PurposeTo assess the prognostic and predictive value of circulating ESR1 mutation and its kinetics before and after progression on aromatase inhibitor (AI) treatment.Patients and methodsESR1 circulating D538G and Y537S/N/C mutations were retrospectively analyzed by digital droplet PCR after first-line AI failure in patients treated consecutively from 2010 to 2012 for hormone receptor-positive metastatic breast cancer. Progression-free survival (PFS) and overall survival (OS) were analyzed according to circulating mutational status and subsequent lines of treatment. The kinetics of ESR1 mutation before (3 and 6 months) and after (3 months) AI progression were determined in the available archive plasmas.ResultsCirculating ESR1 mutations were found at AI progression in 44/144 patients included (30.6%). Median follow-up from AI initiation was 40 months (range 4-94). The median OS was decreased in patients with circulating ESR1 mutation than in patients without mutation (15.5 versus 23.8 months, P=0.0006). The median PFS was also significantly decreased in patients with ESR1 mutation than in patients without mutation (5.9 vs 7 months, P=0.002). After AI failure, there was no difference in outcome for patients receiving chemotherapy (n = 58) versus non-AI endocrine therapy (n=51) in patients with and without ESR1 mutation. ESR1 circulating mutations were detectable in 75% of all cases before AI progression, whereas the kinetics 3 months after progression did not correlate with outcome.ConclusionESR1 circulating mutations are independent risk factors for poor outcome after AI failure, and are frequently detectable before clinical progression. Interventional studies based on ESR1 circulating status are warranted.

Background: Limited evidence exists on the impact of adding a taxane, using endocrine therapy and carrying a deleterious germline BRCA mutation on ovarian reserve measured by anti-müllerian hormone (AMH) levels of young breast cancer patients receiving (neo)adjuvant cyclophosphamide- and anthracycline-based chemotherapy. Methods: This is a biomarker analysis including young (≤ 40 years) early breast cancer patients with known germline BRCA mutational status and available prospectively collected frozen plasma samples before and after chemotherapy. Chemotherapy consisted of either six cycles of FEC (5 fluorouracil 500 mg/m 2 , epirubicin 100 mg/m 2 , cyclophosphamide 500 mg/m 2 ) or three cycles of FEC followed by three cycles of docetaxel (D, 100 mg/m 2 ). Endocrine therapy consisted of tamoxifen (±GnRH agonists). AMH levels at baseline, 1 and 3 years after diagnosis were compared according to type of chemotherapy (FEC only vs. FEC-D), use of endocrine therapy (yes vs. no) and deleterious germline BRCA mutations (mutated vs. negative). Results: Out of 148 included patients, 127 (86%) received D following FEC chemotherapy, 90 (61%) underwent endocrine therapy, and 35 (24%) had deleterious germline BRCA mutations. In the whole cohort, AMH levels drastically dropped 1 year after diagnosis ( p < 0.0001) with a slight but significant recovery at 3 years ( p < 0.0001). One year after diagnosis, patients treated with FEC only had higher median AMH levels than those who received FEC-D (0.22 vs. 0.04 μg/L, p = 0.0006); no difference was observed at 3 years (0.06 and 0.18 μg/L, p = 0.47). Patients under endocrine therapy had significantly higher AMH levels than those who did not receive this treatment 1 year after diagnosis (0.12 vs. 0.02 μg/L; p = 0.008), with no difference at 3 years (0.11 and 0.20 μg/L, p = 0.22). AMH levels were similar between BRCA -mutated and BRCA -negative patients at baseline (1.94 vs. 1.66 μg/L, p = 0.53), 1 year (0.09 vs. 0.06 μg/L, p = 0.39) and 3 years (0.25 vs. 0.16 μg/L; p = 0.43) after diagnosis. Conclusions: In breast cancer patients receiving FEC chemotherapy, adding D appeared to negatively impact on their ovarian reserve in the short-term; no further detrimental effect was observed for endocrine therapy use and presence of a deleterious germline BRCA mutation.

Background and Purpose The neuropeptide 26RFa and its cognate receptor GPR103 are involved in the control of food intake and bone mineralization. Here, we have tested, experimentally, the predicted ligand‐receptor interactions by site‐directed mutagenesis of GPR103 and designed point‐substituted 26RFa analogues. Experimental Approach Using the X‐ray structure of the β2‐adrenoceptor, a 3‐D molecular model of GPR103 has been built. The bioactive C‐terminal octapeptide 26RFa(19–26), KGGFSFRF‐NH2, was docked in this GPR103 model and the ligand‐receptor complex was submitted to energy minimization. Key Results In the most stable complex, the Phe‐Arg‐Phe‐NH2 part was oriented inside the receptor cavity, whereas the N‐terminal Lys residue remained outside. A strong intermolecular interaction was predicted between the Arg25 residue of 26RFa and the Gln125 residue located in the third transmembrane helix of GPR103. To confirm this interaction experimentally, we tested the ability of 26RFa and Arg‐modified 26RFa analogues to activate the wild‐type and the Q125A mutant receptors transiently expressed in CHO cells. 26RFa (10−6 M) enhanced [Ca2+]i in wild‐type GPR103‐transfected cells, but failed to increase [Ca2+]i in Q125A mutant receptor‐expressing cells. Moreover, asymmetric dimethylation of the side chain of arginine led to a 26RFa analogue, [ADMA25]26RFa(20–26), that was unable to activate the wild‐type GPR103, but antagonized 26RFa‐evoked [Ca2+]i increase. Conclusion and Implications Altogether, these data provide strong evidence for a functional interaction between the Arg25 residue of 26RFa and the Gln125 residue of GPR103 upon ligand‐receptor activation, which can be exploited for the rational design of potent GPR103 agonists and antagonists.