Therapeutic landscape of metaplastic breast cancer

Metaplastic breast carcinomas (MPBC) are rare, aggressive and relatively chemorefractory tumors with a high unmet need. While most are "triple negative" and lack expression of estrogen, progesterone and HER2 receptors, MPBC are associated with worse outcomes compared to conventional triple negative invasive tumors. MPBCs are genetically heterogeneous and harbor somatic mutations, most frequently in TP53, PIK3CA and PTEN, with emerging studies suggesting a role for novel targeted therapies. These tumors have also been associated with overexpression of PD-L1 and tumor-infiltrating lymphocytes suggesting an endogenous immune response and therefore a rationale for treatment with immunotherapies. Here, we focus on therapeutic options for this difficult to treat breast cancer subtype and encourage physicians to consider targeted therapies/immunotherapies as part of ongoing clinical trials.

Abstract ES9-2: Updates on immunotherapy for TNBC

Immunotherapeutic strategies have revolutionized the treatment of cancer. Immune checkpoint blockade (ICB) agents such as inhibitors of programmed cell death receptor-1 (PD-1) and programmed cell death ligand-1 (PD-L1) have been FDA-approved for the treatment of various tumors.

While breast cancers have previously been considered immunologically quiescent compared with other tumor types, recent investigations underscore the immunogenicity of some breast tumors. Triple negative breast cancers (TNBCs) in particular, have the highest rates of tumor-infiltrating lymphocytes (TILs) compared with other subtypes at diagnosis. TILs are indicative of a pre-existing anti-tumor immune response which carries a better prognosis in patients with early TNBC, at least in part due to a better response to conventional cancer therapies. It has been demonstrated that TILs correlate with pathologic complete response (pCR) after neoadjuvant chemotherapy (Denkert et al, Lancet Oncol 2018). The survival benefit associated with TIL in early TNBC is remarkable with a 10% increase in TIL correlating with a 19% reduction in risk of death in trials of adjuvant chemotherapy (Adams et al, J Clin Oncol 2014). These advances ignited the studies of ICB in TNBC with the goal to harness the anti-tumor immune response to improve patient outcomes.

Initial Phase I/II trials in metastatic TNBC showed proof of principle that durable responses could be achieved with ICB monotherapy, but also highlighted the need to develop rational combinations. ICB agents address one important step by which the T-cell response can be blunted, counteracting PD-L1 expressed in the tumor microenvironment in an effort to avoid immune destruction. However, as depicted in the Cancer Immunity Cycle, which manages the delicate balance between the recognition of nonself and the prevention of autoimmunity (Chen et al, Immunity 2013), there are multiple steps required for an effective immune response. Released tumor antigens must be presented in the context of major histocompatibility complexes (MHC) on activated antigen presenting cells to prime an efficient T cell response. Activated T cells must then traffic to the tumor site, infiltrate into the tumor, recognize, and kill tumor cells. Different therapeutic strategies including chemotherapy and radiotherapy are currently being studied as combination partners due to their potential of inducing an immunogenic cell death (Galluzzi et al, Nat Rev Immunol 2017).

Recently the first positive phase 3 chemo-immunotherapy study was reported in metastatic TNBC (Schmid et al, ESMO 2018). Impassion130, a global, randomized, double-blind trial of nab-paclitaxel with or without atezolizumab in front-line metastatic TNBC, met its co-primary progression-free survival (PFS) endpoint in the intent-to-treat as well as the PD-L1+ population, with clinically meaningful overall survival (OS) benefit seen at interim OS analysis in PD-L1+ patients. Additional phase 3 trials of ICB in TNBC are ongoing in the adjuvant, neoadjuvant and metastatic setting.

Citation Format: Adams S. Updates on immunotherapy for TNBC [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr ES9-2.

    

Abstract P6-18-31: PROCLAIM-CX-072: Monotherapy for advanced triple negative breast cancer with skin metastases in a phase 1-2 trial of the PD-L1 probody therapeutic CX-072

Background: Probody™ therapeutics are novel, fully recombinant antibody prodrugs designed to remain relatively inactive in healthy tissue and to be specifically activated by proteases in the tumor microenvironment. In this way, Probody therapeutics may broaden the therapeutic window for effective but potentially toxic anticancer agents. CX-072 is a Probody therapeutic directed against programmed death-ligand 1 (PD-L1) for the treatment of cancer patients. In a first-in-human, open-label, multicenter, dose-escalation, 3+3 design, phase 1-2 study, PROCLAIM-CX-072 (PRObody CLinical Assessment In Man) (NCT03013491), 22 patients were enrolled in the phase 1 dose escalation portion. Twenty patients were evaluable per RECIST v1.1. Three patients had confirmed partial response (15%), including a 39-year-old woman with stage IV triple negative breast cancer (TNBC) treated with 10 mg/kg CX-072 monotherapy whose disease had progressed on one previous line of chemotherapy for metastatic disease. Metastatic sites included extensive nodal disease and skin/chest wall lesions. The tumor was negative for PD-L1 expression, was microsatellite stable, and had a low tumor mutational burden (4 mutations/megabase). Positive results from the phase 1 study suggest that additional exploration of treatment with CX-072 monotherapy in the TNBC patient population is warranted.

Dose expansion trial design: The phase 2 dose expansion part of the PROCLAIM-CX-072 study will include enrollment of TNBC patients with skin metastases. Key inclusion criteria for patients in the TNBC cohort are as follows: naive to immunotherapy (PD-1/PD-L1 and CTLA-4 inhibitors), approved immune checkpoint inhibitor agents not available, histologically confirmed triple negative (estrogen receptor–, progesterone receptor–, and human epidermal growth factor receptor-2–negative cancer per ASCO-CAP guidelines), previously treated with 1 to 3 systemic chemotherapy regimens, and locally advanced and recurrent skin or subcutaneous metastases not suitable for surgical resection or radiotherapy. Patients will receive doses of 10 mg/kg CX-072 intravenously every 2 weeks. Efficacy will be evaluated using RECIST v1.1 and immune-related RECIST criteria. Safety and tolerability will be assessed based on the incidence and severity of adverse events (categorized by NCI CTCAE criteria, v4.03) and relationship to study drug. Other analyses will include pharmacokinetics, incidence of anti-drug antibodies against CX-072, exploratory analysis for immune response, and CX-072 activation in the tumor.

PROBODY is a trademark of CytomX Therapeutics, Inc.

Citation Format: Adams S, Hamilton E, Ott PA, Cho D, Kalinsky K, LoRusso P, Will M, Huels V, Benson B, Murias C, Arkenau H-T. PROCLAIM-CX-072: Monotherapy for advanced triple negative breast cancer with skin metastases in a phase 1-2 trial of the PD-L1 probody therapeutic CX-072 [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P6-18-31.

Prognostic implications of residual disease tumor-infiltrating lymphocytes and residual cancer burden in triple-negative breast cancer patients after neoadjuvant chemotherapy

BACKGROUND

For primary triple-negative breast cancer (TNBC) treated with neoadjuvant chemotherapy (NAC), higher pretreatment tumor-infiltrating lymphocytes (TILs) correlates with increased pathologic complete response (pCR) rates, and improved survival. We evaluated the added prognostic value of residual disease (RD) TILs to residual cancer burden (RCB) in predicting survival post-NAC.

PATIENTS AND METHODS

We combined four TNBC NAC patient cohorts who did not achieve pCR. RD TILs were investigated for associations with recurrence-free survival (RFS), and overall survival (OS) using Cox models with stromal TILs as a continuous variable (per 10% increment). The likelihood ratio test was used to evaluate added prognostic value of RD TILs.

RESULTS

A total of 375 RD TNBC samples were evaluable for TILs and RCB. The median age was 50 years, with 62% receiving anthracycline/taxane chemotherapy. The RCB class after NAC was 11%, 50%, and 39% for I, II, and III, respectively. The median RD TIL level was 20% (IQR 10-40). There was a positive correlation between RD TIL levels and CD8+ T-cell density (ρ = 0.41). TIL levels were significantly lower with increasing post-NAC tumor (P = 0.005), nodal stage (P = 0.032), but did not differ by RCB class (P = 0.84). Higher RD TILs were significantly associated with improved RFS (HR: 0.86; 95% CI 0.79-0.92; P < 0.001), and improved OS (HR: 0.87; 95% CI 0.80-0.94; P < 0.001), and remained significant predictors in multivariate analysis (RFS P = 0.032; OS P = 0.038 for OS). RD TILs added significant prognostic value to multivariate models including RCB class (P < 0.001 for RFS; P = 0.021 for OS). The positive prognostic effect of RD TILs significantly differed by RCB class for RFS (PInt=0.003) and OS (PInt=0.008) with a greater magnitude of positive effect observed for RCB class II than class III.

CONCLUSIONS

TIL levels in TNBC RD are significantly associated with improved RFS and OS and add further prognostic information to RCB class, particularly in RCB class II.

Computational analysis and identification of battery materials

Crystallography is a powerful descriptor of the atomic structure of solid-state matter and can be applied to analyse the phenomena present in functional materials. Especially for ion diffusion – one of the main processes found in electrochemical energy storage materials – crystallography can describe and evaluate the elementary steps for the hopping of mobile species from one crystallographic site to another. By translating this knowledge into parameters and search for similar numbers in other materials, promising compounds for future energy storage materials can be identified. Large crystal structure databases like the ICSD, CSD, and PCD have accumulated millions of measured crystal structures and thus represent valuable sources for future data mining and big-data approaches. In this work we want to present, on the one hand, crystallographic approaches based on geometric and crystal-chemical descriptors that can be easily applied to very large databases. On the other hand, we want to show methodologies based onab initioand electronic modelling which can simulate the structure features more realistically, incorporating also dynamic processes. Their theoretical background, applicability, and selected examples are presented.

Weaning practices in phenylketonuria vary between health professionals in Europe

Background

In phenylketonuria (PKU), weaning is considered more challenging when compared to feeding healthy infants. The primary aim of weaning is to gradually replace natural protein from breast milk or standard infant formula with solids containing equivalent phenylalanine (Phe). In addition, a Phe-free second stage L-amino acid supplement is usually recommended from around 6 months to replace Phe-free infant formula. Our aim was to assess different weaning approaches used by health professionals across Europe.

Methods

A cross sectional questionnaire (survey monkey®) composed of 31 multiple and single choice questions was sent to European colleagues caring for inherited metabolic disorders (IMD). Centres were grouped into geographical regions for analysis.

Results

Weaning started at 17–26 weeks in 85% (n = 81/95) of centres, >26 weeks in 12% (n = 11/95) and < 17 weeks in 3% (n = 3/95). Infant's showing an interest in solid foods, and their age, were important determinant factors influencing weaning commencement. 51% (n = 48/95) of centres introduced Phe containing foods at 17–26 weeks and 48% (n = 46/95) at >26 weeks. First solids were mainly low Phe vegetables (59%, n = 56/95) and fruit (34%, n = 32/95).

A Phe exchange system to allocate dietary Phe was used by 52% (n = 49/95) of centres predominantly from Northern and Southern Europe and 48% (n = 46/95) calculated most Phe containing food sources (all centres in Eastern Europe and the majority from Germany and Austria). Some centres used a combination of both methods.

A second stage Phe-free L-amino acid supplement containing a higher protein equivalent was introduced by 41% (n = 39/95) of centres at infant age 26–36 weeks (mainly from Germany, Austria, Northern and Eastern Europe) and 37% (n = 35/95) at infant age > 1y mainly from Southern Europe. 53% (n = 50/95) of centres recommended a second stage Phe-free L-amino acid supplement in a spoonable or semi-solid form.

Conclusions

Weaning strategies vary throughout European PKU centres. There is evidence to suggest that different infant weaning strategies may influence longer term adherence to the PKU diet or acceptance of Phe-free L-amino acid supplements; rendering prospective long-term studies important. It is essential to identify an effective weaning strategy that reduces caregiver burden but is associated with acceptable dietary adherence and optimal infant feeding development.

A comparison of methodologies: sibling identification using a relational versus a graph-based approach

IntroductionThe detection of siblings is an important pre-requisite for many research problems, yet is traditionally difficult or time-consuming owing to the way linked data is conventionally stored. We compare the methodology and results for an identification of siblings by SANT DataLink using a legacy relational approach and a graph-based approach. Objectives and ApproachAn existing project involving the identification of sibling clusters using relational techniques was replicated using the same core data in SANT DataLink’s Next Generation Linkage Managment System (NGLMS) which is graph-based. Data is stored in the NGLMS using richer relationships than just 'is W% similar to' or 'is part of group N'. Birth data was separated into children and parents and explicit child/parent relationships recorded. When coupled with electoral roll data using probabilistic and deterministic linkage, sibling structure can be identified by performing network traversal via parents, e.g. crecord—[MOTHER]⟶mrecord—[IS_SIMILAR_TO]⟶mrecord*⟵[MOTHER]—crecord* i.e. find the mother, find that mother’s cluster, find all children related to that cluster. The resulting records are siblings. ResultsA graph-based approach enabled the methology of 'finding siblings' to be more clearly described and communicated by mirroring genealogical structures natively within in the data. Comparable results were achieved in a shorter time with less manual effort using the same underlying data. Generating sibling clusters from the graph-based data required less manual intervention and review as explicit PARENT/CHILD relationships were stored in the data and able to be quickly traversed to assemble familial units and thus siblings. A focus on automated linkage quality rather than manual review was facilitated by the approach. Anomalous structures requiring detailed review, such as multiple fathers and mothers of a single child, were trivially identifiable and so manual effort was focussed on actions where a higher return in terms of end-product quality could be achieved. Conclusion/ImplicationsStoring data in a representation which more closely resembles the the underlying real-world situation allows greater fidelity with respect to data modeling. This in turn, enables the asking of richer questions and makes the answering of such questions much easier.

Early feeding practices in infants with phenylketonuria across Europe

Background

In infants with phenylketonuria (PKU), dietary management is based on lowering and titrating phenylalanine (Phe) intake from breast milk or standard infant formula in combination with a Phe-free infant formula in order to maintain blood Phe levels within target range. Professionals use different methods to feed infants with PKU and our survey aimed to document practices across Europe.

Methods

We sent a cross sectional, survey monkey® questionnaire to European health professionals working in IMD. It contained 31 open and multiple-choice questions. The results were analysed according to different geographical regions.

Results

Ninety-five centres from 21 countries responded. Over 60% of centres commenced diet in infants by age 10 days, with 58% of centres implementing newborn screening by day 3 post birth. At diagnosis, infant hospital admission occurred in 61% of metabolic centres, mainly in Eastern, Western and Southern Europe. Breastfeeding fell sharply following diagnosis with only 30% of women still breast feeding at 6 months.

53% of centres gave pre-measured Phe-free infant formula before each breast feed and 23% alternated breast feeds with Phe-free infant formula. With standard infant formula feeds, measured amounts were followed by Phe-free infant formula to satiety in 37% of centres (n = 35/95), whereas 44% (n = 42/95) advised mixing both formulas together. Weaning commenced between 17 and 26 weeks in 85% centres, ≥26 weeks in 12% and < 17 weeks in 3%.

Discussion

This is the largest European survey completed on PKU infant feeding practices. It is evident that practices varied widely across Europe, and the practicalities of infant feeding in PKU received little focus in the PKU European Guidelines (2017). There are few reports comparing different feeding techniques with blood Phe control, Phe fluctuations and growth. Controlled prospective studies are necessary to assess how different infant feeding practices may influence longer term feeding development.

Scalp as a donor site in children: Is it really the best option?

BACKGROUND

Since 2003 we have used the scalp as a donor site for split skin grafts (SSGs) in major burns when there was a shortage of conventional donor areas. However, we seen a high incidence of complications, contrary to international experience.

OBJECTIVE

The aim of this study was to analyze the results and complications related to the scalp as a donor site and to determine whether there is an association between our specific patient population and the complications encountered.

METHODS

A retrospective review of our scalp donor site outcomes over a 12-year period was conducted. The cohort included 25 patients, 15 of black African descent, nine of mixed race and one Caucasian. The various hair types were identified based on ethnicity and classified into eight types. Most of our patients had hair types VI-VIII. None of these patients had scalp burns and all received standard burn treatment. The SSGs were taken with an electric dermatome with a standard micrometric setting of 0.2mm. Complications were categorized into short- or long-term, with a mean follow-up time of 1.59years.

RESULTS

The mean age of the 25 children was 5.7years. Nineteen sustained flame burns and 6 sustained hot water burns, with a mean total body surface area of 44.9%. A total of 43 scalp procurements were performed in the 25 patients studied. The group of 15 black African patients (hair types VI-VIII) had a total of 22 procurements, the nine patients of mixed race (hair types III-V) had 18 procurements and the single Caucasian patient (hair types II-III) had two procurements. The median healing time was 15days, 11.8days and 8.5days, respectively, per group. Significant complications were encountered, including folliculitis 44%, non-healing wounds 52%, alopecia 16% and visible, hypopigmented scars 3%. One patient had a hypertrophic scar and no hair transfers to the recipient areas were observed. The various hair types correlated with the complications encountered. Five children, with an average burn size of 65.2% (range: 40-85%) died of sepsis. Due to the small sample size, the only statistically significant findings were related to the total body surface area of the burn and the number of times skin was harvested from the scalp, with a p-value of 0.005. The p-values for the healing times related to the first, second and third croppings, were p=0.022, p=0.00032 and p<0.001 respectively.

CONCLUSION

Our study suggests that in pediatric patients of black African descent (hair types VI-VIII) the scalp is not an ideal donor area, due to the unacceptably high incidence of complications. Hence, every precaution should be taken when it becomes necessary to harvest donor skin from the scalp.

Abstract P3-05-03: Metaplastic breast cancers: Genomic profile, mutational burden and TILs

Background: Metaplastic breast cancers (MPBC) are rare, typically triple negative aggressive tumors composed of both, adenocarcinoma and metaplastic elements. Recent evidence that TNBC and MPBC can respond vigorously to immune checkpoint inhibitor therapy (Adams et al, ASCO 2017 and npj Breast Cancer 2017) has prompted the following comprehensive genomic profiling (CGP) and histopathologic assessment of tumor infiltrating lymphocytes (TIL) designed to uncover potential biomarkers of immunotherapy response for MPBC, including mutational burden, Microsatellite Instability (MSI) status and gene amplification of 9p21.4 (or CD274, which includes the PD-L1 locus).

Methods: 12,214 locally aggressive, relapsed and metastatic breast malignancies (mBM) were subjected to CGP using DNA extracted from 40 µm of FFPE sections and adaptor ligation-based libraries to a mean coverage depth &gt;650X for up to 315 cancer-related genes. The results were analyzed for all classes of genomic alterations (GA) including base substitutions, insertions and deletions, select rearrangements, and copy number changes. Tumor mutational burden (TMB) was determined on 1.1 Mbp of sequenced DNA. MSI status was determined by an algorithm based on the sequencing results. TIL were assessed on archived H&E tumor sections and enumerated per guidelines established by the TIL Working Group (Salgado, Ann Oncol 2015) in a subset of MPBC with the highest TMB and compared with low TMBC cases.

Results: 165 of mBM cases were MPBC (1.4%) and are included in this study. All patients were female with a median age of 60 (range 24-86). 165 of the MPBC cases (100%) harbored a wide variety of GA involving more than 100 individual genes. The most common GA were identified in TP53 (65%), followed by PIK3CA (37%). No cases of MSI hi status (0/103) and only one case with amplification of 9p21.4 (1/165, 0.6%) were observed. Most MPBC had a low mutational burden, with a median TMB of 2.7 mutations/Mb (range 0-39.6). Only 11/165 tumors (6.7%) were found to have a TMB over 10 mutations/Mb, including 3 cases (1.8%) with TMB &gt;20. Tumor sections were available for TIL review from 9/11 cases with highest TMB, as well as 11 control cases with lowest TMB. TIL were more frequently observed in high versus low TMB MPBC, with median TIL percentage of 40 and 20 (range 10-80 and range 10-60), respectively, although this difference was not statistically significant (Wilcoxon rank-sum test, p=0.15).

Conclusions: Genomic profiling in the largest cohort of MPBC reported to date confirms that MPBC is enriched for TP53 and PIK3CA mutations and many tumors harbor targetable GA. The frequently observed tumoral PD-L1 expression in MPBC is not based on gene amplification as amplification of 9p21.4 is rare. Most tumors had a low mutation burden, and no significant association of TIL with TMB was observed, suggesting additional processes underlying MPBC immunogenicity.

Citation Format: Taff J, Suh J, Singh B, Denkert C, Troxel AB, Ross JS, Adams S. Metaplastic breast cancers: Genomic profile, mutational burden and TILs [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P3-05-03.