Adjuvant Palbociclib for Early Breast Cancer: The PALLAS Trial Results (ABCSG-42/AFT-05/BIG-14-03)

PURPOSE

Palbociclib is a cyclin-dependent kinase 4 and 6 inhibitor approved for advanced breast cancer. In the adjuvant setting, the potential value of adding palbociclib to endocrine therapy for hormone receptor-positive breast cancer has not been confirmed.

PATIENTS AND METHODS

In the prospective, randomized, phase III PALLAS trial, patients with hormone receptor-positive, human epidermal growth factor receptor 2-negative early breast cancer were randomly assigned to receive 2 years of palbociclib (125 mg orally once daily, days 1-21 of a 28-day cycle) with adjuvant endocrine therapy or adjuvant endocrine therapy alone (for at least 5 years). The primary end point of the study was invasive disease-free survival (iDFS); secondary end points were invasive breast cancer-free survival, distant recurrence-free survival, locoregional cancer-free survival, and overall survival.

RESULTS

Among 5,796 patients enrolled at 406 centers in 21 countries worldwide over 3 years, 5,761 were included in the intention-to-treat population. At the final protocol-defined analysis, at a median follow-up of 31 months, iDFS events occurred in 253 of 2,884 (8.8%) patients who received palbociclib plus endocrine therapy and in 263 of 2,877 (9.1%) patients who received endocrine therapy alone, with similar results between the two treatment groups (iDFS at 4 years: 84.2% v 84.5%; hazard ratio, 0.96; CI, 0.81 to 1.14; P = .65). No significant differences were observed for secondary time-to-event end points, and subgroup analyses did not show any differences by subgroup. There were no new safety signals for palbociclib in this trial.

CONCLUSION

At this final analysis of the PALLAS trial, the addition of adjuvant palbociclib to standard endocrine therapy did not improve outcomes over endocrine therapy alone in patients with early hormone receptor-positive breast cancer.

Discrimination between 34 of 36 Possible Combinations of Three C>T SNP Genotypes in the MGMT Promoter by High Resolution Melting Analysis Coupled with Pyrosequencing Using A Single Primer Set

Due to its cost-efficiency, high resolution melting (HRM) analysis plays an important role in genotyping of candidate single nucleotide polymorphisms (SNPs). Studies indicate that HRM analysis is not only suitable for genotyping individual SNPs, but also allows genotyping of multiple SNPs in one and the same amplicon, although with limited discrimination power. By targeting the three C>T SNPs rs527559815, rs547832288, and rs16906252, located in the promoter of the O6-methylguanine-DNA methyltransferase (MGMT) gene within a distance of 45 bp, we investigated whether the discrimination power can be increased by coupling HRM analysis with pyrosequencing (PSQ). After optimizing polymerase chain reaction (PCR) conditions, PCR products subjected to HRM analysis could directly be used for PSQ. By analyzing oligodeoxynucleotide controls, representing the 36 theoretically possible variant combinations for diploid human cells (8 triple-homozygous, 12 double-homozygous, 12 double-heterozygous and 4 triple-heterozygous combinations), 34 out of the 36 variant combinations could be genotyped unambiguously by combined analysis of HRM and PSQ data, compared to 22 variant combinations by HRM analysis and 16 variant combinations by PSQ. Our approach was successfully applied to genotype stable cell lines of different origin, primary human tumor cell lines from glioma patients, and breast tissue samples.

Correlation Between Preoperative Radiological and Postoperative Pathological Tumor Size in Patients With HER2+ Breast Cancer After Neoadjuvant Chemotherapy Plus Trastuzumab and Pertuzumab

BACKGROUND

Neoadjuvant chemotherapy (NAC) in combination with anti-HER2 treatment is standard of care in patients with early HER2 positive breast cancer. Preoperative radiological evaluation is mandatory for defining the extent of surgery. In this study, we evaluated the correlation between preoperative radiological and postoperative pathological tumor size in early HER2 positive patients after neoadjuvant chemotherapy in combination with trastuzumab and pertuzumab. In a patient population with HER2 positive breast cancer, who received neoadjuvant chemotherapy and anti-HER2 treatment, the correlation between preoperative radiological and postoperative pathological tumor size was performed. Concordance of radiological and pathological tumor size was found in 55.7%, leading to more extensive breast surgery as required in 7 cases and to the underestimation of 6 neoplastic lesions before surgery, respectively.

PATIENTS AND METHODS

Seventy early HER2 positive breast cancer patients were included and retrospectively analysed. All preoperative radiological assessments as well as the tumor board decision on surgical extent and pathological evaluation were completed at the Medical University of Vienna. Preoperative radiological assessment of tumor size and lymph node status were compared with final histopathological findings. The correlation between different radiological modalities regarding tumor size was investigated.

RESULTS

Concordance of radiological and pathological tumor size was found in 55.7 % (50% by sonography and 66.7% by MRI, respectively) of patients with a nonsignificant correlation of r = 0.31 (P = .08). Of the 39 patients with pathologic complete remission (pCR), 16 were also classified as radiological complete response (rCR) while 23 of those showed a radiological stable disease or partial response. In 6 patients, radiological assessment showed a CR but invasive cancer with a tumor size range from 7 to 36 mm was found in histopathological examination. Neither menopausal status (P= .69) nor BMI (P = .60) and age (P = .50) had an impact on the correlation between radiological and histopathological tumor size. Regarding lymph node status, a statistically significant association and clinically relevant correlation between radiological and histopathological evaluation was found (r = 0.66, P < .001).

CONCLUSION

Concordance between radiology and histopathology was low regarding tumor size after NAC in combination with trastuzumab and pertuzumab, but significant regarding lymph node status.

Influence of Height on Risk and Outcome of Patients with Early Breast Cancer: A Pooled Analysis of 4,925 Patients from 5 Randomized Trials of the Austrian Breast and Colorectal Cancer Study Group (ABCSG)

<b><i>Background:</i></b> Associations between height, cancer risk and worse outcome have been reported for several cancers including breast cancer. We hypothesized that in breast cancer clinical trials, tall women should be overrepresented and might have worse prognosis. <b><i>Methods:</i></b> Data of 4,935 women, included from 1990 to 2010 in 5 trials of the Austrian Breast and Colorectal Cancer Study Group (ABCSG), were analyzed retrospectively. The primary objective was to determine differences in height distribution between the ABCSG cohort and the Austrian female population according to a cross-sectional health survey conducted by the Austrian Statistic Center in 2006 and 2007. Secondary endpoints were disease-free survival (DFS) and overall survival (OS) in different height classes and differences of body mass index (BMI) distribution. <b><i>Results:</i></b> Breast cancer patients in the ABCSG cohort were only slightly but statistically significantly smaller compared to unselected Austrian adult females (mean 164.3 vs. 164.8 cm; <i>p</i> &#x3c; 0.0001) and significantly more patients were seen in the lower body height class (50 vs. 46%; <i>p</i> &#x3c; 0.0001) when using the median as a cutoff. However, after adjustment for age, the difference in body height between the two cohorts was no longer significant (<i>p</i> = 0.089). DFS and OS in the two upper height groups (≥170 cm) compared to the two lowest height groups (&#x3c;160 cm) was not significantly different (5-year DFS: 84.7 vs. 83.0%; HR 0.91, 95% CI 0.73–1.13, <i>p</i> = 0.379; 5-year OS: 94.8 vs. 91.7%; HR 0.74, 95% CI 0.55–1.00, <i>p</i> = 0.051). The BMI of ABCSG patients was significantly higher than in the reference population (mean BMI 24.64 vs. 23.96; <i>p</i> &#x3c; 0.0001). <b><i>Conclusions:</i></b> Our results do not confirm previous findings that greater body height is associated with a higher breast cancer risk and worse outcome.

Conventional versus reverse sequence of neoadjuvant epirubicin/cyclophosphamide and docetaxel: sequencing results from ABCSG-34

BACKGROUND

Preoperative chemotherapy containing anthracyclines and taxanes is well established in early-stage breast cancer. Previous studies have suggested that the chemotherapy sequence may matter but definitive evidence is missing. ABCSG trial 34 evaluated the activity of the MUC1 vaccine tecemotide when added to neoadjuvant treatment; the study provided the opportunity for the second randomisation to compare two different anthracycline/taxane sequences.

METHODS

HER2-negative early-stage breast cancer patients were recruited to this randomised multicentre Phase 2 study. Patients in the chemotherapy cohort (n = 311) were additionally randomised to a conventional or reversed sequence of epirubicin/cyclophosphamide and docetaxel. Residual cancer burden (RCB) with/without tecemotide was defined as primary study endpoint; RCB in the two chemotherapy groups was a key secondary endpoint.

RESULTS

No significant differences in terms of RCB 0/I (40.1% vs. 37.2%; P = 0.61) or pathologic complete response (pCR) rates (24.3% vs. 25%, P = 0.89) were observed between conventional or reverse chemotherapy sequence. No new safety signals were reported, and upfront docetaxel did not result in decreased rates of treatment delay or discontinuation.

CONCLUSION

Upfront docetaxel did not improve chemotherapy activity or tolerability; these results suggest that upfront neoadjuvant treatment with anthracyclines remains a valid option.

Polygenic risk scores and breast and epithelial ovarian cancer risks for carriers of BRCA1 and BRCA2 pathogenic variants

PURPOSE

We assessed the associations between population-based polygenic risk scores (PRS) for breast (BC) or epithelial ovarian cancer (EOC) with cancer risks for BRCA1 and BRCA2 pathogenic variant carriers.

METHODS

Retrospective cohort data on 18,935 BRCA1 and 12,339 BRCA2 female pathogenic variant carriers of European ancestry were available. Three versions of a 313 single-nucleotide polymorphism (SNP) BC PRS were evaluated based on whether they predict overall, estrogen receptor (ER)-negative, or ER-positive BC, and two PRS for overall or high-grade serous EOC. Associations were validated in a prospective cohort.

RESULTS

The ER-negative PRS showed the strongest association with BC risk for BRCA1 carriers (hazard ratio [HR] per standard deviation = 1.29 [95% CI 1.25-1.33], P = 3×10-72). For BRCA2, the strongest association was with overall BC PRS (HR = 1.31 [95% CI 1.27-1.36], P = 7×10-50). HR estimates decreased significantly with age and there was evidence for differences in associations by predicted variant effects on protein expression. The HR estimates were smaller than general population estimates. The high-grade serous PRS yielded the strongest associations with EOC risk for BRCA1 (HR = 1.32 [95% CI 1.25-1.40], P = 3×10-22) and BRCA2 (HR = 1.44 [95% CI 1.30-1.60], P = 4×10-12) carriers. The associations in the prospective cohort were similar.

CONCLUSION

Population-based PRS are strongly associated with BC and EOC risks for BRCA1/2 carriers and predict substantial absolute risk differences for women at PRS distribution extremes.

Efficacy and safety of the therapeutic cancer vaccine tecemotide (L-BLP25) in early breast cancer: Results from a prospective, randomised, neoadjuvant phase II study (ABCSG 34)

BACKGROUND

Immune-based strategies represent a promising approach in breast cancer (BC) treatment. The glycoprotein mucin-1 (MUC-1) is overexpressed in more than 90% of BC patients, and is targeted by the cancer vaccine tecemotide. We have investigated the efficacy and safety of tecemotide when added to neoadjuvant standard-of-care (SoC) treatment in early BC patients.

PATIENTS AND METHODS

A total of 400 patients with HER2-early BC were recruited into this prospective, multicentre, randomised 2-arm academic phase II trial. Patients received preoperative SoC treatment (chemotherapy or endocrine therapy) with or without tecemotide. Postmenopausal women with oestrogen receptor (ER)+++, or ER++ and Ki67 < 14%, and G1,2 tumours ('luminal A' tumours) received 6 months of letrozole. Postmenopausal patients with triple-negative, ER-/+/++ and Ki67 ≥ 14%, and with G3 tumours, as well as premenopausal patients, received four cycles of epirubicin/cyclophosphamide plus four cycles of docetaxel. Primary end-point was residual cancer burden (RCB; 0/I versus II/III) at surgery. Secondary end-points included pathological complete response (pCR), safety, and quality of life.

FINDINGS

We observed no significant difference in RCB 0/I rates between patients with (36.4%) and without (31.9%) tecemotide in the overall study population (p = 0.40) nor in endocrine and chemotherapy-treated subgroups (25.0% versus 13.3%, p = 0.17; 39.6% versus 37.8%, p = 0.75, respectively). The addition of tecemotide did not affect overall pCR rates (22.5% versus 17.4%, p = 0.23), MUC-1 expression, or tumour-infiltrating lymphocytes content. Tecemotide did not increase toxicity when compared to SoC therapy alone.

INTERPRETATION

Neoadjuvant tecemotide is safe, but does not improve RCB or pCR rates in patients receiving standard neoadjuvant therapy.

Abstract OT3-06-01: Prevention and management of residual breast tissue following radical mastectomy and skin-sparing and nipple-sparing mastectomy in oncologic and high-risk breast cancer patients - A multicentre questionnaire study

1. Background

As the presumed oncological risk of skin-sparing (SSM) and nipple-sparing mastectomy (NSM) putatively relies on remaining fibroglandular tissue within the nipple-areolar-complex and the skin flap complete resection of breast parenchyma is of uttermost importance. Contrary, residual fibroglandular tissue has been detected in up to 50% of breast specimens following NSM and 13% after SSM. Studies focusing on the prevention and management of residual breast tissue (RBT) are scarce.

2. Trial design and eligibility criteria

A prospective multicenter questionnaire study addressing the subjects preventive measures, targeted flap thickness and detection and management of RBT will be performed. Certified breast care centres in Austria, Germany, Switzerland, England and the United States of America will be contacted via E-mail and asked to participate in the study. The following questions will be asked via a web-based questionnaire:

I. General data including institution, profession, number of operations the institution/ the participating surgeon performs in 1 year

II. Preventive Measures

i. In case of NSM/SSM do you determine the thickness of the subcutaneous tissue preoperatively?

ii. In case of NSM or SSM do you mark sites where fibroglandular breast tissue approximates closely to the skin preoperatively?

iii. Do you perform a frozen subareolar biopsy in the course of NSM?

iv. What do you use for breast tissue preparation to separate breast tissue from the pectoralis major muscle/from the skin?

III.Flap thickness

i. What is your target flap thickness when you perform NSM/SSM in patients with breast cancer/in high-risk patients?

ii. Are there factors that influence your target flap thickness?

IV. Detection of residual breast tissue

i. Do you screen for residual breast tissue following radical ME/NSM/SSM?

ii. What imaging modality do you use for aftercare?

iii. Is the imaging modality you use for aftercare patient-dependent or standardized?

iv. When do you perform the first breast imaging in the course of aftercare after the completion of reconstruction in patients with breast cancer/in high-risk patients?

V. Management of residual breast tissue

i. Is residual breast tissue an indication for reoperation in a patient with breast cancer and negative resection margins/in a high-risk patient?

ii. Is residual breast tissue an indication for post-mastectomy radiotherapy in a patient with breast cancer and negative resection margins?

iii. In case of residual breast tissue do you intensify your follow-up care?

3. Aims

The primary objective of the study is to assess the applied preventive and treatment measures of RBT following mastectomy in oncologic and high-risk breast cancer patients in certified breast care centres in Austria, Germany, Switzerland, England and the USA. Based on these expert opinions guidelines for the course of action regarding RBT will be developed.

4. Statistical methods

Descriptive statistics will be performed.

Citation Format: Christine Deutschmann, Georg Pfeiler. Prevention and management of residual breast tissue following radical mastectomy and skin-sparing and nipple-sparing mastectomy in oncologic and high-risk breast cancer patients - A multicentre questionnaire study [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr OT3-06-01.

Mendelian randomisation study of height and body mass index as modifiers of ovarian cancer risk in 22,588 BRCA1 and BRCA2 mutation carriers

BACKGROUND

Height and body mass index (BMI) are associated with higher ovarian cancer risk in the general population, but whether such associations exist among BRCA1/2 mutation carriers is unknown.

METHODS

We applied a Mendelian randomisation approach to examine height/BMI with ovarian cancer risk using the Consortium of Investigators for the Modifiers of BRCA1/2 (CIMBA) data set, comprising 14,676 BRCA1 and 7912 BRCA2 mutation carriers, with 2923 ovarian cancer cases. We created a height genetic score (height-GS) using 586 height-associated variants and a BMI genetic score (BMI-GS) using 93 BMI-associated variants. Associations were assessed using weighted Cox models.

RESULTS

Observed height was not associated with ovarian cancer risk (hazard ratio [HR]: 1.07 per 10-cm increase in height, 95% confidence interval [CI]: 0.94-1.23). Height-GS showed similar results (HR = 1.02, 95% CI: 0.85-1.23). Higher BMI was significantly associated with increased risk in premenopausal women with HR = 1.25 (95% CI: 1.06-1.48) and HR = 1.59 (95% CI: 1.08-2.33) per 5-kg/m2 increase in observed and genetically determined BMI, respectively. No association was found for postmenopausal women. Interaction between menopausal status and BMI was significant (Pinteraction < 0.05).

CONCLUSION

Our observation of a positive association between BMI and ovarian cancer risk in premenopausal BRCA1/2 mutation carriers is consistent with findings in the general population.

Exploratory analysis of the effect of taselisib on downstream pathway modulation and correlation with tumor response in ER-positive/HER2-negative early-stage breast cancer from the LORELEI trial

1050

Background: Taselisib (T) is an oral, potent, selective inhibitor of Class I PI3-kinase with enhanced activity against PIK3CA mutant cancer cells. Results from the LORELEI trial have demonstrated a significant improvement in ORR (objective response rate) by centrally assessed magnetic resonance imaging in all randomized patients as well as in the PIK3CA mutant (MT) cohort treated with neoadjuvant T plus letrozole (L) compared to placebo (P) plus L. Here we present the results of exploratory analyses of selected pathway-related phosphoproteins. Methods: Baseline (BL) and week3 (W3) tumor biopsies were obtained from 334 patients enrolled in the trial. Phosphoproteins (pAKT, pPRAS40 and pS6) were analyzed by IHC. BL levels as well as changes from BL to W3 were correlated with response assessed either by ORR or cell cycle arrest (Ki67 at W3 < 2.7%). Results: In the overall population, BL phosphoproteins levels were similar between the T and P arms. Higher pAKT (p < 0.001) and pPRAS40 (p = 0.004) levels were observed in MT vs wild-type (WT), whereas the opposite result was found for pS6 (p = 0.03). Treatment-induced absolute changes of phosphoproteins adjusted for BL levels were not significantly different between the T and P arms in the overall population, except for pPRAS40 with higher decrease in the T arm (p = 0.014). After stratification for PIK3CA genotype, a significantly greater decrease in expression levels was observed for pPRAS40 (p < 0.001) and pS6 (p = 0.020) in MT tumors treated with T. The treatment effects were not significantly different in the WT population. A trend for an association between decrease in pS6 levels at W3 and improved ORR was observed in the MT (p = 0.08) and T (p = 0.09) subgroups. The magnitude of pS6 suppression at W3 was higher in tumors achieving a cell cycle arrest in the MT/T subgroup (biserial correlation = -0.473). Conclusions: Exploratory analyses of phosphoproteins showed bioactivity of taselisib as indicated by downstream pathway suppression. Translational research aiming to integrate these results with additional exploratory biomarkers data is currently ongoing. Clinical trial information: NCT02273973.

REACHAUT: First-line (1L) ribociclib (RIB) + endocrine therapy (ET) in HR+, HER2- metastatic breast cancer (MBC) in the real-world setting

e12527

Background: RIB + aromatase inhibitor (AI) is approved as 1L treatment (tx) for HR+, HER2− MBC. Real-world data on efficacy and safety of RIB+AI are limited. REACHAUT, a prospective, noninterventional trial assessed the safety of RIB+AI in 1L setting in postmenopausal patients (pts) with HR+, HER2− MBC in a real-world setting. First interim analysis results about safety are presented. Methods: 75 postmenopausal pts with HR+, HER2− MBC, QTc < 450 msec, and no prior ET for advanced disease were enrolled at 13 sites. 1L chemotherapy (CT) was allowed. Results: At data cutoff (25-Jan-2019), 61 pts were evaluable for safety (ongoing, n = 44; discontinued, n = 17). Median duration of follow-up was 29 d. Median age at baseline was 65 y ( < 65 y, n = 28; ≥65 y, n = 33); ECOG performance status was 0 (n = 39) and 1 (n = 12). 42.6% had visceral (lung, liver) metastases (mets), while 34.4% had bone only mets. Most common prior tx included CT (29.5% in neoadjuvant/adjuvant/metastatic setting) and ET (41%). Pts received RIB in 1L (93.4%) and second-line (6.6%) setting. In 80.3% pts receiving RIB, the ET partner included letrozole (57.4%), exemestane (11.5%), anastrozole (9.8%). Median duration of RIB exposure was 100 d. Median time to first AE was 14 d. 83.6% pts experienced AEs with mild (63.9%) to moderate (50.8%) severity. Serious AEs were noted in 6.6% pts. Most common AEs were neutropenia (42.6%) and QTc prolongation (24.6%). 4.9% pts had hepatobiliary AEs. Due to AEs, dose adjustments (4.9%) and dose interruptions (19.8%) were needed. No deaths were reported; median PFS was not reached. Subgroup analysis by age ( < 65 y vs ≥65 y) showed that the incidence of AEs was 55.9% vs 44.1%. Neutropenia was reported in 46.4% pts aged < 65 y vs 39.3% pts aged ≥65 y; QT prolongation events were noted in 21.4% pts aged < 65 y vs 27.2% pts aged ≥65 y. Dose adjustments and dose interruptions were needed in 14.3% and 46.4% pts aged < 65 y vs 15.2% and 45.5% pts aged ≥65 y. Conclusions: Overall safety of RIB+AI in routine clinical practice in REACHAUT was consistent with that reported in the MONALEESA-2 study. In real-world setting, pt age ( < 65 y vs ≥65 y) had minimal impact on AEs. Clinical trial information: NIS006622.

Height and Body Mass Index as Modifiers of Breast Cancer Risk in BRCA1/2 Mutation Carriers: A Mendelian Randomization Study

BACKGROUND

BRCA1/2 mutations confer high lifetime risk of breast cancer, although other factors may modify this risk. Whether height or body mass index (BMI) modifies breast cancer risk in BRCA1/2 mutation carriers remains unclear.

METHODS

We used Mendelian randomization approaches to evaluate the association of height and BMI on breast cancer risk, using data from the Consortium of Investigators of Modifiers of BRCA1/2 with 14 676 BRCA1 and 7912 BRCA2 mutation carriers, including 11 451 cases of breast cancer. We created a height genetic score using 586 height-associated variants and a BMI genetic score using 93 BMI-associated variants. We examined both observed and genetically determined height and BMI with breast cancer risk using weighted Cox models. All statistical tests were two-sided.

RESULTS

Observed height was positively associated with breast cancer risk (HR = 1.09 per 10 cm increase, 95% confidence interval [CI] = 1.0 to 1.17; P = 1.17). Height genetic score was positively associated with breast cancer, although this was not statistically significant (per 10 cm increase in genetically predicted height, HR = 1.04, 95% CI = 0.93 to 1.17; P = .47). Observed BMI was inversely associated with breast cancer risk (per 5 kg/m2 increase, HR = 0.94, 95% CI = 0.90 to 0.98; P = .007). BMI genetic score was also inversely associated with breast cancer risk (per 5 kg/m2 increase in genetically predicted BMI, HR = 0.87, 95% CI = 0.76 to 0.98; P = .02). BMI was primarily associated with premenopausal breast cancer.

CONCLUSION

Height is associated with overall breast cancer and BMI is associated with premenopausal breast cancer in BRCA1/2 mutation carriers. Incorporating height and BMI, particularly genetic score, into risk assessment may improve cancer management.

Association between family history, mutation locations, and prevalence of BRCA1 or 2 mutations in ovarian cancer patients

We investigated the prevalence of germline BRCA mutations in a population‐based cohort of Austrian women diagnosed with ovarian cancer and its association with family history of cancer. We prospectively collected family pedigrees of 443 Austrian ovarian cancer patients who had been tested for the presence of a germline BRCA or 2 mutations and correlated the familial breast and ovarian cancer burden with the prevalence of BRCA mutations and disease onset. The probability of carrying a gBRCA mutation in patients without family history of cancer is 14% (95% CI 9%‐22%), as opposed to 45% (95% CI 31%‐59%) of patients with at least one family member with ovarian cancer, and 47% (95% CI 40%‐54%) if other relatives have developed breast cancer. If both breast and ovarian cancer are diagnosed in the family, the probability of carrying a germline BRCA1 or 2 mutations is 60% (95% CI 50%‐68%). germline BRCA1 or mutations in families with ovarian cancer only are commonly located in the Ovarian Cancer Cluster Regions when compared to families with both breast and ovarian cancer (P = 0.001, and P = 0.020, respectively). While gBRCA mutation carriers with ovarian cancer do not have a significantly different age at onset than patients with a family history of cancer, gBRCA1 carriers in general have an earlier onset than gBRCA2 carriers (P = 0.002) and patients without a mutation (P = 0.006). The rate of germline BRCA1 or 2 mutations in ovarian cancer patients without a family history or breast or ovarian cancer is low. However, in women with additional family members affected, the prevalence is considerably higher than previously reported.

Adjuvant denosumab in postmenopausal patients with hormone receptor-positive breast cancer (ABCSG-18): disease-free survival results from a randomised, double-blind, placebo-controlled, phase 3 trial

BACKGROUND

In postmenopausal women with hormone receptor-positive, early-stage breast cancer, treatment with adjuvant aromatase inhibitors is the standard of care, but it increases risk for osteoporosis and fractures. Results from the ABCSG-18 trial showed that use of denosumab as an adjuvant to aromatase inhibitor therapy significantly reduced clinical fractures. Disease-free survival outcomes from ABCSG-18 have not yet been reported.

METHODS

Postmenopausal patients with early, hormone receptor-positive, non-metastatic adenocarcinoma of the breast, who had completed their initial adjuvant treatment pathway (surgery, radiotherapy, or chemotherapy, or a combination) and were receiving adjuvant aromatase inhibitors, were enrolled at 58 trial centres in Austria and Sweden into this prospective, double-blind, placebo-controlled, phase 3 trial. With permuted block randomisation (block sizes 2 and 4, stratified by previous aromatase inhibitor use, total lumbar spine bone mineral density score at baseline, and type of centre), patients were assigned (1:1) to receive subcutaneous denosumab (60 mg) or matching placebo every 6 months during aromatase inhibitor therapy. The primary endpoint (previously reported) was the time to first clinical fracture after randomisation. The secondary endpoint reported here is disease-free survival (defined as time from randomisation to first evidence of local or distant metastasis, contralateral breast cancer, secondary carcinoma, or death from any cause) in the intention-to-treat population. This study is registered with EudraCT (number 2005-005275-15) and ClinicalTrials.gov (number NCT00556374), and is ongoing for long-term follow-up.

FINDINGS

Between Dec 18, 2006, and July 22, 2013, 3425 eligible patients were enrolled and randomly assigned; 1711 to the denosumab group and 1709 to the placebo group (with five others withdrawing consent). After a median follow-up of 73 months (IQR 58-95), 240 (14·0%) patients in the denosumab and 287 (16·8%) in the placebo group had disease-free survival events. Disease-free survival was significantly improved in the denosumab group versus the placebo group (hazard ratio 0·82, 95% CI 0·69-0·98, Cox p=0·0260; descriptive analysis, without controlling for multiplicity). In the denosumab group, disease-free survival was 89·2% (95% CI 87·6-90·8) at 5 years and 80·6% (78·1-83·1) at 8 years of follow-up, compared with 87·3% (85·7-89·0) at 5 years and 77·5% (74·8-80·2) and 8 years in the placebo group. No independently adjudicated cases of osteonecrosis of the jaw or confirmed atypical femoral fractures were recorded. The total number of adverse events was similar in the denosumab group (1367 [including 521 serious] adverse events) and the placebo group (1339 [515 serious]). The most common serious adverse events were osteoarthritis (62 [3·6%] of 1709 in the denosumab group vs 58 [3·4%] of 1690 in the placebo group), meniscus injury (23 [1·3%] vs 24 [1·4%]), and cataract (16 [0·9%] vs 28 [1·7%]). One (<0·1%) treatment-related death (due to pneumonia, septic kidney failure, and cardiac decompensation) occurred in the denosumab group.

INTERPRETATION

Denosumab constitutes an effective and safe adjuvant treatment for patients with postmenopausal hormone receptor-positive early breast cancer receiving aromatase inhibitor therapy.

FUNDING

Amgen.

Abstract P6-21-02: Withdrawn

This abstract was withdrawn by the authors.

Citation Format: Minichsdorfer C, Bergen E, Steger GG, Pfeiler G, Frantal S, Greil R, Fohler H, Egle D, Balic M, Fitzal F, Wette V, Exner R, Bartsch RA, Gnant M. Withdrawn [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P6-21-02.

Enhancer Domains in Gastrointestinal Stromal Tumor Regulate KIT Expression and Are Targetable by BET Bromodomain Inhibition

Gastrointestinal stromal tumor (GIST) is a mesenchymal neoplasm characterized by activating mutations in the related receptor tyrosine kinases KIT and PDGFRA. GIST relies on expression of these unamplified receptor tyrosine kinase (RTK) genes through a large enhancer domain, resulting in high expression levels of the oncogene required for tumor growth. Although kinase inhibition is an effective therapy for many patients with GIST, disease progression from kinase-resistant mutations is common and no other effective classes of systemic therapy exist. In this study, we identify regulatory regions of the KIT enhancer essential for KIT gene expression and GIST cell viability. Given the dependence of GIST upon enhancer-driven expression of RTKs, we hypothesized that the enhancer domains could be therapeutically targeted by a BET bromodomain inhibitor (BBI). Treatment of GIST cells with BBIs led to cell-cycle arrest, apoptosis, and cell death, with unique sensitivity in GIST cells arising from attenuation of the KIT enhancer domain and reduced KIT gene expression. BBI treatment in KIT-dependent GIST cells produced genome-wide changes in the H3K27ac enhancer landscape and gene expression program, which was also seen with direct KIT inhibition using a tyrosine kinase inhibitor (TKI). Combination treatment with BBI and TKI led to superior cytotoxic effects in vitro and in vivo, with BBI preventing tumor growth in TKI-resistant xenografts. Resistance to select BBI in GIST was attributable to drug efflux pumps. These results define a therapeutic vulnerability and clinical strategy for targeting oncogenic kinase dependency in GIST. SIGNIFICANCE: Expression and activity of mutant KIT is essential for driving the majority of GIST neoplasms, which can be therapeutically targeted using BET bromodomain inhibitors.

Improving comprehension of genetic counseling for hereditary breast and ovarian cancer clients with a visual tool

Objective

Genetic counseling and testing can be offered to individuals who are at high risk of carrying a breast cancer (BRCA) gene mutation. However, the content of genetic counseling could be difficult to understand due to complex medical information. The aim of this study was to investigate if comprehension can be improved with a new genetic counseling tool (NGCT hereafter; a tool that combines complex medical information with pictures, diagrams and tables) as compared to conventional oral-only genetic counseling (CGC).

Methods

207 clients attended genetic counseling for hereditary breast and ovarian cancer at the Medical University of Vienna between February 2015 and February 2016. Seventy clients participated in this study and were allocated into two groups: the first 36 participants received conventional (oral only) genetic counseling (CGC) and the following 34 participants received genetic counseling using a new genetic counseling tool (NGCT), which combines complex information with pictures, diagrams and tables. After genetic counseling, all consenting participants were invited to complete a questionnaire with seven questions evaluating their comprehension of the medical information provided.

Results

Socio-demographic backgrounds were comparable in both groups. Correct responses were significantly higher in the NGCT group compared to the CGC group (p = 0.012). NGCT also statistically improves correct response of Q1 (p = 0.03) and Q7 (p = 0.004).

Conclusion

The NGCT leads to an overall better understanding of the content of a genetic counseling session than CGC alone.