Adapting and implementing breast cancer follow-up in primary care: protocol for a mixed methods hybrid type 1 effectiveness-implementation cluster randomized study

BACKGROUND

Advances in detection and treatment for breast cancer have led to an increase in the number of individuals managing significant late and long-term treatment effects. Primary care has a role in caring for patients with a history of cancer, yet there is little guidance on how to effectively implement survivorship care evidence into primary care delivery.

METHODS

This protocol describes a multi-phase, mixed methods, stakeholder-driven research process that prioritizes actionable, evidence-based primary care improvements to enhance breast cancer survivorship care by integrating implementation and primary care transformation frameworks: the Exploration, Preparation, Implementation, and Sustainment (EPIS) framework and the Practice Change Model (PCM). Informed by depth interviews and a four round Delphi panel with diverse stakeholders from primary care and oncology, we will implement and evaluate an iterative clinical intervention in a hybrid type 1 effectiveness-implementation cluster randomized design in twenty-six primary care practices. Multi-component implementation strategies will include facilitation, audit and feedback, and learning collaboratives. Ongoing data collection and analysis will be performed to optimize adoption of the intervention. The primary clinical outcome to test effectiveness is comprehensive breast cancer follow-up care. Implementation will be assessed using mixed methods to explore how organizational and contextual variables affect adoption, implementation, and early sustainability for provision of follow-up care, symptom, and risk management activities at six- and 12-months post implementation.

DISCUSSION

Study findings are poised to inform development of scalable, high impact intervention processes to enhance long-term follow-up care for patients with a history of breast cancer in primary care. If successful, next steps would include working with a national primary care practice-based research network to implement a national dissemination study. Actionable activities and processes identified could also be applied to development of organizational and care delivery interventions for follow-up care for other cancer sites.

TRIAL REGISTRATION

Registered with ClinicalTrials.gov on June 2, 2022: NCT05400941.

Improving Uptake of Cancer Genetic Risk Assessment in a Remote Tailored Risk Communication and Navigation Intervention: Large Effect Size but Room to Grow

PURPOSE

Cancer genetic risk assessment (CGRA) is recommended for women with ovarian cancer or high-risk breast cancer, yet fewer than 30% receive recommended genetic services, with the lowest rates among underserved populations. We hypothesized that compared with usual care (UC) and mailed targeted print (TP) education, CGRA uptake would be highest among women receiving a phone-based tailored risk counseling and navigation intervention (TCN).

METHODS

In this three-arm randomized trial, women with ovarian or high-risk breast cancer were recruited from statewide cancer registries in Colorado, New Jersey, and New Mexico. Participants assigned to TP received a mailed educational brochure. Participants assigned to TCN received the mailed educational brochure, an initial phone-based psychoeducational session with a health coach, a follow-up letter, and a follow-up navigation phone call.

RESULTS

Participants' average age was 61 years, 25.4% identified as Hispanic, 5.9% identified as non-Hispanic Black, and 17.5% lived in rural areas. At 6 months, more women in TCN received CGRA (18.7%) than those in TP (3%; odds ratio, 7.4; 95% CI, 3.0 to 18.3; P < .0001) or UC (2.5%; odds ratio, 8.9; 95% CI, 3.4 to 23.5; P < .0001). There were no significant differences in CGRA uptake between TP and UC. Commonly cited barriers to genetic counseling were lack of provider referral (33.7%) and cost (26.5%), whereas anticipated difficulty coping with test results (14.0%) and cost (41.2%) were barriers for genetic testing.

CONCLUSION

TCN increased CGRA uptake in a group of geographically and ethnically diverse high-risk breast and ovarian cancer survivors. Remote personalized interventions that incorporate evidence-based health communication and behavior change strategies may increase CGRA among women recruited from statewide cancer registries.

Clinical efficacy of PARP inhibitors in breast cancer

BRCA1 and BRCA2 are key tumor suppressor genes that are essential for the homologous recombination DNA repair pathway. Loss of function mutations in these genes result in hereditary breast and ovarian cancer syndromes, which comprise approximately 5% of cases. BRCA1/2 mutations are associated with younger age of diagnosis and increased risk of recurrences. The concept of synthetic lethality led to the development of PARP inhibitors which cause cell cytotoxicity via the inhibition of PARP1, a key DNA repair protein, in cells with germline BRCA1/2 mutations. Although still poorly understood, the most well-acknowledged proposed mechanisms of action of PARP1 inhibition include the inhibition of single strand break repair, PARP trapping, and the upregulation of non-homologous end joining. Olaparib and talazoparib are PARP inhibitors that have been approved for the management of HER2-negative breast cancer in patients with germline BRCA1/2 mutations. This review article highlights the clinical efficacy of PARP inhibitors in patients with HER2-negative breast cancer in early and advanced settings.

Association Between Biomarkers and Clinical Outcomes of Pembrolizumab Monotherapy in Patients With Metastatic Triple-Negative Breast Cancer: KEYNOTE-086 Exploratory Analysis

PURPOSE

In the two-cohort phase II KEYNOTE-086 study (ClinicalTrials.gov identifier: NCT02447003), first-line and second-line or later pembrolizumab monotherapy demonstrated antitumor activity in metastatic triple-negative breast cancer (mTNBC; N = 254). This exploratory analysis evaluates the association between prespecified molecular biomarkers and clinical outcomes.

METHODS

Cohort A enrolled patients with disease progression after one or more systemic therapies for metastatic disease irrespective of PD-L1 status; Cohort B enrolled patients with previously untreated PD-L1-positive (combined positive score [CPS] ≥ 1) metastatic disease. The association between the following biomarkers as continuous variables and clinical outcomes (objective response rate [ORR], progression-free survival [PFS], and overall survival [OS]) was evaluated: PD-L1 CPS (immunohistochemistry), cluster of differentiation 8 (CD8; immunohistochemistry), stromal tumor-infiltrating lymphocyte (sTIL; hematoxylin and eosin staining), tumor mutational burden (TMB; whole-exome sequencing [WES]), homologous recombination deficiency-loss of heterozygosity, mutational signature 3 (WES), mutational signature 2 (apolipoprotein B mRNA editing catalytic polypeptide-like; WES), T-cell-inflamed gene expression profile (Tcell_infGEP; RNA sequencing), and 10 non-Tcell_infGEP signatures (RNA sequencing); Wald test P values were calculated, and significance was prespecified at α = 0.05.

RESULTS

In the combined cohorts (A and B), PD-L1 (P = .040), CD8 (P < .001), sTILs (P = .012), TMB (P = .007), and Tcell_infGEP (P = .011) were significantly associated with ORR; CD8 (P < .001), TMB (P = .034), Signature 3 (P = .009), and Tcell_infGEP (P = .002) with PFS; and CD8 (P < .001), sTILs (P = .004), TMB (P = .025), and Tcell_infGEP (P = .001) with OS. None of the non-Tcell_infGEP signatures were associated with outcomes of pembrolizumab after adjusting for the Tcell_infGEP.

CONCLUSION

In this exploratory biomarker analysis from KEYNOTE-086, baseline tumor PD-L1, CD8, sTILs, TMB, and Tcell_infGEP were associated with improved clinical outcomes of pembrolizumab and may help identify patients with mTNBC who are most likely to respond to pembrolizumab monotherapy.

Uveitis, a rare but important complication of adjuvant zoledronic acid for early-stage breast cancer

Bisphosphonates such as zoledronic acid are an important part of adjuvant therapy to reduce the risk of recurrence in early-stage breast cancer. Uveitis remains one of the lesser-known side effects of zoledronic acid; prompt recognition is essential to ensure patients receive appropriate and timely care to help prevent permanent vision loss. We report a case of anterior uveitis in a postmenopausal woman who presented with visual symptoms after receiving the first dose of zoledronic acid. This case report serves to educate and increase awareness of the risk of uveitis in patients who are given zoledronic acid. This is the first and only reported case of zoledronic acid when used in the adjuvant setting for the treatment of breast cancer.

Abstract P2-12-15: Neoadjuvant liposomal doxorubicin and carboplatin is effective and tolerable for the treatment of early stage triple negative breast cancer

Background: The addition of neoadjuvant platinums to standard chemotherapy regimens for triple negative breast cancer (TNBC) improves rates of pathologic complete response (pCR). Our prior trial combining carboplatin (CAR) with liposomal doxorubicin (DOX) for metastatic TNBC showed good response rates with minimal side effects and allows for higher platinum dosing. We hypothesized that the doublet of DOX+CAR is effective and tolerable in the neoadjuvant setting for TNBC and tumor genomics may identify biomarkers of complete response and actionable targets. Methods: A phase II single arm trial was conducted for patients (pts) diagnosed with stage II-III TNBC. Patients received 4 cycles of neoadjuvant carboplatin (AUC 5) and liposomal doxorubicin (30mg/m2) administered every 28 days, then underwent definitive breast surgery followed by 12 weeks of adjuvant paclitaxel 80 mg/m2 administered weekly. Primary and secondary clinical endpoints were rate of pCR and two year recurrence free survival (RFS) and overall survival (OS), respectively. Cardiac safety of the combination was assessed. Fresh residual tumor samples were obtained at time of surgery for generation of patient derived xenografts (PDX). Whole genome sequencing (WGS) and RNA sequencing will be performed to evaluate specific patterns of small-variant mutations and patterns of structural variants to identify which patients are likely to have pCR. Results: From 2/2015 to 6/2021, 62 pts were enrolled, 8 pts withdrew consent either prior to treatment or completion of neoadjuvant therapy and/or surgery. Median age of the cohort was 55.4 years. There was high participation by under-represented groups: 17.0% African American, 20.8% Asian, 13.2% Hispanic. Most histologies were invasive ductal carcinoma, but included apocrine, pleomorphic lobular, and metaplastic subtypes. 53 pts completed all 4 cycles of neoadjuvant DOX+CAR, followed by definitive surgery; 1 pt progressed after 1 cycle and proceeded to surgery thereafter. 30.2% (16) pts achieved pCR, and residual cancer burden (RCB) will be reported in patients with residual disease. Of the 53 pts who completed 4 cycles of treatment, 5 pts progressed (recurrence or death) within two years from time of surgery (4 distant and 1 local recurrence), yielding the 2-year recurrence-free-survival rate of 90.3% (95%CI 81.0%, 99.6%). The most common toxicities during DOX+CAR were grade 1 fatigue in 50 pts (92.6%), grade 1 anemia in 44 pts (81.5%), and grade 3/4 neutropenia in 16 pts (29.6%); these pts received GCSF support with subsequent cycles; febrile neutropenia occurred in 1 pt (1.9%) in this group. Only 10 pts (18.5%) had grade 1 alopecia, 5 pts (9.3%) had grade 2 alopecia, 2 pts (3.7%) had grade 3 thrombocytopenia. There were no delays in treatment due to cardiotoxicity or complications from surgical healing. Of the 37 pts who had residual disease, PDX was attempted in 21 pts, and 16 (76%) PDX were established, including those for 4 patients experiencing recurrence. WGS and RNA sequencing data from pre-treatment and residual disease samples will be analyzed and reported.Conclusion: 4 cycles of neoadjuvant DOX+CAR achieved rate of pCR similar to standard regimens and has good tolerability. Post chemotherapy PDX is feasible and may help identify targeted approaches for patients with resistant disease. These results warrant further evaluation of this combination for early stage TNBC.

Citation Format: Nancy Chan, Shou-en Lu, Yue Wang, Gregory M Riedlinger, Coral Omene, Mridula George, Jyoti Malhotra, Maria Kowzun, Firas G Eladoumikdachi, Lindsay B Potdevin, Shicha Kumar, Kant Matsuda, Shruti Desai, Nayana Patel, Deborah L Toppmeyer, Shridar Ganesan, Kim Hirshfield. Neoadjuvant liposomal doxorubicin and carboplatin is effective and tolerable for the treatment of early stage triple negative breast cancer [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P2-12-15.

Clinical and Pharmacologic Differences of CDK4/6 Inhibitors in Breast Cancer

Targeted therapies such as Cyclin Dependent Kinase 4 and 6 (CDK 4/6) inhibitors have improved the prognosis of metastatic hormone receptor (HR) positive breast cancer by combating the resistance seen with traditional endocrine therapy. The three approved agents currently in the market are palbociclib, ribociclib and abemaciclib. Besides the overall similarities associated with CDK4/6 inhibition, there are differences between the three approved agents that may explain the differences noted in unique clinical scenarios- monotherapy, patients with brain metastases or use in the adjuvant setting. This review article will explore the preclinical and pharmacological differences between the three agents and help understand the benefits seen with these agents in certain subgroups of patients with metastatic HR positive breast cancer.

Durable Response to PD1 Inhibitor Pembrolizumab in a Metastatic, Metaplastic Breast Cancer

Metaplastic breast cancer (MBC) is a rare and aggressive subtype of breast cancer. Tumor characteristics typically feature estrogen receptor, progesterone receptor, and HER2-negative, triple-negative breast cancer (TNBC), with a poorer prognosis relative to pure invasive ductal or lobular disease. Resistance to chemotherapy often leads to local recurrence and distant metastasis. Genomic profiling has identified multiple molecular abnormalities that may translate to targetable therapies in MBC. These tumors are known to display higher PD-L1 expressivity than other subtypes of breast cancer, and disease control with pembrolizumab and chemotherapy has been documented. We identify a patient with metastatic, metaplastic TNBC, with mesenchymal components and osseous differentiation, who completed 2 years of pembrolizumab treatment and has remained without evidence of disease after 32 months of observation, while maintaining good quality of life. Future efforts should focus on immunotherapy response with respect to the various subtypes of MBC, and treatment should continue to be incorporated in clinical trials to maximize disease response.

SARS-CoV-2 nosocomial infection: Real-world results of environmental surface testing from a large tertiary cancer center

BACKGROUND

Despite consensus guidelines, concern about severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission has dissuaded patients with cancer from seeking medical care. Studies have shown that contaminated surfaces may contain viable virus for up to 72 hours in laboratory settings. The purpose of this study was to investigate contamination of SARS-CoV-2 on commonly used environmental surfaces in a tertiary cancer care center.

METHODS

This study evaluated the incidence of SARS-CoV-2 viral RNA in high-touch outpatient and inpatient cancer center spaces. Surfaces were tested over a 2-week period after patient or staff exposure but before scheduled disinfection services according to the World Health Organization protocols for coronavirus disease 2019 (COVID-19) surface sampling. Samples were analyzed via reverse transcriptase-polymerase chain reaction for the presence of SARS-CoV-2 RNA.

RESULTS

Two hundred four environmental samples were obtained from inpatient and outpatient oncology clinics and infusion suites, and they were categorized as 1) public areas, 2) staff areas, or 3) medical equipment. One hundred thirty surfaces from 2 outpatient hematology and oncology clinics and 36 surfaces from an inpatient leukemia/lymphoma/chimeric antigen receptor T-cell unit were examined, and all 166 samples were negative for SARS-CoV-2. One of 38 samples (2.6%) from COVID-19+ inpatient units was positive. Altogether, the positive test rate for SARS-CoV-2 RNA across all surfaces was 0.5% (1 of 204).

CONCLUSIONS

This prospective, systematic quality assurance investigation of real-world environmental surfaces, performed in inpatient and outpatient hematology/oncology units, revealed overall negligible detection of SARS-CoV-2 RNA when strict mitigation strategies against COVID-19 transmission were instituted.

LAY SUMMARY

The potential risks of nosocomial infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have deterred patients with cancer from seeking timely care despite consensus guidelines. This study has found negligible rates of environmental contamination with SARS-CoV-2 across a multitude of commonly used surfaces in outpatient and inpatient hematology/oncology settings with adherence to strict infection control protocols.

Race, Ethnicity, and Clinical Outcomes in Hormone Receptor-Positive, HER2-Negative, Node-Negative Breast Cancer in the Randomized TAILORx Trial

BACKGROUND

Black race is associated with worse outcomes in early breast cancer. We evaluated clinicopathologic characteristics, the 21-gene recurrence score (RS), treatment delivered, and clinical outcomes by race and ethnicity among women who participated in the Trial Assigning Individualized Options for Treatment.

METHODS

The association between clinical outcomes and race (White, Black, Asian, other or unknown) and ethnicity (Hispanic vs non-Hispanic) was examined using proportional hazards models. All P values are 2-sided.

RESULTS

Of 9719 eligible women with hormone receptor-positive, HER2-negative, node-negative breast cancer, there were 8189 (84.3%) Whites, 693 (7.1%) Blacks, 405 (4.2%) Asians, and 432 (4.4%) with other or unknown race. Regarding ethnicity, 889 (9.1%) were Hispanic. There were no substantial differences in RS or ESR1, PGR, or HER2 RNA expression by race or ethnicity. After adjustment for other covariates, compared with White race, Black race was associated with higher distant recurrence rates (hazard ratio [HR] = 1.60, 95% confidence intervals [CI] = 1.07 to 2.41) and worse overall survival in the RS 11-25 cohort (HR = 1.51, 95% CI = 1.06 to 2.15) and entire population (HR = 1.41, 95% CI = 1.05 to 1.90). Hispanic ethnicity and Asian race were associated with better outcomes. There was no evidence of chemotherapy benefit for any racial or ethnic group in those with a RS of 11-25.

CONCLUSIONS

Black women had worse clinical outcomes despite similar 21-gene assay RS results and comparable systemic therapy in the Trial Assigning Individualized Options for Treatment. Similar to Whites, Black women did not benefit from adjuvant chemotherapy if the 21-gene RS was 11-25. Further research is required to elucidate the basis for this racial disparity in prognosis.

Abstract PD14-07: Association between biomarkers and response to pembrolizumab in patients with metastatic triple-negative breast cancer (mTNBC): Exploratory analysis from KEYNOTE-086

Background: In the phase 2 KEYNOTE-086 study (NCT02447003), pembrolizumab monotherapy had durable antitumor activity in a subset of patients with previously treated mTNBC (cohort A; n = 170) and in patients with previously untreated PD-L1-positive mTNBC (cohort B; n = 84). In this exploratory analysis of KEYNOTE-086, we evaluated the association between several biomarkers and response to pembrolizumab. Methods: Cohort A enrolled patients regardless of PD-L1 expression who had documented disease progression following ≥1 systemic therapy for metastatic disease. Cohort B enrolled patients with PD-L1-positive (combined positive score [CPS] ≥1) tumors who had not received prior systemic therapy for metastatic disease. Immunohistochemistry was used to measure PD-L1 CPS and CD8 density; H&E staining for percentage of stromal tumor infiltrating lymphocytes (sTILs); RNA-sequencing for 18-gene T-cell-inflamed gene expression profile (GEP), angiogenesis, and glycolysis signatures; and whole exome sequencing (paired tumor and germline) for TMB (TMB-H defined as ≥175 mut/exome), HRD-LOH (DNA damage), Signature 3, and APOBEC. Biomarkers were analyzed as continuous variables in cohorts A and B combined and individually. Area under the receiver operating characteristic curve was estimated between each biomarker and overall response rate (ORR). Wald test P-values were calculated using logistic regression adjusted for cohort and Eastern Cooperative Oncology Group performance status. Germline and somatic BRCA1/2 mutations were pooled; one-sided P-value was calculated using Fisher’s exact test. Spearman’s correlation was used for correlations. Results: Biomarker data were available in the following number of patients: 253 (99.6%; PD-L1), 204 (80.3%; CD8), 187 (73.6%; GEP), 171 (67.3%; TMB/HRD), 228 (89.8%; sTILs), 163 (64.2%; Signature 3/APOBEC), and 132 (52.0%; angiogenesis/glycolysis). When data from cohorts A and B were combined, PD-L1 CPS (median 2; IQR 0-10), CD8 (median 159; IQR 62-319), GEP (median -0.34; IQR -0.57 to -0.11), TMB (median 82 mut/exome; IQR 50-139), and sTILs (median 5; IQR 2-20) were significantly associated with ORR (Table). There were moderate correlations between PD-L1 and GEP (r = 0.532), PD-L1 and sTILs (r = 0.451), and GEP and sTILs (r = 0.490). No correlation was observed between TMB and PD-L1 (r = 0.038), GEP (r = -0.035), and sTILs (r = -0.031). When cohorts were combined, TMB was significantly associated with ORR, PFS, and OS after adjustment for PD-L1, GEP, CD8, or sTILs. HRD-LOH score, Signature 3, and APOBEC were not significantly associated with ORR (Table); P for BRCA1/2 was 0.2385. The angiogenesis signature was associated with lack of response while the glycolysis signature was associated with response to pembrolizumab (Table). Conclusions: In this exploratory biomarker analysis from KEYNOTE-086, higher levels of PD-L1, GEP, TMB, CD8 IHC, sTILs, and the glycolysis signature were associated with increased response to pembrolizumab monotherapy. These findings may help identify patients with mTNBC who are most likely to respond to pembrolizumab.

Table. Association of Biomarkers as Continuous Variables With Pembrolizumab Objective ResponseBiomarkerCombined Cohorts AUCCombined Cohorts P*Combined Cohorts Multitest corrected PCohort A AUCCohort B AUCPD-L10.6740.040-0.5440.654GEP0.7480.003-0.8370.561TMB0.6270.007-0.5480.710CD8 IHC0.760.000020.000120.850.68sTILs0.6710.012-0.6320.641HRD0.3940.874-0.5220.316Signature 30.6830.072-0.6970.736APOBEC0.5280.537-0.6740.623Angiogenesis0.6770.0090.0450.6610.731Glycolysis0.6120.0090.0360.8590.459AUC, area under the curve.*One-sided P-values are shown for all biomarkers except for Signature 3 and APOBEC, for which 2-sided P-values are shown.

Citation Format: Sherene Loi, Peter Schmid, Javier Cortes, David W. Cescon, Eric P. Winer, Deborah L. Toppmeyer, Hope S. Rugo, Michelino De Laurentiis, Rita Nanda, Hiroji Iwata, Ahmad Awada, Antoinette R. Tan, Roberto Salgado, Vassiliki Karantza, Petar Jelinic, Anran Wang, Lingkang Huang, Razvan Cristescu, Lakshman Annamalai, Jennifer Yearley, Jennifer Yearley, Sylvia Adams. Association between biomarkers and response to pembrolizumab in patients with metastatic triple-negative breast cancer (mTNBC): Exploratory analysis from KEYNOTE-086 [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PD14-07.

Testing considerations for phosphatidylinositol-3-kinase catalytic subunit alpha as an emerging biomarker in advanced breast cancer

Breast cancer is the most common cancer in women, and approximately 71% of carcinomas are hormone receptor‐positive (HR+) and human epidermal growth factor receptor 2‐not‐amplified (HER2‐negative). Pathogenesis of breast cancer is associated with dysregulation of several signaling pathways, including the phosphatidylinositol‐3‐kinase (PI3K) pathway. PIK3CA, the gene encoding PI3K catalytic subunit p110α, is mutated in 20%‐40% of breast cancer patients. Several PI3K inhibitors have been developed and one, alpelisib, was recently approved for use in PIK3CA‐mutated, HR+, HER2‐negative advanced breast cancer. There are numerous types of assays and methods used in clinical studies to determine PIK3CA status in cancers. Additionally, there are several factors to consider for PIK3CA testing in clinical practice, including choice of assay, source of sample, and test timing. In this review, we discuss the use of PIK3CA as a biomarker to guide treatment decisions in patients with HR+, HER2‐negative advanced breast cancer, as well as practical considerations and recommendations for testing.

TBCRC 031: Randomized Phase II Study of Neoadjuvant Cisplatin Versus Doxorubicin-Cyclophosphamide in Germline BRCA Carriers With HER2-Negative Breast Cancer (the INFORM trial)

PURPOSE

Platinum compounds have activity in triple-negative breast cancer (TNBC) in germline BRCA mutation carriers (BRCA carriers). Limited data exist for estrogen receptor (ER)-positive (+) breast cancer among BRCA carriers. INFORM is a randomized, multicenter, phase II trial comparing pathologic complete response (pCR) rates (ypT0/is, N0) after neoadjuvant single-agent cisplatin (CDDP) versus doxorubicin-cyclophosphamide (AC) in BRCA carriers with stage I-III human epidermal growth factor receptor 2 (HER2)-negative breast cancer. Secondary objectives included residual cancer burden scores (RCB) of 0 or 1 (combined) and toxicity. The goal was to determine whether pCR was ≥ 20% higher with CDDP than AC.

PATIENTS AND METHODS

BRCA carriers with cT1-3 (≥ 1.5 cm), cN0-3 HER2-negative breast cancer were randomly assigned to preoperative CDDP (75 mg/m² every 3 weeks × 4 doses) or AC (doxorubicin 60 mg/m²; cyclophosphamide 600 mg/m² every 2-3 weeks × 4 doses) followed by surgery. Pathologic responses were confirmed by central review.

RESULTS

A total of 118 patients were randomly assigned; 117 were included in outcome analyses. Mean age was 42 years (range, 24-73 years); 69% were BRCA1+, 30% were BRCA2+, and 2% had both mutations. Clinical stage was I for 19%, II for 63%, and III for 18%; 45% had nodal involvement at baseline. Seventy percent had TNBC. Clinical and tumor characteristics were well matched between treatment arms. The pCR rate was 18% with CDDP and 26% with AC, yielding a risk ratio (RR) of 0.70 (90% CI, 0.39 to 1.2). The risk of RCB 0 or 1 (RCB 0/1) was 33% with CDDP and 46% with AC (RR, 0.73; 90% CI, 0.50 to 1.1). Both regimens were generally well tolerated without unexpected toxicities.

CONCLUSION

pCR or RCB 0/1 is not significantly higher with CDDP than with AC in BRCA carriers with stage I-III HER2-negative breast cancer for both TNBC and ER+/HER2-negative disease.

Clinical Outcomes in Early Breast Cancer With a High 21-Gene Recurrence Score of 26 to 100 Assigned to Adjuvant Chemotherapy Plus Endocrine Therapy: A Secondary Analysis of the TAILORx Randomized Clinical Trial

Importance

A high 21-gene recurrence score (RS) by breast cancer assay is prognostic for distant recurrence of early breast cancer after local therapy and endocrine therapy alone, and for chemotherapy benefit.

Objective

To describe clinical outcomes for women with a high RS who received adjuvant chemotherapy plus endocrine therapy in the TAILORx trial, a population expected to have a high distant recurrence rate with endocrine therapy alone.

Design, Setting, and Participants

In this secondary analysis of data from a multicenter randomized clinical trial, 1389 women with hormone receptor-positive, ERBB2-negative, axillary node-negative breast cancer, and a high RS of 26 to 100 were prospectively assigned to receive adjuvant chemotherapy in addition to endocrine therapy. The analysis was conducted on May 12, 2019.

Interventions

The adjuvant chemotherapy regimen was selected by the treating physician.

Main Outcomes and Measures

Freedom from recurrence of breast cancer at a distant site, and freedom from recurrence, second primary cancer, and death (also known as invasive disease-free survival [IDFS]).

Results

Among the 9719 eligible women, with a mean age of 56 years (range 23-75 years), 1389 (14%) had a recurrence score of 26 to 100, of whom 598 (42%) had an RS of 26 to 30 and 791 (58%) had an RS of 31 to 100. The most common chemotherapy regimens included docetaxel/cyclophosphamide in 589 (42%), an anthracycline without a taxane in 334 (24%), an anthracycline and taxane in 244 (18%), cyclophosphamide/methotrexate/5-fluorouracil in 52 (4%), other regimens in 81 (6%), and no chemotherapy in 89 (6%). At 5 years, the estimated rate of freedom from recurrence of breast cancer at a distant site was 93.0% (standard error [SE], 0.8%), freedom of recurrence of breast cancer at a distant and/or local regional site 91.0% (SE, 0.8%), IDFS 87.6% (SE, 1.0%), and overall survival 95.9% (SE, 0.6%).

Conclusions and Relevance

The estimated rate of freedom from recurrence of breast cancer at a distant site in women with an RS of 26 to 100 treated largely with taxane and/or anthracycline-containing adjuvant chemotherapy regimens plus endocrine therapy in the prospective TAILORx trial was 93% at 5 years, an outcome better than expected with endocrine therapy alone in this population.

Trial Registration

ClinicalTrials.gov identifier: NCT00310180.

Abstract GS6-03: Cisplatin versus doxorubicin/cyclophosphamide as neoadjuvant treatment in germline BRCA mutation carriers (BRCA carriers) with HER2-negative breast cancer: Results from the INFORM trial (TBCRC 031)

Background: Single-agent platinum compounds have significant clinical activity in the neoadjuvant and metastatic settings for triple-negative breast cancer (TNBC) in BRCA mutation carriers. Limited data exist regarding activity in estrogen receptor (ER)-positive breast cancer among BRCA carriers. The INFORM trial is an investigator-initiated, randomized, multicenter, phase II study comparing pathologic complete response (pCR) rates with neoadjuvant single-agent cisplatin (CDDP) versus doxorubicin/cyclophosphamide (AC) in BRCA carriers with newly-diagnosed Stage I-III HER2-negative breast cancer.

Methods: BRCA carriers with cT1-3 (≥1.5 cm), cN0-3 HER2-negative breast cancer were randomized (stratified by site and ER status) 1:1 to preoperative CDDP (75mg/m2 every 3 wks x 4) or AC (doxorubicin 60 mg/m2; cyclophosphamide 600 mg/m2 every 2-3 wks x 4) followed by surgery. Prior chemotherapy was not allowed; subsequent adjuvant therapy was selected by treating clinicians. Baseline tumor features and pathologic responses were centrally determined. The primary endpoint was pCR (ypT0/is, N0). Based on a 2-sided α=0.1, a sample size of 170 provided 80% power to detect an improvement in pCR from 30% with AC to 50% with CDDP. Slow accrual led to early trial closure. We used an intent-to-treat approach and log-binomial regression to calculate risk ratios (95% confidence intervals (CI)), adjusting for ER status.

Results: We randomized 118 patients; 117 were included in outcome analyses. The mean age was 42 years (range: 24-73); 69% were BRCA1+, 30% BRCA2+, and 2% had both mutations. Clinical stage was I for 19%, II for 63%, and III for 18%; 45% of patients had nodal involvement at baseline. Most patients (70%) had TNBC (ER/PR &lt;10%). Histologic type and grade, clinical stage, lymphovascular invasion and tumor infiltrating lymphocytes were similar between treatment arms. Four patients did not complete protocol-assigned therapy and 7 received additional chemotherapy before surgery; all were assessed as not attaining pCR. The pCR rate was 18% in the CDDP arm and 26% in the AC arm, yielding a crude risk ratio of 0.70 (95% CI: 0.35-1.4); results were similar when adjusting for ER status. Table 1 shows pathologic responses.

Table 1: Intention-to-treat analysis comparing CDDP to ACCDDP n=60 n (%)AC* n=57 n (%)Crude Risk Ratio (95% CI)Adjusted Risk Ratio§ (95% CI)Pathologic complete responseResidual cancer burden score: 0All participants11 (18)15 (26)0.70 (0.35-1.4)0.67 (0.35-1.3)Triple negative (ER and PR &lt;10%)10 (23)11 (29)0.79 (0.37-1.6)–Hormone receptor positive (ER or PR ≥10%)1 (6)4 (21)0.30 (0.04-2.4)–Residual cancer burden¥Residual cancer burden score: 0 or 120 (33)26 (46)0.73 (0.46-1.2)0.72 (0.46-1.1)*One patient never received treatment, and is not included in the intent-to-treat analysis.§Adjusted for estrogen receptor status using 10% cutoff¥Residual cancer burden score of 0 or 1 could not be determined for 10 participants; they were assumed to have a residual cancer burden score greater than 1

Conclusion: While CDDP has single-agent activity in BRCA carriers with HER2-negative breast cancer, the pCR rate with CDDP is not higher than with standard AC chemotherapy. CDDP activity was notably lower in BRCA carriers with hormone-receptor positive breast cancer, though the sample size was small. Study-collected tumor and blood samples are being analyzed for biomarkers of response. Clinical information: NCT01670500.

Funding: Breast Cancer Research Foundation; Susan G. Komen for the Cure; Myriad Genetics, Inc.

Citation Format: Nadine Tung, Banu Arun, Erin Hofstatter, Michele R. Hacker, Deborah L. Toppmeyer, Steven J. Isakoff, Virginia Borges, Robert D. Legare, Claudine Isaacs, Antonio C. Wolff, Paul K. Marcom, Erica L. Mayer, Paulina B. Lange, Andrew J. Goss, Ian E. Krop, Eric P. Winer, Stuart J. Schnitt, Judy E. Garber. Cisplatin versus doxorubicin/cyclophosphamide as neoadjuvant treatment in germline BRCA mutation carriers (BRCA carriers) with HER2-negative breast cancer: Results from the INFORM trial (TBCRC 031) [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr GS6-03.

Personalized Management of Chemotherapy-Induced Peripheral Neuropathy Based on a Patient Reported Outcome: CALGB 40502 (Alliance)

Chemotherapy-induced peripheral neuropathy (henceforth, neuropathy) is often dose limiting and is generally managed by empirical dose modifications. We aimed to (1) identify an early time point that is predictive of future neuropathy using a patient-reported outcome and (2) propose a dose-adjustment algorithm based on simulated data to manage neuropathy. In previous work, a dose-neuropathy model was developed using dosing and patient-reported outcome data from Cancer and Leukemia Group B 40502 (Alliance), a randomized phase III trial of paclitaxel, nanoparticle albumin-bound paclitaxel or ixabepilone as first-line chemotherapy for locally recurrent or metastatic breast cancer. In the current work, an early time point that is predictive of the future severity of neuropathy was identified based on predictive accuracy of the model. Using the early data and model parameters, simulations were conducted to propose a dose-adjustment algorithm for the prospective management of neuropathy in individual patients. The end of the first 3 cycles (12 weeks) was identified as the early time point based on a predictive accuracy of 75% for the neuropathy score after 6 cycles. For paclitaxel, nanoparticle albumin-bound paclitaxel, and ixabepilone, simulations with the proposed dose-adjustment algorithm resulted in 61%, 48%, and 35% fewer patients, respectively, with neuropathy score ≥8 after 6 cycles compared to no dose adjustment. We conclude that early patient-reported outcome data on neuropathy can be used to guide dose adjustments in individual patients that reduce the severity of future neuropathy. Prospective validation of this approach should be undertaken in future studies.

Clinical and Genomic Risk to Guide the Use of Adjuvant Therapy for Breast Cancer

BACKGROUND

The use of adjuvant chemotherapy in patients with breast cancer may be guided by clinicopathological factors and a score based on a 21-gene assay to determine the risk of recurrence. Whether the level of clinical risk of breast cancer recurrence adds prognostic information to the recurrence score is not known.

METHODS

We performed a prospective trial involving 9427 women with hormone-receptor-positive, human epidermal growth factor receptor 2-negative, axillary node-negative breast cancer, in whom an assay of 21 genes had been performed, and we classified the clinical risk of recurrence of breast cancer as low or high on the basis of the tumor size and histologic grade. The effect of clinical risk was evaluated by calculating hazard ratios for distant recurrence with the use of Cox proportional-hazards models. The initial endocrine therapy was tamoxifen alone in the majority of the premenopausal women who were 50 years of age or younger.

RESULTS

The level of clinical risk was prognostic of distant recurrence in women with an intermediate 21-gene recurrence score of 11 to 25 (on a scale of 0 to 100, with higher scores indicating a worse prognosis or a greater potential benefit from chemotherapy) who were randomly assigned to endocrine therapy (hazard ratio for the comparison of high vs. low clinical risk, 2.73; 95% confidence interval [CI], 1.93 to 3.87) or to chemotherapy plus endocrine (chemoendocrine) therapy (hazard ratio, 2.41; 95% CI, 1.66 to 3.48) and in women with a high recurrence score (a score of 26 to 100), all of whom were assigned to chemoendocrine therapy (hazard ratio, 3.17; 95% CI, 1.94 to 5.19). Among women who were 50 years of age or younger who had received endocrine therapy alone, the estimated (±SE) rate of distant recurrence at 9 years was less than 5% (≤1.8±0.9%) with a low recurrence score (a score of 0 to 10), irrespective of clinical risk, and 4.7±1.0% with an intermediate recurrence score and low clinical risk. In this age group, the estimated distant recurrence at 9 years exceeded 10% among women with a high clinical risk and an intermediate recurrence score who received endocrine therapy alone (12.3±2.4%) and among those with a high recurrence score who received chemoendocrine therapy (15.2±3.3%).

CONCLUSIONS

Clinical-risk stratification provided prognostic information that, when added to the 21-gene recurrence score, could be used to identify premenopausal women who could benefit from more effective therapy. (Funded by the National Cancer Institute and others; ClinicalTrials.gov number, NCT00310180.).

Abstract P1-15-14: Neoadjuvant liposomal doxorubicin and carboplatin is effective and tolerable for the treatment of triple negative breast cancer

Background: The use of neoadjuvant platinum with taxane for triple negative breast cancer (TNBC) has gained increased attention for improving rates of pathologic complete response (pCR). Our prior trial combining carboplatin (CAR) with liposomal doxorubicin (DOX) for metastatic TNBC showed good response rates with minimal side effects while allowing for greater platinum dosing compared to a taxane combination. We hypothesized that the doublet of DOX+CAR is effective and tolerable in the neoadjuvant setting for TNBC and that tumor genomics may aid in determining those patients most likely to benefit.

Methods: A phase II single arm trial was conducted for patients (pts) diagnosed with stage II-III TNBC. Patients received 4 cycles of neoadjuvant carboplatin (AUC 5) and liposomal doxorubicin (30mg/m2) administered every 28 days, then underwent definitive breast surgery followed by 12 weeks of adjuvant paclitaxel 80 mg/m2 administered weekly. Primary and secondary clinical endpoints were rate of pCR and two year recurrence free survival (RFS) and overall survival (OS), respectively. Cardiac safety of the combination was assessed. Fresh residual tumor samples were obtained at time of surgery for generation of patient derived xenografts (PDX). Tumor genomic profiling was done to determine the mutational spectrum, association of this spectrum in primary tumors with achieving pCR, and identifying alternative treatment strategies for PDX evaluation for patients with resistant disease.

Results: From 2/2015 to 5/2018, 36 pts were enrolled and 32 completed treatment; 4 pts await definitive surgery; 12 (33%) are two years from diagnosis. Median age of the cohort was 53 years. There was high participation by under-represented groups: 23% African American, 20% Asian, 14% Hispanic. Most histologies were invasive ductal but included apocrine, pleomorphic lobular, and metaplastic subtypes. Of the 32 pts who completed surgery, 34% (11) achieved pCR and 64% (23) had clinical response on serial physical exam. At 2 years, there were 2 distant and 1 local recurrence. The most common toxicities during DOX+CAR were grade 1 nausea in 19 pts (53%), grade 3/4 neutropenia occurred in 10 pts (28%); these pts received GCSF support with subsequent cycles; febrile neutropenia occurred in 1 pt (3%) in this group. Grade 3 thrombocytopenia (2 pts), pruritis (1 pt), and mucositis (1 pt) were observed. Only 6 pts (17%) had grade 1 alopecia. There were no delays in treatment due to cardiotoxicity or complications from surgical healing. TP53 (93%), PI3K/PTEN (26.6%), and NOTCH (20%) were the most commonly altered pathways. Structural variants, such as amplifications, rearrangements, and frameshifts were the most frequent alterations detected. Of the 25 pts who had residual disease, PDX was attempted from 14 pts, and 10 (71%) PDX were established, including those for all 3 patients experiencing recurrence.

Conclusion: Neoadjuvant DOX+CAR demonstrated good efficacy and tolerability. Post-chemotherapy PDX is feasible and may help identify targeted approaches for patients with resistant disease. These results warrant further evaluation of this combination for early stage TNBC.

Citation Format: Chan N, Riedlinger GM, Lu S-e, Pham KT, Kirstein LJ, Eladoumikdachi FG, George MA, Potdevin LB, Kowzun MJ, Desai SA, Tang DM, Omene CO, Wong ST, Rodriguez-Rust L, Kumar S, Kearney TJ, Liu C, Ganesan S, Toppmeyer DL, Hirshfield KM. Neoadjuvant liposomal doxorubicin and carboplatin is effective and tolerable for the treatment of triple negative breast cancer [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 P1-15-14.

Abstract GS4-07: Race, ethnicity and clinical outcomes in hormone receptor-positive, HER2-negative, node-negative breast cancer: results from the TAILORx trial

Background: Black race is associated with worse outcomes in localized hormone receptor (HR)-positive breast cancer in population-based and in clinical trial cohorts, whether using self-identified race (Albain et al. JNCI 2009 [PMID: 19584328; Sparano et al. JNCI 2012 [PMID: 22250182) or genetically-identified race (Schneider et al. J Precision Oncol 2017 [PMID: 29333527]). This disparity persists after adjustment for treatment delivery parameters (Hershman et al. JCO 2009 [PMID:19307504]). We evaluated clinicopathologic characteristics, treatment delivered and clinical outcomes in the Trial Assigning Individualized Options for Treatment (TAILORx) by race and ethnicity (Sparano et al. NEJM 2018 [PMID: 29860917]).

Methods: The analysis included 9719 evaluable TAILORx participants. The association between clinical outcomes and race (white, black, Asian, other/unknown) and ethnicity (Hispanic vs. non-Hispanic) was examined, including invasive disease-free survival (iDFS), distant relapse-free interval (DRFI), relapse-free interval (RFI), and overall survival (OS). Proportional hazards models were fit including age (5 categories), tumor size (&gt;2 cm vs. &lt;=2 cm), histologic grade (high vs. medium vs. low vs. unknown), continuous recurrence score (RS), race, and ethnicity in the overall population and randomized treatment arms in the RS 11-25 cohort.

Results: The study population included 8189 (84%) whites, 693 (7%) blacks, 405 (4%) Asians, and 432 (4%) with other/unknown race. Regarding ethnicity, 7635 (79%) were non-Hispanic, 889 (9%) Hispanic, and 1195 (12%) unknown. There was no significant difference in RS distribution (p=0.22) in blacks compared with whites, or in median (17 vs. 17) or mean RS (19.1 vs. 18.2). There was likewise no difference in Hispanic vs. non-Hispanic ethnicity for RS distribution (p=0.72) or median (17 vs. 17) or mean RS (18.5 vs. 18.0). Black race (39% vs. 30%) and Hispanic ethnicity (39% vs. 30%) were both associated with younger age (&lt;/=50 years) at diagnosis. The use and type of adjuvant chemotherapy and endocrine therapy, and duration of endocrine therapy, were similar in black (vs. white) and Hispanic (vs. non-Hispanic) populations. In proportional hazards models, black race (compared with white race) was associated with worse clinical outcomes in the entire population and in those with a RS 11-25 (see table). Hispanic ethnicity was generally associated with better outcomes (compared with non-Hispanic ethnicity). For the cohort with a RS of 11-25, there was no evidence for chemotherapy benefit for any racial or ethnic group.

Race (black vs.white) and clinical outcomes in proportional hazards modelsClinical endpointEntire Population (N=693 black) Hazard ratio for eventRS 11-25 (N=471 black) Hazard ratio for eveniDFS1.33 (p=0.005)1.49 (p=0.001)DRFI1.21 (p=0.28)1.60 (p=0.02)RFI1.39 (p=0.02)1.80 (p&lt;0.001)OS1.52 (p=0.005)1.67 (p=0.003

Conclusions: In patients eligible and selected for participation in TAILORx, black women had worse clinical outcomes despite similar 21-gene assay RS results and comparable systemic therapy. This adds to an emerging body of evidence suggesting a biologic basis or other factors contributing to racial disparities in HR-positive breast cancer that requires further evaluation.

Citation Format: Albain K, Gray RJ, Sparano JA, Makower DF, Pritchard KI, Hayes DF, Geyer, Jr. CE, Dees EC, Goetz MP, Olson, Jr. JA, Lively T, Badve SS, Saphner TJ, Wagner LI, Whelan TJ, Ellis MJ, Paik S, Wood WC, Ravdin PM, Keane MM, Gomez HL, Reddy PS, Goggins TF, Mayer IA, Brufsky AM, Toppmeyer DL, Kaklamani VG, Berenberg JL, Abrams J, Sledge, Jr. GW. Race, ethnicity and clinical outcomes in hormone receptor-positive, HER2-negative, node-negative breast cancer: results from the TAILORx trial [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 GS4-07.

Adjuvant Chemotherapy Guided by a 21-Gene Expression Assay in Breast Cancer

BACKGROUND

The recurrence score based on the 21-gene breast cancer assay predicts chemotherapy benefit if it is high and a low risk of recurrence in the absence of chemotherapy if it is low; however, there is uncertainty about the benefit of chemotherapy for most patients, who have a midrange score.

METHODS

We performed a prospective trial involving 10,273 women with hormone-receptor-positive, human epidermal growth factor receptor 2 (HER2)-negative, axillary node-negative breast cancer. Of the 9719 eligible patients with follow-up information, 6711 (69%) had a midrange recurrence score of 11 to 25 and were randomly assigned to receive either chemoendocrine therapy or endocrine therapy alone. The trial was designed to show noninferiority of endocrine therapy alone for invasive disease-free survival (defined as freedom from invasive disease recurrence, second primary cancer, or death).

RESULTS

Endocrine therapy was noninferior to chemoendocrine therapy in the analysis of invasive disease-free survival (hazard ratio for invasive disease recurrence, second primary cancer, or death [endocrine vs. chemoendocrine therapy], 1.08; 95% confidence interval, 0.94 to 1.24; P=0.26). At 9 years, the two treatment groups had similar rates of invasive disease-free survival (83.3% in the endocrine-therapy group and 84.3% in the chemoendocrine-therapy group), freedom from disease recurrence at a distant site (94.5% and 95.0%) or at a distant or local-regional site (92.2% and 92.9%), and overall survival (93.9% and 93.8%). The chemotherapy benefit for invasive disease-free survival varied with the combination of recurrence score and age (P=0.004), with some benefit of chemotherapy found in women 50 years of age or younger with a recurrence score of 16 to 25.

CONCLUSIONS

Adjuvant endocrine therapy and chemoendocrine therapy had similar efficacy in women with hormone-receptor-positive, HER2-negative, axillary node-negative breast cancer who had a midrange 21-gene recurrence score, although some benefit of chemotherapy was found in some women 50 years of age or younger. (Funded by the National Cancer Institute and others; TAILORx ClinicalTrials.gov number, NCT00310180 .).

Abstract P1-07-04: Physical activity, weight and outcomes in patients receiving first-line chemotherapy for metastatic breast cancer: Results from CALGB 40502 (Alliance)

Background: Obesity and inactivity are associated with an increased risk of cancer-related and overall mortality in women with early-stage breast cancer, but there are few data in advanced breast cancer.

Methods: C40502 was a Phase III trial of first-line chemotherapy for patients with metastatic breast cancer (MBC). Participants were randomized to weekly paclitaxel, nab-paclitaxel or ixabepilone. Height and weight at the time of study enrollment were abstracted from medical records. After study activation, the protocol was amended to collect physical activity (PA) data. Participants completed the Nurses' Health Study Exercise Questionnaire, indicating the frequency, type and duration of recreational PA in which they engaged at study enrollment. Metabolic equivalent (MET)-hours of weekly PA (MET-hrs/wk) were calculated using the Ainsworth Compendium. PA was dichotomized to 0-9 or 9+ MET-hrs/wk based on data in early stage breast cancer suggesting that women who engaged in &gt; 9 MET-hrs of PA/wk had lower cancer-specific mortality. Association with clinical endpoints was evaluated using multivariate Cox proportional hazard models adjusting for treatment assignment, age, tumor hormone-receptor status, prior taxane use, disease-free interval and visceral metastases.

Results: 799 patients enrolled in C40502 between 2008 and 2011. Baseline body mass index (BMI) was available for 792 patients and PA data for 500 participants. Median follow up was 60 months. Median age was 56.7 years; 72% of patients had hormone receptor (HR)-positive cancers. Median BMI was 28.6 kg/m2 (IQR: 24.7-33.1 kg/m2). Patients engaged in a median of 3.3 MET-hrs/wk of PA (about 1 hour of moderate-intensity PA/wk) (IQR: 0.7-12.7 MET-hrs/wk). Neither BMI nor PA was significantly associated with progression-free (PFS) or overall survival (OS).

BMI and OutcomesBMI (kg/m2)N (%)PFS (months)Adj HRP valueOS (months)Adj HRP value18.5-24.9209 (26.4)10.0 (9.1-11.2)ref0.4826.1 (23.3-33.2)ref0.5425-29.9248 (31.3)9.0 (7.6-10.3)1.00 (0.83-1.22) 22.0 (20.0-25.4)1.05 (0.85-1.30) ≥30335 (42.3)8.7 (7.7-9.7)0.97 (0.81-1.17) 25.5 (23.1-29.5)0.95 (0.78-1.16) 

PA and OutcomesPA (MET-hrs/wk)N (%)PFS (months)Adj HRP valueOS (months)Adj HRP value0-9344 (68.8)7.9 (7.4-9.2)ref0.1323.6 (20.1-26.8)ref0.21&gt;9156 (31.2)9.8 (8.9-12.0)0.86 (0.71-1.05) 27.4 (22.3-35.6)0.87 (0.70-1.08) 

There was a trend toward longer PFS and OS in patients who reported PA &gt; 9 MET-hrs/wk vs 0-9 MET-hrs/wk, especially in individuals with HR+ cancers (median PFS 11.7 vs 9.2 months [adj HR = 0.84 (0.66-1.05)] and OS 34.0 vs 26.5 months [adj HR = 0.83 (0.66-1.05)] with PA &gt;9 vs 0- 9 MET-hrs/wk).

Conclusions: In some of the first data looking at the relationship between lifestyle factors and outcomes in MBC, there was no relationship between BMI and PFS or OS in patients receiving first-line chemotherapy for advanced disease. A trend toward improved PFS and OS was seen in multivariate analysis in patients who reported higher levels of PA, but results were not statistically significant and could have been influenced by other patient factors. More information is needed regarding the relationship between PA and cancer outcomes, especially in patients with HR+ cancers.

Citation Format: Ligibel JA, Huebner LJ, Rugo HS, Burstein H, Toppmeyer DL, Anders CK, Ma C, Hudis CA, Winer EP, Barry WT. Physical activity, weight and outcomes in patients receiving first-line chemotherapy for metastatic breast cancer: Results from CALGB 40502 (Alliance) [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 P1-07-04.

Kinetic-Pharmacodynamic Model of Chemotherapy-Induced Peripheral Neuropathy in Patients with Metastatic Breast Cancer Treated with Paclitaxel, Nab-Paclitaxel, or Ixabepilone: CALGB 40502 (Alliance)

Chemotherapy-induced peripheral neuropathy (CIPN) is a dose-limiting toxicity caused by several chemotherapeutic agents. Currently, CIPN is managed by empirical dose modifications at the discretion of the treating physician. The goal of this research is to quantitate the dose-CIPN relationship to inform the optimal strategies for dose modification. Data were obtained from the Cancer and Leukemia Group B (CALGB) 40502 trial, a randomized phase III trial of paclitaxel vs. nab-paclitaxel vs. ixabepilone as first-line chemotherapy for locally recurrent or metastatic breast cancer. CIPN was measured using a subset of the Functional Assessment of Cancer Therapy-Gynecologic Oncology Group Neurotoxicity (FACT-GOG-NTX) scale. A kinetic-pharmacodynamic (K-PD) model was utilized to quantitate the dose-CIPN relationship simultaneously for the three drugs. Indirect response models with linear and Smax drug effects were evaluated. The model was evaluated by comparing the predicted proportion of patients with CIPN (score ≥8 or score ≥12) to the observed proportion. An indirect response model with linear drug effect was able to describe the longitudinal CIPN data reasonably well. The proportion of patients that were falsely predicted to have CIPN or were falsely predicted not to have CIPN was 20% or less at any cycle. The model will be utilized to identify an early time point that can predict CIPN at later time points. This strategy will be utilized to inform dose adjustments to prospectively manage CIPN. Clinicaltrials.gov ID: NCT00785291.

Prospective Validation of a 21-Gene Expression Assay in Breast Cancer

BACKGROUND

Prior studies with the use of a prospective-retrospective design including archival tumor samples have shown that gene-expression assays provide clinically useful prognostic information. However, a prospectively conducted study in a uniformly treated population provides the highest level of evidence supporting the clinical validity and usefulness of a biomarker.

METHODS

We performed a prospective trial involving women with hormone-receptor-positive, human epidermal growth factor receptor type 2 (HER2)-negative, axillary node-negative breast cancer with tumors of 1.1 to 5.0 cm in the greatest dimension (or 0.6 to 1.0 cm in the greatest dimension and intermediate or high tumor grade) who met established guidelines for the consideration of adjuvant chemotherapy on the basis of clinicopathologic features. A reverse-transcriptase-polymerase-chain-reaction assay of 21 genes was performed on the paraffin-embedded tumor tissue, and the results were used to calculate a score indicating the risk of breast-cancer recurrence; patients were assigned to receive endocrine therapy without chemotherapy if they had a recurrence score of 0 to 10, indicating a very low risk of recurrence (on a scale of 0 to 100, with higher scores indicating a greater risk of recurrence).

RESULTS

Of the 10,253 eligible women enrolled, 1626 women (15.9%) who had a recurrence score of 0 to 10 were assigned to receive endocrine therapy alone without chemotherapy. At 5 years, in this patient population, the rate of invasive disease-free survival was 93.8% (95% confidence interval [CI], 92.4 to 94.9), the rate of freedom from recurrence of breast cancer at a distant site was 99.3% (95% CI, 98.7 to 99.6), the rate of freedom from recurrence of breast cancer at a distant or local-regional site was 98.7% (95% CI, 97.9 to 99.2), and the rate of overall survival was 98.0% (95% CI, 97.1 to 98.6).

CONCLUSIONS

Among patients with hormone-receptor-positive, HER2-negative, axillary node-negative breast cancer who met established guidelines for the recommendation of adjuvant chemotherapy on the basis of clinicopathologic features, those with tumors that had a favorable gene-expression profile had very low rates of recurrence at 5 years with endocrine therapy alone. (Funded by the National Cancer Institute and others; ClinicalTrials.gov number, NCT00310180.).

Abstract P3-10-09: A Phase II trial of doxil, carboplatin and bevacizumab in metastatic triple negative breast cancer and molecular correlates of response

Background. Despite improved outcomes for other breast cancer subtypes, triple negative breast cancer continues to display the worst prognosis with conventional, standard of care chemotherapy. A growing body of evidence suggests that platinating agents may offer superior outcomes in a subset of triple negative breast cancers and that genomic alterations may identify those tumors most likely to respond.

Patients and Methods. Eligibility included previously untreated, stage IV ER, PgR, and Her2neu negative breast cancer with measurable disease. Thirty-one patients with ECOG PS≤2 and adequate bone marrow, renal and hepatic function were enrolled to receive doxil (30 mg/m2), carboplatin (AUC 5) and bevacizumab (15 mg/m2) every 4 weeks in an open-label, multicenter, investigator-initiated Phase II trial from 2008-2012. The primary endpoint was median progression free survival (PFS). Secondary endpoints were response rate based on RECIST criteria, survival time, and toxicity profile.

Results. Thirty-one patients received a median of 5.6 cycles (range 1-13). Prior adjuvant or neoadjuvant anthracycline or taxane was given in 38.7% or 41.9%, respectively. Clinical benefit rate (CBR= CR+PR+SD ≥ 6months) was 38.7% where 9/18 (50%) with CBR&lt;6 months and 4/13 (30.7%) with CBR&gt;6 months had prior taxane. Median progression free survival (PFS) was 5.6 months, 95% CI [4.4-6.9] and 6-month PFS rate was 41.9%, 95% CI [24.6-59.3]. Median overall survival was 11.9 months, 95% CI [8.8-21.8] and 1-year survival rate was 47.3%, 95% CI [29.5-65.1]. Thirteen patients were alive at 10 months or longer. Grade 3 non-hematologic and hematologic toxicities included fatigue (n=1), hand-foot skin reaction (n=1), and neutropenia (n=1). Grade 4 hematologic toxicity included thrombocytopenia (n=1). Grade 4 hypertension (n=2) and thrombosis (n=1) were attributable to bevacizumab and this drug was discontinued from the protocol. Neither significant change in cardiac function nor alopecia were observed. Next-generation sequencing from tumors revealed p53 alterations as the most common alteration. For three patients with serial pre- and post-platinum specimens, gain of genomic alterations were observed at time of progression of disease occurring at 5 months, 8 months, and 20 months (eight months of these were off study but receiving doxil and carboplatin).

Conclusions. Results demonstrate that the combination of doxil, carboplatin, and bevacizumab is an active and well-tolerated regimen in previously untreated, metastatic, triple negative breast cancer. We anticipated presentation of additional genomic tumor profiling results that may yield insights into markers of sensitivity and mechanism of resistance to anthracycline and/or platinum.

Citation Format: Kim M Hirshfield, Shou-En Lu, Serena Wong, Antoinette Tan, Laurie Kirstein, Thomas Kearney, Weichung Shih, Shridar Ganesan, Deborah L Toppmeyer. A Phase II trial of doxil, carboplatin and bevacizumab in metastatic triple negative breast cancer and molecular correlates of response [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P3-10-09.

Recurrence score and clinicopathologic characteristics of TAILORx participants by race and ethnicity

36

Background: Black race is associated with worse outcomes in localized breast cancer. We evaluated the characteristics of patients enrolled in the Trial Assigning Individualized Options for Treatment (TAILORx) by race and ethnicity. Methods: The analysis included 10,071 evaluable patients with Recurrence Score (RS) data. Eligibility criteria included: (1) T1-2, N0 disease, (2) estrogen receptor (ER) and/or progesterone receptor (PR) positive disease that was also HER2/neu negative, (3) age 75 years or younger and medically appropriate for adjuvant systemic chemotherapy. Results: The study population included 8,501 whites (84%), 722 blacks (7%), 423 Asians (4%), and the remainder other/unknown race. With regard to ethnicity, 7,916 were nonHispanic (79%), 919 were Hispanic (9%), and 1,236 were of unreported ethnicity (12%). There was no significant difference in RS distribution (p = 0.14), median RS (17 vs. 17), and mean RS (19.6 vs. 18.4) in blacks compared with nonblacks. There was likewise no difference in Hispanic vs. nonHispanic ethnicity for RS distribution (p = 0.53), median RS (17 vs. 17), and mean RS (18.6 vs. 18.4). Blacks were significantly more likely to be younger (39% vs. 30% < 50 years), have larger tumors (37% vs. 31% > 2 cm), poor histologic grade (25% vs. 17%), and PR-negative disease (14% vs. 10%) (Chi square test p < 0.05). Hispanic women were also significantly younger (39% vs. 30% < 50 years), and demonstrated marginal but statistically significant differences in tumor size (65% vs. 69% > 2 cm), histologic grade (20% vs. 18% poor), and PR expression (12% vs. 10% negative) (Chi square test < 0.05). In 974 patients with information on body mass index (BMI), there was no correlation between BMI and RS (r = -0.04). BMI was higher for blacks than whites (medians 31.6 vs. 28.9, p = 0.02, Wilcoxon test), but not in Hispanics. Conclusions: In patients selected for participation in TAILORx there were no significant differences in RS by race, ethnicity, and BMI. Black and Hispanic patients were significantly younger, and blacks had tumors that were larger and more likely to be associated with poor grade. Clinical trial information: NCT00310180.

Metabotropic glutamate receptor 1 expression and its polymorphic variants associate with breast cancer phenotypes

Several epidemiological studies have suggested a link between melanoma and breast cancer. Metabotropic glutamate receptor 1 (GRM1), which is involved in many cellular processes including proliferation and differentiation, has been implicated in melanomagenesis, with ectopic expression of GRM1 causing malignant transformation of melanocytes. This study was undertaken to evaluate GRM1 expression and polymorphic variants in GRM1 for associations with breast cancer phenotypes. Three single nucleotide polymorphisms (SNPs) in GRM1 were evaluated for associations with breast cancer clinicopathologic variables. GRM1 expression was evaluated in human normal and cancerous breast tissue and for in vitro response to hormonal manipulation. Genotyping was performed on genomic DNA from over 1,000 breast cancer patients. Rs6923492 and rs362962 genotypes associated with age at diagnosis that was highly dependent upon the breast cancer molecular phenotype. The rs362962 TT genotype also associated with risk of estrogen receptor or progesterone receptor positive breast cancer. In vitro analysis showed increased GRM1 expression in breast cancer cells treated with estrogen or the combination of estrogen and progesterone, but reduced GRM1 expression with tamoxifen treatment. Evaluation of GRM1 expression in human breast tumor specimens demonstrated significant correlations between GRM1 staining with tissue type and molecular features. Furthermore, analysis of gene expression data from primary breast tumors showed that high GRM1 expression correlated with a shorter distant metastasis-free survival as compared to low GRM1 expression in tamoxifen-treated patients. Additionally, induced knockdown of GRM1 in an estrogen receptor positive breast cancer cell line correlated with reduced cell proliferation. Taken together, these findings suggest a functional role for GRM1 in breast cancer.

Polymorphic variants in TSC1 and TSC2 and their association with breast cancer phenotypes

TSC1 acts coordinately with TSC2 in a complex to inhibit mTOR, an emerging therapeutic target and known promoter of cell growth and cell cycle progression. Perturbation of the mTOR pathway, through abnormal expression or function of pathway genes, could lead to tumorigenesis. TSC1 and TSC2 expression is reduced in invasive breast cancer as compared with normal mammary epithelium. Because single nucleotide polymorphisms (SNPs) in regulatory genes have been implicated in risk and age at diagnosis of breast cancers, systematic SNP association studies were performed on TSC1 and TSC2 SNPs for their associations with clinical features of breast cancer. TSC1 and TSC2 haplotypes were constructed from genotyping of multiple loci in both genes in healthy volunteers. SNPs were selected for further study using a bioinformatics approach based on SNP associations with drug response in NCI-60 cell lines and evidence of selection bias based on haplotype frequencies. Genotyping for five TSC1 and one TSC2 loci were performed on genomic DNA from 1,137 women with breast cancer. This study found that for TSC1 rs7874234, TT variant carriers had a 9-year later age at diagnosis of estrogen receptor positive (ER+), but not ER-, ductal carcinomas (P = 0.0049). No other SNP locus showed an association with age at diagnosis, nor any other breast cancer phenotype. TSC1 rs7874234 is hypothesized to be functional in ER+ breast cancer because the T allele, but not the C allele, may create an estrogen receptor element (ERE) site, resulting in increased TSC1 transcription and subsequent inhibition of mTOR.

A polymorphic variant in human MDM4 associates with accelerated age of onset of estrogen receptor negative breast cancer

Murine double minute 4 (MDM4) shares significant structural homology with murine double minute 2 (MDM2) and interacts and regulates transcriptional activity of the tumor suppressor p53. In tumors with wild-type p53, there is often overexpression of MDM2 or MDM4 leading to functional inactivation of p53. A single-nucleotide polymorphism (SNP) in the promoter of human MDM2 (SNP309) was shown to associate with increased MDM2 expression and increased risk of cancer. This study evaluated the association of a SNP in human MDM4 (C>T) with age of onset of breast cancer in two independent cohorts. In cohort 1 of 675 patients, the average age of diagnosis for women with estrogen receptor (ER)-positive and ER-negative breast cancers was 53.2 and 48 years, respectively. In this cohort, homozygous variant (TT) carriers developed ER-negative carcinomas at an earlier age than homozygous wild-type (CC) or heterozygous (TC) such that the age at diagnosis was accelerated by 5.0 years (P = 0.018). This association was validated in a second cohort of breast cancer patients (n = 148), where TT carriers with ER-negative cancer developed the disease 3.8 years earlier than CC carriers (P = 0.006). The effect was more pronounced in Caucasians with ER-negative ductal carcinomas with TT homozygotes developing disease 7.5 years (P = 0.031) and 6.2 years (P = 7 x 10(-5)) earlier than CC carriers in cohorts 1 and 2, respectively. No association was seen in ER-positive ductal cancers suggesting that the SNP in MDM4 only has a functional association in ER-negative breast cancer.

A phase I and pharmacologic study of the combination of marimastat and paclitaxel in patients with advanced malignancy

BACKGROUND

Marimastat is a potent inhibitor of matrix metalloproteinases and in preclinical studies enhances the anti-tumor activity of certain chemotherapeutics. We performed a phase I clinical evaluation of the combination of oral marimastat and intravenous paclitaxel, to determine if these drugs could be co-administered safely, and to determine whether marimastat alters paclitaxel pharmacokinetics.

MATERIAL/METHODS

Marimastat was administered twice daily and paclitaxel as a three hour infusion every three weeks. Doses of both marimastat and paclitaxel were escalated in cohorts of patients up to maximal doses of 10 mg for marimastat and 175 mg/m2 for paclitaxel. Paclitaxel plasma pharmacokinetic parameters were assessed in the absence (cycle 1) and presence (cycle 2) of marimastat. Trough marimastat plasma levels were evaluated during cycle 2.

RESULTS

A total of 19 patients were treated at three different dose levels. There were no dose-limiting toxicities during the first cycle of therapy, resulting in dose escalation up to the planned maximal dose for each drug. Neutropenia was the most common significant toxicity at the highest dose level, with grade 3 or higher neutropenia occurring in 38% of patients. There were no complete or partial responses. Pharmacokinetic analyses indicate that marimastat does not alter paclitaxel clearance. At the 10 mg dose, the mean trough marimastat level was 14.8 Kg/L.

CONCLUSIONS

Marimastat and paclitaxel can be co-administered safely at doses equivalent to those recommended for single-agent administration. Additional studies are necessary to determine whether this combination is more effective in controlling tumor progression than paclitaxel alone.

Central nervous system progression during systemic response to trastuzumab, humanized anti-HER-2/neu antibody, plus paclitaxel in a woman with refractory metastatic breast cancer

Treatment of selected patients with anti-HER-2/neu antibodies alone (1) or in combination with chemotherapy (2) may be of benefit to patients with refractory breast cancer. Approximately 30% of breast cancers overexpress HER-2/neu, a member of the epidermal growth factor receptor family. These patients may have a poorer overall prognosis (3) due to relative resistance to both hormonal therapy and chemotherapy (4-6). We recently observed a patient with refractory breast cancer who responded to rhuMAB HER-2 (trastuzumab) plus paclitaxel after progressing on paclitaxel alone. While on combination treatment she developed cerebellar metastases. Follow-up computed tomography (CT) scan revealed that her disease continued to respond in the liver, lungs, and bone. This case suggests that failure of trastuzumab to cross the blood-brain barrier may compromise its overall effectiveness and raises the possibility that the central nervous system (CNS), or other sanctuary sites, may become clinically more significant in patients with breast cancer in the era of antibody-based therapies.

A phase I trial of a potent P-glycoprotein inhibitor, Zosuquidar.3HCl trihydrochloride (LY335979), administered orally in combination with doxorubicin in patients with advanced malignancies

PURPOSE

The purpose of this study was to investigate the safety and tolerability of Zosuquidar.3HCl, a potent inhibitor of P-glycoprotein (Pgp), when administered p.o. alone and in combination with doxorubicin and to determine whether Zosuquidar.3HCl affects doxorubicin pharmacokinetics and inhibits Pgp function in peripheral blood natural killer lymphocytes.

EXPERIMENTAL DESIGN

Patients with advanced nonhematological malignancies were eligible for this Phase I trial. Zosuquidar.3HCl and doxorubicin were administered separately during the first cycle of therapy and then administered concurrently. Zosuquidar.3HCl was administered over 4 days, with doses escalated until the occurrence of dose-limiting toxicity. Subsequently, doxorubicin doses were increased from 45 to 75 mg/m(2). Zosuquidar.3HCl, doxorubicin, and doxorubicinol pharmacokinetics were analyzed, and dual fluorescence cytometry was used to determine the effects of Zosuquidar.3HCl on Pgp function in natural killer cells.

RESULTS

A total of 38 patients were treated at nine dose levels. Neurotoxicity was dose-limiting for oral Zosuquidar.3HCl, characterized by cerebellar dysfunction, hallucinations, and palinopsia. The maximum-tolerated dose for oral Zosuquidar.3HCl administered every 12 h for 4 days is 300 mg/m(2). Zosuquidar.3HCl did not affect doxorubicin myelosuppression or pharmacokinetics, and Zosuquidar.3HCl pharmacokinetics were similar in the absence and presence of doxorubicin. Higher plasma concentrations of Zosuquidar.3HCl were associated with greater Pgp inhibition in natural killer cells.

CONCLUSION

Zosuquidar.3HCl can be coadministered with doxorubicin using a 4-day oral dosing schedule, with little effect on doxorubicin toxicity or pharmacokinetics. Further refinement in Zosuquidar.3HCl dosing and scheduling should be explored to optimize Pgp inhibition while minimizing cerebellar toxicity.

Phase I and pharmacokinetic study of LU79553, a DNA intercalating bisnaphthalimide, in patients with solid malignancies

PURPOSE

To determine the maximum-tolerated dose and characterize the pharmacokinetic behavior of LU79553, a novel bisnaphthalimide antineoplastic agent, when administered as a daily intravenous infusion for 5 days every 3 weeks.

PATIENTS AND METHODS

Patients with advanced solid malignancies received escalating doses of LU79553. Plasma sampling and urine collections were performed on both days 1 and 5 of the first course.

RESULTS

Thirty patients received 105 courses of LU79553 at doses ranging from 2 to 24 mg/m(2)/d. Proximal myopathy, erectile dysfunction, and myelosuppression precluded the administration of multiple courses at doses above 18 mg/m(2)/d. These toxicities were intolerable in two of six patients after receiving three courses at the 24-mg/m(2)/d dose level. At the 18-mg/m(2)/d dose, one of six patients developed febrile neutropenia and grade 2 proximal myopathy after three courses of LU79553. The results of electrophysiologic, histopathologic, and ultrastructural studies supported a drug-induced primary myopathic process. A patient with a platinum- and taxane-resistant papillary serous carcinoma of the peritoneum experienced a partial response lasting 22 months. Pharmacokinetics were dose-independent, optimally described by a three-compartment model, and there was modest drug accumulation over the 5 days of treatment.

CONCLUSION

Although no dose-limiting events were noted in the first two courses of LU79553, cumulative muscular toxicity precluded repetitive treatment with LU79553 at doses above 18 mg/m(2)/d, which is the recommended dose for subsequent disease-directed evaluations. The preliminary antitumor activity noted is encouraging, but the qualitative and cumulative nature of the principal toxicities, as well as the relatively small number of patients treated repetitively, mandate that rigorous and long-term toxicologic monitoring be performed in subsequent evaluations of this unique agent.

Overexpression of the multidrug resistance-associated protein (MRP) gene in vincristine but not doxorubicin-selected multidrug-resistant murine erythroleukemia cells

Multidrug-resistant sublines of the murine erythroleukemia cell line PC4 were sequentially selected in increasing vincristine concentrations (5-160 ng/ml). The low- and intermediate-level resistant cell lines, selected in < or = 40 ng/ml of vincristine, demonstrated resistance to Vinca alkaloids and to an epipodophyllotoxin but little or none to an anthracycline. The expression of murine mdr genes, as analyzed by Northern blotting, revealed a baseline expression of murine mdr2 in parental cells that was unchanged in the drug-resistant cell lines. Overexpression of mdr3 was observed only in the highest-level resistant cell line, PC-V160, whereas mdr1 mRNA was not detected in any of the cell lines. The polymerase chain reaction, using mdr3-specific primers, excluded the possibility that low levels of P-glycoprotein expression contributed to the resistance phenotype in the low and intermediate-level resistant cell lines. Northern blot analysis using a human complementary DNA probe for the multidrug resistance-associated protein (MRP) demonstrated overexpression of murine mrp in each of the vincristine-selected sublines. Genomic amplification of the mrp gene was coincident with mrp overexpression. The expression of mrp was also examined in two series of previously characterized doxorubicin-selected cell lines derived from parental PC4 and C7D murine erythroleukemia cells. In contrast to the vincristine-selected cell lines, overexpression of mrp was not detected. These studies demonstrate that, in murine erythroleukemia cells selected for vincristine resistance, overexpression of murine mrp occurred prior to that for murine mdr. In contrast to human MRP, selection for vincristine, but not doxorubicin resistance, resulted in the overexpression of murine mrp.

Role of P-glycoprotein in dolastatin 10 resistance

Dolastatin 10, a cytotoxic pentapeptide isolated from the mollusk Dolabella auricularia, exhibits potent antitumor activity. The present studies demonstrated that sublines of murine PC4 and human U-937 leukemia cells expressing a multidrug resistance (MDR) phenotype are cross-resistant to this agent. We also demonstrated that such resistance was reversed by verapamil. While these findings suggested the involvement of the P-glycoprotein (P-gp) in dolastatin 10 resistance, we performed similar studies in a CHO cell line transfected with the human mdr1 cDNA. Expression of P-gp in the transfected cells was associated with resistance to dolastatin 10 by a verapamil-sensitive mechanism. The demonstration that photoaffinity labeling of P-gp was decreased in the presence of dolastatin 10 further supports the interaction of this cytotoxic peptide with P-gp. Taken together, these findings suggest that resistance to dolastatin 10 is conferred, at least in part, by P-gp and that this cytotoxic peptide is a novel member of the MDR phenotype.

Plasma cell-regulated polyadenylation at the Ig gamma 2b secretion-specific poly(A) site

We found that the sequences downstream of the Ig gamma 2b secretory-specific (sec) poly(A) site play an important role in the preferential production of sec Ig mRNA during plasma B cell development. The Ig gamma 2b mRNA production in a deletion mutant (delta-Kpn) lacking the Ig sec poly(A) site and downstream consensus element (dsc) has been previously shown to default to the use of the downstream membrane-specific (mb) poly(A) site. In this study restoration of the Ig sec poly(A) site and dsc to the delta-Kpn gene causes a significant increase in the use of the sec poly(A) site vs mb poly(A) site in stable transfectants of plasma but not memory B cell tumors, indicating plasma cell-specific recognition of the Ig sec dsc. Restoration of the poly(A) cleavage site alone to delta-Kpn did not restore regulation. Substitution of an SV40 downstream poly(A) element for the Ig dsc in the delta-Kpn gene also does not restore regulation. The data further indicate that although the Ig dsc is clearly very important in the plasma cell-regulated expression, the difference in the processing ratios of the restored vs the intact Ig gamma 2b gene in plasma cells suggests that there are other yet to be defined sequences that may also play a role in the intact gene. Insertion of a 130-nucleotide segment of the gene containing the Ig sec poly(A) site and dsc into a heterologous, guanosyl phosphotransferase gene resulted in plasma cell-regulated polyadenylation of the sec poly(A) site. Neither the mb nor the SV40 early poly(A) sites and their respective dscs, in similar gpt chimeras, were regulated. Therefore the region downstream of the Ig sec poly(A) site plays an essential role in regulating polyadenylation at the sec poly(A) site in plasma cells but not memory cells. A model involving a plasma cell-specific recognition factor for the Ig sec dsc is presented.

Plasma cell-regulated polyadenylation at the Ig gamma 2b secretion-specific poly(A) site

We found that the sequences downstream of the Ig gamma 2b secretory-specific (sec) poly(A) site play an important role in the preferential production of sec Ig mRNA during plasma B cell development. The Ig gamma 2b mRNA production in a deletion mutant (delta-Kpn) lacking the Ig sec poly(A) site and downstream consensus element (dsc) has been previously shown to default to the use of the downstream membrane-specific (mb) poly(A) site. In this study restoration of the Ig sec poly(A) site and dsc to the delta-Kpn gene causes a significant increase in the use of the sec poly(A) site vs mb poly(A) site in stable transfectants of plasma but not memory B cell tumors, indicating plasma cell-specific recognition of the Ig sec dsc. Restoration of the poly(A) cleavage site alone to delta-Kpn did not restore regulation. Substitution of an SV40 downstream poly(A) element for the Ig dsc in the delta-Kpn gene also does not restore regulation. The data further indicate that although the Ig dsc is clearly very important in the plasma cell-regulated expression, the difference in the processing ratios of the restored vs the intact Ig gamma 2b gene in plasma cells suggests that there are other yet to be defined sequences that may also play a role in the intact gene. Insertion of a 130-nucleotide segment of the gene containing the Ig sec poly(A) site and dsc into a heterologous, guanosyl phosphotransferase gene resulted in plasma cell-regulated polyadenylation of the sec poly(A) site. Neither the mb nor the SV40 early poly(A) sites and their respective dscs, in similar gpt chimeras, were regulated. Therefore the region downstream of the Ig sec poly(A) site plays an essential role in regulating polyadenylation at the sec poly(A) site in plasma cells but not memory cells. A model involving a plasma cell-specific recognition factor for the Ig sec dsc is presented.