Phase II study of propranolol feasibility with neoadjuvant chemotherapy in patients with newly diagnosed breast cancer

Propranolol regulates angiogenesis in pre-clinical models and reduces distant breast cancer (BC) metastases in observational studies. We assessed the feasibility of combining propranolol with neoadjuvant chemotherapy (NAC) in patients with BC. Women with clinical stage II–III BC undergoing NAC [weekly paclitaxel × 12, followed by dose-dense adriamycin/cyclophosphamide (AC) × 4] started propranolol 20 mg PO BID with paclitaxel #1, and increased to 80 mg extended release (ER) PO daily, as tolerated. The primary endpoint was to assess feasibility, defined as at least 75% of patients having at least 80% adherence to propranolol as prescribed. Secondary endpoints included identifying safety, rate of dose holds and modification, and rate of reaching 80 mg ER daily. The proposed sample size was 20 patients. From November 2012 to September 2015, ten patients were enrolled. Median age was 50.5 years (range, 44–67). All patients had hormone receptor-positive/HER2-negative breast cancer. Three women had grade I bradycardia that resulted in a 1-week delay in increasing the propranolol dose. Ninety percent of women reached the target propranolol dosing of 80 mg ER daily, and 70% took the target propranolol dose until the night before surgery. Of the 4 women who dose-reduced propranolol, 1 increased to the target propranolol dose. Mean adherence to propranolol dosing was 96% (range: 91–100%). All patients went to surgery. Our results support the feasibility of combining propranolol (up to 80 mg ER) with neoadjuvant taxane/anthracycline-based chemotherapy.


Introduction
Angiogenesis is essential in the metastatic potential of breast cancer cells [1,2]. The FDA approval for anti-angiogenic monoclonal antibody bevacizumab was later revoked for significant side effects with minimal clinical benefit [3][4][5]. Thus, there remains a need to identify well-tolerated and inexpensive anti-angiogenic agents for the treatment of breast cancer.
There are pre-clinical data demonstrating that beta blockers offer this advantage by impacting the primary breast cancer environment. In the absence of a beta blocker, norepinephrine activates cellular beta-adrenergic receptors, triggering transcription factors to regulate tumor cell proliferation and apoptosis inhibition and stimulating the migration and chemotaxis of triple-negative (TN) breast cancer cells [14,15]. This process is completely inhibited by beta-2 blockers and partially reduced by beta-1 blockers in TN and estrogen receptor-positive cell lines [16]. These findings support evaluating propranolol as an angiogenic modulator in breast cancer. We conducted a phase II trial to evaluate whether combining propranolol with neaoadjuvant taxane/ anthracycline-based chemotherapy was feasible and to assess associated safety and tolerability.

Participants
Patients were women diagnosed with breast cancer being treated at Columbia University Irving Medical Center (CUIMC) who were administered neoadjuvant propranolol along with 12 cycles of weekly paclitaxel followed by 4 cycles of dose-dense adriamycin and cyclophosphamide (AC) biweekly. Patients with any subtype of breast cancer were eligible, and if a patient had HER2-positive breast cancer, trastuzumab and pertuzumab would be given along with paclitaxel. Inclusion criteria included the following: (a) English or Spanish speaking women at least 18 years old, (b) any stage invasive breast cancer with a tumor size > 1 cm, (c) heart rate (HR) > 60 beats per minute (bpm), (d) systolic blood pressure (SBP) > 100 mmHg, and (e) echocardiogram with ejection fraction (EF) > 50%. Exclusion criteria included the following: (a) QTc prolongation defined by > 470 ms on electrocardiogram (ECG); (b) first degree atrioventricular (AV) block on ECG as indicated by PR interval lengthening > 200 ms, seconddegree heart block, or third-degree heart block; (c) current or recent (within 3 months) beta blocker treatment; or (d) history of asthma, given concern for beta-blockade. Patients provided written informed consent. This study was approved by the Institutional Review Board at CUIMC and was listed on clincialtrials.gov (NCT01847001).

Study procedure and treatment
All trial participants completed a baseline physical exam, echocardiogram, and ECG. Once enrolled, patients started propranolol 20 mg PO BID (40 mg daily) the same week that they initiated paclitaxel. Patients received paclitaxel every week for 12 weeks and continued taking propranolol daily, with up-titration to a maximum dose of 80 mg extended release (ER) by mouth (PO) as tolerated. The propranolol dose level was increased every 2 weeks depending on the patient's AEs and vital signs ( Table 1). Every other week, patients returned for a physical exam, an assessment of AEs, and a pill count check. At the completion of the 12 weeks of paclitaxel, patients underwent a second ECG and echocardiogram. Subsequently, they began a 4-cycle treatment of AC every 2 weeks, while continuing to take propranolol daily. A third ECG and echocardiogram were performed upon completion of AC. Patients took daily propranolol until the night before surgery.

Clinico-pathologic characteristics
Clinical and pathologic staging were determined based on the American Joint Committee on Cancer (AJCC) TNM Staging Manual, 7th edition. Hormone receptor positivity was defined as estrogen or progesterone receptor positivity of ≥ 1% expression on any biopsy in accordance with the American Society of Clinical Oncology/College of American Pathologist (ASCO/CAP) guidelines [17]. HER2-positivity was defined by ASCO-CAP guidelines [18]. Race/ ethnicity was self-reported as Asian, Black, Hispanic, or non-Hispanic white.

Adverse events
All AEs were documented and graded per CTCAE v. 4.0. AEs were categorized into cardiac and non-cardiac toxicities. Grade I cardiac toxicities resulted in propranolol being held at the same dose level or dose-reduced per physician discretion for 2 weeks, at which point toxicity was re-assessed; if the toxicity had resolved, the propranolol dose could be up-titrated one level (Table 1). Grade II or higher cardiac toxicities would result in the patient being removed from the study. For noncardiac toxicities, grade I and II AEs resulted in continuing up-titration of propranolol every 2 weeks until 80 mg ER PO daily, per physician discretion. Grade III or IV non-cardiac toxicities related to propranolol resulted in propranolol dose reduction by one level, and re-assessment at 2 weeks, until the toxicity was deemed to be ≤grade II. Chemotherapy doses were delayed or dose-reduced if any of the following toxicities occurred: (1) grade III or IV febrile neutropenia, as defined by temperature >38.5 °C and absolute neutrophil count (ANC) <1000/mm 3 , (2) platelet nadir <50,000, (3) grade III or IV neuropathy, or (4) grade III or IV non-hematologic toxicities, excluding neuropathy and cardiac toxicities. AEs were categorized based on their relationship to propranolol, chemotherapy, both, or neither. The study was monitored by the Herbert Irving Comprehensive Cancer Center Data and Safety Monitoring Board.

Statistical analysis
The primary endpoint was to assess the feasibility of giving neoadjuvant propranolol in combination with cytotoxic chemotherapy. The combination was deemed feasible if at least 75% of patients were adherent with taking >80% of propranolol as prescribed (non-adherence/medication possession ratio of <20%) [19,20]. Patient adherence was determined by the proportion of pills taken to the expected number of pills at biweekly pill checks. Dose holds and discontinuations were not considered as patient non-adherence. Pills that were not returned were assumed to be taken. The proposed sample size was 20 patients, based on an accrual rate of 2 patients per month over a 12-month period. Secondary endpoints were the following: (a) safety and tolerability of neoadjuvant propranolol with chemotherapy, (b) dose modifications and holds, and (c) ability to achieve the 80 mg ER PO dose any time during the study.

Baseline characteristics
Between November 2012 to September 2015, 10 women consented to the study. The trial was stopped early due to slow accrual. The demographic characteristics are described in Table 2. At baseline, the median age was 50.5 years (range, 44-67) and the median body mass index (BMI) was 26.2 kg/m 2 (range, 18.9-36.4 kg/m 2 ). Of the 10 patients, 1 patient self-identified as Asian, 1 as black, 5 as Hispanic, and 3 as non-Hispanic white. Six patients were premenopausal and 4 were postmenopausal. The majority of tumors were invasive ductal cancer (90%), stage II (70%), and poorly differentiated (60%). All 10 patients had hormone receptor-positive/HER2-negative breast tumors, with hormone receptor positivity ≥ 10%.

Feasibility, safety, and adherence
All 10 patients had greater than 90% adherence rate to propranolol dosing as prescribed over the entire study period. The mean patient adherence was 96% (range: 91-100%). Of the 10 women, 9 (90%) reached the target propranolol dosing of 80 mg ER daily in a median of 28 days (range, 25-49 days). Six of these 9 women (66%) took 80 mg ER until the night before surgery without any AEs necessitating a decrease in dose. The other 3 required a dose reduction due to grade II fatigue after AC #2, grade II QTc prolongation, or grade II intermittent fevers after AC #4. For the patient with grade II fevers, the patient was hemodynamically stable, and the dose was reduced per physician discretion. Thus, 40% of women required a dose reduction due to AEs. Of the 3 patients who dose-reduced from 80 mg ER daily, 1 patient returned to taking 80 mg ER daily and continued that dose until the night prior to surgery. One woman had continuation of grade II fatigue and stopped propranolol after AC #3. She did not proceed with AC #4, however, this was not deemed to be related to propranolol. The other patient completed the study period at 30 mg PO BID. Of the 10 women, only 1 woman did not reach the target propranolol dosing and completed the study at 20 mg BID, which was dose reduced from 30 mg BID because of grade I dizziness (per physician discretion). Overall, 70% of the patients, including the patient who temporarily dosed reduced, were able to take the target dose of propranolol 80 mg ER daily until the night before surgery. All women completed 12 weeks of paclitaxel, except for one woman who was switched to nab-paclitaxel at week 3 due to a transfusion-related, non-anaphylactic reaction and another woman had her fourth dose of paclitaxel postponed one week due to a grade III decreased absolute neutrophil count (ANC). Three of the 10 patients (30%) postponed, but completed, one cycle of AC for 1-2 weeks due to colitis, fatigue, or a central line infection. One of the three women omitted AC #4 due to grade II tremor, weakness, and dyspnea. All reasons for delay were related to chemotherapy, except for fatigue which was deemed possibly related to propranolol for 1 patient. Overall, 90% of women were able to complete weekly taxane × 12, followed by dose-dense AC.

Cardiac adverse events
Of the reported toxicities, the only cardiac AE related to propranolol use was bradycardia. Three women had a onetime measurement of grade I bradycardia that resulted in 2 women delaying increasing the dose of propranolol by 1 week. The third patient's bradycardia had resolved after initial measurement, so no changes were made to propranolol dosing. The bradycardia occurred at the doses of 20 mg BID, 30 mg BID, and 80 mg daily, and all women were able to up-titrate to or remain at 80 mg daily. Other reported cardiac AEs included chest tightness, palpitations, and a right atrial thrombus, but all were deemed not related to propranolol.

Pathologic response
All patients in the trial had operable breast cancer. At the time of surgery, 1 patient (10%) had a pathologic complete response (pT0pN0), 1 (10%) had residual tumor in the lymph nodes, 4 (40%) had residual tumor in the breast, and 4 (40%) had residual tumor in both the breast and lymph nodes. The patient with the pathologic complete response had grade III invasive ductal carcinoma, T1N1, and completed the course of 80 mg daily of propranolol without a dose reduction.

Discussion
The primary goal was to evaluate the feasibility of combining propranolol with taxane/anthracycline-based neoadjuvant chemotherapy in women with operable breast cancer. Our results demonstrate that propranolol use (up to 80 mg ER daily) in this population is safe and tolerable. The majority of women were able to take propranolol at the target dose without significant symptoms and with acceptable adherence. Women who had to dose reduce because of propranolol-related symptoms were mostly able to resume the target dose and did not have prolonged symptoms. The majority of the women who were not able to tolerate 80 mg ER of propranolol were able to do so at a lower dose. One patient experienced grade II fatigue and weakness possibly related to propranolol or chemotherapy after AC #3, discontinuing both early. All patients proceeded to surgery. Pathologic response was descriptive.
Propranolol has been studied as pre-operative therapy for many types of cancers, including breast, melanoma, prostate, liver, gastric, and thyroid [21][22][23][24][25]. While this evaluated administering propranolol with chemotherapy, propranolol was associated with a reduction in intratumoral mesenchymal proliferation and promotion of immune cell infiltration, in a window of opportunity trial for patients with operable breast cancer. These findings are concordant with other recent studies which suggest that concurrent use of propranolol improves tumor response to immunotherapy by altering the tumor microenvironment through the upregulation of cytotoxic T cells and inhibition of regulatory T cells and myeloid-derived suppressor cells [26][27][28][29]. Additional anti-metastatic properties of propranolol include impacting catecholamine-associated rates of cancer cell proliferation, migration, invasion, and angiogenesis [30]. Thus, in addition to the potential of combining propranolol with chemotherapy, there is a rationale for other potential combinations, including checkpoint inhibition.
Studying the feasibility and efficacy of utilizing repurposed drugs is beneficial due to lower cost, potentially decreased risk, and more rapid transition into clinical practice than the development of new cancer drugs [31]. Currently, other medications with non-cancer indications that are being tested in the adjuvant setting for breast cancer include metformin and aspirin due to a strong pre-clinical and observational rationale [32][33][34][35][36]. Both are being evaluated in large adjuvant trials to determine their potential benefit in reducing the rates of breast cancer recurrence.
One strength of this study was that frequent pill and symptom checks allowed for close monitoring of propranolol adherence and associated symptoms. While there were a limited number of patients in this study, the study enrolled a racially and ethnically diverse patient population, highlighting its generalizability. This study was stopped early due to slow accrual. Limitations to study accrual were not due to patients being ineligible; rather, patients having limited enthusiasm about determining safety and tolerability with an already established oral medication and concerns about potential toxicity. However, enrollment could potentially be more robust in future multi-center trials, given the increasing pre-clinical and clinical data supporting the evaluation of propranolol in breast cancer, as well as tolerability in this study. Given our small sample size, we were unable to draw conclusions related to changes in HR, SBP, and DBP from baseline and outcomes related to propranolol efficacy.
In conclusion, our study suggests that neoadjuvant administration of propranolol on a daily basis over several months in combination with taxane/anthracycline-based chemotherapy is feasible and tolerable for operable breast cancer. Propranolol use should be considered safe to evaluate in larger studies to determine whether it improves clinical outcomes, including disease-free survival, as well as predictive biomarkers of response.