Evidence Of Disease Progression Research Articles

Abstract PO4-17-02: A multicenter, prospective, observational study of patients receiving trastuzumab deruxtecan for the treatment of HER2-positive and HER2-low unresectable and/or metastatic breast cancer: DESTINY-Breast-RESPOND

Abstract Background: Approximately 20% of breast cancer (BC) cases are human epidermal growth factor receptor 2-positive (HER2+; immunohistochemistry [IHC] 3+, IHC 2+/in-situ hybridization [ISH]+), and up to ~50% of patients with primary or metastatic BC (mBC) have HER2-low tumors (IHC 1+, IHC 2+/ISH−), a new therapeutically targetable subset of BC. Trastuzumab deruxtecan (T-DXd) is a HER2-directed antibody-drug conjugate approved in the USA, EU, and other countries for the treatment of adult patients with unresectable or metastatic HER2+ BC who have received a prior anti-HER2-based regimen, or with unresectable or metastatic HER2-low BC who have received a prior chemotherapy (CTx) in the metastatic setting or developed disease recurrence during or within 6 months of completing adjuvant CTx. Approvals followed positive results from the DESTINY-Breast03 and DESTINY-Breast04 clinical trials. In DESTINY-Breast03, T-DXd improved median progression-free survival (mPFS) compared with trastuzumab emtansine (28.8 vs 6.8 months, respectively; P< 0.0001) in previously treated (prior trastuzumab and taxane) patients with HER2+ mBC. In DESTINY-Breast04, T-DXd significantly improved mPFS vs physician’s choice of CTx (9.9 vs 5.1 months, respectively; P< 0.001) in all randomized patients with HER2-low mBC who were previously treated with one or two lines of CTx. Alongside these efficacy benefits, T-DXd has demonstrated an acceptable and generally manageable safety profile. To optimize care and maximize treatment benefit, insights into real-world T-DXd use and safety events of interest, including patient management and experience, are needed. This study aims to describe the effectiveness and tolerability of T-DXd in patients with HER2+ or HER2-low unresectable and/or mBC in a real-world setting. Trial design: DESTINY-Breast-RESPOND (NCT05592483) is a multicenter (120 sites planned as of June 2023), multi-country (HER2+ cohort: several regions globally; HER2-low cohort: North America only), prospective, observational study characterizing real-world clinical use, effectiveness, tolerability, and patient experience among adults who initiated T-DXd monotherapy, per standard of care, for HER2+ (second line or earlier) and HER2-low unresectable and/or mBC (T-DXd not provided by study sponsor). The decision to initiate T-DXd will be made by the physician prior to, and independent from, participation in this study. Approximately 750 patients with HER2+ and 250 patients with HER2-low disease will be enrolled. Patients must have received prior treatment with a trastuzumab-containing regimen in the metastatic setting or have evidence of disease progression within 6 months of neoadjuvant or adjuvant treatment (HER2+ cohort), or prior CTx in the metastatic setting or have evidence of disease progression within 6 months of adjuvant CTx (HER2-low cohort). Data will be collected via chart abstraction, patient-reported outcome questionnaires on tolerability and safety (PGI-TT, NCI PRO-CTCAE, and EORTC IL19), and a daily patient nausea/vomiting symptom diary. Endpoints will be analyzed separately for HER2+ and HER2-low cohorts. The primary endpoint of interest is time to next treatment from T-DXd initiation, a measure of real-world effectiveness. Other important endpoints include treatment patterns, safety events of interest (nausea/vomiting, fatigue, alopecia, interstitial lung disease/pneumonitis, left ventricular ejection fraction decrease) and their management, time to T-DXd discontinuation, and patient-reported tolerability. Patients will be observed until end of study (~60% of patients receive subsequent treatment or have died), withdrawal from study, or loss to follow up, whichever occurs first. Citation Format: Joyce O'Shaughnessy, Reva Basho, Maryam Lustberg, Gary H Lyman, Manoj Prahladan, Gareth D. James, Della Varghese, Flavia Lujan, Hans Tesch. A multicenter, prospective, observational study of patients receiving trastuzumab deruxtecan for the treatment of HER2-positive and HER2-low unresectable and/or metastatic breast cancer: DESTINY-Breast-RESPOND [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 PO4-17-02.

Abstract PO1-19-09: Integrating gene signatures to guide HR+ MBC therapy in a diverse cohort (INSIGHT)

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 PO2-20-01: The STOP-HER2 Trial: A Phase 2 Study of Stopping Trastuzumab - Outcomes in Patients with HER2+ Metastatic Breast Cancer (TBCRC 062)

Abstract BACKGROUND: Anti-HER2 therapies have transformed the trajectory for patients with HER2-positive (HER2+) MBC. A subset of patients with HER2+ MBC do exceptionally well and remain on maintenance anti-HER2 therapy for many years. However, current therapy is non-curative and patients are treated indefinitely. While these therapies often are well-tolerated, they may cause significant toxicities, are expensive, and typically require frequent infusion and provider visits. Case reports and retrospective series demonstrate that some patients may do well after stopping anti-HER2 treatment. We currently lack prospective data on the likelihood of clinical impact of successful treatment discontinuation, outcomes among patients who progress and restart HER2-directed therapy, and tools to predict who may safely stop therapy. In this study, we will enroll pts with an exceptional response to anti-HER2 therapy. Pts may elect to either continue or stop anti-HER2 therapy and will be followed clinically and radiographically on a protocol-specified schedule. Considering the central role of patients in choosing the study intervention arm, and the unique nature of stopping therapy as a treatment intervention, patient advocates have been deeply involved in the study design to ensure patient concerns are being heard and addressed. We will retrospectively assess minimal residual disease (MRD), measured in plasma, as a biomarker of ongoing response, in a step toward shifting the treatment paradigm for pts with HER2+ MBC. METHODS: STOP-HER2 is a prospective, non-randomized, phase II, multicenter study of either continuation (cohort 1) or cessation (cohort 2) of anti-HER2 therapy in exceptional responders with HER2+ MBC. Eligible patients must have biopsy-proven HER2+ MBC by ASCO/CAP guidelines and must have been receiving first-line anti-HER2 therapy for MBC for at least 3 years without evidence of progressive disease (PD) as determined by the treating investigator. Patients with prior brain-only PD or oligo-PD outside the brain are eligible at least 2 years after local treatment to the central nervous system (CNS) and in absence of subsequent PD. Up to fifty-two participants will be enrolled into cohort 2, and an additional thirty participants enrolled into the cohort 1, at 10 US sites within the Translational Breast Cancer Research Consortium. Co-primary endpoints are the 1-year progression-free survival (PFS) in cohorts 2 and 1, separately. Secondary endpoints include the clinical benefit rate upon re-initiation of anti-HER2 therapy for patients in cohort 2 experiencing PD after treatment discontinuation; and 3-year overall survival in both cohorts. Correlative endpoints include MRD status at baseline and the correlation between MRD dynamics and outcomes. Patient-reported outcomes will be collected and analyzed, including quality of life, illness intrusiveness, financial toxicity, anxiety, and decision regret. The study will use a two-stage design to assess the primary objective of estimating the rate of participants who are free of progression at one year after discontinuing anti-HER2 therapy. If 50% or less are free of progression at one year, stopping HER2 therapy would not be considered a viable treatment plan (null hypothesis). The study is designed to have 80% power to reject the null hypothesis at the 10% type I error rate when 68% of exceptional responders are free of progression at one year after stopping HER2 therapy. STOP-HER2 began enrollment in Q2 2023 (NCT05721248). Citation Format: Heather Parsons, Kathryn Ruddy, Stefania Morganti, Karen Smith, Victoria Attaya, Eliza Kallfelz, Michelle DeMeo, Jamie LaScala, Shirley Mertz, Teri Pollastro, Patricia Spears, Adam Brufsky, Chau Dang, Susan Dent, Ahmed Elkhanany, WIlliam Gwin, Ciara O'Sullivan, Kathy Miller, Sara Nunnery, Elaine Walsh, Anna Maria Storniolo, Sara Tolaney, Nabihah Tayob, Antonio Wolff, Eric Winer, Mothaffar Rimawi, Ian Krop, Nancy Lin. The STOP-HER2 Trial: A Phase 2 Study of Stopping Trastuzumab - Outcomes in Patients with HER2+ Metastatic Breast Cancer (TBCRC 062) [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 PO2-20-01.

Abstract PO2-04-01: Predictors of exceptional response to first line HER2-targeted therapy for metastatic breast cancer

Abstract Background HER2-targeted therapies have transformed the trajectory of HER2-positive (HER2+) metastatic breast cancer (MBC), with a subgroup of responders remaining on first line (1L) therapy for many years (yrs). Despite these promising outcomes, the paradigm remains palliative, with some patients (pts) receiving therapy indefinitely. Opportunities to interrupt therapy are controversial and anecdotal in the setting of a limited understanding of long-term responders and lack of predictive biomarkers. Methods We identified prevalent pts with HER2+ MBC seen and consented at Dana-Farber Cancer Institute between 2010 and 2023, regardless of the original date of MBC diagnosis. Exceptional responders (ExRes) were pts without evidence of progressive disease (PD) 3 yrs from initiation of 1L therapy for MBC. Conventional responders (ConRes) were pts who experienced PD within 3 yrs of 1L treatment initiation. We compared clinicopathological characteristics and treatment patterns between ExRes and ConRes using Chi-square or Wilcoxon test. We analyzed median time to treatment switch due to PD (TTS-PD) – i.e., time from metastatic diagnosis to 1L treatment end due to PD - and overall survival, via the Kaplan-Meier method and with a landmark analysis at year 3 (Y3). Our primary aim was to identify predictors of exceptional response to 1L anti-HER2 therapy. Results Of 635 pts with HER2+ MBC, we identified 147 ExRes and 370 ConRes and excluded 118 pts due to follow up ≤ 3 yrs and no PD events. Median follow up was 7.1 yrs (IQR 5.5-11.0) for ExRes and 7.1 yrs (IQR 4.0-11.4) for ConRes. Median age at MBC diagnosis was 50.7 yrs (range 21.9-91.9) for ExRes and 49.8 yrs (26.9-82.3) for ConRes. ExRes presented more often with de novo MBC than ConRes (52.1 vs 30.6%, p< 0.0001). On metastatic samples, more ExRes than ConRes had HER2 3+ tumors by immunohistochemistry (IHC) (93.7 vs 81.0%, p=0.002), whereas the proportion of ER-positive disease was similar between the two groups (45.6 vs 53.4%, p=0.1). Most pts received (neo)adjuvant anti-HER2 agents in both groups (62.5 vs 72.7%, p=0.1). More ExRes than ConRes (55.8 vs 42.7% p=0.007) received 1L chemotherapy (CT) plus trastuzumab (H)/pertuzumab (P). Alternative 1L treatments were CT plus H (26.5 vs 25.7%), H +/- P +/- endocrine therapy (8.2 vs 10.5%), T-DM1 (2 vs 9.2%), tyrosine kinase inhibitors-based regimens (7.5 vs 10.8%). For pts with recurrent MBC, disease-free interval was longer for ExRes than ConRes (median 4.7 vs 3.4 yrs, p=0.01). Visceral involvement at MBC relapse was similar for ExRes and ConRes (78.2 vs 77.8%, p=0.9). Brain metastases at any timepoint were less frequent among ExRes than ConRes (42.9 vs 55.1%, p=0.01). Among ExRes, 70 (47.6%) pts experienced PD after Y3, with a median TTS-PD of 4.6 (4.1-5.1) yrs. In a landmark analysis at Y3, the 2-year TTS-PD was 68.5% (95% CI: 59.8%-75.7%) (5 yrs from treatment start), and 4-year overall survival was 86.5% (95% CI: 78.1%-91.9%) (7 yrs from treatment start). ConRes received a median of 5 (1-19) treatment regimens for MBC, with a median 1L TTS-PD of 12 (10.8-13) mo. A total of 89 (60.5%) ExRes and 214 (57.8%) ConRes underwent tumor sequencing. Data comparing genomic features between ExRes and ConRes will be presented. Conclusions In this prospective cohort, 28% of pts with HER2+ MBC had exceptional response to 1L anti-HER2 therapy. Consistent with prior data, ExRes present more frequently with de novo disease and HER2 IHC 3+ tumors. In our cohort, ExRes had a median follow-up of 7.1 years and 52.4% never experienced PD. Although a significant proportion of pts with HER2+ MBC derive long-term benefit from anti-HER2 therapy, the treatment paradigm remains palliative, and it is unknown whether biomarkers may reliably predict exceptional response and guide future treatment. Ongoing work will explore whether genomic features vary between ExRes and ConRes. Citation Format: Stefania Morganti, Tianyu Li, Katheryn Santos, Melissa Hughes, Nolan Priedigkeit, Yvonne Li, Marla Lipsyc-Sharf, Gregory Kirkner, Janet Files, Julie Kasparian, Elizabeth Grant, Gunjan Gupta, Giuseppe Curigliano, Sara Tolaney, Andrew Cherniack, Nabihah Tayob, Nancy Lin, Heather Parsons. Predictors of exceptional response to first line HER2-targeted therapy for metastatic breast cancer [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 PO2-04-01.

When less is more: Updates in active surveillance and watchful waiting in the management of prostate cancer.

Prostate cancer is the second most common cancer among men globally. A range of management options are available for prostate cancer, including surgery, radiation therapy, hormone therapy, chemotherapy, or surveillance. Conservative strategies include active surveillance and watchful waiting, which differ in their intent. We provide a targeted instructive management algorithm for improving understanding of conservative strategies inprostate cancer. Active surveillance involves close monitoring with curative intent when there is evidence of disease progression. Incontrast, watchful waiting is palliative in intent and focuses on delaying treatment until symptoms or complications develop. Conservative approaches have demonstrated similar long-term oncological outcomes toradical treatment, while reducing harm from overtreatment, and maintaining quality of life by avoiding potential side effects such as urinary incontinence and erectile dysfunction. The decision to employ a conservative approach is determined by both patient and disease factors. Conservative management strategies play a vital role in the management of prostate cancer.

Pseudoprogression in a patient with metastatic melanoma treated with PD-1 and LAG-3 inhibition.

Pseudoprogression encapsulates a process of temporary radiographic growth followed by subsequent regression of metastatic melanoma lesions in response to immune checkpoint blockade (ICB), such as the combination of anti-programmed cell death protein 1 (PD-1) and anticytotoxic T-lymphocyte-associated antigen 4 therapy. This occurs in approximately 5-10% of ICB-treated patients, but has not yet been described in the context of novel combination therapies. Here, we report a case of an 89-year-old patient with metastatic melanoma to the liver, lung and lymph nodes, who underwent treatment with Opdualag (combining anti-PD-1 nivolumab and anti-lymphocyte-activation gene 3 relatlimab ICBs), and developed pseudoprogression after two cycles of therapy. The patient experienced a radiographic increase in liver metastatic lesion size, but was found to have a subsequent reduction in these lesions. The patient has been on therapy for 18 months without evidence of disease progression and continues to be clinically well-appearing.

Abstract CT195: First-in-human phase 1 study of WEE1 inhibitor APR-1051 in patients with advanced solid tumors harboring cancer-associated gene alterations

Abstract Background: WEE1 tyrosine kinase plays a key role in cell cycle regulation and DNA damage responses, acting as a principal gatekeeper of the G1-S and G2-M cell cycle checkpoints. Thus, inhibition of WEE1 can result in high cyclin-dependent kinase 1 and 2 activities, leading to aberrant cell cycle progression. Increasing premature entry into mitosis and subsequent apoptosis via WEE1 inhibition is one potential approach to killing cancer cells effectively. APR-1051 is an orally bioavailable, highly potent, small molecule inhibitor of WEE1 that has demonstrated in vivo anti-proliferative activity in multiple cancer cell lines and high selectivity for WEE1 versus polo-like kinases 1, 2, and 3. Increased selectivity for WEE1 may reduce the myelosuppressive toxicity (e.g., limiting Grade 3 toxicities) reported with other WEE1 inhibitors. Methods: The primary aim of this multi-center, open-label Phase I study is to characterize the safety, dose-limiting toxicities (DLTs), maximum tolerated dose (MTD)/maximum administered dose (MAD) and recommended Phase 2 dose (RP2D) of APR-1051 in patients with advanced solid tumors harboring cancer-associated gene alterations. Secondary objectives include evaluating the pharmacokinetic (PK) properties of APR-1051, assessing the effect of food on its PK, and its preliminary efficacy per RECIST version 1.1. The exploratory objective is to assess the pharmacodynamic effects of APR-1051. For dose escalation, an accelerated titration followed by a BOIN design will be utilized to determine the MAD/MTD. Upon completion of the dose escalation, two suitable doses and schedules of single-agent APR-1051 will be determined for further investigation in dose selection optimization. Key inclusion criteria are age at least 18 years with advanced solid tumor and cancer-associated gene alterations (e.g., amplification/overexpression of CCNE1 or CCNE2, deleterious mutations in FBXW7 or PPP2R1A), ECOG PS 0 or 1, and adequate organ function. Key exclusion criteria are cancer therapy within 3 weeks or at least 5 half-lives, prior radiation therapy at the target lesion except if evidence of disease progression, unresolved therapy-related AEs, investigational agent within 5 half-lives or 30 days of study drug, prior WEE1 inhibitor, CNS metastases or unstable involvement, secondary malignancies that are active and/or require therapy, and concomitant moderate/strong inhibitors/inducers of CYP3A4/5, MDR1, or BCRP. Up to 79 patients will be enrolled at 3 to 5 sites in the United States. Citation Format: Timothy A. Yap, Crystal Miller, David Stenehjem, Eric J. Brown, Mike Carleton, Nadeem Q. Mirza. First-in-human phase 1 study of WEE1 inhibitor APR-1051 in patients with advanced solid tumors harboring cancer-associated gene alterations [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT195.

457 A Phase I Trial of Tazemetostat and Venetoclax in Relapsed and Refractory non-Hodgkin Lymphoma

OBJECTIVES/GOALS: Primary Objective: To evaluate the safety of venetoclax plus tazemetostat in patients with relapsed and refractory (R/R) Follicular lymphoma (FL) or Diffuse large B-cell lymphoma (DLBCL) Secondary Objectives: 1. To evaluate the tolerability of the combination of T+V using patient reported outcomes (PROs) 2. To evaluate the efficacy of T+V METHODS/STUDY POPULATION: Study design: A phase I trial in two parts: Part 1: a single-arm, open-label sequential dose escalation (3+3) of venetoclax in combination with tazemetostat, given at its recommended phase II dose (RP2D) of 800mg BID, to determine the maximum tolerated dose (MTD) of venetoclax. Part 2: two expansion cohorts (R/R DLBCL and R/R FL) to further characterize the safety and tolerability of the combination, and to estimate the preliminary efficacy. We will perform additional exploratory studies to determine if there are biologic features that correlate with responses. Eligibility: up to 38 patients aged >/=18 years old with histologically confirmed diagnosis of FL or DLBCL who have received at least 2 prior lines of therapy for lymphoma with evidence of disease progression and meet inclusion criteria RESULTS/ANTICIPATED RESULTS: Primary Endpoints: 1. Incidence and severity of adverse events as per CTCAEv5 2. Dose-limiting toxicity (DLT) of T+V, and to establish the maximum tolerated dose (MTD) of V plus fixed dose T Secondary Endpoints: 1. Incidence and Severity of toxicity and quality of life as per PRO-CTCAE and FACT-Lym 2. Overall response rate (ORR), complete response (CR) rate, partial response (PR) rate, as per Lugano criteria 3. Duration of response (DOR), progression-free survival (PFS), overall survival (OS)Exploratory Endpoints: 1. Characterization of tumor cells pre-treatment (including EZH2 mutations and BCL2 translocations) 2. Phenotypic analysis (including BCL2 expression) and quantification of the tumor microenvironment in pre-treatment samples (using image mass cytometry)Explorato DISCUSSION/SIGNIFICANCE: There is a need for novel therapeutic approaches to improve the prognosis for patients with R/R NHL. Preclinical data suggests synergism between the pair.5 Importantly, this represents a chemotherapy-free, oral regimen. If well tolerated, this could present an alternative therapeutic option for patients ineligible for more intensive therapies.

Abstract 937: Prioritizing treatment targets for an adolescent with metastatic processive malignancy using proteomics and personalized xenograft models within an actionable timeframe

Abstract Translation of precision oncology data into feasible precision therapies for hard-to-cure childhood, adolescent and young adult malignancies remains a significant challenge. Identifying therapeutic targets at the protein and pathway level and demonstrating treatment response in personalized models hold great promise, particularly for combination therapies, but may be considered complex and time consuming. Here, we present the case of an adolescent with metastatic, progressive spindle epithelial tumor with thymus-like differentiation (SETTLE) and evaluate how proteomics combined with rapid patient-derived models can identify treatment options not apparent at the genome or transcript level. Mass spectrometric proteome analysis of macro-dissected tumor and adjacent normal from formalin fixed paraffin embedded sections was completed within two weeks of biopsy and identified key proteins involved in one-carbon metabolism, including SHMT2 and DHFR as possible targets for single or combination therapy. Elevated SHMT2 levels were validated by immunohistochemistry and compared to levels across AYA tumors. Based on the suitability for an innovative therapy trial, we prioritized single-agent sertraline, a commercially available anti-depressant medication that inhibits SHMT2, and confirmed a positive drug response in both chicken chorioallantoic membrane (CAM) and larval zebrafish xenografts generated from the patient. Retrospective expansion in a murine xenograft enabled metabolic tracing on isolated SETTLE- patient-derived xenograft cells using 13C6-glucose confirming SHMT2 activity and response to in vitro treatment. Following failure of cytotoxic chemotherapy and second-line sorafenib treatment, a monotherapy trial of sertraline was initiated by the patient but stopped after 8 weeks after evidence of progressive disease. Possible combination therapies were evaluated further in the patient-derived models. Combining sertraline with the common antibiotic trimethoprim, resulted in enhanced growth inhibition of SETTLE cells in the larval zebrafish xenografts. Significance: Overall, we demonstrate that proteomics and personalized xenograft models may provide supportive pre-clinical data in a clinically meaningful timeframe to support medical decision-making and impact clinical practice. Citation Format: Georgina D. Barnabas, Tariq A. Bhat, Verena Goebeler, Pascal Leclair, Nadine Azzam, Nicole Melong, Jason N. Berman, Jennifer A. Chan, Donna L. Senger, Seth Parker, Christopher A. Maxwell, Gregor S. Reid, Jonathan Bush, Caron Strahlendorf, Rebecca Deyell, C James Lim, Philipp F. Lange. Prioritizing treatment targets for an adolescent with metastatic processive malignancy using proteomics and personalized xenograft models within an actionable timeframe [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 937.

Care Pathway at a Cancer Center for the Administration of Radiometabolic Therapy with 177Lu-PSMA in Patients with Metastatic Castration-resistant Prostate Cancer.

To present a clinical care model for the administration of 177Lu-labeled prostate-specific membrane antigen (PSMA) in radiometabolic therapy for metastatic castration-resistant prostate cancer (mCRPC) at the National Cancer Institute (NCI) of Bogotá, Colombia. A care model was designed for patients with mCRPC based on the VISION study, a prospective, phase III, multicenter, open-label, randomized study in patients with positive 68Ga-PSMA positron emission tomography/computed tomography who had progressed to taxane and androgen therapy, to receive 177Lu-PSMA-617 combined with the best standard of care vs. the best standard of care alone. The care pathway provided to patients was developed by the Nuclear Medicine Group of the NCI and is the result of adjustments and improvements in the care process and the updating of the literature. A systematic and efficient care model was formalized and implemented for the administration of 177Lu-PSMA therapy in patients with mCRPC who had previously been treated with at least one androgen receptor pathway inhibitor and one or two taxane regimens, with evidence of disease progression. An optimized process of care based on the determinants of clinical outcomes was developed for patients who received this type of radiometabolic therapy.

Single-institutional analysis of radiotherapy and orthotopic liver transplant for patients with unresectable cholangiocarcinoma.

466 Background: There is increasing interest in effective strategies for locoregional therapy for cholangiocarcinoma, particularly given the evolving role of orthotopic liver transplant (OLT) for select patients. This single-institution retrospective study compares the clinical efficacy and toxicity of stereotactic body radiotherapy (SBRT), conventional fractionation chemoradiation (CRT), or SBRT as a bridge to OLT in patients with unresectable early stage and locally advanced cholangiocarcinoma. Methods: We reviewed a total of 31 patients from 2010 to 2023 with intrahepatic cholangiocarcinoma (ICC), extrahepatic cholangiocarcinoma (ECC), and perihilar cholangiocarcinoma who were treated with SBRT (n=22) or CRT (n=9). SBRT was delivered in 1-5 fractions, median dose of 40 Gy, and dose ranging from 16 Gy to 60 Gy. CRT was delivered in 13-28 fractions, median dose of 50.2 Gy, and dose ranging from 45 Gy to 52.5 Gy. Kaplan-Meier was used to analyze overall survival (OS), progression-free survival (PFS), and local control (LC). Acute and late G3+ toxicity was scored using CTCAE, version 5.0. Results: We identified 13 patients with ICC, 5 with ECC, and 13 with perihilar disease where SBRT or CRT was part of upfront definitive treatment. With a median follow-up time of 11 months, there was no statistical difference between SBRT vs. CRT for OS (median 21 vs. 22 months; p=0.36), PFS (median 14.2 vs. 11 months; p=0.09), and 1-year LC (73.2% vs. 66.7%; p=0.10). However, SBRT appeared to have lower proportions of acute grade 3+ (9.1% vs. 33.3%) and chronic grade 3+ toxicities (22.7% vs. 33.3%). Four patients with early stage perihilar or ICC underwent SBRT as successful bridge to transplant, with no evidence of disease progression at 5.4 months. An additional 2 out of 8 patients were removed from protocol due to disease progression and 2 others remain on protocol, awaiting OLT. Conclusions: In our series of unresectable cholangiocarcinoma, we found no difference in OS, PFS, and LC for patients treated with SBRT vs. CRT, although the former appeared to have lower toxicity and a trend towards improved PFS. Further research is needed to compare SBRT and CRT as definitive treatment or bridge to OLT for patients with unresectable cholangiocarcinoma.

Atezolizumab and Platinum Plus Pemetrexed With or Without Bevacizumab for Metastatic Nonsquamous Non–Small Cell Lung Cancer

The combination of an antibody to programmed cell death-1 (PD-1) or to its ligand (PD-L1) with chemotherapy is the standard first-line treatment for metastatic non-small cell lung cancer (NSCLC). Bevacizumab is expected to enhance the efficacy not only of chemotherapy but also of PD-1/PD-L1 antibodies through blockade of vascular endothelial growth factor-mediated immunosuppression, but further data are needed to support this. To evaluate the efficacy and safety of bevacizumab administered with platinum combination therapy and atezolizumab in patients with advanced nonsquamous NSCLC. An open-label phase 3 randomized clinical trial was conducted at 37 hospitals in Japan. Patients with advanced nonsquamous NSCLC without genetic driver alterations or those with genetic driver alterations who had received treatment with at least 1 approved tyrosine kinase inhibitor were enrolled between January 20, 2019, and August 12, 2020. Patients were randomly assigned to receive either atezolizumab plus carboplatin with pemetrexed (APP) or atezolizumab, carboplatin plus pemetrexed, and bevacizumab (APPB). After 4 cycles of induction therapy, maintenance therapy with atezolizumab plus pemetrexed or with atezolizumab, pemetrexed, and bevacizumab was administered until evidence of disease progression, development of unacceptable toxic effects, or the elapse of 2 years from the initiation of protocol treatment. The primary end point was progression-free survival (PFS) as assessed by blinded independent central review (BICR) in the intention-to-treat (ITT) population. A total of 412 patients were enrolled (273 men [66%]; median age, 67.0 [range, 24-89] years) and randomly assigned, with 205 in the APPB group and 206 in the APP group of the ITT population after exclusion of 1 patient for good clinical practice violation. The median BICR-assessed PFS was 9.6 months with APPB vs 7.7 months with APP (stratified hazard ratio [HR], 0.86; 95% CI, 0.70-1.07; 1-sided stratified log-rank test; P = .92). According to prespecified subgroup analysis of BICR-assessed PFS, an improved PFS with APPB vs APP was apparent specifically in driver oncogene-positive patients (median, 9.7 vs 5.8 months; stratified HR, 0.67; 95% CI, 0.46-0.98). Toxic effects related to bevacizumab were increased in the APPB group. The findings of this trial did not show superiority of APPB over APP for patients with nonsquamous NSCLC; however, this regimen showed a similar tolerability and improved survival relative to APP in patients with driver oncogenes. Japan Registry of Clinical Trials Identifier: jRCT2080224500.

High Rate of Disease Progression in Patients with Low-Risk Myelofibrosis (MF) Enrolled in the Prospective, Real-World MOST Study

Background: Patients (pts) with low-risk MF are typically excluded from interventional clinical trials, thus data regarding the prognosis of this pt population are largely derived from retrospective analyses. The Myelofibrosis and Essential Thrombocythemia Observational Study (MOST; NCT02953704) is a prospective observational study that enrolled pts with low-risk MF defined by Dynamic International Prognostic Scoring System (DIPSS) criteria. In this analysis, we report disease progression, defined by worsening of clinical or laboratory parameters, in MF pts during the MOST study. Methods: Criteria for enrollment in MOST were confirmed locally and centrally, and included a physician-reported diagnosis of MF (PMF, post-PV, or post-ET) and lack of any DIPSS risk factors except for age >65 y. Of the 232 MF pts enrolled, 205 met this criteria upon central review and were included in this analysis as Cohort A; the remaining 27 pts were enrolled despite having ≥1 DIPSS risk factor (other than age >65 y) and were analyzed separately as Cohort B. Data were collected as previously described (Gerds A. CLML. 2022;22:e532). Disease progression on study was defined as the acquisition of 1 of the following criteria: hemoglobin (Hb) <10 g/dL, platelets <100×10 9/L, presence of constitutional symptoms (weight loss, fever, or sweats), new or worsening splenomegaly, blasts >1%, WBC count >25×10 9/L, death due to disease progression, leukemic transformation (LT), or >1 RBC transfusion. Median (range) follow-up was 52.9 months (42-68). Results: In Cohort A, 120/205 pts (58.5%) had evidence of disease progression during the study. Baseline characteristics comparing pts with vs without disease progression were similar; although compared with pts without progression, those who progressed were older at diagnosis (median [range], 65.9 [21-88] vs 62.9 [35-86] y), older at enrollment (median [range], 70.5 [35-88] vs 66.0 [35-88] y), and had longer median (range) time from diagnosis to enrollment (1.9 [0-38] vs 1.4 [0-24] y). Similar percentages of pts with vs without progression were receiving MF-directed therapy at enrollment (59.2% vs 61.2%); most common treatments were ruxolitinib (33.3% vs 14.1%) and hydroxyurea (22.5% vs 36.5%). Of pts in Cohort A tested for JAK2 mutations, 66/93 (71.0%) with disease progression and 42/65 (64.6%) without were positive. Of pts tested for CALR mutations, 16/21 (76.2%) with disease progression and 17/23 (73.9%) without were positive. Among the 120 pts with progression, 64 (53.3%) met 1 criteria, 27 (22.5%) met 2 criteria, and 29 (24.2%) met ≥3 criteria during the study. The most common progression criteria met were Hb <10 g/dL (47.5%), platelets <100×10 9/L (31.7%), constitutional symptoms (30.8%), and new/worsening splenomegaly (28.3%) (Table 1). Median (95% CI) durations to 1st, 2nd, and 3rd progression criteria were 24.9 (19.2-34.7), 28.2 (14.3-NE), and 11.6 (8.9-26.5) months, respectively (Figure 1). Of pts who progressed, 6 (5.0%) developed LT and 12 (10.0%) died due to disease progression. In Cohort B at time of enrollment, 25/27 pts (92.6%) met 1 progression criteria. The most frequent was Hb <10 g/dL (13/27 [48.1%]), followed by WBC count >25×10 9/L (7/27 [25.9%]); constitutional symptoms (4/27 [14.8%]), and blasts >1% (1/27 [3.7%]); 1 pt (3.7%) met 2 progression criteria (Hb <10 g/dL and constitutional symptoms), and 1 pt (3.7%) met 3 progression criteria (blasts >1%, constitutional symptoms, and WBC count >25×10 9/L). Eight of 27 pts (29.6%) had evidence of further disease progression while on study (Table 1). The most common new progression criteria met were Hb <10 g/dL and platelets <100×10 9/L (each 5/8 [62.5%]) and constitutional symptoms and new/worsening splenomegaly (each 3/8 [37.5%]). Conclusions: This real-world observational analysis from MOST is the first prospective analysis of disease progression in low-risk myelofibrosis. The results show that with over 4 y of follow-up, nearly 60% of pts with low-risk MF had evidence of disease progression; 17/205 pts (8.3%) developed LT or died (both occurred in 1 pt). Median time to acquisition of 1st and 2nd disease progression criteria was approximately 2 y, respectively, decreasing to approximately 1 y for the 3rd criteria; this indicates a slow but increasing rate of progression over the course of the study. These data provide real-world insight into disease progression rate in pts with low-risk myelofibrosis.

Clinical Outcomes in Patients with Waldenström Macroglobulinemia (WM) Receiving Ibrutinib on the Phase 3 ASPEN Study ≥1 Year After Transitioning to Zanubrutinib

Introduction: Bruton tyrosine kinase inhibitors (BTKi) have become a standard of care in treating patients with WM. Zanubrutinib, a next-generation BTKi, was developed to ensure greater BTK specificity and potency than ibrutinib to avoid toxicities associated with off-target binding and improve efficacy. The ASPEN study (BGB-3111-302; NCT03053440) directly compared outcomes of zanubrutinib and ibrutinib treatment in patients with MYD88-mutated WM. The BGB-3111-LTE1 study (LTE1, NCT04170283) is a long-term extension study to which eligible patients can enroll following participation in parent studies of zanubrutinib for treatment of B-cell malignancies, including patients from comparator treatment arms. Here, we report safety and efficacy outcomes in ibrutinib-tolerant patients from ASPEN at ≥1 yr from initiation of zanubrutinib in the LTE1 study. Methods: All patients (N=47) who enrolled in LTE1 from the ibrutinib arm of ASPEN (Arm B) were included in this ad hoc analysis. Patients began treatment with zanubrutinib at 320 mg total daily dose upon enrollment. Safety and efficacy outcomes were evaluated, including the recurrence of ibrutinib treatment-emergent AEs (TEAEs). Investigators assessed disease response every 6 months, or more frequently as indicated, based on the modified Owen criteria and using parameters at ASPEN study entry (BTKi pretreatment); alternatively, investigators could assess “no evidence of progressive disease” using their clinical judgment. Results: Between June 26, 2020, and June 23, 2022, 47 patients treated with ibrutinib in ASPEN enrolled in LTE1. At ASPEN enrollment, 37 patients (79%) had R/R WM, with a median of 1 prior therapy (range: 1-6). At enrollment to LTE1, the median age was 73 yr (range: 44-89); the median time since ibrutinib treatment initiation was 50.4 months (range: 26-59.3). As of June 23, 2023, 40 patients (85%) remained on study treatment; the median zanubrutinib treatment duration was 15.3 months (range: 5.1-22.1) and the overall median treatment duration with BTKi was 65.5 months (range: 48.1-76.7). The median time from ASPEN study discontinuation to zanubrutinib initiation in LTE1 was 0.07 months (range: 0-4). During LTE1, grade ≥3 and serious TEAEs occurred in 23% and 13% of patients, respectively; infections (6.4%, all COVID-19) were the only grade ≥3 TEAEs occurring in more than 2 patients and no serious TEAEs occurred in more than 2 patients. Worsening of ibrutinib TEAEs of interest for BTKi treatment following the transition to zanubrutinib included infections (n=3), all of which were due to COVID-19 ( Fig 1), anemia (n=1), and neutropenia (n=1). Of the 7 patients who experienced cardiovascular AEs (8 events) in LTE1, all but 1 with grade 2 tachycardia had experienced at least 1 cardiovascular AE during ibrutinib treatment on ASPEN. No new or recurrent episodes of hypertension occurred after patients switched from ibrutinib to zanubrutinib, and no ongoing hypertension worsen. No resolved ibrutinib treatment-emergent atrial fibrillation/flutter recurred; no ongoing atrial fibrillation/flutter worsened following the transition to zanubrutinib. One new case of atrial fibrillation occurred on LTE1 Day 12 in a pt with an extensive cardiovascular history who also experienced grade 2 pericarditis 2 days prior (LTE1 Day 10). No cardiovascular TEAE led to death in LTE1; two deaths occurred both due to COVID-19. Categorical best overall response (BOR) in LTE1 was unchanged from the last response in ASPEN in 34 patients (72%) but improved in 10 patients (21%), including 1 pt in PR and 1 pt in VGPR at the end of ASPEN who had a deepening response to CR. Response worsened from PR to MR in 1 pt, 1 pt had “no evidence of progressive disease,” and 1 pt discontinued before response assessment. Median change in [IgM] from the last response in ASPEN to BOR in LTE1 was -36 mg/dL (-3490, +730); [IgM] was stable or decreased in 29 (73%) of the 40 evaluable patients ( Fig 2). Conclusions: With a median treatment duration of 15 months, worsening of ibrutinib TEAEs of interest for BTKi treatment following transition to zanubrutinib was rare, as was the emergence of new events. Response was maintained or improved in 96% (n=44/46) of efficacy-evaluable patients. While limited by sample size and nonrandomized/ ad hoc analysis, data suggest that patients may transition from ibrutinib to zanubrutinib without compromising safety or efficacy; long-term follow-up is ongoing.

Decreased Survival Among Patients with Indolent Systemic Mastocytosis: A Population-Level Retrospective Cohort Analysis Using Healthcare Claims Dataset

Background Systemic mastocytosis (SM) is a rare, clonal mast cell disease driven by the KIT D816Vmutation in ~95% of cases and can be subdivided into two predominant subtypes - advanced SM (AdvSM) and indolent SM (ISM). AdvSM comprises ~15% of all patients and is characterized by mast cell proliferation and infiltration causing subsequent dysfunction of various organ systems, leading to reduced overall survival. Indolent systemic mastocytosis (ISM) comprises the bulk of the remaining ~85% of patients and is characterized by a less severe clinical course that is nevertheless associated with a significant symptom burden that may worsen over time, poor quality of life, and the potential for life-threatening anaphylaxis. Recent epidemiologic data indicate ISM is a heterogenous disease. A meaningful subset of patients with disease risk factors demonstrates high symptom burden, which may be associated with higher rates of disease progression and increased risk of death (Sperr, et al. Lancet Hematol. 2019). Building upon this work, we conducted an analysis to evaluate overall survival (OS) in ISM patients. Methods Using a nationally representative health claims dataset provided by Komodo Health covering 230 million US patients (2015 to 2022), we identified 8,332 patients with ISM using a claims-based algorithm. This algorithm leverages combinations of ICD-10 dx codes for SM and organ dysfunction, procedure codes (bone marrow biopsy), and use of SM-directed therapies (Mukherjee et al ASH 2022). Patients were included if full medical and pharmacy claim information was available for >12 consecutive months post-diagnosis, and median follow-up was 4.0 years. ISM was inferred as a dx if only the broad systemic mastocytosis ICD-10 code was used (D47.02) and there was no preceding evidence of AdvSM or an associated hematologic neoplasm. Disease progression to AdvSM was inferred if there was subsequent evidence of mast cell leukemia, aggressive SM, or an associated hematologic neoplasm OS was then calculated, anchored to the first observed ICD-10 dx code for SM. Mortality information was available within the claims dataset and was additionally inferred if a patient did not generate any medical or pharmacy claims for 12 or more consecutive months. Three, independent non-SM control cohorts (N=2000 each) were established for comparison, based on a stratified sampling strategy matched by gender, age, Charlson Comorbidity Index, payer status, and race/ethnicity of the ISM population. Multiple cohorts were plotted to illustrate consistency in survival across independently-sampled control cohorts. As positive control, we compared OS with a cohort of patients with ASM, a disease cohort with known increased mortality. Results We observed a statistically significant difference in OS among patients with ISM versus the matched non-SM control cohorts ( p<0.0001, with a log-rank hazard ratio of 1.64; Figure 1A). Excess mortality was noted among ISM patients with or without evidence of disease progression ( p<0.0001, with a hazard ratio of 1.44) compared to matched non-SM cohorts ( Figure 1B). As expected, OS was worst in patients with AdvSM ( p<0.0001, with a hazard ratio of 6.64). The ISM cohort presented to the emergency room (ER) 0.70 times per year, compared to 0.31 times per year for the combined non-ISM control cohorts, based on the sum of ER visits observed across the cumulative cohort observation period. Patients with ISM who died during the study interval had the highest frequency of ER visits, at a rate of 1.09 visits per year. Conclusions This is the first and the largest population-level analysis of OS in the ISM population in the US. Results demonstrate a modest but statistically significant decrease in survival among these patients even early in their disease course (first 4 years). This increase in mortality was observed even among patients with no evidence of progression to advanced SM and was additionally associated with >2x higher rates of ER visits over the observation period. These results suggest that acute, severe symptoms of SM may contribute to the excess mortality seen among patients with ISM and warrant focused research to identify specific patient characteristics or disease features in ISM that confer higher risk of mortality.

A Phase II Study of Isatuximab in Combination with Pomalidomide and Dexamethasone in Patients with Multiple Myeloma Progressing on or after One Line of Lenalidomide-Containing Therapy

Introduction Relapse in patients (pts) with multiple myeloma (MM) is a common occurrence, resulting in a continued need for novel treatment approaches. Isatuximab (Isa), a monoclonal antibody (mAb), combined with pomalidomide (Pom) and dexamethasone (Dex), is indicated for the treatment of pts with relapsed/refractory multiple myeloma who have received ≥2 prior therapies including lenalidomide and a proteasome inhibitor and have demonstrated disease progression on the last therapy. The current study aims to evaluate the efficacy and safety of IsaPomDex in pts with MM relapsing for the first time after one line of treatment containing lenalidomide (Len). Methods EAE115 (NCT05298683) is an ongoing, investigator-initiated, phase II, prospective, open-label, multicenter study aiming to enroll 108 pts. Eligible pts are adults with documented MM who have evidence of progressive disease, by the International Myeloma Working Group criteria, on or after treatment with only one prior line of anti-myeloma therapy with lenalidomide (≥2 cycles, alone or in combination) and a proteasome inhibitor. Pts must also have adequate bone marrow and hepatic function and an Eastern Cooperative Oncology Group performance status (ECOG PS) ≤2. Excluded are pts with previous anti-myeloma therapy with any anti-CD38 mAb, pomalidomide, or stem cell transplant within 12 weeks before treatment initiation. Pts receive six 28-day cycles of Isa 10 mg/kg (once weekly [QW] by intravenous [IV] infusion on days 1, 8, 15, and 22 in cycle 1 and days 1 and 15 in subsequent cycles), Pom 4 mg (per Os on days 1-21, each cycle), and Dex 40 mg or 20 mg for pts ≥75 years old (per Os or IV on days 1, 8, 15 and 22, each cycle). Fifteen to 60 minutes before Isa infusions, patients receive pre-medications to mitigate potential infusion-related adverse reactions. Following initial 6 cycles, pts achieving at least very good partial response (VGPR) are randomized 1:1 to receive Isa (Q2W or Q4W) plus PomDex, and pts achieving <VGPR continue treatment with Isa (Q2W) plus PomDex. Treatment is given until progressive disease, death, unacceptable adverse events (AEs), lost to follow-up, or consent withdrawal. The study primarily evaluates the overall response rate (ORR; defined as partial response [PR] or better) to IsaPomDex therapy at six months. Adverse events are classified using the Medical Dictionary for Regulatory Activities. Herein, we present safety and efficacy data for all treated patients (cut-off date 15/05/23. Results Twenty pts had received at least one dose by the cut-off date, of whom 16 (80.0%) were continuing with IsaPomDex treatment; four (20.0%) pts had discontinued due to physician or pt decision or progressive disease or death. At baseline (cycle 1, day 1), pts had a median age of 72.0 years (range: 60.0-85.0), 10 (50.0%) were male, and 13 (65.0%) had ECOG PS 0. Eleven (55.0%) pts were at stage II by the revised International Staging System, 9 (45.0%) pts had lytic bone lesions, 5 (25.0%) pts had high-risk cytogenetics, and 1 (5.0%) pt had soft-tissue plasmacytomas (Table 1). Regarding previous treatment outcomes, 14 (70.0%) pts had achieved ≥VGPR (stringent complete response, 2 [10.0%] pts; complete response, 2 [10.0%] pts; VGPR, 10 [50%] pts). Five (25%) and 1 (5.0%) pts achieved partial and minimal response, respectively. Six (30.0%) pts had received ASCT in the prior line. At a median follow-up of 3.4 (range: 0.6-6.1) months, the median number of IsaPomDex cycles received was 3.0 (range: 1.0-7.0); one (5.0%) pt received six treatment cycles. Of the 18 (90.0%) response evaluable pts (2 pts were ongoing without 2 efficacy assessments) VGPR and PR were achieved by 4/18 (22.2%) and 9/18 (50.0%) pts, respectively. ORR was achieved by 13/18 (72.2%) pts, and the median (range) time from IsaPomDex study dose to first response (≥PR) was 1.0 (range: 0.9-1.3) months. Thirteen (65.0%) pts had ≥1 treatment-emergent adverse events (TEAE). Of these pts, 10 (50.0%) had a ≥1 grade (gr)≥3 TEAE and 4 (15.0%) had ≥1 gr ≥3 serious TEAE. The most common TEAEs were neutropenia in 9 pts (45.0%), anaemia in 3 pts (15.0%) and fatigue in 3 pts (15.0%). The most common gr ≥3 TEAE was neutropenia in 7 pts (35.0%) (Table 2). Conclusions Second-line treatment with IsaPomDex in pts with MM who have progressed on or after one Len-containing line of treatment appears to be effective, although longer follow-up is needed to assess its efficacy. No new safety signals were observed with the combination.

Identifying Causes of Unscheduled Healthcare Interactions and Changes to Patient Disposition in Individuals Receiving Outpatient Commercial Bispecific Antibody Therapy in Relapsed/Refractory Multiple Myeloma (RRMM)

Introduction: Teclistamab is a BCMA targeting bispecific antibody that was FDA approved for treating relapsed/refractory multiple myeloma (RRMM) based off the results of the MajesTEC-1 trial (Usmani S, et al. Lancet 2021, Moreau P, et al. N Engl J Med 2022), and is the first bispecific antibody approved for myeloma treatment. While patients included in the MajesTEC-1 study were monitored closely per trial protocols, little is known about what patient-reported care concerns and education gaps may exist outside of a trial setting with standard of care teclistamab and whether these gaps lead to a high number of unscheduled healthcare interactions. Methods: We retrospectively analyzed patient reported symptom concerns for commercial teclistamab patients at Memorial Sloan Kettering Cancer Center (MSKCC) via review of the electronic health record for a 4-month observation period following treatment initiation. Patients were included in the study if they had a response to teclistamab (per IMWG criteria), remained on treatment for at least 4 months as of our data cut-off (07/20/2023), and did not have evidence of disease progression during the observation period. Collected data included all unscheduled healthcare visits, including urgent care visits, emergency room visits, and hospital admissions. We also evaluated all outpatient communications, including telephone calls to physicians' offices and messages sent to physicians' offices through MSKCC's online patient portal. The total observation period included the first 4 months of therapy, during which patients were scheduled to receive treatment weekly and be seen by their physicians at regular 4-week intervals. Results: We identified 52 patients treated with teclistamab at our center as of the data cut-off, 19 of which met our inclusion criteria. Of note, this population had poorer performance status (89% vs 67% ECOG ≥1) and had more heavily pretreated disease (6 vs 5 median prior lines of therapy) when compared to the MajesTEC-1 population, with the majority not being eligible for MajesTEC-1 per its criteria. Within this population, 79% of patients communicated with their physicians' offices outside of their scheduled monthly appointments, with an average of 2.3 (0-8) communications sent per patient during the 4-month observation period. The most common reason for communication was upper respiratory tract infection (URI) symptoms, accounting for 24% of all communications. Other notable reasons included gastrointestinal (GI) symptoms (20%), disease related pain (13%), injection site reactions (9%) and symptoms of volume overload (9%). Unscheduled visits included 8 urgent care (UC) visits, and 20 emergency department (ED) visits involving 11/19 patients. The 20 ED visits led to 16 inpatient admissions, not including planned admissions for step-up dosing (data summarized in Figure 1), with a median length of stay of 4 days (2-24 days). URI symptoms triggered 50% of UC visits and 40% of the ED visits not leading to inpatient admission, but only accounted for 6% of hospital admissions. The most common cause of hospital admission was a non-URI acute infection (29%). Conclusions: Our data suggest that RRMM patients being treated with outpatient teclistamab have frequent unscheduled healthcare interactions. The high prevalence of URIs in our population indicates that infection rates in this frequently hypogammaglobulinemic patient population may be underreported. However, these do not frequently lead to inpatient admissions or to significant morbidity/mortality. Overall, teclistamab patients would likely benefit from improved patient education with regards to expected side effects of therapy, with pre-existing management plans in place for URIs, GI symptoms, and injection site reactions. Applying these principles may limit excessive healthcare visits for patients, particularly in those with heavily relapsed/refractory myeloma with poor disease prognosis. Data from additional patients, including patients receiving step-up dosing as outpatients as part of a pilot study, will be presented at the meeting.

Suppression of KRAS and CBL Mutations and Hematological Improvement By Lenzilumab and Azacitidine Treatment in Proliferative Chronic Myelomonocytic Leukemia

Introduction: Mutations in RAS-pathway genes ( NRAS, KRAS, CBL) are amongst the most common somatic mutations in cancer and historically resistant to most therapies. Targeted therapies that impact the RAS-pathway constitute a major unmet need in oncology. The proliferative form of chronic myelomonocytic leukemia (CMML) is commonly associated with RAS-pathway mutations and has a high propensity to develop into acute myeloid leukemia. In pre-clinical models, Lenzilumab (LENZ; Humanigen, Inc., Short Hills, NJ), a proprietary Humaneered ® first-in-class monoclonal antibody with best-in-class off-rate and affinity that neutralizes GM-CSF, resulted in a reduction of colony numbers and viability of CMML cells, with the greatest sensitivity in cells possessing RAS-pathway ( NRAS/ KRAS/ CBL) mutations, suggesting benefit in the targeted treatment of CMML. The PREcision Approach to CHronic Myelomonocytic Leukemia (PREACH-M) trial assesses the efficacy of LENZ, in addition to azacytidine (AZA), in CMML subjects with RAS-pathway mutations and high dose sodium ascorbate (ASC) and AZA in CMML subjects without RAS-pathway mutations. Interim data from 11 subjects with RAS-pathway ( NRAS/ KRAS/ CBL) mutations in PREACH-M receiving LENZ/AZA demonstrate reductions in circulating GM-CSF and CRP with 8 subjects achieving complete response or optimal marrow response. This report describes improvements in variant allele frequencies (VAF) for RAS-pathway mutations and hematologic improvements associated with LENZ/AZA treatment in CMML. Methods: PREACH-M is a Phase 2/3 non-randomized, open-label trial in 72 subjects, aged at least 18 years, with newly diagnosed CMML based on the WHO 2016 criteria; and RAS-pathway mutations at a variant allele frequency ≥3%. Subjects received 24 cycles (every 28 days) of AZA (SC; 75 mg/m 2 for 7 days) and LENZ (IV; 552 mg; d1 & d15 of cycle 1 and d1 only for all subsequent cycles). Subjects without RAS-pathway mutations received the same AZA regimen and sodium ascorbate (IV; 30g for 7 days (15g for 1st dose only; 30g thereafter if no evidence of tumor lysis syndrome); PO; 1.1g on all other days). VAF was determined from bone marrow mononuclear cells using a 41-myeloid panel using Illumina Hi-Seq with a depth of 1000x performed on bone marrow aspirates obtained at baseline and Day 1 of treatment cycles 4, 7, and 12. Results: As of July 2023, 11 subjects completed at least 3 months of LENZ/AZA treatments and follow-up sequencing data were available for 10 subjects. Five of 10 subjects showed >10% decrease in VAF for at least one mutation detected at baseline, including 5 decreased alleles in the RAS-pathway ( KRAS, CBL) out of 22 total VAF mutation responses. CBL mutations showed the largest change with a decrease in >50% VAF in three subjects. Decreases in RAS-pathway clones by LENZ/AZA were durable at 6 months. No decreases in VAF for any mutations were observed in 2 evaluable subjects following ASC/AZA treatment. Following 3 months LENZ/AZA treatment, blood monocyte count improved from a baseline of 11.0 ± 6.0 x 10 9/L to 2.0 ± 1.0 x 10 9/L (p=0.030). Blast differential improved from 10.5 ± 5.0% to 4.0 ± 3.5% (p=0.038). Platelet count increased from 90.0 ± 50.0 x 10 9/L to 150.0 ± 60.0 x 10 9/L (p=0.010). Statistical improvements remained durable for at least 6 (n=6) and 12 (n=3) months. Hemoglobin concentration increased 100.0 ± 22.0 g/L to 115.0 ± 10.0 g/L at 3 months (p=NS, n=11) and progressively increased to 122.0 ± 10.0 g/L at 12 months (p=0.024, n=3). Spleen length decreased from 15.0 ± 4.0 cm to 13.0 ± 4.0 cm (p=0.03) and decreased further to 11.0 ± 2.0 cm in subjects who received 12 months of treatment (n=3). No evidence of disease progression or relapse was observed in any subject. Conclusion: In 11 evaluable subjects with proliferative CMML and RAS-pathway mutations, GM-CSF neutralization with LENZ in addition to AZA standard of care, resulted in significant decreases in the proportion of KRAS and CBL mutant leukemic cells, accompanied by clinically significant hematologic improvements and a reduction in splenomegaly. Lenzilumab may have efficacy in preventing outgrowth of RAS-pathway mutations, specifically KRAS and CBL, in the context of CMML and other myeloid malignancies.

Trial in Progress: An Open-Label Expansion Trial Evaluating the Safety, PK/PD, and Clinical Activity of Emavusertib (CA-4948) + Ibrutinib in R/R Primary CNS Lymphoma

Background: Primary central nervous system lymphoma (PCNSL) is a rare and aggressive form of NHL isolated to the central nervous system or vitreoretinal space. Despite high initial rates of responses to available therapies, most PCNLS relapse in two years, presenting a very poor prognosis. Combination with novel therapies may overcome resistance (Guidetti 2023a). Upregulation of the B-cell receptor (BCR/NF-κB) and toll-like receptor (TLR)/NF-κB) signaling axis have been identified as key pathways in the pathogenesis of PCNSL. MYD88 L265P, a widely expressed somatic mutation in more than 70% of PCNSL patients, activates NF-κB signaling through stimulation of BTK and IRAK4. Emavusertib (CA-4948) is a novel, potent oral inhibitor of interleukin 1 receptor-associated kinase 4 (IRAK4), with additional inhibitory activity against FMS-like tyrosine kinase 3 (FLT3) and CDC-like kinases (CLK1/2/4). Targeted inhibition of IRAK4 with emavusertib in PCNSL xenografts indicated sufficient blood brain barrier penetration of emavusertib, target inhibition, and antitumor activity (von Roemeling 2022). Further preclinical studies have demonstrated that emavusertib synergizes with ibrutinib and can re-sensitize and overcome resistance to BTK inhibitors (Guidetti 2023a and 2023b). Initial clinical data have reported responses in BTK-resistant PCNSL and good tolerance of the combination (Iqbal 2022; Grommes 2023). Study Design: This is an ongoing multi-center, open-label trial (NCT03328078) in adult patients with hematologic malignancies to evaluate the safety, PK, and anti-cancer activity of oral administration of emavusertib alone or in combination with ibrutinib. Part Bis an open trial expansion cohort with BTKi relapsed or refractory PCNSL. About 20 evaluable PCNSL patients will be enrolled globally. Patients will receive oral CA-4948 at 100 or 200 mg BID in combination with ibrutinib at 560 mg QD in 28-day cycles until disease progression or intolerable toxicity. The primary endpoint is expanded safety/tolerability; secondary endpoints include ORR, DOR, PFS, OS, and pharmacokinetics. Key inclusion criteria for this expansion cohort: pathologically confirmed diagnosis of PCNSL with evidence of disease progression, measurable disease, relapsed or refractory with no more than 3 lines of prior anti-PCNSL therapy (including BTKi), and absence of residual Grade ≥2 toxicity from prior therapy. Key exclusion criteria: intraocular PCNSL without brain lesion or CSF involvement or significant co-morbidity. Key clinical assessments include brain imaging, CSF- and ocular examinations.

A Single Center Real-World Data Comparing Salvage Autologous Hematopoietic Stem-Cell Transplantation, Selinexor Combo and Elranatamab Alone Among Triple Class Refractory Myeloma Patients: Better Efficacy with Elranatamab

Introduction: A vast majority of multiple myeloma (MM) patients may experience relapse and require multiple lines of therapy. The choice of the next treatment depends on multiple factors including the response, tolerance to prior therapies, as well as access to novel treatments. Among triple-class refractory patients, in real-world settings where CAR-T therapies are not available, options are limited. Here we report a single-center experience comparing salvage autologous hematopoietic stem-cell transplantation (sAHCT), selinexor combinations, and elranatamab in this highly unmet needed group. Patients & Methods: Between January 2015 and June 2023, 50 patients at our center underwent sAHCT for treatment of refractoriness to all available drugs. Salvage AHCT is defined as being transplanted for treatment of MM after evidence of disease progression not responding to second-generation proteasome inhibitors (PI), immunomodulating agents (IMID), or antiCD38 monoclonal antibody. We compared the outcomes of these patients with RRMM patients who had exhausted their treatment options and were progressing on their last line of therapy to receive single agent Elranatamab at a step-up dosing starting with escalating to 72 mg once a week for six months and on alternate weeks thereafter. Selinexor was administered with either Bortezomib(n:8) or Pomalidomide(n:9) at a dose of 60-100 mg/week every 5-6 weeks. Response and disease progression were assessed according to the IMWG criteria. Results: Patients' characteristics and the outcomes are shown in Table. The median age of patients was similar in both groups. Patients were heavily treated with a median of 4 prior lines of therapy (1-17) and 7 out of 13 carried high-risk cytogenetics in elranatamab group. All patients were triple-class refractory. Five patients responded to DCEP bridging therapy prior to sAHCT. Selinexor (n: 11, 64.7%) and elranatamab (n:5 patients,38.5%) were administered after sAHCT. One patient underwent sAHCT due to progression under Selinexor treatment. In the sAHCT group, 68% of patients relapsed within a median of 7.4 months. Median DFS was significantly prolonged with single agent elranatamab (NR) compared to sAHCT (7.3 mos) and Selinexor-combos (7.3 mos) (p=0.4) (Figure). Adverse events on selinexor regimens included fatigue, nausea, and thrombocytopenia which were managed with Selinexor dose adjustment and supportive care. All patients received the recommended step-up priming dose elranatamab regimen, 69.2% of our patients experienced a Grade 1 cytokine release syndrome (CRS) during the first cycle. None of these patients had to stop treatment due to toxicity. Early sAHSCT mortality was not observed either. At the time of the analysis, all patients on Selinexor have progressed after a median follow-up of 14.7 months. Elranatamab patients are currently at 5 months follow-up and 7/ 13 are still on treatment. Conclusion: Upfront AHCT is a cost-effective treatment option with a decreasing efficacy in late relapses. In this RWE study, we have been able to confirm the inferiority of AHCT at late stages. As seen in our series cytogenetic profile worsens with an increase in the prior number of lines of treatment which are both highest among patients who have received elranatamab. Despite these unfavorable features, single-agent elranatamab has been able to attain the highest overall response rates, unfortunately not reflecting on PFS yet, due to short follow-up. Furthermore, two of these had progressed while on a BCMA immunotoxin Rx and have responded to elranatamab. In conclusion, even with short follow-up single-agent elranatamab is a tolerable and highly effective regimen