ER+, ErbB-1+, and/or ErbB-2+ primary breast cancer responded well to letrozole, but responses to tamoxifen were infrequent. This suggests that ErbB-1 and ErbB-2 signaling through ER is ligand-dependent and that the growth-promoting effects of these receptor tyrosine kinases on ER+ breast cancer can be inhibited by potent estrogen deprivation therapy.

BackgroundUnderstanding how tumor response is related to relapse risk would help clinicians make decisions about additional treatment options for patients who have received neoadjuvant endocrine treatment for estrogen receptor–positive (ER+) breast cancer.MethodsTumors from 228 postmenopausal women with confirmed ER+ stage 2 and 3 breast cancers in the P024 neoadjuvant endocrine therapy trial, which compared letrozole and tamoxifen for 4 months before surgery, were analyzed for posttreatment ER status, Ki67 proliferation index, histological grade, pathological tumor size, node status, and treatment response. Cox proportional hazards were used to identify factors associated with relapse-free survival (RFS) and breast cancer–specific survival (BCSS) in 158 women. A preoperative endocrine prognostic index (PEPI) for RFS was developed from these data and validated in an independent study of 203 postmenopausal women in the IMPACT trial, which compared treatment with anastrozole, tamoxifen, or the combination 3 months before surgery. Statistical tests were two-sided.ResultsMedian follow-up in P024 was 61.2 months. Patients with confirmed baseline ER+ clinical stage 2 and 3 tumors that were downstaged to stage 1 or 0 at surgery had 100% RFS (compared with higher stages, P < .001). Multivariable testing of posttreatment tumor characteristics revealed that pathological tumor size, node status, Ki67 level, and ER status were independently associated with both RFS and BCSS. The PEPI model based on these factors predicted RFS in the IMPACT trial (P = .002).ConclusionsBreast cancer patients with pathological stage 1 or 0 disease after neoadjuvant endocrine therapy and a low-risk biomarker profile in the surgical specimen (PEPI score 0) have an extremely low risk of relapse and are therefore unlikely to benefit from adjuvant chemotherapy.

IGF-IR-mediated signaling promotes survival, anchorage-independent growth, and oncogenic transformation, as well as tumor growth and metastasis formation in vivo. NVP-AEW541 is a pyrrolo[2,3-d]pyrimidine derivative small molecular weight kinase inhibitor of the IGF-IR, capable of distinguishing between the IGF-IR (IC50 = 0.086 microM) and the closely related InsR (IC50 = 2.3 microM) in cells. As expected for a specific IGF-IR kinase inhibitor, NVP-AEW541 abrogates IGF-I-mediated survival and colony formation in soft agar at concentrations that are consistent with inhibition of IGF-IR autophosphorylation. In vivo, this orally bioavailable compound inhibits IGF-IR signaling in tumor xenografts and significantly reduces the growth of IGF-IR-driven fibrosarcomas. Thus, NVP-AEW541 represents a class of selective, small molecule IGF-IR kinase inhibitors with proven in vivo antitumor activity and potential therapeutic application.

Purpose: The possible involvement of gender-dependent factors has been suggested in human non-small cell lung carcinomas (NSCLC), but their precise roles remain largely unclear. Therefore, we examined intratumoral estradiol concentrations in NSCLC to examine local actions of estrogens in NSCLC. Experimental Design: Fifty-nine frozen specimens of NSCLC were available for liquid chromatography/electrospray tandem mass spectrometry to study intratumoral estradiol concentrations. In addition, A549 NSCLC cells stably expressing estrogen receptor (ER) a (A549 + ERa) or ERh (A549 + ERh) were used in vitro studies. Results: Forty-three (73%) of 59 NSCLC showed higher concentration of estradiol in carcinoma tissues than the corresponding nonneoplastic lung tissues from the same patient, and intratumoral estradiol concentrations were significantly (P = 0.0002 and 2.2-fold) higher than the corresponding nonneoplastic lungs. The intratumoral concentration of estradiol was positively correlated with aromatase expression, tumor size, and Ki-67 status in ERa-or ERh-positive cases. In in vitro studies, estradiol significantly increased cell proliferation of A549 + ERa orA549 + ERh, which was significantly suppressed by selective ER modulators, tamoxifen or raloxifene. Both A549 + ERa and A549 + ERh cells expressed aromatase. The cell proliferation level in these cells was significantly increased under treatment with testosterone, and it was inhibited by addition of the aromatase inhibitor letrozole. Conclusions: These results suggest that estradiol is locally produced in NSCLC mainly by aromatase and plays an important role in the growth of ERa-or ERh-positive NSCLC. Therefore, use of selective ER modulators and/or aromatase inhibitors may be clinically effective in NSCLC that are positive for both ER and aromatase.