Ribociclib plus Endocrine Therapy in Early Breast Cancer.

BACKGROUND: Ribociclib has been shown to have a significant overall survival benefit in patients with hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative advanced breast cancer. Whether this benefit in advanced breast cancer extends to early breast cancer is unclear. METHODS: In this international, open-label, randomized, phase 3 trial, we randomly assigned patients with HR-positive, HER2-negative early breast cancer in a 1:1 ratio to receive ribociclib (at a dose of 400 mg per day for 3 weeks, followed by 1 week off, for 3 years) plus a nonsteroidal aromatase inhibitor (NSAI; letrozole at a dose of 2.5 mg per day or anastrozole at a dose of 1 mg per day for ≥5 years) or an NSAI alone. Premenopausal women and men also received goserelin every 28 days. Eligible patients had anatomical stage II or III breast cancer. Here we report the results of a prespecified interim analysis of invasive disease-free survival, the primary end point; other efficacy and safety results are also reported. Invasive disease-free survival was evaluated with the use of the Kaplan-Meier method. The statistical comparison was made with the use of a stratified log-rank test, with a protocol-specified stopping boundary of a one-sided P-value threshold of 0.0128 for superior efficacy. RESULTS: As of the data-cutoff date for this prespecified interim analysis (January 11, 2023), a total of 426 patients had had invasive disease, recurrence, or death. A significant invasive disease-free survival benefit was seen with ribociclib plus an NSAI as compared with an NSAI alone. At 3 years, invasive disease-free survival was 90.4% with ribociclib plus an NSAI and 87.1% with an NSAI alone (hazard ratio for invasive disease, recurrence, or death, 0.75; 95% confidence interval, 0.62 to 0.91; P = 0.003). Secondary end points - distant disease-free survival and recurrence-free survival - also favored ribociclib plus an NSAI. The 3-year regimen of ribociclib at a 400-mg starting dose plus an NSAI was not associated with any new safety signals. CONCLUSIONS: Ribociclib plus an NSAI significantly improved invasive disease-free survival among patients with HR-positive, HER2-negative stage II or III early breast cancer. (Funded by Novartis; NATALEE ClinicalTrials.gov number, NCT03701334.).

Overall Survival with Ribociclib plus Letrozole in Advanced Breast Cancer.

BACKGROUND: In a previous analysis of this phase 3 trial, first-line ribociclib plus letrozole resulted in significantly longer progression-free survival than letrozole alone among postmenopausal patients with hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative advanced breast cancer. Whether overall survival would also be longer with ribociclib was not known. METHODS: Here we report the results of the protocol-specified final analysis of overall survival, a key secondary end point. Patients were randomly assigned in a 1:1 ratio to receive either ribociclib or placebo in combination with letrozole. Overall survival was assessed with the use of a stratified log-rank test and summarized with the use of Kaplan-Meier methods after 400 deaths had occurred. A hierarchical testing strategy was used for the analysis of progression-free survival and overall survival to ensure the validity of the findings. RESULTS: After a median follow-up of 6.6 years, 181 deaths had occurred among 334 patients (54.2%) in the ribociclib group and 219 among 334 (65.6%) in the placebo group. Ribociclib plus letrozole showed a significant overall survival benefit as compared with placebo plus letrozole. Median overall survival was 63.9 months (95% confidence interval [CI], 52.4 to 71.0) with ribociclib plus letrozole and 51.4 months (95% CI, 47.2 to 59.7) with placebo plus letrozole (hazard ratio for death, 0.76; 95% CI, 0.63 to 0.93; two-sided P = 0.008). No new safety signals were observed. CONCLUSIONS: First-line therapy with ribociclib plus letrozole showed a significant overall survival benefit as compared with placebo plus letrozole in patients with HR-positive, HER2-negative advanced breast cancer. Median overall survival was more than 12 months longer with ribociclib than with placebo. (Funded by Novartis; MONALEESA-2 ClinicalTrials.gov number, NCT01958021.).

Overall Survival with Ribociclib plus Fulvestrant in Advanced Breast Cancer.

BACKGROUND: In an earlier analysis of this phase 3 trial, ribociclib plus fulvestrant showed a greater benefit with regard to progression-free survival than fulvestrant alone in postmenopausal patients with hormone-receptor-positive, human epidermal growth factor receptor 2 (HER2)-negative advanced breast cancer. Here we report the results of a protocol-specified second interim analysis of overall survival. METHODS: Patients were randomly assigned in a 2:1 ratio to receive either ribociclib or placebo in addition to fulvestrant as first-line or second-line treatment. Survival was evaluated by means of a stratified log-rank test and summarized with the use of Kaplan-Meier methods. RESULTS: This analysis was based on 275 deaths: 167 among 484 patients (34.5%) receiving ribociclib and 108 among 242 (44.6%) receiving placebo. Ribociclib plus fulvestrant showed a significant overall survival benefit over placebo plus fulvestrant. The estimated overall survival at 42 months was 57.8% (95% confidence interval [CI], 52.0 to 63.2) in the ribociclib group and 45.9% (95% CI, 36.9 to 54.5) in the placebo group, for a 28% difference in the relative risk of death (hazard ratio, 0.72; 95% CI, 0.57 to 0.92; P = 0.00455). The benefit was consistent across most subgroups. In a descriptive update, median progression-free survival among patients receiving first-line treatment was 33.6 months (95% CI, 27.1 to 41.3) in the ribociclib group and 19.2 months (95% CI, 14.9 to 23.6) in the placebo group. No new safety signals were observed. CONCLUSIONS: Ribociclib plus fulvestrant showed a significant overall survival benefit over placebo plus fulvestrant in patients with hormone-receptor-positive, HER2-negative advanced breast cancer. (Funded by Novartis; MONALEESA-3 ClinicalTrials.gov number, NCT02422615.).

Overall Survival with Ribociclib plus Endocrine Therapy in Breast Cancer.

BACKGROUND: An earlier analysis of this phase 3 trial showed that the addition of a cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitor to endocrine therapy provided a greater benefit with regard to progression-free survival than endocrine therapy alone in premenopausal or perimenopausal patients with advanced hormone-receptor-positive, human epidermal growth factor receptor 2 (HER2)-negative breast cancer. Here we report the results of a protocol-specified interim analysis of the key secondary end point of overall survival. METHODS: We randomly assigned patients to receive either ribociclib or placebo in addition to endocrine therapy (goserelin and either a nonsteroidal aromatase inhibitor or tamoxifen). Overall survival was evaluated with the use of a stratified log-rank test and summarized with the use of Kaplan-Meier methods. RESULTS: A total of 672 patients were included in the intention-to-treat population. There were 83 deaths among 335 patients (24.8%) in the ribociclib group and 109 deaths among 337 patients (32.3%) in the placebo group. The addition of ribociclib to endocrine therapy resulted in significantly longer overall survival than endocrine therapy alone. The estimated overall survival at 42 months was 70.2% (95% confidence interval [CI], 63.5 to 76.0) in the ribociclib group and 46.0% (95% CI, 32.0 to 58.9) in the placebo group (hazard ratio for death, 0.71; 95% CI, 0.54 to 0.95; P = 0.00973 by log-rank test). The survival benefit seen in the subgroup of 495 patients who received an aromatase inhibitor was consistent with that in the overall intention-to-treat population (hazard ratio for death, 0.70; 95% CI, 0.50 to 0.98). The percentage of patients who received subsequent antineoplastic therapy was balanced between the groups (68.9% in the ribociclib group and 73.2% in the placebo group). The time from randomization to disease progression during receipt of second-line therapy or to death was also longer in the ribociclib group than in the placebo group (hazard ratio for disease progression or death, 0.69; 95% CI, 0.55 to 0.87). CONCLUSIONS: This trial showed significantly longer overall survival with a CDK4/6 inhibitor plus endocrine therapy than with endocrine therapy alone among patients with advanced hormone-receptor-positive, HER2-negative breast cancer. No new concerns regarding toxic effects emerged with longer follow-up. (Funded by Novartis; MONALEESA-7 ClinicalTrials.gov number, NCT02278120.).

Buparlisib and paclitaxel in patients with platinum-pretreated recurrent or metastatic squamous cell carcinoma of the head and neck (BERIL-1): a randomised, double-blind, placebo-controlled phase 2 trial.

BACKGROUND: Phosphatidylinositol 3-kinase (PI3K) pathway activation in squamous cell carcinoma of the head and neck contributes to treatment resistance and disease progression. Buparlisib, a pan-PI3K inhibitor, has shown preclinical antitumour activity and objective responses in patients with epithelial malignancies. We assessed whether the addition of buparlisib to paclitaxel improves clinical outcomes compared with paclitaxel and placebo in patients with recurrent or metastatic squamous cell carcinoma of the head and neck. METHODS: In this multicentre, randomised, double-blind, placebo-controlled phase 2 study (BERIL-1), we recruited patients aged 18 years and older with histologically or cytologically confirmed recurrent and metastatic squamous cell carcinoma of the head and neck after disease progression on or after one previous platinum-based chemotherapy regimen in the metastatic setting. Eligible patients were enrolled from 58 centres across 18 countries and randomly assigned (1:1) to receive second-line oral buparlisib (100 mg once daily) or placebo, plus intravenous paclitaxel (80 mg/m2 on days 1, 8, 15, and 22) in 28 day treatment cycles. Randomisation was done via a central patient screening and randomisation system with an interactive (voice and web) response system and stratification by number of previous lines of therapy in the recurrent and metastatic setting and study site. Patients and investigators (including local radiologists) were masked to treatment assignment from randomisation until the final overall survival analysis. The primary endpoint was progression-free survival by local investigator assessment per Response Evaluation Criteria In Solid Tumors (version 1.1) in all randomly assigned patients. Efficacy analyses were done on the intention-to-treat population, whereas safety was analysed in all patients who received at least one dose of study drug and had at least one post-baseline safety assessment according to the treatment they received. This trial is registered with ClinicalTrials.gov, number NCT01852292, and is ongoing but no longer enrolling patients. FINDINGS: Between Nov 5, 2013, and May 5, 2015, 158 patients were enrolled and randomly assigned to receive either buparlisib plus paclitaxel (n=79) or placebo plus paclitaxel (n=79). Median progression-free survival was 4·6 months (95% CI 3·5-5·3) in the buparlisib group and 3·5 months (2·2-3·7) in the placebo group (hazard ratio 0·65 [95% CI 0·45-0·95], nominal one-sided p=0·011). Grade 3-4 adverse events were reported in 62 (82%) of 76 patients in the buparlisib group and 56 (72%) of 78 patients in the placebo group. The most common grade 3-4 adverse events (occurring in ≥10% of patients in the buparlisib group vs the placebo group) were hyperglycaemia (17 [22%] of 76 vs two [3%] of 78), anaemia (14 [18%] vs nine [12%]), neutropenia (13 [17%] vs four [5%]), and fatigue (six [8%] vs eight [10%]). Serious adverse events (regardless of relation to study treatment) were reported for 43 (57%) of 76 patients in the buparlisib group and 37 (47%) of 78 in the placebo group. On-treatment deaths occurred in 15 (20%) of 76 patients in the buparlisib group and 17 (22%) of 78 patients in the placebo group; most were caused by disease progression and none were judged to be related to study treatment. INTERPRETATION: On the basis of the improved clinical efficacy with a manageable safety profile, the results of this randomised phase 2 study suggest that buparlisib in combination with paclitaxel could be an effective second-line treatment for patients with platinum-pretreated recurrent or metastatic squamous cell carcinoma of the head and neck. Further phase 3 studies are warranted to confirm this phase 2 finding. FUNDING: Novartis Pharmaceuticals Corporation.

Patient subgroup identification for clinical drug development.

Causal mechanism of relationship between the clinical outcome (efficacy or safety endpoints) and putative biomarkers, clinical baseline, and related predictors is usually unknown and must be deduced empirically from experimental data. Such relationships enable the development of tailored therapeutics and implementation of a precision medicine strategy in clinical trials to help stratify patients in terms of disease progression, clinical response, treatment differentiation, and so on. These relationships often require complex modeling to develop the prognostic and predictive signatures. For the purpose of easier interpretation and implementation in clinical practice, defining a multivariate biomarker signature in terms of thresholds (cutoffs/cut points) on individual biomarkers is preferable. In this paper, we propose some methods for developing such signatures in the context of continuous, binary and time-to-event endpoints. Results from simulations and case study illustration are also provided. Copyright © 2017 John Wiley & Sons, Ltd.

Methodology for Good Machine Learning with Multi-Omics Data.

In 2020, Novartis Pharmaceuticals Corporation and the U.S. Food and Drug Administration (FDA) started a 4-year scientific collaboration to approach complex new data modalities and advanced analytics. The scientific question was to find novel radio-genomics-based prognostic and predictive factors for HR+/HER- metastatic breast cancer under a Research Collaboration Agreement. This collaboration has been providing valuable insights to help successfully implement future scientific projects, particularly using artificial intelligence and machine learning. This tutorial aims to provide tangible guidelines for a multi-omics project that includes multidisciplinary expert teams, spanning across different institutions. We cover key ideas, such as "maintaining effective communication" and "following good data science practices," followed by the four steps of exploratory projects, namely (1) plan, (2) design, (3) develop, and (4) disseminate. We break each step into smaller concepts with strategies for implementation and provide illustrations from our collaboration to further give the readers actionable guidance.

Quantitative Assessment of Ribociclib Exposure-Response Relationship to Justify Dose Regimen in Patients with Advanced Breast Cancer.

Ribociclib in combination with endocrine therapy (ET) is a globally approved treatment option for patients with hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2-) advanced breast cancer (ABC) and has demonstrated significantly improved overall survival (OS) in 3 phase 3 clinical trials. To justify the dose regimen and dose modification scheme for patients with ABC, the pharmacokinetic (PK), safety, and efficacy data of ribociclib were analyzed. The data of several phase 1-3 clinical studies were pooled and analyzed to characterize the relationship between exposure (dose or PK) and efficacy (progression-free survival (PFS), time to response, and OS) or safety (neutropenia and QT interval prolongation). The exposure-efficacy analysis showed no apparent relationship between ribociclib exposure and efficacy (PFS and OS), and efficacy analysis by dose reduction showed that patients with ABC continued to benefit from the treatment following dose reduction, supporting the starting dose of 600 mg as well as dose reductions to 400 and 200 mg. The exposure-safety analysis showed that neutropenia and QT prolongation are related to ribociclib exposure that can be effectively managed by individualized dose modification (dose reduction/interruption). Collective evidence from the exposure-response analyses for efficacy and safety support the use of ribociclib in combination with ET partners at the starting dose of 600 mg, and also the effectiveness of individualized dose reductions in managing safety, while maintaining efficacy, in patients with HR+/HER2- ABC. This analysis illustrates the utility of quantitative assessment in justifying dose selection and dose modification for oncology medicines.

Rationale and trial design of NATALEE: a Phase III trial of adjuvant ribociclib + endocrine therapy versus endocrine therapy alone in patients with HR+/HER2- early breast cancer.

Background: Ribociclib has demonstrated a statistically significant overall survival benefit in pre- and postmenopausal patients with hormone receptor positive/human epidermal growth factor receptor 2 negative (HR+/HER2-) advanced breast cancer. New Adjuvant Trial with Ribociclib [LEE011] (NATALEE) is a trial evaluating the efficacy and safety of adjuvant ribociclib plus endocrine therapy (ET) versus ET alone in patients with HR+/HER2- early nonmetastatic breast cancer (EBC). Methods/design: NATALEE is a multicenter, randomized, open-label, Phase III trial in patients with HR+/HER2- EBC. Eligible patients include women, regardless of menopausal status, and men aged ⩾18 years. Select patients with stage IIA, stage IIB, or stage III disease (per the anatomic classification in the AJCC Cancer Staging Manual, 8th edition) with an initial diagnosis ⩽18 months prior to randomization are eligible. Patients receiving standard (neo)adjuvant ET are eligible if treatment was initiated ⩽12 months before randomization. Patients undergo 1:1 randomization to ribociclib 400 mg/day (3 weeks on/1 week off) +ET (letrozole 2.5 mg/day or anastrozole 1 mg/day [investigator's discretion] plus goserelin [men or premenopausal women]) or ET alone. Ribociclib treatment duration is 36 months; ET treatment duration is ⩾60 months. The primary end point is invasive disease-free survival. Discussion: The 36-month treatment duration of ribociclib in NATALEE is extended compared with that in other adjuvant cyclin-dependent kinases 4 and 6 (CDK4/6) inhibitor trials and is intended to maximize efficacy due to longer duration of CDK4/6 inhibition. Compared with the 600-mg/day dose used in advanced breast cancer, the reduced ribociclib dose used in NATALEE may improve tolerability while maintaining efficacy. NATALEE includes the broadest population of patients with HR+/HER2- EBC of any Phase III trial currently evaluating adjuvant CDK4/6 inhibitor treatment. Trial registration: ClinicalTrials.gov identifier: NCT03701334 (https://clinicaltrials.gov/ct2/show/NCT03701334).

Updated Overall Survival of Ribociclib plus Endocrine Therapy versus Endocrine Therapy Alone in Pre- and Perimenopausal Patients with HR+/HER2- Advanced Breast Cancer in MONALEESA-7: A Phase III Randomized Clinical Trial.

PURPOSE: Ribociclib plus endocrine therapy (ET) demonstrated a statistically significant progression-free survival and overall survival (OS) benefit in the phase III MONALEESA-7 trial of pre-/perimenopausal patients with hormone receptor (HR)-positive (HR+), HER2-negative (HER2-) advanced breast cancer (ABC). The median OS was not reached in the ribociclib arm in the protocol-specified final analysis; we hence performed an exploratory OS and additional outcomes analysis with an extended follow-up (median, 53.5 months). PATIENTS AND METHODS: Patients were randomized to receive ET [goserelin plus nonsteroidal aromatase inhibitor (NSAI) or tamoxifen] with ribociclib or placebo. OS was evaluated with a stratified Cox proportional hazard model and summarized with Kaplan-Meier methods. RESULTS: The intent-to-treat population included 672 patients. Median OS was 58.7 months with ribociclib versus 48.0 months with placebo [hazard ratio = 0.76; 95% confidence interval (CI), 0.61-0.96]. Kaplan-Meier estimated OS at 48 months was 60% and 50% with ribociclib and placebo, respectively. Subgroup analyses were generally consistent with the OS benefit, including patients who received NSAI and patients aged less than 40 years. Subsequent antineoplastic therapies following discontinuation were balanced between the ribociclib (77%) and placebo (78%) groups. Use of cyclin-dependent kinase 4/6 inhibitors after discontinuation was higher with placebo (26%) versus ribociclib (13%). Time to first chemotherapy was significantly delayed with ribociclib versus placebo. No drug-drug interactions were observed between ribociclib and either NSAI. CONCLUSIONS: Ribociclib plus ET continued to show significantly longer OS than ET alone in pre-/perimenopausal patients, including patients aged less than 40 years, with HR+/HER2- ABC with 53.5 months of median follow-up (ClinicalTrials.gov, NCT02278120).

Phase Ib dose-finding study of abiraterone acetate plus buparlisib (BKM120) or dactolisib (BEZ235) in patients with castration-resistant prostate cancer.

BACKGROUND: The phosphatidylinositol-3-kinase (PI3K)/protein kinase B (Akt) signalling axis and androgen receptor (AR) pathways exhibit reciprocal feedback regulation in phosphatase and tensin homologue (PTEN)-deficient metastatic castration-resistant prostate cancer (CRPC) in preclinical models. This phase Ib study evaluated the pan-PI3K inhibitor buparlisib (BKM120) and the dual pan-PI3K/ mammalian target of rapamycin (mTOR) inhibitor dactolisib (BEZ235) in combination with abiraterone acetate (AA) in patients with CRPC. MATERIALS AND METHODS: Patients with CRPC who had progressed on AA therapy received escalating doses of either buparlisib or dactolisib, along with fixed doses of AA (1000 mg once daily (qd)) and prednisone (5 mg twice daily (bid)). The primary objective was to define the maximum tolerated dose (MTD) and/or the recommended dose for expansion (RDE) of either buparlisib or dactolisib in combination with AA. Secondary objectives included safety, antitumour activity (Prostate Cancer Working Group 2 (PCWG2) criteria; 30% of prostate-specific antigen (PSA) decline at ≥week 12) and pharmacokinetic (PK) profile. RESULTS: In buparlisib + AA arm, 25 patients received buparlisib + AA (median age, 67 years; Eastern Cooperative Oncology Group performance status (ECOG PS) of 0/1/2 for 7/17/1 patients, respectively). At 100 mg qd; two patients experienced dose-limiting toxicities (DLTs) (grade 3 hyperglycaemia; grade 2 asthenia), and this was the maximum buparlisib dose explored. Buparlisib + AA showed a 26% lower median area under the curve from time zero to 24°h (AUC0-24) and 48% lower median maximum serum concentration (Cmax) versus the single-agent buparlisib assessed in first-in-human study. No objective response and few PSA decreases were reported. In dactolisib + AA arm, 18 patients (median age, 71 years; ECOG PS of 0/1 for 6/12 patients, respectively) received dactolisib + AA at the first dose level (200 mg bid). Five patients had 9 DLTs (grades 2&3 stomatitis; grade 3 hyperglycaemia; grades 2& 3 diarrhoea; grades 1& 2 pyrexia, grade 2 vomiting, and grade 2 chills). CONCLUSIONS: Based on the assessment of available pharmacokinetics, safety, and efficacy data, no further study is planned for either buparlisib or dactolisib in combination with AA in CRPC.

Plasma biomarker signature associated with improved survival in advanced non-small cell lung cancer patients on linifanib.

OBJECTIVES: Linifanib, a potent and selective inhibitor of the tyrosine kinase activity of vascular endothelial growth factor and platelet-derived growth factor receptors, has clinical activity in advanced non-small cell lung cancer (NSCLC) both as monotherapy in the relapsed setting or with carboplatin and paclitaxel in the first-line setting. Though benefit was observed in unselected patient populations, identification of predictive biomarkers is critical for further development of this novel agent. MATERIALS AND METHODS: Data from 4 randomized studies in relapsed NSCLC with linifanib (n=116) or other treatments (n=125) were examined in an exploratory analysis to identify a biomarker profile predictive of favorable survival. RESULTS: A signature combining the established tumor markers carcinoembryonic antigen (CEA) and cytokeratin 19 fragments (CYFRA 21-1) was predictive of a favorable outcome. This signature was associated with improved survival in patients receiving linifanib monotherapy (hazard ratio [HR]=0.51 vs signature negative; p=0.002), but not in those receiving other anti-cancer treatments (p=0.716). This signature was validated on baseline plasma samples from patients enrolled in a randomized trial of daily linifanib 7.5 mg, linifanib 12.5 mg, or placebo added to first-line carboplatin and paclitaxel chemotherapy for advanced, nonsquamous NSCLC. Only linifanib-treated signature-positive patients had significant improvement in progression-free survival (PFS). Median PFS with placebo was 5.2 months versus 10.2 months (HR=0.49, p=0.049) for those receiving linifanib 7.5mg, and 8.3 months (HR=0.38, p=0.029) for linifanib 12.5 mg. Overall survival for signature-positive patients was 11.3 months with placebo, 12.5 months with linifanib 7.5mg (HR=1.02, p=0.758), and 17.4 months with linifanib 12.5 mg (HR=0.54, p=0.137). CONCLUSION: This baseline plasma biomarker signature is associated with improved outcome in advanced NSCLC patients receiving linifanib. Utility of the biomarker signature in patient selection for linifanib therapy in NSCLC merits evaluation in larger, prospective trials that are powered to detect a survival benefit.

A novel multi-targeted tyrosine kinase inhibitor, linifanib (ABT-869), produces functional and structural changes in tumor vasculature in an orthotopic rat glioma model.

Tyrosine kinase inhibitors represent a class of targeted therapy that has proven to be successful for cancer treatment. Linifanib is a novel, orally active multi-targeted receptor tyrosine kinase (RTK) inhibitor that exhibits potent antitumor and antiangiogenic activities against a broad spectrum of experimental tumors and malignancies in patients. The compound is currently being evaluated in phase 2 and 3 clinical trials. To investigate the effectiveness of linifinib against gliomas and the mechanism of drug action, we characterized treatment-induced antitumor and antiangiogenic responses to linifanib in an orthotopic rat glioma model. The effect of linifanib treatment on tumor growth was determined by tumor volume assessment using anatomical magnetic resonance imaging (MRI). Changes in tumor microvessel function were evaluated with dynamic contrast-enhanced MRI (DCE-MRI). Immunohistochemistry (IHC) was applied to excised tumor samples to examine underlying changes in vascular structures and target receptor expression. Linifanib (10 mg/kg) given twice daily inhibited tumor growth following treatment for 7 days with tumor volumes being 149 ± 30 and 66 ± 7 mm(3) for vehicle-and linifanib-treated groups, respectively. A significant reduction of 37 ± 13% in tumor perfusion and microvessel permeability (measured by K (trans)) was observed as early as 2 h after administration compared with vehicle treatment. Continuous linifanib administration further reduced K (trans) at later time points until the end of the study (7 days post-treatment). At day 7, K (trans) was reduced by 75 ± 32% for linifanib treatment compared with vehicle treatment. Significant reduction in total blood vessel density and improved vessel wall integrity were observed, and staining for target receptor expression confirmed inhibition of phospho VEGFR-2 and PDGFR-ß by linifanib treatment. These results demonstrate significant antitumor and antiangiogenic activity against gliomas by linifanib, a property that may result from the inhibition of VEGFR-2 and PDGFR-ß-mediated vascular changes. DCE-MRI measured K (trans) changes at early treatment stages may be a useful pharmacodynamic marker for linifanib activity in clinical trials, and basal K (trans) may provide predictive value for tumor progression.

Pharmacodynamic evaluation of irinotecan therapy by FDG and FLT PET/CT imaging in a colorectal cancer xenograft model.

PURPOSE: Longitudinal changes of 3'-[(18) F]fluoro-3'-deoxythymidine (FLT) and 2-deoxy-2-[(18) F]fluoro-D-glucose (FDG) in response to irinotecan therapy in an animal model of colorectal cancer were compared. PROCEDURES: SCID/CB-17 mice with HCT116 tumors were treated with 50 mg/kg irinotecan by intraperitoneal injection weekly for 3 weeks. FLT and FDG-positron emission tomography (PET) were performed at baseline, the day after each treatment, and 5 days after the first treatment. Proliferation and apoptosis were evaluated by immunohistochemistry (IHC) after day 15 of imaging. RESULTS: Irinotecan treatment resulted in a suppression of tumor growth. Tumor FLT uptake was decreased the day after each treatment but to a lesser extent 5 days after the first treatment. FDG uptake increased the day after each treatment with a continuous increase throughout the experiment. IHC analysis of phospho-H3 and Ki67 confirmed FLT-PET results, indicating a decrease in proliferation the day after the final irinotecan treatment. Increased apoptosis monitored by caspase-3 was observed after day 15 with irinotecan treatment. CONCLUSIONS: FLT-PET may be a better method than FDG-PET for assessing treatment response to irinotecan. Changes in imaging occur before changes in tumor volume.

Phase II study of single-agent navitoclax (ABT-263) and biomarker correlates in patients with relapsed small cell lung cancer.

PURPOSE: Bcl-2 is a critical regulator of apoptosis that is overexpressed in the majority of small cell lung cancers (SCLC). Nativoclax (ABT-263) is a potent and selective inhibitor of Bcl-2 and Bcl-x(L). The primary objectives of this phase IIa study included safety at the recommended phase II dose and preliminary, exploratory efficacy assessment in patients with recurrent and progressive SCLC after at least one prior therapy. EXPERIMENTAL DESIGN: Thirty-nine patients received navitoclax 325 mg daily, following an initial lead-in of 150 mg daily for 7 days. Study endpoints included safety and toxicity assessment, response rate, progression-free and overall survival (PFS and OS), as well as exploratory pharmacodynamic correlates. RESULTS: The most common toxicity associated with navitoclax was thrombocytopenia, which reached grade III-IV in 41% of patients. Partial response was observed in one (2.6%) patient and stable disease in 9 (23%) patients. Median PFS was 1.5 months and median OS was 3.2 months. A strong association between plasma pro-gastrin-releasing peptide (pro-GRP) level and tumor Bcl-2 copy number (R = 0.93) was confirmed. Exploratory analyses revealed baseline levels of cytokeratin 19 fragment antigen 21-1, neuron-specific enolase, pro-GRP, and circulating tumor cell number as correlates of clinical benefit. CONCLUSION: Bcl-2 targeting by navitoclax shows limited single-agent activity against advanced and recurrent SCLC. Correlative analyses suggest several putative biomarkers of clinical benefit. Preclinical models support that navitoclax may enhance sensitivity of SCLC and other solid tumors to standard cytotoxics. Future studies will focus on combination therapies.

Phenotypic fingerprinting of small molecule cell cycle kinase inhibitors for drug discovery.

Phenotypic drug discovery, primarily abandoned in the 1980's in favor of targeted approaches to drug development, is once again demonstrating its value when used in conjunction with new technologies. Phenotypic discovery has been brought back to the fore mainly due to recent advances in the field of high content imaging (HCI). HCI elucidates cellular responses using a combination of immunofluorescent assays and computer analysis which increase both the sensitivity and throughput of phenotypic assays. Although HCI data characterize cellular responses in individual cells, these data are usually analyzed as an aggregate of the treated population and are unable to discern differentially responsive subpopulations. A collection of 44 kinase inhibitors affecting cell cycle and apoptosis were characterized with a number of univariate, bivariate, and multivariate subpopulation analyses demonstrating that each level of complexity adds additional information about the treated populations and often distinguishes between compounds with seemingly similar mechanisms of action. Finally, these subpopulation data were used to characterize compounds as they relate in chemical space.