pan-HER Inhibitor Research Articles

Cutaneous genital complications of antiangiogenic agents

e14568 Background: Multikinase inhibitors targeting VEGFR, i.e. sorafenib and sunitinib are associated with various cutaneous side effects (1). Five cases of scrotal skin lesions were recently reported in male patients treated with sunitinib (2). Our observations of 8 patients presenting with genital inflammatory lesions during various anti-VEGFR therapies show that this side effect is linked to VEGFR blockade and not specifically to sunitinib and that it can also occur in women. Results: Six men and two women were seen for a genital eruption. They were treated with sorafenib (3 pts), sunitinib (5 pts), and a new pan-HER and VEGFR inhibitor (BMS 514, EVRI) (1 pt) for renal cell cancer (4 pts), hepatocellular carcinoma (2 pts), lung cancer (1 pt) and sarcoma (1 pt). Genital lesions occurred during the first six weeks of treatment. They appeared as a painful erythematous and squamous inguinal, intergluteal, and perianal rash rapidly involving all genital areas in 4 patients. Lesions became erosive in 3 cases. Four men presented more limited, pruriginous and lichenoid penile papules which were associated with a genital erythema for 3 of them. In one patient, penile inflammation resulted in a phimosis. One patient successively treated with sunitinib, sorafenib and once again with sunitinib experienced genital side effects with both agents. Patients taking sequential sunitinib treatment reported symptoms improvement during treatment interruptions and recurrences during the weeks on therapy. Microbiological samples were negative. Pathology of erythematous and squamous lesions showed a psoriasiform or a lichenoid aspect. Topical steroids were efficient for 5 patients but 3 patients had to interrupt anti-VEGF therapy because of their genital rash. Conclusions: Polymorphous genital inflammatory rash is a new skin side effect that can be associated with any cancer therapies targeting VEGFR in men and in women. Its frequency is unknown and probably underestimated because many patients might not report this side effect and its mechanism is still obscure. Physicians should be aware of this side effect and should inquire as to whether the patients have noticed such symptoms in order to avoid worsening thereof by symptomatic measures. No significant financial relationships to disclose.

HER receptor signaling confers resistance to the insulin-like growth factor-I receptor inhibitor, BMS-536924

We have reported previously the activity of the insulin-like growth factor-I (IGF-IR)/insulin receptor (InsR) inhibitor, BMS-554417, in breast and ovarian cancer cell lines. Further studies indicated treatment of OV202 ovarian cancer cells with BMS-554417 increased phosphorylation of HER-2. In addition, treatment with the pan-HER inhibitor, BMS-599626, resulted in increased phosphorylation of IGF-IR, suggesting a reciprocal cross-talk mechanism. In a panel of five ovarian cancer cell lines, simultaneous treatment with the IGF-IR/InsR inhibitor, BMS-536924 and BMS-599626, resulted in a synergistic antiproliferative effect. Furthermore, combination therapy decreased AKT and extracellular signal-regulated kinase activation and increased biochemical and nuclear morphologic changes consistent with apoptosis compared with either agent alone. In response to treatment with BMS-536924, increased expression and activation of various members of the HER family of receptors were seen in all five ovarian cancer cell lines, suggesting that inhibition of IGF-IR/InsR results in adaptive up-regulation of the HER pathway. Using MCF-7 breast cancer cell variants that overexpressed HER-1 or HER-2, we then tested the hypothesis that HER receptor expression is sufficient to confer resistance to IGF-IR-targeted therapy. In the presence of activating ligands epidermal growth factor or heregulin, respectively, MCF-7 cells expressing HER-1 or HER-2 were resistant to BMS-536924 as determined in a proliferation and clonogenic assay. These data suggested that simultaneous treatment with inhibitors of the IGF-I and HER family of receptors may be an effective strategy for clinical investigations of IGF-IR inhibitors in breast and ovarian cancer and that targeting HER-1 and HER-2 may overcome clinical resistance to IGF-IR inhibitors.

A Splice Variant of HER2 Corresponding to Herstatin Is Expressed in the Noncancerous Breast and in Breast Carcinomas

Herstatin (HST) is an alternatively spliced HER2 product with growth-inhibitory properties in experimental cancer systems. The role of HST in adult human tissues and disease remains unexplored. Here, we investigated HST expression at the mRNA and protein (immunohistochemistry [IHC]) level in parallel with parameters reflecting HER activation in 187 breast carcinomas and matched noncancerous breast tissues (NCBT). Noncancerous breast tissues demonstrated the highest HST/HER2 transcript ratios corresponding to a few positive epithelial and stromal cells by IHC. Although HST/HER2 transcript ratios in tumors were inversely associated with HER2 IHC grading (P = .0048 for HER2 IHC-1+ and P = .0006 for HER2 IHC-2+ vs HER2-negative tumors), relative HST expression within the same tumor/NCBT system remained constant. HST/HER2 ratios did not predict the presence of HST protein, which was found in 46 (25%) of 187 tumors. A subgroup of HER2 IHC-3+ tumors exhibited high HST/HER2 transcript ratios, strong HST protein positivity, and cytoplasmic phospho-Akt/PKB and p21CIP1/WAF1 localization. In conclusion, HST may act as a paracrine factor in the adult breast. Because HST is described as an endogenous pan-HER inhibitor, the presence of this protein in breast carcinomas may portent the inefficiency of exogenous efforts to block HER2 dimerization, whereas its absence may justify such interventions.

HER receptor signaling confers resistance to IGF-1R targeted therapy

14510 Background: Signaling through the insulin-like growth factor 1 receptor (IGF-1R) has been implicated in the resistance to a number of clinically relevant anti-cancer agents, including inhibitors of the HER family of receptors. Preliminary data suggests that co-inhibition of IGF and HER pathways may improve the efficacy of targeting these pathways individually. Methods: Five ovarian cancer cell line where treated with the IGF-1R inhibitor, BMS-536924 (924) and/or the panHER inhibitor, BMS-599626. Activity was assessed by proliferation and apoptotic assays. Protein expression/activation was assessed by western blotting. Stably transfected MCF-7 variants were generated to contain either the empty expression vector (M/-), EGFR/HER1 (M/H1) or HER2 (M/H2). MCF-7R4 cells (R4) are a clonal isolate of MCF-7 cells passaged in high concentration of the IGF-1R inhibitor, BMS-554417. The expression profile of R4 cells were compared to MCF-7 using Affymetrix GeneChip Human Genome U133 Plus 2.0 Arrays. Results: IGF-1R and HER receptor co-inhibition had synergistic anti- proliferative activity in all 5 ovarian cell lines investigated. The mechanism of this synergy was enhancement of apoptosis. Evidence of HER receptor activation was observed in all cell lines in response to IGF-1R inhibition. M/H1 and M/H2 became highly resistant to the effects of 924 in the presence of EGF and heregulin, respectively. R4 cells are cross-resistant to 924 and other IGF-1R inhibitors. Compared to MCF-7 cells, HER2 and HER3 are upregulated and overactivated in R4 cells. Additionally, R4 cells have altered expression of IGFBP-5, -6 and IRS-1, -2. Conclusions: Co-inhibition of IGF-1R and HER receptors leads to synergistic activity in all tested ovarian cancer cell lines, all of which exhibited evidence of crosstalk. Activated EGFR or HER2 appears sufficient for resistance to IGF-1R inhibition. As IGF-1R inhibition strategies enter the clinic, HER receptors status and consideration of co-inhibition will be important for their development. Several IGF-1 system related proteins, including IGFBP-5 and 6 may have utility in predicting response to IGF-1R targeted therapy. Supported by the ASCO Young Investigator Award, Mayo Clinic Breast SPORE (CA116201–01) and K12 program (CA090628–05). Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Expert Testimony Other Remuneration Bristol-Myers Squibb Bristol-Myers Squibb, Pfizer Oncology Bristol-Myers Squibb

Preliminary activity and safety results from a phase I clinical trial of PF-00299804, an irreversible pan-HER inhibitor, in patients (pts) with NSCLC

8027 Background: PF-00299804 (PF) is an orally bioavailable, potent, irreversible small molecule inhibitor of HER1, HER2, and HER4. HER1 overexpression/aberrant function is widely observed in NSCLC and HER1 mutations are implicated in mechanisms of tumorigenesis and are associated with sensitivity to EGFR inhibitors gefitinib (G) and erlotinib (E). Results in pts with refractory NSCLC enriched for HER gene amplification, HER1/HER2 mutation, or wild type (WT) KRAS, within the phase I study are reported. Methods: NSCLC pts (n=42) received PF 16 mg (n=1), 30 mg (n=2), 45 mg, the MTD (n=33) or 60 mg (n=6) QD either continuously or for 2 weeks of a 3- week cycle. NSCLC pts were included in both the dose-escalation phase and at MTD, when additional NSCLC pts with HER1 mutant or KRAS WT tumors were recruited. Results: 44 pts with NSCLC have been enrolled to date (29 evaluable for response). Baseline characteristics were: median age 57 yrs (range 26–77), prior EGFR inhibitors 94% (E n=21, G n=6, E + G n=3; cetuximab n=1), prior chemotherapy 79% (median no. of regimens 2; range 0–6), never smokers (48%), ex-smokers (45%) and current smokers (6%). Mutational status was known in part for 30 pts: HER1 mutant/WT: 23/7; KRAS WT/unknown: 17/13. The median duration of therapy was 2 mths (range 1- 6).23 pts received PF 45 mg QD for which the safety profile is as follows: G3: fatigue, DVT, nausea, acne, hypokalemia, diarrhea, hypoxia, and decreased appetite; G4: dyspnea, pulmonary embolism, and pain. The most frequently reported AEs (any grade) were diarrhea (78%) and rash (65%). Among 29 pts evaluable for tumor response, 2 PRs (RECIST) were noted and an additional 8 pts reported SD (clinical benefit rate 34%). Of the 2 PRs, one pt received PF 16 mg QD escalated to 30 mg QD and had previously received 6 lines of chemotherapy and G (6 months); the second received PF 45 mg QD, had previously received 3 lines of chemotherapy and E (4 months), and had a EGFR exon 20 insertion (D770delinsGI) mutation. Both PRs were durable (>200 days). Conclusions: PF-00299804 45 mg QD is well tolerated. Encouraging activity was seen in heavily pre-treated NSCLC pts, including 2 PRs after failure of prior treatment with reversible EGFR inhibitors. Phase II studies in refractory NSCLC pts are underway. Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Expert Testimony Other Remuneration Pfizer AstraZeneca, Boehringer Ingelheim, Pfizer, Roche Pfizer GlaxoSmithKline Pfizer Genzyme

CXCL12/CXCR4 Transactivates HER2 in Lipid Rafts of Prostate Cancer Cells and Promotes Growth of Metastatic Deposits in Bone

Chemokines and their receptors function in migration and homing of cells to target tissues. Recent evidence suggests that cancer cells use a chemokine receptor axis for metastasis formation at secondary sites. Previously, we showed that binding of the chemokine CXCL12 to its receptor CXCR4 mediated signaling events resulting in matrix metalloproteinase-9 expression in prostate cancer bone metastasis. A variety of methods, including lipid raft isolation, stable overexpression of CXCR4, cellular adhesion, invasion assays, and the severe combined immunodeficient-human bone tumor growth model were used. We found that (a) CXCR4 and HER2 coexist in lipid rafts of prostate cancer cells; (b) the CXCL12/CXCR4 axis results in transactivation of the HER2 receptor in lipid rafts of prostate cancer cells; (c) Src kinase mediates CXCL12/CXCR4 transactivation of HER2 in prostate cancer cells; (d) a pan-HER inhibitor desensitizes CXCR4-induced transactivation and subsequent matrix metalloproteinase-9 secretion and invasion; (e) lipid raft-disrupting agents inhibited raft-associated CXCL12/CXCR4 transactivation of the HER2 and cellular invasion; (f) overexpression of CXCR4 in prostate cancer cells leads to increased HER2 phosphorylation and migratory properties of prostate cancer cells; and (g) CXCR4 overexpression enhances bone tumor growth and osteolysis. These data suggest that lipid rafts on the cell membrane are the key site for CXCL12/CXCR4-induced HER2 receptor transactivation. This transactivation contributes to enhanced invasive signals and metastatic growth in the bone microenvironment.

126 INVITED New drug treatment for cancer in 2007 – real progress at last?

The epidermal growth factor receptor (EGFR), a member of the HER family of receptors, has become a well-established target for the treatment of patients with non-small cell lung cancer (NSCLC). Several EGFR-targeted agents produce objective responses in a minority of unselected patients, but a majority of those with EGFR-activating mutations; however, all responders eventually develop resistance. The modest activity of agents that target only EGFR may be due, in part, to the complexity and interdependency of HER family signaling. The interdependent signaling that occurs between EGFR and HER2 provides a rationale for the simultaneous inhibition of these receptors with reversible and irreversible inhibitors. Several agents with activity against both EGFR and HER2 are currently under development. Irreversible EGFR/HER2 tyrosine kinase inhibitors (TKIs) (e.g., BIBW 2992, HKI-272) and pan-HER TKIs (e.g., PF00299804) comprise a novel class of agents in clinical development that may prevent and overcome inherent and acquired resistance to first-generation reversible EGFR TKIs. Other agents in development include the monoclonal antibody pertuzumab, and XL-647, which inhibits EGFR and HER2, as well as multiple vascular endothelial growth factor receptor family members. Here we briefly review the currently available EGFR-targeted agents, discuss the rationale for extending inhibition to other HER family members, weigh the merits of irreversible HER family inhibition, and summarize preclinical and clinical data with EGFR/HER2 and pan-HER inhibitors under clinical development.

First-in-human study of the safety, tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) of PF-00299804, a small molecule irreversible panHER inhibitor in patients with advanced cancer

3599 Background: There are scientific rationale for inhibitors which provide combined and irreversible blockade of HER family members. PF-00299804 is an orally available, potent, irreversible small molecule inhibitor of the HER tyrosine kinases. Methods: The safety, tolerability, PK, PD, and efficacy of PF-00299804 administered orally once daily in 3-week cycles were assessed in patients with advanced solid tumors using an accelerated dose-escalation design. Safety assessments included adverse event (AE), laboratory, ECG, and LVEF assessments. PK parameters were determined after a single lead-in dose and on Day 14 by non-compartmental techniques. PD measures included assessment of HER-related signaling pathways via IHC analyses of serial skin and, in some patients, tumor biopsies. Serial 18F-FDG- PET/CT has been performed on a subset of patients with scans being classified according to modified EORTC criteria by a central reader. Results: 32 pts have been treated across 8 sequential dose levels ranging from 0.5 to 60 mg. The most common AEs were diarrhea, fatigue, nausea, and rash. 3/6 patients at 60 mg experienced a DLT [hand-foot syndrome (1), dehydration related to diarrhea(1), mucositis(1)]. Cmax and AUC of PF-00299804 increased with dose in an approximately proportional manner. Accumulation ranged from 3.3 to 6.8, suggesting a terminal t1/2>24 h. At the 30 mg dose level, mean Day 14 drug concentration was above the predicted efficacious concentration for tumor growth inhibition based on A431 xenograft model. Of 7 sets of PET data evaluated thus far, partial responses (PR) have been observed in 2 patients. A PR as assessed using RECIST criteria has been reported in 1 of 2 patients with advanced refractory NSCLC treated to date. Conclusions: Daily administration of PF-00299804 across many dose levels appears safe and tolerable. Diarrhea, fatigue, nausea, and rash are the most frequent AEs. Evaluation of 45 mg/d as the potential MTD is ongoing. Systemic exposures at doses = 30 mg exceed the threshold for efficacy as predicted from preclinical studies. Clinical and biological activity of PF-00299804 was observed including a PR in 1 of 2 patients with advanced refractory NSCLC. No significant financial relationships to disclose.

1451 ORAL The Pan-HER inhibitor BMS-599626: biological effects, pharmacokinetic profile, and early clinical evaluation of a phase I trial

1451 ORAL The Pan-HER inhibitor BMS-599626: biological effects, pharmacokinetic profile, and early clinical evaluation of a phase I trial

Phase I pharmacokinetic profile and early clinical evaluation of the PAN-HER inhibitor BMS-599626

3109 Background: BMS-599626 is an orally bioavailable inhibitor of HER1 (EGFR), HER2 (ErbB2) and to a lesser extent HER4. Methods: This is a phase I dose escalation study of BMS-599626 administered by daily oral dosing. Patients: ≥18 yrs with metastatic solid tumors, refractory to standard therapies and whose tumors expressed HER1 or HER2 by IHC (FISH for breast). A large translational ancillary study included skin biopsies (baseline and Day 8) and analysis of biomarkers of HER1 and HER2. Dosing was initiated at 100mg/d and escalated in subsequent cohorts based on a modified Fibonacci scheme. Data from a prior healthy volunteer study, which evaluated single dose PK in 18 subjects, 6 at each dose level (10mg, 30mg and 100mg) is also included. Results: Between May and November 2004, 13 patients have been enrolled; cohort level 5 has reached a dose level of 660 mg. Adverse events at least possibly related to BMS-599626 of 24 Nov 2004 include diarrhea (3), anorexia (1), dyspnea (1), sweating (1) and rash (2); all grades 1 or 2. All 3 patients at 480mg developed grade 1 skin-rash (not yet in database). The healthy volunteer study had one AE: transient grade 2 ALT elevation. Three out of 13 patients allowed fresh tumor sampling before and during treatment. Plasma pharmacokinetics of BMS-599626 for the 100 and 200mg dose were available at the time of abstract submission. For the 100mg dose, the Tmax ranged from 1 to 8h (median 4h), somewhat delayed compared to the healthy volunteer study (median 2 hr). Following a single 100mg dose, the geomean Cmax=62 ng/mL, mean AUC0-∞=1570 ng/mL hr, relatively low compared to the healthy volunteer study, which revealed 120 ng/mL and 2610 ng/mL hr respectively. PK on day 8 and day 29 revealed similar findings, with respective geomean values of Cmax =167 and 210 ng/mL and AUC0-∞=2340 and 2545 ng/mL hr, suggesting no significant accumulation in exposure over time. Terminal half life was about 17 hrs. Exposure increase with the 200 mg dose was linear from the 100 mg dose. Conclusions: BMS-599626 has been well tolerated, with mild target-related AEs. The maximum tolerated dose has not yet been reached. Additional clinical, pharmacological and translational data will be presented. Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Bristol-Myers Squibb Bristol-Myers Squibb Bristol-Myers Squibb Bristol-Myers Squibb

Targeting the HER-kinase axis in cancer

The human epidermal growth factor receptor (HER) family of receptor tyrosine kinases controls critical pathways involved in the differentiation, growth, division, and motility of normal epithelial cells. Most human solid tumors are of epithelial origin. The process of malignant transformation and progression in many cancers may depend on activation of ligands and receptors that function as part of the HER-kinase pathway. This signaling axis has earned increased attention because of the development of antibodies and small-molecule tyrosine kinase inhibitors that specifically target components of the HER-kinase axis for cancer therapy. This review focuses on the basic biology underlying HER-kinase pathway activation and the current state of development for agents that target this axis. In particular, the importance of pan-HER inhibitors is discussed.