Evaluating the addition of bevacizumab to endocrine therapy as first-line treatment for hormone receptor-positive metastatic breast cancer: a pooled analysis from the LEA (GEICAM/2006-11_GBG51) and CALGB 40503 (Alliance) trials

BACKGROUND

Randomised trials comparing the efficacy of standard endocrine therapy (ET) versus experimental ET + bevacizumab (Bev) in 1st line hormone receptor-positive patients with metastatic breast cancer have thus far shown conflicting results.

PATIENTS AND METHODS

We pooled data from two similar phase III randomised trials of ET ± Bev (LEA and Cancer and Leukemia Group B 40503) to increase precision in estimating treatment effect. Primary end-point was progression-free survival (PFS). Secondary end-points were overall survival (OS), objective response rate (ORR), clinical benefit rate (CBR) and safety. Exploratory analyses were performed within subgroups defined by patients with recurrent disease, de novo disease, prior endocrine sensitivity or resistance and reported grades III-IV hypertension and proteinuria.

RESULTS

The pooled sample consisted of 749 patients randomised to ET or ET + Bev. Median PFS was 14.3 months for ET versus 19 months for ET + Bev (unadjusted hazard ratio [HR] 0.77; 95% confidence interval [CI] 0.66-0.91; p < 0.01). ORR and CBR with ET and ET + Bev were 40 versus 61% (p < 0.01) and 64 versus 77% (p < 0.01), respectively. There was no difference in OS (HR 0.96; 95% CI 0.77-1.18; p = 0.68). PFS was superior for ET + Bev for endocrine-sensitive patients (HR 0.68; 95% CI 0.53-0.89; p = 0.004). Grade III-IV hypertension (2.2 versus 20.1%), proteinuria (0 versus 9.3%), cardiovascular (0.5 versus 4.2%) and liver events (0 versus 2.9%) were significantly higher for ET + Bev (all p < 0.01). Hypertension and proteinuria were not predictors of efficacy (interaction test p = 0.33).

CONCLUSION

The addition of Bev to ET increased PFS overall and in endocrine-sensitive patients but not OS at the expense of significant additional toxicity.

TRIALS REGISTRATION

ClinicalTrial.Gov NCT00545077 and NCT00601900.

Abstract PD6-06: Impact of BRCA mutations on chemotherapy-induced loss of ovarian reserve: A prospective longitudinal study

Background: The BRCA1/2 genes are key members of the ataxia-telangiectasia mutated (ATM)-mediated DNA double strand break (DSB) repair pathway. Recent research showed that germline mutations in these genes result in DNA repair deficiency in oocytes, leading to accelerated ovarian aging as manifested by lower ovarian reserve and earlier age at natural menopause. Because we discovered that oocyte DNA repair is similarly critical in chemotherapy-induced ovarian follicle loss, we hypothesized that women with pathogenic mutations in BRCA1/2 genes may experience larger declines in ovarian reserve after chemotherapy. To gauge the degree of the chemotherapy-induced ovarian damage, we utilized serum anti-mullerian hormone (AMH), which is the most reliable current marker for assessing oocyte reserve.

Methods: Women with early stage breast cancer were enrolled before chemotherapy (Trial registration number: NCT00823654) between January 2009 and November 2017. Sera were obtained at baseline, before the initiation of treatment, and 18 to 24 months after the completion of chemotherapy. Stored sera were assayed at once for anti-mullerian hormone (AMH) and the results were adjusted for the women's age at sample collection. Of the 235 enrolled, 117 evaluable women were stratified into three groups, those never tested (based on NCCN Guidelines V 1.2018 ; n=38) and those negative (n=65) or positive (n=14) for a pathogenic BRCA mutation. Ovarian recovery was defined as the geometric mean of the post chemotherapy age-adjusted AMH levels compared to baseline.

Results: Compared to the lower risk (BRCA-untested) control group, AMH levels averaged 76% and 66% in those negative or positive for BRCA mutations (p=0.078). The geometric mean recoveries for the three groups (not tested, BRCA negative and BRCA positive) were 3.7%, 5.2% and 1.6%, respectively. The mean recovery in the BRCA mutation positive group was about one-third the 4.6% recovery in the other two groups combined (two group ANOVA, p=0.034, F=4.89). Given the potential of the ovarian recovery to be dependent on type of chemotherapy, the data were reanalyzed for all three BRCA groups after restriction to those treated with the AC-T (doxorubicin and cyclophosphamide followed by paclitaxel) regimen. Of the 108 women in the previous analysis, 83 (77%) were treated with AC-T; 25, 46 and 12 women in the three groups, respectively. The geometric mean AMH recoveries for these new groups were 3.2%, 4.7% and 1.3%. When the BRCA mutation positive group was compared with other two groups, the former had significantly worse recovery of serum AMH levels (ANOVA, p=0.044, F=4.2).

Conclusions: These data show that women with breast cancer and pathogenic BRCA mutations have striking liability to chemotherapy-induced ovarian reserve loss and may have to be preferentially counselled on fertility preservation methods. In addition, taken together with the previous data showing that women with BRCA mutations may have accelerated ovarian aging, even unaffected reproductive age individuals may have to be proactive about family building or early preservation of their fertility (Supported by NIH R01HD053112).

Citation Format: Oktay K, Bedoschi G, Goldfarb SB, Taylan E, Titus S, Palomaki GE, Cigler T, Robson M, Dickler MN. Impact of BRCA mutations on chemotherapy-induced loss of ovarian reserve: A prospective longitudinal study [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 PD6-06.

Abstract P2-07-05: A clinical calculator to predict disease outcomes in women with hormone receptor-positive advanced stage breast cancer treated with first-line endocrine therapy

Purpose: Endocrine based therapy is an effective strategy to manage hormone receptor-positive, human epidermal growth factor receptor 2-negative (HR+/HER2-) advanced breast cancer (ABC). However, nearly all patients exhibit/develop either de novo or acquired resistance. While prognostic biomarkers of endocrine responsiveness are well established for the adjuvant treatment in ER+ breast cancer, less is known regarding prognostic and predictive biomarkers of response in the first line ABC setting. We sought to develop a clinical calculator based on clinical criteria for predicting progression-free survival (PFS) and overall survival (OS) of women with HR+/HER2- ABC who will be receiving endocrine monotherapy as first-line treatment for ABC.

Methods: The development of the clinical calculator will be based on data from modern clinical trials in women with HR+/HER2- ABC. The studies to be included in the final analyses are given in Table 1. The control arm data from trials1-6 will form the training dataset (N = 1,223) and be used to construct the clinical prediction models. Variables considered include age, race, ECOG status, disease measurability, body mass index, disease-free interval, number of metastatic sites, locations of metastatic sites, prior endocrine therapy, and prior chemotherapy. Missing values will be imputed using single imputation with all variables included in the imputation model. For continuous variables, restricted cubic splines will be used to determine if non-linear effects may be more appropriate. The Lasso regression will be used as a variable selection technique to reduce the dimensionality of covariates; initially all pairwise interactions will be included in the model. Following Lasso regression, the multivariable Cox proportional hazards models will be constructed for PFS and OS including only variables retained in Lasso. The final model will be internally validated for discrimination and calibration using 10-fold cross-validation. External validation will be performed using control arm data from EGF 30008 (N = 536).

Results: To date, control arm data from four trials (trials 1-4) have been received. The preliminary results presented here are based on pooled data from C40503 and LEA, for which data elements have been harmonized. Models for predicting PFS and OS have good calibration and are associated with bias-corrected C-indices of 0.61 and 0.65, respectively. These models will be updated using pooled data from trials 1-6.

Conclusions: Our preliminary data demonstrate that clinical calculators based on baseline clinical factors can provide accurate prediction of PFS and OS in patients with HR+/HER2- ABC treated with first-line ET. If validated, these tools may be used for risk stratification in future clinical trials and to identify patients who may require more or less aggressive therapy.

Table 1:Studies to be includedTrial NumberTrial NameTrial PISample Size in Control Arm1C40503Maura Dickler152 (letrozole)2LEAMiguel Martin179 (letrozole)3FACTJonas Bergh188 (anastrozole)4FALCONJohn Robertson194 (anastrozole)5S0226Rita Mehta345 (anastrozole)6MONARCH 3Matthew Goetz165 (nonsteroidal AI)7EGF 30008Stephen Johnston536 (letrozole)

Citation Format: Polley M-YC, Dickler MN, Johnston S, Goetz MP, de la Haba J, Loibl S, Mehta RS, Bergh J, Roberston J, Barlow W, Liu H, Tenner K, Martin M. A clinical calculator to predict disease outcomes in women with hormone receptor-positive advanced stage breast cancer treated with first-line endocrine therapy [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 P2-07-05.

Abstract P6-18-19: Real-world survival of heavily pretreated patients with refractory HR+, HER2- metastatic breast cancer receiving single-agent chemotherapy - A comparison with MONARCH 1

Background

In MONARCH 1 (NCT02102490), abemaciclib demonstrated promising single-agent activity and tolerability in a population of heavily pretreated women with refractory HR+, HER2- metastatic breast cancer (MBC).1 Confirmed objective response rate (ORR) was 19.7% (95% CI: 13.3, 27.5) and at 18 months minimum follow-up median overall survival (OS) was 22.3 months. Due to the single-arm trial design of MONARCH 1, there is a need to view these results in clinical context relative to available treatment options. This study compared the OS results of abemaciclib in MONARCH 1 vs that in a real-world single-agent chemotherapy cohort with similar patient and disease characteristics.

Methods

MONARCH 1 study design and key eligibility criteria were previously described.1 The real-world cohort was based on Flatiron Health electronic health records-derived, nationally representative (USA-based) database comprising patient-level structured and unstructured data, curated via technology-enabled abstraction, for patients with MBC between January 1, 2011 through February 28, 2018. A real-world single-agent chemotherapy cohort was created based on the key eligibility criteria of MONARCH 1 and included patients diagnosed with HR+, HER2- MBC who received single-agent chemotherapy (eribulin, capecitabine, gemcitabine, or vinorelbine) following 1-2 prior chemotherapy regimens in the metastatic setting, had an ECOG PS of 0-1, and no prior CDK4 & 6 therapy. The index date was the start of the eligible single-agent chemotherapy, and patients were followed from the index date until date of death, loss to follow-up, or end of the database, whichever occurred earlier. OS results were adjusted using 2 methods (Mahalanobis distance matching and entropy balancing with bootstrapping) to account for baseline demographic and clinical differences between the real-world and trial cohorts.

Results

A real-world cohort (n=281) with eligibility criteria similar to the MONARCH 1 population (n=132) was identified. A subsequent matching based on Mahalanobis distance was performed to match MONARCH 1 population (n=108) with the real-world cohort (n=108). The matched cohorts demonstrated similar patient and disease characteristics. Median OS was 22.3 months in the abemaciclib arm vs 13.6 months in the matched cohort with an estimated hazard ratio (HR) of 0.54 (95% CI: 0.37, 0.77). Results of a sensitivity analysis performed using entropy balancing were consistent with an adjusted median OS of 12.7 months in the real-world cohort (n=281)with HR of 0.57 (95% CI from bootstrapping: 0.44, 0.78).

Conclusion

Methodological advances to adjust for potential biases, and improvements in data quality, have evolved enabling the ability to leverage a real-world cohort as an external comparator arm. This study demonstrates the ability to create a real-world chemotherapy cohort suitable to serve as a comparator for MONARCH 1. These exploratory results suggest a survival advantage and adequately place the clinical benefit of abemaciclib monotherapy in clinical context.

References

Dickler et al, CCR 2017

Citation Format: Rugo H, Dieras V, Cortes J, Patt D, Wildiers H, O'Shaughnessy J, Zamora E, Yardley DY, Carter GC, Sheffield KM, Li L, Andre VA, Derbyshire RE, Li XI, Frenzel M, Huang Y-J, Dickler MN, Tolaney SM. Real-world survival of heavily pretreated patients with refractory HR+, HER2- metastatic breast cancer receiving single-agent chemotherapy - A comparison with MONARCH 1 [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 P6-18-19.

Abstract P5-11-01: Phamacodynamic and circulating tumor DNA evaluation in a phase I study of GDC-0927, a selective estrogen receptor antagonist/ degrader (SERD)

Background: Modulation of estrogen activity and/or synthesis is the mainstay therapeutic strategy in the treatment of ER positive breast cancer. However, despite the effectiveness of available endocrine therapies, many patients ultimately relapse or develop resistance to these agents via estrogen-dependent and estrogen-independent mechanisms, including mutations in ESR1 affecting the ER ligand binding domain that drive ER-dependent transcription and proliferation in the absence of estrogen. Based on preclinical and clinical data, SERDs are expected be effective in patients harboring ESR1 mutations. Biomarker analysis was performed on plasma and tumor samples from the Phase I study of GDC-0927 in metastatic breast cancer (Dickler et al, SABCS 2017) with the goal of evaluating activity in both ESR1 mutant and wildtype tumors, and to assess ER pathway modulation.

Methods: Hotspot mutations in ESR1, PIK3CA, and AKT1 were analyzed in baseline, on-treatment and end of treatment plasma derived circulating tumor DNA (ctDNA) using the BEAMing assay in patients treated at multiple dose levels of GDC-0927. A subset of samples was analyzed with Foundation Medicine's next generation sequencing ctDNA assay (FACT), which covers genomic alterations in 62 commonly altered genes. Paired pre- and on-treatment biopsies were collected to assess ER pathway modulation. ER, PR, and Ki67 protein levels were analyzed by immunohistochemistry. Gene expression analysis was performed using Illumina's RNA Access library preparation kit followed by paired-end (2x50b, 50M reads) sequencing on the HiSeq.

Results: Baseline and on-treatment plasma samples were available for 40 patients. ESR1 and PIK3CA mutations were observed in 52% and 33% of patient baseline samples, respectively (BEAMing method). Mutant allele frequencies (MAF) generally declined in the first on-treatment samples collected for both ESR1 (16 out of 21 samples) and PIK3CA (7 out of 12 samples). The majority of the reductions were greater than 95% relative to baseline. Increases in ESR1 MAFs were observed in later time-points and were not associated with any particular ESR1 mutation. There were six instances for which an ESR1 mutation was detected in an on-treatment sample that was not detected in the baseline sample, three at L536P and one each at D538G, L536H, and S463P, and four out of six with MAFs close to the limit of detection. The FACT assay also detected alterations in CDH1, NF1, PTEN, and TP53 in baseline samples. The relationship between MAF changes and clinical benefit to GDC-0927 will be presented. A predefined, experimentally-derived set of ER target genes were evaluated in pre- and on-treatment tumor biopsy pairs from six patients. Four of the six patients showed evidence of suppression in ER pathway activity, one patient treated at the 1000 mg dose level and three at the 1400 mg dose. The degree of pathway suppression was associated with pre-treatment pathway levels and decreases of ER and Ki67 protein levels.

Conclusions: We report here evidence of consistent reduction of ESR1 and PIK3CA ctDNA in patients treated with GDC-0927. ER pathway suppression was observed at both the transcript and protein level confirming pharmacodynamic activity of the SERD.

Citation Format: Spoerke JM, Daemen A, Chang C-W, Giltnane J, Metcalfe C, Dickler MN, Bardia A, Perez Fidalgo JA, Mayer IA, Boni V, Winer EP, Hamilton EP, Bellet M, Urruticoechea A, Gonzalez Martin A, Cortes J, Martin M, Gates M, Cheeti S, Fredrickson J, Wang X, Friedman LS, Liu L, Li R, Chan IT, Mueller L, Milan S, Lauchle J, Humke EW, Lackner MR. Phamacodynamic and circulating tumor DNA evaluation in a phase I study of GDC-0927, a selective estrogen receptor antagonist/ degrader (SERD) [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 P5-11-01.

Abstract P6-12-12: Improvement in sexual function over time in premenopausal women with breast cancer

Background: There is evidence that many cancer survivors live with sexual dysfunction that impacts their quality of life. It is essential to identify factors that influence the development of sexual symptoms and understand their trajectory over time in order to guide potential interventions to treat sexual dysfunction. Most studies to date have been cross-sectional and longitudinal studies are needed to understand the change of sexual function over time. This study aims to investigate and describe the factors that impact sexual health and dysfunction in breast cancer patients during and after their cancer treatment.

Methods: A longitudinal prospective trial is being conducted in premenopausal women 18-50 years of age with breast cancer being treated at MSKCC. Validated questionnaires on sexual health and function were administered to patients after they were diagnosed with breast cancer, but before they initiated cancer treatment and at one-year follow-up after initiation of primary breast cancer therapy. Demographic and treatment information was also collected. The female sexual function index (FSFI) total and individual domain scores were calculated. Baseline and 12-month scores were compared using paired t-tests. Multivariable linear regression was used to assess individual variable associations with 12-month FSFI total scores controlling for baseline scores.

Results: 127 women were eligible for analysis at the time of this abstract and had a median age of 41. Eighty-nine percent of tumors were estrogen receptor positive and 24.4% were HER-2 overexpressing. Eighty-nine percent of patients received chemotherapy, 61.4% received Tamoxifen and 23% received a LHRH agonist in combination with an aromatase inhibitor. Mean FSFI total score was 20.4 at baseline and 21.2 at 12-months post diagnosis. More than half of women met FSFI criteria for sexual dysfunction (FSFI score&lt;26) at baseline (57.5%) and 12-months (55.2%). Small increases in sexual activity were seen with 27.8% of patients inactive at baseline compared to 23.2% at 12 months. Similarly, women engaging in sexual activity more than once a week increased from 9.5% to 16.8%. Desire (libido) significantly improved (p = 0.023) from baseline to 12 months. Controlling for baseline score, younger age and treatment with tamoxifen were associated with better 12-month scores (p &lt; 0.05).

Conclusions: Mean FSFI scores in our patients with breast cancer before and after treatment are consistent with scores from other studies looking at cancer patients and are lower than those of healthy women. In the peri-diagnosis period patients had worse sexual function that showed signs of small improvements 12 months after initiation of treatment, especially in the desire domain. Patients are being followed to see if sexual function continues to improve over time, to better understand the factors causing sexual dysfunction in these patients and to determine the best time to intervene in order to improve symptoms.

Citation Format: Goldfarb SB, Kamer S, Baser R, Quistorff J, Gemignani ML, Dickler M. Improvement in sexual function over time in premenopausal women with breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P6-12-12.

Abstract P5-21-02: Efficacy and safety of abemaciclib in patients with liver metastases in the MONARCH 1, 2, and 3 studies

Background:

Abemaciclib is an oral, selective inhibitor of cyclin-dependent kinases 4 & 6 that is dosed on a twice daily continuous schedule. In patients (pts) with hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) advanced breast cancer (ABC), abemaciclib has demonstrated clinical efficacy with a tolerable safety profile when administered as monotherapy in MONARCH 1 (NCT02102490), in combination with fulvestrant in MONARCH 2 (NCT02107703), and in combination with non-steroidal aromatase inhibitors (NSAI) in MONARCH 3 (NCT02246621). Inducing tumor response and delaying disease progression is of critical need in pts with liver metastases (mets).

Methods:

An exploratory subgroup analysis was conducted in pts with liver mets at baseline across the MONARCH 1, 2, and 3 studies. All pts had HR+, HER2- ABC. The primary endpoint of MONARCH 1 was objective response rate (ORR), and the primary endpoint of MONARCH 2 and 3 was investigator-assessed progression-free survival (PFS). Analysis methods for these endpoints were previously described. Key enrollment criteria and dosing information are listed in Table 1.

Table 1. Eligibility criteria and dosing information for the MONARCH 1, 2, and 3 studiesKey enrollment criteriaMONARCH 1MONARCH 2MONARCH 3Prior endocrine therapyProgressed on or after ETProgressed while receiving adjuvant or first-line ET, or ≤ 12 months from the end of adjuvant ETET naïve or disease relapse &gt;12 months after (neo)adjuvant ETChemotherapy regimens in advanced setting1 or 200Visceral crisisNo restrictionNot permittedNot permittedDose and Schedule   abemaciclib200 mg, twice daily, continuous150 mg1, twice daily, continuous150 mg, twice daily, continuousfulvestrant-500 mg, per label-anastrozole2--1 mg, dailyletrozole2--2.5 mg, daily1post-amendment; 2physician's choice of NSAI (anastrozole or letrozole); ET: endocrine therapy

Results:

Efficacy results of pts with liver mets are described in Table 2. The most frequent adverse events observed in pts with liver mets in MONARCH 1 were diarrhea, nausea, and fatigue and in the abemaciclib arms of MONARCH 2 and 3 were diarrhea, neutropenia, and nausea.

Table 2. PFS and response rates of pts with liver mets in MONARCH 1, 2, and 3 MONARCH 1MONARCH 2 abemaciclib armMONARCH 2 placebo armMONARCH 3 abemaciclib armMONARCH 3 placebo armPts with liver mets, n93115594830PFS, HR (95% CI)N/A.45 (.31, .64).47 (.25, .87)Median PFS, months5.611.63.115.07.2ORR, n (%)20 (21.5)54 (47.0)9 (15.3)26 (54.2)6 (20.0)CBR, n (%)39 (41.9)77 (67.0)21 (35.6)32 (66.7)12 (40.0)CBR: clinical benefit rate (complete response [CR] + partial response [PR] + stable disease ≥6 months); HR: hazard ratio; ORR: objective response rate (CR+PR); PFS: progression-free survival; pts: patients

Conclusions:

The results suggest that the combination of abemaciclib and endocrine therapy was an effective treatment option in pts with liver metastases, a population deriving modest benefit from single-agent endocrine therapy. Tolerability results were generally consistent with the safety populations previously reported for each study.

Citation Format: Di Leo A, Dickler M, Sledge GW, Toi M, Forrester T, Nanda S, Koustenis A, Bourayou N, Johnston S. Efficacy and safety of abemaciclib in patients with liver metastases in the MONARCH 1, 2, and 3 studies [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P5-21-02.

Abstract PD5-10: A first-in-human phase I study to evaluate the oral selective estrogen receptor degrader (SERD), GDC-0927, in postmenopausal women with estrogen receptor positive (ER+) HER2-negative metastatic breast cancer (BC)

Background: Modulation of estrogen activity and/or synthesis is the mainstay therapeutic strategy in the treatment of ER+ BC. However, despite the effectiveness of available endocrine therapies, many patients ultimately relapse or develop resistance to these agents via estrogen-dependent and estrogen-independent mechanisms, including mutations in ESR1 affecting the ER ligand binding domain that drive ER-dependent transcription and proliferation in the absence of estrogen. ER antagonists that are efficacious against ligand-dependent and ligand-independent, constitutively active ESR1 mutant tumors may be of substantial therapeutic benefit. GDC-0927 (formerly known as SRN-927) is a novel, potent, non-steroidal, orally bioavailable, selective ER antagonist/ER degrader (SERD) that induces tumor regression in ER+ BC patient-derived xenograft models.

Methods: A phase I dose escalation study with 3+3 design was conductedin postmenopausal women with ER+ (HER2-) metastatic BC (progressing ≥ 6 months on endocrine therapy and with ≤ 2 prior chemotherapies in the advanced or metastatic setting) to determine the safety, pharmacokinetics (PK) and the recommended Phase 2 dose (RP2D) of GDC-0927. Pharmacodynamic (PD) activity was assessed with [18F]-fluoroestradiol (FES)-PET scans. Plasma PK samples (after single dose and at steady state), CT scans, and when feasible, pre and on-study tumor biopsies were obtained

Results: From March 16, 2015 to March 17, 2017 patients (pts) with a median age of 53 years (range 44-69) and a median number of prior therapies for MBC 4 (range 1-7) were enrolled at 3 total daily dose levels (600, 1000, 1400 mg) once daily (QD) given orally with fasting (n = 12). Increases in GDC-0927 exposure were approximately dose proportional. Treatment related adverse events (AEs) were all grade 1 or 2. The most common treatment-related AEs were nausea (54%, n = 7), diarrhea (46%, n = 6), elevated aspartate aminotransferase (39%, n = 5) and anemia, constipation, (each 31%, n = 4). Treatment interruption was required for 2 pts due to nausea and vomiting. Of those pts with FES-PET avid disease at baseline (9 of 12), all post-therapy scans showed complete or near complete (&gt; 90%) suppression of FES uptake to background levels, including pts with ESR1 mutations. Evidence of reduced ER levels and Ki67 staining was observed in on-treatment biopsies. Five of 12 pts (1 at 600 mg and 4 at 1400 mg) were on study ≥ 24 weeks (CBR = 41.6 %) with the best overall response of stable disease with 1 patient (ESR1 mt+ D538G) on study for over 490 days. There were no dose limiting toxicities and no SAEs related to study drug. R2PD was 1400 mg and was selected for single arm dose-expansion which is now complete with last patient enrolled on March 17, 2017. Updated results from dose-escalation and dose-expansion will be presented at the meeting (N = 43).

Conclusions: GDC-0927 appears well-tolerated to date with PK exposure supporting QD dosing, evidence of robust PD target engagement, and encouraging anti-tumor activity in heavily pretreated pts with advanced or metastatic ER+ BC, including pts with ESR1 mutations.

Citation Format: Dickler MN, Villanueva R, Perez Fidalgo JA, Mayer IA, Boni V, Winer EP, Hamilton EP, Bellet M, Urruticoechea A, Gonzalez-Martin A, Cortes J, Martin M, Giltnane J, Gates M, Cheeti S, Fredrickson J, Wang X, Friedman LS, Spoerke JM, Metcalfe C, Liu L, Li R, Morley R, McCurry U, Chan IT, Mueller L, Milan S, Lauchle J, Humke EW, Bardia A. A first-in-human phase I study to evaluate the oral selective estrogen receptor degrader (SERD), GDC-0927, in postmenopausal women with estrogen receptor positive (ER+) HER2-negative metastatic breast cancer (BC) [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr PD5-10.

Oncologist use and perception of large panel next-generation tumor sequencing

BACKGROUND

Genomic profiling is increasingly incorporated into oncology research and the clinical care of cancer patients. We sought to determine physician perception and use of enterprise-scale clinical sequencing at our center, including whether testing changed management and the reasoning behind this decision-making.

PATIENTS AND METHODS

All physicians who consented patients to MSK-IMPACT, a next-generation hybridization capture assay, in tumor types where molecular profiling is not routinely performed were asked to complete a questionnaire for each patient. Physician determination of genomic 'actionability' was compared to an expertly curated knowledgebase of somatic variants. Reported management decisions were compared to chart review.

RESULTS

Responses were received from 146 physicians pertaining to 1932 patients diagnosed with 1 of 49 cancer types. Physicians indicated that sequencing altered management in 21% (331/1593) of patients in need of a treatment change. Among those in whom treatment was not altered, physicians indicated the presence of an actionable alteration in 55% (805/1474), however, only 45% (362/805) of these cases had a genomic variant annotated as actionable by expert curators. Further evaluation of these patients revealed that 66% (291/443) had a variant in a gene associated with biologic but not clinical evidence of actionability or a variant of unknown significance in a gene with at least one known actionable alteration. Of the cases annotated as actionable by experts, physicians identified an actionable alteration in 81% (362/445). In total, 13% (245/1932) of patients were enrolled to a genomically matched trial.

CONCLUSION

Although physician and expert assessment differed, clinicians demonstrate substantial awareness of the genes associated with potential actionability and report using this knowledge to inform management in one in five patients.

CLINICAL TRIAL NUMBER

NCT01775072.

Abstract P6-12-01: Phase II study of taselisib (GDC-0032) plus fulvestrant in HER2-negative, hormone receptor-positive advanced breast cancer: Analysis by PIK3CA and ESR1 mutation status from circulating tumor DNA

Background:

The phosphatidylinositol 3-kinase (PI3K) pathway is frequently dysregulated in hormone receptor (HR)-positive breast cancer (BC), with activating mutations of PIK3CA detected in ~35–45% of patients (pts). Acquired mutations in the ESR1 gene, which encodes estrogen receptor α, may be associated with resistance to aromatase inhibitor (AI) therapy. Taselisib is a potent and selective PI3K inhibitor, with greater selectivity against mutant PI3Kα isoforms than wild-type (WT) via a unique mechanism. In phase I studies, taselisib plus fulvestrant had clinical activity and manageable tolerability in pts with HR-positive BC. We report exploratory analyses of PIK3CA and ESR1 from circulating tumor DNA (ctDNA).

Methods:

In this phase II, open-label, single-arm study (PMT4979g; NCT01296555), pts were postmenopausal with HER2-negative, HR-positive locally advanced or metastatic BC and progression or non-response to ≥1 prior endocrine therapy in the adjuvant or metastatic setting. Pts received taselisib (6 mg capsule orally, daily) plus fulvestrant (500 mg intramuscular on Days 1 and 15 of Cycle 1, then Day 1 of each 28-day cycle) until disease progression or unacceptable toxicity. PIK3CA-mutation testing on archival tumor tissue used the cobas® PIK3CA Mutation Test. The Sysmex Inostics' BEAMing Digital PCR platform was used for ctDNA analysis of ESR1 and PIK3CA mutations (pre-dose on Cycle 1, Day 1). Primary endpoints were objective response rate (ORR) and clinical benefit rate (CBR) in all pts and those with PIK3CA mutations. ORR was confirmed complete response (cCR) and confirmed partial response (cPR). CBR was cCR, cPR, or stable disease for ≥6 months. Secondary endpoints included safety, efficacy, pharmacokinetics, and exploratory biomarker analysis.

Results:

60 pts were enrolled. Median age was 61.5 years (range 31–82). In the metastatic setting, pts had received prior chemotherapy (21.7%) and prior hormonal therapy (50.0%). 86.7% of pts had received prior treatment with an AI. 45 pts had PIK3CA mutation status from archival tumor tissue and ctDNA testing; concordance was 86.7% (39/45). ctDNA analysis, vs archival tumor tissue testing, identified 4 pts and 9 pts with PIK3CA mutations from pts with WT and unknown PIK3CA mutation status, respectively.

Based on ctDNA analysis (N=60), 13 pts (21.7%) had mutations in both ESR1 and PIK3CA, 21 pts (35.0%) were 'mutation not detected' (MND) for both genes, 8 (13.3%) had ESR1 mutations and PIK3CA MND, and 18 (30.0%) had ESR1 MND and PIK3CA mutations.

In pts with measurable disease at baseline, confirmed responses (all partial) were: PIK3CA mutation, 38.1% (8/21); PIK3CA MND, 8.7% (2/23); all pts, 22.7% (10/44). CBRs were: PIK3CA mutation, 42.9%; PIK3CA MND, 17.4%; all pts, 29.5%. ORR and CBR from ctDNA analyses were similar to archival tumor tissue data.

Conclusions:

ctDNA analysis identified PIK3CA mutations in pts with previously unknown or WT mutation status from archival tumor tissue; ORR and CBR were similar to those from archival tumor tissue suggesting that PIK3CA mutation testing from ctDNA may be used as a surrogate when tissue is unavailable. 21.7% of pts had mutations in both ESR1 and PIK3CA.

Citation Format: Dickler MN, Saura C, Oliveira M, Richards DA, Krop IE, Cervantes A, Stout TJ, Jin H, Savage HM, Wilson TR, Baselga J. Phase II study of taselisib (GDC-0032) plus fulvestrant in HER2-negative, hormone receptor-positive advanced breast cancer: Analysis by PIK3CA and ESR1 mutation status from circulating tumor DNA [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P6-12-01.

Abstract P4-21-34: Phase II study of gemcitabine, trastuzumab, and pertuzumab for HER2-Positive metastatic breast cancer after prior pertuzumab-based therapy

Background: The combination of taxanes with trastuzumab (H) and pertuzumab (P) for first line treatment of HER2-positive metastatic breast cancer (MBC) is associated with improved progression-free survival (PFS) and overall survival (OS). Treatment per physician's choice with anti-HER2 therapy after second line therapy is associated with a median PFS of 3 months. While continued use of H in therapeutic combinations after progression on H-based therapy is common, the efficacy of continuing HP-based treatment after progression on P-based therapy is unknown.

Methods: This is a single arm phase II trial of gemcitabine (G) with HP. Eligible patients had HER2-positive (IHC 3+ or FISH ≥ 2.0) MBC with prior HP-based treatment and ≤ 3 prior chemotherapies. Patients received G (1200 mg/m2) on days 1 and 8 of a q 3 week (w) cycle, and H (8 mg/kg load → 6 mg/kg) and P (840 mg load → 420 mg) q3w. The primary endpoint is PFS at 3 months. Secondary endpoints include OS, safety and tolerability. An exploratory endpoint is to compare PFS by RECIST criteria versus 18-F FDG-PET response criteria. Using a Simon optimal 2-stage design, 21 patients were enrolled in stage 1. The successful 3-month PFS rate for stage 1 was set at 57% to allow accrual to stage 2 for a total of 45 patients. The study therapy will be considered successful if at least 27/45 (60%) patients are progression free at 3 months.

Results: As of June 9, 2016, 28 patients are enrolled; 21 are evaluable at 3 months and 7 have not had 3-month evaluation. At 3 months, 16/21 (76%) are progression free; 5 patients have progressed. The 3 month-PFS results for evaluable patients will be updated. There are no cardiac or febrile neutropenic events to date. Initially, 5 of 22 (23%) patients required G dose reduction (4 due to grade 3 neutropenia and 1 due to grade 3 vomiting) and the study was amended to lower initial G dose to 1000 mg/m2.

Conclusions: The preliminary 3 month-PFS is 76% (95% CI 55% to 89%) in evaluable patients, and updated data will be presented. These findings suggest clinical benefit when P is continued beyond progression.

Citation Format: Iyengar NM, Smyth L, Lake D, Gucalp A, Singh JC, Traina TA, DeFusco P, Dickler MN, Fornier MN, Goldfarb S, Jhaveri K, Modi S, Troso-Sandoval T, Argolo D, Jack K, Ulaner G, Jochelson M, Baselga J, Norton L, Hudis CA, Dang CT. Phase II study of gemcitabine, trastuzumab, and pertuzumab for HER2-Positive metastatic breast cancer after prior pertuzumab-based therapy [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P4-21-34.

Abstract P1-09-14: Breast carcinoma with 21-gene recurrence score lower than 18: Rate of distant metastases in a large series with clinical follow-up

Background: The 21-gene recurrence score (RS) estimates the likelihood of distant recurrence and the benefit from chemotherapy in patients with early-stage node-negative, estrogen receptor (ER)-positive, HER2-negative breast carcinoma. The use of the assay resulted in a substantial reduction in adjuvant chemotherapy usage. In this study, we reviewed the outcome of patients with node-negative, ER+/HER2- breast cancer and low recurrence score treated at our center to further verify the prognostic value of the assay.

Design: We identified breast cancer patients treated at our center between 09/2008 and 08/2013 with ER-positive, HER2-negative breast cancer and known RS. We reviewed clinicopathological characteristics, RS, treatment and outcome data. The Institutional Review Board approved the study.

Results: We identified 1406 consecutive patients with early stage node negative ER+/HER2- breast cancer and low RS [RS 0-10: 510 (36%), RS 11-17: 896 (64%)] in the study period. The median age at breast cancer diagnosis was 56 years (range 22-90). Sixty-three (4%) patients were &lt;40 years old at breast cancer diagnosis. A total of 1362 (97%) patients received endocrine therapy, and 170 (12%) received chemotherapy. The median follow up time was 46 months (range 1-85). Six (0.4%) of the 1406 patients developed biopsy proven distant metastases within 5 years of breast cancer diagnosis, 5 of which were in the RS 11-17 group (Table 1). Three of the 5 patients with RS 11-17 and distant metastases were younger than 40 years old at breast cancer diagnosis. In the RS 11-17 group, the absolute incidence of distant metastases among patients with breast cancer diagnosed at age younger than 40 years old is 7.1% (3/42), whereas the absolute incidence of distant metastases among patients ≥40 years is 0.2% (2/854).

Conclusion: Our results suggest that young age (&lt;40 years old) might be a negative prognostic factor even in patients with low RS. Analysis of data from other studies is necessary to further validate this observation.

Table 1. Clinicopathologic characteristics of the 6 patients with ER-positive, HER2-negative, node-negative breast carcinoma of recurrence score &lt;18 who developed distant metastasisPatients#1#2#3#4#5#6Age at diagnosis (years)505437713839Family history of breast/ ovarian cancerNoYesNoNoNoYesPersonal history of breast carcinomaNoIpsilateral DCISNoIpsilateral DCISNoNoTumor typeILCIDCIDCIDCIDCIDCTumor size (cm)2.11.32.72.31.62.1Tumor Grade222223LVINoNoNoNoYesNoER (%)909595959595PR (%)30585757595Oncotype DX RS51212131417SurgeryBTMTMBTMBCSBCSBTMRadiationNoNoNoYesYesNoEndocrine therapyYesYesYesYesNoYesChemoNoNoCMFNoNoNoTime interval to metastasis (months)584125204812Site of metastasisBoneMultipleLungMultipleMultipleBoneFollow-up (months)725359647142SurvivalAWDAWDAWDDODAWDAWDAbbreviations: RS, recurrence score; ILC, invasive lobular carcinoma; IDC, invasive ductal carcinoma; LVI, lymphovascular invasion; BTM, bilateral total mastectomy; TM, total mastectomy; BCS, breast conserving surgery; CMF, cyclofosphamide, metotrexate and 5-fluorouracil. AWD, alive with disease; DOD, died of disease.

Citation Format: Wen HY, Krystel-¬Whittemore M, Patil S, Pareja F, Bowser ZL, Dickler M, Norton L, Morrow M, Hudis C, Brogi E. Breast carcinoma with 21-gene recurrence score lower than 18: Rate of distant metastases in a large series with clinical follow-up [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P1-09-14.

Abstract OT2-01-07: A phase 2 study of abemaciclib plus pembrolizumab for patients with hormone receptor positive (HR+), HER2 negative (HER2-) metastatic breast cancer (MBC)

Background:

Abemaciclib is a small molecule inhibitor of both cyclin-dependent kinase (CDK) 4 and CDK6 administered orally twice daily on a continuous schedule. In I3Y-MC-JPBA, a phase I study, abemaciclib demonstrated acceptable safety, tolerability, and single-agent activity as monotherapy in different tumor types, including HR+ MBC (Patnaik A,et al. Cancer Discov 2016;6:1–14). In MONARCH 1, a phase 2 study, abemaciclib demonstrated a 19.7% objective response rate (ORR) with a median duration of response (DoR) of 8.6 months, median progression-free survival (PFS) of 6.0 months, and clinical benefit rate (CBR) of 42.4% in patients with HR+, HER2- MBC whose disease progressed on or after endocrine therapy and chemotherapy (Dickler, M. et al. American Society of Clinical Oncology (ASCO), abstract #510 (2016).). Pembrolizumab is a humanized monoclonal antibody against the programmed death receptor-1 (PD-1) protein that has shown preliminary efficacy in single-arm monotherapy trials in ER+/HER2- advanced breast cancer.

Trial design:

This open-label, phase 2 study will evaluate the safety and preliminary efficacy of abemaciclib 150 mg given orally every 12 hours on days 1-21 of a 21-day cycle in combination with intravenous pembrolizumab 200 mg on day 1 of a 21-day cycle in approximately 75 patients with stage IV non-small cell lung cancer or HR+, HER2- MBC (ClinicalTrials.gov NCT02779751). The study will include 3 disease-specific cohorts, each with approximately 25 patients. Only the HR+, HER2- MBC cohort will be presented here.

Eligibility criteria:

Eligible patients for the MBC cohort include women with confirmed HR+, HER2- MBC who have completed at least 1 but no more than 2 prior chemotherapy regimens in the metastatic setting; will provide tumor tissue prior to and after treatment (cycle 3, day 1); have measurable disease (RECIST v.1.1), adequate organ function, an ECOG performance status ≤1, and a life expectancy ≥12 weeks; are ≥18 yrs of age and able to swallow oral medications; and have not received treatment with any CDK 4 and 6 inhibitors or PD-1 or PD-L1 inhibitors.

Specific aims:

The primary objective is to characterize the safety profile of the combination of abemaciclib and pembrolizumab. Key secondary objectives include ORR, DoR, disease control rate (DCR), PFS, overall survival (OS), and characterization of pharmacokinetics.

Statistical methods:

The safety population includes patients who received at least one dose of study drug. ORR, DoR, DCR, and PFS analyses will be evaluated according to RECIST v.1.1 and irRECIST for disease progression. Time-to-event variables, such as DoR, PFS, and OS, will be estimated by Kaplan-Meier methodology. An interim analysis of safety and preliminary efficacy may occur for each cohort after all patients have completed (or discontinued from) approximately 24 weeks of treatment. The final analysis of OS will occur based on data collected for approximately 12 months after the last patient receives treatment.

Target accrual:

Approximately 75 patients are planned for the trial; 25 patients will comprise the MBC cohort.

Contact information: 1-877-CTLILLY (1-877-285-4559).

Citation Format: Rugo H, Tolaney S, Dickler M, Kabos P, Ho C-L, Wildiers H, Jerusalem G, Alés-Martínez JE, Hossain A, Johnston E, Gianni L. A phase 2 study of abemaciclib plus pembrolizumab for patients with hormone receptor positive (HR+), HER2 negative (HER2-) metastatic breast cancer (MBC) [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr OT2-01-07.

Abstract P4-11-06: Feasibility of a non-hormonal vaginal moisturizer in postmenopausal cancer survivors

Objectives: This is a single-arm prospective longitudinal clinical trial investigating the feasibility of using a non-hormonal hyaluronic acid (HLA) vaginal gel (Hydeal-D) to improve estrogen deprivation vaginal health symptoms in postmenopausal women with a history of hormone receptor-positive cancer.

Methods: Preliminary data from an ongoing clinical trial were examined. Demographics, medical information, and clinical assessment from breast cancer patients enrolled on study at baseline (n=23) and at 4-6 weeks (n=18) are presented. Eligible participants included those with a history of breast cancer receiving treatment with an aromatase inhibitor (AI) at the time of enrollment. Furthermore, participants could not have evidence of disease and had to have completed treatment for at least 3 months and no longer than 5 years (excluding AIs). Study participants were instructed to use HLA daily for 2 weeks, then 3 times per week for 12-14 weeks. Study outcomes include: pelvic exam results as recorded on a clinician evaluation form with the Vaginal Assessment Scale (VAS); patient-reported outcomes (PROs) of the Sexual Activity Questionnaire (SAQ), Sexual Self-Schema Scale, and Female Sexual Function Index (FSFI); PROMIS sexual function items; and exploratory items.

Results: The mean age was 56 years (range, 42-75). Seventy-four percent (17/23) were married or living with a partner. Fifty-seven percent (13/23) reported sexual activity with a partner at baseline, which was 72% (13/18) at 4-6 weeks. On the VAS, 65% (15/23) reported symptoms of severe dryness at baseline and 61% (14/23) reported severe dyspareunia; these reported symptoms decreased to 6% (1/18) and 6% (1/18), respectively, at 4-6 weeks. Vaginal pH scores were greater than 6.5 in 30% (7/23) at baseline; by 4-6 weeks, only 22% (4/18) had a pH in this elevated range. At baseline, 78% (18/23) had minimal moisture and 22% (5/23) had no vaginal moisture seen on exam; by 4-6 weeks, 11% (2/18) had normal moisture and 89% (16/18) had minimal moisture. Pain with pelvic exams declined over time—87% (20/23) had pain at baseline, with 22% (5/23) rating it as severe, and 78% (14/18) had pain at 4-6 weeks, with none of the women rating their pain as severe. Forty-eight percent (11/23) indicated confidence about future sexual activity at baseline, which was 56% (10/18) at 4-6 weeks. Level of concern about sexual/vaginal health was measured on a scale of 0-10, with greatest concern rated as a 9 or 10. Sixty-one percent (14/23) of the women fell into this range at baseline; the percentage decreased to 28% (5/18) at 4-6 weeks.

Conclusions:

Preliminary findings suggest that an HLA vaginal gel may improve vaginal/sexual health issues and concerns of breast cancer survivors both in their perceived symptoms and on clinical exam; however, further study is needed to examine if these promising trends continue over time and to determine the ideal frequency of product administration.

Citation Format: Carter J, Seidel B, Stabile C, Dickler M, Goldfrank D, Baser R, Goldfarb S. Feasibility of a non-hormonal vaginal moisturizer in postmenopausal cancer survivors. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P4-11-06.

Abstract ES4-1: Longitudinal strategies in ER+ disease

Endocrine therapy is a relatively well-tolerated treatment for hormone receptor-positive (HR+) breast cancer. This therapy can be offered as first-line treatment before initiation of chemotherapy in patients with manageable symptoms from their disease and no evidence of clinically significant compromise of visceral organ function. Targeting the estrogen receptor pathway with agents such as the aromatase inhibitors, tamoxifen and fulvestrant can provide effective therapy with a durable response to treatment for some patients. This presentation will review clinical trial data to guide choice of endocrine therapy and the sequential use of these agents in patients with endocrine-responsive disease. Within HR+ breast cancer, there is molecular diversity that can influence responsiveness to endocrine therapy. In addition, recent insight into the complex interactions between the estrogen receptor and cell cycle survival and/or growth factor signalling pathways have uncovered potential mechanisms of endocrine therapy resistance in HR+ breast cancer. This improved understanding has led to new options for treatment. We will review the clinical trial evidence that supports the addition of a cell cycle inhibitor, palbociclib, to first-line letrozole and second-line fulvestrant. We will also review evidence supporting the combination of an mTOR inhibitor, everolimus, to second- or third-line exemestane. These targeted agents increase progression-free survival when added to endocrine therapy, however at the present time, there is no benefit in overall survival. With this limitation in mind, we will review the side effects of these agents, weigh the toxicity and potential benefits, and examine if patient and/or tumor-based factors may help to determine which patients are best suited for these agents. Lastly, we will discuss the subset of patients with bone-only HR+ disease, and the complexities of assessing imaging and their response to therapy.

Citation Format: Dickler M. Longitudinal strategies in ER+ disease. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr ES4-1.

Abstract P2-16-12: An exploratory analysis of the role of dasatinib in preventing progression of disease in bone in patients with metastatic breast cancer

Introduction: The role of dasatinib, an oral SRC inhibitor is being explored for the treatment of metastatic breast cancer. In a phase I study, we previously established that the combination of dasatinib and weekly paclitaxel was feasible. The activity of this combination is currently being explored in an ongoing phase II trial. Since Src kinase has a major role in osteoclast function and dasatinib has established anabolic and anti-resorptive effects in bone in vitro, we hypothesized that patients receiving this combination would have good control of osseous metastases and primarily develop progression of disease in sites other than bone.

Patients and methods: Patients were included in this analysis if they participated in the phase I or II metastatic breast cancer studies and received dasatinib at or above the recommended phase II dose of 120mg with paclitaxel (80mg/m2 day 1 and 8 of each 21day cycle). Patients who discontinued therapy for reasons other than progression were excluded. Per protocol, patients were required to discontinue bisphosphonates or other bone modulating agents for the first 8 weeks of study due to the potential for hypocalcaemia. Thereafter, they were permitted to receive these agents at the discretion of their treating physician. Patients provided serum samples for correlative studies. Assessment of N-telopeptide of type 1 collagen (NTX), a product of mature bone collagen that reflects bone specific resorption, is planned.

Results: The median age of the 24 patients who met criteria for analysis was 50y (37 - 66y). Of these, 15 (63%) had ER+ disease, and 24 (100%) were negative for human epidermal growth factor receptor (HER2). At study entry, 17 (71%) patients had bone involvement. Following the initial eight week moratorium, 7 (29%) patients received a bisphosphonate or rank ligand inhibitor during treatment with dasatinib + paclitaxel. Patients received a median 2 months (range 1-23) of dasatinib + paclitaxel therapy. To date, 3 (13%) continue on therapy, and 21 (88%) have had progression of disease. Among patients who progressed, 18 (86%) have progressed in visceral sites and only 3 (14%) progressed in bone. Analyses of serum NTX levels are ongoing and will be compared by site of progression.

Conclusion: The potential role of serum NTX as a predictive biomarker of benefit from dasatinib and paclitaxel is being explored and updated results will be presented.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P2-16-12.

A Phase I dose-escalation study of the VEGFR inhibitor tivozanib hydrochloride with weekly paclitaxel in metastatic breast cancer

Tivozanib is a potent selective tyrosine kinase inhibitor (TKI) of vascular endothelial growth factor receptors (VEGFRs) 1, 2, and 3. This Phase Ib study investigated the safety/tolerability, pharmacokinetics (PK), and activity of tivozanib with weekly paclitaxel in metastatic breast cancer (MBC). MBC patients with no prior VEGFR TKI treatment received daily oral tivozanib (3 weeks on, 1 week off) with weekly paclitaxel 90 mg/m(2). Standard 3 + 3 dose escalation was used; tivozanib cohorts (C) included C1 0.5 mg, C2 1.0 mg, and C3 1.5 mg. Assessments included Response Evaluation Criteria in Solid Tumors response, PK, and vascular function. Eighteen patients enrolled. Toxicities in >20 % of patients included fatigue, alopecia, nausea, diarrhea, peripheral sensory neuropathy, and hypertension. Grade 3/4 toxicities in >15 % of patients included fatigue and neutropenia. Maximum tolerated dose was tivozanib 1.5 mg with paclitaxel 90 mg/m(2). Four patients withdrew because of toxicity and one due to progressive disease. Thirteen patients were evaluable for response: four (30.8 %) had confirmed partial response; four had stable disease ≥6 months (30.8 %). PK data suggest no influence of paclitaxel on tivozanib concentrations. Tivozanib plus weekly paclitaxel was tolerable at all dose levels, supporting their combination at full dose. Activity in this small population was encouraging.

Abstract OT2-3-11: Tivozanib in combination with paclitaxel vs placebo with paclitaxel in patients with locally advanced or metastatic triple-negative breast cancer

Background: Triple-negative breast cancer (TNBC) is an aggressive cancer with inferior survival outcomes. Although weekly paclitaxel (WP) is effective in the treatment (tx) of metastatic breast cancer (MBC), optimization of therapies for patients (pts) with TNBC is essential. Angiogenesis is a hallmark of advanced cancer, with subset analyses suggesting activity of angiogenesis inhibitors in TNBC. Tivozanib (TIVO) is a potent and selective inhibitor of vascular endothelial growth factor receptors (VEGFR) 1, 2, and 3 with a promising role in metastatic renal cell carcinoma, and established safety in Phase I combination with WP in MBC.

Purpose: This Phase II trial will assess the efficacy and safety of TIVO + WP in the first-line setting for pts with advanced or metastatic TNBC and evaluate the performance of candidate angiogenesis biomarkers.

Objectives: The primary objective of this study is to compare progression-free survival (PFS) of pts treated with TIVO + WP vs pts treated with placebo (PB) + WP. Secondary objectives include objective response rate (ORR), overall survival (OS), safety and tolerability, quality of life, and correlative candidate biomarker endpoints. The pharmacokinetics of TIVO + WP also will be characterized.

Study Design and Methods: This multicenter, randomized, PB-controlled, two-arm study will enroll pts with metastatic or unresectable TNBC (evaluable per RECIST) and no prior systemic therapy. Pts must have confirmed available archival tumor tissue. Pts will be stratified by ECOG performance score and number of metastatic sites, then randomized to receive either oral TIVO 1.5 mg once daily for 3 weeks (wks) on/1 wk off and intravenous WP 90 mg/m2 for 3 wks on/1 wk off, or PB + WP. One cycle will be 4 wks; tx will continue until disease progression or unacceptable toxicity. Archival tumor tissue and blood samples will be evaluated for response biomarkers, including a hypoxia sensitivity gene signature, a myeloid resistance gene signature, and angiogenic ligands. All pts will be followed for survival until death. Adverse events will be monitored throughout the study. Pharmacokinetic samples will be collected during cycles 1 and 2. PAM-50–defined intrinsic molecular subtype populations also will be evaluated retrospectively.

Recruitment of 130 patients is planned, with an interim analysis after 80 pts to measure ORR (130 pts with a total of 82 investigator-assessed PFS events provides 80% power to detect statistically significant PFS differences between tx arms). Endpoint analyses will use the intent-to-treat population. The primary efficacy analysis will use investigator assessments of response and a two-sided 95% confidence interval for the hazard ratio produced using Cox proportional hazards regression models. OS will be compared using the log-rank test. Analyses of candidate biomarkers and determination of an optimal predictive cutoff for response also are planned. Trial enrollment will commence in fall 2012.

Conclusion: This study will determine whether TIVO, a selective and potent VEGFR inhibitor, combined with WP improves clinical outcomes in pts with TNBC, and whether clinical activity is associated with candidate angiogenesis biomarkers.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr OT2-3-11.

PD04-03: Sexual Dysfunction in Premenopausal Women with Breast Cancer: Prevalence and Severity

Background: Sexual dysfunction is reported after chemotherapy and endocrine therapies. However, the prevalence and severity of sexual dysfunction in premenopausal women undergoing therapy for both local and metastatic disease is not well defined. This study was performed in order to understand the impact of contemporary breast cancer treatment on the prevalence and severity of sexual health in premenopausal women.

Methods: We developed a survey that includes a previously validated questionnaire, the Female Sexual Function Index (FSFI), as well as an established measure of health-related quality of life (the EuroQol EQ-5D), and disease-specific items to characterize sexual dysfunction and its causes based on literature review and expert consultations. Anonymous administration of the surveys was conducted in outpatient clinic waiting areas of the Breast Cancer Center at Memorial Sloan-Kettering Cancer Center (MSKCC), under an IRB waiver of consent.

Results: 372 consecutively approached premenopausal women with breast cancer of any stage, undergoing treatment were each queried once. The mean age was 47. 87% reported current or past hormonal treatment, and 86% reported current or past chemotherapy (76% adjuvant; 24% for metastatic disease). Sexual dysfunction attributed to breast cancer or its treatment, defined as an FSFI score &lt;26, was reported by 75% of respondents with a mean score of 16.3. Among these women, 79% of patients considered their sexual symptoms to be bothersome, with 51% noting moderate or severe levels of bother (score &gt;=5/10). In a multivariate analysis, metastatic disease, development of amenorrhea from cancer treatment, antidepressant use and poorer overall health were each significantly associated with worse FSFI scores. Lower FSFI scores were also significantly associated with worse health-related quality of life.

Conclusion: Sexual dysfunction is prevalent in premenopausal women treated for breast cancer and should be discussed with patients as a potential adverse effect of therapy. Assessment of sexual symptoms throughout treatment and beyond may facilitate the use of potential interventions such as lubricants, dilators, treatment modification and counseling.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr PD04-03.

P2-08-01: Impact of Aromatase Inhibitors on Background Parenchymal Enhancement and Amount of Fibroglandular Tissue on Breast MRI

Background: On breast MRI, background parenchymal enhancement (BPE) and volume of fibroglandular tissue (FGT) have been shown to reflect a patient's hormonal status. Tamoxifen has been shown to reduce mammographic breast density and may serve as an early predictor of response in the prevention setting (Cuzick, JNCI 2011). We have shown that adjuvant tamoxifen can reduce BPE in the unaffected breast in women with breast cancer. We hypothesize that aromatase inhibitor (AI) induced endocrine changes in breast tissue should also be evident and therefore we performed a study to evaluate whether adjuvant AI therapy influences BPE or amount of FGT in the contralateral breast.

Methods: An electronic medical record review identified 856 postmenopausal women with stage I-III breast cancer who had at least two breast MRIs and took adjuvant AI treatment. A retrospective chart review was conducted to select those patients without a history of prior tamoxifen or raloxifene treatment who had a MRI of the contralateral breast both before and during 6 to 12 months of AI treatment. After exclusion of all irradiated breasts, 168 women were eligible. MRIs were performed between August 1999 and June 2010. Two radiologists who were blind to AI treatment status, independently rated level of BPE and amount of FGT using categorical scales: BPE — Minimal, Mild, Moderate, Marked; FGT — Fatty, Scattered, Heterogeneously Dense, Dense (based on proposed BIRADS criteria for BPE and on ACR criteria for FGT). Blinded side-by-side direct comparison evaluated whether there was a category change between the two MRIs. A consensus was reached in cases of disagreement. The Wilcoxon signed-rank test was used to assess changes in rating categories for BPE and FGT between before and during AI breast MRIs. A waiver of authorization was granted by the institutional review board for this study.

Results: In this study 127/168 (76%) women were treated with anastrozole, 33/168 (20%) with letrozole and 8/168 (5%) with exemestane. Based on the blinded side-by-side comparison, a category (or more) decrease in BPE occurred during treatment with AIs (p&lt;0.0001). There was an overall shift from higher to lower degree of BPE in 35% (45/127) of the women taking anastrozole while a category increase occurred in only one woman (1%; p &lt;0.0001). A similar result was seen in the women taking letrozole [45% (15/33) had a decrease versus 3% (1/33) an increase; p=0.0003] and exemestane [25% (2/8) had a decrease versus 12.5% (1/8) an increase; p=0.50]. For FGT a category decrease occurred in 5% (6/127) of anastrozole users while no increase occurred [0% (0/127), p=0.016]. The respective numbers for letrozole were 3% (1/33) and 0% (0/33), and nobody on exemestane had a change in FGT.

Conclusions: After 6 to 12 months of treatment with adjuvant AIs, there was a statistically significant category (or more) decrease in BPE. BPE is more sensitive than FGT to changes in normal breast stroma that occur during adjuvant treatment with AIs and BPE may be a marker of anti-hormonal activity in the breasts.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P2-08-01.

OT3-02-04: TBCRC 012: ABCDE, a Phase II Randomized Study of Adjuvant Bevacizumab, Metronomic Chemotherapy (CM), Diet and Exercise after Preoperative Chemotherapy for Breast Cancer

Background Patients (pts) with residual breast cancer after neoadjuvant chemotherapy are at increased risk of recurrence; no proven risk-reduction strategies exist, supporting exploration of novel therapies in the post-preoperative setting. Bevacizumab (B) combined with chemotherapy is active in metastatic disease; ongoing studies are exploring the efficacy of adjuvant combination chemotherapy and B. DFCI 05–055 (Mayer et al, ASCO 2007, 2008) demonstrated the feasibility of 1 year B after preoperative chemotherapy. Also, increasing data support risk reduction through lifestyle interventions (Segal, Ligibel et al, ASCO 2011). The ABCDE trial was designed to evaluate extended adjuvant B in a high risk post-preoperative cohort, and also assess the contribution of exercise to a dietary intervention.

Eligibility Criteria Eligible pts have HER2− breast cancer and have received preoperative anthracycline and/or taxane-based chemotherapy with residual invasive disease at surgery. Acceptable stages include: triple negative if preop stages I-III, or ER+/PR+ if stage III preop or IIB postop. Acceptable organ function and standard B exclusions apply. Registration must occur between 28–180 days after last surgery.

Specific Aims Primary endpoint is recurrence-free survival at a median follow-up of 6 years. Secondary endpoints include B pharmacogenomics, evaluation of the impact of exercise on quality of life and biomarkers associated with recurrence, and prospective examination of cardiac toxicity. Residual tissue-based predictors of outcome will be extensively explored, including PAM50, Ki67, and VEGF hypoxia signature.

Methods This is a 2 × 2 randomized study with a first randomization to 6 months (mo) B 15 mg/kg every 3 weeks (wks) plus 6 mo CM (C 50 mg daily, M 2.5 mg twice daily days 1, 2 each wk), followed by 2.5 years B 15 mg/kg every 6–8 wks, versus observation. A second randomization is to a 1 year telephone-based lifestyle intervention, offering dietary modification alone, or in combination with a structured exercise program.

Statistical Methods and Accrual Total sample size is 660 pts within the Translational Breast Cancer Research Consortium. Overall power is 0.80 to detect a hazard ratio of 0.59−0.68, depending on pt population. Accrual initiated early 2011 and is expected to continue for the next 36 months.

Conclusions Patients with residual disease after preoperative chemotherapy are at high risk of recurrence and have unmet medical needs. To our knowledge, this is the only trial testing a prolonged but less intensive adjuvant B schedule in this clinical setting. Results of this study could have critical implications for the management of this patient population and for the design of future clinical trials with anti-angiogenic agents.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr OT3-02-04.

A phase I study of dasatinib and weekly paclitaxel for metastatic breast cancer

BACKGROUND

SRC plays an important role in the pathogenesis of metastatic breast cancer (MBC). In preclinical models, paclitaxel and the oral SRC inhibitor dasatinib showed greater antitumor activity than either agent. To determine the maximum tolerated dose of this combination, we conducted a phase I study.

PATIENTS AND METHODS

Patients with MBC; Eastern Cooperative Oncology Group performance status of zero to one; normal hepatic, renal and marrow function were eligible. Paclitaxel 80 mg/m(2) was given 3 weeks of 4. The starting dasatinib dose was 70 mg and was increased, using a standard 3 + 3 dose-escalation scheme.

RESULTS

Fifteen patients enrolled (median age 54 years, range 35-74). No dose-limiting toxic effects (DLTs) occurred at dasatinib doses of 70-120 mg. One DLT (grade 3 fatigue) occurred in the dasatinib 150-mg cohort, which was expanded (six patients) with no further DLTs. However, due to cumulative toxic effects (rash, fatigue, diarrhea), the recommended phase II dose is dasatinib 120 mg. Of 13 assessable patients, a partial response was seen in 4 patients (31%), including 2 patients previously treated with taxanes; all received ≥120 mg dasatinib. An additional five patients (29%) had stable disease.

CONCLUSION

In combination with weekly paclitaxel, the recommended phase II dose of dasatinib is 120 mg daily and preliminary activity has been seen in patients with MBC.

Abstract P6-12-09: A Phase I-II Trial of Dasatinib (D) in Combination with Weekly (w) Paclitaxel (P) for Patients (Pts) with Metastatic Breast Carcinoma (MBC)

Background: Inhibition of SRC is a novel approach for MBC. D is an inhibitor of multiple tyrosine kinases, including the SRC family. Pre-clinical data show D inhibits multiple breast cancer cell lines, including those of “basal-like” subtype. In preclinical models D + P had superior antitumor activity to either agent alone. We designed this phase I-II study to translate this observation.

Methods: For phase I: pts with MBC, ECOG PS 0-1, normal hepatic, renal, marrow function were eligible. Pts with pleural/pericardial effusions were excluded. For phase II: pts had measurable, HER2-negative MBC, ≥2 prior rx for MBC. Prior taxanes, stable brain metastases and baseline neuropathy grade ≥1 were allowed. Cycle (C) consisted of wP 80 mg/m2 IV 3/4 weeks + D 70mg orally daily; escalating to 100 mg, 120 mg and 150 mg in cohorts of 3pts. Toxicity was assessed by CTCAE v3.0, response by RECIST.

Results: 17 pts enrolled (15 phase I; 2 phase II); median age 54 (range 35-74), median PS=1 (range 0-1). 12 (71%) pts rcvd prior adjuvant chemoRx. Pts rcvd a median of 3 prior rx for MBC (range 0-12). Pts rcvd median of 2 C of D + P (range 1-14). One DLT occurred at 150mg (G3 fatigue); this cohort was expanded with no further DLTs. However 3 pts on this dose level withdrew;1 pt delayed hypersensitivity rash (grade 1), 1 pt febrile neutropenia (grade 3), 1 pt paclitaxel pneumonitis (grade 3). Therefore the phase II dose is D 120mg. Overall the most common toxicities have been hematologic and low G (table). 13 pts are assessable for response; 4 patients (31%) had a PR, including 3 patients previously treated with taxanes. 5 pts (29%) had stable disease.

Toxicities &gt; Grade 1

Conclusion: Treatment with wP and D is feasible in pts with MBC. In the phase I study, 1 DLT occurred at D 150mg but due to cumulative toxicities the recommended dose for the ongoing phase II study is 120mg. Preliminary evidence of activity has been seen in taxane-pretreated pts at the phase II dose. Identification of biomarkers to select appropriate pts for this therapeutic approach is the subject of ongoing correlative studies.

Abstract P2-16-08: Administration of the Novel Antiangiogenic PTC299 in Combination with Aromatase Inhibitors Is Feasible and Shows Antitumor Activity in Metastatic Breast Cancer

Background: PTC299 is an investigational new drug that suppresses tumor growth by selective post-transcriptional inhibition of tumor VEGF expression. PTC299 demonstrates antitumor activity in both hormone-receptor-positive (HR+) and-negative (HR-) breast cancer xenograft models and eliminates established tumors in aromatase-overexpressing human breast cancer xenografts when given alone or in combination with letrozole.

Methods: This study is assessing the feasibility of PTC299 administration in combination with aromatase inhibitors (AIs) in women with HR+ metastatic breast cancer and natural or induced post-menopausal levels of ovarian function. Patients already receiving or newly initiating a standard dose of an AI are coadministered 100 mg BID of oral PTC299 continuously until disease progression.

Results: To date, the study has enrolled 24 women with a median [range] age of 57 [26-82] years, ECOG PS of 0 (n=12) or 1 (n=12), to receive PTC299 together with letrozole (n=11), anastrozole (n=6), or exemestane (n=7) for a median [range] duration of ∼16 [3-36] weeks. Combination therapy has been generally well tolerated; AEs have been predominantly Grade 1-2, have usually not been PTC299-related. The most frequent AEs have been headache (25%) and hot flashes (25%). No PTC299 dose reductions or discontinuations due to AEs have occurred. Measures of PTC299 plasma exposure have shown ∼2-fold accumulation, with values reaching steady state by -21 days of treatment; trough values have exceeded those maximally active in xenograft models. Relative to baseline, therapy has been associated with on-study reductions in circulating VEGF concentrations and decreases in tumor perfusion as assessed by DCE-MRI. Antitumor activity includes 3 CRs by PET/CT, 1 PR by PET/CT, and 3 PRs by PET scan. To date, 7/24 (29%) patients have received ≥24 weeks of treatment and 10/24 (42%) patients continue on treatment.

Conclusions: Combining PTC299 100 mg BID with standard AI treatment appears feasible. Safety, exposure, pharmacodynamic, and antitumor activity observations have been encouraging. Supported by a grant award from the Department of Defense

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P2-16-08.

Abstract P5-08-01: Oncology Clinicians’ Knowledge, Attitudes and Practices Regarding Fertility Preservation

Background:

Many breast cancer survivors of child-bearing age wish to become parents after therapy and are concerned about the possibility of treatment-induced infertility. Educating patients about the effects of therapy on fertility, early menopause, and fertility preservation options prior to treatment may optimize a survivor's quality of life after treatment. It is unclear whether oncologists feel qualified to discuss fertility issues with their patients, and if not, what barriers prevent such discussions.

Methods:

An IRB approved cross-sectional survey was developed at Memorial Sloan-Kettering Cancer Center (MSKCC) in order for clinicians to self-evaluate their knowledge, attitudes, and behaviors regarding fertility preservation. Survey items were derived from existing surveys in the literature and input from a multidisciplinary committee. The web-based survey was systematically administered to all MSKCC ambulatory clinicians. Repeated email reminders were sent to optimize responses.

Results:

76 breast cancer clinicians at MSKCC and our regional network sites completed the survey between 2/9/09 and 2/25/09. Among respondents, there was widespread agreement (97% (70/72)) that patients should be informed of fertility preservation options, but fewer respondents (51% (37/72)) consistently discussed effects of treatment on fertility with their patients. Only 47% of clinicians (35/74) reported access to information about effects of treatment on fertility. Many physicians cited lack of training in fertility preservation, time constraints, and lack of referral information as barriers to educating patients. No significant difference existed in practice or knowledge between physicians who were practicing for ≤ 5 years vs ≥ 5 years.

Conclusions:

Physicians report that lack of education, resources and insufficient time hinder fertility preservation discussions with patients. Physicians might benefit from educational efforts regarding the effects of treatment on fertility and new fertility preservation techniques in order to effectively counsel their patients. Time limitations may be overcome by developing educational resources and collaborating with other clinical staff (e.g., nurses) to provide this vital information to patients. These findings are informing an institution-wide educational fertility program.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P5-08-01.

Burden of Sexual Dysfunction in Women with Breast Cancer

Background: Sexual dysfunction is reported after chemotherapy and endocrine therapies, and causes a substantial burden on women with breast cancer. However, the prevalence and severity of sexual dysfunction in women undergoing therapy for both local and metastatic disease is not well defined. Improved understanding of sexual dysfunction may facilitate enhanced treatment and interventions in patients with breast cancer undergoing active treatment, and in survivors of this disease.Methods: We developed a survey that includes a previously validated questionnaire, the female sexual function index (FSFI), as well as an established measure of health-related quality of life (the EuroQol EQ-5D), and disease-specific items to characterize sexual dysfunction and its causes based on literature review and expert consultations. Anonymous administration of the surveys was conducted in outpatient clinic waiting areas of the Breast Cancer Center at Memorial Sloan-Kettering Cancer Center (MSKCC) and two community centers, under an IRB waiver of consent.Results: During November 2008 through May 2009, 509 women undergoing treatment for breast cancer of all stages were each queried once. The mean age was 51 (range 26-91). 87% reported current or past hormonal treatment, and 82% reported current or past chemotherapy (76% adjuvant; 24% for metastatic disease). Sexual dysfunction attributed to breast cancer or its treatment, defined as an FSFI score &lt;26, was reported by 76% of respondents. Among these women, 316/386 (82%) patients considered their sexual symptoms to be bothersome, with 247/386 (64%) noting moderate or severe levels of bother (score &gt;=5/10). Patients attributed their sexual dysfunction to chemotherapy in 318/373 (85%) of cases; to hormonal therapy in 221/298 (74%) of cases; and to surgery in 331/442 (66%) of cases. Other reported contributors to sexual dysfunction include a new diagnosis of breast cancer by 81% of respondents, anxiety by 82% of respondents, and change in relationship with a partner by 55% of respondents.Conclusion: Sexual dysfunction is prevalent in women treated for breast cancer and should be discussed with patients as a potential adverse effect of therapy. Assessment of sexual symptoms throughout treatment and beyond may facilitate the use of potential interventions such as lubricants, dilators, treatment modification, topical estrogens, and counseling. Future work includes a longitudinal prospective trial to further characterize the etiologies of these symptoms and a randomized controlled trial to evaluate interventions for sexual dysfunction.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 1056.

Sexual dysfunction in women with breast cancer: Prevalence and severity

9558

Background: Sexual dysfunction (SD) is reported after chemotherapy and endocrine therapies, and causes a substantial burden on women with breast cancer. However, the prevalence and severity of SD in this population is not well defined. Improved understanding of SD may allow for enhanced treatment and interventions in patients with breast cancer undergoing active treatment, and in survivors of this disease. Methods: We developed a survey that includes a previously validated questionnaire, the female sexual function index (FSFI), and disease-specific items to characterize SD and its causes based on literature review and expert consultations. Anonymous administration of the surveys was conducted in outpatient clinic waiting areas of the M64/Breast Center Memorial Sloan-Kettering Cancer Center (MSKCC), under an IRB waiver of consent. Results: During November-December 2008, 100 women with breast cancer of any stage were each queried once. The mean age was 52 (range 26–75). 68% reported current or past hormonal treatment, and 63% reported current or past chemotherapy (84% adjuvant; 16% for metastatic disease). SD attributed to breast cancer or its treatment, defined as an FSFI score <26, was reported by 75% of respondents. Among these women, severe symptoms were noted by 38/75 (51%), and moderate by 37/75 (49%). 87/95 (92%) patients considered their sexual symptoms to be bothersome, with 59/95 (62%) noting moderate or severe levels of bother (score >=5/10). Patients attributed their SD to chemotherapy in 52/63 (83%) of cases; to hormonal therapy in 56/68 (82%) of cases; and to surgery in 68/92 (74%) of cases. Other contributors to SD were felt to include anxiety by 83% of respondents, and change in relationship with a partner by 46%. Conclusions: SD is prevalent in women treated for breast cancer and should be discussed with patients as a potential adverse effect of therapy. Assessment of sexual symptoms throughout treatment and beyond may facilitate the use of potential interventions such as lubricants, dilators, treatment modification, topical estrogens, and counseling. A longitudinal prospective trial is planned to further characterize the etiologies of these symptoms.

No significant financial relationships to disclose.

Bone scintigraphy (BS) may no longer be relevant in the era of integrated PET/CT for women undergoing evaluation for suspected metastatic breast cancer (MBC)

Abstract #5007

Background: &#x2028; The accurate detection of osseous metastases frequently has significant prognostic and therapeutic implications at metastatic breast cancer (MBC) diagnosis. However, the ideal paradigm for accurate detection of osseous metastases has not yet been determined. In this retrospective, single-institution study, we compare the diagnostic performance of integrated positron emission tomography/computed tomography (PET/CT) versus bone scintigraphy (BS) for women undergoing extent-of-disease (EOD) evaluation for suspected MBC.&#x2028; Methods:&#x2028; Women undergoing EOD evaluation for suspected MBC with integrated PET/CT and bone scintigraphy (BS) between January 1, 2005 and Dec 31, 2007 were identified through institutional databases. Patients with PET/CT and BS imaging completed within 30-days of each other were included. Women with a prior history of MBC or an active second malignancy were excluded. Electronic medical record (EMR) reports were reviewed and classified as positive, negative or equivocal for detecting osseous metastases. All EMR reports deemed potentially equivocal were reviewed by 2 investigators and consensus reached regarding the final classification. Bone biopsy data, where available, was also recorded.&#x2028; Results:&#x2028; The median age of the 62 eligible women was 54y (33-90y). Overall, PET/CT and BS demonstrated a high degree of concordance. Of the 41 concordant studies, 13 (21%) and 28 (45%) were reported as positive and negative for osseous metastases, respectively. No studies were classified as equivocal by both modalities. Ten positive PET/CT studies were negative by BS, but no PET/CT-negative studies were positive by BS. Of the 10 patients with PET/CT-positive, BS-negative studies, 4 had subsequent bone biopsies, all of which confirmed osseous metastases.&#x2028; &#x2028; Conclusions:&#x2028; This study supports the diagnostic performance of integrated PET/CT in detecting osseous metastases when EOD evaluation for suspected MBC is considered. Whether PET/CT may supplant BS entirely in this setting has not yet been determined.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 5007.

Circulating tumor cell and endothelial cell data from a phase II evaluation of lapatinib and bevacizumab in HER2-overexpressing metastatic breast cancer

Abstract #3154

Background: Overexpression of both HER2 and VEGF is associated with worse outcome than overexpression of either receptor alone. In preclinical models, combination anti-HER2 and anti-VEGF therapy has been shown to be more effective than either treatment alone. Bevacizumab (B) plus trastuzumab and lapatinib (L) plus pazopanib have shown activity in patients (pts) with HER2+ MBC. We evaluated the combination of L+B in a phase 2 trial in HER2+ MBC pts. To explore new biomarkers of treatment effect, we measured circulating tumor cells (CTCs) with two different methods of CTC enumeration: CellSearch (Veridex LLC), and immunomagnetic enrichment followed by flow cytometry (IE/FC), as well as circulating endothelial cells (CECs) in pts receiving study treatment.&#x2028; Methods: This study evaluated L (1500 mg PO daily) plus B (10 mg/kg IV q2wk) in 50 HER2+ MBC pts. The primary endpoint is crude progression-free survival (PFS) at 12 wks. Serial evaluation of CTC and CEC was performed. Blood was obtained from consenting pts at baseline, weeks 2, 6 then every 12 weeks until end of study. CellSearch assay was performed as previously described using 7.5 cc blood in a CellSave tube and the CellSpotter analyzer. For IE/FC, 20 ml of blood was subjected to IE using anti-EpCAM ferrofluid, followed by FC for EpCAM, CD45, and nucleic acid content. CTC data were correlated with assay method and with best response. CECs were defined as CD34/31+, CD45-, or CD34/146+, CD45-, and were assayed by FC.&#x2028; Results: Enrollment to this study ended in March 2008 (n=52). Clinical data is presented at this meeting (Dickler et al). 47 patients have evaluable CTC and CEC data at baseline and/or first follow-up; 32 patients have response data. CTC determined by CellSearch or IE/FC showed significant correlation at baseline (R=0.58; P=0.012). CTC by CellSearch at first followup correlated with treatment response (P=0.01) with levels above 5 CTC/sample associated with progression; there was no correlation with baseline values. There were too few positive IE/FC values to evaluate correlation with outcome. The change in CEC/CD146 from baseline to first followup for is of borderline significance in this preliminary analysis (P=0.07) between PR (N=2, Mean Change Score/MCS=-4.345) and SD/PD (N=18, MCS=0.8); a decrease of CEC/CD146 from baseline to first followup suggests greater likelihood of response.&#x2028; Conclusions: L+B is an active regimen in pts with MBC. CTC measurements correlated between two separate methodologies, and for the CellSearch assay predicted response to therapy. A decrease in CEC from baseline to first followup correlated with response to this combined targeted therapy, consistent with our previous results with other B-based therapy. PFS and response correlations for the full study cohort will be presented.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 3154.

Dose-dense (DD) doxorubicin and cyclophosphamide (AC) followed by weekly paclitaxel (P) with trastuzumab (T) and lapatinib (L) in HER2/neu-positive breast cancer is not feasible due to excessive diarrhea: updated results

Abstract #2108

Background: DD q 2 weekly (w) AC → P + T x 1 year (y) has an acceptable safely profile w/ congestive heart failure (CHF) rate of 1/70 pts (Dang, JCO 2008). Lapatinib (L) is effective in HER2 (+) BC. We conducted a pilot study of dd AC → w P + T + L to determine its feasibility and cardiac safety.&#x2028; Methods: Enrolled pts had HER2 (+) BC; LVEF &gt; 50%. Rx consisted of AC at 60/600 mg/m2 x 4 q 2 w (w/ pegfilgrastim 6 mg day 2) → P at 80 mg/m2 x 12 q w + T x 1 y; L (1000 mg daily beginning w/ P + T and continued x 1 y). MUGA is obtained at baseline and at months (mo) 2, 6, 9, and 18. Rx is considered feasible if 1) &gt; 80% pts can complete the PTL phase without a dose delay or reduction and 2) the cardiac event rate (CHF or cardiac death) is &lt; 4%. Pts can remain on-Rx w/ one dose reduction of L (1000 mg → 750 mg) for a G 3 event or &lt; G 3 toxicity (unacceptable).&#x2028; Results: From March 2007 to April 2008, we enrolled 95 pts. Median (med) age was 45 years (range, 28-73). At a med follow-up of 7 months, 90 are evaluable. Of the 90 pts, 34 (37%) withdrew from study during the PTL phase; 29 for a 2nd event of G 3 or unacceptable &lt; G 3 toxicities (15 G 3 diarrhea, 4 G 1/2 diarrhea, 1 G 3 rash, 2 G 2 rash, 1 G 3 dyspnea and also had G 3 diarrhea, 1 G 3 ↑QTc also had G 3 diarrhea, 1 G 3 ↑ALT also had G 3 diarrhea, 1 G 3 paronychia, 1 G 3 pneumonitis, 1 asymptomatic LVEF ↓, 1 myocarditis) and 5 for other reasons (2 personal reason, 1 PCP pneumonia, 1 progression, 1 P hypersensitivity). Overall, 25/90 (27%) pts had G 3 diarrhea and 31/90 (34%) pts required a dose reduction of lapatinib. Med LVEF at baseline is 67% (N=95), at mo 2 is 68% (N=90), at mo 6 is 65% (N=53), and mo 9 is 65% (N=28). To date there are no patient drop-outs due to significant LVEF declines after dd AC; one patient dropped during PTL out due to an asymptomatic LVEF decline.&#x2028; Discussion: L at 1000 mg/day is not feasible combined w/ weekly P and T by protocol stipulation (&gt; 20% pts required L dose reduction) primarily due to excessive G 3 diarrhea. These results have led to the modification of Design 2 (Arm D) of ALTTO. We will report updated results.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 2108.

Pharmacokinetics and tolerability of exemestane in combination with raloxifene in postmenopausal women with a history of breast cancer

PURPOSE

Raloxifene is a second-generation selective estrogen receptor modulator that reduces the incidence of breast cancer in postmenopausal women. Exemestane, a steroidal aromatase inhibitor, decreases contralateral new breast cancers in postmenopausal women when taken in the adjuvant setting. Preclinical evidence suggests a rationale for coadministration of these agents to achieve complete estrogen blockade.

EXPERIMENTAL DESIGN

We tested the safety and tolerability of combination exemestane and raloxifene in 11 postmenopausal women with a history of hormone receptor-negative breast cancer. Patients were randomized to either raloxifene (60 mg PO daily) or exemestane (25 mg PO daily) for 2 weeks. Patients then initiated combination therapy at the same dose levels for a minimum of 1 year. Pharmacokinetic and pharmacodynamic data for plasma estrogens, raloxifene, exemestane, and their metabolites were collected at the end of single-agent therapy and during combination therapy.

RESULTS

Plasma concentration-time profiles for each drug were unchanged with monotherapy versus combination therapy. Raloxifene did not affect plasma estrogen levels. Plasma estrogen concentrations were suppressed below the lower limit of detection by exemestane as monotherapy and when administered in combination with raloxifene. The most common adverse events of any grade included arthralgias, hot flashes, vaginal dryness and myalgias.

CONCLUSIONS

In this small study, coadministration of raloxifene and exemestane did not affect the pharmacokinetics or pharmacodynamics of either agent to a significant degree in postmenopausal women. The combination of estrogen receptor blockade and suppression of estrogen synthesis is well tolerated and warrants further investigation.

Phase II study of weekly nanoparticle paclitaxel (ABI-007), carboplatin and trastuzumab as first-line therapy of HER2-positive metastatic breast cancer

10650

Background: The combination of carboplatin (C), paclitaxel (P) and trastuzumab (T) is active in HER2+ metastatic breast cancer (MBC) (Robert N et al. Proc ASCO 2003), and safer with weekly administration of all 3 agents (Perez E et al. Proc ASCO 2004). The superiority of nanoparticle paclitaxel (Abraxane, AB) over Cremophor-based paclitaxel (Gradishar W et al. JCO 2005), and the efficacy and safety of weekly AB in MBC (Blum J et al. Proc ASCO 2005) motivated us to conduct this study. Materials/Methods: To date 10 of 50 planned patients (pts) with measurable, HER2+ MBC have entered. After we established the safety of AB at 75 mg/m2 on days 1, 8, and 15 every 28 days (n = 4 pts), all subsequent pts received AB at 100 mg/m2. C was dosed at AUC = 2 on the same schedule, and T was weekly at 2 mg/kg without interruption, after a 4 mg/kg load. Initially, no prophylactic anti-allergy medication was given. Treatment is until disease progression (PD) or prohibitive toxicity. Pts without PD at 6 months may opt to continue T alone. Median age: 42 yrs (29–66), ECOG PS 0/1 (70/30%); 6 pts had prior adjuvant chemotherapy; 1 with anthracycline (A) and 4 with A + taxane (> 1 yr prior). Results: 68 cycles have been delivered to date (median: 8, range 1–9). Dose reductions of AB and C have been necessary in 4 pts (to 80 mg/m2 and AUC of 1.5 weekly), with delays in 4 pts. 3 pts had hypersensitivity reactions (HSR) to C and continued protocol therapy without C (n = 2) or with C and the addition of anti-HSR premeds (n = 1). Grade ¾ toxicities include neutropenia (44/11%) with 1 episode of febrile neutropenia. Grade ¾ anemia or thrombocytopenia has not occurred. Grade ¾ non-hematologic toxicity has been rare: 1 instance of grade 3 neuropathy (2 pts with grade 2). 7 partial responses have been observed in the first 9 evaluable pts (78%, 95% CI 44–93%), in liver, lung, bone and soft tissue sites, including 4 pts with prior adjuvant taxane. The median time to PD is not reached at 9.9+ months (7.3–9.9+). Accrual continues as the trial expands to additional study sites. Conclusions: The weekly administration of AB, C, and T demonstrates promising preliminary efficacy as 1st-line treatment for HER2+ MBC. With the exception of HSRs due to weekly C, a very favorable toxicity profile is observed.

[Table: see text]

Letrozole (L) with bevacizumab (B) is feasible in patients (pts) with hormone receptor-positive metastatic breast cancer (MBC)

3050

Background: Bevacizumab added to chemotherapy (CRx) prolongs PFS in pts with MBC. Data suggest that estrogen (E2) modulates VEGF-induced angiogenesis in physiologic and pathologic conditions. E2-induced VEGF expression may promote breast cancer growth therefore combination therapy with an aromatase inhibitor (AI) and an antibody to VEGF may be more effective than either agent alone. We performed a feasibility study testing B with L for the treatment (tx) of hormone receptor-positive MBC. Methods: Eligible pts have MBC and are candidates for AI therapy. Prior non-steroidal AI (NSAI) use without progression is permitted. Premenopausal pts undergo ovarian suppression/oophorectomy prior to tx. Therapy consists of L (2.5 mg daily) and B (15 mg/kg IV q3 weeks). The primary endpoint is frequency of Grade (Gr) 4 toxicity. Secondary endpoints include response rate, stable disease (SD) ≥ 6 mo and time to tumor progression. Using a two-stage design, 19 pts were accrued. Because <3 pts had Gr 4 toxicity, the 2nd stage is now enrolling an additional 23 pts. If <5 of the 42 pts have Gr 4 toxicity, the regimen will be considered feasible. Results: Thirty two pts are currently accrued and 28 are now evaluable. Medians: Age 49.5 yrs (32–77) and ECOG PS 0 (0–1). Sites of MBC: bone only 11/28, visceral 16/28, chest wall/soft tissue/lymph nodes 11/28. All are ER and/or PR (+); none are HER2 (+). Prior therapy: adjuvant CRx 20; adjuvant tamoxifen 14. Twenty five pts received an NSAI as first-line tx of MBC, starting a median of 23 wks (1–213) before B. Three pts received first-line tamoxifen; one pt had prior CRx for MBC. After a median of 8 cycles (1–20), tx-related toxicities: Gr 2: hypertension (HTN) 4, headache (HA) 4, proteinuria 3, fatigue 6, joint pain 5, hot flashes 1, epistaxis 1; Gr 3: HTN 5, HA 1, proteinuria 1. There has been no tx-related Gr 4/5 toxicity. Tx-related withdrawals: HTN 1 and headache 1. Twenty five pts are evaluable for response: PR 2, SD ≥ 6 mo 13, SD 4, progression 6. Conclusions: Combination L and B is well tolerated and will be studied in a randomized CALGB trial. Circulating endothelial and tumor cell data is reported separately. Supported in part by Genentech and Novartis.

[Table: see text]

Occult central nervous system involvement in patients with metastatic breast cancer: prevalence, predictive factors and impact on overall survival

BACKGROUND

As screening central nervous system (CNS) imaging is not routinely performed, the incidence and clinical relevance of occult CNS metastases in advanced breast cancer is unknown.

PATIENTS AND METHODS

All patients screened for participation in one of four clinical trials were included; each of the trials excluded patients with known CNS involvement and required screening CNS imaging. A cohort of breast cancer patients with symptomatic CNS metastases was identified from the IU Cancer Center Tumor Registry for comparison.

RESULTS

From November 1998 to August 2001, 155 screening imaging studies were performed. Twenty-three patients (14.8%) had occult CNS metastases. HER-2 overexpression (P = 0.02) and number of metastatic sites (P = 0.03) were predictive of CNS involvement by multivariate analysis. Median survival from time of metastasis (1.78 versus 2.76 years; P <0.0001) and from screening (4.67 versus 10.4 months; P = 0.0013) was shorter in patients with than without occult CNS metastasis. Survival among patients with occult CNS metastasis was similar to patients with symptomatic CNS disease.

CONCLUSIONS

Patients with CNS involvement, whether occult or symptomatic, have an impaired survival. Occult CNS metastasis is relatively common, but impact on survival of treating occult CNS disease in patients with progressive systemic metastases is questionable.

The MORE trial: multiple outcomes for raloxifene evaluation--breast cancer as a secondary end point: implications for prevention

Breast cancer is a common disease in the United States and Europe and is therefore a major target for prevention strategies. Estrogen plays a central role in its pathogenesis, and treatment with estrogen deprivation has long been recognized to be an effective therapy. Tamoxifen is the first selective estrogen receptor modulator (SERM) to be widely used for the treatment of breast cancer and has been demonstrated to reduce the risk of breast cancer in high-risk women. Raloxifene is a second-generation SERM that has estrogenic effects on bone and lipid metabolism, and antiestrogenic effects on breast tissue. Unlike tamoxifen, raloxifene displays antiestrogenic effects on the endometrium and may serve as a safer alternative to tamoxifen in the prevention setting. The MORE trial is a multicenter randomized placebo-controlled trial designed to determine whether 3 years of raloxifene reduces the risk of fracture in postmenopausal women with osteoporosis. As a secondary end point of the trial, raloxifene was shown to reduce the risk of both in situ and invasive breast cancer by 65% (RR = 0.35; 95% CI = 0.21-0.58; P < 0.001). The benefits were most significant in women who developed estrogen receptor (ER)-positive cancers, with a relative risk of 0.10 (95% CI = 0.04-0.24). This reduced incidence of breast cancer may be due to an anticarcinogenic effect or to a slowing of growth of occult ER-positive cancer, with a shift to the right in the time-to-cancer curve. A second large-scale prevention trial in breast cancer comparing tamoxifen to raloxifene is presently enrolling cancer-free, but high-risk postmenopausal women (the STAR trial). Future directions include combined estrogen blockade of the breast by the addition of an aromatase inhibitor to a SERM. New trial designs, including those based on biochemical changes at the tissue level, will be required to allow future progress in this field with adequate rapidity.

Weekly trastuzumab and paclitaxel therapy for metastatic breast cancer with analysis of efficacy by HER2 immunophenotype and gene amplification

PURPOSE

This phase II study evaluated weekly trastuzumab and paclitaxel therapy in women with HER2-normal and HER2-overexpressing metastatic breast cancer. Efficacy was correlated with immunohistochemical and fluorescent in situ hybridization (FISH) assay results.

PATIENTS AND METHODS

Eligible patients had bidimensionally measurable metastatic breast cancer. Up to three prior chemotherapy regimens, including prior anthracycline and taxane therapy, were allowed. Trastuzumab 4 mg/kg and paclitaxel 90 mg/m2 were administered on week 1, with trastuzumab 2 mg/kg and paclitaxel 90 mg/m2 administered on subsequent weeks. HER2 status was evaluated using four different immunohistochemical assays and FISH.

RESULTS

Patients received a median of 25 weekly infusions (range, one to 85 infusions). Median delivered paclitaxel dose-intensity was 82 mg/m2/wk (range, 52 to 90 mg/m2/wk). The intent-to-treat response rate for all 95 patients enrolled was 56.8% (95% confidence interval, 47% to 67%). A response rate of 61.4% (4.5% complete response, 56.8% partial response) was observed in 88 fully assessable patients. In patients with HER2-overexpressing tumors, overall response rates ranged from 67% to 81% compared with 41% to 46% in patients with HER2-normal expression (ranges reflect the different assay methods used to assess HER2 status). Differences in response rates between patients with HER2-overexpressing tumors and those with normal HER2 expression were statistically significant for all assay methods, with CB11 and TAB250 antibodies and FISH having the strongest significance. Therapy was generally well tolerated, although three patients had serious cardiac complications.

CONCLUSION

Weekly trastuzumab and paclitaxel therapy is active in women with metastatic breast cancer. Therapy was relatively well tolerated; however, attention to cardiac function is necessary.

Immunogenicity of a fucosyl-GM1-keyhole limpet hemocyanin conjugate vaccine in patients with small cell lung cancer

Although small cell lung cancer (SCLC) is highly responsive to chemotherapy, relapses are common, and most patients die within 2 years of diagnosis. After initial therapy, standard treatment is observation alone. We have been investigating immunization against selected gangliosides as adjuvant therapy directed against residual and presumably resistant disease persisting after chemotherapy and irradiation. Previously, we reported that the presence of anti-GM2 ganglioside antibodies is associated with a prolonged disease-free survival in patients with melanoma, and that SCLC patients immunized with BEC2, an anti-idiotypic monoclonal antibody that mimics the ganglioside GD3, had a prolonged survival compared with historical controls. In the present trial, fucosyl-alpha1-2Galbeta1-3GalNAcbeta1-4(NeuAcalpha2-3) Galbeta1-4Glcbeta1-1Cer (Fuc-GM1), a ganglioside expressed on the SCLC cell surface, was selected as a target for active immunotherapy. Fuc-GM1 is present on most SCLCs but on few normal tissues. SCLC patients achieving a major response to initial therapy were vaccinated s.c. on weeks 1, 2, 3, 4, 8, and 16 with Fuc-GM1 (30 microg) conjugated to the carrier protein keyhole limpet hemocyanin and mixed with the adjuvant QS-21. Ten patients received at least five vaccinations and are evaluable for response. All patients demonstrated a serological response, with induction of both IgM and IgG antibodies against Fuc-GM1, despite prior treatment with chemotherapy with or without radiation. Posttreatment flow cytometry demonstrated binding of antibodies from patients' sera to tumor cells expressing Fuc-GM1. In the majority of cases, sera were also capable of complement-mediated cytotoxicity. Mild transient erythema and induration at injection sites were the only consistent toxicities. The Fuc-GM1-KLH + QS-21 vaccine is safe and immunogenic in patients with SCLC. Continued study of this and other ganglioside vaccines is ongoing.

Adjuvant therapy of malignant melanoma

The incidence of malignant melanoma continues to rise steadily in the United States, with approximately 40,300 new cases expected in 1997. A significant number of patients with deep primary lesions or regional lymph node metastases are at high risk for developing recurrent, metastatic disease despite adequate surgical intervention. Therefore, approaches to adjuvant therapy including immunotherapy, such as interferon, levamisole, and vaccines and chemotherapy and chemoimmunotherapy have been investigated in high-risk patients. The key adjuvant trials are reviewed, with emphasis placed on randomized trials. High-dose interferon-alpha has recently been shown to modestly improve disease-free and overall survival in a prospective randomized trial of high-risk patients and has been approved by the FDA for this indication. Vaccines, which currently remain experimental, may prove to be equally effective but less toxic options for adjuvant therapy. Also, the identification of more high-risk patients who might benefit from adjuvant therapy may be facilitated by sentinel lymph node biopsy and the reverse-transcriptase polymerase chain reaction for tyrosinase.

A deletion/insertion polymorphism in the human BCR gene on chromosome 22

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Heterogeneity of genomic fusion of BCR and ABL in Philadelphia chromosome-positive acute lymphoblastic leukemia

Philadelphia chromosome-positive acute lymphoblastic leukemia occurs in two molecular forms, those with and those without rearrangement of the breakpoint cluster region on chromosome 22. The molecular abnormality in the former group is similar to that found in chronic myelogenous leukemia. To characterize the abnormality in the breakpoint cluster region-unrearranged form, we have mapped a 9;22 translocation from the Philadelphia chromosome-positive acute lymphoblastic leukemia cell line SUP-B13 by using pulsed-field gel electrophoresis and have cloned the DNA at the translocation junctions. We demonstrate a BCR-ABL fusion gene on the Philadelphia chromosome. The breakpoint on chromosome 9 is within ABL between exons Ia and II, and the breakpoint on chromosome 22 is approximately equal to 50 kilobases upstream of a breakpoint cluster region in an intron of the BCR gene. This upstream BCR breakpoint leads to inclusion of fewer BCR sequences in the fusion gene, compared with the BCR-ABL fusion gene of chronic myelogenous leukemia. Consequently, the associated mRNA and protein are smaller. The exons from ABL are the same. Analysis of leukemic cells from four other patients with breakpoint cluster region-unrearranged Philadelphia chromosome-positive acute lymphoblastic leukemia revealed a rearrangement on chromosome 22 close to the breakpoint in SUP-B13 in only one patient. These data indicate that breakpoints do not cluster tightly in this region but are scattered, possibly in a large intron. Given the large size of BCR and the heterogeneity in breakpoint location, detection of BCR rearrangement by standard Southern blot analysis is difficult. Pulsed-field gel electrophoresis should allow detection at the DNA level in every patient and thus will permit clinical correlation of the breakpoint location with prognosis.