Comparative in Vitro Cellular Data Alone Is Insufficient to Predict Clinical Responses and Guide Choice of BCR-ABL Inhibitor to Treat Imatinib-Resistant Chronic Myeloid Leukemia.

Abstract Abstract 510 Background: Recently, Redaelli et al (J Clin Oncol. 2009;27:469) compared the in vitro inhibitory activity of imatinib, dasatinib, nilotinib, and bosutinib against 18 mutant forms of BCR-ABL (expressed in transfected Ba/F3 cells) associated with imatinib resistance and proposed a chart to assist in the selection of second-generation tyrosine kinase inhibitors (2TKIs) for the treatment of imatinib-resistant CML associated with mutations. However, the predictability of this chart has neither been clinically evaluated nor does it take into account other important clinical factors (e.g. pharmacokinetics (PK)/pharmacodynamics) that may impact response rates to 2TKIs in the presence of mutations. The purpose was to assess the impact of 2TKIs' in vivo plasma levels on the in vitro GI50 data, and to determine if in vitro GI50 data with or without plasma levels correlates with observed clinical responses in imatinib-resistant patients (pts) with mutations. Methods: To enable appropriate comparison of the activity of 2TKIs against specific mutations we modified the original in vitro GI50 data by adjusting it to include an estimate of in vivo Cmax exposure data for each 2TKI. Further refinement was achieved by calculating the Cmax/GI50 values for each agent and normalizing these against imatinib vs wild-type BCR-ABL. To assess the correlation between patient response and in vitro GI50 data, the previously published CCyR rates for pts with specific mutations were plotted according to in vitro GI50 values alone and against the adjusted Cmax/GI50 values. Results: The adjusted Cmax/GI50 data suggest that nilotinib delivers the most potent inhibition of most BCR-ABL mutations in vivo, with dasatinib being the next most potent. However, when either in vitro GI50 data alone or the modified Cmax/GI50 data are considered, there is poor correlation of clinical responses to both nilotinib and dasatinib against several of the mutations in vivo (Figure). Overall, activity of 2TKIs against all mutations was less than expected based on original in vitro GI50 or Cmax/GI50 calculations of systemic exposure. For example, the G250E mutation has similar systemic exposure to nilotinib as the F359V mutation as indicated by Cmax/GI50, but substantial differences are observed in the CCyR rate (60% vs 0%). For dasatinib, the same was observed for the F317L and L248V mutations which have similar exposures to dasatinib but have different CCyR rates (7% vs 41%). Similarly, several mutations with comparable exposure to nilotinib and dasatinib had substantial differences in CCyR rates, suggesting that other factors were influencing responses. For example, the G250E mutation was considered moderately sensitive to both nilotinib and dasatinib based on the adjusted Cmax/GI50; however, CCyR rates on nilotinib were much higher (60%) compared with dasatinib (34%). Similarly, the E255K mutation was considered moderately sensitive to both agents based on the adjusted Cmax/GI50; however, CCyR rates on dasatinib were much higher (38%) compared with nilotinib (13%). Conclusions: This analysis illustrates the limitations of in vitro inhibition data alone or in combination with PK exposure data in the selection of 2TKI therapy for imatinib-resistant pts with mutations. The current analysis still does not consider parameters such as protein binding and intracellular influx/efflux, among a variety of other clinical factors that could further influence response rates. This tool is also not useful for pts with mutations of unknown in vitro sensitivity, which may represent 15% of all pts with mutations. Currently, clinical responses remain the best approach for selection of 2TKIs in pts with mutations, with only a small subset of mutations having low sensitivity mutations existing for each 2TKI. Other factors, such as patient medical history, comorbidities, and the agents' safety profiles, are also important in selection of 2TKIs. Disclosures: Laneuville: Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Bristol-Myers Squibb: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Wyeth: Research Funding; ChemGenex: Research Funding. DiLea:Novartis: Employment. Mestan:Novartis: Employment. Yin:Novartis: Employment, Equity Ownership. Woodman:Novartis: Employment. Manley:Novartis: Employment. </jats:sec

Using pharmacokinetic and pharmacodynamic data in early decision making regarding drug development: a phase I clinical trial evaluating tyrosine kinase inhibitor, AEE788.

PURPOSE: In this first-in-human study of AEE788, a tyrosine kinase inhibitor of epidermal growth factor receptor (EGFR), HER-2, and VEGFR-2, a comprehensive pharmacodynamic program was implemented in addition to the evaluation of safety, pharmacokinetics, and preliminary efficacy of AEE788 in cancer patients. EXPERIMENTAL DESIGN: Patients with advanced, solid tumors received escalating doses of oral AEE788 once daily. Primary endpoints were to determine dose-limiting toxicities (DLTs) and maximum-tolerated dose (MTD). A nonlinear model (Emax model) was used to describe the relationship between AEE788 exposure and target-pathway modulation in skin and tumor tissues. RESULTS: Overall, 111 patients were treated (25 to 550 mg/day). DLTs included rash and diarrhea; MTD was 450 mg/day. Effects on biomarkers correlated to serum AEE788 concentrations. The concentration at 50% inhibition (IC(50)) for EGFR in skin (0.033 μmol/L) and tumor (0.0125 μmol/L) were similar to IC(50) in vitro suggesting skin may be surrogate tissue for estimating tumor EGFR inhibition. No inhibition of p-MAPK and Ki67 was observed in skin vessels at ≤ MTD. Hence, AEE788 inhibited EGFR, but not VEGFR, at doses ≤ MTD. A total of 16 of 96 evaluable patients showed a >10% shrinkage of tumor size; one partial response was observed. CONCLUSION: Our pharmacodynamic-based study showed effective inhibition of EGFR, but not of VEGFR at tolerable AEE788 doses. Emax modeling integrated with biomarker data effectively guided real-time decision making in the early development of AEE788. Despite clinical activity, target inhibition of only EGFR led to discontinuation of further AEE788 development

Phase Ib Study of the Novel Anti-CXCR4 Antibody Ulocuplumab (BMS-936564) in Combination with Lenalidomide Plus Low-Dose Dexamethasone, or with Bortezomib plus Dexamethasone in Subjects with Relapsed or Refractory Multiple Myeloma

Abstract Background: CXCR4 is a chemokine receptor over-expressed on &gt; 75% of cancers, including malignant plasma cells. Ulocuplumab (BMS- 936564) is a first in class, fully human IgG4 monoclonal anti-CXCR4 antibody which inhibits the binding of CXCR4 to CXCL12. Ulocuplumab induces apoptosis of CXCR4+ multiple myeloma cell lines and has single agent activity in vivo in MM tumor xenograft models. It is thus hypothesized that Ulocuplumab may improve the overall response rate to standard therapy in relapsed-refractory multiple myeloma (rel/ref MM) by distinct mechanisms of action, i.e., mobilization and apoptosis of malignant plasma cells and immune regulation. Objective:This study aimed to determine the safety, tolerability, pharmacokinetics, pharmacodynamics and clinical activity of Ulocuplumab alone and in combination with lenalidomide plus low-dose dexamethasone (Len-Dex), or in combination with bortezomib plus dexamethasone (Bor-Dex) in subjects with rel/ref MM. Methods: Ulocuplumab (i.e., 1, 3 and 10 mg/kg) was dose escalated with a 3-plus-3 design with doses of Len-Dex orBor-Dex to identify MTD. For Cycle 1, Ulocuplumab was administered as monotherapy on Days 1 and 8. Starting on Day 15, Ulocuplumab was administered in combination with lenalidomide [25 mg/d/21 days of a 28 day cycle] plus low dose dexamethasone [40 mg/week] and monitored for incidence of DLT(s) within Cycle 1 (42 Days) of study treatment. For the Bor-Dex group, also starting on Day 15, Ulocuplumab was administered in combination with bortezomib (1.3 mg/m2Days 1, 4, 8, 11 of a 21 day cycle] plus dexamethasone [days 1,2,4,5,8,9,11,12] and monitored for incidence of DLT(s) within Cycle 1 (35 Days) of study treatment. For the expansion phase, subjects received 10mg/kg Ulocuplumab monotherapy on Days 1 and 8 followed by weekly doses in combination with Len-Dex (28-day cycles). Subjects were assessed at day 14 and after every cycle by IMWG criteria. Results: Forty four subjects were evaluated (median age, 59.5 yrs; range, 44-77). The median number of prior therapies was 4, (range, 1-9), with 76% of subjects having received ≥ 3. Subjects had received bortezomib in 93% of the cases, lenalidomide in 86% , thalidomide in 30%, carfilzomib in 20% and pomalidomide in 11%. Thirty subjects in escalation received Ulocuplumab alone and in combination with Len-Dex : One subject in the U-Bor-Dex group experienced a DLT in which there was delayed platelet recovery to ≤ Grade 1 or baseline which resulted in a delay of dosing of ≥ 21 days. Ulocuplumab was escalated to a maximum of 10 mg/kg without reaching MTD in monotherapy or in combination therapy. Twenty one subjects were treated in expansion phase. There were no grade 4 toxicities with Ulocuplumab monotherapy and Grade 3 toxicities with monotherapy included thrombocytopenia (6.5%), anemia (4.3%), respiratory infections (4.3%), femur fracture (4.3%), lymphopenia (2.2%), neutrophil count decreased (2.2%), platelet count decreased (2.2%) and cerebrovascular accident (2.2%). The safety profile of Ulocuplumab with Len-Dex or Bor-Dex was similar to either combination alone. Two subjects (4.5%) presented reversible G2 infusion reactions. The overall response rate (≥ PR) for all subjects in escalation and expansion was 50% (22/44), including 1 CR, 6 VGPR and 15 PR. The ORR by group was 55.1 % (16/29) and 40% (6/15) for U-Len-Dex and U-Bor-Dex, respectively. Furthermore, the ORR in expansion with 10 mg/kg U-Len-Dex was 57% (12/21) with 4 VGPRs and 8 PRs. Eight subjects in this expansion group had at least SD with a mean duration of 159 days (range, 46-437 days), resulting in 95% of subjects with clinical benefit. A median 2-fold mobilization of leukocytes into the peripheral circulation was reported after each infusion of Ulocuplumab at 3 and 10 mg/kg. Samples showed rapid mobilization of leukocytes at 2 hours post-Ulocuplumab with a partial decrease at 3-4 days post-administration without reaching baseline. Mobilization of plasma cells was also documented in some subjects. Conclusions: This study shows that the blockade of the CXCR4-CXCL12 axis by Ulocuplumab is safe and shows a high response rate of over 50% in the Len-dex arm of patients with relapsed/refractory myeloma who have been previously treated with lenalidomide and bortezomib. The distinct mechanisms of action of this antibody make it a new class of anti-myeloma drug that deserves further exploration in clinical trials. Disclosures Ghobrial: Onyx: Advisory board Other; BMS: Advisory board, Advisory board Other, Research Funding; Noxxon: Research Funding; Sanofi: Research Funding; Millennium: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees. Off Label Use: Plerixafor is not FDA approved for relapsed myeloma. Anderson:Celgene: Consultancy; Sanofi-Aventis: Consultancy; Onyx: Consultancy; Acetylon: Scientific Founder, Scientific Founder Other; Oncoprep: Scientific Founder Other; Gilead Sciences: Consultancy. Sabbatini:Bristol-Myers Squibb: Employment. Dilea:Bristol-Myers Squibb: Employment. Cardarelli:BMS: Employment. Wade:Bristol-Myers Squibb: Employment. Xing:Bristol-Myers Squibb: Employment. Gutierrez:Bristol-Myers Squibb: Employment. Cohen:BMS: Employment. </jats:sec