Activation of PI3K signaling is frequently observed in triple-negative breast cancer (TNBC), yet PI3K inhibitors have shown limited clinical activity. To investigate intrinsic and adaptive mechanisms ...of resistance, we analyzed a panel of patient-derived xenograft models of TNBC with varying responsiveness to buparlisib, a pan-PI3K inhibitor. In a subset of patient-derived xenografts, resistance was associated with incomplete inhibition of PI3K signaling and upregulated MAPK/MEK signaling in response to buparlisib. Outlier phosphoproteome and kinome analyses identified novel candidates functionally important to buparlisib resistance, including NEK9 and MAP2K4. Knockdown of NEK9 or MAP2K4 reduced both baseline and feedback MAPK/MEK signaling and showed synthetic lethality with buparlisib
A complex in/del frameshift in
decreased sensitivity to buparlisib via NEK9/MAP2K4-dependent mechanisms. In summary, our study supports a role for NEK9 and MAP2K4 in mediating buparlisib resistance and demonstrates the value of unbiased omic analyses in uncovering resistance mechanisms to targeted therapy.
Integrative phosphoproteogenomic analysis is used to determine intrinsic resistance mechanisms of triple-negative breast tumors to PI3K inhibition.
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ABSTRACT
Despite the success of approved systemic therapies for estrogen receptor α (ER)‐positive breast cancer, drug resistance remains common. We hypothesized that secreted factors from the human ...tumor microenvironment could modulate drug resistance. We previously screened a library of 297 recombinant‐secreted microenvironmental proteins for the ability to confer resistance to the anti‐estrogen fulvestrant in 2 ER+ breast cancer cell lines. Herein, we considered whether factors that enhanced drug sensitivity could be repurposed as therapeutics and provide leads for drug development. Screening data revealed bone morphogenic protein (BMP)4 as a factor that inhibited cell growth and synergized with approved anti‐estrogens and cyclin‐dependent kinase 4/6 inhibitors (CDK4/6i). BMP4‐mediated growth inhibition was dependent on type I receptor activin receptor‐like kinase (ALK)3‐dependent phosphorylation (P) of mothers against decapentaplegic homolog (SMAD/P‐SMAD)1 and 5, which could be reversed by BMP receptor inhibitors and ALK3 knockdown. The primary effect of BMP4 on cell fate was cell‐cycle arrest, in which RNA sequencing, immunoblot analysis, and RNA interference revealed to be dependent on p2iWAF1/Cip1 upregulation. BMP4 also enhanced sensitivity to approved inhibitors of mammalian target of rapamycin complex 1 and CDK4/6 via ALK3‐mediated P‐SMAD1/5 and p21 upregulation in anti‐estrogen‐resistant cells. Patients bearing primary ER+ breast tumors, exhibiting a transcriptomic signature of BMP4 signaling, had improved disease outcome following adjuvant treatment with anti‐estrogen therapy, independently of age, tumor grade, and tumor stage. Furthermore, a transcriptomic signature of BMP4 signaling was predictive of an improved biologic response to the CDK4/6i palbociclib, in combination with an aromatase inhibitor in primary tumors. These findings highlight BMP4 and its downstream pathway activation as a therapeutic opportunity in ER+ breast cancer.—Shee, K., Jiang, A., Varn, F. S., Liu, S., Traphagen, N. A., Owens, P., Ma, C. X., Hoog, J., Cheng, C., Golub, T. R., Straussman, R., Miller, T. W. Cytokine sensitivity screening highlights BMP4 pathway signaling as a therapeutic opportunity in ER+ breast cancer. FASEB J. 33, 1644–1657 (2019). www.fasebj.org
Current treatment approaches for renal cell carcinoma (RCC) face challenges in achieving durable tumor responses due to tumor heterogeneity and drug resistance. Combination therapies that leverage ...tumor molecular profiles could offer an avenue for enhancing treatment efficacy and addressing the limitations of current therapies. To identify effective strategies for treating RCC, we selected ten drugs guided by tumor biology to test in six RCC patient-derived xenograft (PDX) models. The multitargeted tyrosine kinase inhibitor (TKI) cabozantinib and mTORC1/2 inhibitor sapanisertib emerged as the most effective drugs, particularly when combined. The combination demonstrated favorable tolerability and inhibited tumor growth or induced tumor regression in all models, including two from patients who experienced treatment failure with FDA-approved TKI and immunotherapy combinations. In cabozantinib-treated samples, imaging analysis revealed a significant reduction in vascular density, and single-nucleus RNA sequencing (snRNA-seq) analysis indicated a decreased proportion of endothelial cells in the tumors. SnRNA-seq data further identified a tumor subpopulation enriched with cell-cycle activity that exhibited heightened sensitivity to the cabozantinib and sapanisertib combination. Conversely, activation of the epithelial-mesenchymal transition pathway, detected at the protein level, was associated with drug resistance in residual tumors following combination treatment. The combination effectively restrained ERK phosphorylation and reduced expression of ERK downstream transcription factors and their target genes implicated in cell-cycle control and apoptosis. This study highlights the potential of the cabozantinib plus sapanisertib combination as a promising treatment approach for patients with RCC, particularly those whose tumors progressed on immune checkpoint inhibitors and other TKIs.
The molecular-guided therapeutic strategy of combining cabozantinib and sapanisertib restrains ERK activity to effectively suppress growth of renal cell carcinomas, including those unresponsive to immune checkpoint inhibitors.
Aberrant expression of nuclear transporters and deregulated subcellular localization of their cargo proteins are emerging as drivers and therapeutic targets of cancer. Here, we present evidence that ...the nuclear exporter exportin-6 and its cargo profilin-1 constitute a functionally important and frequently deregulated axis in cancer. Exportin-6 upregulation occurs in numerous cancer types and is associated with poor patient survival. Reducing exportin-6 level in breast cancer cells triggers antitumor effects by accumulating nuclear profilin-1. Mechanistically, nuclear profilin-1 interacts with eleven-nineteen-leukemia protein (ENL) within the super elongation complex (SEC) and inhibits the ability of the SEC to drive transcription of numerous pro-cancer genes including MYC. XPO6 and MYC are positively correlated across diverse cancer types including breast cancer. Therapeutically, exportin-6 loss sensitizes breast cancer cells to the bromodomain and extra-terminal (BET) inhibitor JQ1. Thus, exportin-6 upregulation is a previously unrecognized cancer driver event by spatially inhibiting nuclear profilin-1 as a tumor suppressor.
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•The highly selective nuclear exporter exportin-6 is frequently upregulated in cancer•Nuclear export of profilin-1 underlies the pro-cancer activity of exportin-6•Nuclear profilin-1 inhibits super elongation complex and pro-cancer gene expression•Exportin-6 loss sensitizes breast cancer cells to BET bromodomain inhibitor
By defining the moonlighting function of the small actin-binding protein profilin-1 in the nucleus as a transcriptional repressor and the prevalent upregulation of its nuclear exporter exportin-6 in diverse cancer types, Zhu et al. show that deregulation of protein subcellular localization is an important non-oncogene addiction with strong therapeutic potential.
Abstract
Background: Neoadjuvant ET (NET) offers an opportunity to assess ET sensitivity for ER+ HER2- BC and potentially to tailor therapy. Ki67 >10% on biopsy after 2-4 weeks (wks) of NET ...identifies patients (pts) with intrinsic ET resistance; while pathologic complete response (pCR) and modified preoperative endocrine prognostic index of 0 (mPEPI 0: pT1-2N0, Ki67 ≤2.7%) at surgery indicates sensitivity to ET. However, on-NET biopsy is not always acceptable or feasible and delays the ET sensitivity determination. PAM50 ROR score and intrinsic subtypes by tumor RNA profiling are prognostic in pts with early stage ER+ HER2- BC, and predict pCR rates to neoadjuvant chemotherapy (NCT) (PMC2667820). We therefore hypothesized that PAM50 analysis on pre-NET biopsies could predict the likelihood of a) a high on-NET Ki67, b) mPEPI-0 or pCR at surgery and, c) pCR for pts triaged to NCT. Methods: The ALTERNATE trial is a phase III study that randomized postmenopausal pts with clinical stage II/III ER+ (Allred score 6-8) HER2- BC to receive neoadjuvant anastrozole, fulvestrant, or both for 6 months before surgery. Research biopsy was required at pre-NET and wk 4, then optional at wk 12. Pts with Ki67 >10% on biopsy at wk 4 or 12 discontinued NET and were offered NCT. PAM50 intrinsic subtype and ROR-P values were generated from mRNA sequencing (RNASeq) analysis on pre-NET biopsies using open-source informatics (PMC7723687) and evaluated for prediction of on-NET Ki67 >10% at wk 4 or 12, pCR or mPEPI-0 post NET, and pCR post NCT. Results: 749 of 1,297 eligible trial pts were included in the analyses, after excluding 548 pts due to insufficient pre-NET tumor for RNASeq (n=511) or PAM50 normal subtype (n=37). Similar to the entire ALTERNATE population, the rate of Ki67 >10% at wk 4 or 12 was 24.4% (95% CI: 21.4-27.7%) and the rate of mPEPI-0/pCR post NET was 19.8% (95% CI: 17.0-22.8%). There were 393 (52.5%) Lum A, 302 (40.3%) Lum B, and 54 (7.2%) non-Lum (9 Basal, 45 HER2-E) BCs. These included 196 (26.2%) ROR-P low, 354 (47.3%) ROR-P medium and 199 (26.6%) ROR-P high BCs. Both the rates of Ki67 >10% at wk 4 or 12 and mPEPI-0/pCR differed significantly with respect to PAM50 subtype or ROR-P category, such that Lum A or ROR-P low BCs were least likely to have a Ki67 >10% at wk 4 or 12 and most likely to achieve mPEPI-0/pCR (Table).
93 of 168 (55.4%) pts triaged to NCT had RNA-seq results, yielding 26 Lum A, 49 Lum B, 4 Basal and 14 HER2-E, with the pCR rates of 0%, 6.1%, 0%, and 21.4%, respectively. There were 10 ROR-P low, 39 medium, and 44 high tumors, with a pCR rate of 0%, 5.1% and 9.1%, respectively. Conclusion: These data indicate that both baseline ROR-P and intrinsic subtype are predictive of early on-NET Ki67 > 10% and mPEPI 0/pCR at surgery after NET. For pts triaged to NCT based on an early on-NET Ki67 >10%, the HER2-E group had the highest pCR rate (20%) and no pCRs were observed in Lum A. These data may be useful for directing neoadjuvant therapy in postmenopausal pts with ER+ HER2- BC. Support: U10CA180821, U10CA180882, U24CA196171, UG1CA189856, U10CA180868 (NRG), NCI BIQSFP, BCRF, Genentech, AstraZeneca. https://acknowledgments.alliancefound.org. (MJE) CPRIT RR140033, P50CA186784, P50-CA58223, U01 CA214125, U24CA210954, Gift from Ralph and Lisa Eads, McNair Scholarship. Trials.gov Identifier: NCT01953588.
Table 1.Rates of Ki67 >10% and mPEPI-0/pCR post NET by PAM50 subtype and ROR-P categoryKi67 >10% at wk 4 or 12mPEPI 0/pCR post NETPAM50 SubtypenYes, n (%)PnNo, n (%)PLum A37251 (13.7%) 95% CI: 10.4-17.6%<0.0001393104 (26.5%) 95%CI: 22.2-31.1%<0.0001Lum B29394 (32.1%) 95% CI: 26.8-37.8%30243 (14.2%) 95%CI: 10.5-18.7%Non-luminal (Basal and HER2-E)5338 (71.7%) 95%CI: 57.6-83.2%541 (1.9%) 95%CI: 0.05-9.9%ROR-P CategorynYes, n (%)PnNo, n (%)PLow18018 (10.0%) 95%CI: 6.0-15.3%<0.000119660 (30.6%) 95%CI: 24.2-37.6%<0.0001Intermediate34474 (21.5%) 95%CI: 17.3-26.2%35471 (20.1%) 95%CI: 16.0-24.6%High19491 (46.9%) 95%CI: 39.7-54.2%19917 (8.5%) 95%CI: 5.1-13.3%
Citation Format: Cynthia X Ma, Meenakshi Anurag, Travis Dockter, Jeremy Hoog, Aranzazu Fernandez-Martinez, Cheng Fan, Richard Gibbs, Souzan Sanati, Kiran Vij, Mark Watson, Olwen Hahn, Joseph Guenther, Abigail Caudle, Erika Crouch, Amy Tiersten, Monica Mita, Wajeeha Razaq, Tina J Hieken, Yang Wang, A. Marilyn Leitch, Gary W Unzeitig, Anna Weiss, Eric P Winer, Kelly Hunt, Ann H Partridge, Lisa A Carey, Charles M Perou, Matthew J Ellis, Vera Suman. Pam50 intrinsic subtype and risk of recurrence score (ROR) for the prediction of endocrine (ET) sensitivity and pathologic response to chemotherapy in postmenopausal women with clinical stage II/III estrogen receptor positive (ER+) and HER2 negative (HER2-) breast cancer (BC) in the alternate trial (Alliance A011106) abstract. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr PD9-03.
Abstract
Background: NET is offered to postmenopausal patients (pts) with clinical stage 2/3 ER+/HER2- BC to promote breast-conserving surgery. Also limited surgical accessibility during the COVID19 ...pandemic has increased NET utility. Inability to identify ET-resistant disease at diagnosis risks disease progression (PD) and delays more effective treatments. Dowsett et al. recently demonstrated that baseline levels of ER, progesterone receptor (PR), Ki67 (>15% vs ≤15%), and Ki67 (>10% vs ≤10%) 2-4 weeks (wks) after starting NET may improve appropriate patient (pt) selection for NET (PMC7280290). The ER, PR and Ki67-based prediction model divides pts with primary ER+/HER2- BC into 3 groups for appropriateness for NET: (Group 1) NET is likely to be inappropriate (Allred ER <6 or ER 6 and PgR <6), (Group 2) NET may be appropriate and a biopsy for on-treatment Ki67 analysis may be considered after 2-4 wks of NET (2A: ER 7 or 8 and PgR <6 and 2B: ER 6 or 7 and PgR ≥6) given that on-treatment Ki67 >10% has been associated with worse outcome (PMC5455353), or (Group 3) NET is appropriate (ER 8 and PgR ≥6). The ALTERNATE trial (NCT01953588) randomized postmenopausal women with clinical stage II or III, ER+ (Allred score 6-8)/HER2- BC to receive anastrozole (ANA), fulvestrant (FUL), or ANA + FUL for 6 months, unless Ki67 was >10% on wk 4 or 12 biopsy, in which case pts were triaged to receive neoadjuvant chemotherapy (NCT) or surgery. As previously reported, the ET-sensitive disease (mPEPI 0 plus pCR) rates were similar across the treatment arms and overall 22% (286 of 1,299) pts had Ki67 >10% at wk 4 or 12. The ALTERNATE trial therefore provides a large independent data set to evaluate the NET appropriateness model.
Results: Among 1,299 eligible pts randomized to receive 6 months of NET, 214 were excluded due to absent HR Allred score (n=41) or absence of pre-treatment and wk 4 Ki67 determinations (n=173). The proportions of the remaining 1,085 pts in Group 1, 2 and 3 were 1% (n=10), 43% (n= 468), and 56% (n=607), respectively. On-study Ki67 >10% prompting conversion from NET to NCT/Surgery occurred in: Group 1 90% (9 of 10), Group 2 30% (141 of 468), and Group 3 17% (104 of 607) (Table 1). Among the 1,075 pts in Groups 2 and 3, 260 (24%) pts had Ki67 ≤15% at baseline (BL), among whom only 14 (5.4%) had Ki67 >10% at wk 4, compared to 231 of the 815 (28.3%) who had BL Ki67 >15% and subsequent Ki67 >10% at wk 4. 2% of pts who remained on NET due to on-treatment Ki67 <10% had PD. Response and PEPI-0 rates by group will be reported.
Conclusion: ALTERNATE trial data support a model whereby levels of ER, PR and Ki67 at diagnosis can be used for the identification of postmenopausal pts with primary ER+/HER2- BC who are appropriate for NET. When baseline ER Allred scores are >6 and Ki67 ≤15%, there is a low likelihood of ET-resistant disease. When BL Ki67 is >15%, ET sensitivity is variable, and on-treatment biopsy for Ki67 may assist in triaging regarding NET appropriateness, particularly given the extremely low local PD rates seen in ALTERNATE when on-treatment Ki67 was <10%. Support: U10CA180821, U10CA180882, U24CA196171, UG1CA189856, U10CA180868 (NRG); NCI BIQSFP, BCRF, Genentech, AstraZeneca. https://acknowledgments.alliancefound.org; Clinical Trials.gov Identifier: NCT01953588
Table 1 Baseline levels of ER, PR, and Ki67 in Relation to Wk 4 Ki67 (N=1,085)BaselineWeek 4GroupNERAllred ScorePRAllred ScoreKi67Ki67 ≤10%N (%)Ki67 >10%N (%)1N=26<6≤15%0 (0%)2 (100%)9 (90)N=86 15%1 (12.5%)7 (87.5%)2AN=647 or 8<6≤15%61 (95.3%)3 (4.7%)90 (30.1)N=2357 or 8 15%148 (63%)87 (37%)2BN=466 or 7≥6≤15%42 (91.3%)4 (8.7%)51 (30.2)N=1236 or 7≥6>15%76 (61.8%)47 (38.2%)3N=1508≥6≤15%143 (95.3%)7 (4.7%)104 (17.1)N=4578≥6>15%360 (78.8%)97 (21.2%)
Citation Format: Matthew J Ellis, Vera Suman, A. Marilyn Leitch, Souzan Sanati, Kiran Vij, Gary W Unzeitig, Jeremy Hoog, Mark Watson, Olwen Hahn, Joseph Guenther, Abigail Caudle, Erika Crouch, Horacio Maluf, Mitch Dowsett, Amy Tiersten, Monica Mita, Wajeeha Razaq, Tina J Hieken, Yang Wang, Travis Dockter, Jo Anne Zujewski, Anna Weiss, Clifford Hudis, Eric P Winer, Kelly Hunt, Ann H Partridge, Cynthia X Ma, Lisa A Carey. Validation of a predictive model for potential response to neoadjuvant endocrine therapy (NET) in postmenopausal women with clinical stage II or III estrogen receptor positive (ER+) and HER2 negative (HER2-) breast cancer (BC): An ALTERNATE trial analysis (Alliance A011106) abstract. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PD2-10.
Abstract
Background: Ki67 values >10% 2-4 weeks (wks) after starting neoadjuvant ET (NET) indicates persistent cell proliferation, resistance to ET, and is associated with increased risk of ...recurrence. The ACOSOG Z1031 trial suggested that these tumors are also relatively chemotherapy (chemo) resistant with a low pathologic complete response (pCR) rate to NCT. The ALTERNATE trial (NCT01953588) is a randomized study of neoadjuvant anastrozole (ANA), fulvestrant (FUL), or ANA + FUL in postmenopausal patients (pt) with newly diagnosed clinical stage II or III ER+ (Allred score 6-8)/HER2- BC. Ki67 >10% at wk 4 or 12 after starting NET triggered triage to NCT of physician choice or weekly paclitaxel. Pts who refused protocol-directed therapy, were not candidates for NCT, or decided to undergo immediate surgery are being followed per protocol. Here we report the rates of pCR and residual cancer burden (RCB) following NCT for pts triaged to NCT due to Ki67 >10% at wk 4 or 12. Results: Of the 1,299 eligible pts randomized to receive ANA, FUL, or ANA + FUL, 286 (22%) had Ki67 >10% at wk 4 or 12. 168 of these 286 pts (58.7%) chose to switch to NCT, 32 went to surgery (11.2%), and 86 discontinued further protocol-directed therapy (30.1%). Among the 168 pts who underwent NCT, the presenting clinical T stages were cT2 (n=113; 67.26%), cT3 (n=47; 27.98%) and cT4 (n=8; 4.76%) and N stages were cN0 (n=82; 48.8%), cN1 (n=75; 44.6%), cN2/3 (n=9; 5.4%) and cNx (n=2; 1.2%). Central ER testing was performed on pre-treatment biopsies and confirmed ER Allred score 6-8 in 155 of 168 (92.2%) pts, with the rest being ER Allred score 4-5 (n=5; 3%), ER- (Allred score 0) (n=2; 1.2%), or not tested (n=6; 3.6%). Most (n=139; 82.7%) were ER+/PR+, while 17.3% (n=29) were ER+/PR-, and tumor grades were G1 (n=10; 6%), G2 (n=99; 58.9%), G3 (n=54; 32.1%), not reported (n=5; 3%). Baseline Ki67 levels prior to NET were >10% in 94% (n=158), ≤10% in 3% (n=5), and not done in 3% (n=5). NCT regimens administered included doxorubicin/cyclophosphamide (AC) followed by paclitaxel (T) (n=60; 35.71%); weekly paclitaxel (n=56; 33.33%), docetaxel/cyclophosphamide (TC) (n=33; 19.65%), other doxorubicin and/or taxane containing regimen (n=17; 10.12%), and cyclophosphamide/methotrexate/fluorouracil (CMF) (n=2; 1.19%). 35 (20.8%) pts did not complete planned course of NCT due to toxicity (n=27) or refusal (n=8). 154 NCT pts underwent surgery (mastectomy in 40.3%, and breast conserving surgery in 59.7%). The path ypT stages were Tis/0 (n=10; 6.5%), T1 (n=62; 40.3%), T2 (n=61; 39.6%), and T3/4 (n=21; 13.6%), and the ypN stages were N0 (n=66; 42.9%), N1 (n=57; 37%), N2/3 (n=30; 19.5%), and Nx (n=1; 0.6%). Among the 168 pts who started on NCT (intent to treat population), there were 8 pCRs (no invasive disease in the breast or lymph nodes) (4.8%; 95% CI: 2.1% to 9.2%). Residual Cancer Burden (RCB) categories include RCB 0 (n=8; 4.8%), RCB 1 (n=15; 8.9%), RCB 2 (n=82; 48.8%), RCB 3 (n=42; 25.0%), and not determined (n=21; 12.5%). Correlations of baseline pt and tumor characteristics with pathology response to NCT will also be presented. Conclusion: In pts with NET-resistant ER+/HER2- BC, salvage NCT is not likely to induce a complete or near complete response. More effective treatments are needed for this high-risk ER+/HER2- pt population. Support: U10CA180821, U10CA180882, U24CA196171, UG1CA189856, U10CA180868 (NRG); NCI BIQSFP, BCRF, Genentech, AstraZeneca. https://acknowledgments.alliancefound.org. Clinical Trials.gov Identifier: NCT01953588
Citation Format: Cynthia X Ma, Vera Suman, A. Marilyn Leitch, Souzan Sanati, Kiran Vij, Gary W Unzeitig, Jeremy Hoog, Mark Watson, Olwen Hahn, Joseph Guenther, Abigail Caudle, Erika Crouch, Horacio Maluf, Amy Tiersten, Monica Mita, Wajeeha Razaq, Tina J Hieken, Yang Wang, Travis Dockter, Jo Anne Zujewski, Anna Weiss, Kelly Hunt, Clifford Hudis, Eric P Winer, Matthew J Ellis, Lisa A Carey, Ann H Partridge. Neoadjuvant chemotherapy (NCT) response in postmenopausal women with clinical stage II or III estrogen receptor positive (ER+) and HER2 negative (HER2-) breast cancer (BC) resistant to endocrine therapy (ET) in the ALTERNATE trial (Alliance A011106) abstract. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr GS4-05.
Several phosphoinositide 3-kinase (PI3K) catalytic subunit inhibitors are currently in clinical trial. We therefore sought to examine relationships between pharmacologic inhibition and somatic ...mutations in PI3K catalytic subunits in estrogen receptor (ER)-positive breast cancer, in which these mutations are particularly common. RNA interference (RNAi) was used to determine the effect of selective inhibition of PI3K catalytic subunits, p110alpha and p110beta, in ER(+) breast cancer cells harboring either mutation (PIK3CA) or gene amplification (PIK3CB). p110alpha RNAi inhibited growth and promoted apoptosis in all tested ER(+) breast cancer cells under estrogen deprived-conditions, whereas p110beta RNAi only affected cells harboring PIK3CB amplification. Moreover, dual p110alpha/p110beta inhibition potentiated these effects. In addition, treatment with the clinical-grade PI3K catalytic subunit inhibitor BEZ235 also promoted apoptosis in ER(+) breast cancer cells. Importantly, estradiol suppressed apoptosis induced by both gene knockdowns and BEZ235 treatment. Our results suggest that PI3K inhibitors should target both p110alpha and p110beta catalytic subunits, whether wild-type or mutant, and be combined with endocrine therapy for maximal efficacy when treating ER(+) breast cancer.
Purpose
The recent publication of the ACOSOG Z1031 trial results demonstrated that Ki-67 proliferation marker-based neoadjuvant endocrine therapy response monitoring could be used for tailoring the ...use of adjuvant chemotherapy in ER+HER2-negative breast cancer patients. In this paper, we describe the development of the Ki-67 clinical trial assay used for this study.
Methods
Ki-67 assay assessment focused on reproducing a 2.7% Ki-67 cut-point (CP) required for calculating the Preoperative Endocrine Prognostic Index and a 10% CP for poor endocrine therapy response identification within the first month of neoadjuvant endocrine treatment. Image analysis was assessed to increase the efficiency of the scoring process. Clinical outcome concordance for two independent Ki-67 scores was the primary performance metric.
Results
Discordant scores led to a triage approach where cases with complex histological features that software algorithms could not resolve were flagged for visual point counting (17%). The final Ki-67 scoring approach was run on T1/2 N0 cases from the P024 and POL trials (
N
= 58). The percent positive agreement for the 2.7% CP was 87.5% (95% CI 61.7–98.5%); percent negative agreement 88.9% (95% CI: 65.3–98.6%). Minor discordance did not affect the ability to predict similar relapse-free outcomes (Log-Rank
P
= 0.044 and
P
= 0.055). The data for the 10% early triage CP in the POL trial were similar (
N
= 66), the percentage positive agreement was 100%, and percent negative agreement 93.55% (95% CI: 78.58–99.21%). The independent survival predictions were concordant (Log-rank
P
= 0.0001 and
P
= 0.01).
Conclusions
We have developed an efficient and reproducible Ki-67 scoring system that was approved by the Clinical Trials Evaluation Program for NCI-supported neoadjuvant endocrine therapy trials. Using the methodology described here, investigators are able to identify a subgroup of patients with ER+HER2-negative breast cancer that can be safely managed without the need of adjuvant chemotherapy.
Abstract only
504
Background: For PM patients (pts) with locally advanced ER+ HER2- BC, NET improves breast conservation surgery (BCS) rates, and modified preoperative endocrine prognostic index ...(mPEPI) 0, defined as pT1-2 pN0 Ki67< 2.7%, or pathologic complete response (pCR: no invasive disease in breast or lymph node) is associated with low risk of recurrence without adjuvant chemotherapy (CT). The ALTERNATE trial was initiated to assess if the endocrine-sensitive disease rate (ESDR: number of mPEPI 0 pts/number of eligible pts initiating NET) with fulvestrant (F) or F+anastrozole (A) is improved relative to A alone (reported here) and if the 5-year (yr) recurrence-free survival (RFS) rate for pts with mPEPI 0 on A alone without CT is ≥ 95% (awaits further follow-up). Methods: PM pts with clinical stage II/III ER+ HER2- BC were randomized 1:1:1 to 1 mg A po daily, 500 mg F IM every 4 week (wk)s after loading dose, or A+F for 6 months. Ki67 was tested centrally on biopsies acquired prior to NET, wk 4, wk 12 and at surgery. Pts with Ki67 >10% at wk 4 or 12 were recommended to go off protocol-directed ET and switch to CT. Pts with mPEPI 0 at surgery were recommended to continue assigned ET for 1.5 yrs followed by A for a total of 5 yrs ET (and not to receive CT). The primary endpoint of the neoadjuvant phase was ESDR. ESDR of each F arm was compared to that of the A alone arm. With 425 pts per arm, a one-tailed alpha = 0.025 chi-square test of two independent proportions has 84% power to detect an increase of ≥10% in ESDR for F or F+A compared to the A arm, assuming ESDR ≤30% in A. Results: 1362 pts (A 452; F 454; A+F 456) were enrolled Feb 2014 to Nov 2018. 63 pts were excluded (did not start NET). Of the remaining 1299 pts (A 434; F 431, A+F 434), 42% were cN1-3 and 73% were considered candidates for BCS. ESDR was 18.6% (95%CI: 15.1-22.7%) with A, 22.7% (95%CI: 18.9-27.0%) with F, and 20.5% (95%CI: 16.8-24.6%) with A+F. No significant difference in ESDR was found between A and F (p=0.15) or A and A+F (p=0.55). Among the 825 pts with wk 4 Ki67 < 10% who completed NET and surgery, ESDR and the BCS rate were 27.7% and 70.3% with A; 29.6% and 68.1% with F, and 26.8% and 69.9% with A+F, respectively. Conclusion: Neither F nor F+A significantly improved ESDR compared to A alone in PM pts with locally advanced ER+ HER2- BC. RFS data are awaited. Support: U10CA180821, U10CA180882, U24CA196171, https://acknowledgments.alliancefound.org ; NCI BIQSFP, BCRF, Genentech, AstraZeneca. Clinical trial information: NCT01953588 .
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