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This study evaluated venetoclax population pharmacokinetics (popPK) in patients with treatment-naïve acute myeloid leukemia and assessed the relationship between venetoclax exposure and clinical response for venetoclax in combination with either a hypomethylating agent (HMA) or low-dose cytarabine (LDAC). A total of 771 patients who received venetoclax from 5 Phase 1-3 studies were included in the popPK model. Exposure-response analyses included data from 575 patients for venetoclax/placebo plus HMA and 279 patients for venetoclax/placebo plus LDAC. The popPK model successfully characterized venetoclax plasma concentrations over time and confirmed venetoclax exposure did not vary significantly with age, weight, sex, mild to moderate hepatic impairment, or mild to severe renal impairment. Asian patients had 67% higher mean relative bioavailability than non-Asian patients, however the range of exposures in Asian patients was similar to non-Asian patients. For all efficacy endpoints with both treatment combinations, efficacy was higher in the venetoclax treatment groups compared with the respective control arm of placebo plus azacitidine or LDAC. Within patients who received venetoclax, no significant exposure-efficacy relationships were identified for either treatment combination, indicating that the beneficial effects of venetoclax were already maximized in the dose ranges studied. There was no apparent effect of venetoclax exposure on treatment-emergent Grade ≥3 thrombocytopenia or infections for either combination. Rates of treatment-emergent Grade ≥3 neutropenia were higher in the venetoclax treatment arms compared with the respective control arms; however, within patients who received venetoclax, there was only a shallow relationship or no apparent relationship with venetoclax exposure for venetoclax plus HMA or LDAC, respectively. Along with the efficacy and safety data previously published, the exposure-response analyses support the venetoclax dose regimens of 400 mg once daily (QD) plus HMA and 600 mg QD plus LDAC in treatment-naïve AML patients who are ineligible for intensive chemotherapy.

PURPOSE The CLL14 study has established one-year fixed-duration treatment of venetoclax and obinutuzumab (Ven-Obi) for patients with previously untreated chronic lymphocytic leukemia. With all patients off treatment for at least three years, we report a detailed analysis of minimal residual disease (MRD) kinetics and long-term outcome of patients treated in the CLL14 study. PATIENTS AND METHODS Patients were randomly assigned to receive six cycles of obinutuzumab with 12 cycles of venetoclax or 12 cycles of chlorambucil (Clb-Obi). Progression-free survival (PFS) was the primary end point. Key secondary end points included rates of undetectable MRD and overall survival. To analyze MRD kinetics, a population-based growth model with nonlinear mixed effects approach was developed. RESULTS Of 432 patients, 216 were assigned to Ven-Obi and 216 to Clb-Obi. Three months after treatment completion, 40% of patients in the Ven-Obi arm (7% in the Clb-Obi arm) had undetectable MRD levels < 10−6 by next-generation sequencing in peripheral blood. Median MRD doubling time was longer after Ven-Obi than Clb-Obi therapy (median 80 v 69 days). At a median follow-up of 52.4 months, a sustained significant PFS improvement was observed in the Ven-Obi arm compared with Clb-Obi (median not reached v 36.4 months; hazard ratio 0.33; 95% CI, 0.25 to 0.45; P < .0001). The estimated 4-year PFS rate was 74.0% in the Ven-Obi and 35.4% in the Clb-Obi arm. No difference in overall survival was observed (hazard ratio 0.85; 95% CI, 0.54 to 1.35; P = .49). No new safety signals occurred. CONCLUSION Appearance of MRD after Ven-Obi is significantly slower than that after Clb-Obi with more effective MRD reduction. These findings translate into a superior long-term efficacy with the majority of Ven-Obi–treated patients remaining in remission.

Purpose The CD79b-targeted antibody–drug conjugate polatuzumab vedotin (pola), alone and with chemoimmunotherapy, has clinical efficacy and a tolerable safety profile in B-cell non-Hodgkin lymphoma (B-NHL). We assessed (a) whether exposure from global studies of pola is comparable to Asian patients, and (b) if the recommended pola dose is appropriate in Asian patients based on exposure. Methods The pharmacokinetics (PK) of pola in Asian and global populations was characterized for three analytes (antibody-conjugated monomethyl auristatin E (MMAE) [acMMAE], total antibody, and unconjugated MMAE) in five phase 1b/2 single-agent and combination studies in B-NHL patients (JO29138 [JAPICCTI‐142580], DCS4968g [NCT01290549], GO27834 [NCT01691898], GO29044 [NCT01992653], and GO29365 [NCT02257567]). PK data were compared between Japanese phase 1 JO29138 (JAPICCTI‐142580) and global phase 1 DCS4968g (NCT01290549) studies and between Asian and non-Asian patients in the randomized relapsed/refractory B-NHL cohorts of the phase 1b/2 study GO29365 (NCT02257567). A population PK (popPK) model was used to assess the effects of Asian race and region on acMMAE and unconjugated MMAE exposure. Results PK non-compartmental analysis (NCA) parameters for the key analyte acMMAE in the Japanese JO29138 (JAPICCTI‐142580) and global phase 1 DCS4968g (NCT01290549) studies were similar. In GO29365 (NCT02257567), the phase 1b/2 combination study, mean exposure to the analytes was generally lower in Asian patients (by ~ 9.9 to 17.5%), but not to a clinically meaningful extent. Overall, the popPK model further suggested comparable PK in Asian patients with B-NHL (race or region) versus non-Asian patients. Conclusion Race has no clinically meaningful effect on pola PK. These results (and observations from efficacy/safety exposure–response analyses) support no pola dose adjustments are warranted for Asian patients with DLBCL.

Introduction Outcomes remain poor in patients with diffuse large B cell lymphoma (DLBCL) who overexpress BCL-2 protein. We present population pharmacokinetics (PopPK) and exposure–response (ER) analyses for venetoclax (a selective BCL-2 inhibitor) administered with rituximab-cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) in patients with relapsed/refractory (R/R) and previously untreated (1L) non-Hodgkin lymphoma (NHL) from the phase 1b/2 CAVALLI study, to confirm dose selection for future studies. Methods Analyses included 216 patients with R/R or 1L NHL treated for eight 21-day cycles with 400–800 mg venetoclax (cycle 1: days 4–10; cycles 2–8: days 1–10) in combination with R for eight cycles and CHOP for 6–8 cycles. A legacy PopPK model for venetoclax was used to describe the observed data and provide post hoc PK parameters. Venetoclax steady-state exposure (AUCss) was used to predict clinical efficacy, safety, or tolerability. To isolate the effect of venetoclax, ER analyses referenced data from the R-CHOP arm of a historical control study, GOYA, in 1L DLBCL. Results There was no significant association between venetoclax AUCss and progression-free survival or complete response either for all-comers or the BCL-2-immunohistochemistry-positive subpopulation. No statistically significant trends were observed with venetoclax AUCss and the key grade ≥ 3 adverse events and serious adverse events. Similar dose intensities were observed for venetoclax and R-CHOP components across venetoclax exposures, suggesting venetoclax did not impact delivery of the R-CHOP backbone. Conclusions The PopPK and ER analyses, in addition to the positive benefit–risk observed in the clinical data, support the selection of 800 mg venetoclax given with R-CHOP for future studies in BCL-2-immunohistochemistry-positive patients with 1L DLBCL. Trial Registration ClinicalTrials.gov Identifier NCT02055820. Supplementary Information The online version contains supplementary material available at 10.1007/s12325-021-01919-z.

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–versus 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.

Model-informed drug development (MIDD) has become an important approach to improving clinical trial efficiency, optimizing drug dosing, and proposing drug labeling in the absence of dedicated clinical trials. For the first time, we developed a physiologically based pharmacokinetic (PBPK) model-based approach to assess CYP3A-mediated drug-drug interaction (DDI) risk for polatuzumab vedotin (Polivy), an anti-CD79b-vc-monomethyl auristatin E (MMAE) antibody-drug conjugate (ADC). The model was developed and verified using data from the existing clinical DDI study for brentuximab vedotin, a similar vc-MMAE ADC. Analogous to the brentuximab vedotin clinical study, polatuzumab vedotin at the proposed labeled dose was predicted to have a limited drug interaction potential with strong CYP3A inhibitor and inducer. Polatuzumab vedotin was also predicted to neither inhibit nor induce CYP3A. The present work demonstrated a high-impact application using a PBPK MIDD approach to predict the CYP3A-mediated DDI to enable drug labeling in the absence of any dedicated clinical DDI study. The key considerations for the PBPK report included in the Biologics License Application/Marketing Authorization Application submission, as well as the strategy and responses to address some of the critical and challenging questions from the health authorities following the submission are also discussed. Our experience and associated perspective using a PBPK approach to ultimately enable a drug interaction label claim for polatuzumab vedotin in lieu of a dedicated clinical DDI study, as well as the interactions with the regulatory agencies, further provides confidence in applying MIDD to accelerate the registration and approval of new drug therapies.

Exposure-response relationships were investigated to assess the risk/benefit of polatuzumab vedotin (pola) + bendamustine-rituximab (pola + BR) in relapsed/refractory diffuse large B-cell lymphoma (R/R DLBCL). Analyses were conducted in pivotal study GO29365 (NCT02257567; BR/pola + BR/pola + BG [BG: bendamustine-obinutuzumab]; 1.8 mg/kg pola, every 3 weeks [Q3W], six cycles), and supportive studies DCS4968g (NCT01290549) and GO27834 (NCT01691898) (pola/pola + R/pola + G; 0.1-2.4 mg/kg pola Q3W; eight-cycle landmark), separately. Exposure was characterized as simulated cycle-6 AUC and

Minimal residual disease (MRD) is an important emerging clinical end point in chronic lymphocytic leukemia (CLL). The objective of this research was to develop an integrated mechanistic model to evaluate the impact of venetoclax-rituximab combination therapy on MRD kinetics. Using data from 435 patients with relapsed or refractory CLL, an integrated model was developed and validated that accounted for venetoclax dosing and pharmacokinetics, rituximab treatment, absolute lymphocyte count, and blood and bone marrow (BM) MRD data. Simulations of venetoclax-rituximab (six cycles) combination predicted the proportion (90% confidence interval) of patients with BM MRD below 10-4 to be 57% (54-61%) and 63% (59-67%) at 12 and 24 months of treatment, respectively. Continued venetoclax treatment to 48 months only increased the predicted rate of negative BM MRD to 66% (63-70%). These results indicate that treatment with venetoclax-rituximab combination for a finite 2-year period would nearly maximize the rate of negative BM MRD (< 10-4 ). Preliminary clinical data agree with these predictions and more long-term follow-up data are awaited to confirm the same.

To evaluate the safety, tolerability, and pharmacokinetics of XL647 and determine the maximum tolerated dose (MTD) of oral XL647 once-daily using intermittent or continuous dosing schedules. Patients with advanced solid malignancies were enrolled in successive cohorts to receive escalating dose levels of oral once-daily XL647 using two different dosing schedules: 5 consecutive days of every 14-day cycle (study XL647-001) or continuously over 28-day cycles (study XL647-002). PK sampling was performed to determine Cmax, and AUC. Patients remained on study until progressive disease or unacceptable AEs. In XL647-001, 42 individuals were enrolled across 9 dose levels. The most frequently occurring drug-related AEs were diarrhea, nausea, rash, and fatigue. Expansion of the 4.68 mg/kg cohort to 6 patients occurred without further dose-limiting toxicities (DLTs) and this was considered the MTD. In XL647-002, 31 patients were enrolled across 5 dose levels. A DLT of grade 3 pneumonitis occurred in 1/6 patients at 300 mg, which was declared the MTD. The most common AEs included grade 1/2 rash, diarrhea, fatigue, dysgeusia, and QTc prolongation. Levels of pharmacodynamic plasma markers were not consistently changed after XL647 and no conclusions could be drawn with this limited data set. For oral XL647, the MTD was 4.68 mg/kg or 350 mg fixed dose when administered once-daily for 5 consecutive days of every 14-day cycle and was 300 mg when administered once-daily continuously. XL647 was well tolerated at doses up to the MTD.

Background In the phase III METEOR trial, tyrosine kinase inhibitor cabozantinib significantly improved progression-free survival (PFS), objective response rate (ORR), and overall survival compared to everolimus in patients with advanced renal cell carcinoma (RCC) who had received prior VEGFR inhibitor therapy. In METEOR, RCC patients started at a daily 60-mg cabozantinib tablet (Cabometyx™) dose but could reduce to 40- or 20-mg to achieve a tolerated exposure. Objectives and methods Exposure–response (ER) models were developed to characterize the relationship between cabozantinib at clinically relevant exposures in RCC patients enrolled in METEOR and efficacy (PFS and tumor response) and safety endpoints. Results Compared to the average steady-state cabozantinib concentration for a 60-mg dose, exposures at simulated 40- and 20-mg starting doses were predicted to result in higher risk of disease progression or death [hazard ratios (HRs) of 1.10 and 1.39, respectively], lower maximal median reduction in tumor size (− 11.9 vs − 9.1 and − 4.5%, respectively), and lower ORR (19.1 vs 15.6 and 8.7%, respectively). The 60-mg exposure was also associated with higher risk for selected adverse events (AEs) palmar-plantar erythrodysesthesia syndrome (grade ≥ 1), fatigue/asthenia (grade ≥ 3), diarrhea (grade ≥ 3), and hypertension (predicted HRs of 2.21, 2.01, 1.78, and 1.85, respectively) relative to the predicted average steady-state cabozantinib concentration for a 20-mg starting dose. Conclusion ER modeling predicted that cabozantinib exposures in RCC patients at the 60-mg starting dose would provide greater anti-tumor activity relative to exposures at simulated 40- and 20-mg starting doses that were associated with decreased rates of clinically relevant AEs. Electronic supplementary material The online version of this article (10.1007/s00280-018-3579-7) contains supplementary material, which is available to authorized users.

Purpose An integrated population pharmacokinetic (popPK) model was developed to describe the pharmacokinetics (PK) of tyrosine kinase inhibitor cabozantinib in healthy volunteers (HVs) and patients with various cancer types and to identify any differences in cabozantinib PK across these populations. Methods Plasma concentration data used to develop the popPK model were obtained from nine clinical trials (8072 concentrations from 1534 HVs or patients) of cabozantinib in HVs and patients with renal cell carcinoma (RCC), medullary thyroid carcinoma (MTC), glioblastoma multiforme, castration-resistant prostate cancer, or other advanced malignancies. Results PK data across studies were adequately characterized by a two-compartment disposition model with dual first- and zero-order absorption processes and first-order elimination. Baseline demographic covariates (age, weight, gender, race, and cancer type) were generally predicted to have a small-to-moderate impact on apparent clearance (CL/F). However, MTC cancer type did show an approximately 93% higher CL/F relative to HVs following chronic dosing, resulting in approximately 40–50% lower predicted steady-state cabozantinib plasma concentrations. Conclusion This popPK analysis showed cabozantinib CL/F values to be higher for patients with MTC and may account for the higher dosage required in this patient population (140-mg) to achieve plasma exposures comparable to those in patients with RCC and other tumor types administered a 60-mg cabozantinib tablet dose. Possible factors that may underlie the higher cabozantinib clearance observed in MTC patients are discussed. Electronic supplementary material The online version of this article (10.1007/s00280-018-3581-0) contains supplementary material, which is available to authorized users.

This study evaluated factors impacting QTc interval in a phase 3 trial of cabozantinib in progressive, metastatic, medullary thyroid cancer (MTC). Electrocardiogram (12-lead ECG) measurements were obtained at screening, and at pre-dose, and 2, 4, and 6 h post-dose on Days 1 and 29 in a phase 3 study in patients with MTC treated with cabozantinib (140 mg/day). Central tendency analyses were conducted on baseline-corrected QTc values. Linear and nonlinear mixed-effects models were used to evaluate potential factors affecting the QTc interval, including serum electrolytes, patient demographics, and cabozantinib concentration. Central tendency analysis showed that oral cabozantinib (140 mg/day) produced a 10–15 ms increase in delta–delta Fridericia corrected QT (∆∆QTcF) and delta–delta study-specific corrected QT (∆∆QTcS) on Day 29, but not on Day 1. Further analysis showed that QTcS provided a slightly more accurate QT correction than QTcF. Mixed-effects models evaluating serum electrolytes, age, sex, and cabozantinib concentration showed that decreased serum calcium and potassium could explain the majority of cabozantinib treatment-associated QTcS prolongation observed in this study. Cabozantinib treatment prolongs the ∆∆QTcF interval by 10–15 ms. There was the absence of a strong relationship between cabozantinib concentration and QTcS prolongation. Cabozantinib treatment effects on serum calcium and potassium best explain the QTcS prolongation observed in this study.

Context: Myelodysplastic syndromes (MDS) represent a group of bone marrow disorders involving cytopenia, hypercellular bone marrow, and dysplastic hematopoietic progenitors. Death is commonly caused by the effects of cytopenia, leading to infections or bleeding [1]. Finding efficacious treatment regimens in MDS remains a challenge as it involves understanding of both disease induced and treatment related cytopenias. Objective: The objective was to develop a semi-mechanistic model of disease progression in MDS based on clinical data, involving relevant hematopoietic cells that can describe the effect of drug intervention with venetoclax azacitidine combination therapy. The model was subsequently used to simulate different treatment regimens (with respect to dose, dosing duration in a cycle, and number of cycles) and compare the outcomes. Study Design and Data: Data from an ongoing Phase 1b study evaluating the safety and efficacy of venetoclax (400 mg or 800 mg for 28 days or 100 mg to 400 mg for 14 days in each 28-day cycle) with azacitidine (75 mg/m2 on days 1-7 of each cycle) in treatment-naive patients with higher-risk MDS were used for the analysis. The data contained venetoclax concentrations, neutrophil, red blood cell, and platelet count in the blood and blasts in the bone marrow. Methods: An integrated semi-mechanistic pharmacokinetic-pharmacodynamic (PK-PD) model was developed that accounted for venetoclax PK and azacitidine treatment to describe time dynamics of neutrophils, red blood cells, and platelets. The model also included crowding in the bone marrow due to excess stem cells, MDS blasts, and progenitor cells, and its effect on hematopoiesis. Results: The model described the observed clinical data well and showed predictive ability across considered cell types. Complete remission (CR) and marrow complete remission (mCR) rates were predicted close to observed rates in the study. Simulated efficacy (recovery of blast count, CR, and mCR rates) and safety (neutropenia and thrombocytopenia) endpoints are comparable to the expected outcomes from various dosing regimens. Conclusions: A model describing drug-disease interactions in MDS was developed that integrates multiple end points and differentiates disease driven from drug-induced cytopenia. Reference: [1] Dayyani, F, et al. Cause of death in patients with lower-risk myelodysplastic syndrome. Cancer. 2010 May 1; 116.9:2174-2179. Disclosures: The analysis presented was funded by AbbVie. AbbVie contributed to the design, research, and interpretation of data, writing, reviewing, and approving the publication. NT, JZ, RM, BE, JW, SM, and SG are employees of AbbVie and may hold stock. AHW receives honoraria from Novartis, Astellas, Pfizer, Macrogenics, Abbvie, Genentech, Servier, Celgene, Amgen, Astra Zeneca and Janssen. AHW also receives research funding from Novartis, Celgene, Abbvie, Servier, Astra Zeneca and Amgen. AHW is a former employee of the Walter and Eliza Hall Institute and receives a fraction of its royalty stream related to venetoclax. G-GM is an investigator in AbbVie funded Clinical Trials. DM is a Genentech employee and may own stock. C.M. performed the analysis at AbbVie during an internship. C.M. also receives research funding from an industry consortium (AbbVie Deutschland GmbH & Co. KG, Boehringer Ingelheim Pharma GmbH & Co. KG, Grunenthal GmbH, F. Hoffmann-La Roche Ltd., Merck KGaA and Sanofi) for the PharMetrX program

Background: Venetoclax is a selective B-cell lymphoma-2 (BCL-2) inhibitor approved for use as monotherapy or with rituximab in patients with chronic lymphocytic leukemia (CLL). The objectives of the current analysis of observed data from adult patients randomized to venetoclax–rituximab in the phase III MURANO study were to characterize venetoclax pharmacokinetics (PKs) using a Bayesian approach, evaluate whether a previously developed population PK model for venetoclax can describe the PKs of venetoclax when administered with rituximab, and to determine post hoc estimates of PK parameters for the exposure–response analysis. Methods: Parameter estimates and uncertainty estimated by a population PK model were used as priors. Additional covariate effects (CLL risk status, geographic region, and 17p deletion [del(17p)] status) were added to the model. The updated model was used to describe venetoclax PKs after repeated dosing in combination with rituximab, and to determine post hoc estimates of PK parameters for exposure–response analysis. Results: The PK analysis included 600 quantifiable venetoclax PK samples from 182 patients in the MURANO study. Model evaluation using standard diagnostic plots, visual predictive checks, and normalized prediction distribution error plots indicated no model deficiencies. There was no significant relationship between venetoclax apparent clearance (CL/F) and bodyweight, age, sex, mild and moderate hepatic and renal impairment, or coadministration of weak cytochrome P450 3A inhibitors. The chromosomal abnormality del(17p) and CLL risk status had no apparent effect on the PKs of venetoclax. A minimal increase in venetoclax CL/F (approximately 7%) was observed after coadministration with rituximab. CL/F was 30% lower in patients from Central and Eastern Europe (n = 60) or Asia (n = 4) compared with other regions (95% confidence interval [CI] 21–39%). Apparent central volume of distribution was 30% lower (95% CI 22–38%) in females (n = 56) compared with males (n = 126). No clinically significant impact of region or sex was observed on key safety and efficacy outcomes. Conclusions: The Bayesian model successfully characterized venetoclax PKs over time and confirmed key covariates affecting PKs in the MURANO study. The model was deemed appropriate for further use in simulations and for generating individual patient PK parameters for subsequent exposure–response evaluation.

Exposure–response relationships from a phase 1b (M13-365) and phase 3 (MURANO) study were investigated to assess benefit/risk of venetoclax 400 mg daily plus rituximab in relapsed/refractory (R/R) chronic lymphocytic leukemia (CLL). Dose intensities were summarized by tertiles of predicted venetoclax steady-state average concentrations based on nominal venetoclax dose (CmeanSS,nominal) for tolerability; exposure–safety analyses used logistic regression. Exposure–progression-free survival (PFS) relationships were assessed using MURANO data, with CmeanSS,nominal as a grouping factor. Covariates were demographics, geographic region, study, baseline disease characteristics, ECOG performance status, responsiveness to prior therapy, and chromosomal abnormalities. There was no significant effect of covariates on grade ≥3 neutropenia/infection or PFS, and no relationship between venetoclax exposure and these endpoints, or venetoclax or rituximab dose intensity. These results support the recommended venetoclax 400 mg daily dose in combination with rituximab in patients with R/R CLL or small lymphocytic leukemia.

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.

Introduction: Venetoclax (VEN), an orally bioavailable selective BCL-2 inhibitor, was granted accelerated approval by the FDA for the treatment of acute myeloid leukemia (AML) in combination with a hypomethylating agent (HMA) or low-dose cytarabine (LDAC). The objective of this analysis was to characterize the exposure-efficacy and exposure-safety relationships using data from the nonrandomized Phase 1/2 studies and the confirmatory Phase 3 studies in subjects with treatment-naïve AML who are ineligible for intensive chemotherapy. Methods: A population pharmacokinetic (PK) model for VEN was characterized using data from 771 AML subjects across 5 Phase 1 - 3 studies including subjects with relapsed/refractory AML and subjects with treatment-naïve AML who were ineligible for intensive chemotherapy. PK parameters from this model were used to calculate the exposure metric, the area under the plasma concentration-time curve at steady-state (AUCss), for exposure-efficacy and exposure-safety analyses. Logistic regression and Cox proportional-hazards models were used to characterize the exposure-response relationships for overall survival, event-free survival, and conversion to post-baseline transfusion independence for red blood cells or platelets as well as key safety endpoints of treatment-emergent Grade ≥ 3 neutropenia, thrombocytopenia, and infections. Additionally, best overall response of complete remission (CR), CR + CR with incomplete blood count recovery (CRi), and CR + CR with partial hematological recovery (CRh) were also characterized in the exposure-response analyses. Separate analyses were performed for VEN + HMA and VEN + LDAC, including subjects taking placebo (PBO) + HMA or PBO + LDAC, respectively, to inform the intercepts. A total of 575 subjects with treatment-naïve AML were included in the exposure-response analyses for VEN + HMA and 279 subjects with treatment-naïve AML were included in the exposure-response analyses for VEN + LDAC. Results: VEN + HMA: For all efficacy endpoints studied, there was a clear trend for higher efficacy in subjects treated with VEN + HMA as compared to PBO in combination with azacitidine (AZA). When PBO patients were included, significant exposure-response relationships between VEN exposure and overall survival and event-free survival were identified, and a maximal effect (Emax) model best described the statistically significant positive relationships between VEN exposure and best overall response of CR + CRi and CR + CRh. However, there were no apparent relationships between VEN exposure and any efficacy endpoint without the inclusion of PBO subjects, suggesting that the beneficial effect of VEN is already maximized in the dose range studied (400 to 1200 mg daily [QD]). No exposure-response relationship was identified between VEN exposure and treatment-emergent Grade ≥ 3 thrombocytopenia or infections. An Emax model best described the statistically significant relationship between VEN exposure and treatment-emergent Grade ≥ 3 neutropenia, consistent with the clinical finding that subjects in the VEN + HMA treatment arms had higher rates of reported neutropenia than those in the PBO + AZA arm. VEN + LDAC: For all efficacy endpoints studied, there was a clear trend for higher efficacy in subjects treated with VEN + LDAC as compared to PBO + LDAC. With PBO subjects included, an Emax model best described the statistically significant relationships between VEN exposure and best overall response of CR, CR + CRi, and CR + CRh, with probability of response plateauing at exposures corresponding to 600 mg QD of VEN. There were no apparent relationships between VEN exposure and any efficacy endpoint when the PBO subjects were excluded from analysis, indicating that the beneficial effect of VEN is already maximized at 600 mg QD. Although reported rates of treatment-emergent Grade ≥ 3 neutropenia were higher in the VEN + LDAC treatment arms as compared to PBO + LDAC, no significant exposure-response relationships were found between VEN exposure and treatment-emergent Grade ≥ 3 neutropenia, thrombocytopenia, or infections. Conclusion: The VEN exposure-efficacy and exposure-safety analyses confirm the benefit of adding VEN to either HMA or LDAC and support the dose regimens of VEN 400 mg QD in combination with an HMA and VEN 600 mg QD in combination with LDAC in treatment-naïve AML patients who are ineligible for intensive chemotherapy. Disclosures Eckert: AbbVie Inc.: Current Employment, Other: may hold stock or other options. Brackman:AbbVie Inc.: Current Employment, Other: may hold stock or other options. Menon:AbbVie Inc.: Current Employment, Other: may hold stock or other options. Salem:AbbVie Inc.: Current Employment, Other: may hold stock or other options. Potluri:AbbVie: Current Employment, Other: may hold stock or stock options. Smith:Pfizer: Consultancy; Novartis: Consultancy; Celgene: Consultancy; Jazz Pharmaceuticals: Consultancy; Agios: Consultancy. Wei:AbbVie Inc.: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Astellas: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Research Funding; Amgen: Consultancy, Honoraria, Research Funding; MacroGenics: Consultancy, Honoraria; Servier: Consultancy, Honoraria, Research Funding; Walter and Eliza Hall Institute: Other: former employee and receives a fraction of its royalty stream related to venetoclax; Pfizer: Honoraria; Genentech: Honoraria; Astra Zeneca: Honoraria, Research Funding. Hayslip:Abbvie Inc: Current Employment, Other: may hold stock or other options. Miles:Genentech Inc.: Current Employment, Current equity holder in publicly-traded company. Mensing:AbbVie Inc.: Current Employment, Other: may hold stock or other options. Gopalakrishnan:AbbVie Inc.: Current Employment, Other: may hold stock or other options. Zha:AbbVie Inc.: Current Employment, Other: may hold stock or other options.

Purpose Cabozantinib is a multi-kinase inhibitor that targets MET, AXL, and VEGFR2, and may synergize with EGFR inhibition in NSCLC. Cabozantinib was assessed alone or in combination with erlotinib in patients with progressive NSCLC and EGFR mutations who had previously received erlotinib. Methods This was a phase Ib/II study (NCT00596648). The primary objectives of phase I were to assess the safety, pharmacokinetics, and pharmacodynamics and to determine maximum tolerated dose (MTD) of cabozantinib plus erlotinib in patients who failed prior erlotinib treatment. In phase II, patients with prior response or stable disease with erlotinib who progressed were randomized to single-agent cabozantinib 100 mg qd vs cabozantinib 100 mg qd and erlotinib 50 mg qd (phase I MTD), with a primary objective of estimating objective response rate (ORR). Results Sixty-four patients were treated in phase I. Doses of 100 mg cabozantinib plus 50 mg erlotinib, or 40 mg cabozantinib plus 150 mg erlotinib were determined to be MTDs. Diarrhea was the most frequent dose-limiting toxicity and the most frequent AE (87.5% of patients). The ORR for phase I was 8.2% (90% CI 3.3–16.5). In phase II, one patient in the cabozantinib arm (N = 15) experienced a partial response, for an ORR of 6.7% (90% CI 0.3–27.9), with no responses for cabozantinib plus erlotinib (N = 13). There was no evidence that co-administration of cabozantinib markedly altered erlotinib pharmacokinetics or vice versa. Conclusions Despite responses with cabozantinib/erlotinib in phase I, there were no responses in the combination arm of phase II in patients with acquired resistance to erlotinib. Cabozantinib did not appear to re-sensitize these patients to erlotinib. Electronic supplementary material The online version of this article (doi:10.1007/s00280-017-3283-z) contains supplementary material, which is available to authorized users.

Foretinib is an oral multi-kinase inhibitor targeting MET, vascular endothelial growth factor receptor (VEGFR)-2, RON, KIT, and AXL kinases. In this Phase 1, open-label, non-randomized study, foretinib was administered once daily at doses of 60 mg, 80 mg, 100 mg, or 120 mg for 28 days. The primary objectives were to determine the maximum tolerated dose (MTD) and assess the safety and tolerability of the daily oral administration schedule. Secondary objectives included pharmacokinetics, pharmacodynamics, and assessment of tumor response. Patients had histologically confirmed metastatic or unresectable solid tumors for which no standard treatments existed and all received oral foretinib once daily. Dose escalation was planned as a conventional "3+3" design with an expansion at the MTD for collection of additional safety and pharmacokinetic information. Thirty-seven patients were treated across four dose levels. The MTD was established as 80 mg foretinib. Dose-limiting toxicities were hypertension, dehydration, and diarrhea. The most common adverse events included fatigue, hypertension, nausea, and diarrhea. Twenty-three of 31 patients (74 %) had a best response of stable disease. No patient had a confirmed partial or complete response. At the MTD, steady state was achieved by approximately 2 weeks, with average post-dose time to maximum concentration, peak concentration, and trough concentration of 4 h, 46 ng/mL, and 24 ng/mL, respectively. In patients treated at the MTD, soluble MET and VEGF-A plasma levels significantly increased (P0.003) and soluble VEGFR2 plasma levels significantly decreased from baseline (P0.03). The MTD of foretinib bisphosphate salt was determined to be 80 mg once daily.

Purpose: Foretinib is an oral multikinase inhibitor targeting Met, RON, Axl, and vascular endothelial growth factor receptor. We conducted a phase I, first-time-in-human, clinical trial using escalating doses of oral foretinib. The primary objectives are to identify a maximum tolerated dose and determine the safety profile of foretinib. Secondary objectives included evaluation of plasma pharmacokinetics, long-term safety after repeated administration, preliminary antitumor activity, and pharmacodynamic activity. Experimental Design: Patients had histologically confirmed metastatic or unresectable solid tumors for which no standard measures exist. All patients received foretinib orally for 5 consecutive days every 14 days. Dose escalation followed a conventional “3+3” design. Results: Forty patients were treated in eight dose cohorts. The maximum tolerated dose was defined as 3.6 mg/kg, with a maximum administered dose of 4.5 mg/kg. Dose-limiting toxicities included grade 3 elevations in aspartate aminotransferase and lipase. Additional non–dose-limiting adverse events included hypertension, fatigue, diarrhea, vomiting, proteinuria, and hematuria. Responses were observed in two patients with papillary renal cell cancer and one patient with medullary thyroid cancer. Stable disease was identified in 22 patients. Foretinib pharmacokinetics increased linearly with dose. Pharmacodynamic evaluation indicated inhibition of MET phosphorylation and decreased proliferation in select tumor biopsies at submaximal doses. Conclusions: The recommended dose of foretinib was determined to be 240 mg, given on the first 5 days of a 14-day cycle. This dose and schedule were identified as having acceptable safety and pharmacokinetics, and will be the dose used in subsequent phase II trials. Clin Cancer Res; 16(13); 3507–16. ©2010 AACR.

To gain a better understanding of the mechanism of action of the metal cation–containing chemotherapeutic drug motexafin gadolinium (MGd), gene expression profiling analyses were conducted on plateau phase human lung cancer (A549) cell cultures treated with MGd. Drug treatment elicited a highly specific response that manifested in elevated levels of metallothionein isoform and zinc transporter 1 (ZnT1) transcripts. A549 cultures incubated with MGd in the presence of exogenous zinc acetate displayed synergistic increases in the levels of intracellular free zinc, metallothionein transcripts, inhibition of thioredoxin reductase activity, and cell death. Similar effects were observed in PC3 prostate cancer and Ramos B-cell lymphoma cell lines. Intracellular free zinc levels increased in response to treatment with MGd in the absence of exogenous zinc, indicating that MGd can mobilize bound intracellular zinc. These findings lead us to suggest that an important component of the anticancer activity of MGd is related to its ability to disrupt zinc metabolism and alter cellular availability of zinc. This class of compounds may provide insight into the development of novel cancer drugs targeting control of intracellular free zinc and the roles that zinc and other metal cations play in biochemical pathways relevant to cancer.

Purpose: This phase I, first-in-human study evaluated the safety, maximum-tolerated dose (MTD), pharmacokinetics, pharmacodynamics, and preliminary efficacy of SAR245409, an inhibitor of pan-Class I phosphoinositide 3-kinase (PI3K) and mTOR, administered orally once or twice daily in patients with advanced solid tumors. Experimental Design: Eighty-three patients received SAR245409. Doses ranged from 15 to 120 mg twice daily, and 70 to 100 mg once daily. A 3+3 dose-escalation design was used to determine the MTD. Patients were evaluated for adverse events and response. Assessments included pharmacokinetic, pharmacodynamic impact of SAR245409 on PI3K pathway signaling in hair sheath cells, skin and tumor, and characterization of tumor molecular alterations. Results: The MTDs were 50 mg twice daily and 90 mg once daily. The most frequent treatment-related adverse events were nausea (36.1%), diarrhea (21.7%), vomiting (19.3%), and decreased appetite (16.9%). The most frequent treatment-related grade 3/4 adverse events were increases in alanine aminotransferase (6.0%) and aspartate aminotransferase (4.8%). SAR245409 had a relatively short plasma half-life (2.96–7.52 hours). At MTDs, once- and twice-daily regimens yielded similar mean steady-state plasma exposure. A reduction in PI3K and mTORC1/mTORC2 pathway signaling was observed in serial hair sheath cells, skin, and tumor samples. Best response was stable disease in 48% of evaluable patients; seven patients had minor tumor regression. Twelve patients with stable disease were treated for ≥16 weeks. No trend was observed correlating tumor molecular alteration with antitumor activity. Conclusion: SAR245409 had a manageable safety profile, demonstrated reduced PI3K and mTORC1/mTORC2 pathway signaling and was associated with clinically relevant stable disease. Clin Cancer Res; 20(9); 2445–56. ©2014 AACR.

PURPOSE: Motexafin gadolinium is a magnetic resonance imaging (MRI)–detectable redox active drug that localizes selectively in tumor cells and enhances the effect of radiation therapy. This phase Ib/II trial of motexafin gadolinium, administered concurrently with 30 Gy in 10 fractions whole-brain radiation therapy (WBRT), was conducted to determine maximum-tolerated dose (MTD), dose-limiting toxicity, pharmacokinetics, and biolocalization in patients with brain metastases. Additional endpoints were radiologic response rate and survival. PATIENTS AND METHODS: Motexafin gadolinium was administered before each radiation treatment in this open-label, multicenter, international trial. In phase Ib, drug dose was escalated until the MTD was exceeded. In phase II, drug was evaluated in a narrow dose range. RESULTS: In phase Ib, the motexafin gadolinium dose was escalated in 39 patients (0.3 mg/kg to 8.4 mg/kg). In phase II, 22 patients received 5 mg/kg to 6.3 mg/kg motexafin gadolinium. Ten once-daily treatments were well tolerated. The MTD was 6.3 mg/kg, with dose-limiting reversible liver toxicity. Motexafin gadolinium’s tumor selectivity was established using MRI. The radiologic response rate was 72% in phase II. Median survival was 4.7 months for all patients, 5.4 months for recursive partitioning analysis (RPA) class 2 patients, and 3.8 months for RPA class 3 patients. One-year actuarial survival for all patients was 25%. CONCLUSION: Motexafin gadolinium was well tolerated at doses up to 6.3 mg/kg, was selectively accumulated in tumors, and, when combined with WBRT of 30 Gy in 10 fractions, was associated with a high radiologic response rate.

2565Background: PopPK and ER models were developed to characterize the C concentration-time profile and the relationship between C exposure and efficacy endpoints in pts with RCC. Methods: The PopP...

Background Sapphyrin analogues and related porphyrin-like species have attracted attention as anticancer agents due to their selective localization in various cancers, including hematologic malignancies, relative to surrounding tissues. Sapphyrins are electron affinic compounds that generate high yields of singlet oxygen formation. Although initially explored in the context of photodynamic therapy, sapphyrins have intrinsic anticancer activity that is independent of their photosensitizing properties. However, the mechanisms for their anticancer activity have not been fully elucidated. Results We have prepared a series of hydrophilic sapphyrins and evaluated their effect on proliferation, uptake, and cell death in adherent human lung (A549) and prostate (PC3) cancer cell lines and in an A549 xenograft tumor model. PCI-2050, the sapphyrin derivative with the highest in vitro growth inhibitory activity, significantly lowered 5-bromo-2'-deoxyuridine incorporation in S-phase A549 cells by 60% within eight hours and increased levels of reactive oxygen species within four hours. The growth inhibition pattern of PCI-2050 in the National Cancer Institute 60 cell line screen correlated most closely using the COMPARE algorithm with known transcriptional or translational inhibitors. Gene expression analyses conducted on A549 plateau phase cultures treated with PCI-2050 uncovered wide-spread decreases in mRNA levels, which especially affected short-lived transcripts. Intriguingly, PCI-2050 increased the levels of transcripts involved in RNA processing and trafficking, transcriptional regulation, and chromatin remodeling. We propose that these changes reflect the activation of cellular processes aimed at countering the observed wide-spread reductions in transcript levels. In our A549 xenograft model, the two lead compounds, PCI-2050 and PCI-2022, showed similar tumor distributions despite differences in plasma and kidney level profiles. This provides a possible explanation for the better tolerance of PCI-2022 relative to PCI-2050. Conclusion Hydrophilic sapphyrins were found to display promise as novel agents that localize to tumors, generate oxidative stress, and inhibit gene expression.

Foretinib is an oral multi-kinase inhibitor targeting MET, vascular endothelial growth factor receptor (VEGFR)-2, RON, KIT, and AXL kinases. In this Phase 1, open-label, non-randomized study, foretinib was administered once daily at doses of 60 mg, 80 mg, 100 mg, or 120 mg for 28 days. The primary objectives were to determine the maximum tolerated dose (MTD) and assess the safety and tolerability of the daily oral administration schedule. Secondary objectives included pharmacokinetics, pharmacodynamics, and assessment of tumor response. Patients had histologically confirmed metastatic or unresectable solid tumors for which no standard treatments existed and all received oral foretinib once daily. Dose escalation was planned as a conventional "3+3" design with an expansion at the MTD for collection of additional safety and pharmacokinetic information. Thirty-seven patients were treated across four dose levels. The MTD was established as 80 mg foretinib. Dose-limiting toxicities were hypertension, dehydration, and diarrhea. The most common adverse events included fatigue, hypertension, nausea, and diarrhea. Twenty-three of 31 patients (74 %) had a best response of stable disease. No patient had a confirmed partial or complete response. At the MTD, steady state was achieved by approximately 2 weeks, with average post-dose time to maximum concentration, peak concentration, and trough concentration of 4 h, 46 ng/mL, and 24 ng/mL, respectively. In patients treated at the MTD, soluble MET and VEGF-A plasma levels significantly increased (P

Sapphyrins are pentapyrrolic metal-free expanded porphyrins with potential medical use as anticancer agents. The novel sapphyrin derivative, PCI-2050, functionalized with 2-[2-(2-methoxyethoxy)ethoxy]ethoxy groups to enhance solubility and a modified bipyrrole moiety was found to be more potent in inducing apoptosis than the previously described sapphyrin PCI-2000. Because some sapphyrins may localize to tumors, we took advantage of the intrinsic fluorescence of these compounds to develop a flow cytometry–based assay to track sapphyrin biodistribution in tumor-bearing mice. Ex vivo analysis of sapphyrin-injected animals revealed that PCI-2050 preferentially localized to tumor, whereas PCI-2000 distributed into normal tissues rather than tumor. PCI-2050 uptake in xenograft tumor cells and resultant tumor cell cytotoxicity was dose dependent. To investigate structure–activity relationships, we focused on PCI-2050 and three derivatives that differ by their alkyl substituents on the bipyrrole moiety: PCI-2051, PCI-2052, and PCI-2053. Treatment of Ramos cells in culture or treatment of Ramos xenograft-bearing animals with each of the sapphyrins followed by ex vivo growth of tumor cells revealed the same pattern of cytotoxicity: PCI-2050 > PCI-2052 > PCI-2051 > PCI-2053. Thus, subtle changes in the alkyl substituents on the bipyrrole moiety result in significant changes in antitumor activity. PCI-2050 displayed significant antitumor efficacy in both Ramos and RKO xenograft models without hematologic, hepatic, or renal abnormalities as assessed by complete blood counts and serum chemistries. On the basis of these findings, it is concluded that the sapphyrin PCI-2050 warrants further evaluation as a potential anticancer agent due to its intrinsic proapoptotic activity and tumor localization ability. [Mol Cancer Ther 2006;5(11):2798–805]

Background Cabozantinib (cabo) is a potent oral therapy that inhibits MET, VEGFR2, and RET. In a phase 1 study, cabo demonstrated anti-tumor activity in patients with MTC, and a long terminal half-life of 120 hours. We report clinical activity and PK analyses from a Phase 3 study of cabo versus placebo (P) in patients with progressive, unresectable, locally advanced or metastatic MTC. Methods Patients with MTC and documented RECIST progression within 14 months (mo) of screening were randomized 2:1 to receive cabo (140 mg freebase qd, n = 219) or placebo (n = 111). Blood samples for PK were collected on days 1 and 29. Baseline tumor and blood samples were evaluated for RET mutation status. Tumor assessments occurred every 12 weeks, and the primary efficacy measure was progression-free survival (PFS), assessed by an independent radiology committee using RECIST. Results Statistically significant PFS prolongation was observed, with median PFS for cabo of 11.2 mo versus 4.0 mo for P (HR 0.28, 95% CI 0.19-0.40, p Conclusions Cabo significantly prolonged PFS compared to placebo in a patient population with progressive MTC. PK analysis supports administration of cabo as a fixed dose without adjustment for patient covariates. Disclosure M.J. Schlumberger: MJ Schlumberger has been a compensated consultant for Exelixis. M. Brose: Dr. Brose has received research funding and honoraria from Exelixis. M. Shah: Dr. Shah has received research funding from Exelixis. D.R. Miles: D. Miles is an employee and stockholder of Exelixis. L.T. Nguyen: Linh Nguyen is an employee and stockholder in Exelixis. S. Sherman: Dr. Sherman is a compensated consultant to Exelixis. All other authors have declared no conflicts of interest.

4504 Background: Cabozantinib (cabo) is an oral, potent inhibitor of MET and VEGFR2 that is currently undergoing evaluation in several oncology indications. Renal cell carcinoma (RCC) was chosen as an indication in this drug-drug interaction (DDI) study based on involvement of the MET and VEGFR signaling pathways in this disease. The primary objective of this study is to determine the effect of cabo on single dose PK of the CYP2C8 substrate rosiglitazone (rosi). Anti-tumor activity was also evaluated. Methods: Eligible pts were required to have RCC with clear cell components with metastases, Karnofsky performance status of ≥70 and measurable disease by RECIST. Pts needed to have experienced PD following standard therapies. Cabo was given daily at a dose of 140 mg free base (equivalent to 175 mg salt form) starting at Day 2. Rosi (4 mg) was given Day 1 and Day 22 to complete PK assessment for DDI. Cabo was continued until PD. On Day 57 and every 8 weeks thereafter subjects underwent tumor assessments by mRECIST. Results: Enrollment is complete at 25 RCC pts; 17/25 (64%) RCC pts had received ≥ 2 prior agents; 13/25 (52%) with at least 1 VEGF pathway inhibitor and 1 mTOR inhibitor. The majority of pts were in an intermediate (21/25) or poor (3/25) prognostic category (1/25 in favorable category) per Heng et al (JCO, 2009, v27, p5794). ORR by mRECIST: 7/25 (28%). Disease control rate (PR + SD): 72% at 16 weeks; 19/21 (90%) pts with ≥1 post-baseline scan experienced tumor regression (range: 4 - 63% reduction in measurements). 10/25 (36%) pts remain on cabo. Median PFS is 14.7 months (95% CI: 7.3, upper limit not reached) with a median follow-up of 7.7 months. AEs ≥ Grade 3 severity: hypophosphatemia (36%), hyponatremia (20%), and fatigue (16%). PK data suggest that clinically relevant doses of cabo do not alter the Cmax or AUC0-24h of rosi, consistent with no inhibition of CYP2C8. Conclusions: Cabo demonstrates encouraging anti-tumor activity in heavily pretreated RCC pts with a toxicity profile similar to that of other VEGFR TKIs. PK data suggest no DDI between cabo and rosi (CYP2C8 substrate).

5547 Background: Cabozantinib (cabo) is an oral, potent inhibitor of MET, VEGFR2, and RET that is currently undergoing evaluation in several oncology indications. Differentiated thyroid cancer (DTC) pts were included in this study based on involvement of the MET, VEGFR, and RET signaling pathways in this disease. The primary objective of this study is to determine the effect of cabo on single dose PK of the CYP2C8 substrate rosiglitazone (rosi). Anti-tumor activity and safety were also evaluated. Methods: Metastatic DTC pts who were enrolled to this study were required to be RAI-refractory, have progressed on standard therapies and have measurable disease. Cabo was given daily at a dose of 140 mg free base (equivalent to 175mg salt form) starting at Day 2. Rosi (4mg) was given Day 1 and Day 22 to complete PK assessment for drug-drug interaction (DDI). Cabo was continued until PD. On Day 57 and every 8 weeks thereafter subjects underwent tumor assessments by mRECIST. Results: 15 DTC pts were enrolled. Median number of prior regimens was 2 (11/15 pts had at least 1 prior VEGFR inhibitor). 8/15 pts (53%) had confirmed PRs including 1 pt with marked improvement of a bone infiltrating lesion; 6 (40%) had best response of SD; all 14 pts with ≥1 post-baseline scan experienced tumor regression (range: -9 to -55%). Disease control rate (PR + SD): 80% at 16 weeks; 10/15 (67%) remain on cabo with a median follow-up of 7.3 months. Median PFS and OS have not been reached. Most common Gr 3/4 AEs were: diarrhea (20%), lipase increased (20%), hypertension (13%) and palmar-plantar erythrodyesthesia (13%); one related Gr 5 event reported: hemoptysis due to aorto-trachael fistula in a pt with history of prior mediastinal XRT and extensive neck surgeries. PK data suggest that clinically relevant doses of cabo do not alter the Cmax or AUC0-24h of rosi, consistent with no inhibition of CYP2C8. Conclusions: In pts with DTC, cabo treatment resulted in substantial anti-tumor activity. The safety profile of cabo was comparable to that seen with other VEGFR TKIs. PK data suggest no DDI between cabo and rosi (CYP2C8 substrate).

364 Background: Cabozantinib (cabo) is an oral, potent inhibitor of MET and VEGFR2 that is currently undergoing clinical efficacy evaluation in several oncology indications. Renal cell carcinoma (RCC) was chosen as an indication in this drug-drug interaction (DDI) study based on involvement of the MET and VEGFR signaling pathways in this disease. The primary objective of this study is to determine the effect of cabo on single dose PK of the CYP2C8 substrate rosiglitazone (rosi). The exploratory objective of this study is to evaluate the preliminary antitumor activity of cabo in pts with RCC. Methods: Eligible pts were required to have RCC with clear cell components with metastases, Karnofsky performance status of ≥70 and measurable disease by RECIST. Pts needed to have experienced PD following standard therapies. Method for DDI study: Day 1, 4 mg rosi; Days 2 - 22, cabo given daily at a dose of 175 mg; Day 22, 4 mg rosi to complete PK assessment for DDI. Cabo continued until PD. On Day 57 and every 8 weeks thereafter subjects underwent tumor assessments by mRECIST. Results: Enrollment is complete at 25 RCC pts with a median of 2 prior regimens; 17/25 (68%) RCC pts had received ≥ 2 lines of prior therapy and 13/25 (52%) with at least 1 VEGF pathway inhibitor and 1 mTOR inhibitor. All pts were intermediate (24/25) or poor (1/25) risk category per Heng et al prognostic strata (JCO 2009). Related AEs ≥ Grade 3 severity: hypophosphatemia 8 (32%), PE 3 (12%; all were incidental / resolved) and diarrhea 3 (12%). Preliminary PK data suggest that clinically relevant doses of cabo do not markedly alter the Cmax or AUC0-24h of rosi consistent with lack of inhibition of CYP2C8. RCC pts with confirmed PR by mRECIST: 6/25 (24%). Additionally, 1 pt had an unconfirmed PR. Disease control rate (PR + SD): 68% at 16 weeks; 18/21 (86%) pts with ≥1 post-baseline scan experienced tumor regression (range: 4 – 63% reduction in measurements). 14/25 (56%) remain on cabo with a median follow-up of 4 months. Median PFS and OS have not been reached. Conclusions: Cabo demonstrates encouraging anti-tumor activity in heavily pretreated pts with RCC with a toxicity profile similar to that of other TKIs. Preliminary data suggest no DDI between cabo and rosi (CYP2C8 substrate).

Background: GDC 0973 is a potent, selective, orally administered MEK1/2 inhibitor. It has shown antitumor activity in preclinical models. A first-in-human, phase 1 dose escalation study in cancer patients was conducted using a 3+3 design with two dosing schedules, followed by an expansion at the MTD for each dosing schedule. The pharmacokinetic objective was to evaluate GDC-0973 PK in patients on both dosing schedules. Methods: GDC-0973 was administered orally, once daily on a 21 day on/7 day off (21/7) or on a 14 day on/14 day off (14/14) dosing schedule. Plasma samples for PK analysis were collected on Day 1 and Day 21 (for 21/7) or Day 14 (14/14) of Cycle 1, and during the dosing holiday to determine half-life of GDC-0973. Urine samples were collected on Day 1 and on Day 21 (21/7) or Day 14 (14/14) over a 24-hour period for exploratory analysis. Plasma samples were analyzed using a validated LC/MS/MS method. GDC-0973 pharmacokinetic data was analyzed using a non-compartmental approach with the program WinNonlin. Results: GDC-0973 pharmacokinetics was evaluated at doses administered in the 21/7 schedule (0.05, 0.1 and 0.2 mg/kg in a liquid solution and 10, 20, 40, 60, and 80 mg as capsules) and the 14/14 schedule (60, 80, 100 and 125 mg as capsules). Pharmacokinetic data was available in 41 patients on the 21/7 and 11 patients on the 14/14 schedule. GDC-0973 Cmax was observed at 1-4 hours post-dose, and was similar across the entire dose range. Cmax and AUC increased dose proportionally in the dose range up to 100 mg. The mean apparent oral clearance ranged from 4.30 to 11.7 L/h in the 0.05 mg/kg-100 mg dose range. The mean elimination half-life ranged from 31.6 to 53.5 hours in all dose levels in both schedules. Following daily oral dosing, the mean accumulation ratio was 2.0 to 4.0, which is consistent with its half-life and dosing interval, indicating that the PK was constant over time. Given the mean half-life of ∼40 hours, steady-state exposures are expected to be achieved in 8-10 days. Preliminary data suggest that approximately 1-8% of intact drug is excreted in urine; hence, renal excretion is a minor pathway for elimination. Exploratory analysis showed no clear association between exposure and demographic factors (age, weight, sex) or concomitant medications. PK was consistent between patients in the 21/7 and 14/14 dose escalation stages, as well as the expansion stages when compared at the same doses. Doses of 40 mg or higher in patients achieved steady-state concentrations consistent with antitumor activity observed in xenograft models. Conclusion: GDC-0973 preliminary PK analysis shows a moderate rate of absorption; with generally dose-proportional increases in Cmax and AUC. Updated data will be presented. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1304. doi:10.1158/1538-7445.AM2011-1304

Foretinib is a potent, orally available, small-molecule inhibitor of MET and VEGFR2. Significant tumor cell growth inhibition was observed preclinically following treatment in multiple tumor models. Antitumor activity was observed in a previous phase I study in which foretinib was dosed intermittently on days 1–5 every 14 days. This phase I dose-escalation study to evaluate daily oral administration of foretinib was conducted in adults with solid tumors. Foretinib was orally administered until disease progression or toxicity mandated removal from the study. Dose-limiting toxicities (DLTs) that occurred during the first 28 days of treatment were used to determine the maximum tolerated dose (MTD). Safety, tolerability, pharmacodynamics (PD), and pharmacokinetics (PK) were evaluated. Tumor volume was assessed every 8 weeks by RECIST. A total of 37 patients (pts) were treated across 4 dose levels in the following order: 60 mg/d (6 pts), 80 mg/d (12 pts), 120 mg/d (3 pts), 100 mg/d (3 pts), and 80 mg/d (13 pts, PK expansion). Reported DLTs were hypertension and dehydration at 120 mg/d and diarrhea at 100 mg/d. The MTD of foretinib was determined to be 80 mg. With chronic dosing, 12 of 25 pts (48%) on 80 mg required a dose reduction to 60 mg between 21 days and 4 months on treatment. Frequent AEs associated with foretinib were hypertension (62%), fatigue (51%), nausea (43%), diarrhea (41%), proteinuria (30%), increased lactate dehydrogenase (27%), vomiting (24%), anorexia (22%), increased aspartate transaminase (19%), rash (16%), increased GGT (16%), and increased lipase (16%), primarily CTCAE grades 1 and 2. The foretinib plasma PK (at MTD) was characterized by a tmax of ≈4 hours, a steady-state oral clearance (CL/F) of ≈83 L/h, and ≈3.8-fold accumulation at steady state (achieved by ≈day 15). At steady state, values of Cmax and AUC0–24 were ≈45.7 ng/mL and ≈805 h · ng/mL, respectively, and the Cmin was ≈52% of Cmax. Plasma PD markers were measured during cycle 1 in 19 pts treated at the MTD. Shed Met (sMET) and VEGF showed increases, whereas sVEGFR2 showed a decrease. No pts had confirmed partial response or complete response, but stable disease (SD) (range, 2.1–18.1 months) was seen in 23 pts (74.2%). 11 pts had tumor regression from baseline, with tumor shrinkage ranging from 1%–21%. Disease progression was seen in 8 pts (25.8%). Overall, 35.5% of pts were event-free at 6 months, and 12.9% of pts (diagnoses included medullary thyroid, hepatocellular, and papillary renal cell carcinomas, and alveolar soft part sarcoma) were event-free at 12 months. 62% percent of pts withdrew due to progressive disease, 8% due to AEs, 5% due to death, and 24% due to consent withdrawal/investigator discretion/other. Foretinib can be safely administered at the oral daily dose of 80 mg (MTD); however, with chronic administration, dose reductions were not uncommon. The safety profile observed with daily dosing of foretinib is similar to that seen with intermittent dosing. Plasma PK results indicate that exposure to foretinib was well maintained over the daily dosing interval. PD results are similar to that seen with intermittent dosing and indicate that sMET, VEGF, and sVEGFR2 are promising markers for monitoring biological activity of foretinib. Prolonged SD and tumor regression in pts with various cancers suggest that foretinib has promise as an anticancer therapy. Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A8.

3528 Background: XL647 is an orally bioavailable small molecule inhibitor of multiple receptor tyrosine kinases involved in tumorigenesis and angiogenesis, including EGFR/ErbB1, HER2/ErbB2 and VEGF...