Symptomatic Necrosis With Antibody-Drug Conjugates and Concurrent Stereotactic Radiotherapy for Brain Metastases

This cohort study investigates whether brain metastases that manifest after stereotactic radiotherapy with concurrent antibody-drug conjugates are associated with an increased risk of symptomatic radiation necrosis.

New strategies for the treatment of breast cancer with leptomeningeal metastasis

PURPOSE OF REVIEW

Leptomeningeal metastasis is a complication of metastatic breast cancer that has a rising incidence likely due to the increased availability of novel systemic therapies, which have improved survival with better extracranial disease control but with limited intracranial efficacy. A poor prognosis of less than 6 months has historically been associated with leptomeningeal metastasis and it is often an exclusion factor for enrollment in clinical trials. There are limited evidence-based data supporting use of therapeutics in leptomeningeal metastasis patients and recommendations are largely derived from retrospective reports and small prospective studies. However, in recent years, there has been a surge in effective modern therapeutics with promising intracranial activity.

RECENT FINDINGS

The study aims to review the most recent updates in the management of leptomeningeal metastasis in breast cancer. We discuss the effectiveness and limitations of intrathecal administration, predictive biomarkers in the cerebrospinal fluid, proton radiation therapy and promising new systemic therapies such as antibody drug conjugates.

SUMMARY

Ongoing development of clinical trials that allow inclusion of leptomeningeal metastasis are essential for establishing efficacy potential and discovering new treatment options in this population of great unmet need.

Incidence of HER2-expressing brain metastases in patients with HER2-null breast cancer: a matched case analysis

The HER2-directed antibody-drug conjugate trastuzumab deruxtecan is active against lower levels of HER2 expression than prior-generation therapies. The rate of HER2 expression in brain metastases among patients with initially HER2-null breast cancer is undefined, and receptor discordance in advanced breast cancer with brain metastases may underestimate CNS response potential in the absence of brain metastasis sampling. In this cohort study including 136 patients with 401 samples scored according to ASCO/CAP guidelines, 15/28 patients (54%) with HER2-null primary breast cancer have detectable HER2 expression in subsequently resected brain metastases, a significant discordant population.

Intrathecal trastuzumab versus alternate routes of delivery for HER2-targeted therapies in patients with HER2+ breast cancer leptomeningeal metastases

BACKGROUND

Patients with HER2+ breast cancer (BC) frequently develop leptomeningeal metastases (LM). While HER2-targeted therapies have demonstrated efficacy in the neoadjuvant, adjuvant, and metastatic settings, including for parenchymal brain metastases, their efficacy for patients with LM has not been studied in a randomized controlled trial. However, several single-armed prospective studies, case series and case reports have studied oral, intravenous, or intrathecally administered HER2-targeted therapy regimens for patients with HER2+ BC LM.

METHODS

We conducted a systematic review and meta-analysis of individual patient data to evaluate the efficacy of HER2-targeted therapies in HER2+ BC LM in accordance with PRISMA guidelines. Targeted therapies evaluated were trastuzumab (intrathecal or intravenous), pertuzumab, lapatinib, neratinib, tucatinib, trastuzumab-emtansine and trastuzumab-deruxtecan. The primary endpoint was overall survival (OS), with CNS-specific progression-free survival (PFS) as a secondary endpoint.

RESULTS

7780 abstracts were screened, identifying 45 publications with 208 patients, corresponding to 275 lines of HER2-targeted therapy for BC LM which met inclusion criteria. In univariable and multivariable analyses, we observed no significant difference in OS and CNS-specific PFS between intrathecal trastuzumab compared to oral or intravenous administration of HER2-targeted therapy. Anti-HER2 monoclonal antibody-based regimens did not demonstrate superiority over HER2 tyrosine kinase inhibitors. In a cohort of 15 patients, treatment with trastuzumab-deruxtecan was associated with prolonged OS compared to other HER2-targeted therapies and compared to trastuzumab-emtansine.

CONCLUSIONS

The results of this meta-analysis, comprising the limited data available, suggest that intrathecal administration of HER2-targeted therapy for patients with HER2+ BC LM confers no additional benefit over oral and/or IV treatment regimens. Although the number of patients receiving trastuzumab deruxtecan in this cohort is small, this novel agent offers promise for this patient population and requires further investigation in prospective studies.

Impact of prior systemic therapy on lymphocytic infiltration in surgically resected breast cancer brain metastases

PURPOSE

Tumor-infiltrating lymphocytes (TILs) have been positively correlated with response to systemic therapy for triple-negative and HER2 + subtypes and improved clinical outcomes in early breast cancer (BC). Less is known about TILs in metastatic sites, particularly brain metastases (BM), where unique immune regulation governs stromal composition. Reactive glial cells actively participate in cytokine-mediated T cell stimulation. The impact of prior medical therapy (chemotherapy, endocrine, and HER2-targeted therapy) on the presence of TILs and gliosis in human breast cancer brain metastases (BCBM) has not been previously reported.

METHODS

We examined prior treatment data for 133 patients who underwent craniotomy for resection of BMs from the electronic medical record. The primary endpoint was overall survival (OS) from the time of BM diagnosis. We examined the relationship between prior systemic therapy exposure and the histologic features of gliosis, necrosis, hemorrhage, and lymphocyte infiltration (LI) in BCBMs resected at subsequent craniotomy in univariate analyses.

RESULTS

Complete treatment data were available for 123 patients. BCBM LI was identified in 35 of 116 (30%) patients who had received prior systemic treatment versus 5 of 7 (71.4%) who had not {significant by Fisher's exact test p = 0.045}. There were no statistically significant relationships between prior systemic therapy and the three other histologic variables examined.

CONCLUSIONS

This observation suggests that systemic therapy may interfere with the immune response to BCBMs and cause exhaustion of anti-tumor immunity. This motivates clinical investigation of strategies to enhance LI for therapeutic benefit to improve outcomes for patients with BCBMs.

Abstract P4-01-09: Characterization of breast cancer brain metastases overall and progression-free survival and timing of cyclin-dependent kinase 4/6 inhibitor use: Retrospective single institution experience

Background Approximately 15% of patients (pts) with hormone receptor (HR)+ human epidermal growth factor receptor 2 (HER2)- breast cancer will develop brain metastases (BM) (Kuksis et al, NeuroOnc 2021). Cyclin dependent kinase 4/6 inhibitors (CDK4/6i) with an endocrine therapy partner are recommended 1st line treatments in HR+HER2- metastatic breast cancer (MBC). Preclinical models show that CDK4/6i can cross the blood brain barrier (BBB). In vitro assays have shown that abemaciclib crosses the BBB more effectively than palbociclib or ribociclib (George et al, Front Oncol 2021). The efficacy of CDK4/6i in patients with breast cancer BM is not well described. Methods We examined prior treatment data for 368 pts with HR+HER2- BM who received a CDK4/6i between 2015 to 2021. The primary endpoint was overall survival (OS) from the time of starting CDK4/6i after BM development. CNS progression free survival (PFS) was assessed in pts who received CDK4/6i after BM development. We examined the relationship between OS, type and timing of CDK4/6i in multivariate analyses. Statistical analyses were conducted using R 4.1.2 software. Results Of the total cohort of 368 pts, 23% (n=86) had de novo MBC and 77% (n=282) had relapsed MBC. At initial presentation of MBC 79% (n=290) of pts had no BM, 19% (n=71) had BM and extracranial disease and 2% (n=7) had BM only. 56% (n=205) received a CDK4/6i before BM development, 37% (n=136) received a CDK4/6i after BM development and 7% (n=27) received a CDK 4/6i both before and after BM development. The most common CDK4/6i used first was palbociclib (85%, n=312) followed by abemaciclib (13%, n=47) and ribociclib (2%, n=9). At the time of data cutoff 277 pts were dead, 55 were alive and 36 were lost to follow up. The median follow-up of surviving pts from BM development was 32 months. 163 pts received a CDK4/6i post BM: palbociclib (66%, n=108), abemaciclib (31%, n=51) and ribociclib (3%, n=4). Of these 163 pts 83% (n=136) received a CDK4/6i as their 1st or 2nd systemic treatment post BM. In the cohort of 163 pts who received a CDK4/6i post BM, 9% did not receive local BM therapy, 40% had whole brain radiotherapy (WBRT), 34% had stereotactic surgery (SRS) alone and 17% had surgery +/- SRS. The median CNS PFS for pts who received a CDK4/6i after BM was 21 months with palbociclib and 14 months with abemaciclib (p value 0.11). Too few pts received ribociclib for analysis. CNS PFS was 21 months for pts receiving a CDK4/6i only after BM development and 10 months for those who received CDK4/6i both before and after BM diagnosis (p = 0.01). Pts who died prior to CNS progression were censored. Median OS from the time of starting CDK4/6i after BM development for pts receiving a CDK4/6i only after BM development was 25 months versus 12 months for those who received it both before and after BM development (p = 0.03). There was no statistically significant difference in OS when adjusting for the type of local BM treatment received, time from initial MBC diagnosis to BM, or the Breast Graded Prognostic Assessment (GPA) score (Sperduto et al, IJROBP 2020). Conclusions This observation suggests that there is a greater OS benefit from the time of starting CDK4/6i after BM development in pts who receive CDK4/6i solely after BM development compared to pts who received a CDK4/6i both before and after BM development. This is not unexpected given the known OS benefit associated with early use of these agents. Our unique observation of longer CNS PFS for patients who did not receive CDK4/6i prior to BM but who received it afterward suggests that CDK4/6i exposure prior to BM development may lead to development of resistance mechanisms that reduces CNS efficacy upon rechallenging with CDK4/6i after BM development. There was no statistically significant difference in post-BM CNS PFS by type of CDK4/6i received. This motivates investigation of biomarkers for patient selection and our ongoing work in collecting a matched comparison cohort of HR+HER2- pts with BM who never received CDK4/6i.

Citation Format: Sonya Chew Minmin, Yuan Chen, Daniel Kelly, Mark E. Robson, Andrew D Seidman. Characterization of breast cancer brain metastases overall and progression-free survival and timing of cyclin-dependent kinase 4/6 inhibitor use: Retrospective single institution experience [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P4-01-09.

Abstract P4-02-14: Gain of HER2 Amplification in Patients with HR+/HER2- and Triple Negative Early Breast Cancer Treated with Neoadjuvant Chemotherapy

Background: Neoadjuvant chemotherapy (NAC) is standard of care for the majority of patients with clinical stage II-III triple negative breast cancer (TNBC) and is considered in high-risk patients with hormone receptor positive (HR+)/human epidermal growth factor receptor 2 (HER2) negative (-) tumors, with expected pathological complete response (pCR) rates of 40-60% and 10-12%, respectively. In HER2- patients with residual disease (RD) after NAC, there is limited data on rates of gain of HER2 amplification. The biological and clinical significance of this phenomenon is unknown and determining the best adjuvant therapy for these patients remains a challenge. We sought to determine the rate of HER2 gain in a cohort of consecutive patients with HER2- breast cancer (BC) treated with NAC.

Methods: From 01/2021 to 12/2021, we identified patients with HER2- breast cancer treated with NAC followed by surgery at our institution. Patients who received neoadjuvant endocrine therapy were excluded. The rates of pCR (ypT0/is ypN0) and HER2 status pre- and post-NAC were assessed. Estrogen receptor (ER), progesterone receptor (PR) and HER2 status on surgery specimens were internally determined for all patients using ASCO/CAP 2020 guidelines. ER-low was defined as ER expression by immunohistochemistry (IHC) 1-10%.

Results: We included 256 patients, 130 (51%) HR+/HER2- [13/130(10%) ER-low] and 126 (49%) TNBC. Median age was 48 years (range 25-82) and the majority presented with clinical T2 (57%) and N1 (59%). Of 130 patients with HR+/HER2-tumors, 120 (92%) received dose-dense (dd) doxorubicin/cyclophosphamide-paclitaxel (AC-T). Of 126 TNBC patients, 46 (37%) received ddAC followed by carboplatin in combination with paclitaxel +/- pembrolizumab. Centralized HER2 status assessment on the core biopsy was performed in 22% of samples. Overall, pCR was achieved in 40% of TNBC and 11% of HR+/HER2-. Among the 192 patients with RD, the rate of HER2 gain was 8/192 (4%), including 3% (2/76) of TNBC and 5% (6/116) of HR+/HER2- patients. 7 of the 8 patients (88%) converted from IHC 1+ or 2+ fluorescence in situ hybridization (FISH) not amplified on core biopsy to IHC 2+ FISH amplified on the surgical specimen. In only 1 case, the HER2 status converted from IHC2+ FISH not amplified to IHC3+. 3/8 patients had multifocal disease. All 6 patients with HR+/HER2- BC and HER2 gain had high (>90%) ER expression (Table 1). All but one patient with HER2 gain received adjuvant anti-HER2 therapy. After a median follow-up of 10 months, no recurrence events occurred in this group.12 of the remaining 184 patients experienced a recurrence [11 distant recurrences (8 and 3, in the TNBC and HR+/HER2- groups, respectively), and there was 1 local event (localized chest wall recurrence) in the HR+/HER2- group].

Conclusions: At a single center, we found that in patients with HER2- BC treated with NAC, HER2 gain in patients with RD was uncommon and occurred more frequently in those with HR+ tumors. Analysis of a larger cohort is ongoing to corroborate these results. It is remains to be determined if this phenomenon represents a true HER2 status conversion or tumor heterogeneity.

Table 1: Clinico-pathological characteristics of patients with HER2 gain on residual disease

Citation Format: Emanuela Ferraro, Sonya Chew Minmin, Anton Safonov, Andrea V. Barrio, Shanu Modi, Andrew D Seidman, Hanna Y Wen, Edi Brogi, Mark E. Robson, Chau T Dang. Gain of HER2 Amplification in Patients with HR+/HER2- and Triple Negative Early Breast Cancer Treated with Neoadjuvant Chemotherapy [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P4-02-14.

Breast Cancer Brain Metastases: Achilles' Heel in Breast Cancer Patients' Care

Brain metastases (BM) significantly affect the prognosis as well as the quality of life of breast cancer (BC) patients. Although advancements in neurosurgical and radiotherapy techniques improve local control and symptom management, BM remains associated with a poor prognosis. In addition, the efficacy of currently approved systemic therapies in central nervous system (CNS) compartment is still limited, especially after progression on local therapy. The blood-brain barrier (BBB) has been recognized as a mechanism of primary resistance to many chemotherapeutic agents and targeted therapies due to low drug penetration. Other mechanisms of primary and secondary resistance are still unclear and may vary across the BC subtypes. New small molecules have demonstrated efficacy in BM, in particular for the HER2-positive subtype, with a benefit in survival. A new era has begun in the field of BM, and many trials specifically designed for this population are currently ongoing. The BC research community needs to address this call with the final aim of improving the efficacy of systemic therapy in CNS compartment and ultimately preventing the occurrence of BM.

Randomized Phase II Trial of Proton Craniospinal Irradiation Versus Photon Involved-Field Radiotherapy for Patients With Solid Tumor Leptomeningeal Metastasis

PURPOSE

Photon involved-field radiotherapy (IFRT) is the standard-of-care radiotherapy for patients with leptomeningeal metastasis (LM) from solid tumors. We tested whether proton craniospinal irradiation (pCSI) encompassing the entire CNS would result in superior CNS progression-free survival (PFS) compared with IFRT.

PATIENTS AND METHODS

We conducted a randomized, phase II trial of pCSI versus IFRT in patients with non-small-cell lung cancer and breast cancers with LM. We enrolled patients with other solid tumors to an exploratory pCSI group. For the randomized groups, patients were assigned (2:1), stratified by histology and systemic disease status, to pCSI or IFRT. The primary end point was CNS PFS. Secondary end points included overall survival (OS) and treatment-related adverse events (TAEs).

RESULTS

Between April 16, 2020, and October 11, 2021, 42 and 21 patients were randomly assigned to pCSI and IFRT, respectively. At planned interim analysis, a significant benefit in CNS PFS was observed with pCSI (median 7.5 months; 95% CI, 6.6 months to not reached) compared with IFRT (2.3 months; 95% CI, 1.2 to 5.8 months; P < .001). We also observed OS benefit with pCSI (9.9 months; 95% CI, 7.5 months to not reached) versus IFRT (6.0 months; 95% CI, 3.9 months to not reached; P = .029). There was no difference in the rate of grade 3 and 4 TAEs (P = .19). In the exploratory pCSI group, 35 patients enrolled, the median CNS PFS was 5.8 months (95% CI, 4.4 to 9.1 months) and OS was 6.6 months (95% CI, 5.4 to 11 months).

CONCLUSION

Compared with photon IFRT, we found pCSI improved CNS PFS and OS for patients with non-small-cell lung cancer and breast cancer with LM with no increase in serious TAEs.

Treatment With Etirinotecan Pegol for Patients With Metastatic Breast Cancer and Brain Metastases: Final Results From the Phase 3 ATTAIN Randomized Clinical Trial

Importance

Patients with breast cancer and brain metastases (BM) have a poor prognosis and high clinical need for novel treatments; however, historically, studies have often excluded these patients. Although the BEACON study did not meet its primary end point, treatment with etirinotecan pegol vs chemotherapy of the physician's choice for patients with advanced breast cancer demonstrated a significant improvement in overall survival (OS) for the prespecified patient subgroup with preexisting, pretreated, and nonprogressive BM.

Objective

To compare clinical outcomes in patients with BM treated with etirinotecan pegol vs chemotherapy of the physician's choice in a confirmatory trial.

Design, Setting, and Participants

This study was a phase 3, open-label, randomized clinical trial (ATTAIN) in patients with metastatic breast cancer and a history of stable pretreated BM who experienced disease progression while receiving chemotherapy in the metastatic setting. The trial took place at 47 sites in 10 countries, and patients were enrolled between March 7, 2017, and November 6, 2019.

Interventions

Patients were randomized to receive etirinotecan pegol, 145 mg/m2, every 21 days or chemotherapy (eribulin, ixabepilone, vinorelbine, gemcitabine, paclitaxel, docetaxel, or nab-paclitaxel).

Main Outcomes and Measures

The primary end point was OS. Key secondary end points included progression-free survival, objective response rate, duration of response, and the clinical benefit rate.

Results

A total of 178 female patients (9 [5.1%] Asian, 8 [4.5%] Black or African American, and 123 [69.1] White individuals) were randomized to receive treatment with etirinotecan pegol (92 [51.7%]; median [range] age, 53 [27-79] years) or chemotherapy (86 [48.3%]; median [range] age, 52 [24-77] years). Median OS was similar in both groups (etirinotecan pegol, 7.8 months; chemotherapy, 7.5 months; hazard ratio [HR], 0.90; 95% CI, 0.61-1.33; P = .60). Median progression-free survival for non-central nervous system metastases per blinded independent central review for etirinotecan pegol vs chemotherapy was 2.8 and 1.9 months (HR, 0.72; 95% CI, 0.45-1.16; P = .18) and 3.9 vs 3.3 months, respectively, for central nervous system metastases (HR, 0.59; 95% CI, 0.33-1.05; P = .07). Safety profiles between the groups were largely comparable.

Conclusions and Relevance

The results of the ATTAIN randomized clinical trial found no statistically significant difference in outcomes between treatment with etirinotecan pegol and chemotherapy in patients with BM. However, this study represents one of the largest published trials dedicated to patients with breast cancer and BM and may help to inform further research.

Trial Registration

ClinicalTrials.gov Identifier: NCT02915744.

Incidence of brain metastases in patients with early HER2-positive breast cancer receiving neoadjuvant chemotherapy with trastuzumab and pertuzumab

The addition of pertuzumab (P) to trastuzumab (H) and neoadjuvant chemotherapy (NAC) has decreased the risk of distant recurrence in early stage HER2-positive breast cancer. The incidence of brain metastases (BM) in patients who achieved pathological complete response (pCR) versus those who do not is unknown. In this study, we sought the incidence of BM in patients receiving HP-containing NAC as well as survival outcome. We reviewed the medical records of 526 early stage HER2-positive patients treated with an HP-based regimen at Memorial Sloan Kettering Cancer Center (MSKCC), between September 1, 2013 to November 1, 2019. The primary endpoint was to estimate the cumulative incidence of BM in pCR versus non-pCR patients; secondary endpoints included disease free-survival (DFS) and overall survival (OS). After a median follow-up of 3.2 years, 7 out of 286 patients with pCR had a BM while 5 out of 240 non-pCR patients had a BM. The 3-year DFS was significantly higher in the pCR group compared to non-pCR group (95% vs 91 %, p = 0.03) and the same trend was observed for overall survival. In our cohort, despite the better survival outcomes of patients who achieved pCR, we did not observe appreciable differences in the incidence of BM by pCR/non-pCR status. This finding suggests that the BM incidence could not be associated with pCR. Future trials with new small molecules able to cross the blood brain barrier should use more specific biomarkers rather than pCR for patients' selection.

Abstract P2-13-06: Clinical implication of HER2 status change after neoadjuvant chemotherapy with Trastuzumab and Pertuzumab (HP) in patients with HER2-positive breast cancer

Background: Patients with early HER2-positive breast cancer (BC) and residual disease after HER2-targeted neoadjuvant chemotherapy (NAC) are at high risk of recurrence. It is estimated that 10-30% of HER2-positive breast cancers change HER2 status after trastuzumab alone, but the effects of adding pertuzumab on this phenomenon and clinical outcomes remain unclear. We previously reported a high rate (~50%) of HER2 status change after HP in a small subset of patients. Herein, we present an updated analysis incorporating pathological review of additional cases.Methods: We identified patients with HER2-positive BC who received NAC with pertuzumab and trastuzumab (NAC-HP) followed by surgery at our institution between September 1, 2013 to November 1, 2019. Patients with HER2 status performed either at MSKCC or outside institutions were included. Change in HER2 status on residual disease from baseline was evaluated. We defined HER2 positivity as immunohistochemistry (IHC) IHC3+ or IHC0-2+ FISH amplified (ratio ≥ 2 or ratio &lt; 2 and HER2 copy number ≥ 6 signals/cell). HER2-low was defined as IHC 1+ or 2+, FISH non-amplified. Disease free survival (DFS) and overall survival (OS) were analyzed using the Kaplan-Meier method. Differences between patients with concordant and discordance HER2 status were assessed using the log-rank test.Results: Of 525 patients receiving NAC with HP, 229 (44%) patients had residual disease post NAC-HP. Among these 229 patients, 141 had both pre and post NAC-HP HER2 status available and were included in this analysis. HER2 status on biopsy specimens was determined at MSKCC in 35/141 (25%) and at external institution in 106/141 (75%). The majority of patients (84%) received dose-dense AC-THP; the remainder received TCHP or other HP-based regimens. Most (96%) of patients continued HP after surgery, and 2 patients received T-DM1. Of the 141 patients, 84/141(60%) were found to be HER2 concordant, while 57 (40%) were found to be HER2 discordant. In 13/57 (23%) patients, HER2 expression was lost (IHC 0), while in 44/57 (77%) patients, HER2-low profile was detected (IHC 1+ in 31, and IHC 2+, FISH non-amplified in 13). Further details are reported in the table. Patients with HER2 discordance after NAC-HP had similar survival outcome compared with patients who remained HER2 concordant (5-years DFS: 92.3% versus 88.7%, p=0.49 and 5-yr OS 93.6% versus 88.4%, p=0.70).Conclusions: In a single center cohort, discordant HER2 status after NAC-HP appeared frequently without statistically significant impact on survival outcome, although this finding may be due to the small size and hence low statistical power. Of these, HER2-low profile is the most frequent post treatment HER2 status change. This raises the possibility that patients with change in HER2 status may have heterogenous expression of HER2 at baseline, and HER2-loss or low sub-clones survive as residual disease due to the selection pressure of HP. Alternatively, anti-HER2 therapy may suppress HER2 expression in surviving cells. These findings could inform studies of tailored approaches in the post-neoadjuvant setting based on the biological profile of residual disease.

Pre NAC-HP HER2 statusNPost NAC-HP HER2 statusNDiscordantN=57IHC 3+: 19IHC0: 4IHC1+: 9IHC2+ FISH not ampl: 6IHC 0-2+ FISH ampl: 38IHC0: 9IHC1+: 22IHC2+ FISH not ampl: 7Concordant N= 84IHC 3+: 59IHC 3+: 47IHC 0- 2+ FISH ampl: 12IHC 0-2+ FISH ampl: 25IHC 3+: 4IHC 0- 2+ FISH ampl: 21

Citation Format: Emanuela Ferraro, Anton Safonov, Hanna Y Wen, Edi Brogi, Mithat Gonan, Andrea V. Barrio, Pedram Razavi, Sarat Chandarlapaty, Shanu Modi, Andrew D. Seidman, Larry Norton, Mark E. Robson, Chau T. Dang. Clinical implication of HER2 status change after neoadjuvant chemotherapy with Trastuzumab and Pertuzumab (HP) in patients with HER2-positive 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 P2-13-06.

Abstract P4-08-01: Effectiveness of electroacupuncture versus auricular acupuncture in breast cancer survivors with chronic musculoskeletal pain: The PEACE randomized clinical trial

Introduction: Chronic musculoskeletal pain is common and debilitating among breast cancer survivors. Recently, the Personalized Electroacupuncture (EA) versus Auricular Acupuncture (AA) Comparative Effectiveness (PEACE) trial demonstrated that both acupuncture methods improved pain control better than usual care (UC) in cancer survivors. However, the comparative effectiveness between EA and AA among breast cancer survivors, specifically, for chronic musculoskeletal pain is unknown. Here, we report the results of breast cancer survivors enrolled in the PEACE trial. Methods: PEACE is a three-arm, parallel, single center randomized trial investigating the effectiveness of EA and AA versus UC for chronic musculoskeletal pain in 360 cancer survivors. Patients in both EA and AA received ten weekly treatments. Patients in UC could receive ten EA treatments after week 12. The primary endpoint was the change in mean Brief Pain Inventory (BPI) pain intensity from baseline to week 12; change from baseline to week 24 was a secondary endpoint. We analyzed the subset of trial participants with a primary diagnosis of breast cancer (46%). We conducted constrained linear mixed model analyses, which constrained all arms to have a common pre-randomization baseline mean. Model-based mean estimates at weeks 12 and 24 were compared between arms using model contrasts. Results: Among the 165 breast cancer survivors, mean (SD) age was 60.3 (11.0) years, 35.8% were non-white, and mean time since cancer diagnosis was 5.4 (6.5) years. Patients had been experiencing pain for 5.6 (7.3) years, with baseline mean pain severity of 5.35 (95% CI: 5.04, 5.66). 86.7% had a prior history of surgery, 43.0% chemotherapy, 64.8% radiotherapy, and 50.3% endocrine therapy. The common locations of pain were lower back (24.2%), knee/leg (23.6%), and shoulder/arm/elbow (13.9%). 107 (66.9%) patients were taking pain medication. At week 12, the BPI pain severity score was 2.69 (2.26. 3.13) in EA, 3.60 (3.17, 4.02) in AA, and 5.06 (4.47, 5.65) in UC. The change in mean BPI intensity score from baseline was -2.65 (-3.06, -2.25), -1.75 (-2.15, -1.35), and -0.29 (-0.86, 0.28) in EA, AA, and UC, respectively (Table 1). At week 24, the mean BPI pain severity was 2.84 (95% Confidence Interval [CI]: 2.40, 3.28) in EA and 3.67 (95% CI: 3.23, 4.10) in AA. EA reduced pain severity significantly more than AA at both week 12, (-0.90 [-1.45, -0.36], p =0.001) and week 24 (-0.82, [-1.38, -0.27], p=0.004). Minimal toxicities were reported. Conclusions: While both EA and AA were associated with clinically meaningful and persistent reduction of pain among breast cancer survivors, EA was more effective than AA at reducing pain severity. Breast cancer survivors with chronic musculoskeletal pain may consider EA.

Table 1.Changes in BPI Pain Intensity from BaselineBPI Pain IntensityUCEAAAEA vs AAChange from baselineChange from baselineDifference from UCChange from baselineDifference from UCDifference between EA and AAWeek 12Mean (95% CI)-0.29 (-0.86, 0.28)-2.65* (-3.06, -2.25)-2.37*(-3.05, -1.68)-1.75* (-2.15, -1.35)-1.46* (-2.14, -0.78)-0.90* (-1.45, -0.36)*p≤0.001

Citation Format: Wanqing Iris Zhi, Jun J Mao, Raymond E Baser, Susan Q Li, Vicotria S Blinder, Larry Norton, Andrew D Seidman, Mark E Robson, Ting Bao. Effectiveness of electroacupuncture versus auricular acupuncture in breast cancer survivors with chronic musculoskeletal pain: The PEACE randomized clinical trial [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 P4-08-01.

Real-world treatment patterns and outcomes of abemaciclib for the treatment of HR+, HER2- metastatic breast cancer

OBJECTIVE

This retrospective observational study described baseline characteristics, real-world treatment patterns, and outcomes among patients with metastatic breast cancer treated with abemaciclib in the United States.

METHODS

De-identified electronic health record-derived data were used to describe patients who began abemaciclib treatment on or after 30 June 2016 and ≥4 months before data cutoff (31 December 2018). Real-world response (rwR) and real-world progression assessments were abstracted from clinical documentation. Descriptive statistics were used to calculate the real-world best response. The Kaplan-Meier method estimated real-world time to first response (rwTTFR) and real-world progression-free survival (rwPFS).

RESULTS

The median age of 118 female patients at abemaciclib initiation was 66.5 years (interquartile range, 57.0, 73.0). The breakdown of patients who received abemaciclib in first, second, third, or later lines was 28.8%, 21.2%, 20.3%, and 29.7%, respectively. Patients received abemaciclib as monotherapy (12.7%) or in combination with endocrine therapy: fulvestrant (59.3%); aromatase inhibitor (22.9%); aromatase inhibitor and fulvestrant (5.1%). There were 68 patients (57.6%) with ≥1 rwR assessment: 41.2% with a real-world complete response or real-world partial response. Median rwTTFR was 3.6 months (95% confidence interval, 3.5, 5.2). Twelve-month rwPFS probability was 61.7%.

CONCLUSIONS

This study represents utilization and outcomes associated with abemaciclib approximately 1 year following FDA approval. Treatment patterns demonstrated heterogeneity and, as in clinical trials, patients appeared to benefit from abemaciclib treatment in the real world. More research investigating outcomes associated with abemaciclib treatment is needed, with larger samples and longer follow-up to enable closer evaluation by subgroup, regimen, and line of therapy.

A phase I trial of sorafenib with whole brain radiotherapy (WBRT) in breast cancer patients with brain metastases and a correlative study of FLT-PET brain imaging

PURPOSE

Sorafenib has demonstrated anti-tumor efficacy and radiosensitizing activity preclinically and in breast cancer. We examined sorafenib in combination with whole brain radiotherapy (WBRT) and explored the [18F] 3'deoxy-3'-fluorothymidine (FLT)-PET as a novel brain imaging modality in breast cancer brain metastases.

METHODS

A phase I trial of WBRT + sorafenib was conducted using a 3 + 3 design with safety-expansion cohort. Sorafenib was given daily at the start of WBRT for 21 days. The primary endpoints were to determine a maximum tolerated dose (MTD) and to evaluate safety and toxicity. The secondary endpoint was CNS progression-free survival (CNS-PFS). MacDonald Criteria were used for response assessment with a correlative serial FLT-PET imaging study.

RESULTS

13 pts were evaluable for dose-limiting toxicity (DLT). DLTs were grade 4 increased lipase at 200 mg (n = 1) and grade 3 rash at 400 mg (n = 3). The MTD was 200 mg. The overall response rate was 71%. Median CNS-PFS was 12.8 months (95%CI: 6.7-NR). A total of 15 pts (10 WBRT + sorafenib and 5 WBRT) were enrolled in the FLT-PET study: baseline (n = 15), 7-10 days post WBRT (FU1, n = 14), and an additional 12 week (n = 9). A decline in average SUV_max of ≥ 25% was seen in 9/10 (90%) of WBRT + sorafenib patients and 2/4 (50%) of WBRT only patients.

CONCLUSIONS

Concurrent WBRT and sorafenib appear safe at 200 mg daily dose with clinical activity. CNS response was favorable compared to historical controls. This combination should be considered for further efficacy evaluation. FLT-PET may be useful as an early response imaging tool for brain metastases.

TRIAL AND CLINICAL REGISTRY

Trial registration numbers and dates: NCT01724606 (November 12, 2012) and NCT01621906 (June 18, 2012).

Clinical trial of proton craniospinal irradiation for leptomeningeal metastases

BACKGROUND

Leptomeningeal metastases (LM) are associated with limited survival and treatment options. While involved-field radiotherapy is effective for local palliation, it lacks durability. We evaluated the toxicities of proton craniospinal irradiation (CSI), a treatment encompassing the entire central nervous system (CNS) compartment, for patients with LM from solid tumors.

METHODS

We enrolled patients with LM to receive hypofractionated proton CSI in this phase I prospective trial. The primary endpoint was to describe treatment-related toxicity, with dose-limiting toxicity (DLT) defined as any radiation-related grade 3 non-hematologic toxicity or grade 4 hematologic toxicity according to the Common Terminology Criteria for Adverse Events that occurred during or within 4 weeks of completion of proton CSI. Secondary endpoints included CNS progression-free survival (PFS) and overall survival (OS).

RESULTS

We enrolled 24 patients between June 2018 and April 2019. Their median follow-up was 11 months. Twenty patients were evaluable for protocol treatment-related toxicities and 21 for CNS PFS and OS. Two patients in the dose expansion cohort experienced DLTs consisted of grade 4 lymphopenia, grade 4 thrombocytopenia, and/or grade 3 fatigue. All DLTs resolved without medical intervention. The median CNS PFS was 7 months (95% CI: 5-13) and the median OS was 8 months (95% CI: 6 to not reached). Four patients (19%) were progression-free in the CNS for more than 12 months.

CONCLUSION

Hypofractionated proton CSI using proton therapy is a safe treatment for patients with LM from solid tumors. We saw durable disease control in some patients.

The Evolution of Clinical Trials in Metastatic Breast Cancer: Design Features and Endpoints That Matter

The evolution of thought in assessing benefit in clinical trials of systemic therapy for metastatic breast cancer (MBC) is well documented, with most agents garnering regulatory approval based either on an advantage in overall survival (OS), time to progression (TTP), or progression-free survival (PFS) over an existing standard of care or objective response rate (ORR). Previous guidance for industry on clinical trial endpoints for the approval of cancer drugs and biologics was provided by the U.S. Food and Drug Administration (FDA) in 2007 and recently updated in 2018. The more recent FDA guidance recognizes that advances in science are facilitating the development of oncology products, which "may also result in the identification of additional endpoints that may be used to support approval of oncology products." This article critically addressed the evolution of thought on the advancement of clinical trials in MBC, from various stakeholder perspectives. Despite the term "stakeholder," the objective of all co-authors and parties concerned is to promote and inform the optimal design, conduct, and reporting of clinical trials for women with advanced breast cancer toward improving and extending lives. This article provides an overview of the evolving perspectives on this issue from the physician, regulatory agency, and patient and/or advocate points of view.

Phase I Study of Intermittent High-Dose Lapatinib Alternating with Capecitabine for HER2-Positive Breast Cancer Patients with Central Nervous System Metastases

PURPOSE

Lapatinib and capecitabine cross the blood-tumor barrier in breast cancer brain metastasis but have modest clinical efficacy. Administration of high-dose tyrosine kinase inhibitor has been evaluated in brain metastases and primary brain tumors as a strategy to improve drug exposure in the central nervous system (CNS). We derived a rational drug scheduling of intermittent high-dose lapatinib alternating with capecitabine based on our preclinical data and Norton-Simon mathematical modeling. We tested this intermittent, sequential drug schedule in patients with breast cancer with CNS metastasis.

PATIENTS AND METHODS

We conducted a phase I trial using an accelerated dose escalation design in patients with HER2-positive (HER2+) breast cancer with CNS metastasis. Lapatinib was given on day 1-3 and day 15-17 with capecitabine on day 8-14 and day 22-28 on an every 28-day cycle. Lapatinib dose was escalated, and capecitabine given as a flat dose at 1,500 mg BID. Toxicity and efficacy were evaluated.

RESULTS

Eleven patients were enrolled: brain only (4 patients, 36%), leptomeningeal (5 patients, 45%), and intramedullary spinal cord (2 patients, 18%). Grade 3 nausea and vomiting were dose-limiting toxicities. The MTD of lapatinib was 1,500 mg BID. Three patients remained on therapy for greater than 6 months.

CONCLUSIONS

High-dose lapatinib is tolerable when given intermittently and sequentially with capecitabine. Antitumor activity was noted in both CNS and non-CNS sites of disease. This novel administration regimen is feasible and efficacious in patients with HER2+ breast cancer with CNS metastasis and warrants further investigation.

ATTAIN: Phase III study of etirinotecan pegol versus treatment of physician's choice in patients with metastatic breast cancer and brain metastases

The increasing incidence of breast cancer brain metastases is a major clinical problem with its associated poor prognosis and limited treatment options. The long-acting topoisomerase-1 inhibitor, etirinotecan pegol, was designed to preferentially accumulate in tumor tissue including brain metastases, providing sustained cytotoxic SN38 levels. Motivated by improved survival findings from subgroup analyses from the Phase III BEACON trial, this ongoing randomized, Phase III trial compares etirinotecan pegol to drugs commonly used for advanced breast cancer in patients with stable, treated breast cancer brain metastases who have been previously treated with an anthracycline, taxane and capecitabine. The primary end point is overall survival. Secondary end points include objective response rate, progression-free survival and time to CNS disease progression or recurrence in patients with/without CNS lesions present at study entry. Trial registration number: NCT02915744.

Abstract P1-19-03: A phase I trial of sorafenib with whole brain radiotherapy (WBRT) in breast cancer patients with brain metastases and a correlative study of FLT-PET brain imaging in patients receiving WBRT with or without sorafenib

Background: WBRT is a standard therapy for metastatic breast cancer (MBC) patients (pts) with brain metastases (BM), but disease progression in the brain is common. Sorafenib, a tyrosine kinase inhibitor with anti-VEGF activity, has demonstrated anti-tumor efficacy in MBC and radiosensitizing activity preclinically. [18F] 3'deoxy-3'-fluorothymidine (FLT) is a new PET tracer which correlates with cellular proliferation and may improve response assessment in the brain. Methods: A phase I trial of sorafenib with WBRT in MBC pts with BM was conducted using a 3+3 design. Sorafenib was given orally daily at the start of WBRT for a total of 21 days with 3 doses levels: 200mg, 400mg, and 600mg. The primary endpoints were to determine a maximum tolerated dose (MTD) and to evaluate safety and toxicity. The secondary endpoint was central nervous system progression-free survival (CNS-PFS). Macdonald Criteria were used for response assessment with serial MRI brain imaging. Key eligibility criteria include MBC with new or progressive ≥ 1cm BM, ECOG PS 0-2, non-escalating corticosteroid dose, and no other concurrent anti-tumor therapy except trastuzumab. In parallel, we conducted a correlative FLT-PET imaging study (baseline, 7-10 days (FU1), and 10-12 weeks (FU2) after the WBRT) to assess radiographic changes among pts receiving WBRT + sorafenib and in a separate WBRT only cohort. FLT standard uptake value (SUV) and kinetic parameter data were obtained. Results: 13 pts were treated in the dose escalation phase and evaluable for dose-limiting toxicity (DLT). The median age was 56 years (range: 43-77). There were 4 HER2 positive (31%) and 3 triple negative (23%) pts. 2 pts had prior stereotactic radiosurgery. DLTs were: Grade (G) 4 increased lipase at 200mg (1 pt) and G3 rash at 400mg (3 pts) level. MTD was determined to be 200mg. 10 pts were evaluable for response (at least 1 follow up brain imaging). The overall response rate was 70%: 4 complete responses (CR) + 3 partial responses. All 13 pts were evaluated for CNS PFS with a median follow up of 29.7 months (min 19.6, max 57.4mo). Median CNS-PFS was 8.2 months (95%CI: 3.4-31.8). Median OS was 15.4 months (95% CI: 3.4-NR). A total of 10 pts with WBRT and sorafenib and 5 pts with WBRT only were enrolled in the FLT-PET study: all 15 pts had baseline FLT PET, 14 with FU1, and 9 with FU2. 55 baseline lesions, 38 at FU1 and 15 at FU2 were observed and analyzed. All lesions with FLT uptake had MRI correlates. Decline in average SUVmax of ≥25% was seen in 9/10 (90%) of WBRT+sorafenib and 2/4(50%) of WBRT only pts at FU1. A complete disappearance of FLT uptake was noted in 1 pt at FU1 and 2 more pts at FU2. Conclusions: Concurrent WBRT with sorafenib appears safe at 200mg daily dose with a higher rate of CR compared to historical WBRT data. We are currently enrolling patients in the safety-expansion cohort. This combination should be considered for further efficacy evaluation. Additional analysis of FLT-PET as a complementary imaging modality to MRI is currently ongoing. Clinical trial registry: NCT01724606 and NCT01621906. Support: Bayer, Susan G Komen, ASCO Gianni Bonadonna Breast Cancer Award

Citation Format: Morikawa A, Jhaveri K, Grkovski M, Tang K, Humm JL, Holodny A, Beal K, Schoder H, Seidman AD. A phase I trial of sorafenib with whole brain radiotherapy (WBRT) in breast cancer patients with brain metastases and a correlative study of FLT-PET brain imaging in patients receiving WBRT with or without sorafenib [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 P1-19-03.

Summary of head-to-head comparisons of patient risk classifications by the 21-gene Recurrence Score® (RS) assay and other genomic assays for early breast cancer

Many genomic assays that assess recurrence risk in early breast cancer (EBC) are prognostic, but they differ in risk group stratification, which can affect clinical utility. Prospective outcomes of >60 K patients treated based on the 21-gene assay results have shown that chemotherapy may be safely omitted in EBC patents with low Recurrence Score (RS) results (RS < 18). Because of its extensive validation and wide clinical use, the RS assay is a common comparator in head-to-head studies with other assays. Published/presented studies of the RS assay performed on the same tumor samples with Breast Cancer Index (BCI), EndoPredict (EP) or EP+ clinical features (EPclin), MammaPrint (MMP) and/or Prosigna (ROR) assays were reviewed. Study findings were summarized descriptively.

"A Tool, Not a Crutch": Patient Perspectives About IBM Watson for Oncology Trained by Memorial Sloan Kettering

PURPOSE

IBM Watson for Oncology trained by Memorial Sloan Kettering (WFO) is a clinical decision support tool designed to assist physicians in choosing therapies for patients with cancer. Although substantial technical and clinical expertise has guided the development of WFO, patients' perspectives of this technology have not been examined. To facilitate the optimal delivery and implementation of this tool, we solicited patients' perceptions and preferences about WFO.

METHODS

We conducted nine focus groups with 46 patients with breast, lung, or colorectal cancer with various treatment experiences: neoadjuvant/adjuvant chemotherapy, chemotherapy for metastatic disease, or systemic therapy through a clinical trial. In-depth qualitative and quantitative data were collected and analyzed to describe patients' attitudes and perspectives concerning WFO and how it may be used in clinical care.

RESULTS

Analysis of the qualitative data identified three main themes: patient acceptance of WFO, physician competence and the physician-patient relationship, and practical and logistic aspects of WFO. Overall, participant feedback suggested high levels of patient interest, perceived value, and acceptance of WFO, as long as it was used as a supplementary tool to inform their physicians' decision making. Participants also described important concerns, including the need for strict processes to guarantee the integrity and completeness of the data presented and the possibility of physician overreliance on WFO.

CONCLUSION

Participants generally reacted favorably to the prospect of WFO being integrated into the cancer treatment decision-making process, but with caveats regarding the comprehensiveness and accuracy of the data powering the system and the potential for giving WFO excessive emphasis in the decision-making process. Addressing patients' perspectives will be critical to ensuring the smooth integration of WFO into cancer care.

Phase 2 Study of Dose-Dense Doxorubicin and Cyclophosphamide Followed by Eribulin Mesylate With or Without Prophylactic Growth Factor for Adjuvant Treatment of Early-Stage Human Epidermal Growth Factor Receptor 2-Negative Breast Cancer

BACKGROUND

Eribulin has significantly improved overall survival for patients with metastatic breast cancer who received ≥ 2 prior chemotherapy regimens for advanced disease. This trial assessed eribulin as adjuvant therapy for patients with early-stage breast cancer.

PATIENTS AND METHODS

Patients with human epidermal growth factor receptor 2-negative, stage I to III breast cancer received doxorubicin 60 mg/m2 and cyclophosphamide 600 mg/m2 provided intravenously on day 1 of each 14-day cycle for 4 cycles, with pegfilgrastim on day 2, followed by 4 cycles of eribulin mesylate 1.4 mg/m2 provided intravenously on days 1 and 8 every 21 days. There were 2 cohorts, as follows: cohort 1: no prophylactic growth factor with eribulin (allowed at physician's discretion only); cohort 2: prophylactic filgrastim with eribulin. The primary end point was feasibility, defined as the percentage of patients who completed the eribulin portion of the regimen without a dose omission, delay, or reduction due to an eribulin-related adverse event. Relative dose intensity of eribulin and toxicities are summarized by cohort. Exploratory end points included 3-year disease-free survival and overall survival.

RESULTS

Eighty-one patients (cohort 1, n = 55; cohort 2, n = 26) entered the treatment phase; 88% completed treatment. Feasibility was 72.9 % (90% confidence interval, 60.4, 83.2) in cohort 1 and 60.0% (90% confidence interval, 41.7, 76.4) in cohort 2. The most frequent eribulin-related adverse events (all grades) were fatigue (75.9%), peripheral neuropathy (54.4%), nausea (39.2%), neutropenia (35.4% [31.5% of patients in cohort 1; 44.0% in cohort 2]), and arthralgia (26.6%).

CONCLUSION

The primary end point of > 80% feasibility was not met. No unexpected adverse events were observed, and 62% of patients received full dosing with no dose delay or reduction. Further investigation of this regimen with alternative dosing schedules or use of growth factors could be considered.

National Cancer Institute Breast Cancer Steering Committee Working Group Report on Meaningful and Appropriate End Points for Clinical Trials in Metastatic Breast Cancer

PURPOSE

To provide evidence-based consensus recommendations on choice of end points for clinical trials in metastatic breast cancer, with a focus on biologic subtype and line of therapy.

METHODS

The National Cancer Institute Breast Cancer Steering Committee convened a working group of breast medical oncologists, patient advocates, biostatisticians, and liaisons from the Food and Drug Administration to conduct a detailed curated systematic review of the literature, including original reports, reviews, and meta-analyses, to determine the current landscape of therapeutic options, recent clinical trial data, and natural history of four biologic subtypes of breast cancer. Ongoing clinical trials for metastatic breast cancer in each subtype also were reviewed from ClinicalTrials.gov for planned primary end points. External input was obtained from the pharmaceutic/biotechnology industry, real-world clinical data specialists, experts in quality of life and patient-reported outcomes, and combined metrics for assessing magnitude of clinical benefit.

RESULTS

The literature search yielded 146 publications to inform the recommendations from the working group.

CONCLUSION

Recommendations for appropriate end points for metastatic breast cancer clinical trials focus on biologic subtype and line of therapy and the magnitude of absolute and relative gains that would represent meaningful clinical benefit.

Phase II Study of Paclitaxel and Dasatinib in Metastatic Breast Cancer

BACKGROUND

Overexpression and activation of tyrosine kinase Src has been linked to breast carcinogenesis and bone metastases. We showed the feasibility of combining the SRC inhibitor dasatinib with weekly paclitaxel in patients with metastatic breast cancer (MBC) and herein report the subsequent phase II trial.

PATIENTS AND METHODS

Patients had received ≤ 2 chemotherapy regimens for measurable, HER2-negative MBC. Patients received paclitaxel and dasatinib (120 mg daily) and were assessed according to Response Evaluation Criteria in Solid Tumors for overall response rate (ORR), the primary end point. Secondary end points included progression-free survival (PFS) and overall survival (OS). A 30% ORR (n = 55) was deemed worthy of further investigation. Exploratory biomarkers included N-telopeptide (NTX) and plasma vascular epidermal growth factor (VEGF) receptor 2 as predictors of clinical benefit.

RESULTS

From March 2010 to March 2014, 40 patients, including 2 men enrolled. The study was stopped early because of slow accrual. Overall, 32 patients (80%) had estrogen receptor-positive tumors and 23 (58%) had previously received taxanes. Of the 35 assessable patients, 1 (3%) had complete response and 7 (20%) partial response, resulting in an ORR of 23%. The median PFS and OS was 5.2 (95% confidence interval [CI], 2.9-9.9) and 20.6 (95% CI, 12.9-25.2) months, respectively. As expected, fatigue (75%), neuropathy (65%), and diarrhea (50%) were common side effects, but were generally low-grade. Median baseline NTX was similar in patients who had clinical benefit (8.2 nmol BCE) and no clinical benefit (10.9 nmol BCE). Similarly, median baseline VEGF levels were similar between the 2 groups; 93.0 pg/mL versus 83.0 pg/mL.

CONCLUSION

This phase II study of dasatinib and paclitaxel was stopped early because of slow accrual but showed some clinical activity. Further study is not planned.

Abstract OT2-07-10: ATTAIN: Phase 3 study of etirinotecan pegol (EP) vs treatment of physician's choice (TPC) in patients (pts) with metastatic breast cancer (MBC) who have stable brain metastases (BM) previously treated with an anthracycline, a taxane, and capecitabine (ATC)

Background: EP is a next generation topoisomerase I inhibitor-polymer conjugate that provides continuous exposure to SN-38, the active metabolite. A BM mouse model showed high penetration and retention of SN-38 in CNS lesions, resulting in decreased size of CNS lesions and improved survival (OS) at concentrations achieved at the recommended dose in pts (Adkins BMC Cancer 2015). A Phase 3 trial (BEACON) of EP vs TPC in 852 pts with advanced BC did not meet its primary endpoint of OS (HR 0.087 p=0.08); a subset of 67 pts with stable BM showed improved OS (HR 0.51 [95% CI 0.30-0.86] p&lt;0.01) (Perez Lancet Oncol 2015). The current Phase 3 trial (ATTAIN) was designed for this subpopulation of pts having high unmet medical need.

Methods: Pts with MBC with locally treated stable BM will be randomized 1:1 to EP vs TPC in an open-label, randomized Phase 3 study. Eligibility includes ECOG PS 0 or 1; adequate organ function who received prior ATC (in neo/adjuvant or locally advanced/MBC setting) pts must have had ≥1 prior cytotoxic regimen for MBC (triple negative BC) ≥2 prior cytotoxic regimens and either 1 prior hormone therapy (HR+ BC) or 1 prior HER2 targeted therapy (HER2+ BC). Pts must have undergone definitive local therapy of BM (whole brain radiation [RT] stereotactic RT or surgical resection as single-agent or combination) signs/symptoms of BM must be stable with steroids unchanged or decreasing for ≥ 7 days prior to randomization. Primary endpoint is OS. Key secondary endpoints: ORR and PFS by RECIST v1.1 and RANO-BM, clinical benefit rate (ORR+SD ≥ 6 months) and QoL. Pts randomized to TPC will receive 1 of 7 IV cytotoxic agents. Pts are stratified by region, PS and receptor status. 350 pts will be randomized to obtain number of events required at 90% power to detect a statistically significant improvement in OS (hypothesizing HR=0.67) 1 interim analysis at 50% of deaths (130 events) will be performed. PK sampling and UGT1A1 testing will be performed in the EP arm; plasma ctDNA will be assessed for potential predictive markers of efficacy. Enrollment began early 2017. For enrollment information contact Dr. Alison Hannah, Dr. Mary Tagliaferri, or Minnie Kuo at StudyInquiry@nektar.com. NCT02915744

Citation Format: Tripathy D, Sara T, Seidman AD, Anders CK, Ibrahim N, Rugo HS, Twelves CJ, Diéras V, Müller V, Hannah A, Tagliaferri M, Cortés J. ATTAIN: Phase 3 study of etirinotecan pegol (EP) vs treatment of physician's choice (TPC) in patients (pts) with metastatic breast cancer (MBC) who have stable brain metastases (BM) previously treated with an anthracycline, a taxane, and capecitabine (ATC) [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 OT2-07-10.

Characteristics and Prognostic Factors for Patients With HER2-overexpressing Breast Cancer and Brain Metastases in the Era of HER2-targeted Therapy: An Argument for Earlier Detection

BACKGROUND

Although brain metastases (BM) are associated with poor prognosis, patients with human epidermal growth factor receptor 2 (HER2) overexpressing (HER2⁺) breast cancer (BC) with BM who are treated with anti-HER2 therapy have a relatively longer survival after BM diagnosis compared with other subtypes and HER2⁺ patients previously untreated with anti-HER2 therapy. It is unclear if previously reported prognostic factors are applicable to patients with HER2⁺ BC in the era of HER2-targeted therapy.

PATIENTS AND METHODS

We evaluated 100 consecutive patients with HER2⁺ BC with BM who underwent radiation therapy as primary BM treatment from January 2001 to December 2011 at Memorial Sloan Kettering Cancer Center by retrospective review. Patient characteristics at the time of BM diagnosis and their associations with time from BM to death were evaluated by Kaplan-Meier curves, log-rank tests, and Cox proportional hazard models.

RESULTS

Significantly better survival from BM was noted for patients with higher performance status, fewer BM lesions, continued use of HER2-targeted therapy after BM diagnosis, and better controlled extracranial metastatic disease. Absence of neurologic symptoms at BM diagnosis was significantly associated with fewer lesions, decreased use of whole brain radiotherapy, and longer survival in univariate and multivariate analysis (multivariate hazard ratio, 3.69; 95% confidence interval, 1.69-8.07).

CONCLUSION

Our finding supports the continued use of HER2-targeted therapy after BM diagnosis. In addition, future research on the clinical impact of detecting asymptomatic BM in patients with HER2⁺ BC, in terms of improving prognosis, quality of life, and avoidance of whole brain radiotherapy, is warranted.

Long-term chemotherapy-induced peripheral neuropathy among breast cancer survivors: prevalence, risk factors, and fall risk

Chemotherapy-induced peripheral neuropathy (CIPN) is a common toxicity associated with chemotherapy, but researchers rarely study its risk factors, fall risk, and prevalence in long-term breast cancer survivors. We aimed to determine CIPN prevalence, risk factors, and association with psychological distress and falls among long-term breast cancer survivors. We conducted Cross-sectional analyses among postmenopausal women with a history of stage I-III breast cancer who received taxane-based chemotherapy. Participants reported neuropathic symptoms of tingling/numbness in hands and/or feet on a 0-10 numerical rating scale. We conducted multivariate logistic regression analyses to evaluate risk factors associated with the presence of CIPN and the relationship between CIPN and anxiety, depression, insomnia, and patient-reported falls. Among 296 participants, 173 (58.4 %) reported CIPN symptoms, 91 (30.7 %) rated their symptoms as mild, and 82 (27.7 %) rated them moderate to severe. Compared with women of normal weight, being obese was associated with increased risk of CIPN (adjusted OR 1.94, 95 % CI: 1.03-3.65). Patients with CIPN reported greater insomnia severity, anxiety, and depression than those without (all p < 0.05). Severity of CIPN was associated with higher rates of falls, with 23.8, 31.9, and 41.5 % in the "no CIPN," "mild," and "moderate-to-severe" groups, respectively, experiencing falls (p = 0.028). The majority of long-term breast cancer survivors who received taxane-based chemotherapy reported CIPN symptoms; obesity was a significant risk factor. Those with CIPN also reported increased psychological distress and falls. Interventions need to target CIPN and comorbid psychological symptoms, and incorporate fall prevention strategies for aging breast cancer survivors.

Characteristics and Outcomes of Patients With Breast Cancer With Leptomeningeal Metastasis

BACKGROUND

Disease presentation, prognostic factors, and treatment patterns for patients with breast cancer with leptomeningeal metastasis are not well characterized. In this study, we examined patient characteristics and prognostic factors for survival after a diagnosis of leptomeningeal metastasis.

PATIENTS AND METHODS

Three hundred eighteen consecutive patients with breast cancer diagnosed with leptomeningeal metastasis from January 1998 to December 2013 at Memorial Sloan Kettering Cancer Center were identified. Clinicopathologic and treatment information were obtained in a retrospective review. Associations with time from leptomeningeal diagnosis to death were evaluated according to Kaplan-Meier curves, log rank tests, and Cox proportional hazard models.

RESULTS

Of the 318 patients, 44% were hormone receptor-positive (HR+) HER2^-, 18% were HR⁺HER2⁺, 8.5% were HR^-HER2⁺, 25.5% were triple-negative; and 4% had missing information. The median survival was 3.5 months (95% confidence interval, 3.0-4.0) with 63 patients (20%) surviving >1 year. Recent diagnosis (after 2006), HER2⁺ subtype, higher performance status, cranial-only involvement, and no evidence of noncentral nervous system disease were independently associated with improved survival in multivariate analysis.

CONCLUSION

Despite the improvement noted with the more recent years of diagnosis, survival after a diagnosis of leptomeningeal metastasis remains poor. Similar to patients with parenchymal brain metastasis only, the survival differs among different receptor subtypes. A closer examination to identify factors, such as introduction of new systemic therapies that might contribute to longer-term survival might provide insight to improve management of these patients. In addition, factors we identified that are associated with survival might be considered as stratification variables in the design of future randomized clinical trials in this population.

Abstract P4-14-24: Optimization of intermittent high dose lapatinib administration with or without capecitabine: A rational approach to drug dosing and scheduling using Norton-Simon modeling

Background: Systemic treatment of central nervous system (CNS) metastases remains a challenge partially due to poor drug penetration. Lapatinib and capecitabine are drugs with modest efficacy in treatment of brain metastases from HER2-positive (+) breast cancer (BC) and were shown to cross the blood-tumor barrier in clinical craniotomy specimens (Lin N et al., CCR 2009, Morikawa A et al., Neuro Oncol 2015). However, intratumoral drug concentrations observed were sub-optimal and heterogeneous. Administration of shorter-duration, high dose tyrosine kinase inhibitor is proposed as a way to improve efficacy and tolerability based on Norton-Simon modeling and drug exposure in the CNS (Traina T et al., JCO 2008, Grommes C et al., Neuro Oncol 2011, Chien AJ et al., J Clin Oncol 2014) . In this study, we examined optimization of high dose lapatinib administration with or without capecitabine to inform the design of a phase I trial for BC patients with HER2+ CNS metastases.

Methods: Mice bearing BT-474 BC xenograft tumors were treated with various lapatinib doses and schedules. A standard continuous daily dose (100mg/kg) was compared to various intermittent dosing schedules (at 100mg/kg, 400mg/kg, and 800mg/kg). In addition, high dose lapatinib (800mg/kg) was administered with capecitabine either concurrently or in tandem. Xenografts were treated when tumors reached 100mm3. Tumor volumes were evaluated for antitumor efficacy, and mice weights were measured for toxicity. Significance testing for between-group comparisons was conducted using a mixed effect model for repeated measures.

Results: Intermittent schedules of lapatinib at 100mg/kg given as 3 days on/11 days off (3/11), 5 days on/9 days off (5/9), and 7 days on/7days off (7/7) had a similar efficacy in tumor control: percent change in tumor volume of 225% (7/7), 222% (5/9), and 223% (3/11) (NS). Therefore, the 3 days on (with 4 days off or 11 days off ) schedule was subsequently chosen to evaluate for tolerability and antitumor efficacy of higher lapatinib dose. The 3 days on/4 days off (3/4) group at 800mg/kg demonstrated the highest tumor reduction (-69%) compared to the daily continuous dosing group (-18%) (p=0.04), but a trend toward higher toxicity was observed (p=0.12). Evaluation of concurrent vs. tandem administration of capecitabine with lapatinib at 800mg/kg given in 3 days on/11 days off was conducted. The concurrent treatment was discontinued early due to high toxicity. However, tandem administration of capecitabine with high dose lapatinib was tolerable without a significant difference in weight changes (p=0.62).

Conclusions: The intermittent schedule allows delivery of high dose lapatinib, which has better anti-tumor activity than standard continuous dosing. If given intermittently, high dose lapatinib is tolerable, even with capecitabine if given in tandem/sequence. Based on the result of these experiments, a phase I trial of high dose lapatinib using 3 days on/11 days off schedule in tandem with capecitabine is currently proposed for treatment of HER2-positive BC patient with CNS metastases.

Citation Format: Morikawa A, De Stanchina E, Patil S, Chandarlapaty S, Li BT, Norton L, Seidman AD. Optimization of intermittent high dose lapatinib administration with or without capecitabine: A rational approach to drug dosing and scheduling using Norton-Simon modeling. [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 P4-14-24.

Abstract P1-12-05: Phase 2 study of dose-dense doxorubicin and cyclophosphamide followed by eribulin mesylate with or without prophylactic growth factor for adjuvant treatment of early-stage breast cancer

Background: Eribulin has demonstrated antitumor activity and significantly improved overall survival (OS) in patients (pts) with heavily pretreated locally advanced/metastatic breast cancer (BC). This trial assessed the feasibility of eribulin as adjuvant therapy following dose-dense doxorubicin and cyclophosphamide (AC) for pts with human epidermal growth factor receptor 2 (HER2)-negative early-stage BC.

Methods: Pts with HER2(-), stage I–III, invasive BC were enrolled. Pts received dose-dense AC (doxorubicin 60 mg/m2 IV and cyclophosphamide 600 mg/m2 IV) on D1 of each 14-day cycle for 4 cycles with pegfilgrastim, followed by 4 cycles of eribulin (1.4 mg/m2 IV) on D1 and D8 every 21 days. Pts were divided into 2 cohorts: Cohort 1 did not receive any prophylactic growth factor (GF); Cohort 2 received a short course of prophylactic GF (filgrastim) on days 3, 4, 10, and 11 of each eribulin cycle. Primary endpoint of feasibility was determined as %pts who completed eribulin portion of the regimen without a dose delay (&gt;2 days) or reduction due to eribulin-related adverse event (AE). Based on similar previous studies, the target for feasibility was 80%. Relative dose intensity of eribulin and toxicities were also summarized by cohort. Exploratory objectives include efficacy endpoints of 3-yr disease-free survival and OS.

Results: We report data from 81 pts (55 Cohort 1; 26 Cohort 2) enrolled in the study, of whom 88% completed study treatment. Pt characteristics include median age 49 yrs (range 26–69), ECOG status 0 (85%), BC stages 1/2/3 (21%/57%/22%). Of 90% (73/81) pts evaluable for feasibility, 27% and 40% of pts in Cohorts 1 and 2, respectively, had dose delay or reduction during eribulin treatment, indicating the primary endpoint was not met. Overall, results were similar between the 2 cohorts (Table). Median duration of treatment with eribulin was 10.14 weeks in both cohorts (vs 10 weeks planned). Most eribulin-related dose delays were due to grade 3 (n=18) or grade 4 (n=7) neutropenia. Non-fatal serious AEs were observed in 11% of pts in Cohort 1 and 15% in Cohort 2. Discontinuations due to AEs occurred in 6% of pts in Cohort 1 and 0 in Cohort 2. Neutropenia (all grades) was reported in 36% of pts in Cohort 1 and 42% in Cohort 2. Most common AEs (all grades) were fatigue (96%), nausea (75%), alopecia (73%), hot flush (63%), and constipation (57%).

 ACEribulin Cohort 1*Cohort 2*Cohort 1 (without GCSF)Cohort 2 (with GCSF)Relative dose intensity, mean99.5%99.0%92.0%90.9%Completed all planned doses98.2%96.2%87.0%84.0%Dose modification†12.7%15.4%35.2%40.0%GCSF, granulocyte-colony simulating factor. *With pegfilgrastim 6 mg given subcutaneously on D2 of each AC cyle; † including dose delays (&gt;2 days)/reduction/interruptions, missing, and permanent discontinuation due to AE.

Conclusions: The primary study endpoint of &gt;80% feasibility of planned dose delivery without any dose delays or reduction was not met. However, adjuvant treatment with dose-dense AC-eribulin was given safely, with two-thirds (67%) of pts achieving full dosing with no dose delay or reduction. Investigation into alternative dosing schedules or GF support is recommended.

Citation Format: Cadoo K, Kaufman PA, Hudis C, Chang C, Berrak E, Song J, Seidman AD, Traina TA. Phase 2 study of dose-dense doxorubicin and cyclophosphamide followed by eribulin mesylate with or without prophylactic growth factor for adjuvant treatment of early-stage breast cancer. [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 P1-12-05.

Capecitabine and lapatinib uptake in surgically resected brain metastases from metastatic breast cancer patients: a prospective study

BACKGROUND

Breast cancer brain metastases (BCBM) are challenging complications that respond poorly to systemic therapy. The role of the blood-tumor barrier in limiting BCBM drug delivery and efficacy has been debated. Herein, we determined tissue and serum levels of capecitabine, its prodrug metabolites, and lapatinib in women with BCBM resected via medically indicated craniotomy.

METHODS

Study patients with BCBM requiring surgical resection received either single-dose capecitabine (1250 mg/m(2)) 2-3 h before surgery or 2-5 doses of lapatinib (1250 mg) daily, the last dose 2-3 h before surgery. Serum samples were collected serially on the day of surgery. Drug concentrations were determined in serum and BCBM using liquid chromatography tandem mass spectrometry.

RESULTS

Twelve patients were enrolled: 8 for capecitabine and 4 for lapatinib. Measurable drug levels of capecitabine and metabolites, 5'-deoxy-5-fluorocytidine, 5'-deoxy-5-fluorouridine, and 5-fluorouracil, were detected in all BCBM. The ratio of BCBM to serum was higher for 5-fluorouracil than for capecitabine. As for lapatinib, the median BCBM concentrations ranged from 1.0 to 6.5 µM. A high variability (0.19-9.8) was noted for lapatinib BCBM-to-serum ratio.

CONCLUSIONS

This is the first study to demonstrate that capecitabine and lapatinib penetrate to a significant though variable degree in human BCBM. Drug delivery to BCBM is variable and in many cases appears partially limiting. Elucidating mechanisms that limit drug concentration and innovative approaches to overcome limited drug uptake will be important to improve clinical efficacy of these agents in the central nervous system. Trial registration ID: NCT00795678.

A pooled analysis of gemcitabine plus docetaxel versus capecitabine plus docetaxel in metastatic breast cancer

In two randomized phase III trials of patients with metastatic breast cancer (MBC), gemcitabine-docetaxel (GD) and capecitabine-docetaxel (CD) had similar efficacy, but distinct safety profiles. Methods. Data from two GD versus CD studies were pooled; overall survival (OS), progression-free survival (PFS), and overall response rate (ORR) were determined. Cox proportional hazards models identified prognostic factors associated with improved OS and PFS. Using a multivariate prognostic model incorporating identified adverse prognostic factors, we grouped MBC patients into low-, intermediate-, and high-risk categories. Hazard ratios (HRs) of GD over CD for OS and PFS were determined for subsets of patients. Results. Baseline demographics of the pooled population were mostly well balanced. In the pooled population, there were no significant differences between GD versus CD for OS (HR = 1.02; p = .824), PFS (HR = 1.15; p = .079), and ORR (p = .526). In the pooled crossover population, there were trends toward improved OS (HR = 0.82; p = .171) and PFS (HR = 0.93; p = .557) with GD. Several prognostic factors (including prior adjuvant taxane) for improved OS or PFS were identified; however, there were no significant interactions between treatment arms and prognostic factors for PFS or OS, except number of metastatic sites. In the prognostic model, median OS and PFS were numerically lower in the high-risk group versus the intermediate- and low-risk groups. Conclusion. This analysis confirms the lack of efficacy difference between GD and CD in the pooled population, crossover population, and almost all subpopulations. Several prognostic factors were associated with improved outcomes in the pooled population.

Phase II trial of patupilone in patients with brain metastases from breast cancer

BACKGROUND

For patients with progressive breast cancer brain metastasis (BCBM) after whole brain radiotherapy (WBRT), few options exist. Patupilone is an epothilone that crosses the blood-brain barrier. We hypothesized that patupilone would produce a 35% 3-month CNS progression-free survival in women with BCBM after WBRT.

METHODS

This multicenter phase II trial included 2 cohorts. Group A included women with progressive BCBM after WBRT. Group B was an exploratory cohort of patients with either leptomeningeal metastases or untreated brain metastases. The primary goal was to observe a 35% 3-month CNS progression-free survival in Group A. The sample size was 45 for Group A and 10 for Group B. Patients received patupilone 10 mg/m(2) once every 3 weeks until progression. Responses were scored according to the Macdonald criteria.

RESULTS

Fifty-five patients (45 in Group A, 10 in Group B) enrolled. In Group A, the 3-month CNS progression-free survival was 27%, the median overall survival was 12.7 months, and the overall response rate was 9%. In Group B, which enrolled 5 patients with leptomeningeal disease and 5 with no prior WBRT, no responses occurred and 8 patients had CNS progression before 3 months. Systemic responses occurred in 15% of patients, including a complete response in liver metastases. Diarrhea occurred in 87% of patients; 25% had grade 3 and 4 adverse events.

CONCLUSIONS

Patupilone in patients with BCBM did not meet the efficacy criteria and had significant gastrointestinal toxicity. Further study of brain-penetrant agents is warranted for patients with CNS metastases from breast cancer.

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.

Abstract P6-11-02: Patient characteristics and outcomes for patients with HER2-overexpressing breast cancer with brain metastases undergoing radiation therapy in the pre- and post adjuvant trastuzumab era

Background: Trastuzumab (H) has improved outcomes for patients with HER2 overexpressing (HER2+) breast cancer (BC) and thus increased the at-risk period for development of brain metastases (BM). In this study we describe the characteristics and outcomes of patients with HER2+BCBM who underwent stereotactic radiosurgery (SRS) or whole brain radiation (WBRT) as initial BM treatment (tx) in the pre- and the post adjuvant (adj) H era at MSKCC.

Methods: 100 consecutive pts with HER2+ BCBM who received SRS or WBRT from January 2001 to December 2011 were identified. Clinical, pathologic and tx information were obtained by retrospective review. Pt characteristics at the time of BM diagnosis (dx) and their associations with time from BM to death were evaluated by Kaplan-Meier (KM) curves, log-rank tests, and Cox proportional hazard models.

Results: The median age at BM dx was 54 yrs (range 26-79). 31% and 69% of pts received SRS and WBRT respectively. After the BM dx, 97% continued to receive systemic tx consisting of chemotherapy and/or anti-HER2 tx. 97% of pts received H for MBC and 17% received H in the adj setting (all after 2005). Patient characteristics were compared between pre-adj H (2001-2005) and post-adj H (2006-2011) cohorts. The only significant differences noted between the cohorts in univariate analysis were extra-CNS disease control and use of anti-HER2 therapy after BM dx: pre-adj H era pts had a higher likelihood of extra-CNS disease control (79.5% vs. 52%, p = 0.004) at BM dx and less use of anti-HER2 tx after BM dx (70% vs. 87.5%. p = 0.05). For all pts, the median follow-up for survivors was 33.5 mos (range 18-103). There were 79 deaths. The median survival from BM dx was 19.4 mos (95%CI: 15.5, 26.6). KM curves and log-rank tests showed significantly better survival from BM for pts with higher KPS, single BM, extra-CNS disease control, lack of neurologic sx at BM dx, initial presentation without LMD, use of lapatinib (ever), SRS as initial RT, and use of any anti-HER2 tx after BM dx. Multivariate analysis showed that higher KPS [HR 0.21 (0.09,0.53)], extra-CNS disease control [HR 2.89 (1.67, 5.00)], single BM [HR 4.73 (2.11,10.60)], use of anti-HER2 tx after BM dx [HR 0.30 (0.17,0.53)], asymptomatic status at BM dx [HR 3.69 (1.69,8.07)] were associated with improved survival from BM. Lack of neurologic sx at BM dx was significantly associated with longer survival from BM even after adjustment for other potentially confounding prognostic factors.

Conclusion: These data are mostly consistent with prior reports regarding prognostic factors and inform contemporary clinical trial design. In pts with HER2+BCBM where the majority were subsequently exposed to anti-HER2 and other systemic tx, presence of neurologic sx at BM dx was significantly associated with worse survival after BM dx. Prospective evaluation of screening brain MRI allowing for earlier detection, leading to more careful monitoring or pre-emptive tx of asymptomatic BM may be warranted. The observation of better extra-CNS disease control at BM dx among pts in the pre- adj H era was unexpected, is hypothesis generating, and requires independent confirmation.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P6-11-02.

Abstract P1-13-11: Adjuvant treatment of early-stage breast cancer with eribulin mesylate following dose-dense doxorubicin and cyclophosphamide: preliminary results from a phase 2, single-arm feasibility study

Background: Despite recent improvements in breast cancer outcomes, patients (pts) with high-risk, early-stage breast cancer continue to experience recurrences and death due to disease. Chemotherapy regimens with the ability to extend survival remain an important drug development goal. Eribulin mesylate has demonstrated antitumor activity and improved overall survival (OS) in pts with heavily pretreated, locally recurrent or metastatic breast cancer when compared to treatment of physician's choice. This study examines the feasibility of eribulin as adjuvant therapy following dose-dense (dd) doxorubicin (A) and cyclophosphamide (C) in patients with early-stage breast cancer.

Methods: Eligible pts have histologically confirmed, HER2-normal, stage I-III invasive breast cancer and adequate bone marrow, liver, and renal function. Treatment consists of dd AC (A 60mg/m2 IV; C 600mg/m2 IV) on Day 1 of each 14-day cycle x4 cycles, followed by eribulin mesylate 1.4mg/m2 IV over 2–5min on Days 1 and 8 every 21 days x4 cycles. Radiation/hormonal therapy were allowed per standard of care. The primary objective of feasibility is defined as the ability to complete 4 cycles of eribulin without a treatment-related dose delay (defined as &gt;2 days) or reduction. Feasibility rates will be reported for pts with and without growth factor use. Secondary/exploratory endpoints include evaluation of the safety via NCI-CTCAEv4 of 4 cycles of AC followed by 4 cycles of eribulin, and 3-year disease-free survival and OS.

Results: As of 5/22/12, 46 of 80 planned pts have been treated; 38 pts have had ≥1 dose of eribulin and are evaluable for eribulin-related toxicity. Pt characteristics are as follows: median age 50 yrs (27–65 yrs); 100% female; ECOG of 0=81.6%; breast cancer stage at study entry: stg 1: 7.5%; stg 2: 72.5%, stg 3: 20%. Select treatment-related AEs are reported as total (all cycles) and eribulin-related events; many AEs overlapped during treatment (Table).

Paclitaxel efficacy and toxicity in older women with metastatic breast cancer: combined analysis of CALGB 9342 and 9840

BACKGROUND

Two Cancer and Leukemia Group B (CALGB) studies were utilized to determine the efficacy and tolerability of paclitaxel (Taxol) in older patients with metastatic breast cancer.

PATIENTS AND METHODS

CALGB 9840 evaluated weekly paclitaxel (80 mg/m(2)) versus paclitaxel every 3 weeks (175 mg/m(2)); CALGB 9342 evaluated three doses of paclitaxel as follows: 175, 210 and 250 mg/m(2) each over 3 h every 3 weeks. Of the 1048 patients, paclitaxel was used first line in 57%. The groups: (i) <55 years (45%), (ii) 55-64 years (29%), and (iii) ≥65 years (26%).

RESULTS

Tumor response was also similar among age groups. First-line therapy (P = 0.0001) and better performance status (PS) (P = 0.018) were significantly related to higher response. Age did not significantly relate to overall survival (OS) or progression-free survival (PFS). First-line therapy, better PS, estrogen receptor positive status and a fewer number of metastatic sites were significantly related to improved OS and PFS. The grade ≥3 toxic effects that increased linearly with age were leucopenia (P = 0.0099), granulocytopenia (P = 0.022), anorexia (P = 0.028), bilirubin elevation (P = 0.0035) and neurotoxicity (P < 0.0001). Patients over 65 years receiving second-line therapy had the shortest time to neurotoxicity.

CONCLUSIONS

Older women with breast cancer derive similar efficacy from treatment with paclitaxel as younger women. Older women are at increased risk for specific toxic effects.

P5-19-11: Tesetaxel, an Oral Taxane, as First-Line Therapy for Women with Metastatic Breast Cancer

Background

Parenteral taxanes (docetaxel, paclitaxel) are among the most active agents in treating metastatic breast cancer (MBC). However, their use is limited by inherent or acquired multidrug resistance, hypersensitivity, and neurotoxicity. Tesetaxel is an advanced-generation, orally available taxane that is formulated as a capsule for oral administration and has a long terminal half-life in plasma (∼180 hrs). Unlike standard taxanes, tesetaxel is not a substrate for P-glycoprotein (P-gp), a major cause of taxane resistance. The drug is highly concentrated in cells that overexpress P-gp. In taxane-resistant breast cancer xenografts (DU4475), tesetaxel induced a 94% reduction in tumor size, substantially exceeding the activity of docetaxel and paclitaxel (46% and 26%, respectively). Neurotoxicity was also substantially lower with tesetaxel compared with equi-myelotoxic doses of docetaxel. Among more than 350 patients (pts), there have been no occurrences of hypersensitivity reactions. An initial phase 2 study as 2nd-line therapy for pts with MBC who progressed after multidrug anthracycline-containing regimens showed a 38% partial response (PR) rate using tesetaxel Q3 wks at a dose of 27–35 mg/m2. We conducted a Phase 2, open-label, multicenter study of the efficacy and safety of tesetaxel as first-line therapy in women with MBC.

Methods: Eligible pts have Stage IV, HER2−negative MBC; ECOG PS 0–1; and adequate organ function. No prior chemotherapy is allowed (other than 1 regimen in the adjuvant setting). Tesetaxel was administered orally Q3 wks at a starting dose of 27 mg/m2 with escalation to 35 mg/m2 as tolerated. No premedication for potential hypersensitivity was used. RECIST response rate was the primary endpoint. A Simon min-max two-stage design was used with a target response rate of 30% in 25 pts.

Results: To date, 20 women have been enrolled and treated. The median age was 62 years (range, 45–78). Time from diagnosis was &gt; 4 years in 5 pts and ≤ 4 years in 6; MBC was newly diagnosed in the remaining 9. Hormone receptor status was triple negative in 5 pts at diagnosis and 10 at the time of metastasis. The most common sites of metastasis were lung (13 pts) and bone (9). Prior treatment included hormonal therapy in 13 pts, adjuvant chemotherapy in 16 (most commonly, ACT), and radiotherapy in 9. Of 11 pts currently evaluable for response, PR was achieved in 6 (55%), with confirmation of response in 4 and an ongoing PR in 1 of the 2 pts with an unconfirmed PR. SD was observed in 2 and disease progression in 3. Neutropenia was the most common adverse event, affecting 50% of pts; Grade 3–4 occurrences were observed most often after escalation of the tesetaxel dose to 35 mg/m2. Single occurrences (Grade 1) of neuropathy and nail changes were reported. There were no occurrences of hypersensitivity.

Conclusions: Tesetaxel overcomes multiple disadvantages of standard parenteral taxanes and is highly active in 1st- and 2nd-line MBC. To date, overall response rates in these settings are 55% and 38%, respectively. In view of this, we have amended the trial to expand the initial cohort. Potential schedule-dependency will be examined in a future cohort with a newly developed weekly-times-3 schedule. Updated results in both cohorts will be presented.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P5-19-11.

P1-14-01: Randomized Phase II Trial of Weekly vs. q 2-Weekly vs. q 3-Weekly Nanoparticle Albumin-Bound Paclitaxel with Bevacizumab as First-Line Therapy for Metastatic Breast Cancer

Background: Nanoparticle albumin-bound paclitaxel (nab-P) 260 mg/m2 is superior to paclitaxel 175 mg/m2 (P) every 3 weeks (Gradishar et al. JCO 2005) in metastatic breast cancer (MBC), and weekly uninterrupted P is more effective than q3wk P in MBC (Seidman et al. JCO 2008). Bevacizumab (bev) nearly doubles response rate and time to progression (TTP) when added to P as 1st line therapy for MBC (Miller et al. NEJM 2007).

Methods: This open-label, phase II study randomized patients (pts) to nab-P at 260 mg/m2 q3wk (arm A) vs. 260 mg/m2 q 2wk with filgrastim (arm B) vs. 130 mg/m2 weekly uninterrupted (arm C), all with bev (15 mg/kg q 3 weeks arm A, 10 mg/kg q 2 weeks arms B and C). Patients were required to have measurable, HER2 negative MBC and no prior chemotherapy for MBC. The primary endpoints were response rate and toxicity.

Results: Of 212 pts randomized, 208 (75 arm A, 54 arm B, 79 arm C) were treated, with balanced demographics and baseline characteristics. The median age was 57 (range 29–85), 82% were postmenopausal and 89% had visceral disease (64% lung, 50% liver). ECOG PS 0:60%, 1:35%, 2:5%. 62% had prior neo-adjuvant or adjuvant chemotherapy for early stage disease: anthracycline: 54%, taxane: 38%. No significant differences in confirmed complete and partial response rates were noted (A: 40%, B: 44%, C: 46%). Median TTP was longer in Arm C (9.0 months) versus both arms B (6.3 months) and A (8.0 months), overall p=0.065. There were no differences in overall survival (Arm A: 21.3 months, Arm B: 19 months, Arm C: 25.3 months). As per protocol-specified stopping rule, arm B was closed early due to an unacceptable safety profile with significantly more grade ≥ 2 fatigue (B:57%, A: 39%, C:39%, p=0.048) and bone pain (B:19%, A:10%, C:4%, p=0.024). Sensory neuropathy was common; grades 2/3/4: Arm A: 29%/32%/1%, Arm B: 15%/50%/2%, Arm C: 27%/43%/1%). Sensory neuropathy was commonly readily reversible with dose delay and reduction. Febrile neutropenia occurred in &lt;2% of pts in all arms. Arm C patients experienced significantly less arthralgia compared with arms A and B, but dose delays were frequent (86% of pts) on this planned uninterrupted weekly schedule. Bevacizumab-related events were consistent with prior phase III trials of taxane/bev; there were no new safety signals.

Conclusions: Significant and similar antitumor activity was observed in all arms. Weekly nab-P with bev (arm C) resulted in longer TTP. Weekly nab-P with bev (arm C) appears to have the highest therapeutic index, however sensory neuropathy is limiting, suggesting that a 3 week on/1 week off schedule could be preferable and should be studied comparatively.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P1-14-01.