Humanized anti-HER2 Monoclonal Antibody Research Articles

Abstract 2615: Novel combination therapy of adenoviral gene transfer of HER2-extracellular domain and trastuzumab-based photoimmunotherapy for HER2 negative cancer cells

Abstract Introduction: Humanized anti-HER2 monoclonal antibody, trastuzumab, has provided survival benefit to patients with HER2 positive breast cancer and advanced gastric cancer. However, the treatment with trastuzumab was limited due to low or heterogeneous HER2 positivity, insufficient effects as single agent and acquisition of resistance. To overcome these problems, we employed the adenoviral vector expressing HER2-extracellular domain (HER2-ECD), Ad/ HER2-ECD, which is designed to tag cancer cells with HER2-ECD and to sensitize them to trastuzumab, and a novel photoimmunotherapy (PIT). PIT consists of trastuzumab-conjugated with a photosensitizer, IR700 (Tmab-IR700) and irradiation with near-infrared light, induces a strong cytotoxicity on HER2 positive cancer cells. We assessed the effect of Ad/HER2-ECD and Tmab-IR700 mediated PIT in HER2 negative cancer cells. Methods: HER2 negative breast cancer cells (MCF7, MDA-MB-231) and gastric cancer cells (MKN1 and MKN45) were infected with Ad/ HER2-ECD. They were treated with Tmab-IR700 mediated PIT. We evaluated the HER2-ECD expression induced by Ad/ HER2-ECD and the cytotoxic effects of Tmab-IR700 mediated PIT. Results: Ad/HER2-ECD efficiently expressed HER2 protein on the surface of the cancer cells. HER2-ECD expressing cells were selectively and rapidly killed by Tmab-IR700 mediated PIT, which was morphologically captured as bleb formation of cellular membrane. Conclusions: We demonstrated that Ad/ HER-ECD combined with Tmab-IR700 mediated PIT could induce target-selective, immediate cell death in HER2 negative cancer cells. The combination therapy of adenoviral gene transfer of HER2-ECD and the molecular-target PIT is effective for cancer cells regardless of HER2 expression. Citation Format: Michihiro Ishida, Shunsuke Kagawa, Kyoko Shimoyama, Kiyoto Takehara, Kazuhiro Noma, Shunsuke Tanabe, Hiroshi Tazawa, Junji Matsuoka, Hisataka Kobayashi, Toshiyoshi Fujiwara. Novel combination therapy of adenoviral gene transfer of HER2-extracellular domain and trastuzumab-based photoimmunotherapy for HER2 negative cancer cells. [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 2615. doi:10.1158/1538-7445.AM2014-2615

A phase 1 dose-escalation study of anti-HER3 monoclonal antibody LJM716 in combination with trastuzumab in patients with HER2-overexpressing metastatic breast or gastric cancer.

2519 Background: TheHER2-HER3 heterodimer, a key driver in HER2-positive tumors, is not completely blocked by available therapies. LJM716 is a fully human anti-HER3 monoclonal antibody (mAb) shown ...

Bioorthogonal, two-component delivery systems based on antibody and drug-loaded nanocarriers for enhanced internalization of nanotherapeutics

Nanocarriers play an important role in targeted cancer chemotherapy. The optimal nanocarrier delivery system should provide efficient and highly specific recognition of the target cells and rapid internalization of the therapeutic cargo to reduce systemic toxicity as well as to increase the cytotoxicity to cancer cells. To this end, we developed a two-step, two-component targeted delivery system based on antibody and drug-loaded nanocarrier that uses bioorthogonal click reactions for specific internalization of nanotherapeutics. The pretargeting component, anti-HER2 humanized monoclonal antibody, trastuzumab, functionalized with azide groups labels cancer cells that overexpress HER2 surface receptors. The drug carrier component, dibenzylcyclooctyne substituted albumin conjugated with paclitaxel, reacts specifically with the pretargeting component. These two components form cross-linked clusters on the cell surface, which facilitates the internalization of the complex. This strategy demonstrated substantial cellular internalization of clusters consisted of HER2 receptors, modified trastuzumab and paclitaxel-loaded albumin nanocarriers, and subsequent significant cytotoxicity in HER2-positive BT-474 breast cancer cells. Our results show high efficacy of this strategy for targeted nanotherapeutics. We foresee to broaden the applications of this strategy using agents such as radionuclides, toxins, and interfering RNA.

Abstract P4-16-09: Phase 1b/2 trial of the HER3 inhibitor patritumab (U3-1287) in combination with trastuzumab plus paclitaxel in newly-diagnosed patients with HER2+ metastatic breast cancer (MBC)

Abstract Background: Patritumab is a fully human anti-HER3 monoclonal antibody that has shown potent antitumor activity in vivo. HER3 is a key dimerization partner for other HER family members, and studies suggest that the HER3:HER2 heterodimer is the most potent signaling pair. Therefore, combined inhibition of HER3 and HER2 may synergistically inhibit breast cancer tumor growth. In the CLEOPATRA trial, pertuzumab combined with trastuzumab and docetaxel prolonged progression-free survival compared to trastuzumab and docetaxel alone, demonstrating the benefit of comprehensive blockade of HER2 dimer signaling. Trastuzumab is approved in combination with paclitaxel for first-line treatment of HER2+ MBC. This phase 1b/2 study is investigating patritumab in combination with trastuzumab and paclitaxel in patients (pts) with newly-diagnosed MBC. Results of the phase 1b portion are reported here. Methods: Eligible pts had HER2+ newly-diagnosed MBC. In the open-label, phase 1b portion of this trial, pts received intravenous (IV) patritumab 18 mg/kg in combination with trastuzumab (8 mg/kg IV loading dose; 6 mg/kg IV maintenance dose) and paclitaxel (175 mg/m2 IV) every 3 weeks (Q3W). In the event that 18 mg/kg was not tolerated based on dose-limiting toxicity (DLT) assessment, sequential cohorts were to receive de-escalating doses of patritumab. Phase 1b study end points included adverse event (AE) incidence, human antihuman antibody (HAHA) formation, pharmacokinetics (PK), and tumor response. Results: Six pts were enrolled in the phase 1b portion of the trial, with a median age of 61 years (range, 51-78). There were no reported DLTs. Grade ≥3 treatment-related AEs occurred in 3 pts: 1 pt had a serious AE of grade 3 pneumonia; 1 pt had grade 3 worsening of arm pain; 1 pt had grade 3 oral mucositis, prolonged QTc, flu-like syndrome, and increased transaminases. In this limited pt population, most ECG changes were within or slightly above normal limits of the QTc interval. Only 2 pts had increased values close to 50 msec compared with baseline. It should be noted that baseline QTc values for 3 pts (including the pt that experienced grade 3 prolonged QTc) were close to the upper limit of normal. There were no grade 4 AEs, and no other serious AEs. All other treatment-related AEs were grades 1 or 2. All 6 pts tested negative for HAHA formation after drug administration. PK data are consistent with previous studies with patritumab. Two pts had complete response (CR) as their best overall response, 2 pts had partial response (PR), 1 pt had stable disease, and 1 pt was not evaluated for tumor response. All 6 pts have discontinued treatment; 2 due to progressive disease, 3 due to pt decision (2 with CR and 1 with PR), and 1 at the investigator's discretion. Conclusions: Results to date indicate that the combination of patritumab with trastuzumab and paclitaxel is generally well tolerated, with a promising response rate. As no DLTs were reported, the recommended phase 2 dose is patritumab 18 mg/kg with trastuzumab (8 mg/kg loading; 6 mg/kg maintenance) and paclitaxel 175 mg/m2 Q3W. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P4-16-09.

Abstract A67: Phase I study of HER3 targeted antibody patritumab (U3-1287) in combination with erlotinib in Japanese patients with non-small cell lung cancer (NSCLC).

Abstract Background: HER3 is a key dimerization partner for HER-family members that activates oncogenic signaling pathways. Patritumab is a fully human anti-HER3 monoclonal antibody that has demonstrated anticancer activity in preclinical models. In a preceding Japanese Phase I study in patients with advanced solid tumors, the tolerability of U3-1287 was confirmed up to the dose of 18 mg/kg without dose-limiting toxicities (DLTs). This study aimed to assess the safety, pharmacokinetics, and recommended dose of U3-1287 in combination with erlotinib for Japanese patients with advanced NSCLC. The incidence of anti-U3-1287 antibodies (HAHA), tumor response, and level of serum soluble HER3 (sHER3) were also evaluated. Methods: This study enrolled stage IIIB/IV NSCLC patients who had progressed after at least one prior chemotherapy. This study consisted of 2 parts; dose escalation (Part 1) and dose expansion (Part 2). Patients in Part 1 received patritumab 9 mg/kg or 18 mg/kg every 3 weeks (q3w) i.v., in addition to erlotinib 150 mg/day daily p.o. DLTs were assessed in Part 1. In Part 2, patients received the recommended dose of patritumab in combination with erlotinib determined in Part 1. Results: Twenty-four patients, 6 in Part 1 and 18 in Part 2, were enrolled. Thirteen patients had activating epidermal growth factor receptor (EGFR) mutation (12 out of 13 patients received prior gefitinib therapy), 9 had wild type EGFR, and 2 had unknown status. The most common (≥ 50% overall) adverse events were diarrhea (95.8%), stomatitis (91.7%), paronychia (83.3%), dermatitis acneiform (70.8%), dry skin (62.5%), decreased weight (54.2%), and decreased appetite (50.0%), which were generally mild and manageable. Serious adverse events (SAEs) were reported in 4 patients; hepatic dysfunction, bacterial infection, pneumonia, cancer pain, and rash acneiform. All SAEs except for cancer pain were considered to be related to both patritumab and erlotinib treatment. No DLTs were observed. One patient with activating EGFR mutations achieved partial response and 13 patients including 10 patients with activating EGFR mutations had stable disease. The median progression-free survivals were 46.0 days at 9 mg/kg (n =3), 91.0 days at 18 mg/kg (n = 21), 44.0 days for the wild type EGFR (n= 9) and 107.0 days for the activating EGFR mutations (n = 13). One patient had positive HAHA immunoassay results and the samples were also evaluated using the cell-based bioassay. However, no neutralizing antibodies were detected. The level of sHER3 increased after patritumab administration in all subjects. These changes did not correlate with the dose level of patritumab. Conclusions: The tolerability of patritumab with erlotinib has been confirmed up to the dose of 18 mg/kg of U3-1287 in Japanese patients with advanced NSCLC. Citation Information: Mol Cancer Ther 2013;12(11 Suppl):A67. Citation Format: Noboru Yamamoto, Atsushi Horiike, Makoto Nishio, Haruyasu Murakami, Nobuyuki Yamamoto, Hiroyasu Kaneda, Kazuhiko Nakagawa, Tomohide Tamura. Phase I study of HER3 targeted antibody patritumab (U3-1287) in combination with erlotinib in Japanese patients with non-small cell lung cancer (NSCLC). [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 A67.

O2–096 - Phase I Study of Patritumab (U3-1287) in Combination with Erlotinib in Japanese Patients with Non-Small Cell Lung Cancer

Background: HER3 is a key dimerization partner for HER-family members that activates oncogenic signaling pathways. U3-1287 is a fully human anti-HER3 monoclonal antibody that has demonstrated anticancer activity in preclinical models. In a preceding Japanese phase I study, the tolerability of U3-1287 was evaluated up to the dose of 18 mg/kg without dose-limiting toxicities (DLTs). This study aimed to assess the safety, pharmacokinetics and recommended dose of U3-1287 in combination with erlotinib for Japanese patients with advanced non-small cell lung cancer (NSCLC).

Clinical practice-changing trials: the HERA study paradigm

Trastuzumab, a humanized anti-HER2 monoclonal antibody targeting the extracellular domain of this oncoprotein, represents the archetype of HER2 blocking agents. Its unprecedented efficacy for HER2-positive metastatic breast cancer (BC) led to its clinical development in the adjuvant setting. The HERceptin Adjuvant (HERA) is one of the pivotal adjuvant trastuzumab trials which proved that this compound can change the natural course of early stage HER2-positive BC. The HERA study led to the registration of trastuzumab for the adjuvant treatment of early HER2-positive BC. This trial randomized more than 5000 patients between 1 and 2 years of trastuzumab and observation after the completion of locoregional therapy and (neo)-adjuvant chemotherapy. Additionally, an abundance of subsequent substudies were conducted, addressing important clinical issues for this patient population. The present review article presents a comprehensive overview of the HERA study and its major contributions to the adjuvant treatment of HER2-positive BC patients. Emphasis is given on the lessons learned from this international collaborative experience and how this can be used as a stepping stone for further improvements in the field.Trial registration: ClinicalTrial.gov identifier: NCT00593697.Trial registration: ClinicalTrial.gov identifier: NCT00712140.Trial registration: ClinicalTrial.gov identifier: NCT00629278.Trial registration: ClinicalTrial.gov identifier: NCT00615602.Trial registration: ClinicalTrial.gov identifier: NCT00615602.Trial registration: ClinicalTrial.gov identifier: NCT00490139.Trial registration: ClinicalTrial.gov identifier: NCT01358877.

Pertuzumab: A Review of Its Use for First-Line Combination Treatment of HER2-Positive Metastatic Breast Cancer

Pertuzumab (Perjeta®) is a humanized anti-HER2 monoclonal antibody that binds to the extracellular dimerization subdomain of the HER2 receptor and reduces HER2 intracellular signalling by preventing HER2 from forming heterodimers with other HER receptors. Inhibition of HER2 signalling results in a reduction of tumour cell proliferation, invasiveness and survival. Pertuzumab and trastuzumab bind to different sites on the HER2 receptor and have complementary antitumour activities; they act synergistically in inhibiting the growth of HER2-overexpressing breast cancer cell lines in vitro. The efficacy of intravenous pertuzumab (840 mg loading dose, then 420 mg every 3 weeks) in combination with trastuzumab plus docetaxel in the first-line treatment of HER2-positive metastatic breast cancer was demonstrated in the randomized, double-blind, placebo-controlled, multinational, phase III CLEOPATRA trial. Pertuzumab in combination with trastuzumab and docetaxel significantly increased independently assessed median progression-free survival (primary endpoint), objective response rate and overall survival compared with placebo in combination with trastuzumab and docetaxel. Pertuzumab had an acceptable tolerability profile when added to trastuzumab and docetaxel in the pivotal CLEOPATRA trial. Thus, pertuzumab is a valuable addition to the growing list of anti-HER2 targeted therapies for breast cancer.

Phase I Study of U3-1287, a Fully Human Anti-HER3 Monoclonal Antibody, in Patients with Advanced Solid Tumors

HER3 is a key dimerization partner for other HER family members, and its expression is associated with poor prognosis. This first-in-human study of U3-1287 (NCT00730470), a fully human anti-HER3 monoclonal antibody, evaluated its safety, tolerability, and pharmacokinetics in patients with advanced solid tumor. The study was conducted in 2 parts: part 1--sequential cohorts received escalating doses (0.3-20 mg/kg) of U3-1287 every 2 weeks, starting 3 weeks after the first dose; part 2--additional patients received 9, 14, or 20 mg/kg U3-1287 every 2 weeks, based on observed tolerability and pharmacokinetics from part 1. Recommended phase II dose, adverse event rates, pharmacokinetics, and tumor response were determined. Fifty-seven patients (part 1: 26; part 2: 31) received U3-1287. As no dose-limiting toxicities were reported, the maximum-tolerated dose was not reached. The maximum-administered dose was 20 mg/kg every 2 weeks. The most frequent adverse events related to U3-1287 were fatigue (21.1%), diarrhea (12.3%), nausea (10.5%), decreased appetite (7.0%), and dysgeusia (5.3%). No patient developed anti-U3-1287 antibodies. In these heavily pretreated patients, stable disease was maintained 9 weeks or more in 19.2% in part 1 and 10 weeks or more in 25.8% in part 2. U3-1287 treatment was well tolerated, and some evidence of disease stabilization was observed. Pharmacokinetic data support U3-1287 dosing of 9 to 20 mg/kg every 2 to 3 weeks. Combination studies of U3-1287 are ongoing.

O1-080 - Phase I and Dose Finding Study of U3-1287, a Human Monoclonal Antibody Targeting HER3, in Japanese Patients with Advanced Solid Tumors

ABSTRACT Background HER3 is a key dimerization partner for HER-family members that activates oncogenic signaling pathways lead to cell survival and proliferation. U3-1287 is a fully human anti-HER3 monoclonal antibody that has demonstrated anticancer activity in preclinical models. In a preceding US phase I study, the tolerability of U3-1287 was evaluated up to the dose of 20 mg/kg without dose-limiting toxic effects (DLTs). In this study, we evaluated the tolerability, pharmacokinetics (PK) and potential antitumor activities of U3-1287 in Japanese patients with solid tumors up to the dose of 18 mg/kg. Methods Patients with advanced solid tumors that were well known to express HER3 were eligible (e.g. lung, breast, colorectal, cervical, esophageal, and sarcoma). Patients received U3-1287 9 or 18 mg/kg intravenously every 3 weeks (q3w). The incidence of anti-U3-1287 antibodies (HAHA), tumor response and U3-1287 related biomarkers were also evaluated. Results Nine patients, three at 9 mg/kg and six at 18 mg/kg, were enrolled. Five patients were male, all patients had ECOG PS ≤ 1 and median (range) age was 67 (50–69) years. Primary tumor types were lung (2), colorectal (2), esophageal (2), breast (1), cervical (1) and sarcoma (1). U3-1287-related AEs reported in ≥2 patients were ALT increase (3 patients), platelet count decrease, diarrhea, stomatitis, cheilitis, rash maculo-papular and AST increase (2 each). No DLTs were observed. Plasma disappearance of U3-1287 was bi-phasic and terminal half-life at the dose of 18 mg/kg was approximately 9 days. The PK profile was similar to the US phase I study. Four patients had a best response of stable disease. All patients tested negative for HAHA formation. Conclusions U3-1287 was well tolerated up to 18 mg/kg in Japanese patients with solid tumors. These data support a dosing regimen of 18 mg/kg q3w in future studies.

Targeted treatments of HER2-positive metastatic breast cancer: trastuzumab and beyond

SUMMARY HER2 positivity defines a molecular subtype of breast cancer with aggressive biological behavior. HER2 has been clinically validated as a prominent therapeutic target in breast cancer, and an abundance of data from clinical trials proving the efficacy of trastuzumab, a humanized anti-HER2 monoclonal antibody, has changed the natural history of this disease. Despite positive results from many trials, resistance to anti-HER2 agents inevitably occurs in both the metastatic and adjuvant settings. This clinical reality has led to the development of various other targeted agents designed to block the HER2 receptor. Similarly, attempts to elucidate the molecular mechanisms of resistance to the already established anti-HER2 agents have opened new therapeutic avenues with numerous promising agents. This review presents a comprehensive overview of the data available on anti-HER2-targeted agents other than trastuzumab, and describes both challenges and directions for the future.

467P - Phase I Study of U3-1287, A Human Monoclonal Antibody Targeting Her3, in Japanese Patients with Advanced Solid Tumors

ABSTRACT Background HER3 is a key dimerization partner for HER-family members that activates oncogenic signaling pathways lead to cell survival and proliferation. Acquired-resistance to EGFR inhibitors may result from the activation of HER3 and/or HER2, which share overlapping the signaling pathways. U3-1287 is a fully human anti-HER3 monoclonal antibody that has demonstrated anticancer activity in preclinical models. In a preceding US phase I study, the tolerability of U3-1287 was evaluated up to the dose of 20 mg/kg without dose-limiting toxicities (DLTs). In this study, we evaluated the tolerability, pharmacokinetics (PK) and potential antitumor activities of U3-1287 in Japanese patients with solid tumors up to the dose of 18 mg/kg. Methods Patients received U3-1287 at a dose of 9 mg/kg or 18 mg/kg intravenously every 3 weeks (q3w). Tumor response, incidence of anti-U3-1287 antibodies (HAHA), and level of soluble HER3 (sHER3) were also evaluated. Results Nine patients, 3 at 9 mg/kg and 6 at 18 mg/kg, were enrolled. Five patients were male and median (range) age of 67 (50-69) years. Tumor types were lung (2), colorectal (2), esophageal (2), breast (1), cervical (1), and sarcoma (1). No DLTs were reported. U3-1287-related AEs were ALT increase (3 patients), thrombocytopenia, diarrhea, stomatitis, cheilitis, rash, and AST increase (2 each). Plasma disappearance was bi-phasic and terminal half-life at the dose of 18 mg/kg was approximately 9 days. PK profiles were similar to those in the US phase I study. Four patients had best responses of stable disease. All patients tested were negative for HAHA formation. Level of sHER3 unexpectedly increased about four times in all patients. Mean sHER3 concentrations at baseline and day 15 were 3.8 ng/mL and 16.5 ng/mL, respectively. These changes did not correlate with clinical response (at day15 in SD and PD patients; 16.7 ng/mL and 16.9 ng/ml, respectively). Conclusions U3-1287 was well tolerated up to 18 mg/kg in Japanese patients with solid tumors. These data support a dosing regimen of 18 mg/kg q3w in future studies. Disclosure All authors have declared no conflicts of interest.

Abstract PR6: Phase 1b/2 trial of HER3 inhibitor U3-1287 in combination with erlotinib in advanced NSCLC patients (pts): HERALD study

Abstract Background: EGFR is frequently overexpressed in NSCLC, and while many advanced NSCLC tumors initially respond to EGFR tyrosine kinase inhibitors (TKIs), development of therapeutic resistance often follows. HER3 is a key dimerization partner of HER family members, including EGFR, and activates oncogenic signaling pathways. HER3 overexpression occurs in many solid tumors and is associated with poor prognosis in lung cancer pts. Data indicate that HER3 expression may play a role in EGFR TKI resistance, suggesting that simultaneous inhibition of HER3 and EGFR may be beneficial. U3-1287 is a fully human anti-HER3 monoclonal antibody with synergistic anticancer activity in combination with anti-EGFR inhibitors in preclinical models. The phase 1b/2 HERALD trial was initiated to investigate the combination of U3-1287 with erlotinib in the treatment of advanced NSCLC pts after failure of at least 1 prior chemotherapy. Results as of August 12, 2011 are reported here. Methods: Eligible pts had stage IIIB/IV NSCLC that progressed on ≥1 prior chemotherapy treatments and were EGFR treatment-naive. In the open-label, phase 1b portion, pts received erlotinib 150 mg/day orally and U3-1287 18 mg/kg intravenously every 3 weeks (Q3W). In the event that 18 mg/kg was not tolerated based on DLT assessment, sequential cohorts were to receive de-escalating doses of U3-1287. As no DLTs were reported, the recommended phase 2 dose is 18 mg/kg Q3W for U3-1287 in combination with 150 mg/day erlotinib. The phase 2 portion of the study is a randomized, placebo-controlled, double-blind study assessing the efficacy and safety of U3-1287 combined with erlotinib relative to erlotinib alone. It is a 3-arm study of 150 mg/day erlotinib with U3-1287 high-dose (18 mg/kg Q3W), U3-1287 low-dose (18 mg/kg loading dose followed by 9 mg/kg Q3W), or placebo. Study end points include adverse event (AE) incidence, pharmacokinetics, human antihuman antibody (HAHA) formation, tumor response, and progression-free survival (PFS). Results: The phase 1b portion of the trial enrolled 7 pts (4 male), with a median age of 68 years (range, 48–78). There were no reported DLTs. Erlotinib-related AEs reported in ≥2 pts were rash (6 pts), diarrhea (4), dry skin (3), decreased appetite (3), stomatitis (3), dehydration, dermatitis acneiform, dysgeusia, mucosal inflammation, nausea, and skin exfoliation (2 each). The only U3-1287–related AE reported in ≥2 pts was decreased appetite (2 pts). AEs grade ≥3 occurred in 2 pts: one grade 3 case each of pain, fatigue, headache, dehydration, diarrhea, and blood creatinine increase; none were related to U3-1287. Three pts had 3 serious AEs: grade 3 pain (unrelated to study treatment), grade 3 dehydration (erlotinib-related), and grade 1 decreased appetite (erlotinib- and U3-1287-related). All seven pts tested negative for HAHA formation after drug administration. As of Aug 12, 3 pts have ended study treatment due to disease progression. Four pts had best responses of stable disease lasting 86, 87, 90, and 117 days. As of Aug 12, in the phase 2 portion, 11 pts (4 male) have been screened; first study treatment was June 21. Pts had a median age of 70 years (range, 49–83). There have been 2 serious AEs in 1 pt, both unrelated to study treatment: grade 2 cardiac disorder requiring hospitalization and death due to multi-organ failure. Treatment-related AEs reported were diarrhea (3 pts), rash (3), cardiac disorder, decreased appetite, nausea, and vomiting (1 each); all were grade 1 or 2. Conclusions: Results across the phase 1b and 2 portions indicate that U3-1287 in combination with erlotinib is generally well tolerated. This abstract is also presented as Poster B38.

Pertuzumab plus Trastuzumab plus Docetaxel for Metastatic Breast Cancer

BackgroundThe anti–human epidermal growth factor receptor 2 (HER2) humanized monoclonal antibody trastuzumab improves the outcome in patients with HER2-positive metastatic breast cancer. However, most cases of advanced disease eventually progress. Pertuzumab, an anti-HER2 humanized monoclonal antibody that inhibits receptor dimerization, has a mechanism of action that is complementary to that of trastuzumab, and combination therapy with the two antibodies has shown promising activity and an acceptable safety profile in phase 2 studies involving patients with HER2-positive breast cancer.MethodsWe randomly assigned 808 patients with HER2-positive metastatic breast cancer to receive placebo plus trastuzumab plus docetaxel (control group) or pertuzumab plus trastuzumab plus docetaxel (pertuzumab group) as first-line treatment until the time of disease progression or the development of toxic effects that could not be effectively managed. The primary end point was independently assessed progression-free survival. Secondary end points included overall survival, progression-free survival as assessed by the investigator, the objective response rate, and safety.ResultsThe median progression-free survival was 12.4 months in the control group, as compared with 18.5 months in the pertuzumab group (hazard ratio for progression or death, 0.62; 95% confidence interval, 0.51 to 0.75; P<0.001). The interim analysis of overall survival showed a strong trend in favor of pertuzumab plus trastuzumab plus docetaxel. The safety profile was generally similar in the two groups, with no increase in left ventricular systolic dysfunction; the rates of febrile neutropenia and diarrhea of grade 3 or above were higher in the pertuzumab group than in the control group.ConclusionsThe combination of pertuzumab plus trastuzumab plus docetaxel, as compared with placebo plus trastuzumab plus docetaxel, when used as first-line treatment for HER2-positive metastatic breast cancer, significantly prolonged progression-free survival, with no increase in cardiac toxic effects. (Funded by F. Hoffmann–La Roche/Genentech; ClinicalTrials.gov number, NCT00567190.)

OT1-02-13: Cardiac Biomarkers on Trastuzumab (Cabot Trial): Determining the Cardiac Biomarker Profile in Breast Cancer Patients Receiving Adjuvant Trastuzumab Therapy.

Abstract Background Trastuzumab is a humanized anti-HER2 monoclonal antibody that has demonstrated a 50% reduction in the risk of HER2+ breast cancer recurrence. This benefit is at the risk of possible cardiac dysfunction. Detecting trastuzumab-related cardiotoxicity based on physical examination and assessment of left ventricular ejection fraction (LVEF) by serial echocardiography or multi gated acquisition (MUGA) scan, has low diagnostic sensitivity and low predictive power in detecting subclinical myocardial injury. There is interest in developing simple, non-invasive, and cost-effective tools for early identification of trastuzumab-related cardiotoxicity. Use of easily detectible cardiac biomarkers in blood, such as cardiac troponins (cTnT and cTnI) and natriuretic peptides (NPs), are being evaluated. Kavsak et al. have studied a high-sensitivity cTn (hs-cTn) assay that is 10-fold more sensitive, and may be able to identify evolving injury earlier when compared to the conventional cTn assays. B-type natriuretic peptide (BNP) has been established as an indicator for heart failure. Pro-BNP is secreted from the cardiac ventricles in response to increased pressure and volume and is divided into NT-pro-BNP and BNP. The longer half-life of NT-proBNP may make it a more accurate predictor of ventricular stress. Trial design: This is a pilot single institution, prospective cohort study of 25 patients. Breast cancer patients will be seen at the Juravinski Cancer Centre, Hamilton, Canada. Biomarkers will be collected at baseline, then days 1 and 2 of every 21 day cycle for the first 3 months, then every 42 days for the next 3 months. LVEF will be measured at baseline and then every 3 months while on trastuzumab. Eligibility criteria: Patients with stage I-III, HER2 positive (3+ by immunohistochemistry or FISH+) breast cancer receiving adjuvant trastuzumab therapy. Patients who have received prior trastuzumab therapy or are unable to provide informed consent will be excluded. Specific aims: To determine the biological profile of cardiac biomarkers — cTnT, hs-cTn, and NT-proBNP — in patients on adjuvant trastuzumab; and, to determine if elevations in these biomarkers correlate with LVEF. Statistical methods: A convenient sample size of 25 patients will be entered into this pilot study. The minimum of 20 patients is a requirement by the Clinical Laboratory Standards Institute (CLSI) to formally accept existing reference ranges for the cardiac biomarkers to be used in the HER2 breast cancer population (National Committee for Clinical Laboratory Standards (NCCLS)). Present accrual and target accrual: 8 patients have enrolled to date. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr OT1-02-13.

OT1-02-04: Adjuvant Pertuzumab and Herceptin IN IniTial TherapY of Breast Cancer: APHINITY (BIG 4–11/BO25126/TOC4939g).

Abstract Background Approximately 20% of breast cancer (BC) patients (pts) have HER2−positive tumors. While the adjuvant use of the anti-HER2 humanized monoclonal antibody trastuzumab (T) has been shown to improve disease-free (DFS) and overall survival (OS), not all pts treated with this agent benefit from this therapy. Pertuzumab (P) is a humanized monoclonal antibody that inhibits HER2 dimerization and induces ADCC with a complementary mechanism of action to T. In HER2−positiveadvanced BC, T and P is active in pts who have progressed to T. In the neoadjuvant setting, T and P in combination with chemotherapy (CT) nearly doubled the pathological complete response rate compared to either T or P administered in combination with CT (45.8% vs 29% vs 24%, respectively). Therefore, comprehensive HER2 blockade with two anti-HER2 monoclonal antibodies warrants further investigation in the adjuvant setting. Trial Design: APHINITY is a prospective, randomized, multicenter, double-blind, placebo-controlled study in pts with HER2−positive primary BC who have had an excision of their tumor. Pts will be randomized to one of 2 arms (1:1 ratio). The investigational arm will comprise of a course of adjuvant CT (investigators choice) consisting of either an anthracycline-taxane or taxane-platin containing regimens and T and P for 1 year. The comparator arm will consist of the same adjuvant CT backbone with T and placebo for 1 year. Major Eligibility Criteria: 1. Non-metastatic primary BC histologically confirmed and adequately excised 2. Node-positive or node-negative: for patients with node-positive disease (pN ≥1), any pT except T0; for patients with node-negative disease (pN0), tumor size must be &amp;gt;1.0 cm OR for tumor size between &amp;gt;0.5 cm and ≤1.0 cm, at least one of the following features will be required: histologic grade 3 OR negative for ER and PgR OR age &amp;lt;35 years 3. The interval between definitive surgery for BC and randomization must be at least 3 weeks but no more than 7 weeks 4. Baseline LVEF ≥55% 5. HER2−positive BC confirmed by a central laboratory and defined as: IHC 3+ in &amp;gt;10% immunoreactive cells OR HER2 gene amplification by in situ hybridization [ISH] (ratio of HER2 gene signals to centromere 17 signals ≥2) Aims: The primary objective is to compare invasive disease-free survival (IDFS) between both treatment arms. Secondary objectives include comparing IDFS including second non-BC, DFS, OS, recurrence-free interval (RFI), distant RFI, cardiac safety, overall safety and health-related quality of life in the two treatment arms. Statistical Methods: Pts will be stratified based on nodal status, type of adjuvant CT regimen, hormone receptor status and geographical region. The study is designed to have an 80% power to test the null hypothesis of no true difference in risk of an IDFS event (HR = 1) versus the alternative hypothesis of a difference (HR = 0.75) in hazard rates with a 5%, 2-sided significance level. Target accrual: 3806; Present accrual: Start Q4 2011 Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr OT1-02-04.

Abstract A187: A phase 1b/2 trial of U3–1287, a HER3 inhibitor, in combination with erlotinib in patients (pts) with advanced NSCLC.

Abstract Background: EGFR is frequently overexpressed in NSCLC, particularly in adenocarcinomas. Many advanced NSCLCs initially respond to EGFR tyrosine kinase inhibitors (TKIs) but subsequently develop resistance. HER3 is a key dimerization partner of HER family members, including EGFR, and activates oncogenic signaling pathways. Overexpression of HER3 occurs in many solid tumors and is associated with poor prognosis in lung cancer pts. Data suggest that HER3 expression may play a role in EGFR TKI resistance, suggesting that simultaneous inhibition of HER3 and EGFR may offer therapeutic benefit. U3–1287 is a fully human anti-HER3 monoclonal antibody with synergistic anticancer activity in combination with anti-EGFR inhibitors in preclinical models. A phase 1b/2 trial was initiated to investigate the combination of U3–1287 with the EGFR TKI erlotinib in the treatment of advanced NSCLC pts. We report here the results of the phase 1b portion as of June 13, 2011. Materials and Methods: To be eligible, pts had to have stage IIIB/IV NSCLC that had progressed on ≥1 prior chemotherapy treatments and were EGFR treatment-naive. In the open-label, phase 1b portion of the study, pts received erlotinib 150 mg/day orally and U3–1287 18 mg/kg intravenously every 3 weeks (Q3W). The U3–1287 dose was selected on the basis of results from the first-in-human phase 1 study (ENA 2010, abstract 234) in which no dose-limiting toxicities (DLTs) were observed up to the maximum administered dose of 20 mg/kg Q2W. In the event that 18 mg/kg was not tolerated based on DLT assessment, sequential cohorts were to receive de-escalating doses of U3–1287. DLTs included any treatment-related grade ≥3 toxicity except for anorexia, grade 3 fatigue persistent ≥7 days, nausea/vomiting in the absence of standard anti-emetic therapy, and lymphopenia. Phase 1b study end points included adverse event (AE) incidence, pharmacokinetics, and tumor response. Results: Seven pts (4 male) enrolled in the phase 1b portion of the trial, with a median age of 68 years (range, 48–78). Five pts had adenocarcinoma, and 2 pts had squamous carcinoma. Pts had 1, 2, or 3 prior NSCLC therapies (n=4, 2, and 1, respectively). There were no reported DLTs. Erlotinib-related AEs reported in ≥2 pts were rash (6 pts), diarrhea (4), dry skin (3), decreased appetite, dehydration, dermatitis acneiform, dysgeusia, mucosal inflammation, nausea, skin exfoliation, and stomatitis (2 each). No U3–1287-related AEs were reported in &amp;gt;1 pt; those that occurred in 1 pt each were increases in blood creatinine and urea, decreased appetite, diarrhea, dysgeusia, mucosal inflammation, nausea, proteinuria, rash, ventricular extrasystoles, and vomiting. AEs grade ≥3 occurred in 2 pts, and included a grade 3 case each of pain, fatigue, headache, dehydration, diarrhea, and increase in blood creatinine; none were related to U3–1287. One pt had grade 3 diarrhea and a serious AE of grade 3 dehydration requiring hospitalization after the DLT observation period (cycle 1); both AEs were erlotinib-related. All other treatment-related AEs were grades 1 or 2. At the week-6 visit, 4 pts had stable disease, and 3 had progressive disease. Conclusions: Results to date indicate that the combination of U3–1287 with erlotinib is generally well tolerated. As no DLTs were reported, the recommended phase 2 dose is 18 mg/kg Q3W for U3–1287 in combination with 150 mg/day erlotinib. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr A187.

Comparison of Photostability and Photobleaching Properties of FITC- and Dylight488- Conjugated Herceptin

ABSTRACT Nowadays, fluorescent dyes have become significant tools in immunostaining experiments. Different fluorescent dyes have various physicochemical traits. Some of these traits, for instance photobleaching and photostability, are applicable calibers in such experiments as immunocytochemistry (ICC), immunohistochemistry (IHC), and flow cytometry (FC). In this study, photobleaching, photostability, and mean fluorescence intensity (MFI) of FITC (fluorescein isothiocyanate)- and Dylight488- conjugated Herceptin, the humanized anti Her2 monoclonal antibody drug, were examined. After conjugation of FITC and Dylight488 to Herceptin, their degree of labeling (DOL) was calculated by a spectrophotometer. Photobleaching, photostability, and MFI of conjugates were subsequently investigated by ICC and FC on BT-474 cells. Dylight488 labeled Herceptin revealed higher fluorescent lifetime and photostability than FITC conjugated Herceptin.

A first-in-human phase I study of U3-1287 (AMG 888), a HER3 inhibitor, in patients (pts) with advanced solid tumors.

3026 Background: Human epidermal growth factor receptor 3 (HER3) is a key dimerization partner for the HER family and activates oncogenic signaling pathways. Its overexpression in many solid tumors has been linked to poor prognosis. U3-1287 (AMG 888) is a fully human anti-HER3 monoclonal antibody with demonstrated anticancer activity in preclinical models. This study had 2 parts: based on the observed tolerability of ≤20 mg/kg and pharmacokinetics (PK) study from the dose-escalation phase (part 1), 9, 14, and 20 mg/kg Q2W dosages were given in the dose-expansion phase (part 2). Methods: Pts with non–small cell lung cancer (NSCLC) and other refractory solid tumors thought to express HER3 were eligible. Study assessments included adverse event (AE) rates, PK, and tumor response (per modified RECIST and overall metabolic tumor response by EORTC). Human antihuman antibody (HAHA) responses were measured to assess immunogenicity. Results: Part 2 data (as of 9/24/10) are reported. Pts (N=31) with head and neck (1 pt), breast (1), ovary (1), cecum/appendix (1), colorectal cancer (CRC, 10), and NSCLC (17) tumor types were given 9 (n=10), 14 (n=2), and 20 mg/kg (n=19) of U3-1287 (AMG 888). Pts had a median (range) of 5 (2–10) prior chemotherapy regimens. 11 serious AEs were reported in 10 pts; none were attributable to U3-1287 (AMG 888). 16 pts (51.6%) experienced AEs ≥ grade (Gr) 3, with 1 Gr 5 dyspnea and 1 Gr 4 hypoglycemia. Two AEs ≥ Gr 3 were considered drug-related: Gr 3 anemia and Gr 3 rash. Gr 1/2 drug-related AEs in ≥10% of pts were fatigue, diarrhea, and nausea. Of 21 pts assessed, no HAHA responses were observed (by 21 days postdose). PK analysis (n=15) showed that steady state is reached after 3 dosing cycles for pts receiving 9, 14, or 20 mg/kg. Mean steady state Cmin was >10-fold greater than the threshold concentration required for 90% HER3 inhibition in xenograft models. Eight pts (6 NSCLC, 2 CRC) had a best response of stable disease at or beyond day-70 visit. One pt (NSCLC, 20 mg/kg) had significant tumor shrinkage (26.3%) and partial metabolic response by FDG-PET scan. Conclusions: U3-1287 (AMG 888) is well tolerated, with an absence of detectable HAHA responses. Part 2 data support 9–20 mg/kg Q2W dosage for future studies.

HER2 Testing in Gastric Cancer

Molecular therapies targeting HER2 are part of the established drug armamentarium in breast carcinoma. Now the ToGA trial, an international multicenter phase III clinical study, involving 24 countries globally, has shown that the anti-HER2 humanized monoclonal antibody Trastuzumab is effective in prolonging survival in HER2-positive carcinoma of the stomach and the gastroesophageal junction (GEJ). Similarly to breast carcinoma, >20% of gastric cancers show HER2 overexpression and/or amplification, and this percentage increases to 33% in GEJ tumors. Thus, as in breast carcinoma, pathologists are now asked to evaluate HER2 status in gastric carcinoma samples. As validated in the ToGA trial, the HER2 testing criteria that must be used in evaluating both gastric carcinoma biopsies and surgical specimens significantly differ from those routinely applied in breast carcinoma. The main variations with regard to the pattern of reactivity in HER2-expressing cells are as follows: the completeness of membrane staining is not a "conditio sine qua non" and the number of stained cells necessary to consider a case as positive is different. We must also take note of the much more frequent heterogeneity of HER2 positivity in gastric cancer compared with breast carcinoma and the less stringent correlation between HER2 amplification and protein overexpression that is observed in gastric carcinoma, where more than 20% of cases may carry HER2 amplification, although of low level, without HER2 expression. In these patients, in the ToGA trial, there was no apparent benefit from adding Trastuzumab to chemotherapy: for this reason the European Medicines Agency, while approving usage of Trastuzumab for metastatic adenocarcinoma treatment, indicated HER2 testing by immunohistochemistry as first evaluation assay, followed by fluorescence in situ hybridization in 2+ equivocal cases. HER2 testing in gastric carcinoma is a new field, opening several opportunities: for patients with gastric cancer, this is a new promising therapeutic option; for pathologists, strengthening our role in therapy selection and emphasizing our duty of providing accurate and reproducible HER2 testing results; for all interested in understanding the biology of gastric and GEJ cancer and in discovering new possible molecular therapy targets.