Amivantamab plus Chemotherapy in NSCLC with EGFR Exon 20 Insertions.

BACKGROUND: Amivantamab has been approved for the treatment of patients with advanced non-small-cell lung cancer (NSCLC) with epidermal growth factor receptor (EGFR) exon 20 insertions who have had disease progression during or after platinum-based chemotherapy. Phase 1 data showed the safety and antitumor activity of amivantamab plus carboplatin-pemetrexed (chemotherapy). Additional data on this combination therapy are needed. METHODS: In this phase 3, international, randomized trial, we assigned in a 1:1 ratio patients with advanced NSCLC with EGFR exon 20 insertions who had not received previous systemic therapy to receive intravenous amivantamab plus chemotherapy (amivantamab-chemotherapy) or chemotherapy alone. The primary outcome was progression-free survival according to blinded independent central review. Patients in the chemotherapy group who had disease progression were allowed to cross over to receive amivantamab monotherapy. RESULTS: A total of 308 patients underwent randomization (153 to receive amivantamab-chemotherapy and 155 to receive chemotherapy alone). Progression-free survival was significantly longer in the amivantamab-chemotherapy group than in the chemotherapy group (median, 11.4 months and 6.7 months, respectively; hazard ratio for disease progression or death, 0.40; 95% confidence interval [CI], 0.30 to 0.53; P<0.001). At 18 months, progression-free survival was reported in 31% of the patients in the amivantamab-chemotherapy group and in 3% in the chemotherapy group; a complete or partial response at data cutoff was reported in 73% and 47%, respectively (rate ratio, 1.50; 95% CI, 1.32 to 1.68; P<0.001). In the interim overall survival analysis (33% maturity), the hazard ratio for death for amivantamab-chemotherapy as compared with chemotherapy was 0.67 (95% CI, 0.42 to 1.09; P = 0.11). The predominant adverse events associated with amivantamab-chemotherapy were reversible hematologic and EGFR-related toxic effects; 7% of patients discontinued amivantamab owing to adverse reactions. CONCLUSIONS: The use of amivantamab-chemotherapy resulted in superior efficacy as compared with chemotherapy alone as first-line treatment of patients with advanced NSCLC with EGFR exon 20 insertions. (Funded by Janssen Research and Development; PAPILLON ClinicalTrials.gov number, NCT04538664.).

Clinical impact of ibrutinib plus R-CHOP in untreated DLBCL coexpressing BCL2 and MYC in the phase 3 PHOENIX trial.

Diffuse large B-cell lymphoma (DLBCL), with high coexpression of BCL2 and MYC proteins (DE lymphoma), is considered an adverse prognostic indicator associated mostly with non-germinal center B-cell-like (non-GCB) DLBCL. BCL2/MYC overexpression is associated with B-cell receptor (BCR) pathway activation; consequently, DE DLBCL may be sensitive to BCR inhibitors. We assessed whether high BCL2/MYC coexpression by RNA sequencing could identify a patient subset responsive to ibrutinib using baseline biopsies from the PHOENIX trial, which evaluated the addition of ibrutinib to rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) in untreated non-GCB DLBCL. BCL2/MYC RNA expression was correlated with lower event-free survival (EFS) and overall survival (OS) using Kaplan-Meier estimates with Cox regression and log-rank testing. In total, 234 of 766 (30.5%) patients had high BCL2/MYC coexpression: 123 of 386 (31.9%) received ibrutinib plus R-CHOP and 111 of 380 (29.2%) received R-CHOP. EFS was superior with ibrutinib plus R-CHOP compared with R-CHOP alone in patients with high BCL2/MYC coexpression, but there was no significant impact on OS. However, EFS and OS showed clinically meaningful improvement with ibrutinib plus R-CHOP over R-CHOP alone in patients aged <60 years with high BCL2/MYC coexpression. We observed a significant association between high BCL2/MYC coexpression and activated B-cell-like and MYD88L265P/CD79B-mutated subtypes of DLBCL. Consequently, high BCL2/MYC coexpression identified a subset of non-GCB DLBCL that may be preferentially responsive to ibrutinib and warrants further investigation. This trial was registered at www.clinicaltrials.gov as #NCT01855750.

Effects of food and race on the pharmacokinetics of lazertinib in healthy subjects and patients with EGFR mutation-positive advanced non-small cell lung cancer.

OBJECTIVES: Lazertinib is a potent, irreversible, brain-penetrant, mutant-selective, and wild type-sparing third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor indicated for advanced non-small cell lung cancer (NSCLC). The study aimed to evaluate the effects of food and race on the pharmacokinetics (PK) of lazertinib from a healthy volunteer trial and PK data from NSCLC patients with EGFR mutation. MATERIALS AND METHODS: An open-label, single-dose, two-period, single-sequence crossover study was conducted in healthy subjects with two race groups (non-Asian and Asian). Subjects orally received a single dose of lazertinib 240 mg in fasted and fed state (high-fat meal) in each period separated by a 21-day washout. An open-label, multicenter, phase 1/2 study was conducted in Asian and non-Asian patients with NSCLC. Patients were given oral lazertinib 20-320 mg once daily in fasted state continuously in 21-day cycles. PK parameters were evaluated using non-compartmental analysis. RESULTS: A total of 24 healthy subjects (12 non-Asians and 12 Asians) and 52 NSCLC patients (22 non-Asians and 30 Asians) were evaluated. The change in the overall systemic exposure of lazertinib at fed state was less than 15%. Non-Asians showed 58-76% of the systemic exposure than Asians in healthy subjects. In contrast, there were no significant differences in systemic exposure by race both after single and multiple doses among NSCLC patients. CONCLUSION: Lazertinib can be taken with or without food considering the comparable systemic exposures related to food. Although effect of race was not consistent across studies, there was no evidence for dose adjustment based on race.

MARIPOSA: phase 3 study of first-line amivantamab + lazertinib versus osimertinib in EGFR-mutant non-small-cell lung cancer.

Third-generation EGFR tyrosine kinase inhibitors (TKIs), such as osimertinib, have demonstrated efficacy in patients with EGFR-mutant non-small-cell lung cancer; however, almost all patients will eventually relapse. Amivantamab is an EGFR-MET bispecific antibody with immune cell-directing activity that targets activating and resistance EGFR mutations and MET mutations and amplifications. In the ongoing CHRYSALIS study (NCT02609776), amivantamab in combination with lazertinib, a potent, brain-penetrant third-generation EGFR TKI, demonstrated antitumor activity in the treatment-naive and osimertinib-relapsed setting. Here the authors present the methodology for the MARIPOSA study (NCT04487080), a phase 3, multicenter, randomized study designed to compare the efficacy and safety of amivantamab and lazertinib combination therapy versus single-agent osimertinib as first-line treatment for EGFR-mutant non-small-cell lung cancer.

Plain language summary Osimertinib is the standard-of-care treatment for patients with non-small-cell lung cancer caused by mutations in the EGFR. However, patients will eventually see their disease return because their tumors will develop new mutations that are resistant to osimertinib treatment. Amivantamab is a new antibody treatment that blocks the EGFR and another receptor called the MET receptor, to stop the growth of lung tumor cells. In an ongoing clinical trial, called the CHRYSALIS study, when amivantamab was given with lazertinib (another drug that blocks the EGFR), lung tumors shrank in patients whose lung cancer had not been previously treated. A new clinical trial called the MARIPOSA study (NCT04487080) aims to compare the antitumor activity and safety of the amivantamab + lazertinib combination versus osimertinib alone in patients with EGFR-mutant non-small-cell lung cancer who have not received treatment for their lung cancer. Trial registration number: NCT04487080 (ClinicalTrials.gov).

Comparison of immunohistochemistry and gene expression profiling subtyping for diffuse large B-cell lymphoma in the phase III clinical trial of R-CHOP ± ibrutinib.

We assessed the concordance between immunohistochemistry (IHC) and gene expression profiling (GEP) for determining diffuse large B-cell lymphoma (DLBCL) cell of origin (COO) in the phase III PHOENIX trial of rituximab plus cyclophosphamide, doxorubicin, vincristine and prednisone (R-CHOP) with or without ibrutinib. Among 910 of 1114 screened patients with non-germinal centre B cell-like (non-GCB) DLBCL by IHC, the concordance with GEP for non-GCB calls was 82·7%, with 691 (75·9%) identified as activated B cell-like (ABC), and 62 (6·8%) as unclassified. Among 746 of 837 enrolled patients with verified non-GCB DLBCL by IHC, the concordance with GEP was 82·8%, with 567 (76·0%) identified as ABC and 51 (6·8%) unclassified; survival outcomes were similar regardless of COO or treatment, whereas among patients with ABC DLBCL aged <60 years, the overall and event-free survival were substantially better with ibrutinib versus placebo plus R-CHOP [hazard ratio (HR) 0·365, 95% confidence interval (CI) 0·147-0·909, P = 0·0305; HR 0·561, 95% CI 0·326-0·967, P = 0·0348, respectively]. IHC and GEP showed high concordance and consistent survival outcomes among tested patients, indicating centralised IHC may be used to enrich populations for response to ibrutinib plus R-CHOP.

Randomized Phase III Trial of Ibrutinib and Rituximab Plus Cyclophosphamide, Doxorubicin, Vincristine, and Prednisone in Non-Germinal Center B-Cell Diffuse Large B-Cell Lymphoma.

PURPOSE: Ibrutinib has shown activity in non-germinal center B-cell diffuse large B-cell lymphoma (DLBCL). This double-blind phase III study evaluated ibrutinib and rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) in untreated non-germinal center B-cell DLBCL. PATIENTS AND METHODS: Patients were randomly assigned at a one-to-one ratio to ibrutinib (560 mg per day orally) plus R-CHOP or placebo plus R-CHOP. The primary end point was event-free survival (EFS) in the intent-to-treat (ITT) population and the activated B-cell (ABC) DLBCL subgroup. Secondary end points included progression-free survival (PFS), overall survival (OS), and safety. RESULTS: A total of 838 patients were randomly assigned to ibrutinib plus R-CHOP (n = 419) or placebo plus R-CHOP (n = 419). Median age was 62.0 years; 75.9% of evaluable patients had ABC subtype disease, and baseline characteristics were balanced. Ibrutinib plus R-CHOP did not improve EFS in the ITT (hazard ratio [HR], 0.934) or ABC (HR, 0.949) population. A preplanned analysis showed a significant interaction between treatment and age. In patients age younger than 60 years, ibrutinib plus R-CHOP improved EFS (HR, 0.579), PFS (HR, 0.556), and OS (HR, 0.330) and slightly increased serious adverse events (35.7% v 28.6%), but the proportion of patients receiving at least six cycles of R-CHOP was similar between treatment arms (92.9% v 93.0%). In patients age 60 years or older, ibrutinib plus R-CHOP worsened EFS, PFS, and OS, increased serious adverse events (63.4% v 38.2%), and decreased the proportion of patients receiving at least six cycles of R-CHOP (73.7% v 88.8%). CONCLUSION: The study did not meet its primary end point in the ITT or ABC population. However, in patients age younger than 60 years, ibrutinib plus R-CHOP improved EFS, PFS, and OS with manageable safety. In patients age 60 years or older, ibrutinib plus R-CHOP was associated with increased toxicity, leading to compromised R-CHOP administration and worse outcomes. Further investigation is warranted.

Effect of FAK inhibitor VS-6063 (defactinib) on docetaxel efficacy in prostate cancer.

BACKGROUND: Docetaxel, the standard chemotherapy for metastatic castration-resistant prostate cancer (CRPC) also enhances the survival of patients with metastatic castration-sensitive prostate cancer (CSPC) when combined with androgen-deprivation therapy. Focal Adhesion Kinase (FAK) activation is a mediator of docetaxel resistance in prostate cancer cells. The aim of this study was to investigate the effect of the second generation FAK inhibitor VS-6063 on docetaxel efficacy in pre-clinical CRPC and CSPC models. METHODS: Docetaxel-resistant CRPC cells, mice with PC3 xenografts, and ex vivo cultures of patient-derived primary prostate tumors were treated with VS-6063 and/or docetaxel, or vehicle control. Cell counting, immunoblotting, and immunohistochemistry techniques were used to evaluate the treatment effects. RESULTS: Docetaxel and VS-6063 co-treatment caused a greater decrease in the viability of docetaxel-resistant CRPC cells, and a greater inhibition in PC3 xenograft growth compared to either monotherapy. FAK expression in human primary prostate cancer was positively associated with advanced tumor stage. Patient-derived prostate tumor explants cultured with both docetaxel and VS-6063 displayed a higher percentage of apoptosis in cancer cells, than monotherapy treatment. CONCLUSIONS: Our findings suggest that co-administration of the FAK inhibitor, VS-6063, with docetaxel represents a potential therapeutic strategy to overcome docetaxel resistance in prostate cancer.

Combined Pan-HER and ALK/ROS1/MET Inhibition with Dacomitinib and Crizotinib in Advanced Non-Small Cell Lung Cancer: Results of a Phase I Study.

INTRODUCTION: This phase I study investigated the activity of the irreversible pan-human epidermal growth factor receptor inhibitor dacomitinib in combination with the mesenchymal-epithelial transition factor/anaplastic lymphoma kinase/ROS proto-oncogene 1, receptor tyrosine kinase inhibitor crizotinib in advanced non-small cell lung cancer. METHODS: Patients with progression after at least one line of chemotherapy or targeted therapy received dacomitinib once daily and crizotinib once daily or twice daily, with doses escalated until intolerable toxicity; the expansion cohorts received the maximum tolerated dose of the combination. The primary objective was to define the recommended phase II dose; secondary objectives included assessment of safety and activity of the combination in epidermal growth factor receptor inhibitor-resistant patients and correlation with tumor biomarkers. RESULTS: Seventy patients were treated in the dose-escalation (n = 33) and expansion phases (n = 37), with the maximum tolerated dose defined as dacomitinib, 30 mg once daily, plus crizotinib, 200 mg twice daily. Grade 3 or 4 treatment-related adverse events were reported in 43% of patients: the most common were diarrhea (16%), rash (7%), and fatigue (6%). There were 16 deaths; none were considered treatment related. One patient (1%) had a partial response; 46% had stable disease. Most of the tumor samples analyzed had activating epidermal growth factor receptor gene (EGFR) mutations (18 of 20 [90%]); 50% (10 of 20) had a concurrent resistance mutation. Only one sample showed MMNG HOS Transforming gene (MET) amplification (the patient had progressive disease), whereas 59% (13 of 22) and 47% (14 of 30) had high levels of expression of epidermal growth factor receptor and mesenchymal-epithelial transition factor on the basis of H-scores, respectively. There was no apparent association between biomarker expression and antitumor activity. CONCLUSION: The combination of dacomitinib and crizotinib showed limited antitumor activity in patients with advanced non-small cell lung cancer and was associated with substantial toxicity.

A phase I study of VS-6063, a second-generation focal adhesion kinase inhibitor, in patients with advanced solid tumors.

OBJECTIVE: VS-6063 (also known as defactinib or PF-04554878) is a second-generation inhibitor of focal adhesion kinase (FAK) and proline-rich tyrosine kinase-2 (Pyk2). This phase I dose-escalation study was conducted in patients with advanced solid malignancies. METHODS: Using a traditional 3 + 3 design, VS-6063 was administered orally twice daily (b.i.d.) in 21-day cycles to cohorts of three to six patients. In cycle 1, a lead-in dose was administered to assess single-dose pharmacokinetics; steady-state pharmacokinetics was assessed after 15 days of continuous dosing. Dose escalation was performed in the fasted state, and repeated in two additional cohorts in the fed state. RESULTS: Forty-six patients were treated across nine dose levels (12.5-750 mg b.i.d.). Dose-limiting toxicities, comprising headache (n = 1), fatigue (n = 1) and unconjugated hyperbilirubinemia (n = 3), occurred at the 300- or 425-mg b.i.d. dose level and were reversible. Frequent adverse events included nausea (37 %), fatigue (33 %), vomiting (28 %), diarrhea (22 %) and headache (22 %). A maximum-tolerated dose was not defined. Dose escalation was stopped at the 750-mg b.i.d. dose due to decreased serum exposure in the 500- and 750-mg versus 300- and 425-mg groups. Food delayed the time to peak serum concentration without affecting serum drug exposure. No radiographic responses were reported. Disease stabilization at ~12 weeks occurred in six of 37 (16 %) patients receiving doses ≥100 mg b.i.d. CONCLUSIONS: VS-6063 has an acceptable safety profile. Treatment-related adverse events were mild to moderate, and reversible. The recommended phase II fasting dose of VS-6063 is 425 mg b.i.d.

Clinical Experience With Crizotinib in Patients With Advanced ALK-Rearranged Non-Small-Cell Lung Cancer and Brain Metastases.

PURPOSE: Crizotinib is an oral kinase inhibitor approved for the treatment of ALK-rearranged non-small-cell lung cancer (NSCLC). The clinical benefits of crizotinib in patients with brain metastases have not been previously studied. PATIENTS AND METHODS: Patients with advanced ALK-rearranged NSCLC enrolled onto clinical trial PROFILE 1005 or 1007 (randomly assigned to crizotinib) were included in this retrospective analysis. Patients with asymptomatic brain metastases (nontarget or target lesions) were allowed to enroll. Tumor assessments were evaluated every 6 weeks using RECIST (version 1.1). RESULTS: At baseline, 31% of patients (275 of 888) had asymptomatic brain metastases; 109 had received no prior and 166 had received prior brain radiotherapy as treatment. Among patients with previously untreated asymptomatic brain metastases, the systemic disease control rate (DCR) at 12 weeks was 63% (95% CI, 54% to 72%), the intracranial DCR was 56% (95% CI, 46% to 66%), and the median intracranial time to progression (TTP) was 7 months (95% CI, 6.7 to 16.4). Among patients with previously treated brain metastases, the systemic DCR was 65% (95% CI, 57% to 72%), the intracranial DCR was 62% (95% CI, 54% to 70%), and the median intracranial TTP was 13.2 months (95% CI, 9.9 to not reached). Patients with systemic disease control were also likely to experience intracranial disease control at 12 weeks (correlation coefficient, 0.7652; P < .001). Among patients without baseline brain metastases who developed progressive disease (n = 253) after initiation of crizotinib, 20% were diagnosed with brain metastases. CONCLUSION: Crizotinib was associated with systemic and intracranial disease control in patients with ALK-rearranged NSCLC who were ALK inhibitor naive and had brain metastases. However, progression of preexisting or development of new intracranial lesions while receiving therapy was a common manifestation of acquired resistance to crizotinib.

Crizotinib in ROS1-rearranged non-small-cell lung cancer.

BACKGROUND: Chromosomal rearrangements of the gene encoding ROS1 proto-oncogene receptor tyrosine kinase (ROS1) define a distinct molecular subgroup of non-small-cell lung cancers (NSCLCs) that may be susceptible to therapeutic ROS1 kinase inhibition. Crizotinib is a small-molecule tyrosine kinase inhibitor of anaplastic lymphoma kinase (ALK), ROS1, and another proto-oncogene receptor tyrosine kinase, MET. METHODS: We enrolled 50 patients with advanced NSCLC who tested positive for ROS1 rearrangement in an expansion cohort of the phase 1 study of crizotinib. Patients were treated with crizotinib at the standard oral dose of 250 mg twice daily and assessed for safety, pharmacokinetics, and response to therapy. ROS1 fusion partners were identified with the use of next-generation sequencing or reverse-transcriptase-polymerase-chain-reaction assays. RESULTS: The objective response rate was 72% (95% confidence interval [CI], 58 to 84), with 3 complete responses and 33 partial responses. The median duration of response was 17.6 months (95% CI, 14.5 to not reached). Median progression-free survival was 19.2 months (95% CI, 14.4 to not reached), with 25 patients (50%) still in follow-up for progression. Among 30 tumors that were tested, we identified 7 ROS1 fusion partners: 5 known and 2 novel partner genes. No correlation was observed between the type of ROS1 rearrangement and the clinical response to crizotinib. The safety profile of crizotinib was similar to that seen in patients with ALK-rearranged NSCLC. CONCLUSIONS: In this study, crizotinib showed marked antitumor activity in patients with advanced ROS1-rearranged NSCLC. ROS1 rearrangement defines a second molecular subgroup of NSCLC for which crizotinib is highly active. (Funded by Pfizer and others; ClinicalTrials.gov number, NCT00585195.).

Safety, pharmacokinetic, and pharmacodynamic phase I dose-escalation trial of PF-00562271, an inhibitor of focal adhesion kinase, in advanced solid tumors.

PURPOSE: PF-00562271 is a novel inhibitor of focal adhesion kinase (FAK). The objectives of this study were to identify the recommended phase II dose (RP2D) and assess safety and tolerability, pharmacokinetics (PK), pharmacodynamics (PD), and antitumor activity of PF-00562271. PATIENTS AND METHODS: Part 1 was a dose escalation without and with food. Part 2 enrolled specific tumor types in an expansion at the RP2D and also assessed the effect of PF-00562271 on single-dose midazolam PK in a subgroup of patients. RESULTS: Ninety-nine patients (median age, 60 years; 98% with Eastern Cooperative Oncology Group performance status of 0 or 1) were treated in 12 fasting and three fed cohorts. The 125-mg twice-per-day fed dose was deemed the maximum-tolerated dose (MTD) and RP2D. Grade 3 dose-limiting toxicities included headache, nausea/vomiting, dehydration, and edema. Nausea was the most frequently observed toxicity (60% of patients, all grades 1 or 2 at RP2D). PF-00562271 exposure increased with increasing dose; serum concentration-time profiles showed characteristic nonlinear disposition. Steady-state exposures were reached within 1 week. On coadministration, geometric mean values of midazolam maximal observed serum concentration and area under the serum concentration-time curve increased by 60% and more than two-fold, respectively. Of 14 patients evaluable by [(18)F]fluorodeoxyglucose positron emission tomography in the expansion cohorts, seven metabolic responses were observed. With conventional imaging, 31 patients had stable disease at first restaging scans, and 15 of these remained stable for six or more cycles. CONCLUSION: The MTD and RP2D of PF-00562271 is 125 mg twice per day with food. PF-00562271 displayed time- and dose-dependent nonlinear PK and is likely a potent CYP 3A inhibitor. This first-in-class study supports further investigation of FAK as a promising therapeutic target.

Anaplastic lymphoma kinase inhibition in non-small-cell lung cancer.

BACKGROUND: Oncogenic fusion genes consisting of EML4 and anaplastic lymphoma kinase (ALK) are present in a subgroup of non-small-cell lung cancers, representing 2 to 7% of such tumors. We explored the therapeutic efficacy of inhibiting ALK in such tumors in an early-phase clinical trial of crizotinib (PF-02341066), an orally available small-molecule inhibitor of the ALK tyrosine kinase. METHODS: After screening tumor samples from approximately 1500 patients with non-small-cell lung cancer for the presence of ALK rearrangements, we identified 82 patients with advanced ALK-positive disease who were eligible for the clinical trial. Most of the patients had received previous treatment. These patients were enrolled in an expanded cohort study instituted after phase 1 dose escalation had established a recommended crizotinib dose of 250 mg twice daily in 28-day cycles. Patients were assessed for adverse events and response to therapy. RESULTS: Patients with ALK rearrangements tended to be younger than those without the rearrangements, and most of the patients had little or no exposure to tobacco and had adenocarcinomas. At a mean treatment duration of 6.4 months, the overall response rate was 57% (47 of 82 patients, with 46 confirmed partial responses and 1 confirmed complete response); 27 patients (33%) had stable disease. A total of 63 of 82 patients (77%) were continuing to receive crizotinib at the time of data cutoff, and the estimated probability of 6-month progression-free survival was 72%, with no median for the study reached. The drug resulted in grade 1 or 2 (mild) gastrointestinal side effects. CONCLUSIONS: The inhibition of ALK in lung tumors with the ALK rearrangement resulted in tumor shrinkage or stable disease in most patients. (Funded by Pfizer and others; ClinicalTrials.gov number, NCT00585195.).

Analyses of resected human brain metastases of breast cancer reveal the association between up-regulation of hexokinase 2 and poor prognosis.

Brain metastases of breast cancer seem to be increasingin incidence as systemic therapy improves. Metastatic disease in the brain is associated with high morbidity and mortality. We present the first gene expression analysis of laser-captured epithelial cells from resected human brain metastases of breast cancer compared with unlinked primary breast tumors. The tumors were matched for histology, tumor-node-metastasis stage, and hormone receptor status. Most differentially expressed genes were down-regulated in the brain metastases, which included, surprisingly, many genes associated with metastasis. Quantitative real-time PCR analysis confirmed statistically significant differences or strong trends in the expression of six genes: BMP1, PEDF, LAMgamma3, SIAH, STHMN3, and TSPD2. Hexokinase 2 (HK2) was also of interest because of its increased expression in brain metastases. HK2 is important in glucose metabolism and apoptosis. In agreement with our microarray results, HK2 levels (both mRNA and protein) were elevated in a brain metastatic derivative (231-BR) of the human breast carcinoma cell line MDA-MB-231 relative to the parental cell line (231-P) in vitro. Knockdown of HK2 expression in 231-BR cells using short hairpin RNA reduced cell proliferation when cultures were maintained in glucose-limiting conditions. Finally, HK2 expression was analyzed in a cohort of 123 resected brain metastases of breast cancer. High HK2 expression was significantly associated with poor patient survival after craniotomy (P = 0.028). The data suggest that HK2 overexpression is associated with metastasis to the brain in breast cancer and it may be a therapeutic target.

The role of metastasis suppressor genes in metastatic dormancy.

Metastasis suppressor genes (MSGs) are defined by their ability to inhibit overt metastasis in a secondary organ without affecting tumor growth at the primary site. Over 20 MSGs have been confirmed in vivo. This class of genes is only unified by their capacity to suppress metastasis, as they encode for proteins with a wide range of biochemical activities that are components of a variety of signaling pathways. In addition, metastasis suppressors impinge upon different stages of the metastatic cascade to manifest their suppressive effects. The MSGs KISS1, KAI1, MKK4/7 and Nm23-H1 promote tumor dormancy at the metastatic site, since tumor cells with induced expression of these MSGs disseminate, but do not form overt metastases in the secondary organ throughout the duration of a metastasis assay. Evidence suggests that KISS1 triggers dormancy in solitary, metastatic tumor cells by causing growth arrest of solitary cells at the secondary site. KAI1 induces growth arrest prior to extravasation by binding a vascular endothelial cell surface marker. MKK4, MKK7 and Nm23-H1 appear to promote dormancy of micrometastatic colonies, after disseminated tumor cells have undergone several rounds of proliferation. Other MSGs may also function in tumor dormancy, but so far their role has not been fully elucidated. Therapeutic approaches that either mimic the effects of MSGs or re-establish MSG expression in metastatic lesions may hold promise for the establishment or maintenance of dormancy.