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Supplementary Figure 2 PDF file - 91K, Speed of recovery of downstream targets in NCI-N87

Supplementary Table 1 PDF file - 69K, NVP-AUY922 IC50 concentrations and response to trastuzumab in HER2 amplified breast cancer cell lines

Supplementary Legends PDF file - 78K, Supplementary Figure Legends

PDF - 69K, Supplemental Figure Legend

Heat shock protein 90 (HSP90) is involved in protein folding and functions as a chaperone for numerous client proteins, many of which are important in non–small cell lung cancer (NSCLC) pathogenesis. We sought to define preclinical effects of the HSP90 inhibitor NVP-AUY922 and identify predictors of response. We assessed in vitro effects of NVP-AUY922 on proliferation and protein expression in NSCLC cell lines. We evaluated gene expression changes induced by NVP-AUY922 exposure. Xenograft models were evaluated for tumor control and biological effects. NVP-AUY922 potently inhibited in vitro growth in all 41 NSCLC cell lines evaluated with IC50 < 100 nmol/L. IC100 (complete inhibition of proliferation) < 40 nmol/L was seen in 36 of 41 lines. Consistent gene expression changes after NVP-AUY922 exposure involved a wide range of cellular functions, including consistently decreased dihydrofolate reductase after exposure. NVP-AUY922 slowed growth of A549 (KRAS-mutant) xenografts and achieved tumor stability and decreased EGF receptor (EGFR) protein expression in H1975 xenografts, a model harboring a sensitizing and a resistance mutation for EGFR-tyrosine kinase inhibitors in the EGFR gene. These data will help inform the evaluation of correlative data from a recently completed phase II NSCLC trial and a planned phase IB trial of NVP-AUY922 in combination with pemetrexed in NSCLCs. Mol Cancer Ther; 12(6); 890–900. ©2013 AACR.

PDF - 769K, Heat maps from microarray analyses of gene expression changes seen in at least 13 of 16 experiments after exposure to NVP-AUY922

Supplementary Figure 3 PDF file - 58K, Activation of HSP70 in both N87-Parental and N87-TRC cell lines

PDF - 47B, A tabular demonstration of the efficacy and tolerability of NVP-AUY922 in 32 mice carrying subcutaneous A549 or H1975 xenograft tumors randomized

Supplementary Table 1. Baseline characteristics Supplementary Table 2. Criteria for defining dose-limiting toxicities.

Purpose: A phase I study was conducted with the primary objective of determining the maximum tolerated dose (MTD) of AUY922 in patients with advanced solid tumors. Secondary objectives included characterization of the safety, pharmacokinetic, and pharmacodynamic profiles.Patients and Methods: Patients with advanced solid tumors received 1-hour i.v. infusions of AUY922 once a week in a 28-day cycle. An adaptive Bayesian logistic regression model that employed observed dose-limiting toxicities (DLT) in the first treatment cycle was used to guide dose-escalation decisions, with the established MTD to be used in phase II studies.Results: One hundred and one patients were enrolled and explored at doses in the range of 2 to 70 mg/m2. DLTs occurred in 8 patients (22–70 mg/m2) and included diarrhea, asthenia/fatigue, anorexia, atrial flutter, and visual symptoms. At 70 mg/m2, the AUY922 concentration achieved was consistent with active concentrations in a range of xenograft models. There was evidence of target inhibition in peripheral blood mononuclear cells (HSP70 induction) and tumor (client protein depletion and reduction of metabolic activity by 18F-FDG PET). The recommended phase II dose (RP2D) of 70 mg/m2 was proposed on the basis of toxicity and pharmacokinetic and pharmacodynamic profiles.Conclusions: At the RP2D of 70 mg/m2, AUY922 exhibited acceptable tolerability, and phase II single-agent and combination studies have been initiated in patients with HER2-positive breast, gastric, and non–small cell lung cancers. Clin Cancer Res; 19(13); 3671–80. ©2013 AACR.

This phase I study aimed to determine tolerability and preliminary efficacy of single-agent alpelisib (BYL719) in Japanese patients with advanced solid malignancies. The primary objective of the study was to estimate the maximum tolerated dose (MTD) and/or recommended phase II dose (RP2D) of oral alpelisib in patients with advanced solid tumors who had progressed despite standard therapy. The expansion part included patients with PIK3CA mutation/amplification; safety, preliminary efficacy, pharmacokinetic (PK)/pharmacodynamic profile, and food effect on the PK profile of alpelisib at the MTD/RP2D were determined. Oral alpelisib was given as a single agent on a continuous 28-day treatment cycle once daily. Overall, 33 patients received alpelisib. Dose-limiting toxicities were observed in 2 patients in the escalation part (at 400 mg/day) and 1 patient in the expansion part (at 350 mg/day). The RP2D of alpelisib was determined as 350 mg/day based on overall safety profile in the dose escalation part and previous data from a Western population; the MTD was not determined. The most common all-grade treatment-suspected adverse events were hyperglycemia and maculopapular rash (48.5% each) and diarrhea (45.5%). The PK of alpelisib in the Japanese population was similar to that reported in the Western population. The overall response rate, disease control rate, and median progression-free survival at 350 mg/day were 3%, 57.6%, and 3.4 months, respectively. Alpelisib as single agent showed a favorable safety profile and encouraging preliminary efficacy in Japanese patients with advanced solid tumors.

Purpose BEZ235 is a dual kinase inhibitor of phosphatidylinositol 3-kinase (PI3K) and mammalian target of rapamycin, which are key components of the PI3K pathway. This was an open-label, multicenter, dose-escalation, phase I study of single-agent BEZ235 in Japanese oncology patients to determine the maximum tolerated dose (MTD) of BEZ235 based on dose-limiting toxicities (DLTs). Methods Dose escalation was guided by a standard 3 + 3 method and was based on DLTs observed in Cycle 1 and other safety, pharmacokinetic, and pharmacodynamic information. A total of 35 adult Japanese patients with advanced solid tumors received BEZ235 according to once daily (qd; n = 27) or twice daily (bid; n = 8) dosing schedules. Results Two DLTs, namely, allergic reaction and thrombocytopenia, were observed at 1200 and 1400 mg qd, respectively, while liver dysfunction was reported as a DLT at 400 mg bid. The most common adverse events suspected to be related to BEZ235 in both dosing schedules were diarrhea, nausea, decreased appetite, stomatitis, and thrombocytopenia. Conclusions Although the MTD was not established, the maximum clinically tolerable dose was determined to be 1200 mg because two out of six patients required dose reduction in Cycle 2. The recommended dose was determined to be 1000 mg qd, which was comparable with the results of the first-in-human BEZ235 study in Western patients with advanced solid tumors (NCT00620594). Additionally, the tolerability of BEZ235 400 mg bid in Japanese oncology patients was confirmed in this study. ClinicalTrials.gov identifier NCT01195376. Electronic supplementary material The online version of this article (10.1007/s00280-018-3725-2) contains supplementary material, which is available to authorized users.

1054 Background: PIK3CA mutations, present in ̃40% of HR+, HER2– ABC, are associated with therapeutic resistance and shorter survival. Alpelisib (ALP) + fulvestrant (FUL) demonstrated efficacy in this population for which achieving long-term (LT) disease control is challenging. Here, we report on pts with HR+, PIK3CA-altered ABC who achieved LT disease control with ALP + FUL. Methods: SOLAR-1 was a phase 3, randomized, double-blind study of ALP (or placebo) + FUL in HR+, HER2– ABC that progressed on/after an aromatase inhibitor. CBYL719X2101 (X2101) was a phase 1, open-label study of escalating ALP doses ± FUL in advanced solid tumors that progressed on/after anti-estrogen therapy (ET) or relapsed after adjuvant anti-ET. A cut-off ≥ median (progression-free survival [PFS] + 2 SE) was chosen based on Kaplan-Meier curves from SOLAR-1 to define LT disease control as PFS (SOLAR-1) or time on treatment (X2101) ≥18 mo. Results: In SOLAR-1, 51 of 169 pts (30.2%) randomized to ALP + FUL achieved LT disease control with a median PFS of 33.5 mo (95% CI, 27.4 mo-not reached). Baseline characteristics of pts in SOLAR-1 are in the table below. In pts with LT disease control, adverse events (AEs) of special interest (combined preferred terms) of GI toxicity were observed in 47 pts (92.2%; grade ≥3: 11.8%, n=6), of hyperglycemia in 41 pts (80.4%; grade ≥3: 39.2%, n=20), and of rash in 28 pts (54.9%; grade ≥3: 19.6%, n=10). Median ALP relative dose intensity was 79.9% and 82.1% for pts with LT disease control (n=51) and the overall population (n=168), respectively. In X2101, 7 of 52 pts (13.5%) with ABC who received ALP+FUL achieved LT disease control up to 47.8 mo. Conclusions: In this subset of pts with hard-to-treat, endocrine-resistant disease, LT disease control ≥18 mo is meaningful considering median PFS of 4.6-9.3 mo or 9.5-16.4 mo with FUL alone or with cyclin-dependent kinase 4/6 inhibitors, respectively. Here, LT disease control was observed in 2 studies of HR+, PIK3CA-altered ABC, including in pts with poor prognosis, diabetes/pre-diabetes at baseline, and heavy pre-treatment. AE profile was consistent with prior reports and did not preclude LT disease control. Further work is needed to better understand factors influencing LT disease control. Clinical trial information: NCT01219699, NCT02437318 .[Table: see text]

Background: CSF-1R signaling regulates the function of tumor-associated macrophages (TAMs) which are poor prognostic indicators in several cancers. In animal models, including intracranial GBM, M-CSF/CSF-1 blockade may reduce TAM recruitment to the tumor microenvironment, inhibit tumor growth, and overcome resistance to PD-1 inhibitors. BLZ945, a highly selective brain penetrant CSF-1R kinase inhibitor, is being explored as single agent and with the anti-PD-1 mAb, spartalizumab. Here we present dose-escalation results from a Phase I/II, open-label study of BLZ945 ± spartalizumab (NCT02829723). Methods: Pts aged ≥18 years with advanced/metastatic solid tumors including GBM, received BLZ945 Q1W (300 mg-1600 mg QD and 600 mg BID), 7d on/7d off (150 mg-300 mg QD), or 4d on/10d off (300 mg-1200 mg QD and 600 mg BID); or BLZ945 Q1W (150 mg-1400 mg QD, 600 mg-800 mg BID) or 4d on/10d off (300 mg-1200 mg QD) + spartalizumab (400 mg IV, Q4W). Phase I objective was to characterize safety, tolerability, antitumor activity and pharmacokinetics (PK) of BLZ945 ± spartalizumab and determine the MTDs and/or RP2Ds using an adaptive Bayesian logistic regression model with overdose control, and considering overall safety including control of ALT/AST, PK, and clinical efficacy. Results: We report 146 pts receiving BLZ945 (77 pts) or the combination (69 pts), 57/43% M/F, median age 57.5 years. DLTs occurred in 7/77 pts in the BLZ945 arm (increases in amylase, lipase, AST, ALP, worsening of elevated amylase, sudden death) and 7/69 pts in the combination arm (increases in amylase, AST, ALT, dizziness, hyperuricemia). Treatment-related AEs (TRAEs) (≥20%) were AST increase (35%), nausea (29%) and vomiting (23%) in the BLZ945 arm and AST increase (38%), ALT increase (25%), vomiting (23%), and nausea (20%) in the combination arm. Gr ≥3 TRAEs were reported in 19/77 (25%) pts in the BLZ945 arm and 23/69 (33%) pts in the combination arm. Median duration of exposure (DOE) was 8 weeks for BLZ945 alone (1.0-66.6) and for the combination (2.1-85.0). BLZ945 half-life was 15hr-24hr, exposure increases were less than dose proportional after 600/700 mg. BLZ945 did not affect spartalizumab PK and vice versa. Overall response assessment (RECIST 1.1) showed a partial response in 1 pt with HNSCC in the combination arm; stable disease was observed in 21/61 (34%) and 22/49 (45%) pts in the BLZ945 and combination arms, respectively. In evaluable pts with relapsed/refractory GBM (n=18: 7 BLZ945 arm, 11 combination arm), 2 partial responses were reported per RANO (1 per arm). Among treated pts with GBM (n=24), the median DOE was 8 weeks, with 7/24 (29%) pts on treatment for >16 weeks. Conclusions: BLZ945 ± spartalizumab showed an acceptable safety pattern; RP2D was declared as 1200 mg (4d on/10d off) for single-agent BLZ945, the MTD was 700 mg (4d on/10d off) for BLZ945 + spartalizumab. Encouraging preliminary antitumor activity was observed in pts with GBM. Citation Format: Chia-Chi Lin, Marta Gil-Martin, Todd M. Bauer, Aung Naing, Darren Wan-Teck Lim, John Sarantopoulos, Ravit Geva, Yuichi Ando, Liqiong Fan, Somesh Choudhury, Pei-Jung Tu, Cornelia Quadt, Armando Santoro. Phase I study of BLZ945 alone and with spartalizumab (PDR001) in patients (pts) with advanced solid tumors [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr CT171.

Background: The colony stimulating factor 1 receptor (CSF-1R) signaling pathway promotes tumor progression via the recruitment, differentiation, and survival of immuno-suppressive tumor-associated macrophages (TAMs). Blocking CSF-1R signaling may lead to the depletion of TAMs and increased T-cell activation. BLZ945 is an oral, highly selective and potent kinase inhibitor of CSF-1R, which can cross the blood-brain barrier. By reducing TAMs and promoting a pro-inflammatory microenvironment, BLZ945 may stimulate T-cell responses, thereby sensitizing solid tumors to anti–PD-1 therapy. Methods: BLZ945X2101 is an ongoing Ph I/II study investigating the use of BLZ945 as single agent and in combination with spartalizumab (anti–PD-1) in advanced solid tumors. Eligible pts (aged ≥18 years, ECOG 0–1) with advanced/metastatic solid tumors received BLZ945 (300 mg–1600 mg QD and 600 mg BID) Q1W, 7d on/7d off (150 mg–300 mg QD), or 4d on/10d off (300 mg–1200 mg QD and 600 mg BID); or BLZ945 (150 mg–1400 mg QD, 600 mg–800 mg BID) Q1W or 4d on/10d off (300 mg–1200 mg) plus spartalizumab at a fixed dose of 400 mg IV, Q4W. Baseline and on-treatment tumor samples were collected. Here we report flow cytometric, soluble ligand and gene expression profiling analyses as evidence of on-target pharmacodynamic effects of BLZ945 + spartalizumab in treated patients. Results: In total, paired samples for 61 pts for flow cytometry, samples from 30 pts for CSF-1 plasma and paired samples from 35 pts for RNAseq analysis were analyzed. BLZ945 (+/-spartalizumab) induced increases in plasma CSF-1 and decreased peripheral intermediate and nonclassical monocytes, at all doses and schedules tested. Gene expression profiling by RNAseq in paired biopsies showed downregulation of macrophage associated genes in patients treated with both single-agent BLZ945 and BLZ945 + spartalizumab. In patients treated with the BLZ945 + spartalizumab combination, upregulation of cytokine, chemokine, and HLA genes was observed. Signs of antitumor activity were observed in several tumor types including glioblastoma and head and neck cancer. Conclusions: Flow cytometric, soluble ligand and gene expression profiling demonstrated BLZ945-mediated CSF-1R blockade in the periphery and tumor microenvironment in patients with advanced cancers. Ongoing analyses include identification of transcriptomic signatures associated with response. These data support further clinical development of BLZ945 ± spartalizumab in advanced cancers (NCT02829723). Citation Format: Jincheng Wu, Chia-Chi Lin, Marta Gil-Martin, Aung Naing, Liqiong Fan, Fang Yang, David Quinn, Pei-Jung Tu, Cornelia Quadt, Jennifer Mataraza. Pharmacodynamic and gene expression profiling of patients treated with BLZ945 + spartalizumab demonstrates on-target peripheral and tumor immune microenvironment modulation [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr CT172.

Importance The phosphatidylinositol 3-kinase (PI3K) pathway is frequently activated in patients with estrogen receptor–positive (ER+), endocrine therapy–resistant breast cancers. Objective To assess the maximum tolerated dose (MTD), safety, and activity of alpelisib, an oral, PI3Kα-specific inhibitor, plus fulvestrant in patients with ER+ advanced breast cancer (ABC). Design, Setting, and Participants An open-label, single-arm, phase 1b study of alpelisib plus fulvestrant was conducted at 10 centers in 5 countries. Participants were 87 postmenopausal women with PIK3CA-altered or PIK3CA-wild-type ER+ ABC, whose cancer progressed during or after antiestrogen therapy. The study began enrolling patients October 5, 2010, and the data cutoff was March 22, 2017. Interventions Escalating doses of alpelisib were administered once daily, starting at 300 mg, plus fixed-dose fulvestrant, 500 mg, in the dose-escalation phase; alpelisib at the recommended phase 2 dose plus fulvestrant in the dose-expansion phase. Main Outcomes and Measures The primary end point was determination of the MTD of once-daily alpelisib plus fulvestrant. Secondary end points included safety and preliminary activity. Results From October 5, 2010, to March 22, 2017, 87 women (median age: 58 years [range, 37-79 years]; median of 5 prior lines of antineoplastic therapy) received escalating once-daily doses of alpelisib (300 mg, n = 9; 350 mg, n = 8; 400 mg, n = 70) plus fixed-dose fulvestrant (500 mg). During dose escalation, dose-limiting toxic effects were reported in 1 patient (alpelisib, 400 mg): diarrhea (grade 2), vomiting, fatigue, and decreased appetite (all grade 3). The MTD of alpelisib when combined with fulvestrant was 400 mg once daily, and the recommended phase 2 dose was 300 mg once daily. Overall, the most frequent grade 3/4 adverse events with alpelisib, 400 mg, once daily (≥10% of patients), regardless of causality, were hyperglycemia (19 [22%]) and maculopapular rash (11 [13%]); 9 patients permanently discontinued therapy owing to adverse events. Median progression-free survival at the MTD was 5.4 months (95% CI, 4.6-9.0 months). Median progression-free survival with alpelisib, 300 to 400 mg, once daily plus fulvestrant was longer in patients with PIK3CA-altered tumors (9.1 months; 95% CI, 6.6-14.6 months) vs wild-type tumors (4.7 months; 95% CI, 1.9-5.6 months). Overall response rate in the PIK3CA-altered group was 29% (95% CI, 17%-43%), with no objective tumor responses in the wild-type group. Conclusions and Relevance Alpelisib plus fulvestrant has a manageable safety profile in patients with ER+ ABC, and data suggest that this combination may have greater clinical activity in PIK3CA-altered vs wild-type tumors.

Purpose We report the first-in-human phase Ia study to our knowledge ( ClinicalTrials.gov identifier: NCT01219699) identifying the maximum tolerated dose and assessing safety and preliminary efficacy of single-agent alpelisib (BYL719), an oral phosphatidylinositol 3-kinase α (PI3Kα)–selective inhibitor. Patients and Methods In the dose-escalation phase, patients with PIK3CA-altered advanced solid tumors received once-daily or twice-daily oral alpelisib on a continuous schedule. In the dose-expansion phase, patients with PIK3CA-altered solid tumors and PIK3CA-wild-type, estrogen receptor–positive/human epidermal growth factor receptor 2–negative breast cancer received alpelisib 400 mg once daily. Results One hundred thirty-four patients received treatment. Alpelisib maximum tolerated doses were established as 400 mg once daily and 150 mg twice daily. Nine patients (13.2%) in the dose-escalation phase had dose-limiting toxicities of hyperglycemia (n = 6), nausea (n = 2), and both hyperglycemia and hypophosphatemia (n = 1). Frequent all-grade, treatment-related adverse events included hyperglycemia (51.5%), nausea (50.0%), decreased appetite (41.8%), diarrhea (40.3%), and vomiting (31.3%). Alpelisib was rapidly absorbed; half-life was 7.6 hours at 400 mg once daily with minimal accumulation. Objective tumor responses were observed at doses ≥ 270 mg once daily; overall response rate was 6.0% (n = 8; one patient with endometrial cancer had a complete response, and seven patients with cervical, breast, endometrial, colon, and rectal cancers had partial responses). Stable disease was achieved in 70 (52.2%) patients and was maintained > 24 weeks in 13 (9.7%) patients; disease control rate (complete and partial responses and stable disease) was 58.2%. In patients with estrogen receptor–positive/human epidermal growth factor receptor 2–negative breast cancer, median progression-free survival was 5.5 months. Frequently mutated genes (≥ 10% tumors) included TP53 (51.3%), APC (23.7%), KRAS (22.4%), ARID1A (13.2%), and FBXW7 (10.5%). Conclusion Alpelisib demonstrated a tolerable safety profile and encouraging preliminary activity in patients with PIK3CA-altered solid tumors, supporting the rationale for selective PI3Kα inhibition in combination with other agents for the treatment of PIK3CA-mutant tumors.

PURPOSE: To determine the maximum tolerated dose (MTD) of BEZ235, an oral inhibitor of class I PI3K and mTOR complexes 1 and 2. METHODS: We performed a phase I/Ib, multicenter, open-label study of oral BEZ235 administered in a continuous daily schedule. The study consisted of two parts: dose-escalation part and safety-expansion part. BEZ235 was administered as a single agent to patients with solid tumors or in combination with trastuzumab for HER2+ advanced breast cancer (aBC). Primary end points were MTD, safety, and tolerability. The secondary end point was pharmacokinetics. Other formulations of BEZ235, solid dispersion system (SDS) sachet, and SDS capsules were also assessed. RESULTS: One hundred and eighty-three patients were enrolled; single-agent BEZ235 was administered as hard gelatin capsule (n = 59), SDS capsules A and B (n = 33), and SDS sachet (n = 61), amongst which SDS sachet was chosen as the preferred formulation. The monotherapy MTD for capsule A and SDS sachet was determined to be 1000 and 1200 mg/day, respectively. Thirty patients with HER2+ aBC received BEZ235 in combination with trastuzumab. The MTD of BEZ235 in combination with trastuzumab was 600 mg/day. A total of four patients (13.3%) achieved partial response across the different groups. Most frequent AEs in single agent and combination cohorts included nausea (80.3 and 93.3%), diarrhea (75.4 and 80.0%), and vomiting (63.9 and 63.3%). CONCLUSIONS: The MTD of BEZ235 as single agent was 1200 and 600 mg/day with trastuzumab. Pharmacokinetic profiles showed low-to-moderate variability at low dose (10 mg) and high variability at high doses (100 mg and above). Gastrointestinal AEs were frequent at high doses.

Aims The aim was to characterize the population pharmacokinetics of BYL719 in cancer patients and assess the time course of tumour response in relation to drug exposure and dosing schedule. Methods Plasma samples and longitudinal tumour size measurements were collected from 60 patients with advanced solid malignancies who received oral BYL719 once daily (30–450 mg) or twice daily at 120 mg or 200 mg. Non-linear mixed effect modelling was employed to develop the population pharmacokinetic and pharmacodynamic model. Results The pharmacokinetics were best described by a one compartment disposition model and transit compartments accounting for the lag time in absorption. The typical population oral clearance and volume of distribution estimates with their between-subject variability (BSV) were 10 l h−1 (BSV 26%) and 108 l (BSV 28%), respectively. The estimated optimal number of transit compartments was 8.1, with a mean transit time to the absorption compartment of 1.28 h (BSV 32%). The between-occasion variability in the rate and extent of absorption was 46% and 26%, respectively. Tumour growth was modelled using a turnover model characterized by a zero order growth rate of 0.581 cm week1 and a first order death rate of 0.0123 week−1. BYL719 inhibited tumour growth with an IC50 of 100 ng ml−1 (BSV 154%). Model-based predictions showed potential for additional anti-tumour activity of twice daily dosing at total daily dose below 400 mg, but a loss of efficacy if administered less frequently than once daily. Conclusions The proposed model provides a valuable approach for planning future clinical studies and for designing optimized dosing regimens with BYL719.

Buparlisib (BKM120) is an oral pan-phosphatidylinositol 3-kinase inhibitor, targeting all four isoforms of class I PI3K (α, β, γ and δ). This open-label Phase I dose-escalation study was conducted to determine the maximum tolerated dose of continuous daily buparlisib in Japanese patients with advanced solid tumors. Secondary objectives included safety and tolerability, pharmacokinetics, antitumor activity and pharmacodynamic marker changes. Fifteen patients were treated at 25 mg/day (n = 3), 50 mg/day (n = 3) and 100 mg/day (n = 9) dose levels. One dose-limiting toxicity of Grade 4 abnormal liver function occurred at 100 mg/day. Considering the safety profile and the maximum tolerated dose in the first-in-man study of buparlisib in non-Japanese patients, further dose escalation was stopped and 100 mg/day was declared the recommended dose. The most common treatment-related adverse events were rash, abnormal hepatic function (including increased transaminase levels), increased blood insulin levels and increased eosinophil count. Hyperglycemia was experienced by two patients, one Grade 1 and one Grade 4, and mood alterations were experienced by three patients, two Grade 1 and one Grade 2. Pharmacokinetic results showed that buparlisib was rapidly absorbed in a dose-proportional manner. Best overall response was stable disease for six patients, including one unconfirmed partial response. In these Japanese patients with advanced solid tumors, buparlisib had a manageable safety profile, with similar pharmacokinetics to non-Japanese patients. The recommended dose of 100 mg/day will be used in future studies of buparlisib in Japanese patients.

Background: Phosphatidylinositol-3-kinase (PI3K) pathway activation has been associated with resistance to anti-estrogen receptor (ER) therapy and PIK3CA mutated ER+ breast cancer (BC) cells are sensitive to inhibition of PI3K under estrogen deprivation. In an in vitro study, the combination of BYL719 and fulvestrant was synergistic in PIK3CA mutated BC cell lines. In the BYL719 single agent part of this study out of 21 ER+ BC patients (pts), 3 partial responses were observed and 5 pts remained on the study with stable disease for over 26 weeks. Median PFS in pts with ER+ PIK3CA mutated BC was 5.5 months (Gonzalez-Angulo, 2013). Methods: This phase I study was amended to determine the Maximum Tolerated Dose (MTD) of BYL719 in combination with the ER antagonist fulvestrant in PIK3CA mutated ER+ breast cancer pts. Dose escalation of BYL719 in combination with fixed dose fulvestrant used an adaptive Bayesian logistic regression model with overdose control. The starting dose of BYL719 was 300 mg once daily, 25% below the MTD of single agent BYL719. All pts received the standard dose of 500 mg fulvestrant every 4 weeks. No dose escalation of fulvestrant was permitted. Following the MTD declaration, a dose expansion cohort will open. Results: At the data cut-off (27 March 2013), 4 pts were enrolled in the initial cohort of 300 mg/q.d. BYL719 plus 500 mg/qmonth (with an additional dose at week 2) fulvestrant, followed by 8 pts into the subsequent 400 mg/q.d. BYL719 plus fulvestrant dose combination. No pts experienced dose limiting toxicity (DLT) in the 300 mg cohort, and 1 pt experienced a DLT of CTCAE grade 3 diarrhea, vomiting, fatigue, anorexia and bloating in the 400 mg cohort. The MTD of BYL719 in combination with fulvestrant has been declared as 400 mg/q.d. The most frequent BYL719 related toxicities (>15% pts), regardless of grade and treatment group, are diarrhea (42%), hyperglycemia (33%), decreased appetite (25%), nausea (25%), and fatigue (17%). Systemic drug exposure of oral BYL719 when given in combination with fulvestrant was found to be similar to the single agent data. The patients were typically pre-treated with numerous chemotherapy, hormonal or targeted therapies. One pt in the 300 mg/q.d. cohort had a confirmed partial response, and 2 pts in the 400 mg/q.d. cohort had a partial response (one confirmed and one only occurring after the data cut-off). From the 12 breast cancer pts treated, 2 (17%) discontinued treatment due to progressive disease, and the median exposure of all pts at the time of data cut-off was 9 weeks. Conclusions: This combination displays a favorable safety and PK profile, both comparable to the single agent BYL719 experience. BYL719 in combination with fulvestrant shows encouraging preliminary anti-tumor activity, which supports further investigation of this combination. Recruitment within the dose expansion is continuing to obtain a sample size of 20 patients carrying the PIK3CA mutation. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P2-16-14.

HSP90 enables the activation of many client proteins of which the most clinically validated is HER2. NVP-AUY922, a potent HSP90 inhibitor, is currently in phase II clinical trials. To explore its potential clinical use in HER2-amplified breast and gastric cancers, we evaluated the effect of AUY922 alone and in combination with trastuzumab in both trastuzumab-sensitive and -resistant models. A panel of 16 human gastric and 45 breast cancer cell lines, including 16 HER2-amplified (3 and 13, respectively) cells, was treated with AUY922 over various concentrations. In both breast and gastric cancer, we used cell lines and xenograft models with conditioned trastuzumab-resistance to investigate the efficacy of AUY922 alongside trastuzumab. Effects of this combination on downstream markers were analyzed via Western blot analysis. AUY922 exhibited potent antiproliferative activity in the low nanomolar range (

Background: Deregulation of the PI3K pathway occurs in >50% of breast cancers. Mutations in PIK3CA, the gene encoding the p110alpha subunit of PI3K contributes to resistance to endocrine and anti-HER2 therapies. BYL719 is a potent, specific oral inhibitor of the alpha subunit of PI3K, which inhibits wild-type p110alpha and its most common somatic mutations (IC50=5 nM) much more potently than other PI3K isoforms. Methodology: BYL719 has been investigated in a phase I study in patients with PIK3CA mutant advanced solid tumors. BYL719 has a favorable safety and PK profile; the MTD was established at 400 mg once daily (Juric et al., AACR 2012). As of 5 September 2012, 79 patients have been enrolled in this phase I study, among them 20 patients with PIK3CA mutant ER+ MBC. 5 of these patients had ER+/HER2 positive (HER2+) MBC. Presence of PIK3CA mutations was determined by either local or central assessment. Results: 20 patients with ER+ PIK3CA mutant MBC were treated once daily with BYL719 at doses of 30 mg (n = 1), 180 mg (n = 1), 270 mg (n = 1), 400 mg (n = 14) and 450 mg (n = 3). Median age was 55 years (range 40–78). 15/20 patients with ER+ PIK3CA mutant MBC had HER2 negative and 5/20 had HER2+ MBC. Patients had received a median of 5 previous treatment regimens (range 1–11). Most patients had received multiple prior lines of endocrine therapy including tamoxifen and aromatase inhibitors; 9 patients also received fulvestrant and 16 patients received prior chemotherapy. HER2+ patients have been previously treated with trastuzumab and/or lapatinib. Based on a recent analysis of 19 patients (data cut-off 5 July 2012), the safety of BYL719 in patients with ER+ MBC was comparable to the overall study population. Most frequent adverse events (AEs; ≥10%) suspected to be related to BYL719 were hyperglycemia, diarrhea, nausea, fatigue, decreased appetite, vomiting, rash and erythematous rash, dysgeusia, dry mouth, and stomatitis. The majority of AEs were CTCAE grade 1/2 and were clinically well manageable. Most frequent CTCAE grade 3/4 events were hyperglycemia and erythematous rash. 18/20 PIK3CA mutant ER+ MBC patients were treated at potentially effective doses of ≥270 mg/day. 6/18 patients (33%) achieved tumor shrinkage > 20%, among them 2 patients achieved partial responses (PR) by RECIST. Median progression free survival (PFS) analyzed in 17 patients treated at ≥270 mg/day in the ER+ BC patients was 7.3 months (CI [4.6,9.5]), compared to 3.7 months (CI [1.8,5.5]) in 38 patients with other PIK3CA mutant solid tumors (data cut-off 5 July 2012) Conclusion: BYL719 has a favorable safety profile with manageable side effects, which were mainly related to its mechanism of action. BYL719 shows promising preliminary clinical activity as single agent in patients with PIK3CA mutant ER+ MBC, warranting further clinical development. The investigation of BYL719 continues in patients with ER+ MBC as single agent, and in combination with endocrine therapy. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P6-10-07.

Background Phosphatidylinositol 3-kinase (PI3K) is critical to cancer cell growth, survival, and metabolism. BKM120 is an oral pan-class I (α, β, γ, δ) PI3K inhibitor that has demonstrated in vitro and in vivo tumor cell growth inhibition in a range of cancer types including breast cancer. Materials and methods: The Phase I study CBKM120X2101 investigating single-agent daily BKM120 in patients (pts) with advanced solid tumors has been recently completed with the maximum tolerated dose established at 100 mg/day. Here, we report the analysis of metastatic breast carcinoma (MBC) pts enrolled in this study. Results: Overall, 83 pts have enrolled, 21 of whom have MBC. At the cut-off date of 25th February 2011, 20 MBC pts were evaluable: 1 pt at 80 mg, 1 pt at 150 mg and 18 pts at 100 mg. Patient characteristics were as follows: median age 55 years (range 37–71); performance status ECOG 0/1/2 for 7/12/1 pts, respectively; visceral disease was reported in 16 pts, including liver, 10 pts (50%); lung, 9 pts (45%); and pleura, 5 pts (25%); all pts had >3 lines of systemic therapy (3-12). The median time from last treatment and study entry was 46 days (29-235). The median duration of BKM120 treatment administered was 7.5 weeks (1.0−96.4). The most frequent grade 3 drug-related adverse events (AEs) were: transaminases increase, 4 pts; psychiatric disorders, 3 pts, consisting of anxiety, affective disorder, and mood alteration (1 pt each); diarrhea, 2 pts; fatigue, 2 pts; and hyperglycemia, 1 pt. The only grade 4 drug-related AE was hyperglycemia, reported in 1 pt at 150 mg. Most AEs were manageable with treatment interruption and dose reductions. Eighteen pts were evaluable for objective tumor response by RECIST. Two pts (11%) exhibited partial responses, which were confirmed in a triple-negative MBC pt, and unconfirmed in an ER+ HER2− MBC pt. For these 2 pts, the treatment duration was 29+ (ongoing) and 6 months, respectively. An additional 9 pts (50%) had stable disease, lasting >4 months in 7 pts (35%). Conclusions: This preliminary analysis showed that BKM120 has single-agent activity in heavily pretreated pts with MBC, and an acceptable safety profile. Molecular profiling and updated pharmacokinetic results will be presented at the meeting. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P3-16-01.

Angiogenesis is a critical step in tumor development, in which vascular endothelial growth factor (VEGF) is a key growth aspect. Heat shock protein 90 (HSP90), a molecular chaperone, is essential for the activity of key proteins involved in VEGF transcription. Currently, no biomarkers to predict the effect of, or monitor, HSP90 inhibition therapy in individual patients exist. (89)Zr-bevacizumab PET provides a noninvasive tool to monitor tumor VEGF levels. The aim of this study was to investigate (89)Zr-bevacizumab PET for early antiangiogenic tumor response evaluation of treatment with the new HSP90 inhibitor NVP-AUY922. In xenografts of A2780 and its cisplatin-resistant CP70 human ovarian cancer subline, (89)Zr-bevacizumab small-animal PET was performed before and after NVP-AUY922 treatment and verified with histologic response and ex vivo tumor VEGF levels. Compared with pretreatment values, 2 wk of NVP-AUY922 treatment decreased (89)Zr-bevacizumab uptake by 44.4% (P = 0.0003) in A2780 xenografts, whereas tumor uptake was not affected in CP70 xenografts. The same pattern was observed in A2780 and CP70 tumor VEGF levels, measured with enzyme-linked immunosorbent assay, and mean vessel density after NVP-AUY922 treatment. These findings coincided with reduction in the proliferation rate, assessed by Ki67 staining, in A2780 tumor tissue only. CONCLUSION: (89)Zr-bevacizumab PET was in line with the antiangiogenic response and direct antitumor effects after NVP-AUY922 treatment, supporting the specificity of (89)Zr-bevacizumab PET as a sensitive technique to monitor the antiangiogenic response of HSP90 inhibition in vivo.

The 90 kD heat shock protein (Hsp90) molecular chaperone sustains multiple components of oncogenic pathways and has recently emerged as a therapeutic target that is now being clinically tested in a number of malignancies. In order to address formulation issues and to deal with possible resistance mechanisms against small molecule Hsp90 inhibitors, a range of compounds based on different molecular scaffolds are now being developed. The present study preclinically tested the effects of the novel 2-aminothienopyrimidine class Hsp90 inhibitor NVP-BEP800, which is suitable for oral formulations, on multiple myeloma cells from established cell lines and on a larger cohort (n = 40) of primary myeloma samples. The drug effectively and specifically killed the majority of primary myeloma cells in coculture with bone marrow stromal cells and reliably entailed molecular consequences of Hsp90 blockade - such as survival pathway breakdown and client protein depletion - in multiple myeloma cells from cell lines as well as from patients. Collectively, the properties of this novel drug support clinical testing in multiple myeloma.

We as well as others have recently shown that Hsp90 is overexpressed in multiple myeloma (MM) and critically contributes to tumour cell survival. Pharmacologic blockade of Hsp90 has consistently been found to induce MM cell death. However, most data have been obtained with MM cell lines whereas knowledge about the molecular effects of pharmacologic Hsp90 blockade in primary tumour cells is limited. Furthermore, these investigations have so far focused on geldanamycin derivatives. We analysed the biochemical effects of a novel diarylisoxazole-based Hsp90 inhibitor (NVP-AUY922) on signalling pathways and cell death in a large set of primary MM tumour samples and in MM cell lines. Treated cells displayed the molecular signature and pharmacodynamic properties for abrogation of Hsp90 function, such as downregulation of multiple survival pathways and strong upregulation of Hsp70. NVP-AUY922 treatment efficiently induced MM cell apoptosis and revealed both sensitive and resistant subgroups. Sensitivity was not correlated with TP53 mutation or Hsp70 induction levels and stromal cells from the bone marrow microenvironment were unable to abrogate NVP-AUY922-induced apoptosis of MM cells. Thus, NVP-AUY922 may be a promising drug for treatment of MM and clinical studies are warranted.

Activating mutations of the PIK3CA gene occur frequently in breast cancer, and inhibitors that are specific for phosphatidylinositol 3-kinase (PI3K) p110α, such as BYL719, are being investigated in clinical trials. In a search for correlates of sensitivity to p110α inhibition among PIK3CA-mutant breast cancer cell lines, we observed that sensitivity to BYL719 (as assessed by cell proliferation) was associated with full inhibition of signaling through the TORC1 pathway. Conversely, cancer cells that were resistant to BYL719 had persistently active mTORC1 signaling, although Akt phosphorylation was inhibited. Similarly, in patients, pS6 (residues 240/4) expression (a marker of mTORC1 signaling) was associated with tumor response to BYL719, and mTORC1 was found to be reactivated in tumors from patients whose disease progressed after treatment. In PIK3CA-mutant cancer cell lines with persistent mTORC1 signaling despite PI3K p110α blockade (that is, resistance), the addition of the allosteric mTORC1 inhibitor RAD001 to the cells along with BYL719 resulted in reversal of resistance in vitro and in vivo. Finally, we found that growth factors such as insulin-like growth factor 1 and neuregulin 1 can activate mammalian target of rapamycin (mTOR) and mediate resistance to BYL719. Our findings suggest that simultaneous administration of mTORC1 inhibitors may enhance the clinical activity of p110α-targeted drugs and delay the appearance of resistance.

Purpose: A phase I study was conducted with the primary objective of determining the maximum tolerated dose (MTD) of AUY922 in patients with advanced solid tumors. Secondary objectives included characterization of the safety, pharmacokinetic, and pharmacodynamic profiles. Patients and Methods: Patients with advanced solid tumors received 1-hour i.v. infusions of AUY922 once a week in a 28-day cycle. An adaptive Bayesian logistic regression model that employed observed dose-limiting toxicities (DLT) in the first treatment cycle was used to guide dose-escalation decisions, with the established MTD to be used in phase II studies. Results: One hundred and one patients were enrolled and explored at doses in the range of 2 to 70 mg/m2. DLTs occurred in 8 patients (22–70 mg/m2) and included diarrhea, asthenia/fatigue, anorexia, atrial flutter, and visual symptoms. At 70 mg/m2, the AUY922 concentration achieved was consistent with active concentrations in a range of xenograft models. There was evidence of target inhibition in peripheral blood mononuclear cells (HSP70 induction) and tumor (client protein depletion and reduction of metabolic activity by 18F-FDG PET). The recommended phase II dose (RP2D) of 70 mg/m2 was proposed on the basis of toxicity and pharmacokinetic and pharmacodynamic profiles. Conclusions: At the RP2D of 70 mg/m2, AUY922 exhibited acceptable tolerability, and phase II single-agent and combination studies have been initiated in patients with HER2-positive breast, gastric, and non–small cell lung cancers. Clin Cancer Res; 19(13); 3671–80. ©2013 AACR.

Heat shock protein 90 (HSP90) is involved in protein folding and functions as a chaperone for numerous client proteins, many of which are important in non–small cell lung cancer (NSCLC) pathogenesis. We sought to define preclinical effects of the HSP90 inhibitor NVP-AUY922 and identify predictors of response. We assessed in vitro effects of NVP-AUY922 on proliferation and protein expression in NSCLC cell lines. We evaluated gene expression changes induced by NVP-AUY922 exposure. Xenograft models were evaluated for tumor control and biological effects. NVP-AUY922 potently inhibited in vitro growth in all 41 NSCLC cell lines evaluated with IC50 < 100 nmol/L. IC100 (complete inhibition of proliferation) < 40 nmol/L was seen in 36 of 41 lines. Consistent gene expression changes after NVP-AUY922 exposure involved a wide range of cellular functions, including consistently decreased dihydrofolate reductase after exposure. NVP-AUY922 slowed growth of A549 (KRAS-mutant) xenografts and achieved tumor stability and decreased EGF receptor (EGFR) protein expression in H1975 xenografts, a model harboring a sensitizing and a resistance mutation for EGFR-tyrosine kinase inhibitors in the EGFR gene. These data will help inform the evaluation of correlative data from a recently completed phase II NSCLC trial and a planned phase IB trial of NVP-AUY922 in combination with pemetrexed in NSCLCs. Mol Cancer Ther; 12(6); 890–900. ©2013 AACR.

2531 Background: BYL719 is an oral small-molecule inhibitor of the p110α catalytic subunit of phosphatidylinositol 3-kinase (PI3K), which is encoded by the PIK3CA gene, one of the most commonly mutated genes in human cancers. BYL719 inhibits proliferation of PI3Kα-driven cancer cell lines in vitro and causes regression of PIK3CA-mutant tumor models in vivo. Methods: This Ph I study was performed in patients (pts) with advanced solid tumors carrying a somatic mutation of PIK3CA. Dose escalation used an adaptive Bayesian logistic regression model with overdose control. Following determination of the maximum tolerated dose (MTD), an expansion cohort was opened at the MTD to evaluate safety, pharmacokinetics (PK), and clinical activity in pts with PIK3CA-mutant advanced solid tumors, including estrogen receptor-positive (ER+) metastatic breast cancer (mBC). Results: During dose escalation 36 pts received doses up to 450 mg/d, where 4/9 pts had dose-limiting toxicities (DLTs). The MTD for once-daily dosing was declared as 400 mg/d. As of Nov 20 2012, DLTs were hyperglycemia, nausea, vomiting, and diarrhea. The most common BYL719-related adverse events (all grades, all cohorts, >25%) were hyperglycemia (49%), nausea (45%), diarrhea (40%), decreased appetite (38%), vomiting (30%), and fatigue (27%). 39 pts are enrolled in the MTD dose-expansion cohort. Investigation of a twice-daily regimen is also ongoing. BYL719 has a favorable, approximately dose-proportional PK profile with a Tmax of 2h and a T½ of 11h at the MTD. Partial responses were seen in 7 pts (in ER+ breast [2], cervical, trichilemmal, endometrial, ovarian, and head &neck cancer [1 each]); 17 pts stayed on study for >24 weeks. For 67 pts (76%) treated at doses of ≥270 mg/d, the median progression-free survival (mPFS) was 3.6 months (mo; 95% CI: 3.5–5.5 mo). mPFS in 15 ER+ HER2– mBC pts treated at ≥270 mg/d was 5.5 mo (95% CI: 3–7 mo). Conclusions: BYL719 displays dose-proportional and predictable PK. The safety profile is favorable, with mostly manageable on-target toxicities. At doses of ≥270 mg/d, tumor regression and prolonged disease control were observed in heavily pretreated pts with various tumor types carrying a PIK3CA mutation. Clinical trial information: NCT01219699.

NVP-AUY922, a potent heat shock protein (HSP) 90 inhibitor, downregulates the expression of many oncogenic proteins, including the human epidermal growth factor receptor-2 (HER2). Because HER2 downregulation is a potential biomarker for early response to HSP90-targeted therapies, we used the Zr-89-labelled HER2 antibody trastuzumab to quantify the alterations in HER2 expression after NVP-AUY922 treatment with HER2 positron emission tomography (PET) imaging.The HER2 overexpressing human SKOV-3 ovarian tumour cell line was used for in vitro experiments and as xenograft model in nude athymic mice. In vitro HER2 membrane expression was assessed by flow cytometry and a radio-immuno assay with Zr-89-trastuzumab. For in vivo evaluation, mice received 50 mg/kg NVP-AUY922 intraperitoneally every other day. Zr-89-trastuzumab was injected intravenously 6 d before NVP-AUY922 treatment and after 3 NVP-AUY922 doses. MicroPET imaging was performed at 24, 72 and 144 h post tracer injection followed by ex-vivo biodistribution and immunohistochemical staining.After 24 h NVP-AUY922 treatment HER2 membrane expression showed profound reduction with flow cytometry (80%) and radio-immuno assay (75%). PET tumour quantification, showed a mean reduction of 41% (p = 0.0001) in Zr-89-trastuzumab uptake at 144 h post tracer injection after NVP-AUY922 treatment. PET results were confirmed by ex-vivo Zr-89-trastuzumab biodistribution and HER2 immunohistochemical staining.NVP-AUY922 effectively downregulates HER2, which can be monitored and quantified in vivo non-invasively with Zr-89-trastuzumab PET. This technique is currently under clinical evaluation and might serve as an early biomarker for HSP90 inhibition in HER2 positive metastatic breast cancer patients. (C) 2009 Elsevier Ltd. All rights reserved.

Heat shock protein 90 (HSP90) is a promising target for tumor therapy. The novel HSP90 inhibitor NVP-AUY922 has preclinical activity in multiple myeloma, however, little is known about effective combination partners to design clinical studies. Multiple myeloma cell lines, OPM-2, RPMI-8226, U-266, LP-1, MM1.S, and primary myeloma cells were exposed to NVP-AUY922 and one of the combination partners histone deacetylase inhibitor NVP-LBH589, suberoylanilide hydroxamic acid (SAHA), melphalan, or doxorubicin, either simultaneously or in sequential patterns. Effects on cell proliferation and apoptosis were determined. Synergistic effects were evaluated using the method of Chou and Talalay. Combined sequential incubation with NVP-AUY922 and SAHA showed that best synergistic effects were achieved with 24 h preincubation with SAHA followed by another 48 h of combination treatment. Combination of NVP-AUY922 with SAHA, NVP-LBH589, melphalan, or doxorubicin resulted in synergistic inhibition of viability, with strong synergy (combination index < 0.3) in the case of melphalan. Importantly, resistance of the RPMI-8226 cell line and relative resistance of some primary myeloma cells against NVP-AUY922 could be overcome by combination treatment. These data show impressive synergistic action of the novel HSP90 inhibitor NVP-AUY922 with melphalan, doxorubicin, NVP-LBH589, and SAHA in multiple myeloma and build the frame work for clinical trials.

Introduction Heat shock protein 90 (HSP90) is a key component of a multichaperone complex involved in the post-translational folding of a large number of client proteins, many of which play essential roles in tumorigenesis. HSP90 has emerged in recent years as a promising new target for anticancer therapies. Methods The concentrations of the HSP90 inhibitor NVP-AUY922 required to reduce cell numbers by 50% (GI50 values) were established in a panel of breast cancer cell lines and patient-derived human breast tumors. To investigate the properties of the compound in vivo, the pharmacokinetic profile, antitumor effect, and dose regimen were established in a BT-474 breast cancer xenograft model. The effect on HSP90-p23 complexes, client protein degradation, and heat shock response was investigated in cell culture and breast cancer xenografts by immunohistochemistry, Western blot analysis, and immunoprecipitation. Results We show that the novel small molecule HSP90 inhibitor NVP-AUY922 potently inhibits the proliferation of human breast cancer cell lines with GI50 values in the range of 3 to 126 nM. NVP-AUY922 induced proliferative inhibition concurrent with HSP70 upregulation and client protein depletion – hallmarks of HSP90 inhibition. Intravenous acute administration of NVP-AUY922 to athymic mice (30 mg/kg) bearing subcutaneous BT-474 breast tumors resulted in drug levels in excess of 1,000 times the cellular GI50 value for about 2 days. Significant growth inhibition and good tolerability were observed when the compound was administered once per week. Therapeutic effects were concordant with changes in pharmacodynamic markers, including HSP90-p23 dissociation, decreases in ERBB2 and P-AKT, and increased HSP70 protein levels. Conclusion NVP-AUY922 is a potent small molecule HSP90 inhibitor showing significant activity against breast cancer cells in cellular and in vivo settings. On the basis of its mechanism of action, preclinical activity profile, tolerability, and pharmaceutical properties, the compound recently has entered clinical phase I breast cancer trials.

The PI3K-AKT-mTOR pathway is frequently activated in cancer. PI3K inhibitors, including the pan-PI3K inhibitor buparlisib (BKM120) and the PI3Kα-selective inhibitor alpelisib (BYL719), currently in clinical development by Novartis Oncology, may therefore be effective as anticancer agents. Early clinical studies with PI3K inhibitors have demonstrated preliminary antitumor activity and acceptable safety profiles. However, a number of unanswered questions regarding PI3K inhibition in cancer remain, including: what is the best approach for different tumor types, and which biomarkers will accurately identify the patient populations most likely to benefit from specific PI3K inhibitors? This review summarizes the strategies being employed by Novartis Oncology to help maximize the benefits of clinical studies with buparlisib and alpelisib, including stratification according to PI3K pathway activation status, selective enrollment/target enrichment (where patients with PI3K pathway-activated tumors are specifically recruited), nonselective enrollment with mandatory tissue collection, and enrollment of patients who have progressed on previous targeted agents, such as mTOR inhibitors or endocrine therapy. An overview of Novartis-sponsored and Novartis-supported trials that are utilizing these approaches in a range of cancer types, including breast cancer, head and neck squamous cell carcinoma, non-small cell lung carcinoma, lymphoma, and glioblastoma multiforme, is also described.

Background: BYL719 selectively inhibits the α-isoform of Class I PI3K. PI3Kα is encoded by PIK3CA, a frequently altered gene in human cancers. Preclinical data indicate BYL719 may be more effective in patients (pts) with PIK3CA-altered tumors; however there are data to suggest that PIK3CA-wild-type (wt) tumors may also be sensitive to BYL719. Here, we present updated data from the Phase I study of BYL719 + fulvestrant in pts with PIK3CA-altered or -wt ER+/HER2– locally advanced/metastatic breast cancer (BC) (NCT01219699). Methods: Adult women with PIK3CA-altered (mutation or amplification) ER+/HER2– BC received continuous oral BYL719 (300–400 mg/day; 28-day cycles) + fixed-dose fulvestrant (500 mg every 4 weeks, plus an additional dose 2 weeks after first dose) during dose escalation and expansion. Pts with PIK3CA-wt ER+/HER2– BC were enrolled into the dose expansion to receive BYL719 400 mg/day + fulvestrant. A Bayesian logistic regression model with overdose control guided dose escalation. Primary objective: to determine the maximum tolerated dose (MTD) and/or recommended phase II dose (RP2D) of BYL719 in combination with fulvestrant, which was declared previously as 400 mg/day. An expansion cohort at the MTD assessed safety (CTCAE v4.0), tolerability, pharmacokinetics (PK), and preliminary efficacy (RECIST v1.0). Results: As of May 2, 2014, 64 pts (PIK3CA-altered n=41; PIK3CA-wt n=16; PIK3CA status unknown/pending n=7) received BYL719 300–400 mg/day + fulvestrant. Median number of prior antineoplastic therapies: 5 (range: 1–12) for pts with PIK3CA-altered tumors and 5 (range: 4–16) for pts with PIK3CA-wt tumors. Prior fulvestrant treatment: 19 (46%) and 7 (44%) pts with PIK3CA-altered and -wt tumors, respectively. Overall, the most common (≥25%) adverse events (AEs; all grades/all doses) suspected to be study drug-related were hyperglycemia (41%), diarrhea (34%), nausea (30%), and vomiting (25%). The most common (>10%) study drug-related Grade 3/4 AEs (all doses) were maculopapular rash (14%) and hyperglycemia (13%). Preliminary antitumor activity was observed in this trial. At data cut-off, partial responses (PRs) were observed in 2 patients with PIK3CA-altered tumors evaluable for response (2/33, 6%), but no PRs were observed in the 15 evaluable patients with PIK3CA-wt tumors. Duration of exposure was >16 weeks in 24 (59%) patients with PIK3CA-altered tumors and in 5 (31%) patients with PIK3CA-wt tumors. PK and exposure of BYL719 + fulvestrant was similar to that observed with single-agent BYL719 at the same dose levels. At data cut-off, treatment was ongoing in 20 (49%) and 2 (13%) pts with PIK3CA-altered and -wt tumors, respectively. Conclusions: BYL719 + fulvestrant demonstrated a favorable safety profile in pts with PIK3CA-altered and -wt ER+/HER2– BC, with mostly on-target effects (i.e. hyperglycemia, rash). Preliminary clinical activity was seen in pts with PIK3CA-altered and -wt tumors, but confirmed PRs were only observed in pts with PIK3CA-altered tumors. The low number of pts with PIK3CA-wt tumors limits further conclusion. Citation Format: Filip Janku, Dejan Juric, Javier Cortes, Hope Rugo, Howard A Burris, Martin Schuler, Barbara Deschler-Baier, Mark R Middleton, Marta Gil-Martin, Jordan Berlin, Eric Winer, Douglas Bootle, Lars Blumenstein, David Demanse, Christina Coughlin, Cornelia Quadt, José Baselga. Phase I study of the PI3Kα inhibitor BYL719 plus fulvestrant in patients with PIK3CA-altered and wild type ER+/HER2- locally advanced or metastatic breast cancer [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr PD5-5.

Aim of the study Adecatumumab (also known as MT201) is a human recombinant IgG1 monoclonal antibody binding with low affinity to epithelial cell adhesion molecule (EpCAM). To explore safety, pharmacokinetics and pharmacodynamics of adecatumumab, a phase I trial in patients with hormone refractory prostate cancer (HRPC) was performed. Methods Twenty patients were treated with two adecatumumab infusions on days 0 and 14 in cohorts with doses of ten up to 262 mg/m 2 . Results Adecatumumab was well tolerated at all doses tested, and no maximum tolerated dose reached. Most adverse events were mild or moderate with pyrexia and nausea being most frequent. The highest dose of adecatumumab induced shortly after infusion robust and transient increases of TNF-alpha serum levels. At all doses, significant transient declines of peripheral natural killer cells were observed shortly after antibody infusions. Adecatumumab had a serum half-life of 15 days, and immune responses to the antibody were not detected. Conclusions A benign safety profile, long serum half-life and low immunogenicity do warrant further exploration of adecatumumab for treatment of EpCAM-expressing neoplasia.

BscCD19xCD3 is a bispecific single-chain antibody construct with exceptional cytotoxic potency in vitro and in vivo. Here, we have investigated the biological activity of bscCD19xCD3 in chimpanzee, the only animal species identified in which bscCD19xCD3 showed bispecific binding, redirected B-cell lysis and cytokine production comparable to human cells. Pharmacokinetic analysis following 2-h intravenous infusion of 0.06, 0.1 or 0.12 mug/kg of bscCD19xCD3 as part of a dose escalation study in a single female chimpanzee revealed a half-life of approximately 2 h and elimination of the bispecific antibody from circulation within approximately 8 h after the end of infusion. This short exposure to bscCD19xCD3 elicited a transient increase in serum levels of IFNgamma, IL-6, IL-2, soluble CD25, and transiently upregulated expression of CD69 and MHC class II on CD8-positive cells. Cytokine release and upregulation of T-cell activation markers were not observed with vehicle controls. A multiple-dose study using 5 weekly doses of 0.1 mug/kg in two animals also showed transient cytokine release and an activation of peripheral T cells with a first-dose effect, accompanied by a transient lymphopenia. While oscillations of T-cell counts were relatively even during repeated treatments, the amplitudes of peripheral B cells declined with every infusion, which was not observed in a vehicle control animal. Our data show that bscCD19xCD3 can be safely administered to chimpanzees at dose levels that cause fully reversible T-cell activation and, despite a very short exposure time, cumulative loss of peripheral B lymphocytes. A clinical trial testing prolonged administration of bscCD19xCD3 (MT103) for improving efficacy is currently ongoing.

Activating mutations of PIK3CA, the gene encoding the p110α subunit of PI3K, are frequent in breast cancer and selective inhibitors of this enzyme have shown promising clinical activity in breast tumors harboring these mutations. We studied the case of a patient with metastatic breast cancer harboring a PIK3CA mutation that was treated in a clinical trial with BYL719, a highly selective PI3Kα inhibitor. The treatment resulted in a robust partial response that lasted 7 months followed by rapid progression and death. A rapid autopsy was performed with collection of tissue samples from 16 different metastatic sites. We compared by whole genome and exome sequencing the original primary tumor, a rapidly progressing lung metastasis and a periaortic lesion that was still responding to BYL719 at time of death. Besides several common alterations, PTEN loss and a missense mutation were detected only in the lung metastasis. Using targeted exome sequencing we analyzed all the other available samples. Strikingly, we observed a consistent loss in PTEN (via different mechanisms such as deletion, splice site mutation and frameshift mutations) in all the lesions refractory to BYL719 but not in the responding ones. In every case, the loss of PTEN was also documented by lack of protein expression by immunohistochemistry (IHC). Finally, we were able to build a dendrogram showing the phylogenetic evolution of the lesions and the evolutionary convergence of the PTEN alterations. To validate PTEN loss as a possible mechanism of acquired resistance to selective PI3Kα inhibition, we generated doxycycline-inducible PTEN shRNA stable clones starting from three different BYL719-sensitive cell lines. In all the studied models, induction of PTEN shRNA resulted in resistance to BYL719. Since PTEN deficient genetic models have been shown to rely on the β subunit of the PI3K holoenzyme, we tested whether the concomitant inhibition of both p110α and p110β was sufficient to revert the resistant phenotype. BKM120 (a pan-PI3K inhibitor) or the addition of AZD6482 (p110β inhibitor) to BYL719 re-sensitized the cells to BYL719. To expand our findings in vivo, we generated a patient-derived xenograft (PDX) model from a PTEN-null non-responding lesion (lung). Consistently, this PDX model was refractory to the antitumor activity of BYL719 but conserved sensitivity to BKM120 or the combination of AZD6482 and BYL719. In both cases, IHC analysis revealed a decrease in PI3K/AKT downstream effectors pPRAS40 (246) and pS6 (240/4) staining with BKM120 or AZD6482+BYL719, but not with BYL719 alone. Preliminary analyses of other samples collected from patients treated with BYL719 suggest that PTEN loss is a relatively frequent event upon therapy progression. Taken together, the different mechanisms that inactivate PTEN in the tumor treated with BYL719 can be explained by convergent phenotypic evolution in a heterogeneous tumor and highlight the importance of PTEN and PI3Kβ in acquired resistance to PI3Kα inhibitors. Citation Format: Pau Castel, Dejan Juric, Helen Won, Benjamin Ainscough, Haley Ellis, Saya Ebbesen, Malachi Griffith, Obi Griffith, Iyer Gopakumar, Dennis Sgroi, Steven Isakoff, Elaine Mardis, David Solit, Scott Lowe, Cornelia Quadt, Malte Peters, Michael Berger, Maurizio Scaltriti, José Baselga. Loss of PTEN leads to clinical resistance to the PI3Kα inhibitor BYL719 and provides evidence of convergent evolution under selective therapeutic pressure. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr LB-327. doi:10.1158/1538-7445.AM2014-LB-327

Activating mutations of the PIK3CA gene occur frequently in breast cancer and inhibitors that are specific for PI3K p110α, such as BYL719, are being investigated in clinical trials. In a search for correlates of sensitivity to p110α inhibition among PIK3CA-mutant breast cancer cell lines, we observed that sensitivity to BYL719 (as assessed by cell proliferation) was associated with full inhibition of signaling through the TORC1 pathway. Conversely, cancer cells that were resistant to BYL719 had persistently active mTORC1 signaling, although Akt phosphorylation was inhibited. Similarly in patients, pS6 (residues 240/4) expression (a marker of mTORC1 signaling) was associated with tumor response to BYL719, and mTORC1 was found to be reactivated in tumors from patients whose disease progressed after treatment. In PIK3CA-mutant cancer cell lines with persistent mTORC1 signaling despite PI3K p110α blockade (that is, resistance), the addition of the allosteric mTORC1 inhibitor RAD001 to the cells along with BYL719 resulted in reversal of resistance in vitro and in vivo. Finally, we found that growth factors such as IGF1 and neuregulin1 can activate mTOR and mediate resistance to BYL719. Our findings suggest that simultaneous administration of mTORC1 inhibitors may enhance the clinical activity of p110α targeted drugs and delay the appearance of resistance. Citation Information: Mol Cancer Ther 2013;12(11 Suppl):B106. Citation Format: Moshe Elkabets, Sadhna Vora, Dejan Juric, Natasha Morse, Mari Mino-Kenudson, Taru Muranen, Jessica Tao, Ana Bosch Campos, Jordi Rodon, Yasir H. Ibrahim, Violeta Serra, Vanessa Rodrik-Outmezguine, Saswati Hazra, Sharat Singh, Phillip Kim, Cornelia Quadt, Liu Manway, Alan Huang, Neal Rosen, Jeffrey A. Engelman, Maurizio Scaltriti, José Baselga. mTORC1 inhibition is required for sensitivity to PI3K p110α inhibitors in PIK3CA-mutant breast cancer. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr B106.

Background: BEZ235 is an oral, ATP-competitive inhibitor that targets class l PI3K and downstream effectors mTORC1/2. In previous phase I studies in mainly Western patients, the maximum tolerated dose (MTD) of single-agent BEZ235 solid dispersion system (SDS) sachet once daily (QD) was declared as 1200 mg and the recommended dose (RD) as 1000 mg; the MTD of the same formulation of BEZ235 twice daily (BID) was declared as 400 mg (Rodon EORTC-NCI-AACR 2012, Arkenau ASCO 2012). Here we present the results of a phase I, multicenter, open-label, dose escalation study of single-agent BEZ235 SDS sachet, administered QD or BID, in adult Japanese patients with advanced solid tumors (NCT01195376). Methods: Patients with histologically confirmed, unresectable advanced solid tumors not amenable to standard therapy, received continuous oral BEZ235, QD or BID in 28-day cycles. The primary objective was to determine the MTD/RD of single-agent BEZ235 in adult Japanese patients, based on dose-limiting toxicity (DLT) using a standard 3+3 method for dose escalation. MTD was defined as the highest dose causing DLT in no more than 1/6 patients in Cycle 1. Secondary objectives included preliminary antitumor activity (RECIST v1), safety profiles (CTCAE v3), and pharmacokinetics (PK). Results: As of Feb 10, 2013, 32 patients (mean age 58 yrs) were treated with BEZ235 at 2 dosing schedules; 27 patients received BEZ235 QD at 5 dose levels: 400, 800, 1000, 1200, or 1400 mg; and 5 patients received BEZ235 BID at 400 mg. 2 DLTs were reported with QD dosing: Grade 2 allergic reaction (1200 mg) and Grade 4 thrombocytopenia (1400 mg). Although equivalent DLT ratios were recorded at 1200 mg and 1400 mg (1/6 evaluable patients each), clinical observation led to 1200 mg being declared as the maximum, clinically tolerable dose and 1000 mg being declared as the RD of single-agent BEZ235 QD. The primary reason for discontinuation was disease progression (63%). Common suspected BEZ235-related AEs (≥40%) were diarrhea, decreased appetite, nausea, stomatitis, fatigue, vomiting, and rash; no difference in AE profile was observed between QD and BID schedules. Three patients experienced serious suspected BEZ235-related AEs: infectious enterocolitis, pneumonia, and diarrhea. No death related to treatment was reported. Best overall response was stable disease in 15/27 evaluable patients (56% disease control rate). After Feb 10, 2013, 3 additional patients were enrolled at 400 mg BID (8 in total) and 1 DLT (Grade 2 liver dysfunction) out of 6 evaluable patients was observed. PK data revealed a slow rate of absorption, less than dose-proportional exposure, and large interpatient variability for single-agent BEZ235 SDS sachet. Conclusions: The maximum, clinically tolerable dose of BEZ235 QD was declared as 1200 mg and the RD was declared as 1000 mg, in agreement with previous studies in Western populations. In addition, the tolerability of 400 mg BEZ235 BID was confirmed. The findings of this first-in-Japanese study suggest no major difference in BEZ235 tolerability and PK profile between Japanese and Western populations. Citation Information: Mol Cancer Ther 2013;12(11 Suppl):A167. Citation Format: Koichiro Watanabe, Hironobu Minami, Satoshi Otsu, Yoshinori Hirashima, Ryotaro Morinaga, Kazuo Nishikawa, Yasushi Hisamatsu, Toru Mukohara, Naomi Kiyota, Naoko Chayahara, Masanori Toyoda, Yoshinori Imamura, Yutaka Fujiwara, Cornelia Quadt, Matthew Robson, Kazuto Natsume, Takuji Aoki, Kuniaki Shirao. A phase I study of single-agent BEZ235 (SDS sachet), once- or twice-daily, in Japanese patients with advanced solid tumors. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr A167.

Background: BYL719 is an oral inhibitor that selectively targets the α-isoform of class l PI3K, which is encoded by PIK3CA, a frequently altered gene in human cancers. In a first-in-man Phase I study in mostly Western patients (including one Asian patient) with advanced solid malignancies harboring a PIK3CA alteration (mutation and/or amplification), the maximum tolerated dose (MTD) for once-daily (QD) BYL719 was declared as 400 mg, and preliminary antitumor activity was observed (Gonzalez-Angulo et al. ASCO 2013). Here, we report preliminary findings of an ongoing multicenter, open-label Phase l dose-escalation study in Japanese patients with advanced solid malignancies irrespective of PIK3CA alterations (NCT01387321). Methods: Patients were aged ≥18 years with histologically confirmed, advanced unresectable solid tumors, who had progressed despite standard therapy or for whom no standard therapy existed. Patients received continuous oral BYL719 QD in 28-day cycles until disease progression, unacceptable toxicity, or investigator/patient decision. Dose escalation was guided by an adaptive Bayesian logistic regression model with overdose control. The primary objective was to determine the MTD and/or recommended phase 2 dose (RP2D) of BYL719 QD. MTD was defined as the highest drug dosage not causing medically unacceptable does limiting toxicities (DLTs) in >33% of treated patients during Cycle 1. Secondary objectives included assessments of preliminary antitumor activity (RECIST v1.1), safety (CTCAE v4), and PK profiles. Results: As of May 20, 2013, 24 patients (median age 56 years) were enrolled, receiving BYL719 QD at 90 mg (n=3), 180 mg (n=4), 270 mg (n=5), 350 mg (n=5), or 400 mg (n=7). DLTs occurred in 2 out of 4 evaluable patients at 400 mg QD (both had Grade [G] 3 maculopapular rash). Nineteen (79%) patients discontinued treatment [5 due to adverse event (AE); 11 disease progression; 2 patient/guardian decision; 1 death (due to disease progression)]. Median duration of exposure was 7.6 (range: 2.4-55.9) weeks. The most common suspected BYL719-related all-grade AEs (>25%) were maculopapular rash (50%), diarrhea (42%), hyperglycemia (38%), decreased appetite (29%), and pruritus (29%), and G3/4 AEs (≥10%) were maculopapular rash (29%) and hyperglycemia (13%). After May 20, 2013, one additional patient was enrolled at 350 mg QD, and no DLTs were observed out of 6 evaluable patients. Based on the Bayesian logistic regression model, 380 mg QD was the next recommended dose; however, considering the DLTs observed at 400 mg QD, 350 mg QD was declared as the RP2D. One patient with uterine clear cell carcinoma receiving 350 mg QD had an unconfirmed partial response. A dose-dependent increase of plasma exposure was observed and accumulation ratios were generally Conclusions: In this Phase l, first-in-Japanese patients study of BYL719, 350 mg QD was declared as the RP2D and preliminary antitumor activity was observed. An expansion cohort is open at the RP2D in patients whose tumors harbor PIK3CA alterations. Citation Information: Mol Cancer Ther 2013;12(11 Suppl):B188. Citation Format: Yoshihito Kogure, Yasuhide Yamada, Hideo Saka, Chiyoe Kitagawa, Satoru Iwasa, Noboru Yamamoto, Takuji Aoki, Tomoyuki Kakizume, Matthew Robson, Cornelia Quadt, Ayako Mitsuma, Takashi Shibata, Yuichi Ando. A Phase l study of BYL719, an α-isoform selective PI3K inhibitor, in Japanese patients with advanced solid malignancies. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr B188.

Defining predictive biomarkers and deriving appropriate patient populations for treatment are key areas of interest in the clinical development of phosphatidyl-inositol-3-kinase (PI3K) inhibitors, but currently most clinical trials do not pre-select patients using defined genetic markers. Pre-clinical studies indicated previously that in vitro sensitivity to BYL719, a potent and selective small molecule inhibitor of the α-isoform of PI3K, was increased in cell lines derived from a subset of indications, such as HER2-positive or luminal breast cancer. Moreover, BYL719 sensitivity in vitro was positively correlated with PIK3CA mutation or amplification and HER2 amplification. PTEN or BRAF mutation, on the other hand, was associated with BYL719 insensitivity. Consequently, presence of an activating PIK3CA alteration in the tumor was a pre-requisite for patients to enroll into the BYL719 first-in-human (FIM) clinical trial. In this study, we applied massive parallel sequencing to tumor specimens from patients enrolled in the BYL719 FIM trial to comprehensively assess the genetic determinants of clinical sensitivity to BYL719. Paraffin-embedded formalin-fixed archival or pre-treatment tumor specimens were obtained from 44 patients with advanced solid tumors upon enrolment into the clinical trial. DNA was isolated and then assayed by massive parallel sequencing covering either a panel of 182 cancer-related genes at Foundation Medicine or the whole exome at the Broad Institute. Mutations were identified by focusing on genes with alterations in the COSMIC data base and excluding germline variants and were subsequently correlated with clinical benefit as defined by stable disease ≥ 4 months, tumor shrinkage ≥ 20% or objective tumor response to BYL719 using a two-tailed Fisher's exact test. Focusing on a panel of 51 genes with known relevance to PI3K signaling, we observed that all pre-treatment tumor samples harbored at least one genetic abnormality and that each of the genes was altered in one or several tumor samples. TP53 (59%), APC (25%), KRAS (23%) and PTEN (18%) were the most frequently altered in addition to PIK3CA. Alterations in TP53 and KRAS were identified as statistically significant negative predictors of BYL719 sensitivity (p < 0.05), while mutations in the APC and PTEN genes were associated with a trend towards lack of benefit from treatment with BYL719. Our results suggest that definition of the genetic biomarkers that govern sensitivity to treatment with BYL719 and–most likely–other PI3Kα inhibitors in the clinic is possible upon analysis of patient's tumors by massive parallel sequencing. We also demonstrate that it is feasible to routinely obtain this information in the clinical trial setting. This implies that exploration of the genetic determinants driving sensitivity or primary resistance to targeted agents in general can now be undertaken clinically. Citation Format: Jordi Rodon, Dejan Juric, Ana-Maria Gonzalez-Angulo, Johanna Bendell, Jordan Berlin, Douglas Bootle, Kathlene Gravelin, Alan Huang, Adnan Derti, Joseph Lehar, Jens Würthner, Markus Boehm, Eliezer van Allen, Nikhil Wagle, Levi A. Garraway, Roman Yelensky, Philip J. Stephens, Vincent A. Miller, Robert Schlegel, Cornelia Quadt, José Baselga. Towards defining the genetic framework for clinical response to treatment with BYL719, a PI3Kalpha-specific inhibitor. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr LB-65. doi:10.1158/1538-7445.AM2013-LB-65

508 Background: Alterations in the PI3K/AKT/mTOR pathway have been implicated in resistance to trastuzumab (T) in HER2+ breast cancer. BEZ235, a potent oral dual PI3K/mTORC1/2 inhibitor, has demonstrated growth inhibition and apoptosis in HER2+ breast cancer models, including those harboring PI3K pathway alterations, and with T resistance. In a Phase I study, BEZ235 was well tolerated as a single agent in pts with advanced solid tumors. The aim of this study was to determine the MTD of BEZ235 in combination with T in pts with T-resistant HER2+ metastatic breast cancer (mBC) with alterations of the PI3K pathway. Methods: Pts with T-resistant HER2+ mBC (i.e. disease progression during adjuvant therapy or metastatic disease on therapy with T) received oral BEZ235 daily, with weekly T (2 mg/kg). Pts were eligible for enrollment if a tumor sample was demonstrated to contain a molecular alteration of PIK3CA and/or PTEN. Dose escalation was guided by a Bayesian logistic regression model with overdose control. Results: As of 23 Sep 2011, 15 of the 19 enrolled pts were evaluable for dose escalation analysis. BEZ235 was evaluated at 3 dose levels: (1) 400 mg/day (3 pts); (2) 600 mg/day (6 pts); (3) 800 mg/day (10 pts), administered either in capsule form (400 mg) or in sachet form (600 mg and 800 mg). The MTD of BEZ235 in combination with T was estimated to be 600 mg/day. Observed DLTs were G3 nausea at 600 mg/day (1 pt), and G3 nausea, G3 fatigue and G3 skin rash (1 pt each) at 800 mg/day. The most frequent G3/4 adverse events (CTCAE v3.0) suspected to be related to study treatment were diarrhea (4 pts) and nausea (2 pts). No deaths related to study treatment occurred. 1 pt with lung and brain metastases had a partial response. 4 pts had disease stabilization for ≥4 cycles (16 weeks), including 1 pt with liver metastases, in whom BEZ235/T treatment resulted in disease stabilization for more than 21 cycles (84 weeks). Conclusions: BEZ235in combination with T demonstrated an acceptable safety profile in pts with HER2+ mBC and PI3K pathway alterations. Following the Bayesian model recommendation, the MTD for BEZ235 in combination with T was estimated to be 600 mg/day. The safety expansion arm is ongoing at the MTD.

Most of the current oncology drug discovery and development work has shifted towards molecularly targeted therapies. A key focus has been on identifying inhibitors against components of pathways that drive tumor cell proliferation, survival, and metastasis such as the PI3K/mTOR pathway, reported to be implicated in many human cancers through various mechanisms, such as, somatic PIK3CA missense mutations that occur at high frequency. These mutations are largely point mutations predominantly clustered within three hotspots in the helical and kinase domains of p110α: E542K, E545K and H1047R, which represent about 80% of the mutations observed, and confirmed to be oncogenic gain-of-function mutations. Based on these findings cancer-specific mutants of p110α appear to be ideal targets for drug development and p110α specific inhibitors, such as NVP-BYL719, could then have potential anti-cancer activity without causing the potential side effects that could be expected from interference with other Class I PI3K isoforms or other members of the PIKK family. NVP-BYL719 is best described as a PI3Kalpha inhibitor as in biochemical assays, it inhibits p110α as well as p110α most common somatic mutations (IC50=5 nM) much more potently than p110α and ≤ and has weak or no activity against p110α, Vps34 and mTOR and is selective against a wide range of protein kinases (> 50-fold). The potency and selectivity profile of NVP-BYL719 is confirmed at the cellular level, is correlated with inhibition of various PI3K/Akt downstream signaling pathway components and is associated with anti-proliferation of breast cancer cell lines harboring PIK3CA mutations. In vivo, NVP-BYL719 shows dose and time-dependent inhibition of the PI3K/Akt pathway which correlates with compound exposure and is associated with good tolerability and significant dose-dependent anti-tumor efficacy in PIK3CA mutant tumor xenograft models in rodents. Moreover, plasma insulin levels are significantly increased while blood glucose levels remained normal at all tested doses and time points indicating on-target effects of NVP-BYL719 on the regulation of metabolism. Overall, as a PI3Kalpha inhibitor, NVP-BYL719 has good drug-like and pharmacological properties and presents all the characteristics required for its ongoing Phase I clinical development in adult patients with advanced solid malignancies whose tumors have an alteration of the PIK3CA gene. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3748. doi:1538-7445.AM2012-3748