Evaluation of tumor-infiltrating lymphocytes and mammographic density as predictors of response to neoadjuvant systemic therapy in breast cancer

BACKGROUND

Response rates vary among breast cancer patients treated with neoadjuvant systemic therapy (NAST). Thus, there is a need for reliable treatment predictors. Evidence suggests tumor-infiltrating lymphocytes (TILs) predict NAST response. Still, TILs are seldom used clinically as a treatment determinant. Mammographic density (MD) is another potential marker for NAST benefit and its relationship with TILs is unknown. Our aims were to investigate TILs and MD as predictors of NAST response and to study the unexplored relationship between TILs and MD.

MATERIAL AND METHODS

We studied 315 invasive breast carcinomas treated with NAST between 2013 and 2020. Clinicopathological data were retrieved from medical records. The endpoint was defined as pathological complete response (pCR) in the breast. TILs were evaluated in pre-treatment core biopsies and categorized as high (≥10%) or low (<10%). MD was scored (a-d) according to the breast imaging reporting and data system (BI-RADS) fifth edition. Binary logistic regression and Spearman's test of correlation were performed using SPSS.

RESULTS

Out of 315 carcinomas, 136 achieved pCR. 94 carcinomas had high TILs and 215 had low TILs. Six carcinomas had no available TIL data. The number of carcinomas in each BI-RADS category were 37, 122, 112, and 44 for a, b, c, and d, respectively. High TILs were independently associated with pCR (OR: 2.95; 95% CI: 1.59-5.46) compared to low TILs. In the univariable analysis, MD (BI-RADS d vs. a) showed a tendency of higher likelihood for pCR (OR: 2.43; 95% CI: 0.99-5.98). However, the association was non-significant, which is consistent with the result of the multivariable analysis (OR: 2.51; 95% CI: 0.78-8.04). We found no correlation between TILs and MD (0.02; p = .80).

CONCLUSION

TILs significantly predicted NAST response. We could not define MD as a significant predictor of NAST response. These findings should be further replicated.

Low levels of WRAP53 predict decreased efficacy of radiotherapy and are prognostic for local recurrence and death from breast cancer: a long-term follow-up of the SweBCG91RT randomized trial

Downregulation of the DNA repair protein WD40-encoding RNA antisense to p53 (WRAP53) has been associated with radiotherapy resistance and reduced cancer survival. The aim of this study was to evaluate WRAP53 protein and RNA levels as prognostic and predictive markers in the SweBCG91RT trial, in which breast cancer patients were randomized for postoperative radiotherapy. Using tissue microarray and microarray-based gene expression, 965 and 759 tumors were assessed for WRAP53 protein and RNA levels, respectively. Correlation with local recurrence and breast cancer-related death was assessed for prognosis, and the interaction between WRAP53 and radiotherapy in relation to local recurrence was assessed for radioresistance prediction. Tumors with low WRAP53 protein levels had a higher subhazard ratio (SHR) for local recurrence [1.76 (95% CI 1.10-2.79)] and breast cancer-related death [1.55 (1.02-2.38)]. Low WRAP53 RNA levels were associated with almost a three-fold decreased effect of radiotherapy in relation to ipsilateral breast tumor recurrence [IBTR; SHR 0.87 (95% CI 0.44-1.72)] compared with high RNA levels [0.33 (0.19-0.55)], with a significant interaction (P = 0.024). In conclusion, low WRAP53 protein is prognostic for local recurrence and breast cancer-related death. Low WRAP53 RNA is a potential marker for radioresistance.

Combining histological grade, TILs, and the PD-1/PD-L1 pathway to identify immunogenic tumors and de-escalate radiotherapy in early breast cancer: a secondary analysis of a randomized clinical trial

BACKGROUND

The implementation of immunological biomarkers for radiotherapy (RT) individualization in breast cancer requires consideration of tumor-intrinsic factors. This study aimed to investigate whether the integration of histological grade, tumor-infiltrating lymphocytes (TILs), programmed cell death protein-1 (PD-1), and programmed death ligand-1 (PD-L1) can identify tumors with aggressive characteristics that can be downgraded regarding the need for RT.

METHODS

The SweBCG91RT trial included 1178 patients with stage I-IIA breast cancer, randomized to breast-conserving surgery with or without adjuvant RT, and followed for a median time of 15.2 years. Immunohistochemical analyses of TILs, PD-1, and PD-L1 were performed. An activated immune response was defined as stromal TILs ≥10% and PD-1 and/or PD-L1 expression in ≥1% of lymphocytes. Tumors were categorized as high-risk or low-risk using assessments of histological grade and proliferation as measured by gene expression. The risk of ipsilateral breast tumor recurrence (IBTR) and benefit of RT were then analyzed with 10 years follow-up based on the integration of immune activation and tumor-intrinsic risk group.

RESULTS

Among high-risk tumors, an activated immune infiltrate was associated with a reduced risk of IBTR (HR 0.34, 95% CI 0.16 to 0.73, p=0.006). The incidence of IBTR in this group was 12.1% (5.6-25.0) without RT and 4.4% (1.1-16.3) with RT. In contrast, the incidence of IBTR in the high-risk group without an activated immune infiltrate was 29.6% (21.4-40.2) without RT and 12.8% (6.6-23.9) with RT. Among low-risk tumors, no evidence of a favorable prognostic effect of an activated immune infiltrate was seen (HR 2.0, 95% CI 0.87 to 4.6, p=0.100).

CONCLUSIONS

Integrating histological grade and immunological biomarkers can identify tumors with aggressive characteristics but a low risk of IBTR despite a lack of RT boost and systemic therapy. Among high-risk tumors, the risk reduction of IBTR conferred by an activated immune infiltrate is comparable to treatment with RT. These findings may apply to cohorts dominated by estrogen receptor-positive tumors.

Integrating Tumor-Intrinsic and Immunologic Factors to Identify Immunogenic Breast Cancers from a Low-Risk Cohort: Results from the Randomized SweBCG91RT Trial

PURPOSE

The local immune infiltrate's influence on tumor progression may be closely linked to tumor-intrinsic factors. The study aimed to investigate whether integrating immunologic and tumor-intrinsic factors can identify patients from a low-risk cohort who may be candidates for radiotherapy (RT) de-escalation.

EXPERIMENTAL DESIGN

The SweBCG91RT trial included 1,178 patients with stage I to IIA breast cancer, randomized to breast-conserving surgery with or without adjuvant RT, and followed for a median of 15.2 years. We trained two models designed to capture immunologic activity and immunomodulatory tumor-intrinsic qualities, respectively. We then analyzed if combining these two variables could further stratify tumors, allowing for identifying a subgroup where RT de-escalation is feasible, despite clinical indicators of a high risk of ipsilateral breast tumor recurrence (IBTR).

RESULTS

The prognostic effect of the immunologic model could be predicted by the tumor-intrinsic model (Pinteraction = 0.01). By integrating measurements of the immunologic- and tumor-intrinsic models, patients who benefited from an active immune infiltrate could be identified. These patients benefited from standard RT (HR, 0.28; 95% CI, 0.09-0.85; P = 0.025) and had a 5.4% 10-year incidence of IBTR after irradiation despite high-risk genomic indicators and a low frequency of systemic therapy. In contrast, high-risk tumors without an immune infiltrate had a high 10-year incidence of IBTR despite RT treatment (19.5%; 95% CI, 12.2-30.3).

CONCLUSIONS

Integrating tumor-intrinsic and immunologic factors may identify immunogenic tumors in early-stage breast cancer populations dominated by ER-positive tumors. Patients who benefit from an activated immune infiltrate may be candidates for RT de-escalation.

Prognostic and predictive impact of stroma cells defined by PDGFRb expression in early breast cancer: results from the randomized SweBCG91RT trial

Purpose

Predictive biomarkers are needed to aid the individualization of radiotherapy (RT) in breast cancer. Cancer-associated fibroblasts have been implicated in tumor radioresistance and can be identified by platelet-derived growth factor receptor-beta (PDGFRb). This study aims to analyze how PDGFRb expression affects RT benefit in a large randomized RT trial.

Methods

PDGFRb was assessed by immunohistochemistry on tissue microarrays from 989 tumors of the SweBCG91RT trial, which enrolled lymph node-negative, stage I/IIA breast cancer patients randomized to RT after breast-conserving surgery. Outcomes were analyzed at 10 years for ipsilateral breast tumor recurrence (IBTR) and any recurrence and 15 years for breast cancer specific death (BCSD).

Results

PDGFRb expression correlated with estrogen receptor negativity and younger age. An increased risk for any recurrence was noted in univariable analysis for the medium (HR 1.58, CI 95% 1.11–2.23, p = 0.011) or PDGFRb high group (1.49, 1.06–2.10, p = 0.021) compared to the low group. No differences in IBTR or BCSD risk were detected. RT benefit regarding IBTR risk was significant in the PDGFRb low (0.29, 0.12–0.67, p = 0.004) and medium (0.31, 0.16–0.59, p < 0.001) groups but not the PDGFRb high group (0.64, 0.36–1.11, p = 0.110) in multivariable analysis. Likewise, risk reduction for any recurrence was less pronounced in the PDGFRb high group. No significant interaction between RT and PDGFRb-score could be detected.

Conclusion

A higher PDGFRb-score conferred an increased risk of any recurrence, which partly can be explained by its association with estrogen receptor negativity and young age. Reduced RT benefit was noted among patients with high PDGFRb, however without significant interaction.

Immune Infiltrate in the Primary Tumor Predicts Effect of Adjuvant Radiotherapy in Breast Cancer; Results from the Randomized SweBCG91RT Trial

PURPOSE

Tumor-infiltrating immune cells play a key role in tumor progression. The purpose of this study was to analyze whether the immune infiltrate predicts benefit from postoperative radiotherapy in a large randomized breast cancer radiotherapy trial.

EXPERIMENTAL DESIGN

In the SweBCG91RT trial, patients with stage I and II breast cancer were randomized to breast-conserving surgery (BCS) and postoperative radiotherapy or to BCS only and followed for a median time of 15.2 years. The primary tumor immune infiltrate was quantified through two independent methods: IHC and gene expression profiling. For IHC analyses, the absolute stromal area occupied by CD8⁺ T cells and FOXP3⁺ T cells, respectively, was used to define the immune infiltrate. For gene expression analyses, immune cells found to be prognostic in independent datasets were pooled into two groups consisting of antitumoral and protumoral immune cells, respectively.

RESULTS

An antitumoral immune response in the primary tumor was associated with a reduced risk of breast cancer recurrence and predicted less benefit from adjuvant radiotherapy. The interaction between radiotherapy and immune phenotype was significant for any recurrence in both the IHC and gene expression analyses (P = 0.039 and P = 0.035) and was also significant for ipsilateral breast tumor recurrence in the gene expression analyses (P = 0.025).

CONCLUSIONS

Patients with an antitumoral immune infiltrate in the primary tumor have a reduced risk of any recurrence and may derive less benefit from adjuvant radiotherapy. These results may impact decisions regarding postoperative radiotherapy in early breast cancer.

Tumor-infiltrating lymphocytes in ipsilateral breast tumor recurrences predict prognosis

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Background: The antitumoral immune response is dynamic and changes with tumor progression. Previous studies show that immunohistochemical (IHC) assessment of TILs in local recurrences can predict prognosis. It is not clear how adjuvant radiotherapy (RT) can alter the local immune response or if gene expression analyses of TILs in recurrences can provide prognostic information. Methods: Matched biopsies from primary tumors and ipsilateral breast tumor recurrences (IBTRs) from the randomized SweBCG91RT trial were assessed for TILs. Analyses were performed using gene expression (86 matched pairs) and IHC assessment (126 matched pairs). Results: The median time to IBTR was 8.0 years among irradiated patients and 3.6 years among unirradiated patients. In the gene expression analyses, higher absolute values of CD8+ T cells, CD4+ effector memory and CD8+ effector memory T cells in the recurrence could significantly predict a decreased risk of subsequent distant metastasis. In addition, a net increase of these cells in the IBTR compared to the primary tumor was associated with a significantly lower risk of metastasis. TILs did not change significantly between the matched tumors for the whole group or among irradiated patients versus unirradiated patients in the gene expression or IHC analyses. Surprisingly, the group with unchanged TILs levels as measured by IHC had the lowest risk of metastasis while an increase or a decrease in TILs was significantly associated with an increased risk. Conclusions: Cytotoxic and memory T cells in the recurrence protect against subsequent distant metastasis although IHC measurement of TILs could not confirm these results. No significant differences in TILs infiltration between irradiated versus unirradiated patients could be determined in the recurrences. Further analyses including changes of subtypes between the primary tumor and the recurrence will be presented.

Abstract P3-08-08: Prognostic and predictive impact of stroma cells defined by platelet derived growth factor receptor beta in early breast cancer: Results from the randomized SweBGR91RT trial

Background: Although preclinical studies have indicated that stroma cells can modulate the radiosensitivity of tumor cells, non-leukocytic stroma cells have not yet been explored as potential predictive markers for radiotherapy (RT) through systematic analyses of clinical samples. Platelet-derived growth factor receptor beta (PDGFRb) is a key regulator of fibroblasts, pericytes and smooth muscle cells. A high expression of PDGFRb in tumor-associated stroma has previously been associated with worse recurrence free and breast cancer specific survival as well as reduced tamoxifen sensitivity in invasive breast cancer.

Purpose: To analyze the prognostic and predictive impact of stromal PDGFRb regarding ipsilateral breast tumor recurrence (IBTR) and any recurrence in a large randomized RT trial.

Methods: Stromal PDGFRb expression was assessed by immunohistochemical staining of tissue microarrays (TMAs) with 958 tumors from the SweBCG91RT trial (Swedish Breast Cancer Group 91 Radiotherapy). The trial enrolled node-negative, stage I or IIA breast cancer patients, who were randomized to postoperative RT or not after breast conserving surgery. Stained TMAs were evaluated by two independent raters for PDGFRb staining intensity (0/negative; 1/low; 2/moderate; 3/high) and positive stroma fraction (0/0%; 1/1-10%; 2/11-50; 3/51-75%; 4/76-100%). The evaluations of both raters were averaged and the product between the two scoring metrics was formed. For final analysis the data was split in tertiles, as predefined, and referred to as PDGFRb low, medium or high score group. Outcomes were analyzed at 10 years of follow-up.

Results: A high PDGFRb score was correlated with ER negativity (p=0.003,), young age (p&lt;0.001), large tumor size (p=0.058) and high histological grade (p=0.067) in Spearman’s Rank test.

With regard to prognosis, a significantly increased risk for any recurrence was detected in univariable analysis for patients with a medium (HR 1.57, CI95% 1.11-2.23, p=0.011) or high PDGFRb score (HR 1.49, CI95% 1.06-2.10, p=0.021) compared to the PDGFRb low score group. The significance remained for the PDGFRb medium (HR 1.47, CI95% 1.03-2.11, p=0.034) but not the PDGFRb high score group (HR 1.32, CI95% 0.93-1.88, p=0.125) in a multivariable analysis including grade, age and RT.

The benefit of RT regarding the risk of IBTR was significant in the PDGFRb low (HR 0.28, CI95% 0.12-0.65, p=0.003) and medium (HR 0.32, CI95% 0.16-0.61, p=0.001) score groups but not in the PDGFRb high (HR 0.61, CI95% 0.35-1.07, p=0.086) score group in a multivariable analysis including grade and age. The risk reduction from RT regarding any recurrence was also less pronounced in the PDGFRb high (HR 0.73, CI95% 0.48-1.12, p=0.149) score group compared to the PDGFRb low (HR 0.57, CI95 0.32-1.03, p=0.065) and medium (HR 0.46, CI95% 0.28-0.75, p=0.002) score groups in multivariable analysis. No significant interaction between RT and PDGFRb expression could however be detected for IBTR (p=0.14) or any recurrence (p=0.33).

Conclusion: A higher PDGFRb score conferred a negative prognosis with increased risk of any recurrence in univariable analyses, which in part can be explained by its association with ER negativity, young age and grade. A predictive effect of RT benefit from PDGFRb could not be confirmed although a tendency toward less benefit was observed in the patient group with the highest PDGFRb score.

Citation Format: Carina Strell, Reidunn J Edelmann, Axel Stenmark Tullberg, Per Malmström, Mårten Fernö, Arne Östman, Erik Holmberg, Per Karlsson. Prognostic and predictive impact of stroma cells defined by platelet derived growth factor receptor beta in early breast cancer: Results from the randomized SweBGR91RT trial [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P3-08-08.

Abstract PD6-10: A high ratio of CD8/FOXP3 predicts an unfavorable response to postoperative radiotherapy after breast-conserving surgery: Results from the randomized SweBCG91RT trial

Purpose: The effect of postoperative radiotherapy (RT) based on the immune phenotype of tumor-infiltrating lymphocytes (TILs) has not been investigated. The purpose of this study was to analyze how the balance between CD8+ T cells and T regulatory cells (FOXP3+), which have opposite effects on the anti-tumoral defense, affects the risk of ipsilateral breast tumor recurrence (IBTR) and of any recurrence as well as the interaction with RT in a large randomized RT trial.

Methods: In the SweBCG91RT trial, patients with breast cancer stage I and II were randomized to breast conserving surgery (BCS) and postoperative RT or BCS only and followed for a median time of 15.2 years. Tumor blocks were retrieved and stromal TILs were assessed through hematoxylin-eosin stained slides. CD8+ T cells and T regulatory cells were evaluated through staining for CD8 and FOXP3 and the percentage of stroma occupied by CD8+ T cells and T regulatory cells respectively was then calculated. Cutoffs at 5% and 2.5% were used to define high levels of CD8+ T cells (CD8High) and T regulatory cells (FOXP3High), respectively. In total, 943 patients were analyzed.

Results: Among patients who did not receive RT, an increased risk of IBTR and of any recurrence was seen in the CD8Low/FOXP3Low (HR 2.64, CI95% 1.26-5.56, p=0.010 and HR 2.52, CI95% 1.34-4.77, p=0.004, respectively) and CD8High/FOXP3High (HR 1.94, CI95% 0.81-4.63, p=0.135 and HR 2.76, CI95% 1.36-5.57, p=0.005, respectively) groups compared to CD8High/FOXP3Low (HR 1.0) in multivariable analyses including grade and age. The effect of RT on risk of IBTR was more pronounced in the groups with CD8Low/FOXP3Low (HR 0.37, CI95% 0.24-0.57, p&lt;0.001) and CD8High/FOXP3High (HR 0.43, CI95% 0.16-1.13, p=0.086) compared to CD8High/FOXP3Low (HR 0.92, CI95% 0.25-3.40, p=0.905). A potentially unfavorable effect of RT on the risk of any recurrence was observed in the CD8High/FOXP3Low (HR 1.74, CI95% 0.75-4.06, p=0.20) group in contrast to the effect of RT in patients with CD8High/FOXP3High (HR 0.53, CI95% 0.28-1.01, p=0.054) and CD8Low/FOXP3Low (HR 0.48, CI95% 0.34-0.68, p&lt;0.001). A significant interaction between immune phenotype and the effect of RT was found for any recurrence (p=0.024) but not for IBTR (p=0.66).

Conclusions: Our findings suggest that patients with a favorable immune phenotype (CD8High/FOXP3Low) may not derive any benefit from adjuvant RT which could be explained by an interaction through which RT may suppress an activated immune response. These results may have an impact on decisions regarding postoperative RT in early breast cancer.

Citation Format: Axel Stenmark Tullberg, Henri AJ Puttonen, Erik Holmberg, Dan Lundstedt, Fredrika Killander, Emma Niméus, Anikó Kóvacs, Per Karlsson. A high ratio of CD8/FOXP3 predicts an unfavorable response to postoperative radiotherapy after breast-conserving surgery: Results from the randomized SweBCG91RT trial [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr PD6-10.

Effect of Radiotherapy After Breast-Conserving Surgery Depending on the Presence of Tumor-Infiltrating Lymphocytes: A Long-Term Follow-Up of the SweBCG91RT Randomized Trial

PURPOSE

The effects of radiotherapy (RT) on the basis of the presence of stromal tumor infiltrating lymphocytes (TILs) have not been studied. The purpose of this study was to analyze the association of TILs with the effect of postoperative RT on ipsilateral breast tumor recurrence (IBTR) in a large randomized trial.

METHODS

In the SweBCT91RT (Swedish Breast Cancer Group 91 Radiotherapy) trial, 1,178 patients with breast cancer stage I and II were randomly assigned to breast-conserving surgery plus postoperative RT or breast-conserving surgery only and followed for a median of 15.2 years. Tumor blocks were retrieved from 1,003 patients. Stromal TILs were assessed on whole-section hematoxylin-eosin–stained slides using a dichotomized cutoff of 10%. Subtypes were scored using immunohistochemistry on tissue microarray. In total, 936 patients were evaluated.

RESULTS

Altogether, 670 (71%) of patients had TILs less than 10%. In a multivariable regression analysis with IBTR as dependent variable and RT, TILs, subtype, age, and grade as independent variables, RT (hazard ratio [HR], 0.42; 95% CI, 0.29 to 0.61; P < .001), high TILs (HR, 0.61; 95% CI, 0.39 to 0.96, P = .033) grade (3 v 1; HR, 2.17; 95% CI, 1.08 to 4.34; P = .029), and age (≥ 50 v < 50 years; HR, 0.55; 95% CI, 0.38 to 0.80; P = .002) were predictive of IBTR. RT was significantly beneficial in the low TILs group (HR, 0.37; 95% CI, 0.24 to 0.58; P < .001) but not in the high TILs group (HR, 0.58; 95% CI, 0.28 to 1.19; P = .138). The test for interaction between RT and TILs was not statistically significant ( P = .317).

CONCLUSION

This study shows that high values of TILs in the primary tumor independently seem to reduce the risk for an IBTR. Our findings further suggest that patients with breast cancer with low TILs may derive a larger benefit from RT regarding the risk of IBTR.

Positive sentinel node in luminal A-like breast cancer patients - implications for adjuvant chemotherapy?

BACKGROUND

In luminal A-like breast cancer, the indication for adjuvant chemotherapy still is largely based on lymph nodestatus. Sentinel node (SN) positive patients who are no longer recommended an axillary lymph node dissection (ALND) risk undertreatment, especially if they have ≥4 lymph node metastases (LNMs).

AIM

To quantify the group of SN positive luminal A-like patients with ≥4 LNMs and to investigate if the ratio between positive SNs and examined SNs (SN ratio) can provide information of the axillary tumor burden.

MATERIAL AND METHODS

Nearly 370 patients between 2014-2016 in Western Sweden with a clinically node-negative invasive breast cancer treated with both SNB and subsequent ALND were included. SNB findings were compared to ALND findings and the ability of the SN ratio to describe the axillary tumor burden was evaluated using multivariable analysis.

RESULTS

In total,17.6% of patients with luminal A-like tumors had ≥4 LNMs. The SN ratio was statistically significant for predicting ≥4 LNMs among luminal A-like patients (p = .013, OR 1.89 (95% CI 1.14-3.12) per 0.1 increment in SN ratio).

CONCLUSIONS

One sixth of patients with SN positive luminal A-like tumors risk undertreatment. The SN ratio may aid in identifying many of these patients.