503 Background: KEYNOTE-522 (NCT03036488) tested the benefit from adding pembrolizumab (pembro) to chemotherapy (chemo) in patients (pts) with early TNBC. The primary results showed statistically significant and clinically meaningful improvements in pCR and EFS with pembro.Prior studies have shown the prognostic value of the residual cancer burden (RCB) method to quantify the extent of residual disease after neoadjuvant chemo. In this exploratory analysis, we assessed EFS by RCB in KEYNOTE-522. Methods: 1174 pts with previously untreated, nonmetastatic, stage T1c/N1-2 or T2-4/N0-2 TNBC were randomized 2:1 to pembro 200 mg Q3W or placebo (pbo) given with 4 cycles of paclitaxel + carboplatin, then 4 cycles of doxorubicin or epirubicin + cyclophosphamide. After definitive surgery, pts received pembro or pbo for 9 cycles or until recurrence or unacceptable toxicity. Dual primary endpoints are pCR and EFS. RCB was assessed by the local pathologist at the time of surgery. The association between RCB categories (RCB-0, -1, -2, -3, corresponding to increasingly larger residual cancer) and EFS was assessed based on a Cox regression model with treatment as a covariate. Results: Median follow-up was 39.1 months at data cutoff (23 MAR 2021). Pembro shifted RCB to lower categories across the entire spectrum (Table). The HRs (95% CI) for EFS were 0.70 (0.38 - 1.31) for RCB-0 (equivalent to pCR), 0.92 (0.39 - 2.20) for RCB-1, 0.52 (0.32 - 0.82) for RCB-2, and 1.24 (0.69 - 2.23) for RCB-3. The most common EFS event in both arms was distant recurrence, which occurred in fewer pts in the pembro arm in all RCB categories. Conclusions: Increased RCB score was associated with worse EFS. Pts with residual disease had lower RCB values in the pembro arm, including fewer pts with RCB-3. Pembro + chemo prolonged EFS vs chemo alone in the RCB-0, -1, and -2 categories; the small sample size limits interpretation in the RCB-3 category. The small subset of pts with extensive residual disease (RCB-3) in both arms, 5.1% and 6.7%, respectively, had a poor prognosis. These results highlight the importance of neoadjuvant treatment with pembro for improving survival in pts with early TNBC, and identified a subset of pts for whom additional therapies will be needed. Clinical trial information: NCT03036488. [Table: see text]
CDK4/6 inhibitors are approved in combination with hormonotherapy as a first-line intervention against advanced/metastatic hormone receptor (HR)+ HER2- breast cancer, reflecting their ability to extend progression-free survival (PFS) and overall survival (OS) in this patient population.1-3 Nonetheless, >50% of women with HR+ breast cancer receiving CDK4/6 inhibitors ultimately progress and succumb to their disease, owing to hitherto poorly characterized mechanisms of acquired resistance.1-3 While CDK4/6 inhibitors have been conceived to inhibit the proliferation of cancer cells, accumulating preclinical and clinical evidence indicates that they also mediate numerous immunostimulatory effects that may contribute to efficacy.4,5 These observations suggest that hitherto unidentified immunological mechanisms may promote resistance to CDK4/6 inhibitors in patients with HR+HER2- breast cancer.
Methods
We harnessed a unique immunocompetent mouse model that closely recapitulates the immunobiology of human HR+HER2- breast cancer – including a cold tumor microenvironment (TME) coupled to poor sensitivity to PD-1 blockers6 – along with scRNAseq, functional assays and blocking/neutralization experiments to dissect the immunological mechanisms underlying resistance to CDK4/6 inhibitors. The Cancer Genome Atlas (TCGA) was interrogated by in silico analysis. Moreover, immunohistochemistry, multispectral immunofluorescence, and circulating immunophenotyping were performed on samples from 3 independent cohorts of patients with HR+HER2- breast cancer (including longitudinal samples obtained before, during and after CDK4/6 inhibition).
Results
Interleukin 17 (IL17)-producing γδ T cells are recruited to mouse HR+HER2- mammary tumors upon CDK4/6 inhibition through a CCL2-dependent mechanism. In this model, circulating IL17 levels correlate with poor OS, and blocking the γδ TCR, neutralizing IL17 or CCL2 equally improve the therapeutic activity of CDK4/6 inhibitors. Patients from the TCGA with a signature of IL17 signaling have poor OS and signs of immunosuppression in the TME. In diagnostic biopsies from patients with HR+HER2- breast cancer, γδ T cell infiltration correlate with tumor grade, and γδ T cells reside in the proximity of PD-L1+ tumor cells and macrophages. Patients with high activated γδ T cells in the circulation have reduced PFS on CDK4/6 inhibitors as compared to their low counterparts. Circulating CCL2 levels augment during CDK4/6 therapy in progressing patients. Finally, tumor-infiltrating γδ T cells increase as compared to baseline in patients relapsing on CDK4/6 inhibitors.
Conclusions
Our findings prompt the initiation of clinical trials comparing standard-of-care CDK4/6 inhibition plus letrozole vs CDK4/6 inhibition plus letrozole and an IL17 blocker (at least three of which are currently approved for psoriasis treatment) in patients with HR+HER2- breast cancer.
Acknowledgements
This work has been partially sponsored by the 2019 Laura Ziskin Prize in Translational Research (#ZP-6177, PIs: Formenti, McArthur) from the Stand Up to Cancer (SU2C).
References
Im SA, Lu YS, Bardia A, Harbeck N, Colleoni M, Franke F, Chow L, Sohn J, Lee KS, Campos-Gomez S, Villanueva-Vazquez R, Jung KH, Chakravartty A, Hughes G, Gounaris I, Rodriguez-Lorenc K, Taran T, Hurvitz S, Tripathy D. Overall survival with ribociclib plus endocrine therapy in breast cancer. N Engl J Med 2019;381(4):307–316. Turner NC, Slamon DJ, Ro J, Bondarenko I, Im SA, Masuda N, Colleoni M, DeMichele A, Loi S, Verma S, Iwata H, Harbeck N, Loibl S, André F, Puyana Theall K, Huang X, Giorgetti C, Huang Bartlett C, Cristofanilli M. Overall survival with palbociclib and fulvestrant in advanced breast cancer. N Engl J Med 2018;379(20):1926–1936. Slamon DJ, Neven P, Chia S, Fasching PA, De Laurentiis M, Im SA, Petrakova K, Bianchi GV, Esteva FJ, Martín M, Nusch A, Sonke GS, De la Cruz-Merino L, Beck JT, Pivot X, Sondhi M, Wang Y, Chakravartty A, Rodriguez-Lorenc K, Taran T, Jerusalem G. Overall survival ribociclib plus fulvestrant in advanced breast cancer. N Engl J Med 2020;382(6):514–524. Petroni G, Buqué A, Zitvogel L, Kroemer G, Galluzzi L. Immunomodulation by targeted anticancer agents. Cancer Cell 2021;39(3):310–345. Petroni G, Formenti SC, Chen-Kiang S, Galluzzi L. Immunomodulation by anticancer cell cycle inhibitors. Nat Rev Immunol 2020;20(11):669–679. Buqué A, Bloy N, Perez-Lanzón M, Iribarren K, Humeau J, Pol JG, Levesque S, Mondragon L, Yamazaki T, Sato A, Aranda F, Durand S, Boissonnas A, Fucikova J, Senovilla L, Enot D, Hensler M, Kremer M, Stoll G, Hu Y, Massa C, Formenti SC, Seliger B, Elemento O, Spisek R, André F, Zitvogel L, Delaloge S, Kroemer G, Galluzzi L. Immunoprophylactic and immunotherapeutic control of hormone receptor-positive breast cancer. Nat Commun 2020;11(1):3819
Ethics Approval
Mouse experiments were approved by WCM IACUC (#2019-0022). All human studies were on retrospective, fully deidentified samples collected upon informed consent at respective Institutions.
1015 Background: Atezolizumab (anti-PD-L1) plus nab-paclitaxel was shown to improve outcomes in mTBNC in a phase III clinical trial. Subjects were required to be > 12 months from curative-intent therapy in this trial. It remains unknown whether non-taxane chemo + anti-PD-1/L1 will be beneficial in mTNBC, or whether this approach is effective in rapidly-progressing patients ( < 12 mo from curative-intent therapy). Methods: mTNBC patients were enrolled in a phase Ib study of anti-PD-1 (pembro, 200mg IV q3w) plus physician’s choice chemo (cape: n = 14, 2000mg BID, 7d on/7d off; or taxol: n = 14, 80mg/m2 q1w). Primary/secondary objectives were to evaluate safety/tolerability (primary) and RECIST1.1 response (w12). The exploratory objective was to explore for differences in immunomodulation according to chemo choice. Mixed effects models were employed to compare the longitudinal effects of chemo on peripheral immune cells (flow cytometry) and T-cell diversity (Immunoseq assay). Results: Enrollment of the trial is complete (n = 28), with 100% of evaluable patients tolerating therapy (n = 22) as of 2/1/2019. Cape ORR was 43% (5 PR, 1 CR, 2 SD) with median PFS = 155d. Taxol ORR was 25% (1 CR, 1 PR, 3 SD) with median PFS = 99d. Subjects enrolled < 12 months from curative-intent therapy had numerically lower response (ORR = 27%, 1 CR, 2 PR, 3 SD) than subjects without rapid progression (ORR = 45%, 1 CR, 4 PR, 2 SD). No significant differences in immunomodulation were observed according to chemo type, however both cape & taxol were associated with declines in T-cell quantity (CD4 p < .02, CD8 p < .04) and Immunoseq T-cell fraction over time. Conclusions: Pembro plus cape or taxol is safe with encouraging efficacy, however activity may be lower in the setting of rapid progression following curative-intent chemo. Cape+pembro efficacy is favorable with no measurable differences in immunomodulation, and therefore cape may be preferred as a chemo backbone in selected patients. Both cape and taxol are associated with iatrogenic declines in T-cell quantity, which may explain the observed dropoff in anti-PD-1/L1 activity in later lines. Clinical trial information: NCT02734290.
Abstract Background: In KEYNOTE-522 (NCT03036488), neoadjuvant (neoadj) pembrolizumab (pembro) + chemotherapy (chemo) followed by adjuvant (adj) pembro led to statistically significant and clinically meaningful improvements in the primary endpoints, pCR and EFS, vs neoadj placebo (pbo) + chemo followed by adj pbo in patients (pts) with newly diagnosed, high-risk, early TNBC. In the safety population at preplanned interim analysis 4 (IA4), treatment-related AEs in the combined phases (neoadj + adj) occurred in 98.9% of pts with pembro + chemo/pembro and 99.7% of pts with pbo + chemo/pbo; immune-mediated AEs of any grade occurred in 33.5% and 11.3% of pts, respectively. We report additional safety findings, beyond the already reported safety results, on immune-mediated AEs and management in the combined phases from IA4 of KEYNOTE-522. Methods: Eligible pts were randomized 2:1 to receive neoadj pembro 200 mg or pbo Q3W + paclitaxel-carboplatin for 4 cycles and then doxorubicin or epirubicin + cyclophosphamide for 4 cycles. After definitive surgery, pts received radiation therapy as indicated + adj pembro 200 mg or pbo Q3W for up to 9 cycles. Safety was assessed in all randomized pts who received ≥1 dose, underwent surgery, or both. AEs were monitored throughout the study and for 30 d post-treatment (90 d for serious AEs). Results: At IA4 (data cut-off: March 23, 2021), median treatment duration was 13.3 (range, 0-21.9) mo with pembro + chemo/pembro (n = 783) and 13.6 (range, 0-19.8) mo with pbo + chemo/pbo (n = 389). Of 341 pts with immune-mediated AEs and infusion reactions in the pembro + chemo/pembro arm (most events occurred in neoadj phase), 224 had grade 1-2 events and 117 had grade 3–5 events. The most common immune-mediated AEs with pembro + chemo/pembro were hypothyroidism (15.1%) and severe skin reactions (5.7%); infusion reactions occurred in 18.0% of pts (table). Of 118 pts with hypothyroidism, median time to onset was 105 d (range, 7–510 d) and 106 were treated with thyroid replacement, suggesting an endocrine abnormality and need for continued thyroid replacement. Of 45 pts with severe skin reactions, median time to onset was 64 d (range, 4–479 d) and 28 were treated with corticosteroids. Of 141 pts with infusion reactions, median time to onset was 16 d (range, 1–458 d) and 85 were treated with corticosteroids. Other immune-mediated AEs of interest with pembro + chemo/pembro were adrenal insufficiency (2.6%), pneumonitis (2.2%), and hypophysitis (1.9%); most of these events were grade 2–3. All 20 pts with adrenal insufficiency were treated with hormone replacement. Of 17 pts with pneumonitis, median time to onset was 167 d (range, 22-537 d) and 12 were treated with corticosteroids; median episode duration was 92 d. Of 15 pts with hypophysitis, 14 were treated with corticosteroids. Conclusion: In pts with newly diagnosed, high-risk, early TNBC, neoadj pembro + chemo followed by adj pembro had a manageable safety profile that was generally consistent with the known safety profiles of pembro and the chemo regimens. Most immune-mediated AEs and infusion reactions were grade 1-2, manageable with treatment interruption, corticosteroids, and/or hormone replacement therapy, and did not result in treatment discontinuation. Together with the efficacy findings, our results support neoadj pembro + chemo followed by adj pembro as a standard of care regimen for these pts. Table Citation Format: Javier Cortés, Rebecca Dent, Lajos Pusztai, Heather McArthur, Sherko Kuemmel, Carsten Denkert, Yeon Hee Park, Rina Hui, Masato Takahashi, Carlos Barrios, Yalin Zhu, Xiaoli Zhang, Wilbur Pan, Vassiliki Karantza, Joyce O'Shaughnessy, Peter Schmid. Safety evaluation from the KEYNOTE-522 study of neoadjuvant pembrolizumab (or placebo) plus chemotherapy followed by adjuvant pembrolizumab (or placebo) in patients with early triple-negative breast cancer (TNBC) [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PS14-05.
Abstract Background: Black women with breast cancer (BC) have a 40% higher mortality rate compared to Non-Hispanic White (NHW) women. Among women with hormone receptor positive (HR+), human epidermal growth factor receptor 2 negative (HER2-) BC, Black women have worse outcomes than NHW despite comparable systemic therapies. Gene expression profiling assays have been used in early-stage BC to provide prognostic and sometimes predictive information beyond standard immunohistochemical classifications. The 80-gene molecular subtype signature (BluePrint) with the 70-gene risk of distant recurrence signature (MammaPrint®) (Agendia, Irvine, CA) further classify HR+/HER2- BC into luminal A-type, luminal B-type, HER2-type, and basal-type tumors. Luminal B, HER2, and basal-type tumors (non-luminal A) are more aggressive with worse survival outcomes and are overrepresented among Black women. In the metastatic setting, the role of molecular subtype signatures in guiding therapeutic decisions has not yet been determined. We hypothesize that patients with metastatic HR+/HER2- non-luminal A-type BC post-progression on endocrine therapy +/- CKD4/6 inhibition will derive more benefit from chemotherapy than standard-of-care endocrine therapy in the second line setting. We also hypothesize that the impact of the intervention will be more pronounced in Black women compared to NHW women. Methods: This is a randomized phase II study that will evaluate the anti-tumor effect of capecitabine compared to physician’s choice endocrine therapy as second line therapy for adult ( >18 years) patients with non-Luminal A HR+/HER2- metastatic or unresectable locoregional invasive carcinoma (NCT 05693766). The study plans to enroll up to 62 patients. This trial enriches for racial/ethnic minority patients through collaborations with the University of Texas Southwestern and the University of Alabama at Birmingham, two health systems that serve a large minority population. Eligible patients who have received prior endocrine therapy with a CDK4/6 inhibitor will have their tumor tissue analyzed using the MammaPrint® and BluePrint assays. Patients with Luminal A tumors will receive standard of care and will be followed for survival only. Patients with non-Luminal A tumors will be randomized (1:1) to receive physician’s choice endocrine therapy versus capecitabine (dosed at 2000mg twice daily for 7 days on, 7 days off) with stratifications by molecular subtype and race. Patients will be evaluated for response every three cycles using the Response Evaluation Criteria in Solid Tumors. Therapy will be continued until evidence of disease progression or unacceptable major toxicity. The primary endpoint is progression free survival; secondary endpoints are overall response rate, clinical benefit rate, overall survival, and patient reported outcomes. The study will have 80% power to detect a minimal hazard ratio of 0.5 at one-sided significance level of 0.05. Cell-free DNA will be collected at baseline and at three times post-baseline to investigate potential genetic markers of disease response and resistance. Enrollment opened on June 1, 2023. We anticipate opening the trial at the external sites before the end of 2023. Citation Format: Moriah Forster, Jennifer Whisenant, Ben Park, Erica Stringer-Reasor, William Audeh, Andrea Menicucci, Fei Ye, Heather McArthur, Sonya Reid. Integrating gene signatures to guide HR+ MBC therapy in a diverse cohort (INSIGHT) [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-19-09.
Abstract Purpose: To evaluate the association of optoacoustic imaging (OA/US) feature changes with neoadjuvant therapy response and compare with volumetric changes. Methods and Materials: In an IRB approved, HIPAA compliant single arm, single-institution study, 20 breast cancer patients scheduled to undergo neoadjuvant systemic chemotherapy (NAC) were prospectively enrolled to undergo optoacoustic imaging (OA/US) at baseline, prior to cycle 2(Postcycle 1), mid-therapy (mid-chemo)and pre-operative(pre-op) timepoints using a standardized scan protocol. % change in volume was recorded for each timepoint. OA/US features: internal vessels (OAint), total internal hemoglobin (OAHb), internal deoxyHb, external peripheral zone (OApz), boundary zone (OAbz) scored using a previously validated schema. Pathology was collected from standardized reports using residual cancer burden (RCB) and pathologic complete response (pCR) as end points. RCB0-II were classified as responders, RCB-III as non-responders. Descriptive statistics displayed as mean and standard deviation and compared using Wilcoxon Rank-Sum test. Association of volume change was performed using odds ratio (OR) generated from univariate logistic regressions (P-Value < 0.05 for significance). Results: Mean patient age was 50.4 years (SD± 9.5), index cancer size: 26.3mm (SD±9.7). Surgical pathology showed pCR in 6(30%), partial response in 11(55%), no response in 3(15%) cancers, with mean overall residual cellularity of 32.7%(SD±33.5). Mean % residual volume was not significantly different between responders vs nonresponders. [PostCycle 1 (43.7 ± 25.3 vs 38.5 ± 24.8, p=0.7), mid-chemo (64.2 ± 30.9 vs. 65.8 ± 24.6, p=0.8), pre-op (82.9 ± 23.5 vs 89.3 ± 8.4, p=0.9) timepoints. Regression analysis did not show significant correlation of %vol change with pCR at any timepoint (p >0.05). Postcycle 1, OAHb change was significantly higher in patients who had pCR (76.4% vs 108.8%; p=0.02). At pre-op scan, greater decreases were seen in all OA/US scores in cancers that achieved pCR compared to non-pCR [OAbz (25.0% vs. 84.7% P = 0.03; OAint (40.0% vs. 90.3% P = 0.03);OAHb (18.3% vs. 91.8%; P = 0.03); deoxyHb (26.7% vs. 104.8%; P = 0.02), total OAext (25.8% vs. 88.1%; P = 0.03); total internal (16.2% vs. 91.6%; P = 0.03)]. Conclusions: OA/US feature changes demonstrate higher correlation with pCR than volumetric shrinkage in this feasibility study and show promise as a potential tool to non-invasively identify pCR. Table. Percentage Change in Optoacoustic Ultrasound (OA/US) Feature Scores from Baseline, Stratified by (pathologic complete response (pCR). Citation Format: Baṣak Dogan, Berat Bersu Ozcan, Heather McArthur, Yan Peng. Changes in Breast Cancer Optoacoustic Imaging Features During Neoadjuvant Therapy and Correlation with Pathologic Response: A feasibility study [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO5-26-02.
Background Chemoimmunotherapy is a standard treatment for triple-negative breast cancer (TNBC), however, the impacts of different chemotherapies on T-cell populations, which could correlate with clinical activity, are not known. Quantifying T-cell populations with flow cytometry and T-cell receptor (TCR) immunosequencing may improve our understanding of how chemoimmunotherapy affects T-cell subsets, and to what extent clonal shifts occur during treatment. TCR immunosequencing of intratumoral T cells may facilitate the identification and monitoring of putatively tumor-reactive T-cell clones within the blood. Methods Blood and tumor biopsies were collected from patients with metastatic TNBC enrolled in a phase Ib clinical trial of first or second-line pembrolizumab with paclitaxel or capecitabine. Using identical biospecimen processing protocols, blood samples from a cohort of patients treated for early-stage breast cancer were obtained for comparison. Treatment-related immunological changes in peripheral blood and intratumoral T cells were characterized using flow cytometry and TCR immunosequencing. Clonal proliferation rates of T cells were compared based on intratumoral enrichment. Results When combined with pembrolizumab, paclitaxel and capecitabine resulted in similar time-dependent lymphodepletions across measured peripheral T-cell subsets. Their effects were more modest than that observed following curative-intent dose-dense anthracycline and cyclophosphamide (ddAC) (average fold-change in CD3 + cells, capecitabine: −0.42, paclitaxel: −0.56, ddAC: −1.21). No differences in T-cell clonality or richness were observed following capecitabine or paclitaxel-based treatments. Regression modeling identified differences in the emergence of novel T-cell clones that were not detected at baseline (odds compared with ddAC, capecitabine: 0.292, paclitaxel: 0.652). Pembrolizumab with paclitaxel or capecitabine expanded T-cell clones within tumors; however, these clones did not always expand within the blood. Proliferation rates within the blood were similar between clones that were enriched and those that were not enriched within tumors. Conclusion Chemoimmunotherapy for metastatic TNBC with pembrolizumab and capecitabine or paclitaxel resulted in similar peripheral T-cell subset lymphodepletion without altering T-cell clonal diversity. Regression modeling methods are applicable in immune monitoring studies, such as this to identify the odds of novel T-cell clones emerging during treatment, and proliferation rates of tumor-enriched T-cell clones.
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