Erika Paige Hamilton

Targeting CDK4/6 in patients with cancer

The cyclin D-cyclin dependent kinase (CDK) 4/6-inhibitor of CDK4 (INK4)-retinoblastoma (Rb) pathway controls cell cycle progression by regulating the G1-S checkpoint. Dysregulation of the cyclin D-CDK4/6-INK4-Rb pathway results in increased proliferation, and is frequently observed in many types of cancer. Pathway activation can occur through a variety of mechanisms, including gene amplification or rearrangement, loss of negative regulators, epigenetic alterations, and point mutations in key pathway components. Due to the importance of CDK4/6 activity in cancer cells, CDK4/6 inhibitors have emerged as promising candidates for cancer treatment. Moreover, combination of a CDK4/6 inhibitor with other targeted therapies may help overcome acquired or de novo treatment resistance. Ongoing studies include combinations of CDK4/6 inhibitors with endocrine therapy and phosphatidylinositol 3-kinase (PI3K) pathway inhibitors for hormone receptor-positive (HR+) breast cancers, and with selective RAF and MEK inhibitors for tumors with alterations in the mitogen activated protein kinase (MAPK) pathway such as melanoma. In particular, the combination of CDK4/6 inhibitors with endocrine therapy, such as palbociclibs recent first-line approval in combination with letrozole, is expected to transform the treatment of HR+ breast cancer. Currently, three selective CDK4/6 inhibitors have been approved or are in late-stage development: palbociclib (PD-0332991), ribociclib (LEE011), and abemaciclib (LY2835219). Here we describe the current preclinical and clinical data for these novel agents and discuss combination strategies with other agents for the treatment of cancer.

Abstract S1-04: Avelumab (MSB0010718C), an anti-PD-L1 antibody, in patients with locally advanced or metastatic breast cancer: A phase Ib JAVELIN solid tumor trial

Background: The programmed death-1 receptor (PD-1) and its ligand (PD-L1) are key therapeutic targets in the reactivation of the immune response against cancer. Avelumab* (MSB0010718C) is a fully human anti-PD-L1 IgG1 antibody being investigated in clinical trials. We report clinical activity of avelumab in a cohort of patients (pts) with locally advanced (LA) or metastatic breast cancer (MBC) refractory to or progressing after standard-of-care therapy (NCT01772004). Methods: Pts received avelumab at 10 mg/kg Q2W until confirmed progression, unacceptable toxicity, or any criterion for withdrawal occurred. Tumors were assessed every 6 wks (RECIST 1.1). Unconfirmed best overall response was evaluated. Adverse events (AEs) were graded by NCI-CTCAE v4.0. Biopsy or surgical specimens were collected within 90 days prior to 1st dose of avelumab for biomarker analyses. Tumor PD-L1 expression was assessed by immunohistochemistry using various cutoff criteria. Results: As of 27 Feb 2015, 168 pts (167 female, 1 male) with MBC, including ductal (56.5%), carcinoma NOS (9.5%), lobular (3.6%), or other (30.4%), were treated with avelumab and followed for a median of 10 mo (range 6-15). Median age was 55y (range 31-81), ECOG performance status was 0 (49.4%) or 1 (50.6%), and pts had received a median of 3 prior therapies for LA/M disease (range 0-10; pts must have received prior treatment with taxane and anthracycline, unless contraindicated). Pts were HER2–/ER+ or PR+ (69 [41.1%]), triple negative (TNBC = HER2–/ER–/PR–; 57 [33.9%]), HER2+ (26 [15.5%]), or had unknown biomarker status (16 [9.5%]). Median duration of treatment was 8 wks (range 2-50), and 9 pts (5.4%) remained on avelumab. Any grade treatment-related treatment-emergent AEs (TEAEs) occurred in 120 pts (71.4%); the most common (>10%) were fatigue (33 [19.6%]), nausea (24 [14.3%]), and infusion-related reactions (20 [11.9%]). Treatment-related grade ≥3 TEAEs occurred in 24 pts (14.3%) and included (≥1%) fatigue, anemia, increased GGT, and autoimmune hepatitis (each 3 [1.8%]), and arthralgia (2 [1.2%]). There were 2 treatment-related deaths (acute liver failure, respiratory distress). Unconfirmed objective response rate (ORR) in the entire cohort was 5.4% (9 pts; 95% CI: 2.5, 9.9), with 1 CR and 8 PRs. Five of 9 responses were ongoing at time of cutoff. Stable disease was observed in additional 40 pts (23.8%), for an overall disease control rate of 29.2%. Evidence of tumor reduction by ≥30% was seen in 15 pts (8.9%). There were responders in all biomarker subgroups, including 5 PRs in TNBC (n=57 [8.8%; 95% CI: 2.9, 19.3]). PD-L1 expression was evaluable in 136 pts. Among all pts with PD-L1 expressing immune cells within the tumor, 33.3% (4 of 12) had PRs. In pts with TNBC who had PD-L1+ immune cells within the tumor, 44.4% (4 of 9) had PRs, compared with 2.6% (1 of 39) for TNBC and PD-L1– immune cells. Conclusions: Avelumab showed an acceptable safety profile and had clinical activity in a subset of pts with MBC. In pts with TNBC, presence of PD-L1 expressing immune cells within the tumor may be associated with clinical responses to avelumab. Further analyses of PD-L1 expression and clinical activity of avelumab in MBC are ongoing. *Proposed INN. Citation Format: Dirix LY, Takacs I, Nikolinakos P, Jerusalem G, Arkenau H-T, Hamilton EP, von Heydebreck A, Grote H-J, Chin K, Lippman ME. Avelumab (MSB0010718C), an anti-PD-L1 antibody, in patients with locally advanced or metastatic breast cancer: A phase Ib JAVELIN solid tumor trial. [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 S1-04.

Safety and efficacy of aerobic training in operable breast cancer patients receiving neoadjuvant chemotherapy: A phase II randomized trial

Abstract Background. To evaluate the safety and efficacy of moderate-to-high intensity aerobic training in breast cancer patients receiving neoadjuvant chemotherapy. Methods. Twenty patients with stage IIB–IIIC operable breast cancer were randomly assigned to receive doxorubicin plus cyclophosphamide (AC) or AC in combination with aerobic training (AC + AET) (n = 10/group) for 12 weeks. The AC+ AET group performed three supervised aerobic cycle ergometry sessions per week at 60%–100% of exercise capacity (VO2peak). Safety outcomes included exercise testing as well as treatment- and exercise training-related adverse events (AEs), whereas efficacy outcomes included cardiopulmonary function and patient-reported outcomes (PROs) as measured by a cardiopulmonary exercise test (CPET) and Functional Assessment of Cancer Therapy-Breast (FACT-B) scale. Results. Twelve non-significant ECG abnormalities and three non-life threatening events occurred during CPET procedures. One AE was reported during aerobic training. There were no significant between group differences for clinician-documented events (e.g. pain, nausea) or hematological parameters (ps > 0.05). Attendance and adherence rates to aerobic training were 82% and 66%, respectively. Intention-to-treat analysis indicated that VO2peak increased by 2.6 ± 3.5 ml/kg/min (+ 13.3%) in the AC + AET group and decreased by 1.5 ± 2.2 ml/kg/min (−8.6%) in the AC group (between group difference, p = 0.001). FACT-B increased 11.1 points in the AC + AET group compared to a 1.5 point decrease in the AC group (between group difference, p = 0.685). Conclusion. Moderate-to-high intensity aerobic training when conducted with one-on-one supervision is a safe adjunct therapy associated with improvements in cardiopulmonary function and select PROs during neoadjuvant chemotherapy.

αB-Crystallin: A Novel Regulator of Breast Cancer Metastasis to the Brain

Purpose: Basal-like breast tumors are typically (ER/PR/HER2) triple-negative and are associated with a high incidence of brain metastases and poor clinical outcomes. The molecular chaperone αB-crystallin is predominantly expressed in triple-negative breast cancer (TNBC) and contributes to an aggressive tumor phenotype in preclinical models. We investigated the potential role of αB-crystallin in brain metastasis in TNBCs. Experimental Design: αB-crystallin expression in primary breast carcinomas and brain metastases was analyzed by immunohistochemistry among patients with breast cancer with brain metastases. αB-crystallin was overexpressed or silenced in two different TNBC cell lines. The effects on cell adhesion to human brain microvascular endothelial cells (HBMEC) or extracellular matrix proteins, transendothelial migration, and transmigration across a HBMEC/astrocyte coculture blood–brain barrier (BBB) model were examined. In addition, the effects of overexpressing or silencing αB-crystallin on brain metastasis in vivo were investigated using orthotopic TNBC models. Results: In a cohort of women with breast cancer brain metastasis, αB-crystallin expression in primary breast carcinomas was associated with poor overall survival and poor survival after brain metastasis, even among patients with TNBC. Stable overexpression of αB-crystallin in TNBC cells enhanced adhesion to HBMECs, transendothelial migration, and BBB transmigration in vitro, whereas silencing αB-crystallin inhibited these events. αB-crystallin promoted adhesion of TNBC cells to HBMECs, at least in part, through an α3β1 integrin–dependent mechanism. αB-crystallin overexpression promoted brain metastasis, whereas silencing αB-crystallin inhibited brain metastasis in orthotopic TNBC models. Conclusion: αB-crystallin is a novel regulator of brain metastasis in TNBC and represents a potential biomarker and drug target for this aggressive disease. Clin Cancer Res; 20(1); 56–67. ©2013 AACR.

Phase I clinical trial of HER2-specific immunotherapy with concomitant HER2 kinase inhibtion

BackgroundPatients with HER2-overexpressing metastatic breast cancer, despite initially benefiting from the monoclonal antibody trastuzumab and the EGFR/HER2 tyrosine kinase inhibitor lapatinib, will eventually have progressive disease. HER2-based vaccines induce polyclonal antibody responses against HER2 that demonstrate enhanced anti-tumor activity when combined with lapatinib in murine models. We wished to test the clinical safety, immunogenicity, and activity of a HER2-based cancer vaccine, when combined with lapatinib.MethodsWe immunized women (n = 12) with metastatic, trastuzumab-refractory, HER2-overexpressing breast cancer with dHER2, a recombinant protein consisting of extracellular domain (ECD) and a portion of the intracellular domain (ICD) of HER2 combined with the adjuvant AS15, containing MPL, QS21, CpG and liposome. Lapatinib (1250 mg/day) was administered concurrently. Peripheral blood antibody and T cell responses were measured.ResultsThis regimen was well tolerated, with no cardiotoxicity. Anti-HER2-specific antibody was induced in all patients whereas HER2-specific T cells were detected in one patient. Preliminary analyses of patient serum demonstrated downstream signaling inhibition in HER2 expressing tumor cells. The median time to progression was 55 days, with the majority of patients progressing prior to induction of peak anti-HER2 immune responses; however, 300-day overall survival was 92% (95% CI: 77-100%).ConclusionsdHER2 combined with lapatinib was safe and immunogenic with promising long term survival in those with HER2-overexpressing breast cancers refractory to trastuzumab. Further studies to define the anticancer activity of the antibodies induced by HER2 vaccines along with lapatinib are underway.Trial registryClinicalTrials.gov NCT00952692

Phosphatidylinositol 3-kinase pathway activation in breast cancer brain metastases

IntroductionActivation status of the phosphatidylinositol 3-kinase (PI3K) pathway in breast cancer brain metastases (BCBMs) is largely unknown. We examined expression of phospho(p)-AKT, p-S6, and phosphatase and tensin homologue (PTEN) in BCBMs and their implications for overall survival (OS) and survival after BCBMs. Secondary analyses included PI3K pathway activation status and associations with time to distant recurrence (TTDR) and time to BCBMs. Similar analyses were also conducted among the subset of patients with triple-negative BCBMs.Methodsp-AKT, p-S6, and PTEN expression was assessed with immunohistochemistry in 52 BCBMs and 12 matched primary BCs. Subtypes were defined as hormone receptor (HR)+/HER2-, HER2+, and triple-negative (TNBC). Survival analyses were performed by using a Cox model, and survival curves were estimated with the Kaplan-Meier method.ResultsExpression of p-AKT and p-S6 and lack of PTEN (PTEN-) was observed in 75%, 69%, and 25% of BCBMs. Concordance between primary BCs and matched BCBMs was 67% for p-AKT, 58% for p-S6, and 83% for PTEN. PTEN- was more common in TNBC compared with HR+/HER2- and HER2+. Expression of p-AKT, p-S6, and PTEN- was not associated with OS or survival after BCBMs (all, P > 0.06). Interestingly, among all patients, PTEN- correlated with shorter time to distant and brain recurrence. Among patients with TNBC, PTEN- in BCBMs was associated with poorer overall survival.ConclusionsThe PI3K pathway is active in most BCBMs regardless of subtype. Inhibition of this pathway represents a promising therapeutic strategy for patients with BCBMs, a group of patients with poor prognosis and limited systemic therapeutic options. Although expression of the PI3K pathway did not correlate with OS and survival after BCBM, PTEN- association with time to recurrence and OS (among patients with TNBC) is worthy of further study.

Phase II Trial of Dasatinib in Patients with Metastatic Breast Cancer Using Real-Time Pharmacodynamic Tissue Biomarkers of Src Inhibition to Escalate Dosing

Purpose: A phase II study of dasatinib, an inhibitor of multiple oncogenic tyrosine kinases including Src, was conducted to evaluate 16-week progression-free rate and tolerability in patients with previously treated metastatic breast cancer (MBC). Real-time assessment of potential tissue biomarkers of Src inhibition was used to optimize dosing. Experimental Design: Eligibility criteria required that patients have measurable MBC, biopsiable tumor, and unlimited prior therapies. For the analysis of change in protein biomarkers of Src inhibition, focal adhesion kinase, paxillin, and p-Src, patients underwent metastatic biopsies at baseline and 4 weeks. Patients who tolerated the starting dose of dasatinib (50 or 70 mg orally twice daily) for the first 28-day cycle, and displayed suboptimal Src inhibition, were escalated to a higher dose (70 or 100 mg). Results: The trial was closed early with 31 patients because of a statistical boundary that required at least 4 (13%) patients without disease progression to continue accrual. These 31 patients had a median of 2 prior lines of chemotherapy for MBC. The most notable toxicity was pleural effusions in 16 patients (52%). Twenty patients had evaluable metastatic biopsies. None of the tumors showed the predefined optimal level of Src inhibition at week 4. Conclusions: Single-agent dasatinib did not exhibit significant antitumor activity in patients with heavily pretreated MBC. There were no clinically meaningful decreases before and after dasatinib exposure between exploratory tissue biomarkers of Src inhibition which may be attributable to challenges in defining biomarker endpoints for multitargeted tyrosine kinase inhibitors. Clin Cancer Res; 17(18); 6061–70. ©2011 AACR.

Abstract P2-11-06: Safety and clinical activity of atezolizumab (anti-PDL1) in combination with nab-paclitaxel in patients with metastatic triple-negative breast cancer

Background: Metastatic triple-negative breast cancer (mTNBC) is associated with poor prognosis, and chemotherapy remains the mainstay of treatment. Cancer immunotherapy represents a promising treatment approach for mTNBC, which is characterized by a high mutation rate, increased levels of tumor-infiltrating lymphocytes and high programmed death ligand-1 (PD-L1) expression levels. Atezolizumab (atezo; MPDL3280A) is a humanized monoclonal antibody that can restore tumor-specific T-cell immunity by inhibiting the binding of PD-L1 to PD-1. Atezo has demonstrated durable responses as monotherapy in mTNBC (Emens et al, AACR 2015). In addition, high objective response rates (ORRs) and durable responses have been observed with atezo plus chemotherapy in patients with non-small cell lung cancer (Liu et al, ASCO 2015). This study is the first combination trial of a checkpoint inhibitor with chemotherapy in patients with mTNBC. Methods: This arm of a multicenter, multi-arm Phase Ib study (NCT01633970) evaluated atezo in combination with weekly nab-paclitaxel in patients with mTNBC. Primary endpoints were safety and tolerability, with secondary endpoints of PK and clinical activity. Key eligibility criteria included measurable disease, ECOG PS 0/1 and ≤ 2 prior cytotoxic regimens. Patients received atezo 800 mg q2w (days 1 and 15) with nab-paclitaxel 125 mg/m2 q1w (days 1, 8 and 15) for 3 weeks in 4-week cycles, continued until loss of clinical benefit. If nab-paclitaxel was discontinued due to toxicity, atezo could be continued as monotherapy. ORR was assessed by RECIST v1.1. PD-L1 expression was scored at 4 diagnostic levels based on PD-L1 staining on tumor cells and tumor-infiltrating immune cells with the SP142 immunohistochemistry assay. Results: As of February 10, 2015, 11 patients were evaluable for safety. All patients were women with a median age of 58 y (range, 32-75 y). No unexpected or dose-limiting toxicities were observed. The median duration of safety follow-up was 79 days (range, 27-182 days). The efficacy-evaluable population consisted of 5 patients who had ≥ 1 scan and ≥ 3 months follow-up. Four PRs and 1 SD were observed. By the next data cutoff of June 15, 2015, 21 patients will have been enrolled (7 in the safety cohort and 14 in the expansion cohort). All patients in the expansion cohort were required to undergo serial biopsies for correlative analyses. Approximately 21 and 19 patients will be evaluable for safety and efficacy, respectively. Updated safety, efficacy and biomarker data will be presented. Conclusions: Preliminary results indicate that the combination of atezo plus nab-paclitaxel is tolerable with promising activity in patients with mTNBC. Based on these results and the observed activity of single-agent atezo in these patients, the combination of atezo and nab-paclitaxel is being evaluated in a Phase III study (NCT02425891) of patients with previously untreated mTNBC. Sponsor: Genentech, Inc. ClinicalTrials.gov: NCT01633970. Citation Format: Adams S, Diamond J, Hamilton E, Pohlmann P, Tolaney S, Molinero L, Zou W, Liu B, Waterkamp D, Funke R, Powderly J. Safety and clinical activity of atezolizumab (anti-PDL1) in combination with nab-paclitaxel in patients with metastatic triple-negative 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 P2-11-06.

Safety of Bevacizumab in Patients with Metastatic Breast Cancer

Five randomized phase III trials – AVF2119g, E2100, AVADO, RIBBON-1, and RIBBON-2 – have reported data on the efficacy and safety of bevacizumab, combined with a variety of chemotherapy agents and in various settings, in patients with metastatic breast cancer (MBC). The E2100 trial demonstrated a significant improvement in progression-free survival according to the independent review facility, from 5.8 to 11.3 months when bevacizumab was combined with paclitaxel (p < 0.0001) as first-line therapy in patients with HER2-nonamplified MBC; subsequent trials of bevacizumab as first-line (AVADO, RIBBON-1) and second-line (RIBBON-2) therapy for patients with HER2-nonamplified MBC have also met their primary end point of prolonging progression-free survival (PFS). Accumulating safety data for bevacizumab in MBC show that it is generally well tolerated and associated with predictable adverse events, including hypertension and proteinuria. The majority of adverse events are mild and manageable, but bevacizumab is also associated with some severe toxicities. The management of bevacizumab-related adverse events in MBC has improved with increased experience. This review summarizes bevacizumab efficacy in MBC and focuses on bevacizumab-related toxicities as reported in 5 phase III clinical trials. Current adverse event management strategies, based on guidelines and experience from these trials, are outlined.

New perspectives on zoledronic acid in breast cancer: potential augmentation of anticancer immune response.

A small subset of T cells (gamma–delta T cells) is able to recognize phosphoantigens that are overexpressed in some cancer cells and may selectively target and kill cancer cells with high levels of phosphoantigen. Moreover, nitrogen-containing bisphosphonates, such as zoledronic acid, are able to induce accumulation of specific phosphoantigens in some cancer cells. A recent preclinical study showed that gamma–delta T cells effectively targeted and killed zoledronic acid-treated estrogen-receptor-positive breast cancer cells. These new data provide growing insight into a potential mechanism of action for some of the anticancer activity demonstrated by zoledronic acid in breast cancer clinical trials.