Purpose At least 94 common single nucleotide polymorphisms (SNPs) are associated with breast cancer. The extent to which an SNP panel can refine risk in women who receive preventive therapy has not ...been directly assessed previously. Materials and Methods A risk score on the basis of 88 SNPs (SNP88) was investigated in a nested case-control study of women enrolled in the International Breast Intervention Study (IBIS-I) or the Royal Marsden study. A total of 359 women who developed cancer were matched to 636 controls by age, trial, follow-up time, and treatment arm. Genotyping was done using the OncoArray. Conditional logistic regression and matched concordance indices (mC) were used to measure the performance of SNP88 alone and with other breast cancer risk factors assessed using the Tyrer-Cuzick (TC) model. Results SNP88 was predictive of breast cancer risk overall (interquartile range odds ratio IQ-OR, 1.37; 95% CI, 1.14 to 1.66; mC, 0.55), but mainly for estrogen receptor-positive disease (IQ-OR, 1.44; 95% CI, 1.16 to 1.79; P for heterogeneity = .10) versus estrogen receptor-negative disease. However, the observed risk of SNP88 was only 46% (95% CI, 19% to 74%) of expected. No significant interaction was observed with treatment arm (placebo IQ-OR, 1.46; 95% CI, 1.13 to 1.87; tamoxifen IQ-OR, 1.25; 95% CI, 0.96 to 1.64; P for heterogeneity = .5). The predictive power was similar to the TC model (IQ-OR, 1.45; 95% CI, 1.21 to 1.73; mC, 0.55), but SNP88 was independent of TC (Spearman rank-order correlation, 0.012; P = .7), and when combined multiplicatively, a substantial improvement was seen (IQ-OR, 1.64; 95% CI, 1.36 to 1.97; mC, 0.60). Conclusion A polygenic risk score may be used to refine risk from the TC or similar models in women who are at an elevated risk of breast cancer and considering preventive therapy. Recalibration may be necessary for accurate risk assessment.
Tumor expression of the proliferation antigen Ki67 is widely used to assess the prognosis of cancer patients. A change in the expression of Ki67 after short-term exposure of patients to therapeutic ...agents is frequently used as a pharmacodynamic marker of efficacy, particularly among breast cancer patients before undergoing surgery. To determine the clinical significance of the level of tumor cell proliferation during endocrine therapy for breast cancer, we measured the expression of Ki67 in tumor biopsy samples taken before and after 2 weeks of presurgical treatment with anastrozole or tamoxifen or the combination of anastrozole plus tamoxifen in 158 patients with hormone receptor–positive primary disease. In a multivariable analysis, we found that higher Ki67 expression after 2 weeks of endocrine therapy was statistically significantly associated with lower recurrence-free survival (P = .004) whereas higher Ki67 expression at baseline was not. Larger baseline tumor size and lower estrogen receptor level after 2 weeks of treatment were also statistically significantly associated with poorer recurrence-free survival (P<.001 and P = .04, respectively). Our data indicate that measurements of tumor Ki67 level after short-term endocrine treatment may improve the prediction of recurrence-free survival by integrating the prognostic value of Ki67 level at baseline with changes in Ki67 level that are associated with treatment benefit.
Endocrine therapy resistance invariably develops in advanced estrogen receptor-positive (ER⁺) breast cancer, but the underlying mechanisms are largely unknown. We have identified C-terminal SRC ...kinase (CSK) as a critical node in a previously unappreciated negative feedback loop that limits the efficacy of current ER-targeted therapies. Estrogen directly drives CSK expression in ER⁺ breast cancer. At low CSK levels, as is the case in patients with ER⁺ breast cancer resistant to endocrine therapy and with the poorest outcomes, the p21 protein-activated kinase 2 (PAK2) becomes activated and drives estrogen-independent growth. PAK2 overexpression is also associated with endocrine therapy resistance and worse clinical outcome, and the combination of a PAK2 inhibitor with an ER antagonist synergistically suppressed breast tumor growth. Clinical approaches to endocrine therapy-resistant breast cancer must overcome the loss of this estrogen-induced negative feedback loop that normally constrains the growth of ER⁺ tumors.
To evaluate growth factor receptor cross talk with the estrogen receptor (ER) in paired clinical breast cancer specimens and in a xenograft model before tamoxifen and at tumor progression as a ...possible mechanism for tamoxifen resistance.
Specimen pairs from 39 patients were tissue arrayed and stained for ER, progesterone receptor (PgR), Bcl-2, c-ErbB2 (HER-2), and phosphorylated (p) p38 mitogen-activated protein kinase (MAPK), p-ERK1/2 MAPK, and p-Akt. Xenograft MCF-7 tumors before and after tamoxifen resistance were assessed for levels of p-p38.
Pretreatment, there were strong correlations between ER, PgR, and Bcl-2, and an inverse correlation between ER and HER-2. These correlations were lost in the tamoxifen- resistant tumors and replaced by strong correlations between ER and p-p38 and p-ERK. ER expression was lost in 17% of resistant tumors. Three (11%) of the 26 tumors originally negative for HER-2 became amplified and/or overexpressed at resistance. All ER-positive tumors that overexpressed HER-2 originally or at resistance expressed high levels of p-p38. In the pretreatment and tamoxifen-resistant specimens, there were strong correlations between p-p38 and p-ERK. In the tamoxifen-resistant xenograft tumors, like the clinical samples, there was a striking increase in p-p38.
The molecular pathways driving tumor growth can change as the tumor progresses. Crosstalk between ER, HER-2, p38, and ERK may contribute to tamoxifen resistance and may provide molecular targets to overcome this resistance.
In clinical practice, oestrogen receptor (ER) analysis is almost entirely by immunohistochemistry (IHC). ASCO/CAP recommends cut-offs of < 1% (negative) and 1-10% (low) cells positive. There is ...uncertainty whether patients with ER low tumours benefit from endocrine therapy. We aimed to assess IHC and mRNA cut-points for ER versus biological response of primary breast cancer to 2 weeks' aromatase inhibitor treatment as measured by change in Ki67.
Cases were selected from the aromatase inhibitor treatment group of POETIC. We selected the 15% with the poorest Ki67 response (PR, < 40% Ki67 suppression, n = 230) and a random 30% of the remainder categorised as intermediate (IR, 40-79% Ki67 suppression, n = 150) and good-responders (GR, ≥ 80% Ki67 suppression, n = 230) from HER2 - group. All HER2 + cases available were selected irrespective of their response category (n = 317). ER expression was measured by IHC and qPCR.
ER IHC was available from 515 HER2 - and 186 HER2 + tumours and ER qPCR from 367 HER2 - and 171 HER2 + tumours. Ninety-one percentage of patients with ER IHC < 10% were PRs with similar rates in HER2 - and HER2 + cases. At or above ER IHC 10% substantial numbers of patients showed IR or GR. Similar proportions of patients were defined by cut-points of ER IHC < 10% and ER mRNA < 5 units. In addition, loss of PgR expression altered ER anti-proliferation response with 92% of PgR - cases with ER IHC < 40% being PRs.
There was little responsiveness at IHC < 10% and no distinction between < 1% and 1-10% cells positive. Similar separation of PRs from IR/GRs was achieved by IHC and mRNA.
Ki67 assessed at diagnosis (Ki67
) is an important prognostic factor in primary oestrogen receptor-positive (ER +) breast cancer. Proportional change in Ki67 after 2 weeks (∆Ki67
) is associated with ...clinical benefit from endocrine therapies and residual Ki67 (Ki67
) with recurrence-free survival. The aim was to define the association between Ki67
and after aromatase inhibitor (AI) exposure ∆Ki67
and Ki67
with key prognostic and biologic factors utilising data from the POETIC study.
In POETIC 4480 postmenopausal patients with primary ER and/or PgR + breast cancer were randomised 2:1 to 2 weeks' presurgical AI (anastrozole or letrozole) or no presurgical treatment (control). Ki67 was measured centrally in core-cut biopsies taken prior to AI and in core-cuts or the excision biopsy at surgery. Relationships between the Ki67 and biologic factors were explored using linear regression.
Established associations of Ki67
with biologic factors including PgR status, tumour grade, tumour size, histological subtype, nodal status, and vascular invasion were confirmed in the HER2- subpopulation. In the HER2 + subpopulation only grade and tumour size were significantly associated with Ki67
. In control group Ki67
was 18% lower than Ki67
(p < 0.001) when Ki67
was measured in excision biopsies but not when measured in core-cuts. Median suppression by AIs (∆Ki67
) was 79.3% (IQR: -89.9 to -54.6) and 53.7% (IQR: -78.9 to -21.1) for HER2-negative and HER2-positive cases, respectively. Significantly less suppression occurred in PgR- vs PgR + and HER2 + vs HER2- tumours which remained apparent after adjustment for 2-week sample type.
The magnitude of this study allowed characterisation of relationships between Ki67
, ∆Ki67
and Ki67
with high degrees of confidence providing a reference source for other studies. Lower values of Ki67 occur when measured on excision biopsies and could lead to apparent but artefactual decreases in Ki67: this should be considered when either ∆Ki67
or Ki67
is used in routine clinical practice to aid treatment decisions or in clinical trials assessing new drug therapies.
Increased epidermal growth factor receptor (EGFR) expression may promote breast cancer resistance to endocrine therapy. We have therefore investigated whether neoadjuvant gefitinib, an EGFR ...inhibitor, might overcome biologic and clinical resistance to neoadjuvant anastrozole in a phase II placebo-controlled trial.
Postmenopausal women with stage I to IIIB hormone receptor-positive early breast cancer received anastrozole 1 mg daily for 16 weeks and were randomly assigned at a ratio of 2:5:5 to receive, in addition, gefitinib 250 mg/d orally for 16 weeks: placebo 1 tablet/d orally for 2 weeks and then gefitinib for 14 weeks or placebo for 16 weeks. The primary end point was biologic change in proliferation as measured by Ki67 at 2 and 16 weeks; the main secondary end point was overall objective response (OR).
Two hundred six women were randomly assigned. Mean changes in Ki67 with anastrozole and gefitinib versus anastrozole alone were -77.4% and -83.6%, respectively, between baseline and 16 weeks (geometric mean ratio = 1.37; 95% CI, 0.79 to 2.39; P = .26), -80.1% and -71.3% between baseline and 2 weeks (geometric mean ratio = 0.70; 95% CI, 0.39 to 1.25; P = .22) and -19.3% and -43% (geometric mean ratio = 1.42; 95% CI, 0.86 to 2.35; P = .16) between 2 and 16 weeks. ORs in the combination and anastrozole alone groups were 48% and 61% (estimated difference = -13.1%; 95% CI, -27.3% to 1.2%), respectively, with a nonsignificant trend against the combination (P = .08) and 48% versus 72% (estimated difference = -24.1%; 95% CI, -45.3% to -2.9%) in the progesterone-receptor-positive subgroup, which was significant (P = .03) and consistent with Ki67 changes. Common treatment-related adverse events included diarrhea, rash, alopecia, dry skin, and nausea. There was no evidence of a pharmacokinetic interaction.
Addition of gefitinib to neoadjuvant anastrozole had no additional clinical or biologic effect, failing to support our original hypothesis.
Very few studies have investigated whether the time elapsed between surgical resection and tissue fixation or the difference between core-cut and excision biopsies impact on immunohistochemically ...measured biomarkers including phosphorylated proteins in primary breast cancer. The aim of this study was to characterize the differences in immunoreactivity of common biomarkers that may occur (a) due to tissue handling at surgery and (b) between core-cuts and resected tumours.
Core-cuts taken from surgical breast cancer specimens immediately after resection (sample A) and after routine X-ray of the excised tumour (sample B) were formalin-fixed and paraffin-embedded and compared to the routinely fixed resection specimen (sample C). The variation in immunohistochemical expression of Ki67, oestrogen receptor (ER), progesterone receptor (PgR), human epidermal growth factor 2 (HER2), p-Akt and p-Erk were investigated.
Twenty-one tissue sets with adequate tumour were available. Median time between collection of core-cuts A and B was 30 minutes (range 20 to 80). None of the markers showed significant differences between samples A and B. Similarly, Ki67, ER, PgR and HER2 did not differ significantly between core-cuts and main resection specimen although there was a trend for lower resection values for ER (P=0.06). However, p-Akt and p-Erk1/2 were markedly lower in resections than core-cuts (median 27 vs 101 and 69 vs 193, respectively; both P<0.0001 two-sided). This difference was significantly greater in mastectomy than lumpectomy specimens for p-Erk1/2 (P=0.01).
The delay in fixation in core-cuts taken after post-operative X-ray of resection specimens has no significant impact on expression of Ki67, ER, PgR, HER2, p-Akt or p-Erk1/2. However extreme loss of phospho-staining can occur during routine fixation of resection specimens. These differences are likely attributable to suboptimal fixation and may have major repercussions for clinical research involving these markers.
To investigate the relationships between biomarker changes in breast cancer during neoadjuvant (preoperative) endocrine therapy.
The IMPACT trial compared the preoperative use of tamoxifen with ...anastrozole alone or in combination in postmenopausal women (n = 330) with primary breast cancer. Biomarkers were measured in tumor biopsy specimens taken at baseline, and after 2 and 12 weeks of treatment.
52 (93%) of 56, 46 (85%) of 54, and 37 (84%) of 44 patients in the anastrozole, tamoxifen, and combination groups, respectively. There was a significantly greater suppression of Ki67 in the anastrozole-treated group than in the tamoxifen- or combination-treated groups, which is parallel to the greater efficacy seen for anastrozole over these two treatments in the Arimidex, Tamoxifen, Alone or in Combination adjuvant trial. A positive relationship was noted between estrogen-receptor level and Ki67 suppression in all patients. Ki67 was reduced to a greater extent in progesterone receptor-positive tumors compared with progesterone receptor-negative tumors. HER-2-negative tumors tended to show a greater reduction in Ki67 compared with HER-2-positive tumors, but the difference was only significant in the tamoxifen group after 2 weeks, and in the anastrozole group after 12 weeks.
These results confirm the value of Ki67 as a molecular marker, and provide information regarding the relationships between treatment-induced changes in Ki67 and other important biomarkers. Studies such as this should help integrate agents targeted at growth factor signaling with endocrine agents in breast cancer.
The randomized, double-blinded Royal Marsden Tamoxifen Breast Cancer Prevention Trial in healthy high-risk women started in 1986 and is still blinded. Eligible participants (
= 2,471) were randomly ...assigned to tamoxifen (20 mg/d) or placebo for 8 years. Analysis in 2006 showed a 30% risk reduction of estrogen receptor (ER)-positive invasive breast cancer mostly in the posttreatment period. Biomarker analysis in this population may identify any subgroup-specific preventive effects tamoxifen. After a median follow-up of 18.4 years, 242 patients had developed invasive cancer, 134 on placebo and 108 on tamoxifen. From these, 180 tissue blocks were available and ER, progesterone receptor (PgR), Ki67, HER2, and EGFR were immunohistochemically analyzed. A 32% reduction in ER
and PgR
invasive cancers resulted after 8 years of treatment. Quantitative levels of ER and PgR were lower in the tamoxifen-treated group, significantly so for ER (
= 0.001). These lower ER levels were restricted to the posttreatment period (
= 0.018). Among the ER
group, there was a similar proportional decrease in PgR
and PgR
tumors by tamoxifen. The median levels of Ki67 were similar in both arms. The numbers of HER2-positive and EGFR-positive cancers were higher in the tamoxifen arm but not significantly so. In conclusion, the preventive effects of tamoxifen result in reduced ER-positive but not ER-negative tumors and reduced ER expression in the ER-positive cases largely confined to the posttreatment period. Overall reductions in PgR expression are explained by lower frequency of ER-positive cases. Impact on Ki67, HER2, and EGFR was modest.
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