Cesar Augusto Santa-Maria

Changing Treatment Paradigms in Metastatic Breast Cancer: Lessons Learned

Advances in understanding tumor biology, particularly signaling pathways, have led to the development and approval of many novel agents and have changed the landscape of therapy for patients with metastatic breast cancer. This review highlights some of the recent successes and failures in breast cancer drug development, including strategies to overcome endocrine and human epidermal growth factor 2-neu (HER2) resistance, targeting triple-negative breast cancers (which do not express the HER2, estrogen, and progesterone receptors) through novel receptors, harnessing the immune system, and new ways of targeting angiogenesis. For patients with metastatic breast cancer, expanding therapeutic options through clinical trial participation is a crucial part of modern oncology practice. As we continue to learn how to use targeted therapies in the context of genomic medicine, analysis of the tumor in real-time may become increasingly important, giving researchers the information needed to start combining therapies in a biologically informed manner.

Targeting Epidermal Growth Factor Receptor in triple negative breast cancer: New discoveries and practical insights for drug development

Triple negative breast cancer (TNBC) accounts for 10-20% of cases in breast cancer. Despite recent advances in the treatment of hormonal receptor+ and HER2+ breast cancers, there are no targeted therapies available for TNBC. Evidence supports that most patients with TNBC express the transmembrane Epidermal Growth Factor Receptor (EGFR). However, early phase clinical trials failed to demonstrate significant activity of EGFR-targeted monoclonal antibodies and/or tyrosine kinase inhibitors. Here, we review the recent discoveries related to the underlying biology of the EGFR pathway in TNBC, clinical progress to date and suggest rational future approaches for investigational therapies in TNBC.

Genomic landscape of DNA repair genes in cancer

DNA repair genes are frequently mutated in cancer, yet limited data exist regarding the overall genomic landscape and functional implications of these alterations in their entirety. We created comprehensive lists of DNA repair genes and indirect caretakers. Mutation, copy number variation (CNV), and expression frequencies of these genes were analyzed in COSMIC. Mutation co-occurrence, clinical outcomes, and mutation burden were analyzed in TCGA. We report the 20 genes most frequently with mutations (n > 19,689 tumor samples for each gene), CNVs (n > 1,556), or up- or down-regulated (n = 7,998). Mutual exclusivity was observed as no genes displayed both high CNV gain and loss or high up- and down-regulation, and CNV gain and loss positively correlated with up- and down-regulation, respectively. Co-occurrence of mutations differed between cancers, and mutations in many DNA repair genes were associated with higher total mutation burden. Mutation and CNV frequencies offer insights into which genes may play tumor suppressive or oncogenic roles, such as NEIL2 and RRM2B, respectively. Mutual exclusivities within CNV and expression frequencies, and correlations between CNV and expression, support the functionality of these genomic alterations. This study provides comprehensive lists of candidate genes as potential biomarkers for genomic instability, novel therapeutic targets, or predictors of immunotherapy efficacy.

Concordance of Genomic Alterations by Next-Generation Sequencing in Tumor Tissue versus Circulating Tumor DNA in Breast Cancer

While identifying genomic alterations in tumor tissue is the current gold-standard technique for molecular profiling, circulating tumor DNA (ctDNA) represents a noninvasive method of assessing genomic alterations using peripheral blood. The concordance of genomic alterations between two commercially available ctDNA and tissue biopsies was compared in 45 patients with breast cancer using paired next-generation sequencing tissue and ctDNA biopsies. Across all genes, concordance between the two platforms was 91.0% to 94.2%. When only considering genomic alterations in either assay (e.g., excluding wild type/wild type genes), concordance was 10.8% to 15.1% with full plus partial concordance of 13.8% to 19.3%. Concordant mutations were associated with significantly higher variant allele frequency. Over half of mutations detected in either technique were not detected using the other biopsy technique. Including variants of unknown significance, the average number of alterations per patient was significantly higher for tissue (4.56) compared with ctDNA (2.16). When eliminating alterations not detectable in the ctDNA assay, mean number of alterations for tissue and ctDNA was similar (2.67 for tissue, 2.16 for ctDNA). Across five representative genes (TP53, PIK3CA, ERBB2, BRCA1, and BRCA2), sensitivity and specificity were 35.7% and 95.0%, respectively. Concordance when genomic alterations was detected in either tissue or ctDNA was low with each technique detecting a significant amount of nonoverlapping mutations. Potential explanations for the lack of concordance include tumor heterogeneity, different sequencing techniques, spatial and temporal factors, and potential germline DNA contamination. The study indicates that both tissue and blood-based NGS may be necessary to describe the complex biology of breast cancer. Mol Cancer Ther; 16(7); 1412–20. ©2017 AACR.

Developmental therapeutics for patients with breast cancer and central nervous system metastasis: current landscape and future perspectives

Breast cancer is the second-leading cause of metastatic disease in the central nervous system (CNS). Recent advances in the biological understanding of breast cancer have facilitated an unprecedented increase of survival in a subset of patients presenting with metastatic breast cancer. Patients with HER2 positive (HER2+) or triple negative breast cancer are at highest risk of developing CNS metastasis, and typically experience a poor prognosis despite treatment with local and systemic therapies. Among the obstacles ahead in the realm of developmental therapeutics for breast cancer CNS metastasis is the improvement of our knowledge on its biological nuances and on the interaction of the blood–brain barrier with new compounds. This article reviews recent discoveries related to the underlying biology of breast cancer brain metastases, clinical progress to date and suggests rational approaches for investigational therapies.

Breast cancer and immunology: biomarker and therapeutic developments

While breast cancer has not historically been considered an immunogenic cancer, recent data demonstrating the powerful anti-cancer effects of immune checkpoints in many cancers, including breast cancer, has reinvigorated the field. Although the responses are generally low with single agents, some patients experience disease control for a long period of time. Selecting appropriate patients for immunotherapy is an important area of research, and many biomarkers are under investigation. Although immunotherapies are still in their early stages of development, learning how to use them in combination with other agents that can alter antigen presentation or other immune elements will be crucial. This review aims to summarize efforts in immune-related biomarker and drug development, particularly as it pertains to breast cancer.

Developmental therapeutics for inflammatory breast cancer: Biology and translational directions.

Inflammatory breast cancer (IBC) is a rare and aggressive form of breast cancer, which accounts for approximately 3% of cases of breast malignancies. Diagnosis relies largely on its clinical presentation, and despite a characteristic phenotype, underlying molecular mechanisms are poorly understood. Unique clinical presentation indicates that IBC is a distinct clinical and biological entity when compared to non-IBC. Biological understanding of non-IBC has been extrapolated into IBC and targeted therapies for HER2 positive (HER2+) and hormonal receptor positive non-IBC led to improved patient outcomes in the recent years. This manuscript reviews recent discoveries related to the underlying biology of IBC, clinical progress to date and suggests rational approaches for investigational therapies.

Abstract P6-13-11: Phase I study of alpelisib and T-DM1 in trastuzumab-refractory HER2-positive metastatic breast cancer

BACKGROUND: Constitutive activation of the phosphatidylinositol-3-kinase (PI3K) signaling pathway is a mechanism of trastuzumab resistance in HER2-positive metastatic breast cancer (MBC). Alpelisib (BYL-719) is the first oral PI3K inhibitor that selectively inhibits the PI3K alpha isoform. We aimed to determine the maximum tolerated dose (MTD), safety, and activity of alpelisib in combination with ado-trastuzumab emtansine (T-DM1) in HER2-positive MBC that has progressed on or after trastuzumab and/or taxane-based regimens. METHODS: This phase I study enrolled patients with HER2-positive MBC who received alpelisib daily (cohort 1: 300 mg, cohort (-)1: 250 mg) and T-DM1 3.6 mg/m2 on Day 1 of a 3 week cycle using a 3+3 design with dose expansion at the MTD. Treatment was continued until progression, unacceptable toxicity, or patient preference. Blood was collected for pharmacokinetic (PK) and pharmacodynamic (PD) markers. Dose-limiting toxicity (DLT) was defined as CTCAE Grade 3 or 4 adverse events (AE) during the first cycle. Imaging and echocardiogram were obtained every 3 cycles. RESULTS: Dose escalation is completed and included in this analysis (N=8). Median age was 53 (range 46-79) with median ECOG Performance Status of 1. Median prior lines of therapy in the metastatic setting was 6 (range 0-12) including 5 patients who progressed on prior T-DM1 (after median 6 cycles). Two patients had de novo MBC and 3 with ER and/or PR positive disease. Median number of metastatic sites was 2 (range 1-5) including brain (inactive), liver, and lung. Median number of cycles of alpelisib and T-DM1 per patient was 5.5 (range 1-12). Five patients were enrolled in cohort 1 with 2 DLTs (both grade 3 rash), leading to cohort (-)1, in which there were no DLTs. The most common treatment-related AEs were fatigue (n=7, 86%), nausea (n=6, 75%), aspartate aminotransferase increase (n=4, 50%), and thrombocytopenia (n=4, 50%). Grade 3 AEs were rash (n = 3), hyperglycemia (n=1), hypertension (n=1) and thrombocytopenia (n=1), which occurred in only cohort 1. Grade 3 rash typically occurred during cycle 1, which resolved with temporary interruption and subsequent dose reduction of alpelisib and the use of topical steroids for median 9.3 days (range 6-12). Grade 3 hyperglycemia was reversible with oral anti-diabetic treatment. A total of 4 dose reductions occurred in cohort 1. No Grade 3/4 AEs or dose reductions occurred in cohort -1. In total, only 0.07% of all AEs were Grade 3 and none Grade 4. The MTD for alpelisib was established as 250 mg daily. In 7 evaluable patients, there were 6 objective responses after 3 cycles, a response rate of 86% (1 confirmed complete response, 2 confirmed partial response [PR], and 3 unconfirmed PR). Five (67%) of these patients continue to have durable responses (median 6.5 cycles) at doses 200-250 mg daily. One patient had progression of disease. PK/PD results and PIK3CA mutation testing are pending. CONCLUSION: The combination of alpelisib and T-DM1 appears to be safe, well tolerated, with clinical activity in HER2-positive MBC patients including those who progressed on prior T-DM1 therapy. The study is currently in dose expansion with goal of enrolling 10 additional patients with T-DM1 and alpelisib 250 mg daily. Citation Format: Jain S, Nye L, Santa-Maria C, Bontemps L, Williams A, Garrett H, Dammrich E, Giles F, Gradishar W. Phase I study of alpelisib and T-DM1 in trastuzumab-refractory HER2-positive metastatic 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 P6-13-11.

Synchronous breast cancer and alveolar rhabdomyosarcoma bone marrow metastases

Alveolar rhabdomyosarcoma (RMS) is primarily a malignancy of childhood and adolescence. While RMS is rare in adults, the breast and the bone marrow are known but uncommon sites for metastatic disease. Bone marrow is also a known sanctuary site for metastatic breast cancer. We present the case of a woman with a remote history of breast cancer and RMS who developed anemia and thrombocytopenia of unknown etiology. Additional laboratory tests were negative for a cause; therefore, the decision was made to proceed with a bone marrow biopsy. The initial biopsy results were consistent with breast cancer metastasis. Subsequent diagnostic imaging of the breast led to biopsy of an enlarging morphologically benign breast mass, unexpectedly yielding alveolar RMS. This unanticipated diagnosis led to revaluation of the bone marrow, this time showing synchronous metastases from breast carcinoma and alveolar RMS. Imaging findings of this patient, along with literature review of RMS imaging characteristics, will be reviewed.

Abstract 2636: Targeted therapies to ERBB receptors downregulate expression of PD-L1: implications in combination therapies

Background: Inflammatory breast cancer (IBC) is the most aggressive and lethal form of primary breast cancer. Inflammatory signaling pathways are active in IBC, but the function of the immune response remains elusive. ErbB receptors play a role in IBC. ERBB2 is amplified in 50% of IBCs, and ERBB3 is also mutated in IBC. Currently, Lapatinib, a dual ErbB inhibitor, is used in IBC patients with ERBB2 amplification. Although immune cell inflammatory signaling may promote IBC tumor growth and metastasis, the presence of cytotoxic tumor-associated lymphocytes has also been associated with a more favorable breast cancer prognosis. The contradictory nature of the immune data highlights the need to elucidate the relationship between the immune response and subsequent treatments. Given the active IBC immune component and the recent clinical benefit of immune checkpoint inhibitors in cancer treatment, IBC’s may represent a clinically unique breast cancer population that may benefit from immunomodulating agents. Interestingly, Myc is a downstream effector of ErbB signaling, and Myc is thought to regulate the expression of immune checkpoint proteins CD47 and PD-L1. The presence of PD-L1-positive IBC immune infiltrate suggests that IBC’s may benefit from therapies that disrupt PD-L1 signaling together with ErbB inhibitors. METHODS: IHC was used to examine immune checkpoint signaling and characterize the tumor-immune infiltrate. Tumor tissues were also characterized using an RNA-seq panel that examined the expression of 377 immune-related genes. Cell lines (BT474, SKR3, AU565, and SUM225) were treated with Lapatinib and Neratinib to examine the relationship between growth factor receptors and downstream immune signaling pathways. RESULTS: RNA-seq revealed the expression of specific immunosuppressive signaling pathways in tumors. Treatment of breast cancer cells with ErbB inhibitors resulted in a decrease in the levels of PD-L1. Treatment with Lapatinib and Neratinib diminished PD-L1 in all cell lines. Levels of Phospho-Stat3 decreased in BT474 and Sum225 but not in SKBR3 and AU565, implying that PD-L1 is regulated by another mechanism (ERK-MYC). CONCLUSION: Our results provide mechanistic insight into ErbB receptor activation and the expression of downstream signaling molecules (Stat3, Myc, PD-L1, and others). In addition, our unique RNA-seq immune signature reveals the expression of several genes that may serve as biomarkers of inhibitory immune signaling pathways. Our laboratory is currently examining the correlation between PD-L1 expression and the activation of ErbB2 in model systems and clinical trials using ErbB inhibitors in combination with PD-L1 inhibitors. Our immune panel gene signature may serve as a useful diagnostic test that, in conjunction with traditional ErbB testing, can identify patients that will benefit from combination therapy of an ErbB inhibitor and an immune checkpoint inhibitor. Note: This abstract was not presented at the meeting. Citation Format: Christopher A. Hamm, Sumin Zhao, Cesar A. Santa-Maria, Massimo Cristofanilli, Neil L. Spector, Sarah Bacus. Targeted therapies to ERBB receptors downregulate expression of PD-L1: implications in combination therapies [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 2636. doi:10.1158/1538-7445.AM2017-2636