New Line Of Therapy Research Articles

Real-World Treatment Patterns and Clinical Outcomes Among Patients with Metastatic or Unresectable EGFR-Mutated Non-Small Cell Lung Cancer Previously Treated with Osimertinib and Platinum-Based Chemotherapy.

For patients with epidermal growth factor receptor-mutated (EGFRm) locally advanced/metastatic non-small cell lung cancer (mNSCLC) whose disease has progressed on or after osimertinib and platinum-based chemotherapy (PBC), no uniformly accepted standard of care exists. Moreover, limited efficacy of standard treatments indicates an unmet medical need, which is being addressed by ongoing clinical investigations, including the HERTHENA-Lung01 (NCT04619004) study of patritumab deruxtecan (HER3‑DXd). However, because limited information is available on real-world clinical outcomes in such patients, early-phase trials of investigational therapies lack sufficient context for comparison. This study describes the real-world clinical characteristics, treatments, and outcomes for patients with EGFRm mNSCLC who initiated a new line of therapy following previous osimertinib and PBC, including a subset matched to the HERTHENA-Lung01 population. This retrospective analysis used a US database derived from deidentified electronic health records. The reference cohort included patients with EGFRm mNSCLC who had initiated a new line of therapy between November 13, 2015 and June 30, 2021, following prior osimertinib and PBC. A subset of patients resembling the HERTHENA-Lung01 population was then extracted from the reference cohort; this matched subset was optimized using propensity score (PS) weighting. Endpoints were real-world overall survival (rwOS) and real-world progression-free survival (rwPFS). Confirmed real-world objective response rate (rwORR; partial/complete response confirmed ≥ 28days later) was calculated for the response-evaluable subgroups of patients (with ≥ 2 response assessments spaced ≥ 28days apart). In the reference cohort (N = 273), multiple treatment regimens were used, and none was predominant. Median rwPFS and rwOS were 3.3 and 8.6months, respectively; confirmed rwORR (response evaluable, n = 123) was 13.0%. In the matched subset (n = 126), after PS weighting, median rwPFS and rwOS were 4.2 and 9.1months, respectively; confirmed rwORR (response evaluable, n = 57) was 14.1%. The treatment landscape for this heavily pretreated population of patients with EGFRm mNSCLC is fragmented, with no uniformly accepted standard of care. A high unmet need exists for therapeutic options that provide meaningful improvements in clinical benefit.

Comparative effectiveness of linvoseltamab versus standard-of-care (SOC) treatment (tx) in real-world patients (pts) in the United States (US) with triple-class exposed (TCE) relapsed/refractory multiple myeloma (RRMM).

7561 Background: Pts with TCE RRMM have poor outcomes and a high unmet need, with no established SOC tx. LINKER-MM1 (NCT03761108) is a single-arm, Phase 1/2 study investigating linvoseltamab, a B-cell maturation antigen × CD3 bispecific antibody, in pts with RRMM who were previously treated with a proteasome inhibitor, immunomodulatory drug, and anti-CD38 antibody, or were triple-class refractory (TCR) to these tx. The aim of this study was to contextualize LINKER-MM1 by comparing outcomes with linvoseltamab vs a real-world (RW) external control arm (ECA). Methods: A RW ECA was derived from 2 US electronic health record databases (COTA, Guardian Research Network) of pts who started a new line of therapy (LOT) after classification as TCE or TCR and met key eligibility criteria for LINKER-MM1. Eligibility was assessed at the initiation of each new LOT, and all eligible LOTs were included in the ECA. Data in Phase 2 pts who received linvoseltamab 200 mg in LINKER-MM1 were included (data cutoff: Sep 8, 2023). Inverse probability of tx weighting (IPTW) was used to reduce imbalances between the RW and LINKER-MM1 cohorts. Key prognostic factors were identified using a systematic review and rank ordered by an international committee of MM experts (Kumar et al., 2023). Outcomes included overall response rate (ORR), progression-free survival (PFS), time to next treatment (TTNT), and overall survival (OS). An independent committee of epidemiology and oncology experts reviewed the comparability of the cohorts and endpoint assessments prior to conducting comparative analyses. Results: Comparative analyses were performed in 105 pts in the linvoseltamab cohort and 101 RW pts (137 LOTs). Following IPTW, the distribution of cytogenetic risk, age, TCR status, Eastern Cooperative Oncology Group Performance Status, and platelet count were balanced between the 2 cohorts (absolute standardized mean difference <0.10). After adjustment, pts receiving linvoseltamab had significantly improved ORR, PFS, TTNT, and OS vs the RW ECA (see table). Conclusions: Linvoseltamab significantly improved outcomes vs RW SOC in the US, highlighting its potential as a highly effective tx in pts with TCE RRMM. [Table: see text]

Abstract PO3-06-05: Association of tumor-derived extracellular vesicles with circulating tumor DNA alterations in metastatic breast cancer patients: exploring differences in inflammatory breast cancer

Abstract Background: Liquid biopsy provides a real-time assessment of metastatic breast cancer (MBC). Recently, the complementary prognostic value of tumor-derived extracellular vesicles (tdEVs) and circulating tumor cells (CTCs) has been reported. We have previously confirmed the strong prognostic significance of CTCs and tdEVs in inflammatory breast cancer (IBC). While previous studies have reported the association of CTCs with circulating tumor DNA (ctDNA) alterations in MBC, no evidence is available for tdEVs. This study aimed to analyze the association of tdEVs with ctDNA alterations, to investigate the molecular pathways underlying their presence. Moreover, we explored potential differences of this association in patients (pts) with IBC to provide a comprehensive liquid biopsy-based portrait of this aggressive subtype of BC. Methods: Blood samples were collected from 355 pts with MBC before starting a new line of therapy at Northwestern University (Chicago, IL) between 2016 and 2021 (NU16B06 trial). For CTCs and tdEVs analysis, 7.5 mL of blood was processed with the CellSearch® system. The ACCEPT software was applied to CellSearch® images to automatically enumerate CTCs and tdEVs. Positivity cutoff was ≥5 for CTCs, while tdEV cutoff points were < 20 (low), 20-79 (intermediate), and ≥80 (high). For ctDNA analysis, matched plasma samples (± 1 month) were analyzed with the Guardant360™ NGS platform for the detection of somatic single nucleotide variants (SNVs) and copy number variations (CNVs), which were classified into oncogenic pathways based on defined profiles generated on the Cancer Genome Atlas database (p53, PI3K, ER, RTK, RAS, RAF, WNT, MYC, cell cycle, notch). Associations between ctDNA pathways alterations and tdEVs were tested in the overall population by multinomial logistic regression and corrected for significant clinical characteristics. Differences in liquid biopsy features between IBC and non-IBC subgroups were analyzed through Fisher's exact test. Results: Of the 355 MBC pts, 210 (62%) had HR+ BC, 61 (17%) had HER2+ BC, and 68 (20%) had triple-negative BC. Eighty-three (23%) had a diagnosis of IBC and had a numerically lower tdEV count. Also, lower tdEVs were detected in HER2+ BC as compared with HR+. Significantly higher tdEVs were observed among pts with lobular histology, liver, and bone metastases. CTC count was significantly associated with tdEV number. A matched plasma sample for ctDNA analysis was available for 175 pts (62 IBC and 113 non-IBC). In the overall population, SNVs in ER pathway were associated with intermediated/high levels of tdEVs (p=0.004 and 0.008). A similar association was observed for CNVs in the cell cycle pathway (p=0.008 and 0.007). Moreover, associations with ≥80 tdEVs were observed for PI3K SNVs and CNVs (p=0.039 and 0.004, respectively), RTK CNVs (p=0.023), and MYC CNVs (p=0.001). In multivariable analysis, clinical characteristics associated with higher tdEVs were lobular histology (p=0.014 for 20-79 and < 0.001 for ≥80) and bone metastases (p=0.019 for 20-79 and 0.002 for ≥80). When considering clinical variables of interest, only ER SNVs and MYC CNVs were significantly associated with intermediate (p=0.031) and high (p=0.022) tdEV counts, respectively. While the association with ER SNVs and cell cycle CNVs was significant both in the IBC and non-IBC subgroups, others were specific for a certain subgroup: higher tdEVs were significantly associated with PI3K SNVs only in non-IBC pts whereas the significant association with CNVs in PI3K and MYC pathways was observed only in pts with IBC. Conclusion: Detection of tdEVs was associated with particular genomic profiles. These alterations seem to be different in IBC further underlying a different biology of this BC subtype. Additional studies are needed to explore how to integrate different liquid-biopsy based biomarkers in the management of pts with MBC. Citation Format: Eleonora Nicolò, Lorenzo Gerratana, Lorenzo Foffano, Laura Munoz Arcos, Mara Serena Serafini, Maroua Manai, Letizia Pontolillo, Nadia Bayou, Elisabetta Molteni, Amanda Kaylan Strickland, Youbin Zhang, Paolo D’Amico, Andrew Davis, Jeannine Donahue, Huiping liu, William Gradishar, Ami Shah, Giuseppe Curigliano, Carolina Reduzzi, Massimo Cristofanilli. Association of tumor-derived extracellular vesicles with circulating tumor DNA alterations in metastatic breast cancer patients: exploring differences in inflammatory 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 PO3-06-05.

Abstract 7500: Distribution and prognostic significance of circulating tumor cells (CTCs) and tumor-derived extracellular vesicles (tdEVs) in patients (pts) with lobular metastatic breast cancer (MBC)

Abstract Background: Invasive lobular carcinoma (ILC) has distinctive clinical and molecular features compared with invasive ductal carcinoma (IDC). CTCs and tdEVs are independent prognostic factors in MBC, however, liquid biopsy studies focusing on ILC are to date scarce. Higher CTC levels have been observed in ILC than IDC. One study including 28 ILC pts suggested the use of higher CTC cutoff for prognosis stratification. The clinical significance of tdEVs in ILC is unexplored. This study aimed to assess differences in the distribution and prognostic value of CTCs and tdEVs between ILC and IDC. Methods: Blood samples were collected from 304 pts with MBC before starting a new line of therapy at Northwestern University (Chicago, IL) between 2016 and 2021 (NU16B06 trial). Blood was processed with the CellSearch® system. The ACCEPT software was applied to CellSearch® images to automatically enumerate CTCs and tdEVs. Association of CTCs and tdEVs with overall survival (OS) was tested in ILC and IDC pts. A count of CTCs ≥ 5 was considered high. The cutoff levels for tdEVs were < 20 (low), 20-79 (intermediate), and ≥ 80 (high), as previously reported. Additional exploratory cutoffs for CTCs (≥ 20, ≥ 50, ≥ 80, and ≥ 100) and tdEVs (based on quartiles of tdEV distribution in the overall population and ILC) were also evaluated. Results: Of the 304 pts, 47 had ILC while 257 had IDC. 56% of pts received first-line therapy. Median CTC count was 8 [interquartile range (IQR) 2-35] in ILC and 1 (IQR 0-8) in IDC pts (P <.001). A significantly higher median tdEVs count was observed in ILC (36; IQR 18-115) than in IDC (11; IQR 2-86) pts (P =.002). High levels of CTCs (≥5) were not associated with OS in ILC (P =.88), even when higher cutoffs (≥ 20, ≥ 50, and ≥ 80) were used. Only the detection of ≥ 100 CTCs was significantly associated with OS in ILC pts (median OS 36 vs 10 months; HR 3.4; P =.028). In contrast, the prognostic effect of CTCs ≥ 5 was strong in IDC and maintained for all cutoffs. Similarly, while the prognostic value for tdEVs was confirmed for IDC using both 20-80 and exploratory cutoffs (3-105 and 18-155), no association between tdEV levels and OS was observed in ILC regardless of the cutoffs used. Conclusion: ILC is associated with higher CTCs and tdEVs compared to IDC, probably due to the impaired cell-cell adhesion that characterizes ILC. Unlike IDC, the prognostic effect for the established cutoff of ≥ 5 CTC was not observed in ILC. A higher CTC cutoff could be considered for this subtype of BC. For tdEV no association with OS was observed, regardless of the cutoff used. These findings emphasize that ILC is a distinct entity also in the liquid biopsy features. Because of the low prevalence of ILC, research efforts should be directed at combining data from ILC pts to better characterize this subtype of BC and understand the reason behind the different associations with OS as compared to IDC. Citation Format: Eleonora Nicolo, Lorenzo Gerratana, Lorenzo Foffano, Laura Munoz-Arcos, Mara S. Serafini, Maroua Manai, Letizia Pontolillo, Nadia Bayou, Elisabetta Molteni, Amanda K. Strickland, Caterina Gianni, Youbin Zhang, Paolo D'Amico, Andrew A. Davis, Jeannine Donahue, Huiping Liu, William J. Gradishar, Ami N. Shah, Giuseppe Curigliano, Carolina Reduzzi, Massimo Cristofanilli. Distribution and prognostic significance of circulating tumor cells (CTCs) and tumor-derived extracellular vesicles (tdEVs) in patients (pts) with lobular metastatic breast cancer (MBC) [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 7500.

Abstract 3690: Monitoring prostate specific membrane antigen or androgen receptor expression on circulating stromal cells in advanced prostate cancer patients and their correlation with patient response

Abstract Background: Metastatic Prostate cancer (mPCa) mortality rates are high despite numerous treatment options against various mechanisms of action, including targeted therapies, i.e. prostate specific membrane antigen (PSMA)-targeted therapy (Pluvicto) or anti-androgen receptor (AR) (Enzulamide, Biculamide). Further, tumor biomarkers (i.e. PSMA and AR) can change over time and with resistance mechanisms that develop after treatments. This suggests that primary biopsies may not represent later PCa tumors necessitating a way to identify patients that may respond to later line therapies. Blood based biopsies can be used to monitor PCa treatment, which can include circulating tumor cells (CTCs) and the newly discovered cancer associated macrophage like cells (CAMLs), a cancer specific circulating phagocytic stromal cells. Interestingly, while PSMA & AR have been identified in CTCs, they have not been evaluated in CAMLs, nor have PSMA & AR expressions in CTCs & CAMLs been evaluated in anti-AR therapy settings. We measured CAMLs & CTCs in mPCa to evaluate their PSMA & AR expression, including in patients treated with anti-AR therapy. Methods: We evaluated CAMLs & CTCs in a multi-institutional prospective pilot study using n=30 mPCa patients with progressive disease, prior to starting a new line of therapy (T0). Whole peripheral blood (7.5mL) was filtered for CAMLs & CTCs and stained for PSMA (n=15) & AR (n=15). In addition, 15 patients were treated with anti-AR therapy as standard of care and responses by PET/CT were compared against AR expression. When possible, follow up samples (T1) were also procured. Results: CTCs were identified in 16% (n=5/30) of patients and CAMLs were identified in 96% (n=29/30), with 53% of patients having hyperengorged CAMLs ≥50 μm (n=16/30). CTCs in patients were not statistically significant for worse outcomes PFS HR= 0.1748, p=0.546 nor OS (HR= 1.303, p=0.865), nor were CAMLs prognostic for PFS or OS. However, patients with ≥50 μm CAMLs did have significantly worse PFS (HR= 5.9, CI95% 2.2-16.3, p=0.001) and worse OS (HR= 3.1, CI95% 1.3-7.1, p=0.016). Further, PSMA CAML/CTC expression was high in 60% (n=9/15) of patients and AR CAML/CTC expression was high in 53% (n=8/15). Of the n=15 patients who received anti-AR therapy after T0, high AR expressing CAMLs/CTCs (n=8/15) had a ~250% better mPFS of 10.3 months (mons) (progressing at 2.2-32.6 mons) vs low AR CAMLs/CTCs mPFS of 4 mons (progressing at 0.2-7.2 mons). Additional mOS analysis from T1 samples and 2-year survival is ongoing. Conclusion: We utilized liquid biopsies to monitor the expression of two common cell surface receptors (PSMA & AR) in CAMLs and CTCs in mPCa. Further, in a small subset of patients treated with AR therapy, high AR CTC/CAML expression appeared to correlate with better response rates, though larger prospective studies are needed. Citation Format: Dimpal M. Kasabwala, Raymond C. Bergan, R. Katherine Alpaugh, Daniel C. Danila, Tuan L. Chuang, Brenda Y. Hurtado, Daniel L. Adams. Monitoring prostate specific membrane antigen or androgen receptor expression on circulating stromal cells in advanced prostate cancer patients and their correlation with patient response [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 3690.

Dedicated financial hardship screening adds value to routine distress screening among gynecologic cancer patients

ObjectivesTo evaluate existing distress screening to identify patients with financial hardship (FH) compared to dedicated FH screening and assess patient attitudes toward FH screening. MethodsWe screened gynecologic cancer patients starting a new line of therapy. Existing screening included: (1) Moderate/severe distress defined as Distress Thermometer score ≥ 4, (2) practical concerns identified from Problem Checklist, and (3) a single question assessing trouble paying for medications. FH screening included: (1) Comprehensive Score for Financial Toxicity (COST) tool and (2) 10-item Financial Needs Checklist to guide referrals. FH was defined as COST score < 26. We calculated sensitivity (patients with moderate/severe distress + FH over total patients with FH) and specificity (patients with no/mild distress + no FH over total patients with no FH) to assess the extent distress screening could capture FH. Surveys and exit interviews assessed patient perspectives toward screening. ResultsOf 364 patients screened for distress, average age was 62 years, 25% were Black, 45% were Medicare beneficiaries, 32% had moderate/severe distress, 15% reported ≥1 practical concern, and 0 reported trouble paying for medications. Most (n = 357, 98%) patients also completed FH screening: of them, 24% screened positive for FH, 32% reported ≥1 financial need. Distress screening had 57% sensitivity and 77% specificity for FH. Based on 79 surveys and 43 exit interviews, FH screening was acceptable with feedback to improve the timing and setting of screening. ConclusionsDedicated FH screening was feasible and acceptable, but sensitivity was low. Importantly, 40% of women with FH would not have been identified with distress screening alone.

Incidence of Second Primary Malignancies in Medicare-Insured Patients in the US with Triple-Class Exposed Relapsed/Refractory Multiple Myeloma

Background As therapeutic advances have increased life expectancy for patients (pts) with relapsed/refractory (RR) multiple myeloma (MM), second primary malignancies (SPMs) have become an increasingly important safety consideration. Prior studies have demonstrated that treatment with alkylators, autologous stem cell transplantation, and immunomodulatory drugs (IMiDs), specifically lenalidomide, are associated with increased risk of SPM. Pts who are triple-class exposed (TCE), defined as prior exposure to an IMiD, a proteasome inhibitor (PI), and an anti-CD38 monoclonal antibody (mAb), represent an increasingly large subgroup of RRMM pts. The objective of this study was to describe the incidence and characteristics of SPMs in Medicare-insured pts with TCE RRMM initiating a new line of therapy (LOT). Methods Adult pts with an incident diagnosis (Dx) of MM (≥2 outpatient Dx 30-365 days apart OR ≥1 inpatient Dx AND 6 months of continuous eligibility prior to initial Dx) during the study period (Nov 14, 2006-Dec 31, 2020) who were TCE (≥1 claim each for an IMiD, a PI, and an anti-CD38 mAb) were selected from the Center for Medicare and Medicaid Services Chronic Conditions Data Warehouse (TCE pts were assumed to have RRMM based on exposure). The first LOT after TCE was defined as the index LOT and the associated date of initiation was defined as the index date. Pts with SPMs prior to the index date were excluded. SPMs were identified based on having ≥2 outpatient Dx of SPM (of the same cancer type) 30-365 days apart OR ≥1 inpatient Dx of SPM. Dx of SPM included Dx of invasive malignancies or myelodysplastic syndromes (MDS), excluding MM, Waldenström macroglobulinemia, plasma cell leukemia, non-melanoma skin cancers, or primary bone malignancies that were preceded by a Dx of bone metastases. The incidence of SPM was calculated per 100 person years (PY) of follow-up, considering only the first SPM for each pt. Cumulative incidence of SPM (with death as a competing risk) was also calculated. For pts who experienced SPM, overall survival (OS) and measures of healthcare resource utilization (HRU) and costs (in 2021 USD, on a per patient per month [PPPM] basis) were calculated. Results A total of 3,088 TCE RRMM pts were identified, of whom 989 had no evidence of SPM prior to the index date (Table). These 989 pts had a mean age of 75.2 years, a mean of 2.9 prior LOTs and a mean of 3.1 years since MM Dx. Over a median follow-up of 7.1 months, 166 pts (19.3 per 100 PY) experienced an SPM, including 93 (10.8 per 100 PY) with a solid tumor and 73 (8.5 per 100 PY) with a hematologic malignancy. The latter included 27 (3.1 per 100 PY) with acute myeloid leukemia (AML) and 18 (2.1 per 100 PY) with MDS. The cumulative incidence of SPM (95% confidence interval [CI]) at 12, 24, and 36 months was 15.2% (12.8-17.9%), 19.7% (16.8-22.8%), and 23.8% (20.2-27.6%), respectively (Figure). Median (95% CI) OS from SPM Dx was 7.9 months (5.4-10.9). Kaplan-Meier estimated probability of survival (95% CI) at 12, 24, and 36 months following SPM Dx was 40.3% (31.6-48.9%), 27.6% (18.6-37.4%), and 9.5% (2.1-23.8%), respectively. Mean (95% CI) total costs after SPM were $22,514 ($19,105-$26,404) PPPM. Conclusions The incidence of SPM in Medicare-insured TCE RRMM pts is high. Many SPMs in these pts, such as AML, are life-threatening and may interfere with or prevent MM treatment. Pts with SPMs have poor survival and high HRU and costs. With increasing OS for RRMM pts due to therapeutic advancements, there is a need for effective treatments that are not associated with increased risk of SPMs.

Health Outcome Preferences Among Older Adults with Multiple Myeloma Undergoing Systemic Therapy

Introduction: Multiple Myeloma (MM) is the second most common hematologic malignancy in the US; over half of patients are ≥70y at diagnosis. Prior studies have shown that treatment preferences of older adults with cancer vary based on burden/intensity of current treatment and its impact on functional and cognitive well-being in addition to anticipated survival. However, no such studies exist among older adults with MM. We sought to understand health outcome preferences in a cohort of older adults with MM. Methods: Using the Cancer and Aging Resilience Evaluation in Hematologic Malignancies Registry (NCT05556928), a single institution prospective observational study of older adults with hematologic malignancies undergoing systemic therapy, we identified patients diagnosed with multiple myeloma at age ≥50y who had undergone a geriatric assessment (GA) within 30 days of initiating a new line of therapy (1 st to 5 th line).Treatment preference was assessed using a 9-item health outcome preference attitude scale (Case et al Patient Educ Couns 2013), rating self-reported agreement with statements related to health outcomes on a Likert scale. Frailty was assessed using a deficit accumulation method as previously described (Giri S et al J Am Geriatr Soc 2023) We measured the proportion of patients reporting other outcomes being “as important” or “more important” than survival and compared the response between younger (&amp;lt;70y) and older (≥70y) adults. Subsequently, we built proportional odds models to study the factors associated with a greater prioritization of outcomes other than survival. All p values were two sided and the level of significance was chosen at 0.05. Results: Of the 228 patients initiating a new line of therapy between 01/2022 to 4/2023, 104 (47%) underwent treatment preference assessment. The median age at enrollment was 65y with 33% ≥70y; 62% were males, 57% whites; 19% had ISS stage 3 disease; 28% were frail on the CARE frailty index. In the younger (age &amp;lt;70y) vs older (age ≥70y) patients, 32% vs 77% agreed/strongly agreed with: “I would rather live a shorter life than lose my ability to take care of myself”; and 54% vs 79% agreed/strongly agreed with: “It is more important to me to maintain my thinking ability than to live as long as possible”. In multivariable models, age but not frailty, sex, race or disease stage were associated with health outcome prioritization other than survival. Each 1y increase in age was associated with and 8% (Odds Ratio 1.08; 95% CI 1.03-1.13; p value=0.001) and 4% (OR 1.04; 95% CI 1.0-1.09; p value=0.04) increased odds of rating functional independence and cognition respectively as more important than survival. Conclusions: Three out of four older adults (age&amp;gt;70y) with MM rated other outcomes (particularly physical function and cognitive ability) as being more important than survival. Eliciting which outcomes are the most important for older patients can help define treatment goals and improve shared decision-making. Further, interventions focusing on preserving physical and cognitive function need to be tested in this population.

Efficacy of Chemo-Free Combination Therapy with BRAF Inhibitor and Rituximab in Classic Hairy Cell Leukemia: Insights from the French Experience

Background: Hairy cell leukemia (HCL) is a rare form of leukemia. The introduction of purine analogs has revolutionized its prognosis, leading to a life expectancy closer to that of the general population. However, patients experience relapses and require other treatment options. The BRAF V600E mutation is present in 80-100% of patients with HCL, which has prompted the use of BRAF inhibitors (vemurafenib or dabrafenib) in this condition. Recently, the combination of vemurafenib with rituximab has shown efficacy with durable responses in relapsed patients. Here, we present, for the first time, real-life data on the combination of a BRAF inhibitor with rituximab through a retrospective study involving 9 French centers. Data collection was completed by July 1, 2023. Results: We collected data from 17 patients with a male-to-female ratio of 13:4; the median age was 69 years (38-90), and 6 patients were aged over 75. The median number of previous treatments was 4 (0-7), and 3 patients were treatment-naive because they were deemed ineligible for purine analogs based on age or performance status. All 14 relapsed patients had previously received purine analogs once or multiple times (1-3). The median progression-free survival (PFS) after purine analogs was 48 months, and the median PFS after the last line of therapy was 24 months. Five patients were exposed to moxetumumab pasudotox, and 3 patients received single-agent vemurafenib previously. The BRAF V600E mutation was tested and positive for 16 patients. In our cohort, 13 patients received a combination of vemurafenib with rituximab (V+R), and 4 patients received a combination of dabrafenib with rituximab (D+R). All patients received the same regimen (Tiacci, NEMJ 2021), which included an induction phase (V+R or D+R for 8 weeks) followed by rituximab consolidation (4 injections every 15 days), except for one patient who received a rituximab sequence followed by vemurafenib. At the time of analysis, 15 out of 17 patients had completed the treatment, and the remaining 2 had completed the induction phase. Fourteen patients initiated treatment at the standard dose (960 mg bid for vemurafenib and 150 mg bid for dabrafenib), and 3 patients at a reduced dose (240-480 mg bid for vemurafenib). Toxicity of any grade was reported in 15 out of 17 patients, with 3 of them experiencing grade 3-4 toxicity. Skin toxicity was the most frequent, recorded in 12 patients (grade 1-2), leading to temporary treatment interruption in 2 patients and dose reduction in 6 patients. Other toxicities included musculoskeletal, hepatic, hematological, and cardiac, with only one patient experiencing a grade 2 infection during treatment. No secondary cancers were reported during or after treatment. Treatment was discontinued due to toxicity in 5 patients, with 4 of them resuming treatment later. Eight patients required a dosage reduction, with a median final vemurafenib dosage of 480 mg bid. At the end of treatment, 14 patients achieved a complete hematological response, and 1 patient achieved a partial response. Among the 9 patients with early response data, the median time for platelet recovery was 15 days, and for neutrophil recovery, it was 14 days. End-of-treatment bone marrow aspiration and/or biopsy was performed for 8 patients, showing a complete response in 7 patients. With a median follow-up of 12 months (4-56), only 2 patients had progressed, and as of the last update, no patients had died, and the 2 relapsed patients achieved a complete response after a new line of therapy. Conclusion: Despite a limited median follow-up of 12 months, the combination of a BRAF inhibitor with rituximab proves to be an effective regimen in heavily treated patients with HCL, achieving a 100% overall response rate. Our study confirms a rapid hematological response and an acceptable toxicity profile, even in elderly patients. The most frequent toxicity observed was cutaneous toxicity, mainly grade 1-2, and it never led to a definitive treatment discontinuation. A comparison of the two BRAF inhibitors in terms of efficacy or toxicity cannot be established due to the small sample size of patients treated with dabrafenib. Lastly, the combination of rituximab with vemurafenib or dabrafenib appears to be an interesting option in frontline treatment for patients ineligible for purine analogs.

Information needs when deciding to start a new line of therapy for advanced cancer: Are patients, caregivers, and oncologists aligned?

315 Background: Effective decision-making on whether to start the next line of therapy for advanced cancer requires comprehensive, tailored information aligned with needs and preferences of patients and caregivers. Our study aimed to compare patient and caregiver information needs to information that oncologists consider and share when discussing prognosis before starting a new line of therapy. Methods: Our study used Latent Dirichlet Allocation (LDA)-based topic modeling, a text mining method, to extract topics embedded in semi-structured interview transcripts from patient and caregiver (n=20) and oncologist (n=10) participants. Transcripts were collected as part of a larger study to design an interface for a prognostic tool. Patients and caregivers were asked to identify information needs when deciding to start a new line of therapy. Oncologists were asked through critical incident technique to recall a recent patient encounter and, with probing questions, describe information they consider and how they communicate expected survival time. Two members of the study team identified extracted topics using an interactive, intertopic distance map, then compared topics between patient/caregiver and oncologist datasets. Results: Results revealed 6 distinct topics from patients and caregivers and 6 distinct topics from oncologists that we grouped into 3 overall themes (Table 1). While topics across both participant groups were similar, two notable differences were found in patient and caregiver interviews: 1) the desire for information about support-related resources, which was not noted by oncologists, and 2) topics included keywords like “helpful” and “clear” to describe information needs, highlighting the importance of how information is presented by oncologists. Conclusions: LDA-based topic modeling was useful to identify topics from transcripts, highlighting information needs and what is shared when discussing prognosis and starting a new line of therapy. Limitations include use of self-reported descriptions and lack of actual conversations between patients and oncologists. However, findings show the ongoing gap in communication about support-related resources when discussing prognosis. Opportunities exist to enhance communication about prognosis and promote access to resources using decision support tools.[Table: see text]

Understanding testing for and treatment of homologous recombination repair (HRR)-mutated metastatic castrate-resistant prostate cancer (mCRPC): A quality initiative by Integra Connect PrecisionQ.

581 Background: In May of 2020, the approval of two Poly (ADP-ribose) polymerase inhibitors (PARPi) changed the landscape for treatment among patients (pts) with HRR mutations (HRRm) in mCRPC. The University of Pittsburgh Medical Center (UPMC) conducted a Quality Initiative (QI) with Integra Connect PrecisionQ to assess the rates of HRR testing, HRR positivity, and PARPi use in HRRm patients with mCRPC. This QI included clinical interventions to optimize testing and treatment in these patients. We aim to show the improvement in HRR testing and rates of treatment with PARPi after implementation of the QI in patients with HRRm mCRPC at UPMC. Methods: Using the de-identified Integra Connect PrecisionQ database, 223 UPMC pts with mCRPC were selected by medical chart curation as the baseline group. Patients in this group had received treatment between 5/1/2020 to 9/30/2021 and were confirmed as mCRPC. The baseline data was reviewed with UPMC clinical leadership, discussed at a physician roundtable, and shared among providers. Post-baseline, we evaluated 152 mCRPC pts who started a new line of therapy between 1/1/2022 to 12/31/2022 to assess HRR testing rates and use of PARPi in eligible mCRPC pts. The presence of one or more HRR genes was used to determine testing rates. Descriptive analyses were performed and a two-proportion z-test was used for comparisons of HRR testing in patients with mCRPC and treatment with a PARPi in HRRm mCRPC pts. Results: The average age at diagnosis was 67 years, 47% of patients had a Gleason score of &gt; = 8, and 62% were stage IV. The rate of HRR testing at baseline was 52% (116 of 223). The results post-baseline and intervention showed an increase in HRR testing to 69% (105 of 152) of mCRPC patients who started a new line of therapy in 2022 (p &lt; 0.01). At baseline, 60% (21 of 35) of HRRm pts were treated with a PARPi after prior NHA treatment, compared to 68% (19 of 28) post-baseline and intervention (p &gt; 0.05). Among all HRR mCRPC tested pts, there was a 30.9% (84/272) positivity rate, of which 11.4% were BRCA1/2 positive (30/262) and 10.5% were ATM positive (26/247). Not all patients tested for HRR were tested for all genes. Conclusions: This Quality Initiative to improve testing and identification of HRR mutations in patients with mCRPC led to a 33% relative increase in HRR testing, demonstrating how QI programs can transform care and move the field toward individualized, precision medicine.

Design of an interface to communicate artificial intelligence-based prognosis for patients with advanced solid tumors: a user-centered approach.

To design an interface to support communication of machine learning (ML)-based prognosis for patients with advanced solid tumors, incorporating oncologists' needs and feedback throughout design. Using an interdisciplinary user-centered design approach, we performed 5 rounds of iterative design to refine an interface, involving expert review based on usability heuristics, input from a color-blind adult, and 13 individual semi-structured interviews with oncologists. Individual interviews included patient vignettes and a series of interfaces populated with representative patient data and predicted survival for each treatment decision point when a new line of therapy (LoT) was being considered. Ongoing feedback informed design decisions, and directed qualitative content analysis of interview transcripts was used to evaluate usability and identify enhancement requirements. Design processes resulted in an interface with 7 sections, each addressing user-focused questions, supporting oncologists to "tell a story" as they discuss prognosis during a clinical encounter. The iteratively enhanced interface both triggered and reflected design decisions relevant when attempting to communicate ML-based prognosis, and exposed misassumptions. Clinicians requested enhancements that emphasized interpretability over explainability. Qualitative findings confirmed that previously identified issues were resolved and clarified necessary enhancements (eg, use months not days) and concerns about usability and trust (eg, address LoT received elsewhere). Appropriate use should be in the context of a conversation with an oncologist. User-centered design, ongoing clinical input, and a visualization to communicate ML-related outcomes are important elements for designing any decision support tool enabled by artificial intelligence, particularly when communicating prognosis risk.

Survivorship transitions in blood cancer: Identifying experiences and supportive care needs for caregivers.

Survivorship care often refers to continued healthcare after cancer treatment. Jacobsen and colleagues advocated to expand this to include patients on extended treatments and maintenance/prophylactic therapies, recognizing the care continuum as more complex. Transitions of care for individuals diagnosed with a blood cancer can be complicated. We sought to better understand blood cancer caregivers' experiences as their diagnosed family member encountered "survivorship transitions" across the continuum. We conducted semi-structured interviews with adults caring for a parent or a child with a blood cancer. Caregivers were segmented into survivorship groups based on two transitional contexts: (1) when patients transitioned to a new line of therapy (active treatment or maintenance therapy); (2) when patients ended treatment. We conducted a thematic analysis and triangulated findings to compare transitional experiences. Caregivers in both groups reported experiencing a "new normal," which included personal, relational, and environmental adjustments. Caregivers in the treatment transitions group (n = 23) also described uncertainty challenges (e.g., losing their "safety net") and disrupted expectations (e.g., feeling "caught off guard" by challenges). Whereas caregivers in the end-of-treatment transitions group (n = 15) described relief coupled with worry (e.g., feeling hopeful yet worried). Survivorship transitions for caregivers are riddled with challenges that include difficult readjustments, uncertainty/worry, and unmet expectations. While there seems to be a cohesive experience of "survivorship transitions," each transition group revealed nuanced distinctions. Tailored supportive resources are needed for caregivers throughout survivorship transitions.

Utilizing a two-step frailty assessment strategy in older adults with multiple myeloma (MM): A decision curve analysis.

8061 Background: The International Myeloma Working Group Frailty Index (IMWG-FI) has been shown to predict risk of toxicity and mortality in older adults with MM (Palumbo et al., Blood 2015). However, IMWG-FI requires a geriatric assessment (GA) that is not routinely done in clinical practice due to time constraints. A simplified frailty index (SFI; Facon et al., Leukemia 2020) has been proposed as an alternative using ECOG PS as a proxy to functional status. We previously reported a moderate concordance between these two frailty indices (Kappa statistic 0.50; Gahagan et al., ASH 2022). Here, we examined if SFI can be utilized as a screening tool to identify patients who would benefit from a formal GA and frailty assessment. We hypothesized that a two-step approach would minimize the need for unnecessary GAs, while saving time in clinical practice. Methods: For this analysis, we included patients ≥50yo with newly diagnosed (ND) or Relapsed/Refractory (RR)-MM at a single institution initiating a new treatment regimen (1st to 6th line) who are enrolled in a prospective registry (NCT05556928). All patients underwent a GA prior to a new line of therapy. ECOG PS and comorbidities were abstracted from medical records. We calculated IMWG-FI and SFI using published methods. Sensitivity, specificity along with their 95% CI were calculated for both SFI and IMWG-FI, using published SFI cutpoints. Lastly, we used decision curve analysis (DCA) as described by Vickers et al. to calculate the benefit of frailty screening using SFI for detection of non-frail patients and avoiding unnecessary GAs. We assumed that reasonable threshold probabilities were 0.25 and 0.33 respectively indicating that missing an unfit patient was 3 and 2 times worse than exposing a fit patient to an unnecessary GA (odds of 1:3 and 1:2 respectively). We quantified the net benefit (NB) of this two-step frailty assessment versus GA-for-all in terms of net reduction in unnecessary GAs. Results: A total of 146 adults with MM (49 ND-MM, 51 pre-transplant, and 46 RR-MM) starting a new line of therapy between 8/2020-1/2022 were included in this study. The median age was 62 (IQR 57-70) with 53% males and 36% blacks. The distribution by IWMG-FI was 43% fit, 32% intermediate-fit, and 25% frail. Using SFI, 32% of patients were frail. Using a cutpoint of ≥2, SFI as a screening tool had a sensitivity of 89.2% (95% CI 75-96%) and a specificity of 65% (95% CI 56% to 73%). DCA showed that selecting candidates for GA based on a two-step strategy (SFI followed by IMWG-FI) led to an absolute 40-45% reduction in the number of unnecessary GAs without missing any frail patients. Conclusions: Our results suggest that using a two-step frailty assessment strategy of SFI as a screening tool followed by confirmation with IMWG-FI reduces the need for unnecessary GAs by 40-45% and may be more suitable for integration in busy oncology practice.

Understanding testing for and treatment of homologous recombination repair (HRR)-mutated metastatic castrate-resistant prostate cancer (mCRPC): A quality initiative by Integra Connect (IC) PrecisionQ.

e17052 Background: In May of 2020, the approval of two Poly (ADP-ribose) polymerase inhibitors (PARPi) changed the landscape for treatment among patients (pts) with HRR mutations (HRRm) in mCRPC. The University of Pittsburgh Medical Center (UPMC) conducted a quality initiative (QI) with IC PrecisionQ to assess the rates of HRR testing, HRR positivity, and study the rates of PARPi use in HRRm patients with mCRPC. This QI included clinical interventions to optimize testing and treatment in these patients. We aim to show the improvement in HRR testing and rates of treatment with PARPi after implementation of the QI, in patients with HRRm mCRPC at UPMC. Methods: Using the de-identified IC PrecisionQ database, 223 UPMC pts with mCRPC were selected by medical chart curation as baseline group. Patients in the baseline group had received treatment between 5/1/2020 to 9/30/2021 that were confirmed as mCRPC. The baseline data was reviewed with UPMC clinical leadership, discussed among a physician roundtable, and HRR testing rates were shared among providers. Post-baseline, we evaluated 152 mCRPC pts who started a new line of therapy between 1/1/2022 to 12/31/2022 to assess HRR testing rates and use of PARPi in eligible mCRPC pts. The presence of one or more HRR genes was used to determine testing rates. Descriptive analyses were performed and a two-proportion z-test was used for comparisons of HRR testing in patients with mCRPC and treatment with a PARPi in HRRm mCRPC pts. Results: The average age at diagnosis was 67 years, 47% of patients had a Gleason score of &gt; = 8, and 62% were stage IV. The rate of HRR testing at baseline was 52% (116 of 223). The results post baseline and intervention showed an increase in HRR testing to 69% (105 of 152) of mCRPC patients who started a new line of therapy in 2022 (p &lt; 0.01). At baseline, 60% (21 of 35) of HRRm pts were treated with a PARPi after prior NHA treatment compared to 68% (19 of 28) post baseline and intervention (p &gt; 0.05). Among all HRR mCRPC tested pts, there was a 30.9% (84/272) positivity rate, of which 11.4% were BRCA1/2 positive (30/262) and 10.5% were ATM positive (26/247). Not all patients tested for HRR were tested for all genes. Conclusions: This quality initiative to improve testing and identification of HRR mutations in patients with mCRPC led to a 33% relative increase in HRR testing. Quality initiative programs are critical to transforming cancer care and moving the field closer toward individualized, precision medicine.

Prognostic value of tumor-derived extracellular vesicles and circulating tumor cells in metastatic breast cancer (BC): A focus on inflammatory BC.

1098 Background: Circulating tumor cells (CTCs) are an independent prognostic factor in metastatic breast cancer (MBC). The prognostic value of CTCs and the optimal cutoff for patients (pts) with inflammatory breast cancer (IBC), one of the most aggressive types of BC, has not been fully established. Recent evidence showed the complementary prognostic value of tumor-derived extracellular vesicles (tdEVs) to CTCs in MBC. The significance of tdEVs in IBC is unexplored. This study aimed to assess the prognostic value of CTCs and tdEVs in metastatic IBC. Methods: This study retrospectively analyzed 308 pts with MBC enrolled at Northwestern University (Chicago, IL) before starting a new line of therapy between 2016 and 2021 (NU16B06 trial). Blood samples were processed for CTCs using the CellSearch system. We applied the open source ACCEPT software to archived CellSearch images to enumerate CTCs and tdEVs. TdEVs cutoff levels were &lt;20 (low), 20-79 (intermediate), and ≥80 (high), as previously reported. The association of CTCs and tdEVs with overall survival (OS) was tested in the overall population (OvP) and IBC pts. Results: Of the 308 pts, 69 were diagnosed with IBC. 51% of pts received first-line therapy. CTCs enumerated by ACCEPT were strongly correlated with manual count (r=0.86) and hence used for this analysis. Median CTC count was 1 [interquartile range (IQR) 0-7] in IBC pts and 3 (IQR 0-14) in non-IBC (p=0.11). A significantly lower median tdEVs count was observed in IBC (7; IQR 3-45) than in non-IBC (22; IQR 4-137) pts (p=0.03). In IBC, higher CTC and tdEV counts were seen in the triple negative subtype (p=0.03) and non-visceral involvement (p=0.02), respectively. In the OvP median OS (mOS) was worse among pts with ≥5 CTCs (HR 2.6; p=0.001) and with elevated tdEVs (HR 3.3; p&lt;0.001). Only tdEVs were independently associated with poorer OS in multivariable analysis. In pts with &lt;5 CTCs there was a stepwise decrement in OS with increased tdEVs count (p=0.3); in pts with ≥5 CTCs, elevated tdEVs levels were associated with significantly worse OS (p=0.03). IBC pts with ≥5 CTCs had shorter mOS (8 vs 47 months; HR 3.6; p&lt;0.001); this association was weaker using ≥1 as CTC cutoff (HR 2.4; p=0.01). OS was adversely associated with increasing tdEVs levels (33 vs 23 vs 7 months for low, intermediate, and high subgroups, respectively; HR 3.7; p=0.001). Furthermore, elevated tdEVs were associated with shorter mOS in pts with ≥1 (p=0.055) and ≥5 CTCs (p=0.6). Among pts with &lt;5 CTCs no significant difference emerged among tdEVs subgroups (p=0.6). Conclusions: This study confirmed the strong prognostic significance of CTCs and tdEVs in MBC, including IBC. Pts with IBC had fewer CTCs and tdEVs compared to non-IBC, probably due to the predominant lymphatic spread of IBC. tdEVs offer the possibility to better define prognosis of IBC pts. Further studies are needed to evaluate their complementarity to CTCs.

Baseline tumor growth rate highlights the heterogeneity of well differentiated gastroenteropancreatic neuroendocrine tumors and predicts for increases in Ki67 index over time.

Refined risk stratification for gastroenteropancreatic neuroendocrine tumors (GEP-NETs) has the potential to improve comparisons of study populations across clinical trials and facilitate drug development. Tumor growth rate (TGR) is a radiological metric with demonstrated prognostic value in well differentiated grade 1 and 2 (G1-2) GEP-NETs, but little is known about TGR in G3 NETs. In this retrospective study of 48 patients with advanced G1-3 GEP-NET, we calculated baseline TGR (TGR0 ) from radiological images of metastases acquired prior to first-line therapy and evaluated its association with disease characteristics and outcomes. The median pretreatment Ki67 proliferation index for G1-3 tumors combined was 5% (range = 0.1%-52%) and median TGR0 was 4.8%/month (m) (range = 0%-45.9%/m). TGR0 correlated with pretreatment Ki67 across G1-3 pooled and within G3 GEP-NET. Patients with higher TGR0 (>11.7%/m) tumors, which were primarily G3 pancreatic NETs, exhibited decreased time to first therapy (median, 2.2 vs. 5.3 months; p = .03) and shorter overall survival (median, 4.1 years vs. not reached; p = .003). Independent of therapies given, higher TGR0 GEP-NETs experienced a greater incidence of Ki67 increase (100 vs. 50%; p = .02) and greater magnitude of Ki67 change (median, 14.0 vs. 0.1%; p = .04) upon serial biopsy. Importantly, TGR0 , but not grade, predicted for future Ki67 increase in this series. Given the heterogeneity of well differentiated GEP-NETs, future clinical trials may benefit from stratification for TGR0 , particularly in G1-2 tumors, in which TGR0 does not correlate with Ki67. TGR0 has the potential to noninvasively identify patients with previously undiagnosed grade progression and those in whom more or less frequent monitoring may be appropriate. Additional research is needed to determine the prognostic and predictive value of TGR0 in larger and more homogeneously treated cohorts, and to ascertain if post-treatment TGR has value in previously treated patients starting a new line of therapy.

Cut-off Analysis of HLA-A and HLA-B/C Expression as a Potential Prognosticator of Favorable Survival in Patients With Metastatic Breast Cancer.

Loss of differentiation of breast cancer cells in association with a down-regulated class I human leukocyte antigen (HLA) expression can lead to proliferation unhampered by cytotoxic T lymphocytes, which has been proven to be of prognostic relevance. The objective of this study was to determine the levels of HLA-A and HLA-B/C expression in metastatic breast cancer (MBC) cells and their usefulness for predicting 5-year survival. This prospective double-blinded cohort study analyzed patients starting a new line of therapy for MBC. RT-qPCR was used to determine the levels of HLA-A and B/C expression in MBC cells and the mRNA-based tumor intrinsic subtype. Two receiver operating characteristic curves (ROC) were constructed in order to determine whether HLA-A and HLA-B/C expression levels can be used for predicting 5-year survival. Youden J points, and sensitivity and specificity optimized cut-off points were determined for both ROC curves. We enrolled 34 patients. The ROC curve for HLA-B/C had the highest AUC compared to HLA-A (0.55 vs. 0.42). High levels of HLA-A and HLA-B/C expression (40-ΔΔCT of 33.5 and 31.9, respectively) were highly specific (reaching 87.5% for HLA-A and even 100% specificity for HLA-B/C) yet insensitive for five-year survival in our study. High expression of certain class I HLA molecule subtypes by MBCs, in particular high HLA-A or B/C expression by MBC cells seems very specific in predicting the 5-year survival. We determined cut-off values for these HLA molecule clusters with high specificity, which might help identify patients with a favorable prognosis as prognosticators of a 5-year overall survival if their sensitivity is improved in larger prospective cohorts.

Abstract P2-26-06: Association between CK+/CD45+ circulating tumor cells (CTCs) and circulating tumor DNA (ctDNA) alterations in advanced breast cancer patients

Abstract Background: Circulating tumor cells (CTCs) in breast cancer (BC) are commonly defined as epithelial cells (EPCAM and cytokeratin (CK) positive), lacking the universal blood cell marker CD45. Nonetheless, CTCs expressing both CK and CD45 (= dual-positive, DP cells) can be observed in the blood of cancer patients. Early evidence suggests that DP cells might derive from the fusion of tumor cells and macrophages, and we have previously demonstrated that they present aberrant genomes and are associated with worse prognosis in BC [1,2]. Here, to further investigate the mechanisms/pathways underlying their presence, we analyzed the association between DP cells and circulating tumor DNA (ctDNA) alterations. Methods: Blood samples were collected from patients with advanced BC (aBC), before starting a new line of therapy. All patients were enrolled in a prospective clinical trial. For CTC and DP cells analysis, 7.5 ml of blood collected in CellSave® tubes was processed with the FDA-approved CellSearch® platform (positivity cutoffs were ≥1 cell for DPcells and ≥5 cells for CTCs). For ctDNA analysis, plasma was collected from Streck stabilizing tubes and analyzed with the Guardant360™ NGS platform for the detection of somatic single nucleotide variants (SNVs), insertions/deletions (indels), gene fusions/rearrangements and copy number variations (CNVs), which were then classified into pathways based on previously defined profiles generated on the Cancer Genome Atlas database (RTK, RAS, RAF, MEK, NRF2, ER, WNT, MYC, P53, cell cycle, notch, PI3K). Associations between ctDNA-detected gene alterations and circulating cell types were analyzed through chi square test, while mutant allele frequency (MAF) and number of detected alterations (NDA) were tested by Mann Whitney test. Results: We analyzed blood samples from 169 patients with luminal-like (n=80), HER2+ (n=34) and triple-negative (n=52) aBC. DPcells were detected in 85 patients (50.3 %, range 0-53), of which 40 (47 %) were CTC-positive and 45 (53%) CTC-negative. Somatic ctDNA alterations were detected in all analyzed samples. In the overall population, the presence of ≥1 DPcell was associated with SNVs in the cell cycle pathway (p = 0.043), a numerically higher incidence was also observed for CNVs in this pathway. SNVs and CNVs in the cell cycle pathway were associated with CTCs ≥ 5 as well (p = 0.005 and p = 0.003, respectively). Moreover, associations with CTCs ≥ 5 were observed for RTK SNVs and CNVs (p = 0.041 and p = 0.046, respectively), PI3K SNVs and CNVs (p = 0.006 and p = 0.007, respectively), MYC SNVs and CNVs (p = 0.042). No associations were observed in terms of MAF and NDA. In the luminal-like subgroup an association was highlighted for CNVs in the cell cycle pathway, p = 0.038. CTCs ≥ 5 were associated with PI3K SNVs (p = 0.031). In the triple-negative subgroup DPcells were associated with SNVs in the RAF pathway (p = 0.041), whereas CTCs ≥ 5 were associated with PI3K SNVs and CNVs (p = 0.044 and p = 0.024, respectively) and RTK SNVs (p = 0.008). In the HER2 positive subgroup, a higher MAF and number of detected SNVs was observed for samples with ≥1 DPcell (p = 0.0286 and p = 0.0099, respectively). Conclusions: The study analyzed ctDNA features associated with canonical and CK+/CD45+ CTCs, showing differential gene alteration profiles. Cell cycle pathway SNVs were common in both CTC populations, while other pathways (RTK, PI3K, MYC and RAF) were significantly altered in a mutually exclusive pattern. These results suggest that DPcells might have a different biological meaning compared to canonical CTCs. More studies need to be conducted to better characterize this understudied CTC subpopulation and understand their specific contribution to cancer progression.

Abstract P4-07-24: Circulating tumor cells enumeration and Health Related Quality of Life of patients treated with first-line chemotherapy for HER2 negative metastatic breast cancer

Abstract Background: In patients with metastatic breast cancer (mBC), Circulating Tumor Cells (CTC) counts have a strong prognostic impact on progression free survival (PFS) and overall survival (OS). Changes 4 weeks after the start of a new line of therapy, inform on treatment efficacy. Despite improvements in systemic treatment, metastatic BC remains mainly uncurable with alteration of health-related quality of life (HRQOL) during the course of the disease. The aim of this work was to assess impact of clinical factors and biological factors as CTC on HRQOL. Methods: The French cohort COMET is a prospective study including first line HER2 negative patients receiving weekly paclitaxel and bevacizumab according to EMA approved combination. The aim of this cohort was to evaluate clinical, biological and radiological parameters associated with patients’ outcome (CTC, CEC, serum markers, ctDNA, pharmacogenomic polymorphisms, metabolomic parameters, visceral fat assessed by initial CTscan, serum estradiol level, and quality of life). HRQOL was assessed at baseline, at every cycle until progression and then every 3 months up to death using the EORTC QLQ-C30 questionnaire and its breast cancer specific module, the EORTC QLQ-BR23. Five dimensions of HRQOL were analyzed for the primary analyses: Global health status (GHS), physical functioning (PF), Emotional functioning (EF), fatigue (FA) and pain (PA). Time until definitive deterioration (TUDD) in HRQOL was defined as the interval between inclusion and the first decrease in HRQOL score ≥ 5 compared to baseline HRQOL score with no further improvement or in case of death. CTC counts were determined using the standard CellSearch system [Menarini Silicon Biosystems]. Results: Out of 510 patients included in COMET study, 432 patients with available HRQOL data were analyzed in this study. At baseline, patients reported a mean score for GHS of 57.6 (SD=22.7), for PF of 75.8 (23.2), for EF of 62.2 (25.8), for FA of 42.2 (29.60) and for PA of 38.1 (31.5). The Median TUDDs for the 5 targeted dimensions was 10.1 months [7.5-16.9] for GHS, 6.1 months [4.1-8.9] for PF, 21.6 [18.7-31.2] for EF, 10.8 [6.2-16.6] for FA and 13.6[10.1-22.5] months for PA. CTC counts were available in 261 patients at base line and in 229 patients after 4 weeks of treatment, before second cycle of chemotherapy. CTC high count was independent of main clinical and biological characteristics except lobular subtype. We confirmed the poor outcome of patients with high CTC count at base line and after one cycle of treatment with the threshold of &amp;gt; 4CTC/7.5 ml of blood. Out of the 5 dimensions of HRQOL, TUDD of EF was significantly correlated with a high CTC level at base line (p=0.0262) and even more with still an elevated count of CTC after one cycle of chemotherapy(p=0.0137). There was no association of CTC with the other dimensions of HRQOL. Conclusion: This is the first study ever reporting an analysis of QoL and CTC. We observed an association of high CTC count with one component of HRQOL scale. This suggests that CTC could be complementary to clinical factors that could influence HRQOL in HER2 negative metastatic BC treated with first line chemotherapy. Citation Format: Jean-Yves Pierga, Oumar Billa, Sandrine Dabakuyo, Jérôme Lemonnier, Frédérique Berger, Olivier Trédan, William Jacot, Anthony Gonçalves, Marc Debled, Christelle Levy, Christelle Jouannaud, Marie-Ange Mouret-Reynier, Jean-Marc Ferrero, Florence Dalenc, Fatima-Zohra Toumi, Franck Bonnetain, Francois-Clement Bidard, Shufang Renault. Circulating tumor cells enumeration and Health Related Quality of Life of patients treated with first-line chemotherapy for HER2 negative metastatic breast cancer [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 P4-07-24.