Akshara Raghavendra

CDK4/6 and autophagy inhibitors synergistically induce senescence in Rb positive cytoplasmic cyclin E negative cancers

Deregulation of the cell cycle machinery is a hallmark of cancer. While CDK4/6 inhibitors are FDA approved (palbociclib) for treating advanced estrogen receptor-positive breast cancer, two major clinical challenges remain: (i) adverse events leading to therapy discontinuation and (ii) lack of reliable biomarkers. Here we report that breast cancer cells activate autophagy in response to palbociclib, and that the combination of autophagy and CDK4/6 inhibitors induces irreversible growth inhibition and senescence in vitro, and diminishes growth of cell line and patient-derived xenograft tumours in vivo. Furthermore, intact G1/S transition (Rb-positive and low-molecular-weight isoform of cyclin E (cytoplasmic)-negative) is a reliable prognostic biomarker in ER positive breast cancer patients, and predictive of preclinical sensitivity to this drug combination. Inhibition of CDK4/6 and autophagy is also synergistic in other solid cancers with an intact G1/S checkpoint, providing a novel and promising biomarker-driven combination therapeutic strategy to treat breast and other solid tumours.

T-DM1 Activity in Metastatic Human Epidermal Growth Factor Receptor 2–Positive Breast Cancers That Received Prior Therapy With Trastuzumab and Pertuzumab

Purpose Ado-trastuzumab emtansine (T-DM1) is currently approved for treatment in patients with human epidermal growth factor receptor 2 (HER2)-positive, metastatic breast cancer (MBC) who previously received trastuzumab and a taxane. However, there are no data on the activity of T-DM1 in patients who received prior pertuzumab, which is now included as standard first-line therapy. The goal of this study was to assess the efficacy of T-DM1 in routine clinical practice in a contemporary patient population that received both prior trastuzumab and pertuzumab. Patients and Methods We identified all patients with HER2-positive MBC who received T-DM1 after trastuzumab and pertuzumab between March 1, 2013, and July 15, 2015, via electronic pharmacy records and departmental databases at three institutions: MD Anderson Cancer Center, Smilow Cancer Hospital at Yale, and The James Cancer Hospital at the Ohio State University. We reviewed medical records of each case to confirm treatment sequencing and outcome. Results Of patients, 82 were identified and 78 were available for outcome analysis; 32% received T-DM1 as first- and second-line line therapy, and 48% received it as fourth-line treatment or later. Rate of prolonged duration on therapy, defined as duration on therapy ≥ 6 months, was 30.8% (95% CI, 20.6% to 41.1%), and tumor response rate was 17.9% (95% CI, 9.4% to 26.4%). Median duration on therapy was 4.0 months (95% CI, 2.7 to 5.1; range, 0 to 22.5 months). T-DM1 was discontinued for disease progression in 84% of patients and for toxicity in 10%. Conclusion Tumor response rates were lower than in prior reports of trastuzumab-resistant, HER2-positive MBC, but one third of patients received therapy with T-DM1 for ≥ 6 months, which suggests a clinically relevant benefit in patients who received prior pertuzumab.

Mammographic breast density is associated with the development of contralateral breast cancer

Women with dense mammographic breast density (BD) have a 2‐fold increased risk of developing primary breast cancer (BC). The authors hypothesized that dense mammographic BD also is associated with an increased risk of developing contralateral breast cancer (CBC).

Nomogram to predict pathologic complete response in HER2-positive breast cancer treated with neoadjuvant systemic therapy.

Background:Pathologic complete response (pCR) is associated with improved survival outcomes in patients with HER2-positive primary breast cancer. We developed a nomogram to predict the probability of pCR rates by using oestrogen receptor (ER) expression, progesterone receptor (PR) expression and HER2/CEP17 ratio as continuous variables.Methods:We retrospectively reviewed patients with stages I–III HER2-positive invasive breast cancer who had definitive surgery in 1999–2015 and received neoadjuvant systemic therapy (NST). Multivariate logistic regression models were applied to assess the effect of variables on pCR. A nomogram was built to estimate the probability of pCR. The discriminative ability was estimated by the concordance index (C-index). The accuracy was assessed graphically with a calibration curve.Results:A total of 793 patients were included in the analysis. Low ER expression (P<0.001), high HER2/CEP12 ratio (P=0.03), and non-inflammatory breast cancer subtype (P=0.003) were associated with increased pCR rates. Regimens containing trastuzumab or trastuzumab and pertuzumab were associated with higher pCR rates than cytotoxic agents alone (P<0.001 and P<0.001, respectively). The C-index was 0.69. The calibration curve showed good agreement.Conclusions:Our nomogram predicted the pCR rate after NST among patients with HER2-positive primary breast cancer using clinicopathologic factors.

Long‐Term Survival of De Novo Stage IV Human Epidermal Growth Receptor 2 (HER2) Positive Breast Cancers Treated with HER2‐Targeted Therapy

BACKGROUND An increasing proportion of human epidermal growth receptor 2 (HER2) positive (HER2+) metastatic breast cancer (MBC) is diagnosed as de novo stage IV disease. We hypothesize that a subset of these patients who achieve no evidence of disease (NED) status after multimodality HER2-targeted treatments may have prolonged progression-free survival (PFS) and overall survival (OS). MATERIALS AND METHODS Patients with de novo stage IV, HER2+ MBC (n = 483) diagnosed between 1998 and 2015 were identified at two institutions (Yale and MD Anderson Cancer Centers). Clinical variables, treatment details, and survival outcomes were compared between those who achieved NED and those who did not. RESULTS All patients received trastuzumab, and 20% also received pertuzumab as first-line therapy. The median OS was 5.5 years (95% confidence interval [Cl]: 4.8-6.2). Sixty-three patients (13.0%) achieved NED; their PFS and OS rates were 100% and 98% (95% CI: 94.6%-100%), respectively, at 5 years and remained the same at 10 years. For patients with no NED (n = 420), the PFS and OS rates were 12% (95% CI: 4.5%-30.4%) and 45% (95% CI: 38.4%-52.0%) at 5 years and 0% and 4% (95% CI, 1.3%-13.2%) at 10 years, respectively. NED patients more frequently had solitary metastasis (79% vs. 51%, p = .005) and surgery to resect cancer (59% vs. 22%, p ≤ .001). In multivariate analysis, NED status (hazard ratio [HR]: 0.014, p = .0002) and estrogen receptor positive status (HR: 0.72; p = .04) were associated with prolonged OS. CONCLUSION Among patients with de novo stage IV, HER2+ MBC, those who achieve NED status have a very high PFS and OS. Further randomized studies are required to fully understand the impact of systemic or locoregional therapy on achieving these excellent long-term outcomes. IMPLICATIONS FOR PRACTICE In this retrospective review at two institutions, it was demonstrated that 13% of patients with de novo stage IV, human epidermal growth receptor 2 positive metastatic breast cancer achieved no evidence of disease (NED) status with trastuzumab-based therapy plus/minus local therapies, and these patients had a very high progression-free survival (100%) and overall survival (98%) at both the 5- and 10-year time points. Achieving NED status may be an important therapeutic goal. However, further randomized studies are required to fully understand the impact of systemic or locoregional therapy on achieving these excellent long-term outcomes.

Determinants of Weight Gain During Adjuvant Endocrine Therapy and Association of Such Weight Gain With Recurrence in Long-term Breast Cancer Survivors

Micro‐Abstract We conducted a retrospective study of breast cancer survivors to determine the risk factors for weight gain during endocrine therapy and the association of such weight gain with recurrence. Background: Weight gain is a negative prognostic factor in breast cancer (BC) patients. The risk factors for weight gain during adjuvant endocrine therapy (ET) and the extent to which such weight gain is associated with disease recurrence remain unclear. Patients and Methods: We retrospectively identified a cohort of women with a diagnosis of stage I‐III, hormone receptor–positive, human epidermal growth factor receptor 2‐negative BC from January 1997 to August 2008, who had received initial treatment at the MD Anderson Cancer Center, had completed 5 years of ET, and had remained free of locoregional or distant relapse or contralateral BC for ≥ 5 years after diagnosis. The weight change at the end of 5 years of ET was measured as the percentage of the change in weight from the start of ET, with a weight gain of > 5% considered clinically significant. Multivariable logistic regression and Cox proportional hazards models were used to assess the determinants of such weight gain and the risk of recurrence after 5 years. Results: Of 1282 long‐term BC survivors, 432 (33.7%) had a weight gain of > 5% after 5 years of ET. Women who were premenopausal at diagnosis were 1.40 times more likely than women who were postmenopausal at diagnosis to have a weight gain of > 5%. Asian women had the lowest risk of gaining weight. The recurrence risks of patients who had gained weight and those who had not were not significantly different. Conclusion: Premenopausal BC patients had an increased risk of weight gain after 5 years of ET; however, BC patients with a weight gain of > 5% did not have an increased risk of disease recurrence.

How Does MR Imaging Help Care for the Breast Cancer Patient? Perspective of a Medical Oncologist

Although traditional assessment with clinical examination, mammogram, and ultrasound is generally accepted for detection and staging of breast cancer, MR imaging is commonly used to detect occult cancers in the breast and regional nodes in the early stage and to determine the extent of disease in patients with metastatic disease. Several studies have shown a variety of uses for MR imaging in the staging of breast cancer and assessment of treatment response in the neoadjuvant (preoperative) setting. This article reviews the impact of MR imaging in different settings on medical oncology decision-making in patients with breast cancer.

Genetic Counseling Referral Rates in Long-Term Survivors of Triple-Negative Breast Cancer

Background: Inherited BRCA gene mutations (pathogenic variants) cause 10% of breast cancers. BRCA pathogenic variants predispose carriers to triple-negative breast cancer (TNBC); around 30% of patients with TNBC carry BRCA pathogenic variants. The 2018 NCCN Guidelines for Genetic/Familial High-Risk Assessment: Breast and Ovarian recommend genetic counseling referrals for patients with TNBC diagnosed at age ≤60 years. This study sought to describe genetic counseling referral patterns among long-term TNBC survivors at The University of Texas MD Anderson Cancer Center. Methods: This single-institution retrospective analysis of female long-term (disease-free for ≥5 years) TNBC survivors sought to determine the rate of genetic counseling referral among patients diagnosed at age ≤60 years between 1992 and 2008. Patients who underwent treatment and surveillance visits at our institution and were followed until 2017 were included. We collected BRCA pathogenic variant status among tested patients. Descriptive statistical methods and a univariate analysis were used to identify patient characteristics associated with genetic counseling referral. Results: We identified 646 female long-term TNBC survivors with a median age at diagnosis of 47 years. Of these, 245 (38%) received a recommendation for a genetic counseling referral. Among those referred, 156 (64%) underwent genetic testing, and 35% of those tested had BRCA pathogenic variants. Interestingly, among those referred, 20% declined genetic testing. The rate of genetic referrals improved over time, from 25% among TNBC survivors whose last surveillance visit was between 2011 and 2013 to 100% among those whose last surveillance visit was between 2014 or later. Younger age and premenopausal status at diagnosis and a family history of breast or ovarian cancer were associated with an increased rate of referral for genetic counseling. Conclusions: Among long-term TNBC survivors, the rate of referral to genetic counseling increased over time, and among those tested, 35% carried a BRCA pathogenic variant. Survivorship care provides an excellent opportunity to refer eligible patients for genetic counseling.

Neoadjuvant Pertuzumab-containing Regimens Improve Pathologic Complete Response Rates in Stage II to III HER-2/neu-positive Breast Cancer: A Retrospective, Single Institution Experience

Introduction: Several human epidermal growth factor 2 (HER2)‐targeted regimens are used to treat HER2‐positive (HER2+) breast cancer (BC). The goal of this study was to retrospectively determine the pathologic complete response (pCR) rate for trastuzumab and pertuzumab (HP)‐containing regimens compared with trastuzumab (H)‐containing regimens for stage II to III HER2+ BC. Patients and Methods: Patients (n = 977) with stage II to III HER2+ BC who received neoadjuvant HER2‐targeted therapy from 2005 to 2016 and underwent definitive breast and axillary lymph node surgery were identified. pCR was defined as ypT0/is, ypN0. Univariate/multivariate logistic regression and the χ2 test for comparing proportions was used for the statistical analysis. Results: The pCR rate was higher for the HP group (n = 170) compared with the H group (n = 807): 59% versus 46% (odds ratio, 1.7; 95% confidence interval, 1.21‐2.37; P = .0021). After adjustment for clinically important factors (age, date of diagnosis, stage, tumor grade, nodal status, hormone receptor [HR] status, menopausal status, and chemotherapy backbone) the adjusted odds ratio was 2.25 (95% confidence interval, 1.08‐4.73; P = .032). In multivariate analysis, a significant predictor of pCR in both groups included HR status (HR‐negative > HR‐positive). Conclusion: These results demonstrate that HP‐containing regimens yield higher pCR rates compared with H‐containing regimens in patients with stage II to III HER2+ BC in clinical practice regardless of chemotherapy backbone.

Abstract 2338: CDK4/6 and autophagy inhibitors synergize to induce senescence in cancers with an intact G1/S checkpoint

Deregulation of the cell cycle machinery is a hallmark of most cancers. The crucial role of the CDK4/6-CyclinD pathway in tumorigenesis has led to the successful development and FDA approval (palbociclib) of CDK4/6 inhibitors for the treatment of advanced estrogen receptor positive breast cancer. However, two major clinical challenges remain: i) lack of a reliable biomarker to predict treatment response and ii) adverse events leading to interruption or discontinuation of treatment which possibly thus curtailing therapeutic benefit. We found that treatment of ER+ breast cancer cell lines with the CDK4/6 inhibitor palbociclib resulted in a dose-dependent sustained growth inhibition and senescence. Interestingly, breast cancer cells activate autophagy in response to palbociclib, a stress response process that promotes cancer cell survival. Genetic ablation of crucial autophagic genes or pharmacological inhibition of autophagy increases the sensitivity of ER+ breast cancer cells to palbociclib and the other CDK4/6 inhibitors, ribociclib and abemaciclib. This was confirmed in vivo, where the combination of palbociclib and autophagy inhibitor, hydroxychloroquine (HCQ) resulted in a significantly improved and a sustained tumor shrinkage. To identify biomarkers that predict response to CDK4/6 inhibition, we examined the G1 checkpoint proteins and found that knockdown of Rb or overexpression of the oncogenic low molecular weight isoforms of Cyclin-E (LMW-E) mediates resistance to palbociclib and its combination with autophagy inhibitor. More significantly, immunohistochemically staining of pre-treatment biopsies from palbociclib treated patients strengthened the correlation between palbociclib efficacy and an intact G1/S checkpoint (Rb+ve /LMWE-ve), resulting in a significantly longer progression free survival compared to the other patient groups; thus solidifying Rb and LMW-E as reliable prognostic biomarkers for palbociclib treatment. Finally, we examined the biomarker driven synergy between CDK4/6 and autophagy inhibition in several other cancer cell lines. Several solid tumors (ovarian, lung, pancreatic, colon, prostate) and triple negative breast cancer (TNBC) cell lines exhibited a synergistic response to palbociclib/HCQ combination treatment dependent upon an intact G1/S transition (Rb+/LMWE-). This was also verified in a TNBC patient derived xenograft (PDX) model. Thus, this study addresses the aforementioned limitations and provides a novel and promising biomarker-driven combination therapeutic strategy to treat breast and other solid tumors. We predict that this combination of CDK4/6 and autophagy inhibitors would be more beneficial than standard dose palbociclib in patients, allowing us to lower the dose, minimize palbociclib mediated toxicities and potentially improve overall patient survival - a goal that has not yet been met with currently approved treatment combinations. Citation Format: Smruthi Vijayaraghavan, Cansu Karakas, Xian Chen, Iman Doostan, Akshara S. Raghavendra, Min Yi, Ravi Amaravadi, Kelly Hunt, Debu Tripathy, Khandan Keyomarsi. CDK4/6 and autophagy inhibitors synergize to induce senescence in cancers with an intact G1/S checkpoint [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2338. doi:10.1158/1538-7445.AM2017-2338