Eileen P. Connolly

High-dose radiotherapy (RT) in cancer is immunogenic but also induces an immunosuppressive tumor microenvironment (TME) that limits the efficacy of immune checkpoint inhibitors (ICIs). Overcoming this immunosuppressive barrier is critical to unlocking the full potential of RT-ICI combinations. As Notch signaling regulates TME, we hypothesized that the γ-secretase inhibitor (GSI), AL101, would suppress radiation-induced immunosuppression and enhance antitumor efficacy when combined with RT and anti-PD-1 (aPD-1) therapy.Syngeneic neuroblastoma (9464D) and triple-negative breast cancer (EO771) tumors were established in C57BL/6, macrophage-depleted C57BL/6 mice, or athymic mice. Mice received 12 Gy RT, AL101, and aPD-1. Tumors were analyzed by spectral flow cytometry and single-cell RNA sequencing (scRNA-seq), and lung metastases were evaluated histologically.The triple combination of RT, aPD-1, and GSI produced durable tumor growth inhibition and significantly prolonged survival in both models compared to all other treatment groups. Triple therapy also markedly reduced lung metastases in EO771 mice. These effects were abrogated in athymic nude mice and macrophage-depleted immunocompetent mice. Based on scRNA-seq and spectral flow cytometry analysis, RT alone increased exhausted T cells and immunosuppressive macrophages, while triple therapy reversed these effects, including expansion of activated CD8+ T cells, reduction of Tregs and exhausted T cells, restoration of cross-presenting CD103+ dendritic cells, and reprogramming of myeloid cells toward a proinflammatory state.GSI remodels RT-induced immunosuppressive TME and potentiates the efficacy of RT + ICI. GSI combined with RT+aPD-1 reprograms the TME toward an immunostimulatory state and supports GSI as a promising immuno-radiotherapeutic strategy.

Background: Optimal sequencing of mastectomy, tissue expander breast reconstruction (TE-BR), chemotherapy, and post-mastectomy radiotherapy (PMRT) remains unclear. While PMRT is known to impact TE-BR outcomes, limited data exist comparing outcomes between patients who also receive neoadjuvant chemotherapy (NAC) versus adjuvant chemotherapy (AC).Methods: A retrospective review of 126 patients diagnosed with invasive breast carcinoma who underwent mastectomy, TE-BR, and PMRT between 2001 and 2017 was conducted. Patients were stratified into NAC (n=74) and AC (n=52) cohorts. Logistic regression and Kaplan-Meier analyses evaluated TE-BR failure rates, completion rates, and radiation toxicity. Multivariate Cox proportional hazard regression modeled TE-BR failure probability.Results: TE-BR failure rates were significantly higher in the NAC group (44.6% at a median of 18.7 months) compared to the AC group (26.9% at 23.2 months, p=0.041). Moreover, NAC was associated with increased adverse events and lower TE-BR completion rates (both p=0.001). Univariate analysis identified NAC (p=0.007) and acute RT toxicity (p<0.001) as predictors of TE-BR failure. Multivariate analysis confirmed NAC (HR 2.73, p=0.003) and acute RT toxicity (HR 3.16, p<0.001) as independent risk factors. Acute RT toxicity rates were similar between NAC and AC groups (p=0.604). Completing TE expansion before PMRT in NAC patients was linked to higher failure probability (HR 2.58, p=0.023).Conclusion: Our study is the first to report TE-BR outcomes in women who undergo NAC versus AC in the context of PMRT. Our findings indicate inferior TE-BR outcomes following NAC when PMRT is delivered, emphasizing the importance of shared decision-making between patients and doctors about optimal surgical choice. If eligible, breast conservation or alternate BR technique should be strongly considered in the setting of NAC and future research should explore optimal reconstruction strategies.

ENHANCE-1 was a phase Ib/II study which evaluated eribulin plus pembrolizumab as a treatment for metastatic triple negative breast cancer (mTNBC). All patients had measurable disease and up to 2 prior systemic treatments. We identified 142 patients with available samples and evaluated associations between the pre-treatment tumor-immune microenvironment and response using diagnostic H&Es and multiplexed immunofluorescence with 2 antibody panels. Markers were chosen to evaluate lymphocytes and myeloid cells including: CD4, CD8, FoxP3, CD56, CD20, CD68, CD163, Vimentin, and HLA-DR. While H&E-assessed computational and manual assessments of stromal tumor infiltrating lymphocytes (sTILs) did not associate with response, multiplex immunofluorescence revealed several significant associations. These include enrichment of stromal CD56+ in non-responders and higher stromal CD4 + CD8+ in non-responders in breast samples. Responders exhibited higher stromal macrophage populations CD68 + , CD68+Vimentin + , CD68 + CD163+Vimentin+ as well as higher stromal HLA-DR + . Our results suggest that further studies on immune cell populations other than T-cells as predictive biomarkers for combination therapies in mTNBC are warranted.

MYCN-amplified neuroblastoma often presents as a highly aggressive metastatic disease with a poor prognosis. Activating transcription factor 5 (ATF5) is implicated in neural cell differentiation and cancer cell survival. Here, we show that ATF5 is highly expressed in patients with stage 4 high-risk neuroblastoma, with increased expression correlating with a poorer prognosis. We demonstrated that ATF5 promotes the metastasis of neuroblastoma cell lines in vivo. Functionally, ATF5 depletion significantly reduced xenograft tumor growth and metastasis of neuroblastoma cells to the bone marrow and liver. Mechanistically, ATF5 endows tumor cells with resistance to anoikis, thereby increasing their survival in systemic circulation and facilitating metastasis. We identified the proapoptotic BCL-2 modifying factor (BMF) as a critical player in ATF5-regulated neuroblastoma anoikis. ATF5 suppresses BMF under suspension conditions at the transcriptional level, promoting anoikis resistance, whereas BMF knockdown significantly prevents ATF5 depletion–induced anoikis. Therapeutically, we showed that a cell-penetrating dominant-negative ATF5 peptide, CP-d/n-ATF5, inhibits neuroblastoma metastasis to the bone marrow and liver by inducing anoikis sensitivity in circulating tumor cells. Our study identified ATF5 as a metastasis promoter and CP-d/n-ATF5 as a potential antimetastatic therapeutic agent for neuroblastoma.Significance:This study shows that resistance to anoikis in neuroblastoma is mediated by ATF5 and offers a rationale for targeting ATF5 to treat metastatic neuroblastoma.

MYCN-amplified neuroblastoma often presents as a highly aggressive metastatic disease with a poor prognosis. Activating transcription factor 5 (ATF5) is implicated in neural cell differentiation and cancer cell survival. Here, we show that ATF5 is highly expressed in patients with stage 4 high-risk neuroblastoma, with increased expression correlating with a poorer prognosis. We demonstrated that ATF5 promotes the metastasis of neuroblastoma cell lines in vivo. Functionally, ATF5 depletion significantly reduced xenograft tumor growth and metastasis of neuroblastoma cells to the bone marrow and liver. Mechanistically, ATF5 endows tumor cells with resistance to anoikis, thereby increasing their survival in systemic circulation and facilitating metastasis. We identified the proapoptotic BCL-2 modifying factor (BMF) as a critical player in ATF5-regulated neuroblastoma anoikis. ATF5 suppresses BMF under suspension conditions at the transcriptional level, promoting anoikis resistance, whereas BMF knockdown significantly prevents ATF5 depletion–induced anoikis. Therapeutically, we showed that a cell-penetrating dominant-negative ATF5 peptide, CP-d/n-ATF5, inhibits neuroblastoma metastasis to the bone marrow and liver by inducing anoikis sensitivity in circulating tumor cells. Our study identified ATF5 as a metastasis promoter and CP-d/n-ATF5 as a potential antimetastatic therapeutic agent for neuroblastoma.Significance:This study shows that resistance to anoikis in neuroblastoma is mediated by ATF5 and offers a rationale for targeting ATF5 to treat metastatic neuroblastoma.

MYCN-amplified neuroblastoma often presents as a highly aggressive metastatic disease with a poor prognosis. Activating transcription factor 5 (ATF5) is implicated in neural cell differentiation and cancer cell survival. Here, we show that ATF5 is highly expressed in patients with stage 4 high-risk neuroblastoma, with increased expression correlating with a poorer prognosis. We demonstrated that ATF5 promotes the metastasis of neuroblastoma cell lines in vivo. Functionally, ATF5 depletion significantly reduced xenograft tumor growth and metastasis of neuroblastoma cells to the bone marrow and liver. Mechanistically, ATF5 endows tumor cells with resistance to anoikis, thereby increasing their survival in systemic circulation and facilitating metastasis. We identified the proapoptotic BCL-2 modifying factor (BMF) as a critical player in ATF5-regulated neuroblastoma anoikis. ATF5 suppresses BMF under suspension conditions at the transcriptional level, promoting anoikis resistance, whereas BMF knockdown significantly prevents ATF5 depletion–induced anoikis. Therapeutically, we showed that a cell-penetrating dominant-negative ATF5 peptide, CP-d/n-ATF5, inhibits neuroblastoma metastasis to the bone marrow and liver by inducing anoikis sensitivity in circulating tumor cells. Our study identified ATF5 as a metastasis promoter and CP-d/n-ATF5 as a potential antimetastatic therapeutic agent for neuroblastoma. Significance: This study shows that resistance to anoikis in neuroblastoma is mediated by ATF5 and offers a rationale for targeting ATF5 to treat metastatic neuroblastoma.

Importance: Little is known about regional nodal irradiation (RNI) practice patterns or rates of locoregional recurrence (LRR) with and without RNI in patients with limited nodal disease and favorable biology treated with modern surgical and systemic therapy, including approaches that de-escalate those latter treatments.Objective: To investigate how often patients with low–recurrence score breast cancer with 1 to 3 nodes involved receive RNI, incidence and predictors of LRR, and associations between locoregional therapy and disease-free survival.Design, Setting, and Participants: In this secondary analysis of the SWOG S1007 trial, patients with hormone receptor-positive, ERBB2-negative breast cancer, and a Oncotype DX 21-gene Breast Recurrence Score assay result of no more than 25, were randomized to endocrine therapy alone vs chemotherapy then endocrine therapy. Prospectively collected radiotherapy information was collected from 4871 patients treated in diverse settings. Data were analyzed June 2022 to April 2023.Exposure: Receipt of RNI (targeting at least the supraclavicular region).Main Outcome(s) and Measure(s): Cumulative incidence of LRR was calculated by locoregional treatment received. Analyses were assessed for associations between invasive disease-free survival (IDFS) and locoregional therapy, adjusted for menopausal status, treatment group, recurrence score, tumor size, nodes involved, and axillary surgery. Radiotherapy information was recorded in the first year after randomization, so survival analyses were landmarked as starting at 1 year among those still at risk.Results: Of 4871 female patients (median [range] age, 57 [18-87] years) with radiotherapy forms, 3947 (81.0%) reported radiotherapy receipt. Of 3852 patients who received radiotherapy and had complete information on targets, 2274 (59.0%) received RNI. With a median follow-up of 6.1 years, the cumulative incidence of LRR by 5 years was 0.85% among patients who received breast-conserving surgery and radiotherapy with RNI; 0.55% after breast-conserving surgery with radiotherapy without RNI; 0.11% after mastectomy with postmastectomy radiotherapy; and 1.7% after mastectomy without radiotherapy. Similarly low LRR was observed within the group assigned to endocrine therapy without chemotherapy. The rate of IDFS did not differ by RNI receipt (premenopausal: hazard ratio [HR], 1.03; 95% CI, 0.74-1.43; P = .87; postmenopausal: HR, 0.85; 95% CI, 0.68-1.07; P = .16).Conclusions and Relevance: In this secondary analysis of a clinical trial, RNI use was divided in the setting of biologically favorable N1 disease, and rates of LRR were low even in patients who did not receive RNI. Disease-free survival was not associated with RNI receipt; omission of chemotherapy among patients similar to those enrolled in the S1007 trial is not an independent indication for use of RNI.

Purpose/Objective: We present our single-institution experience in the management of invasive breast cancer with targeted intraoperative radiotherapy (TARGIT-IORT), focusing on patient suitability for IORT determined by the American Society for Radiation Oncology (ASTRO) Accelerated Partial Breast Irradiation (APBI) consensus guidelines.Materials/Methods: We identified 237 patients treated for biopsy-proven early-stage invasive breast cancer using low energy x-ray TARGIT-IORT at the time of lumpectomy between September 2013 and April 2020 who were prospectively enrolled in an institutional review board (IRB) approved database. We retrospectively reviewed preoperative and postoperative clinicopathologic factors to determine each patient’s ASTRO APBI suitability (suitable, cautionary or unsuitable) according to the 2017 consensus guidelines (CG). Change in suitability group was determined based on final pathology. Kaplan-Meier methods were used to estimate the survival probability and recurrence probability across time.Results: 237 patients were included in this analysis, based on preoperative clinicopathologic characteristics, 191 (80.6%) patients were suitable, 46 (19.4%) were cautionary and none were deemed unsuitable. Suitability classification changed in 95 (40%) patients based on final pathology from lumpectomy. Increasing preoperative lesion size or a body mass index (BMI) ≥ 30 kg/m² were significant predictors for suitability group change. Forty-one (17.3%) patients received additional adjuvant whole breast radiotherapy after TARGIT-IORT. At a median follow up of 38.2 months (range 0.4 – 74.5), five (2.1%) patients had ipsilateral breast tumor recurrences (IBTR), including two (0.8%) true local recurrences defined as a recurrence in the same quadrant as the initial lumpectomy bed with the same histology as the initial tumor. IBTR occurred in 1/103 (0.09%) patient in the post-op suitable group, 4/98 (4.08%) patients in the post-op cautionary group, and no patients in the post-op unsuitable group. At 3-years, the overall survival rate was 98.4% and the local recurrence free survival rate was 97.1%.Conclusion: There is a low rate of IBTR after TARGIT-IORT when used in appropriately selected patients. Change in suitability classification pre to postoperatively is common, highlighting a need for further investigation to optimize preoperative patient risk stratification in this setting. Patients who become cautionary or unsuitable based on final pathology should be considered for additional adjuvant therapy.