systemic exposure. Most PK profiles observed in GERSHWIN lay within the 90% prediction interval of simulated profiles. CONCLUSIONS: Obinutuzumab exposure was comparable in CLL, DLBCL and FL patients. NCA and population PK analysis indicate that PK characteristics of Chinese patients with B-cell lymphomas are similar to those in non-Chinese patients.

First-in-Man Study With Inclacumab, a Human Monoclonal Antibody Against P-selectin.

Inclacumab, a novel monoclonal antibody against P-selectin in development for the treatment and prevention of atherosclerotic cardiovascular diseases, was administered in an ascending single-dose study as intravenous infusion to evaluate safety, pharmacokinetics, and pharmacodynamics. Fifty-six healthy subjects were enrolled in this randomized, double-blind placebo-controlled study. Each dose level (0.03-20 mg/kg) was investigated in separate groups of 8 subjects (6 on inclacumab, 2 on placebo). Platelet-leukocyte aggregates, free/total soluble P-selectin concentration ratio, drug concentrations, bleeding time, platelet aggregation, antibody formation, and routine laboratory parameters were measured frequently until 32 weeks. Pharmacokinetic profiles were indicative of target-mediated drug disposition. Platelet-leukocyte aggregate inhibition and soluble P-selectin occupancy showed dose dependency and were strongly correlated to inclacumab plasma concentrations, with IC50 of 740 and 4600 ng/mL, respectively. Inclacumab was well tolerated by the majority of subjects and did neither affect bleeding time nor platelet aggregation. These findings allowed the investigation of the potential beneficial therapeutic use of inclacumab in patient study.

The effect of aleglitazar on the pharmacokinetics and pharmacodynamics of S- and R-warfarin in healthy male subjects.

: Aleglitazar acts through balanced activation of peroxisome proliferator-activated receptors α and γ; warfarin is a commonly prescribed anticoagulant. Given the extent of cardiovascular disease in patients with type 2 diabetes, cotreatment with aleglitazar and warfarin is likely in this population. This open-label, randomized, 2-period, crossover study in 12 healthy male subjects investigated the potential for drug-drug interactions between warfarin and aleglitazar (final data drawn from 11 white subjects). The primary objective was to investigate the effect of aleglitazar on the pharmacokinetic properties of S-warfarin and on the pharmacodynamics of the racemic mixture; the secondary objectives included the effect of aleglitazar on R-warfarin pharmacokinetics and of racemic warfarin on aleglitazar pharmacokinetics. Subjects were randomized to single-dose warfarin on day 1 or aleglitazar once daily (12 days) plus single-dose warfarin on day 6 followed by a 14-day washout period, then crossover. Coadministration of aleglitazar reduced S- and R-warfarin exposure (AUC0-∞) by 18% and 13%, respectively, but did not change its pharmacodynamic effects (prothrombin time and factor VII activity). After warfarin dosing, aleglitazar trough concentrations remained within the same range. These findings indicate that coadministration of aleglitazar and warfarin is unlikely to affect the efficacy or safety of either agent.

CEA-CD3 bispecific antibody cibisatamab with or without atezolizumab in patients with CEA-positive solid tumours: results of two multi-institutional Phase 1 trials.

Cibisatamab is a bispecific antibody-based construct targeting carcinoembryonic antigen (CEA) on tumour cells and CD3 epsilon chain as a T-cell engager. Here we evaluated cibisatamab for advanced CEA-positive solid tumours in two open-label Phase 1 dose-escalation and -expansion studies: as a single agent with or without obinutuzumab in S1 (NCT02324257) and with atezolizumab in S2 (NCT02650713). Primary endpoints were safety, dose finding, and pharmacokinetics in S1; safety and dose finding in S2. Secondary endpoints were anti-tumour activity (including overall response rate, ORR) and pharmacodynamics in S1; anti-tumour activity, pharmacodynamics and pharmacokinetics in S2. S1 and S2 enrolled a total of 149 and 228 patients, respectively. Grade ≥3 cibisatamab-related adverse events occurred in 36% of S1 and 49% of S2 patients. The ORR was 4% in S1 and 7% in S2. In S2, patients with microsatellite stable colorectal carcinoma (MSS-CRC) given flat doses of cibisatamab and atezolizumab demonstrated an ORR of 14%. In S1 and S2, 40% and 52% of patients, respectively, developed persistent anti-drug antibodies (ADAs). ADA appearance could be mitigated by obinutuzumab-pretreatment, with 8% of patients having persistent ADAs. Overall, cibisatamab warrants further exploration in immunotherapy combination strategies for MSS-CRC.

Rituximab pediatric drug development: Pharmacokinetic and pharmacodynamic modeling to inform regulatory approval for rituximab treatment in patients with granulomatosis with polyangiitis or microscopic polyangiitis.

Anti-neutrophil cytoplasmic antibody-associated vasculitides granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA) are rare, potentially organ- and life-threatening autoimmune conditions affecting adult and pediatric patients. An open-label phase II study was conducted to determine safe and effective dosing regimens of rituximab in pediatric patients with GPA/MPA. To determine the selection of an appropriate dose regimen in children for induction and maintenance, a population pharmacokinetic approach was used (nonlinear mixed-effect modeling), combining pediatric data with data from adults with GPA/MPA. The time course of B-cell depletion was assessed in both populations. The exposure-effect relationship was assessed by logistic regression. Twenty-five pediatric patients (80% female patients; age range, 6-17 years) were enrolled in the trial and received the induction regimen of intravenous rituximab 375 mg/m2 weekly for 4 weeks, which resulted in a similar exposure to that of adults. Based on pharmacokinetic modeling, a maintenance dosing regimen of 250 mg/m2 administered twice over 14 days followed by 250 mg/m2 every 6 months is expected to result in similar rituximab exposure as that of adults receiving the approved maintenance dose of 500 mg administered twice over 14 days followed by 500 mg every 6 months. The time course of B-cell depletion was similar between the pediatric and adult populations, supporting the similarities in response in both populations and allowing extrapolation to patients less than 6 years old. Using a partial extrapolation approach helped identify safe and effective dosing regimens of rituximab in pediatric patients with GPA/MPA and lead to regulatory approval.

Preclinical InVivo Data Integrated in a Modeling Network Informs a Refined Clinical Strategy for a CD3 T-Cell Bispecific in Combination with Anti-PD-L1.

TYRP1-TCB is a CD3 T-cell bispecific (CD3-TCB) antibody for the treatment of advanced melanoma. A tumor growth inhibition (TGI) model was developed using mouse xenograft data with TYRP1-TCB monotherapy or TYRP1-TCB plus anti-PD-L1 combination. The model was translated to humans to inform a refined clinical strategy. From xenograft mouse data, we estimated an EC50 of 0.345 mg/L for TYRP1-TCB, close to what was observed in vitro using the same tumor cell line. The model showed that, though increasing the dose of TYRP1-TCB in monotherapy delays the time to tumor regrowth and promotes higher tumor cell killing, it also induces a faster rate of tumor regrowth. Combination with anti-PD-L1 extended the time to tumor regrowth by 25% while also decreasing the tumor regrowth rate by 69% compared to the same dose of TYRP1-TCB alone. The model translation to humans predicts that if patients' tumors were scanned every 6 weeks, only 46% of the monotherapy responders would be detected even at a TYRP1-TCB dose resulting in exposures above the EC90. However, combination of TYRP1-TCB and anti-PD-L1 in the clinic is predicted to more than double the overall response rate (ORR), duration of response (DoR) and progression-free survival (PFS) compared to TYRP1-TCB monotherapy. As a result, it is highly recommended to consider development of CD3-TCBs as part of a combination therapy from the outset, without the need to escalate the CD3-TCB up to the Maximum Tolerated Dose (MTD) in monotherapy and without gating the combination only on RECIST-derived efficacy metrics.

Phase IIa Global Study Evaluating Rituximab for the Treatment of Pediatric Patients With Granulomatosis With Polyangiitis or Microscopic Polyangiitis.

OBJECTIVE: To assess the safety, tolerability, pharmacokinetics, and efficacy of rituximab (RTX) in pediatric patients with granulomatosis with polyangiitis (GPA) or microscopic polyangiitis (MPA). METHODS: The Pediatric Polyangiitis Rituximab Study was a phase IIa, international, open-label, single-arm study. During the initial 6-month remission-induction phase, patients received intravenous infusions of RTX (375 mg/m2 body surface area) and glucocorticoids once per week for 4 weeks. During the follow-up period, patients could receive further treatment, including RTX, for GPA or MPA. The safety, pharmacokinetics, pharmacodynamics, and exploratory efficacy outcomes with RTX were evaluated. RESULTS: Twenty-five pediatric patients with new-onset or relapsing disease were enrolled at 11 centers (19 with GPA [76%] and 6 with MPA [24%]). The median age was 14 years (range 6-17 years). All patients completed the remission-induction phase. During the overall study period (≤4.5 years), patients received between 4 and 28 infusions of RTX. All patients experienced ≥1 adverse event (AE), mostly grade 1 or grade 2 primarily infusion-related reactions. Seven patients experienced 10 serious AEs, and 17 patients experienced 31 infection-related AEs. No deaths were reported. RTX clearance correlated with body surface area. The body surface area-adjusted RTX dosing regimen resulted in similar exposure in both pediatric and adult patients with GPA or MPA. Remission, according to the Pediatric Vasculitis Activity Score, was achieved in 56%, 92%, and 100% of patients by months 6, 12, and 18, respectively. CONCLUSION: In pediatric patients with GPA or MPA, RTX is well tolerated and effective, with an overall safety profile comparable to that observed in adult patients with GPA or MPA who receive treatment with RTX. RTX is associated with a positive risk/benefit profile in pediatric patients with active GPA or MPA.

The MDM2 antagonist idasanutlin in patients with polycythemia vera: results from a single-arm phase 2 study.

Idasanutlin, an MDM2 antagonist, showed clinical activity and a rapid reduction in JAK2 V617F allele burden in patients with polycythemia vera (PV) in a phase 1 study. This open-label phase 2 study evaluated idasanutlin in patients with hydroxyurea (HU)-resistant/-intolerant PV, per the European LeukemiaNet criteria, and phlebotomy dependence; prior ruxolitinib exposure was permitted. Idasanutlin was administered once daily on days 1 through 5 of each 28-day cycle. The primary end point was composite response (hematocrit control and spleen volume reduction > 35%) in patients with splenomegaly and hematocrit control in patients without splenomegaly at week 32. Key secondary end points included safety, complete hematologic response (CHR), patient-reported outcomes, and molecular responses. All patients (n = 27) received idasanutlin; 16 had response assessment (week 32). Among responders with baseline splenomegaly (n = 13), 9 (69%) attained any spleen volume reduction, and 1 achieved composite response. Nine patients (56%) achieved hematocrit control, and 8 patients (50%) achieved CHR. Overall, 43% of evaluable patients (6/14) showed a ≥50% reduction in the Myeloproliferative Neoplasm Symptom Assessment Form Total Symptom Score (week 32). Nausea (93%), diarrhea (78%), and vomiting (41%) were the most common adverse events, with grade ≥ 3 nausea or vomiting experienced by 3 patients (11%) and 1 patient (4%), respectively. Reduced JAK2 V617F allele burden occurred early (after 3 cycles), with a median reduction of 76%, and was associated with achieving CHR and hematocrit control. Overall, the idasanutlin dosing regimen showed clinical activity and rapidly reduced JAK2 allele burden in patients with HU-resistant/- intolerant PV but was associated with low-grade gastrointestinal toxicity, leading to poor long-term tolerability. This trial was registered at www.clinincaltrials.gov as #NCT03287245.

Idasanutlin plus cytarabine in relapsed or refractory acute myeloid leukemia: results of the MIRROS trial.

The phase 3 MIRROS (MDM2 antagonist Idasanutlin in Relapsed or Refractory acute myeloid leukemia [AML] for Overall Survival) trial (NCT02545283) evaluated the efficacy and safety of the small-molecule MDM2 antagonist idasanutlin plus cytarabine in patients with relapsed/refractory (R/R) AML. Adults (n = 447) with R/R AML whose disease relapsed or was refractory after ≤2 prior induction regimens as initial treatment or following salvage chemotherapy regimen, with Eastern Cooperative Oncology Group performance status ≤2 were enrolled regardless of TP53 mutation status and randomly assigned 2:1 to idasanutlin 300 mg or placebo orally twice daily plus cytarabine 1 g/m2 IV on days 1 to 5 of 28-day cycles. At primary analysis (cutoff, November 2019), 436 patients were enrolled, including 355 in the TP53 wild-type intention-to-treat (TP53WT-ITT) population. The primary endpoint, overall survival in the TP53WT-ITT population, was not met (median, 8.3 vs 9.1 months with idasanutlin-cytarabine vs placebo-cytarabine; stratified hazard ratio [HR], 1.08; 95% confidence interval [CI], 0.81-1.45; P = .58). The complete remission (CR) rate, a key secondary endpoint, was 20.3% vs 17.1% (odds ratio [OR], 1.23; 95% CI, 0.70-2.18). The overall response rate (ORR) was 38.8% vs 22.0% (OR, 2.25; 95% CI, 1.36-3.72). Common any-grade adverse events (≥10% incidence in any arm) were diarrhea (87.0% vs 32.9%), febrile neutropenia (52.8% vs 49.3%), and nausea (52.5% vs 31.5%). In summary, despite improved ORR, adding idasanutlin to cytarabine did not improve overall survival or CR rates in patients with R/R AML.

Anti-CD20 treatment for B-cell malignancies: current status and future directions.

INTRODUCTION: The introduction of anti-CD20 monoclonal antibody therapy with rituximab in the 1990s greatly improved outcomes for patients with B-cell malignancies. Disease resistance or relapse after successful initial therapy and declining efficacy of subsequent rounds of treatment were the basis for the development of alternative anti-CD20-based antibody therapies. AREAS COVERED: The novel anti-CD20 antibodies of atumumab, ublituximab, and obinutuzumab were developed to be differentiated via structural and mechanistic features over rituximab. We provide an overview of preclinical and clinical data, and demonstrate ways in which the pharmacodynamic properties of these novel agents translate into clinical benefit for patients. EXPERT OPINION: Of the novel anti-CD20 antibodies, only obinutuzumab has shown consistently improved efficacy over rituximab in randomized pivotal trials in indolent non-Hodgkin lymphoma and chronic lymphocytic leukemia. The Phase 3 GALLIUM trial demonstrated significant improvements in progression-free survival with obinutuzumab-based immunochemotherapy over rituximab-based immunochemotherapy. Novel combinations of obinutuzumab, including with chemotherapy-free options are being explored, such as with the newly approved combinations of obinutuzumab with venetoclax, ibrutinib, or acalabrutinib. The biggest unmet need remains in the treatment of diffuse large B-cell lymphoma; emerging options in this field include the use of CAR-T cells and T-cell bispecific antibodies.

Population pharmacokinetic and exposure-response analyses of intravenous and subcutaneous rituximab in patients with chronic lymphocytic leukemia.

A subcutaneous formulation of the anti-CD20 antibody rituximab has been developed. Fixed-dose subcutaneous rituximab delivers noninferior serum trough concentrations (Ctrough ), ensuring similar target saturation and comparable efficacy/safety, to intravenous rituximab, but with simplified and shortened preparation and administration. We aimed to characterize the pharmacokinetic (PK) and exposure-response properties of subcutaneous rituximab. Data from two clinical trials were analyzed to describe PKs and pharmacodynamics in patients with chronic lymphocytic leukemia following intravenous and subcutaneous rituximab administration. Intravenous and subcutaneous rituximab were described by a linear two-compartment population PK model with time-dependent and time-independent clearances, and first-order subcutaneous absorption. Main covariates influencing exposure were body size and baseline white blood cell count. Occurrence of adverse events was not correlated with rituximab exposure. Although greater and more sustainable B-cell depletion was observed with higher exposure, inherent limitations to the data (use of one dose level, and time-dependent and target-impacted PKs) prevented reliable assessment of exposure-response relationships.

Quantitative Clinical Pharmacology Supports the Bridging From i.v. Dosing and Approval of s.c. Rituximab in B-Cell Hematological Malignancies.

A fixed-dose subcutaneous (s.c.) formulation of the anti-CD20 antibody, rituximab, has been developed to address safety, infusion time, and patient comfort concerns relating to intravenous (i.v.) dosing, and has been approved based upon a pharmacokinetic (PK)-clinical bridging strategy, which demonstrated noninferiority of s.c. vs. i.v. dosing in malignancies, including follicular lymphoma (FL) and chronic lymphocytic leukemia (CLL). A clinical development plan was undertaken to identify rituximab s.c. doses achieving noninferior exposure to rituximab i.v., and to confirm PK-clinical bridging, with the same efficacy and similar safety. This drew upon data from 1,579 patients with FL, CLL, or diffuse large B-cell lymphoma in 5 clinical studies, and showed minimum steady-state serum concentration (Ctrough ) as the most appropriate exposure bridging measure. Population PK models were developed, simulations were run using covariates and PK parameters from clinical studies, and exposure-efficacy and -safety analyses performed. Population PKs showed a two-compartment model with time-dependent and -independent clearances. Clearance and volume were predominantly influenced by body surface area; disposition and elimination were similar for the s.c. and i.v. formulations. After s.c. administration, patients with FL and CLL achieved noninferior exposures to i.v. dosing. Overall, rituximab exposure and route of administration did not influence clinical responses in patients with FL or CLL, and there was no association between exposure and safety events. Ctrough was shown to be an effective pharmacologic-clinical bridging parameter for rituximab in patients with FL or CLL. Clinically effective exposures are achieved with either s.c. or i.v. dosing.

Effect of saquinavir/ritonavir (1000/100 mg bid) on the pharmacokinetics of methadone in opiate-dependent HIV-negative patients on stable methadone maintenance therapy.

This study was performed to determine the effect of two protease inhibitors, saquinavir (SQV, oral 1000 mg bid) boosted by ritonavir (RTV, oral 100 mg bid), on pharmacokinetics (PK) of methadone in opiate-dependent HIV-negative patients on stable methadone maintenance therapy. This was a two-center, open-label, one-sequence cross-over, multiple-dose study in 13 HIV-negative patients who were on stable methadone therapy (oral, 60-120 mg qd). All patients continued methadone treatment on days 2-15. All patients received SQV/RTV in combination with methadone from days 2-15. PK of methadone was assessed on day 1 (alone) and on day 15 when methadone treatment was combined with SQV/RTV at steady state. Twelve patients completed the study. Median age, body weight and height were 50 years (range: 24-54 years), 80 kg (range: 57-97 kg) and 174 cm (range: 163-189 cm), respectively. All patients were Caucasian, and 11 were smokers. Median methadone dose was 85 mg qd. Geometric mean area under curve of the plasma concentration-time curve over 24 hour dosing interval (AUC(0-24 hour)) ratio of methadone with and without SQV/RTV was 0.81% (90% confidence interval: 71-91%). There was no significant plasma protein-binding displacement of methadone by SQV/RTV. The combination of SQV/RTV and methadone was well tolerated. There were no clinically significant adverse events or significant changes in laboratory parameters, electrocardiograms or vital signs. The 19% decrease in R-methadone AUC(0-24 hour) in the presence of SQV/RTV was not clinically relevant. There appears to be no need for methadone dose adjustment when methadone (60-120 mg qd) and SQV/RTV (1000/100 mg bid) are coadministered.