BACKGROUND Chemotherapy-induced peripheral neuropathy (CIPN) is a dose-limiting toxicity of several commonly used chemotherapy drugs including taxanes, vinca alkaloids, and platinum compounds. Development of CIPN is highly variable, both in self-reported symptoms and functional consequences, and can be severe enough to alter dose intensity. PURPOSE To describe the natural histories of both patient-reported symptoms of chemotherapy-induced peripheral neuropathy (CIPN) and functional impairments in breast cancer patients undergoing taxane-based chemotherapy. METHODS Thirty-three breast cancer patients (32 female/1 male; 47.8 ± 11.2 years; n=17 stage II/n=16 stage III) were enrolled. Patients completed self-reports of symptoms and function (e.g., EORTC QLQ-CIPN20) and objective measures of physical function (i.e., balance and gait testing) in an outpatient oncology clinic at five timepoints: (1) baseline - prior to starting chemotherapy, (2–4) before starting subsequent chemotherapy cycles, and (5) 1–3 months after receiving their last taxane infusion. RESULTS Significant negative changes in both patient-reported outcomes and objective functional measures were observed. Decreased balance was observed after the first chemotherapy cycle (28% increase in medial-lateral excursion of the center of pressure, p=0.016) and progressed with cumulative exposure (43% increase, p<0.001). Patients also demonstrated slower walking speeds (5% decrease, p=0.003) as they progressed through treatment. These functional deficits were mirrored with increased patient-reported symptom severity for all EORTC QLQ-CIPN20 subscales (all p<0.05). CONCLUSION This study longitudinally assessed patient-reported outcomes concurrently with balance and gait testing in patients undergoing taxane therapy. Taxane treatment was associated with the development of clinically-relevant problems in both CIPN symptoms and patient function.

Over 230,000 new cases of breast cancer are expected to be diagnosed in the United States in 2015. Taxane-based chemotherapy is often an effective treatment, but can also cause adverse symptoms in patients due to neurotoxicity. These side effects can impair postural control in patients; however, this instability has scarcely been quantified. The purpose of this pilot study was to gain insight into the natural history of postural instability in breast cancer patients being treated with taxane-based chemotherapy. Thirty-two breast cancer patients (31 female/ 1 male; 47.6 ± 11.2 yr; 16 stage II/ 16 stage III) completed eyes open and eyes closed quiet standing trials in the oncology clinic where they were being treated. These trials were collected at five timepoints throughout their chemotherapy treatment: (1) before initiating chemotherapy to provide a baseline, (2–4) before starting subsequent chemotherapy cycles, and (5) 1–3 months after receiving their last taxane infusion. After the first chemotherapy cycle, patients demonstrated increases in 95% confidence ellipse area of center of pressure (CoP) [45.2%, p=0.01] and root mean squared CoP excursion [18%, p=0.006] compared to baseline values for the eyes closed condition. These balance deficiencies progressed with cumulative taxane exposure. Postural instability persisted 1–3 months after completing chemotherapy with increases in 95% CoP ellipse area [86.8%, p=0.002], root mean squared CoP excursion [32.6%, p=0.001], and mean CoP velocity [30.4%, p=0.024]. The balance impairments demonstrated by patients in this study appear to be clinically relevant when compared to balance impairments previously reported in other patient populations.

Background: Preclinical data demonstrates that activation of RAS/MEK/ERK pathway in basal-like breast cancer (BLBC) leads to resistance to chemotherapy. Inhibiting MEK pathway was highly effective in BLBC models with intact PTEN. Conversely activated PI3K/AKT pathway (loss of PTEN which occurs in ∼ 30% of TNBC) led to resistance to MEK inhibition. We proposed to test the hypothesis that single agent trametinib (T) will demonstrate efficacy in a subset of TNBC and that addition of AKTi, GSK2141795 (G) will overcome resistance to T. Methods: This is a single arm, multicenter study through the ETCTN. Eligible patients (pts) with advanced TNBC, measurable disease with 1-3 prior chemotherapies received mandatory research biopsy and entered Part I of the study with T alone (2 mg Q day-28 days). At the point of progression pts received a mandatory second biopsy and moved to PART II of study with 1.5 mg of T + 50 mg of G. Optional research biopsy was performed at the point of progression on the combination. Restaging scans were done every 2 cycles. Blood samples were collected at baseline, cycle 2 and at progression. Results: 33 pts with median age 55 (35-71) from six cancer centers were enrolled to Part I (T alone) and 17 pts entered part II (T +G). Most common toxicities for pts on T alone included Gr1: diarrhea, rash, transaminitis, Gr 2: fatigue; Gr 3: thromboembolism. Of 31 evaluable pts on T alone, two pts (1 still on study after 8 cycles) had a partial response (PR) and one pt has stable disease after 8 cycles and remains on study. Of the sixteen evaluable patients on part II (T+G) one patient has an unconfirmed PR (34% reduction on RECIST). Common toxicities for the combination include: Gr1: diarrhea, nausea, vomiting, myelosuppression, rash, hypertension, transaminitis, Gr2: Rash, fatigue, mucositis, diarrhea, Gr 3: diarrhea. Eleven patients died on study (10-progression, 1-adverse event). Blood and tissue samples are being analyzed for whole genome sequencing, IHC for PTEN, Quantitative targeted absolute proteomics (QTAP) for kinome assay and RPPA for PTEN, PI3KCA, AKT, ERK and MEK. This study is currently closed to accrual for interim analysis for efficacy on part II. Conclusion: Trametinib alone and in combination with AKTi, GSK2141795 has limited efficacy in TNBC. Proposed correlatives in serial biopsies may identify biomarkers in the few responders and help identify other novel targets. Citation Format: Bhuvaneswari Ramaswamy, Ewa Mrozek, Maryam Lustberg, Robert Wesolowski, Rachel Layman, Mahmoud Abdel-Rasoul, Cynthia Timmers, Robyn Patrick, Jennifer Sexton, Erin Macrae, Charles Shapiro, Thomas Budd, Lyndsay Harris, Claudine Isaacs, Roohi Ismail-Khan, Claire Dees, Andrew Poklepovic, Micheal Grever, Helen Chen, Miguel Villalona, William Carson. NCI 9455: Phase II study of trametinib followed by trametinib plus AKT inhibitor,GSK2141795 in patients with advanced triple negative breast cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr LB-216.

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