Bayesian Predictive Probability Research Articles

Bayesian Predictive Probability Based on a Bivariate Index Vector for Single-Arm Phase II Study With Binary Efficacy and Safety Endpoints.

In oncology, Phase II studies are crucial for clinical development plans as such studies identify potent agents with sufficient activity to continue development in the subsequent Phase III trials. Traditionally, Phase II studies are single-arm studies, with the primary endpoint being short-term treatment efficacy. However, drug safety is also an important consideration. In the context of such multiple-outcome designs, predictive probability-based Bayesian monitoring strategies have been developed to assess whether a clinical trial will provide enough evidence to continue with a Phase III study at the scheduled end of the trial. Therefore, we propose a new simple index vector to summarize the results that cannot be captured by existing strategies. Specifically, we define the worst and most promising situations for the potential effect of a treatment, then use the proposed index vector to measure the deviation between the two situations. Finally, simulation studies are performed to evaluate the operating characteristics of the design. The obtained results demonstrate that the proposed method makes appropriate interim go/no-go decisions.

Abstract PO1-14-07: Programme of mast cell subsets to potentiate breast cancer immunotherapy: from bed to bench to bed (the phase 2 platform RENAISSANCE trial)

Abstract Background: Immune checkpoint inhibitors (ICIs) have heralded a new era in breast cancer treatment; however, response rates remain limited, making precision immune-oncology a major unmet need. In addition to T cells, effective immune responses to ICIs rely on coordinated interactions between innate and adaptive immune cells. Mast cells are evolutionarily conserved, tissue-resident cells of importance to human health. Specific subsets of mast cells might be endowed with opposite roles in cancer treatment, yet the extent of mast cell heterogeneity and its clinical merit in immunotherapy remain undefined. Objective: We sought to comprehensively characterize mast cells in breast cancer, investigate their association with immunotherapy response with in-depth mechanistic insights, and identify actionable strategies to modulate mast cell functional states, thereby optimizing immunotherapy efficacy. Methods: We employed single-cell profiling on longitudinal breast cancer samples from three independent clinical trials (NCT04613674, NCT03197389 and GSE169246) to delineate mast cell heterogeneity in anti-PD-(L)1 therapy. By integrating multi-omic analyses, tissue characterization, preclinical experiments, transgenic mice, and high-throughput drug screening, we outlined the molecular features, underlying mechanisms, and clinical relevance of distinct mast cells to elicit ICI-responsive microenvironments. Subsequently, we launched RENAISSANCE (NCT05076682), a proof-of-concept, Bayesian adaptive, phase 2 platform trial, to evaluate the efficacy and safety of combining mast cell therapeutics with anti-PD-1 backbone therapy in metastatic triple-negative breast cancer (TNBC) patients who progressed after immunotherapy. The primary endpoint was the objective response rate (ORR) assessed using RECIST v1.1 criteria. Results: We identified a distinct population of mast cells termed antigen-presenting mast cells (APMCs), constituting approximately 30% of intratumoral mast cells and correlating with improved clinical benefit of anti-PD-(L)1 therapy in TNBC. APMCs displayed MHC-II and costimulatory molecules, and indicated the presence of tumor-reactive T cells and tertiary lymphoid structures. Using three immunocompetent mouse models, we confirmed the immunomodulatory capacity of APMCs in immunotherapy. Mechanistically, by employing Cpa3CreERT2Cd74fl/fl mice, we demonstrated that APMCs potentiate anti-PD-1 efficacy and antitumor T cell immunity through their antigen-presentation machinery. Interestingly, we identified cromolyn, an FDA-approved drug for allergy, as a potential therapeutic agent that elicited APMC-dependent CD8+ T cell cytotoxicity to synergize with anti-PD-1 therapy. Between February 2022 and March 2023, 10 patients with immunotherapy-refractory metastatic TNBC were enrolled to receive cromolyn plus camrelizumab backbone treatment. Given Bayesian predictive probability, this arm was “graduated” due to meeting the pre-specified efficacy boundary, with an ORR of 40.0% (4/10). The treatment was well tolerated with similar safety profiles of relevant drugs. Conclusions: Our findings provide crucial insights into the impact of mast cell heterogeneity on the clinical response to ICIs at a single-cell level, and pave the way for APMC-directed therapeutic interventions in cancer treatment. To our knowledge, this is the first prospective study in breast cancer of cromolyn plus anti-PD-1 backbone regimen after anti-PD-(L)1 immunotherapy failure, demonstrating significant antitumor activity and commendable tolerability. Consequently, we suggest a phase 3 randomized study to consolidate this finding, which might be an effective treatment in patients for whom there are few effective treatment options. Citation Format: Song-Yang Wu, Xi Jin, Yin Liu, Wen-Jia Zuo, Li Chen, Xiyu Liu, Lei Fan, Zhong-Hua Wang, Yan-Fei Liu, Yi-Zhou Jiang, Zhi-Ming Shao. Programme of mast cell subsets to potentiate breast cancer immunotherapy: from bed to bench to bed (the phase 2 platform RENAISSANCE trial) [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 PO1-14-07.

Atezolizumab and bevacizumab in combination with TACE for patients with BCLC B HCC.

TPS584 Background: The combination of atezolizumab and bevacizumab (AB) is an effective regimen for patients with advanced HCC1. Moving effective systemic therapy to earlier stages of HCC is a priority in improving outcomes. Assessing the safety of the combination of AB and TACE is essential to evaluating this regimen. Methods: This is an open-label, single arm pilot study. The primary objective of this study is to examine the safety and tolerability of AB with TACE. The secondary objectives are response rate, time to progression, overall survival, time to TACE progression (TTTP), and time to untaceable progression. Approximately 24 patients will be enrolled. AB will be given every 3 weeks (A: 1200 mg; 15 mg/kg) weeks and TACE will be planned for each patient to be completed in up to 4 treatments. B will be held for cycles that are within 4 weeks before or after each TACE. Imaging will be every 8 weeks for the first year, then every 12 weeks for the second year. Based on data from the GO30140 and the IMbrave 150 studies, we assume the rate of grade 3 or higher AEs is approximately 55% for AB and will likely be higher with the addition of TACE. Safety will be continuously monitored using the Bayesian Predictive Probability (PP) approach2. The PP that the rate of grade 3 or higher AEs is related to the combination is greater than 70% by the end of the trial based on toxicity data in the current stage will be continuously updated. Inclusion criteria includes patients over 18 years old with an ECOG PS of 0 or 1, no cirrhosis or Child-Pugh A cirrhosis, diagnosis of HCC by imaging or biopsy, and EGD within 6 months with no evidence of gastroesophageal varices with bleeding or high risk of bleeding unless treated. Patients are excluded if they are candidates for curative intent therapy, have had hepatic encephalopathy in the last 12 months, have occlusion of the hepatic artery or main portal vein, or have history of significant autoimmune disease. 1. Finn, Richard S., et al. New England Journal of Medicine 382.20 (2020): 1894-1905. 2 Lee J and Liu D. Clinical Trials. 2008; 5(2): 93-106. Clinical trial information: NCT05776875 .

Evaluating novel therapies and circulating tumor DNA (ctDNA) as a marker of response in curatively treated gastrointestinal cancers with microscopic residual disease.

TPS765 Background: ctDNA has emerged as a novel tool that can identify the earliest sign of relapse (MRD) after curative therapies with specificities of 93-100%, positive predictive values over 98%, and median lead times of 8-9 months before radiographic relapse. ctDNA has allowed us to identify a "new stage" of high-risk patients (pts) with no evidence of disease radiographically (rNED) and MRD who lack guideline-directed treatment (tx) strategies as, traditionally, they wait for radiographic progression of disease (POD) before starting therapies. Treating MRD is a promising strategy supported by observational studies where ctDNA clearance is linked with improved survival and on-tx ctDNA kinetics predict drug efficacy. We designed a pilot investigator-initiated trial to 1) determine the feasibility of using a surrogate marker, ctDNA, as a rapid signal for positive therapeutic activity and 2) obtain pilot data on the efficacy of a novel combination therapy (atezolizumab [A] + bevacizumab [B]) in eradicating MRD in previously curatively treated pts with GI cancers. Methods: We will enroll 20 pts with any-stage GI cancers divided over 4 cohorts (n=5 colorectal [CRC], n=5 hepatocellular/biliary tract carcinoma, n=5 gastric, n=5 pancreatic adenocarcinoma) who have a positive Signatera ctDNA test and rNED any time after completing standard curative-intent therapies. Pts are treated with A 1200 mg IV + B 15 mg/kg IV on day 1 of a 21-day cycle for up to 1 year with imaging every 12 weeks and serial ctDNA testing every 3 weeks. Co-primary endpoints are rates of pt enrollment in 12 months and rates of ctDNA responses at a 12-week landmark after tx initiation. Pts with ctDNA POD (ctDNA doubling on each of 2 sequential tests, any rate of rise in 3 sequential tests, or radiographic relapse) will stop while those with ctDNA complete response (CR; clearance on 2 sequential tests + ongoing rNED) or ctDNA partial/stable response (PR; not ctDNA CR or POD + ongoing rNED) will continue tx. Each cohort's Bayesian predictive probability of positive therapeutic activity will be calculated. If at least 60% of a cohort experiences ctDNA CR, it will be expanded by 5 pts. This scenario is equivalent to Simon's 2-stage Minimax design testing a null hypothesis of 20% CR vs. an alternative hypothesis of at least 60% CR at 5% alpha with 80% power. If at least 5/10 pts in an expanded cohort experience ctDNA CR, this will generate interest in developing a larger confirmatory trial to evaluate pt survival outcomes with A+B and ctDNA as a surrogate for survival. Secondary endpoints are toxicity and reasons for enrollment failure. Exploratory endpoints are associations between ctDNA conversion and disease-free survival, tumor whole exome sequencing data, and peripheral blood immune profiles collected at baseline and on tx. Enrollment began in Q1 2023. 4 pts are enrolled in the CRC cohort. Clinical trial information: NCT05482516 .

Bayesian predictive probability design: theory and practical application in a prospective study

In an experiment-based prospective study aiming to determine the efficiency of a treatment, the time by which it becomes clear whether a therapy is effective or not is critical. This applies specifically to clinical trials and refers to the same extent to both successful and futile therapies. This study seeks to answer the question when there is enough evidence allowing the trial to be finalised. The key is to find enough statistical signals, working on the smallest possible sample, to make a judgment whether to extend, continue or terminate the study. The Bayesian predictive design allows drawing conclusions about the prognosis of a study considering the actual results. The article provides a theoretical background and presents a practical perspective, addressing the statistical properties and technical aspects of conducting a trial based on a predictive design. Additionally, the sensitivity of the design to the choice of prior distribution is discussed.

HJKC3-007: Outcomes of Patients with Chronic Myeloid Leukemia in Chronic Phase Treated with Asciminib and Other Tyrosine Kinase Inhibitors in Routine Clinical Practice

Background and significance: There are typically high response rates to first line TKI therapies in chronic phase chronic myeloid leukemia (CP-CML). However, responses in later lines (second line and beyond) are diminished and highly dependent on the specific tyrosine kinase inhibitors (TKIs) used. Asciminib received FDA approval in October 2021 for the treatment of adult patients with Philadelphia chromosome-positive (Ph+) CML-CP who were previously treated with two or more TKIs, and in patients with Ph+ CML-CP with the T315I mutation. Our goal in this study is to evaluate the role of asciminib therapy for patients with CML beyond clinical studies, in routine clinical practice. Study Design and methods: Data for this study will be abstracted from the HJKC3 (H. Jean Khoury Cure CML Consortium) CML registry project (HJKC3-0005); the HJKC3 CML Registry is a collaborative academic multi-site registry. Patients will be consented to allow collection of both retrospective and prospective data for the HJKC3 CML Registry. The data forms and surveys will be built and managed through the Research Electronic Data Capture (REDCap), a secure web application managed by the Clinical & Translational Science Institute. Participating sites include members of the HJKC3 (curecml.org). This study will be an opportunity to evaluate asciminib usage in ‘real-world’ academic practices across the United States. This observational study will include cohorts of patients diagnosed with CP-CML previously treated with two or more tyrosine kinase inhibitors and/or receiving asciminib and/or those with a T315I mutation, not currently enrolled in a randomized controlled trial. The HJKC3 CML Registry intends to collect clinical and patient reported outcome (PRO) data. After obtaining patient consent, patients will be invited to complete PRO assessments. The study will attempt to collect PRO data regardless of disease or treatment status. PRO assessments will be primarily administered online, though study staff will offer alternatives (e.g., phone) for participants without internet access. Study subjects will be emailed a link to access a secure platform hosted by one of the study sites, Medical College of Wisconsin (MCW), using the REDCap platform. Study Objectives: The primary objective of the study is to describe characteristics of patients who were previously treated with two or more TKIs and treated with asciminib or with any other TKIs. The secondary objectives are to describe the clinical outcomes and PRO of those patients. Exploratory objectives include description of characteristics, treatment outcome and PRO for patients with T315I mutation. Statistical plan: The sample size of approximately 225 participants during the 5-year recruitment period is based on the available clinical expertise and ongoing recruitment data in the HJKC3 CML registry in lieu of statistical power analysis. We estimate that 150 patients in the HJKC3 CML registry will be treated with other TKI and 75 treated with asciminib. Among a total of 225 patients, we estimate that 75 patients with the T315I mutation will be enrolled in the registry. No formal statistical inference will be drawn to compare the outcomes between these two groups. Bayesian predictive probability (PP) will be utilized for the exploratory analysis of Major Molecular Response (MMR). Survival probabilities will be computed using the Kaplan-Meier method, and the p-values from the log-rank test will be provided. Different PRO domains of the patient's symptoms and functioning will be analyzed separately (e.g., depression separate from fatigue, separate from GI symptoms, etc.) since combining them into a summary score may dilute the effects of the individual (and not necessarily related) components and mask actual change. The main objective for the analyses of PRO data from the registry is to describe any differences by treatment type in patients treated with asciminib and other TKIs.

Adaptive designs in critical care trials: a simulation study

BackgroundAdaptive clinical trials are growing in popularity as they are more flexible, efficient and ethical than traditional fixed designs. However, notwithstanding their increased use in assessing treatments for COVID-19, their use in critical care trials remains limited. A better understanding of the relative benefits of various adaptive designs may increase their use and interpretation.MethodsUsing two large critical care trials (ADRENAL. ClinicalTrials.gov number, NCT01448109. Updated 12-12-2017; NICE-SUGAR. ClinicalTrials.gov number, NCT00220987. Updated 01-29-2009), we assessed the performance of three frequentist and two bayesian adaptive approaches. We retrospectively re-analysed the trials with one, two, four, and nine equally spaced interims. Using the original hypotheses, we conducted 10,000 simulations to derive error rates, probabilities of making an early correct and incorrect decision, expected sample size and treatment effect estimates under the null scenario (no treatment effect) and alternative scenario (a positive treatment effect). We used a logistic regression model with 90-day mortality as the outcome and the treatment arm as the covariate. The null hypothesis was tested using a two-sided significance level (α) at 0.05.ResultsAcross all approaches, increasing the number of interims led to a decreased expected sample size. Under the null scenario, group sequential approaches provided good control of the type-I error rate; however, the type I error rate inflation was an issue for the Bayesian approaches. The Bayesian Predictive Probability and O’Brien-Fleming approaches showed the highest probability of correctly stopping the trials (around 95%). Under the alternative scenario, the Bayesian approaches showed the highest overall probability of correctly stopping the ADRENAL trial for efficacy (around 91%), whereas the Haybittle-Peto approach achieved the greatest power for the NICE-SUGAR trial. Treatment effect estimates became increasingly underestimated as the number of interims increased.ConclusionsThis study confirms the right adaptive design can reach the same conclusion as a fixed design with a much-reduced sample size. The efficiency gain associated with an increased number of interims is highly relevant to late-phase critical care trials with large sample sizes and short follow-up times. Systematically exploring adaptive methods at the trial design stage will aid the choice of the most appropriate method.

Interim Analysis of DD3: A Phase IB/II Trial of Dose-Deescalated 3-Fraction SBRT for Centrally Located Lung Cancer

Prior studies suggested excessive toxicity for central lung tumors treated with 3-fraction stereotactic body radiation therapy (SBRT). This may be related to the high biologically equivalent dose assuming alpha/beta of 10 (BED) of 54 Gy in 3 fractions (BED = 151.2), as 50-60 Gy in 5 fractions (BED = 100.0-132.0) was well-tolerated in RTOG 0813. We initiated a prospective phase IB/II trial to test the hypothesis that a dose-deescalated regimen of 45 Gy in 3 fractions (BED 112.5) would be safe and efficacious in central lung tumors. We enrolled patients with primary or secondary lung tumors ≤5cm in a central but not ultra-central tumor location defined as within 2 cm of (but not abutting) tracheobronchial tree, esophagus, or heart. Patients were either medically inoperable or refused surgical intervention. Co-primary endpoints were safety and efficacy, defined as local control (LC). Secondary endpoints included lobar control, regional control (LRC), distant control (DC), progression-free survival (PFS), cancer-specific survival (CSS), and overall survival (OS). Organ-at-risk dose constraints were consistent with those of RTOG 0236. The Bayesian predictive probability approach was utilized for continuous monitoring after 10 patients were treated and have mature assessment of toxicity, after which interim analysis was planned. We recommended terminating the trial for safety if there was sufficient evidence that the rate of grade ≥3 was greater than 0.25 (predictive probability >0.80). As of the data cut-off date of 1/26/23, the trial was open for 34 months (including a nearly-immediate suspension due to the COVID-19 pandemic). A total of 17 patients have been treated on protocol with a median follow-up of 12 months. No grade ≥3 adverse events attributable to SBRT have occurred to date, though one patient died of unrelated cardiac arrhythmias 1 month after SBRT completion (Table 1). Maximum CTCAE grade 2 adverse events attributable to SBRT occurred in 17.6% of patients. The predictive probability of concluding unacceptably high toxicity rate by the end of the trial based on toxicity data in the current stage is 0.62%. To date, there have been 0 local recurrences, 1 regional recurrence without local recurrence (8 months after SBRT completion, successfully salvaged with definitive chemoradiotherapy without additional toxicities), and 1 distant recurrence without local recurrence (6 months after SBRT in a patient with lung metastasis from colon adenocarcinoma). Interim analysis of the DD3 trial suggests that for patients with central but not ultra-central lung tumors, an SBRT regimen of 45 Gy in 3 fractions warrants continued trial accrual and follow-up given no grade ≥3 toxicities or local recurrences in the early follow-up period among the first 17 patients enrolled.

Stochastic curtailment tests for phase II trial with time-to-event outcome using the concept of relative time in the case of non-proportional hazards

ABSTRACT As part of the drug development process, interim analysis is frequently used to design efficient phase II clinical trials. A stochastic curtailment framework is often deployed wherein a decision to continue or curtail the trial is taken at each interim look based on the likelihood of observing a positive or negative treatment effect if the trial were to continue to its anticipated end. Thus, curtailment can take place due to evidence of early efficacy or futility. Traditionally, in the case of time-to-event endpoints, interim monitoring is conducted in a two-arm clinical trial using the log-rank test, often with the assumption of proportional hazards. However, when this is violated, the log-rank test may not be appropriate, resulting in loss of power and subsequently inaccurate sample sizes. In this paper, we propose stochastic curtailment methods for two-arm phase II trial with the flexibility to allow non-proportional hazards. The proposed methods are built utilizing the concept of relative time assuming that the survival times in the two treatment arms follow two different Weibull distributions. Three methods – conditional power, predictive power and Bayesian predictive probability – are discussed along with corresponding sample size calculations. The monitoring strategy is discussed with a real-life example.

Sample size reestimation and Bayesian predictive probability for single-arm clinical trials with a time-to-event endpoint using Weibull distribution with unknown shape parameter

ABSTRACT This manuscript consists of two topics. Firstly, we explore the utility of internal pilot study (IPS) approach for reestimating sample size at an interim stage when a reliable estimate of the nuisance shape parameter of the Weibull distribution for modeling survival data is unavailable during the planning phase of a study. Although IPS approach can help rescue the study power, it is noted that the adjusted sample size can be as much as twice the initially planned sample size, which may put substantial practical constraints to continue the study. Secondly, we discuss Bayesian predictive probability for conducting interim analyses to obtain preliminary evidence of efficacy or futility of an experimental treatment warranting early termination of a clinical trial. In the context of single-arm clinical trials with time-to-event endpoints following Weibull distribution, we present the calculation of the Bayesian predictive probability when the shape parameter of the Weibull distribution is unknown. Based on the data accumulated at the interim, we propose two approaches which rely on the posterior mode or the entire posterior distribution of the shape parameter. To account for uncertainty in the shape parameter, it is recommended to incorporate its entire posterior distribution in our calculation.

Epistemic uncertainty in Bayesian predictive probabilities

ABSTRACT Bayesian predictive probabilities have become a ubiquitous tool for design and monitoring of clinical trials. The typical procedure is to average predictive probabilities over the prior or posterior distributions. In this paper, we highlight the limitations of relying solely on averaging, and propose the reporting of intervals or quantiles for the predictive probabilities. These intervals formalize the intuition that uncertainty decreases with more information. We present four different applications (Phase 1 dose escalation, early stopping for futility, sample size re-estimation, and assurance/probability of success) to demonstrate the practicality and generality of the proposed approach.

Subtyping-based platform guides precision medicine for heavily pretreated metastatic triple-negative breast cancer: The FUTURE phase II umbrella clinical trial

Triple-negative breast cancer (TNBC) is a heterogeneous disease and lacks effective treatment. Our previous study classified TNBCs into four subtypes with putative therapeutic targets. Here, we report the final results of FUTURE, a phase II umbrella trial designed to explore whether the subtyping-based strategy may improve the outcomes in metastatic TNBC patients. A total of 141 patients with a median of three previous lines of therapies in the metastatic setting were enrolled in seven parallel arms. Confirmed objective responses were achieved in 42 patients (29.8%; 95% confidence interval [CI], 22.4–38.1). The median values of progression-free survival and overall survival were 3.4 (95% CI: 2.7–4.2) and 10.7 (95% CI: 9.1–12.3) months, respectively. Given Bayesian predictive probability, efficacy boundaries were achieved in four arms. Furthermore, integrated genomic and clinicopathological profiling illustrated associations of clinical and genomic parameters with treatment efficacy, and the efficacy of novel antibody–drug conjugates was explored in preclinical TNBC models of subtypes for which treatment was futile. In general, the FUTURE strategy recruits patients efficiently and provides promising efficacy with manageable toxicities, outlining a direction for further clinical exploration.

Abstract OT3-27-01: Subtyping-based platform guides precision medicine for heavily pretreated metastatic triple-negative breast cancer: a multicenter, phase 2, umbrella, FUTURE trial

Abstract Background: Triple-negative breast cancer (TNBC) is a heterogeneous disease and lacks effective treatment. Our previous study classified TNBCs into four subtypes (luminal androgen receptor [LAR], immunomodulatory [IM], basal-like immune-suppressed [BLIS], mesenchymal-like [MES]) with distinct molecular features. We aimed to assess the efficacy and safety of molecular subtype-derived precision treatment in patients with heavily pretreated metastatic TNBC. Methods: This open-label, phase 2, umbrella trial included patients from four centers in China. Participants were women (aged ≥18 years) with histologically confirmed metastatic TNBC with disease progression after multiple lines of standard chemotherapy. Patients were enrolled into seven parallel arms according to their molecular subtypes: LAR with or without ERBB2 somatic mutation/amplification assigned to arm A (pyrotinib with capecitabine) and arm B (androgen inhibitor included therapy); IM assigned to arm C (anti-PD-1 antibody with nab-paclitaxel); BLIS with or without BRCA1/2 germline mutation assigned to arms D (PARP inhibitor included therapy) and E (anti-VEGFR included therapy); MES without or with PI3K-AKT mutation assigned to arms F (anti-VEGFR included therapy) and G (everolimus with nab-paclitaxel). Bayesian predictive probability was adopted to monitor each arm, which can be terminated independently according to a prespecified futility or efficacy boundary. This trial is registered with ClinicalTrials.gov, NCT03805399. Findings: Between October 18, 2018, and February 11, 2022, we enrolled 141 patients. All patients were heavily pretreated and resistant to six categories of the most common chemotherapeutic agents used in breast cancer treatment, with a median of 3 previous lines of therapies in the metastatic setting (Table 1 and 2). The median follow-up was 18.3 months (IQR 11.7-27.7). A confirmed objective response was achieved in 42 (29.8%, 95% CI 22.4-38.1) of the 141 patients. The median PFS was 3.4 months (95% CI 2.7-4.2), and the median OS was 10.7 months (95% CI 9.0-12.3) (Table 3). Arms A, C, E and G achieved efficacy boundaries, with 3 (75.0%) out of 4 patients in arm A, 20 (43.5%) out of 46 patients in arm C, 13 (28.3%) out of 46 patients in arm E, and 3 (33.3%) out of 9 patients in arm G achieving objective responses. Potential predictive biomarkers of efficacy in each arm were explored. Safety data were consistent with the known safety profiles of relevant drugs. Interpretation: We demonstrate the feasibility and clinical utility of a subtyping-based, genomic sequencing-guided strategy which allows the majority of heavily pretreated metastatic TNBCs to benefit from precision treatment. Most arms exhibit promising efficacy and manageable toxicities, providing subtyping schema to optimize personalized treatment. Table 1. The FUTURE trial schema. Patients are stratified into seven arms using the FUSCC 484-gene NGS panel testing and IHC subtyping. Abbreviations: mTNBC, metastatic triple-negative breast cancer; NGS, next-generation sequencing; IHC, immunohistochemistry; FUSCC, Fudan University Shanghai Cancer Center; LAR, luminal androgen receptor; IM, immunomodulatory; BLIS, basal-like immune-suppressed; MES, mesenchymal-like; n, number; AR, androgen receptor; PD-1, programmed cell death-1; PARPi, poly ADP-ribose polymerase inhibitor; VEGF, vascular endothelial growth factor; mTORi, mammalian target of rapamycin inhibitors. Table 2. Patient characteristics in the FUTURE trial. Table 3. Summary of treatment efficacy of TNBC in the FUTURE trial Citation Format: Zhi-Ming Shao, Zhong-Hua Wang, Yi-Zhou Jiang, Yin Liu, Xiu-Zhi Zhu, Yi Xiao, Song-Yang Wu, Wen-Jia Zuo, Qiang Yu, A-Yong Cao, Jun-Jie Li, Ke-Da Yu, Guang-Yu Liu, Jiong Wu, Tao Sun, Jiuwei Cui, Zheng Lv, Hui-Ping Li, Xiao-Yu Zhu. Subtyping-based platform guides precision medicine for heavily pretreated metastatic triple-negative breast cancer: a multicenter, phase 2, umbrella, FUTURE trial [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr OT3-27-01.

Abstract PD11-03: PD11-03 Comparison of a mono Atezolizumab window followed by Atezolizumab and chemotherapy with Atezolizumab and chemotherapy in triple negative breast cancer – an interim analysis of the adaptive randomized neoadjuvant trial NeoMono

Abstract Introduction: Improvement of systemic treatment of TNBC represents an unmet medical need. Targeted therapy of regulatory immune pathways has become an important option in the treatment of many malignant diseases including breast cancer. Neodjuvant trials combining chemotherapy and checkpoint inhibitors (KEYNOTE-522 and IMpassion031) have demonstrated a meaningful benefit regarding pathological complete remission (pCR) for the addition of PD-1- or PD-L1-inhibitors to chemotherapy in patients with TNBC. In the KEYNOTE-522 trial, the addition of an immune checkpoint inhibitor (ICI) to neoadjuvant chemotherapy also had a beneficial impact on event-free survival even in patients who did not achieve a pCR. Of note, in the neoadjuvant GeparNuevo trial only those patients with TNBC who received a 2-week checkpoint inhibitor monotherapy window before the start of neoadjuvant chemotherapy in combination with checkpoint inhibition, achieved a significant pCR benefit from the addition of the PD-1 inhibitor Durvalumab to neoadjuvant chemotherapy alone. Methods: NeoMono is a phase 2 randomized multicenter trial recruiting male and female patients with primary TNBC (defined as ER/PR < 10% and HER2 negative). Neoadjuvant treatment in Arm A and B consists of Atezolizumab 1200 mg every 3 weeks in addition to neoadjuvant chemotherapy (i.e., 12 x Carboplatin and Paclitaxel q1w followed by Epirubicin and Cyclophosphamide q3w). Combination therapy in arm A is preceded by an Atezolizumab monotherapy window (i.e., 840 mg Atezolizumab once two weeks prior to initiation of combination therapy). Study goals are to compare the efficacy of neoadjuvant chemotherapy with Atezolizumab with and without an Atezolizumab two-week monotherapy window (primary endpoint: pCR) and the identification of biomarkers predicting (early) response to or resistance against Atezolizumab. The extensive translational program of the neoMono trial aims at identifying these biomarkers on tumor and patient level through analysis of sequential tissue and liquid biopsies. The NeoMono statistical design adapts the idea of a proof-of-concept trial and uses Bayesian posterior and predictive probabilities for inference about the primary hypothesis. Up to four planned efficacy interim analyses provide decision points for early stopping for success or futility. The expected maximum number of patients to be recruited is 458. Results: The predefined number of 50 patients in each arm being evaluable for the primary endpoint pCR has been reached and the results of the first planned interim analysis will be presented at the meeting. Conclusion: The addition of an ICI to state of the art neoadjuvant chemotherapy has recently been established as a new standard of care in TNBC. NeoMono has the potential to answer the question if the beneficial effect of the ICI can be increased by a chemotherapy free ICI monotherapy window prior to a combination with neoadjuvant chemotherapy. Citation Format: Hans-Christian Kolberg, Johannes Schumacher, Ramona Erber, Michael Braun, Bernhard Heinrich, Oliver Hoffmann, Peter A. Fasching, Georg Kunz, Michael P. Lux, Christian Schem, Eva-Maria Grischke, Mustafa Deryal, Kristina Lübbe, Arndt Hartmann, Sabine Kasimir-Bauer, Cornelia Kolberg-Liedtke. PD11-03 Comparison of a mono Atezolizumab window followed by Atezolizumab and chemotherapy with Atezolizumab and chemotherapy in triple negative breast cancer – an interim analysis of the adaptive randomized neoadjuvant trial NeoMono [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr PD11-03.

Abstract PD11-01: PD11-01 Evaluation of the PD-1 Inhibitor Cemiplimab in early-stage, high-risk HER2-negative breast cancer: Results from the neoadjuvant I-SPY 2 TRIAL

Abstract Background: I-SPY2 is a multicenter, phase 2 trial using response-adaptive randomization within biomarker subtypes defined by hormone-receptor (HR), HER2, and MammaPrint (MP) status to evaluate novel agents as neoadjuvant therapy for high-risk breast cancer. The primary endpoint is pathologic complete response (pCR). Cemiplimab (Cemi) is a PD-1 inhibitor approved for the treatment of NSCLC, cutaneous basal, and squamous cell cancer. Here, we report current efficacy rates of Cemi in combination with paclitaxel followed by AC. Methods: Women with tumors ≥ 2.5cm were eligible for screening. Only HER2 negative (HER2-) patients were eligible for this treatment; HR positive (HR+) patients had to be MP high risk. Treatment included paclitaxel 80 mg/m2 IV weekly x 12 and Cemi 350 mg IV given q3weeks x 4, followed by doxorubicin/cyclophosphamide (AC) every 2 weeks x 4. The control arm was weekly paclitaxel x 12 followed by AC every 2-3 weeks x 4. All patients undergo serial MRI imaging; and imaging response (at 3 weeks, 12 weeks and prior to surgery) were used along with accumulating pCR data to continuously update and estimate pCR rates for trial arms. Analysis was modified intent to treat. Patients who switched to non-protocol therapy count as non-pCR. The goal is to identify (graduate) regimens with ≥85% Bayesian predictive probability of success (i.e. demonstrating superiority to control) in a future 300-patient phase 3 neoadjuvant trial with a pCR endpoint within responsive signatures. Cemi was eligible to graduate in 3 pre-defined signatures: HER2-, HR-HER2-, and HR+HER2-. To adapt to changing standard of care, we constructed “dynamic controls” comprising ‘best’ alternative therapies using I-SPY 2 and external data and estimated the probability of Cemi being superior to the dynamic control. Results: 60 HER2- patients (28 HR+ and 32 HR-) received Cemi arm treatment. The control group included 357 patients with HER2- tumors (201 HR+ and 156 HR-) enrolled since March 2010. Cemi graduated in HR-/HER2- signature. Estimated pCR rates (as of June 2022) are summarized in the table. Immune-related endocrine disorders include: hypothyroid (14.5%), adrenal insufficiency (10%), hyperthyroid (4.8%),) and thyroiditis (3.2%). Only one grade 3 adrenal insufficiency was observed. All immune related AE’s were manageable. Additional biomarker analyses are ongoing and will be presented at the meeting. Response predictive subtypes (Immune+ vs Immune-) and additional predictive biomarkers were assessed. Associations with pCR will be presented at SABCS. Conclusion: The I-SPY 2 study aims to assess the probability that investigational regimens will be successful in a phase 3 neoadjuvant trial. Anti-PD-1 therapy with Cemi resulted in a higher predicted pCR rate in HR-/HER2- 55 rate% disease compared to control at 29%. Immune-mediated AE’s were observed. This data is consistent with previously published data using check point inhibitors in early-stage HR-/HER2- breast cancer. Estimated pCR rates Citation Format: Erica Stringer-Reasor, Rebecca A. Shatsky, Jo Chien, Anne Wallace, Judy C. Boughey, Kathy S. Albain, Hyo S. Han, Rita Nanda, Claudine Isaacs, Kevin Kalinsky, Zahi Mitri, Amy S. Clark, Christos Vaklavas, Alexandra Thomas, Meghna S. Trivedi, Janice Lu, Smita Asare, Ruixiao Lu, Maria Pitsouni, Amy Wilson, Jane Perlmutter, Hope Rugo, Richard Schwab, W. Fraser Symmans, Nola M. Hylton, Laura Van ’t Veer, Douglas Yee, Angela DeMichele, Donald Berry, Laura J. Esserman, I-SPY Investigators. PD11-01 Evaluation of the PD-1 Inhibitor Cemiplimab in early-stage, high-risk HER2-negative breast cancer: Results from the neoadjuvant I-SPY 2 TRIAL [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr PD11-01.

Some Thoughts on the Use of Predictive Probability in Clinical Trials.

In this short note, we express our viewpoint regarding declaring study success based on Bayesian predictive probability of study success.

Bayesian and frequentist approaches to sequential monitoring for futility in oncology basket trials: A comparison of Simon's two-stage design and Bayesian predictive probability monitoring with information sharing across baskets.

This article discusses and compares statistical designs of basket trial, from both frequentist and Bayesian perspectives. Baskets trials are used in oncology to study interventions that are developed to target a specific feature (often genetic alteration or immune phenotype) that is observed across multiple tissue types and/or tumor histologies. Patient heterogeneity has become pivotal to the development of non-cytotoxic treatment strategies. Treatment targets are often rare and exist among several histologies, making prospective clinical inquiry challenging for individual tumor types. More generally, basket trials are a type of master protocol often used for label expansion. Master protocol is used to refer to designs that accommodates multiple targets, multiple treatments, or both within one overarching protocol. For the purpose of making sequential decisions about treatment futility, Simon’s two-stage design is often embedded within master protocols. In basket trials, this frequentist design is often applied to independent evaluations of tumor histologies and/or indications. In the tumor agnostic setting, rarer indications may fail to reach the sample size needed for even the first evaluation for futility. With recent innovations in Bayesian methods, it is possible to evaluate for futility with smaller sample sizes, even for rarer indications. Novel Bayesian methodology for a sequential basket trial design based on predictive probability is introduced. The Bayesian predictive probability designs allow interim analyses with any desired frequency, including continual assessments after each patient observed. The sequential design is compared with and without Bayesian methods for sharing information among a collection of discrete, and potentially non-exchangeable tumor types. Bayesian designs are compared with Simon’s two-stage minimax design.

Abstract OT2-29-01: neoMono - An adaptive randomized neoadjuvant two arm trial in patients with TNBC comparing a mono atezolizumab window followed by atezolizumab and chemotherapy with atezolizumab and chemotherapy

Abstract Background: Improvement of systemic treatment of TNBC represents an unmet medical need. Recently, targeted therapy of regulatory immune pathways has become an important option in the treatment of numerous malignancies including breast cancer. Neoadjuvant trials combining chemotherapy and checkpoint inhibitors (KEYNOTE-522 and IMPASSION031) have demonstrated a meaningful benefit regarding pathological complete remission (pCR) and event-free survival (EFS) for the addition of PD-1- and PD-L1-inhibitors to chemotherapy among patients with TNBC, respectively. In addition, initial analyzes have presented promising results regarding event-free survival. In the neoadjuvant GeparNuevo trial only a subgroup of patients with TNBC, receiving a 2-week checkpoint inhibitor monotherapy window before the start of neoadjuvant chemotherapy in combination with checkpoint inhibition, achieved a pCR benefit as compared to patients treated with neoadjuvant chemotherapy alone. Trial Design: NeoMono is a phase 2 randomized multicenter trial recruiting male and female patients with primary TNBC (defined as ER/PR < 10% and HER2 negative). Neoadjuvant treatment in Arm A and B consists of Atezolizumab 1200 mg every 3 weeks in addition to neoadjuvant chemotherapy (i.e. 12 x Carboplatin and Paclitaxel q1w followed by Epirubicin and Cyclophosphamide q3w) In Arm A this therapy is preceded by Atezolizumab 840 mg q2w (Atezolizumab mono window). Study goals are the comparison of efficacy and safety of neoadjuvant chemotherapy with Atezolizumab with and without Atezolizumab two-week window (primary endpoint: pCR) and the identification of biomarkers predicting (early) response to or resistance against Atezolizumab. The broad translational program of the neoMono trial aims at identifying these biomarkers on tumor and patient level. The neoMono statistical design adapts the idea of a proof-of-concept trial and uses Bayesian posterior and predictive probabilities for inference about the primary hypothesis. Up to four planned efficacy interim analyses provide decision points for early stopping for success or futility. The expected maximum number of patients to be recruited is 458. Citation Format: Cornelia Kolberg-Liedtke, Johannes Schumacher, Ramona Erber, Michael Braun, Bernhard Heinrich, Oliver Hoffmann, Peter Fasching, Helmut Forstbauer, Anke Kleine-Tebbe, Georg Kunz, Michael Lux, Joachim Rom, Christian Schem, Nicole Stahl, Arndt Hartmann, Sabine Kasimir-Bauer, Hans-Christian Kolberg. neoMono - An adaptive randomized neoadjuvant two arm trial in patients with TNBC comparing a mono atezolizumab window followed by atezolizumab and chemotherapy with atezolizumab and chemotherapy [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 OT2-29-01.

Abstract PD8-07: Evaluation of Tucatinib + (Paclitaxel + Pertuzumab + Trastuzumab) followed by AC in high-risk HER2 positive (HER2+) stage II/III breast cancer: Results from the I-SPY 2 TRIAL

Abstract Background: I-SPY 2 is a multicenter, phase 2 trial using response-adaptive randomization within molecular subtypes defined by receptor status and MammaPrint (MP) risk to evaluate novel agents as neoadjuvant therapy for women with high-risk breast cancer. Tucatinib is a potent HER2 (ErbB2) tyrosine kinase inhibitor, selective for HER2 vs. epidermal growth factor receptor (EGFR) and is active vs. brain metastases. Safety and efficacy of tucatinib combined with paclitaxel, pertuzumab, and trastuzumab are unknown and were tested in a planned 10 patient (pt) safety run-in of the I-SPY 2 trial. Methods: Women with tumors ≥ 2.5cm were eligible for screening. Only pts with tumors that were HER2+ by FISH were eligible for this treatment. Treatment included tucatinib (max dose 300 mg) BID for 12 weeks with weekly paclitaxel 80 mg/m2 and trastuzumab (2 mg/kg weekly following loading), and pertuzumab (420 mg every 3 weeks following loading), followed by doxorubicin/cyclophosphamide (AC) every 2 weeks x 4. The control arm was weekly paclitaxel and trastuzumab with pertuzumab for 12 weeks followed by AC every 2 weeks x 4. All pts undergo serial MR imaging and response at 3 & 12 weeks is combined with real time pCR data to estimate, and continuously update, the predicted pCR rate for each trial arm. The goal of the trial is to identify/graduate regimens with ≥85.% Bayesian predictive probability of success (i.e. demonstrating superiority to control) in a future 300-patient phase 3 neoadjuvant trial with a pCR endpoint. This run-in arm was conducted to determine safety of combining tucatinib with paclitaxel/trastuzumab/pertuzumab, monitoring special adverse events of interest including LFT elevations and gastrointestinal toxicities.Methods: The I-SPY 2 methods have been previously published. Results: 20 pts were evaluable in tucatinib treatment arm. The control arm included 329 historical controls enrolled since April 2010. The initial tucatinib dose was 300 mg BID. After enrollment of the first 8 pts, there were 3 pts with grade 3 LFT elevations, 2 pts with grade 2/3 diarrhea, 1 pt with grade 2 neutropenia, and 1 pt with grade 3 nausea. After this safety review, the tucatinib dose was lowered to 250 mg BID. Among 5 additional pts enrolled, 3 developed grade 2/3 LFT abnormalities. The protocol was then modified to tucatinib 150 mg BID days 1-28 and then 250 mg BID days 29-84; 7 pts were treated. Safety data were reviewed after 20 pts were enrolled; the arm was then suspended due to similar LFT elevations regardless of tucatinib dose reduction or schedule. 7 of 20 pts (35%) had reversible Grade 3 or higher ALT/AST elevation (Table). No pt met criteria for Hy’s Law. In terms of efficacy, 12 of 14 evaluable pts had > 80% reduction of tumor volume by 12 weeks, measured by MRI assessment of functional tumor volume (FTV). Conclusion: The goal of the run-in arm was to determine the safety of adding tucatinib to the combination of paclitaxel/trastuzumab/pertuzumab. The addition of tucatinib resulted in unacceptable but reversible LFT elevations despite tucatinib dose reduction. Tucatinib containing therapy resulted in >80% decline in tumor volume at 12 weeks in 86% of pts. Tucatinib showed a high level of activity when combined with paclitaxel/trastuzumab/pertuzumab, but the combination is not feasible. Table: Number of pts with grade 2, 3, and 4 LFT elevations by treatment schedule (highest grade per patient per event, ALT or Treatment scheduleGrade 2 LFT elevationGrade 3 LFT elevationGrade 4 LFT elevationTucatinib 300 mg BID030Tucatinib 250 mg BID210Tucatinib 150 mg BID days 1-28 followed by 250 mg BID days 29 to 84112 Citation Format: David A Potter, Erin Roesch, Christina Yau, Ruixiao Lu, Denise Wolf, Susan Samson, Debra Stafford, Kathy S Albain, Claudine Isaacs, Meghana Trivedi, Douglas Yee, Judy Boughey, Alexandra Thomas, A. Jo Chien, Nola Hylton, Wen Li, Angela DeMichele, Jane Perlmutter, W. Fraser Symmans, Dawn L Hershman, Michelle Melisko, Laura J van 't Veer, Amy Wilson, Smita M Asare, Donald A Berry, Richard Schwab, Hope S Rugo, Laura J Esserman. Evaluation of Tucatinib + (Paclitaxel + Pertuzumab + Trastuzumab) followed by AC in high-risk HER2 positive (HER2+) stage II/III breast cancer: Results from the I-SPY 2 TRIAL [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 PD8-07.

Abstract PD1-10: Evaluation of SGN-LIV1a followed by AC in high-risk HER2 negative stage II/III breast cancer: Results from the I-SPY 2 TRIAL

Abstract Background: I-SPY 2 is a multicenter, phase 2 trial using response-adaptive randomization within molecular subtypes defined by receptor status and MammaPrint (MP) risk to evaluate novel agents as neoadjuvant therapy for women with high-risk stage II/III breast cancer. The primary endpoint is pathologic complete response (pCR, ypT0/Tis ypN0). SGN-LIV1A is an investigational antibody drug conjugate consisting of an antibody to LIV1A, a zinc transporter highly prevalent in breast cancer, and a highly potent microtubule inhibitor, monomethyl auristatin E. Retrospective IHC analysis of LIV1A expression levels amongst tumor samples from 100 previous ISPY-2 patients showed 88% of breast tumor samples with moderate to high expression of LIV1A (Yau, C. et al SABCS 2018).Methods: Women with tumors ≥ 2.5cm were eligible for screening. Only HER2 negative (HER2-) patients were eligible for this treatment, hormone-receptor positive (HR+) patients had to have MP high molecular profile. Treatment included SGN-LIV1A 2.5 mg/kg (max dose 250 mg) every 3 weeks x 4, followed by doxorubicin/cyclophosphamide (AC) every 2-3 weeks x 4. The control arm was weekly paclitaxel x 12 followed by AC every 2-3 weeks x 4. All patients undergo serial MR imaging where response at 3 & 12 weeks combined with accumulating pCR data are used to estimate, and continuously update, predicted pCR rate for the trial arm. Analysis set was modified intention to treat with patients who switched to non-protocol therapy counted as non-pCR and not as their pCR status at time of surgery. The goal is to identify/graduate regimens with ≥85% Bayesian predictive probability of success (i.e. demonstrating superiority to control) in a future 300-patient phase 3 neoadjuvant trial with a pCR endpoint within signatures defined by HR & HER2 status & MP result. This investigational arm was eligible for graduation in 3 of 10 pre-defined signatures: HER2-, HR+HER2- and HR-HER2-. Regimens may also leave the trial for futility (< 10% probability of success), maximum sample size accrual (10% < probability of success <85%), maximum time in trial (2 years) or for safety as recommended by the independent DSMB. Results: Sixty patients were randomized and evaluable to SGN-LIV1A. The study arm was stopped due to reaching the predetermined time limit for patient accrual of 2 yrs. Final estimated pCR rates are below. The estimated pCR rates were similar between the SGN-LIV1A and control arms for any tumor subtype. Preliminary safety events for SGN-LIV1A include increased rates of transaminitis and hyperglycemia and reduced rates of peripheral neuropathy compared to control. One patient was removed from the analysis as she was determined to have angiosarcoma of the breast. Notably, this patient had a dramatic early response and subsequent pCR to SGN-LIV1A treatment. Conclusion: The value of I-SPY 2 is to give insight about the performance of an investigational agent’s likelihood of achieving pCR. SGN-LIV1A delivered every 3 weeks was comparable to paclitaxel for the primary endpoint of pCR in I-SPY2 and may have a similar side effect profile, however, with less peripheral neuropathy. Clinical trials evaluating weekly dosing of SGN-LIV1A are ongoing. A trial of SGN-LIV1A in the treatment of angiosarcoma is under consideration at this time. Final Estimated pCR Rates and Predictive ProbabilitiesEstimated pCR rate(95% prob interval)SignatureSGN-LIV1AControlProbability SGNLIV1A Superior to ControlPredictive Probability of Success in Phase 3HER2-0.16 (0.08-0.24) N= 600.20 (0.16-0.25) N= 3270.180.02HR-/HER2-0.25 (0.12-0.37) N=360.28 (0.21-0.35) N=1460.310.06HR+/HER2-0.09 (0-0.18) N=240.14 (0.09-0.19) N=1810.150.03 Citation Format: Heather Beckwith, Richard Schwab, Christina Yau, Erica Stringer-Reasor, Shi Wei, A. Jo Chien, Kathy S Albain, Kevin Kalinsky, Anne Wallace, Anthony Elias, Douglas Yee, Amy S Clark, Judy C Boughey, Heather Han, Rita Nanda, Claudine Isaacs, Zahi Mitri, Julie E Lang, Alexandra Thomas, Tara Sanft, Angela DeMichele, Jane Perlmutter, Hope S Rugo, Nola M Hylton, W. Fraser Symmans, Michelle E Melisko, Laura J van't Veer, I-SPY 2 Consortium, Amy Wilson, Smita M Asare, Ashish Sanil, Donald A Berry, Laura J Esserman. Evaluation of SGN-LIV1a followed by AC in high-risk HER2 negative stage II/III breast cancer: Results from the I-SPY 2 TRIAL [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 PD1-10.