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Background:ALP is an alpha-selective PI3K-inhibitor approved in combination with fulvestrant for PIK3CA-mt HR+/HER2- advanced breast cancer (aBC). These mutations may either be truncal (clonal) or acquired (subclonal) under treatment pressure; however, data regarding the efficacy of ALP in these two populations are currently limited. This study utilized RWE to assess how the PIK3CA genomic environment impacts ALP response. Methods: RWE was sourced from the GuardantINFORM (Guardant Health) database, which comprises aggregated commercial payer health claims and de-identified records from over 100,000 individuals with comprehensive ctDNA results via Guardant360 (G360). All HR+/HER2- aBC patients with one or more of the 11 PIK3CA-mt cited in the Therascreen PIK3CA RGQ PCR Kit ALP companion diagnostic approval (P190001) identified on a G360 since May 2019 were included. Patients must have had at least one claim of ALP after the index G360 test. Patients who received ALP claim(s) in the six months prior to their G360 test were excluded. PIK3CA-mt were defined by clonal fraction (copy number-adjusted PIK3CA mutation allelic fraction/maximum somatic mutation allelic fraction) >50% (clonal) or ≤50% (subclonal). Real-world time to discontinuation (rwTTD) and real-world time to next treatment (rwTTNT) were assessed as proxies for progression free survival. Log-rank tests were used to assess differences in rwTTD and rwTTNT and Chi-squared tests were used to compare the proportion of PIK3CA-mt and other co-occurring alterations between patients with only clonal and only subclonal PIK3CA-mt. Results:Of 223 eligible patients, 216 (96%) had no prior ALP exposure and were included for further analysis. Most patients had one PIK3CA-mt (199, 73%); 177 (82%) harbored only clonal mutations, 34 (16%) harbored only subclonal mutations, 5 (2%) harbored both. We saw no significant difference in rwTTD or rwTTNT for ALP in patients with clonal vs. subclonal PIK3CA-mt [median months to discontinuation = 5.0 (95% CI 4.0 - 6.9) vs. 7.4 (95% CI 3.7 - 11.1) p=0.82; median months to next treatment =7.0 (95% CI 5.5-9.4) vs. 9.0 (95% CI 4.0-12.6) p=0.81]. We observed no significant differences in the frequency of co-occurring alterations between samples with clonal vs. subclonal PIK3CA-mt (Table 1). Many alterations known to be associated with resistance to ALP and/or CDK4/6 inhibitors were identified, including RB1 and PTEN loss of function mutations. Patients with only subclonal PIK3CA-mt had a significantly higher proportion of E545K and E545G alterations compared to patients with only clonal PIK3CA-mt (E545K: 44% vs 26%, p=0.03; E545G: 6% vs 1%, p=0.017). Conclusions:Examination of RWE in patients treated with ALP after identification of PIK3CA-mt on G360 showed no significant difference in treatment outcomes or co-occurring mutations for clonal vs. subclonal PIK3CA-mt, suggesting that patients with PIK3CA-mt should be considered for ALP therapy irrespective of mutation clonality. While this study focused on outcomes related to PIK3CA hotspot alterations, a significant percentage of patients have PIK3CA non-hotspot alterations; assessment of ALP outcomes in this population is warranted. Table 1.Frequency of co-occurring alterations by PIK3CA-mt clonalityGeneClonal (N=177)Subclonal (N=34)p valueNo.%No.%TP538649%1441%0.428ESR18146%1338%0.419ATM3319%926%0.295EGFR3218%824%0.458RB12514%412%0.714PTEN2212%412%0.914FGFR12112%515%0.644FGFR22011%412%0.938MET1810%26%0.434SMAD4169%13%0.232ARID1A158%515%0.256APC148%39%0.858BRAF148%26%0.683GATA3137%26%0.761KRAS137%39%0.765BRCA1127%39%0.671KIT116%13%0.450CDK12106%13%0.515AR85%39%0.301BRCA285%26%0.732 Citation Format: Dejan Juric, Caroline Weipert, Leslie Bucheit, Rebecca Nagy, Justin Odegaard, Junhua Yu, Nicole Zhang, Jiemin Liao. Impact of PIK3CA mutation (PIK3CA-mt) clonality on alpelisib (ALP) activity based on real-world evidence (RWE) following liquid biopsy testing [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P1-18-07.

Background: Inactivating HRR gene mutations can lead to HRR deficiency (HRD) and predict response to PARPi therapy in patients with breast cancer. Copy number loss and large genomic rearrangements (LGR) can result in HRD but are challenging to detect in ctDNA. Here, we present the analytical validation of homozygous deletions, loss of heterozygosity (LoH) and LGR detection on the Guardant360 (G360) liquid biopsy panel, previously validated for detection of small variants, copy number amplifications, and fusions. We present real-world outcomes of BRCA1/2-mutant PARPi-treated patients to demonstrate the clinical validity of the detected variants. Methods: Analytical validation was performed using the G360 83-gene ctDNA panel. Cell line DNA and clinical patient cfDNA were titrated into matched normal cell line DNA or healthy donor cfDNA to establish the limit of detection (LoD) and precision for copy number loss and LGRs, respectively. Accuracy results were compared to those from an orthogonal, externally validated tissue and ctDNA panel. De-identified, longitudinal, claims data were linked to the cancer genomic profiles in Guardant INFORM, a clinical-genomics database. Advanced PARPi treated breast cancer patients with an inactivating or reversion BRCA1/2 mutation detected by G360 were assessed. Results: The analytical sensitivity (95% LoD) for detecting homozygous and LoH deletions for deletion sizes >10MB was established at tumor fractions (TF) of 12.5% and 25%, respectively. The 95% LoD for LGRs was 0.2% variant allele fraction (VAF). The per-sample false positive rate for copy number loss and LGRs was 1000 advanced breast cancer patients was 1.8%, 16.6% and 0.25% respectively, compared to 2.4%, 56.7% and 0.3% in TCGA. To verify the clinical impact of cfDNA-detected HRR alterations, overall survival was determined for PARPi-treated patients with >1 BRCA1/2 germline or somatic SNV, indel or LGR reversion mutation to be 23.2 months [16.4, 30, CI, n=75] compared to 54.4 [28, NA, CI, n=14] months for BRCA1/2-mutant patients without a reversion (p-value=0.049). Conclusion:. This analytical validation demonstrates that G360 detection of inactivating mutations, including copy number loss and LGRs, is highly sensitive, reliable and robust. Real-world evidence analysis confirmed worse survival outcomes in PARPi treated patients harboring a BRCA1/2 reversion compared to BRCA1/2-mutant patients with no reversion. This data further supports ctDNA as a compelling non-invasive means to identify potential PARPi sensitizing and resistance mutations in patients with advanced breast cancer. Citation Format: Jennifer Yen, Leylah Drusbosky, Caroline Weipert, Nicole Zhang, David Hanna, Catalin Barbacioru, Hao Wang, Alex Artyomenko, Arielle Yablonovitch, Yu Fu, Aaron Hardin, Nagesh Alla, Robert Foley, Max Maligska, Bhargavi Panchangam, Phil Yen, Jane Meisel, Neelima Vidula, Massimo Cristofanilli, Jeremy Force, Michael Dorschner, Martina Lefterova, Elena Helman, Becky Nagy, Darya Chudova, AmirAli Talasaz. Analytical and clinical validation of a ctDNA assay for detecting copy number loss and structural rearrangement variants contributing to homologous recombination and repair (HRR) deficiency [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P5-13-29.

Background: Osimertinib, a 3rd-generation (gen) EGFR tyrosine kinase inhibitor (TKI), is standard of care in front-line (1L) patients with advanced EGFR mutant NSCLC; however, not all subgroups may benefit equally. In the phase 3 FLAURA study, patients with exon 19 deletions (ex19del) had a median progression-free survival (mPFS) of 21.4 months (mo); patients with L858R had a shorter mPFS of 14.4 mo. Poorer outcomes with L858R have also been reported with other 3rd-gen TKIs aumolertinib and lazertinib. These patients are a potential poor-risk subgroup for these therapies. Here, we explored outcomes of patients with L858R-driven NSCLC using real-world datasets (RWDs), analyzed potential contributors to poorer outcomes, including co-mutation incidence and osimertinib potency for each mutation, and report preclinical proof of concept of combination treatment BLU-945, an investigational next-gen L858R inhibitor, with osimertinib. Methods: Two large RWDs were analyzed for survival outcomes in 1L osimertinib-treated patients with ex19del or L858R from MD Anderson Cancer Center (MDACC; n=105) and the clinical-genomic Guardant INFORM database (EGFR ctDNA baseline positive; n=1386). IC50s of osimertinib on EGFR mutations and wildtype were determined in BaF3 cells. Preclinical studies of combination BLU-945 and osimertinib were performed in L858R-driven BaF3 xenograft models. Results: Both RWDs confirmed poorer prognosis for 1L osimertinib-treated patients with L858R vs ex19del. MDACC cohort showed a 12-mo PFS rate of 63% for L858R (n=45) vs 82% for ex19del (n=60); mPFS was immature. Guardant INFORM cohort (ctDNA baseline positive) had a median time-to-treatment discontinuation of 8 mo for L858R (n=517) and 11.4 mo for ex19del (n=869), P=0.003. Poor prognosis factors (including TP53 mutations and co-mutation number) were not significantly different between L858R and ex19del; both had a similar number of off-target mutations in post-osimertinib samples. Strong association was found between osimertinib cellular IC50 and osimertinib clinical trial outcomes (mPFS). Osimertinib exhibited most clinical and cellular activity on ex19del, followed by L858R, then G719X, and then exon 20 insertions. BLU-945 in combination with osimertinib in a BaF3 L858R xenograft model demonstrated a longer duration of response vs osimertinib monotherapy. Conclusions: In both RWDs, 1L osimertinib-treated patients with L858R-driven NSCLC had poorer outcomes vs ex19del, consistent with osimertinib’s weaker activity on L858R. Preclinically, BLU-945 in combination with osimertinib increased L858R inhibition, resulting in more durable antitumor activity in L858R xenografts vs osimertinib alone, supporting rationale for combination treatment in patients with L858R mutations. This combination is being evaluated in 1L patients with L858R in the SYMPHONY study (NCT04862780). Citation Format: Yasir Y. Elamin, Tyler Rouskin-Faust, Nicole Zhang, Teresa Green, Aditya Dhande, Brenton G. Mar, John V. Heymach, Chiara Conti. Poorer outcomes in EGFR L858R-driven NSCLC treated with osimertinib may be addressed with novel combination of BLU-945 and osimertinib [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr LB123.

Background: CDK4/6 inhibitors (CDK4/6i) are standard first-line (1L) regimens for HR+/HER2- advanced breast cancer (aBC). Recent data from the randomized phase II MAINTAIN trial reported a PFS benefit for patients (pts) who received a new endocrine therapy plus ribociclib (ribo) versus new endocrine therapy alone) following progression on CDK4/6i as compared to pts who received endocrine therapy alone. However, second-line (2L) treatment patterns and patient outcomes following 1L CDK4/6i are relatively undescribed. Here we describe real-world 2L treatment patterns following 1L CDK4/6i and associated clinical outcomes from a large clinical genomics database. Methods: Real-world evidence (RWE) was sourced from the GuardantINFORM (Guardant Health) database which comprises aggregated commercial payer health claims and de-identified records from over 207,000 pts with comprehensive circulating tumor DNA (ctDNA) results via Guardant360 (G360) from 2014 to 2021. Pts with HR+/HER2- aBC with >1 claim of CDK4/6i and >1 claim for treatment after the index G360 test were included. Real-world time to treatment discontinuation (rwTTD) and real-world time to next treatment (rwTTNT) were assessed in months as proxies for progression-free survival. Real-world overall survival (rwOS) was also reported in months. Results: 2,795 pts met criteria for inclusion; 2,361 (84.5%) were treated with 1L palbociclib (palbo), 271 (9.7%) with 1L abemaciclib (abema) and 163 (5.8%) with 1L ribo. Chemotherapy (chemo,35.5%) and endocrine-only therapy (32.8%) were the most common 2L therapy regardless of the 1L CDK4/6i agent (Table 1). Other 2L agents included endocrine backbone change (14.7%) or CDK4/6i change (7.7%). Endocrine backbone changes were observed more frequently (15.6%) in pts receiving 1L palbo while CDK4/6i changes were more frequent in pts receiving abema (14.0%) or ribo (22.0%). Pts treated with 2L CDK4/6i had improved rwTTNT, rwTTD and rwOS compared to 2L chemo regardless of 1L agent [rwTTNT: 10.2 (95% CI: 7.2-11.7) vs. 7.2 (6.5-8.1); rwTTD: 6.8 (95% CI: 5.8-8.5) vs. 4.3 (95% CI:3.9-4.7); rwOS: NR (95% CI: 40.0-NR) vs. 34.8 (95% CI: 31.3-37.2)]; improvement in rwTTNT, rwTTD and rwOS were also observed for pts with 2L endocrine backbone changes compared to chemo [rwTTNT: 8.5 (95% CI: 7.2-9.6) vs. 7.2 (6.5-8.1); rwTTD: 6.9 (95% CI: 5.8-7.9) vs. 4.3 (95% CI:3.9-4.7); rwOS: 63.4 (95% CI: 51.2-NR) vs. 34.8 (95% CI: 31.3-37.2)]. Pts treated with 2L alpelisib had the shortest rwOS regardless of 1L CDK4/6i agent used [any 1L: NR (95% CI: 23.6-NR)]. Conclusions: A variety of 2L regimens following 1L CDK4/6i were observed, with an improvement in rwTTNT, rwTTD and rwOS in pts receiving 2L CDK4/6i or 2L endocrine backbone change only relative to 2L chemo. These data are hypothesis generating, and the observed improvement may be secondary to therapy choice versus pts who received 2L chemo having more aggressive disease. Larger randomized trials are ongoing to study sequencing and efficacy of 2L treatments following 1L CDK4/6i. Table 1. Distribution of 2L therapies by 1L CDK4/6i agent. Citation Format: Katherine K. Clifton, Seth A. Wander, Cynthia Ma, Andrew A. Davis, Caroline Weipert, Nicole Zhang, Leslie Bucheit. Real-world second-line treatment patterns and associated clinical outcomes for 2795 patients with advanced HR+ HER2- breast cancer treated with first-line CDK4/6 inhibitors [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 P4-01-18.

204 Background: Treatment of men with metastatic castration-resistant prostate cancer (mCRPC) using drugs targeting the AR pathway is hampered by development of resistance including activating AR ligand-binding domain (LBD) point mutations. AR LBD mutations are found in approximately 10-20% of patients (pts) with mCRPC progressing on AR pathway inhibition (ARPi) therapy and may be associated with AR activation by alternative steroid hormones. We utilized the Guardant INFORM real-world database to explore the detection rate and clinical features associated with AR-LBD mutations in men with mCRPC. Methods: This observational study was conducted in a nationally representative clinical-genomic database of 200,000+ advanced cancer pts undergoing comprehensive ctDNA analysis (Guardant360, Redwood City, CA) between 2014 and 2021, with associated clinical information from administrative claims. ctDNA samples of men with mCRPC were assessed for presence or absence of an activating AR-LBD mutation. The incidence of co-occurring genetic alterations was also investigated. Clinical outcomes were studied for matched cohorts comparing pts following first line (1L) or second line (2L) mCRPC therapy with or without AR-LBD mutations. Results: Of 15,705 prostate cancer pts included in the database, 8420 (53.6%) had mCRPC at the time of sample collection. 4122 (49.0%) of these mCRPC pts had prior treatment with an ARPi, of which 854 (21%) had an AR-LBD mutation. AR-LBD mutation prevalence was 15% in mCRPC pts untreated with an ARPi, 23% in those after 1 line, and 24% in those after 2 lines of ARPi treatment. AR L702H and T878A/S showed the greatest increase in prevalence post abiraterone, whereas AR L702H, T878S and F877L had the greatest increase in prevalence post enzalutamide. Prevalence of AR L702H and H875Y doubled (from 8.8% to 17.5%) for pts that received chemotherapy post ARPi, while AR F877L incidence declined by half (3.5% to 1.7%). Compared to pts without AR-LBD mutations, AR-LBD+ mCRPC pts were enriched for co-alterations in APC, CTNNB1, PTEN, BRCA2, and ARID1A. Rates of TP53 and RB1 alterations were comparable in the AR-LBD+ and ARLBD- cohorts. Matched mCRPC pts had similar time-to-treatment-discontinuation (TTD) and time-to-next-treatment (TTNT) between AR-LBD+ and AR-LBD- mCRPC pts in the 1L and 2L settings; however, AR-LBD+ pts exhibited worse overall survival from 1L mCRPC therapy (50.1 vs 60.7 months, log-rank P=0.013). Conclusions: In this large database, the overall detection rate of activating AR-LBD mutations in men with mCRPC undergoing ctDNA analysis was 21%, and increased with prior use of 2nd generation ARPi (abiraterone and enzalutamide). Men with AR-LBD mutations were more likely to harbor other alterations relevant to tumor progression. These findings inform on the ctDNA prevalence and impact of AR-LBD mutations in a real-world dataset of mCRPC.

246 Background: Data suggests that changes in ctDNA quantity correlate with response to therapy in patients with advanced solid malignancies. However, there is little consistency on how to calculate and interpret such changes. Here, we apply a clinically-validated molecular response algorithm to a RW cohort of patients with aCRC to further evaluate its ability to assess treatment outcomes. Methods: We queried the Guardant INFORM database, which comprises aggregated commercial payer health claims and de-identified records from patients with comprehensive ctDNA testing via Guardant360 (G360) from September 2018-March 2022. Patients with aCRC who received G360 within 15 weeks prior to new treatment initiation (any line of therapy) and a second test 3-15 weeks after treatment initiation were retrospectively evaluated using the G360 Response algorithm. Cox proportional hazards (CPH) were used for RW time to next treatment (TTNT), time to treatment discontinuation (TTD), and overall survival (rwOS) analyses. Patients categorized as molecular responders had a >50% decrease in mean variant allele fraction (VAF) ratio from pre-treatment to on-treatment. Gender, age, line of therapy (LOT) and comorbidities were included as covariates. Median TTNT, TTD, and rwOS were calculated by Kaplan Meier. Results: Of 185 aCRC patients with eligible MR results, 65% received chemotherapy +/- VEGF, 21% received regimens containing anti-EGFR monoclonal antibodies, and 14% received other therapies. 43% of aCRC patients were classified as molecular responders, 42% were non-responders, and 15% were not evaluable by the algorithm due to no/low ctDNA at one or both timepoints. 16% of patients cleared their ctDNA on treatment (i.e., ctDNA became undetectable). Molecular responders had significantly longer TTNT (median 10.1 months vs 6.1 months; HR p < 0.005), TTD (median 5.2 Months vs 3.9 months, HR p=0.041), and rwOS (not reached vs 17.8 months, HR p=0.017). Conclusions: Patients with aCRC classified as molecular responders, as calculated by this algorithm, had prolonged time on treatment and overall survival. Compared to tumor markers, ctDNA has a short half-life, which can allow for early response assessment, as shown by our study. These findings are relevant for clinical care, with future potential to allow for adaptive clinical trial design. [Table: see text]

808 Background: The impact of BRAF V600E, a known poor prognostic factor in metastatic colorectal cancer (CRC), has not been assessed broadly in non-CRC gastrointestinal (GI) cancers including pancreatic (PC), gastric/gastroesophageal (GC), hepatocellular carcinoma (HCC) and cholangiocarcinoma (CCA). In view of recent tumor-agnostic approval of a BRAF V600E inhibitor, it is important to determine the prevalence and impact of BRAF alterations on non-CRC GI cancer patients (pts). Methods: Genomic results from pts with PC, GC, HCC, or CCA tested with Guardant360 (G360, Guardant Health) as part of clinical care from June 2019 – June 2022 were retrospectively queried. Prevalence of characterized nonsynonymous BRAF genomic alterations (GA) was analyzed; differences between cancer types was assessed using the Chi-squared test. The GuardantINFORM database with aggregated commercial payer health claims and de-identified records from over 243,000 individuals with G360 results was used to derive real-world overall survival (rwOS), reported in months, calculated from diagnosis of metastatic cancer; differences between cancer types were compared using log-rank tests. Results: 23,069 patients were included: PC:49%; GC:24%; CCA:20%; HCC:6%. Pts were more likely to be male (p

Objective To provide a conceptual framework to guide investigations into burdens of noncancerous genitourinary conditions (NCGUCs), which are extensive and poorly understood. Methods The National Institute of Diabetes and Digestive and Kidney Diseases convened a workshop of diverse, interdisciplinary researchers and health professionals to identify known and hidden burdens of NCGUCs that must be measured to estimate the comprehensive burden. Following the meeting, a subgroup of attendees (authors of this article) continued to meet to conceptualize burden. Results The Hidden Burden of Noncancerous Genitourinary Conditions Framework includes impacts across multiple levels of well-being and social ecology, including individual (ie, biologic factors, lived experience, behaviors), interpersonal (eg, romantic partners, family members), organizational/institutional (eg, schools, workplaces), community (eg, public restroom infrastructure), societal (eg, health care and insurance systems, national workforce/economic output), and ecosystem (eg, landfill waste) effects. The framework acknowledges that NCGUCs can be a manifestation of underlying biological dysfunction, while also leading to biological impacts (generation and exacerbation of health conditions, treatment side effects). Conclusion NCGUCs confer a large, poorly understood burden to individuals and society. An evidence-base to describe the comprehensive burden is needed. Measurement of NCGUC burdens should incorporate multiple levels of well-being and social ecology, a life course perspective, and potential interactions between NCGUCs and genetics, sex, race, and gender. This approach would elucidate accumulated impacts and potential health inequities in experienced burdens. Uncovering the hidden burden of NCGUCs may draw attention and resources (eg, new research and improved treatments) to this important domain of health.

Background For HR+ MBC, ESR1 point mutations (ESR1-MUT) are a common mechanism of acquired resistance to aromatase inhibition (AI); ESR1 fusions (ESR1-FUS) are rare and promote intrinsic resistance to ER-targeting drugs. Retrospective analyses of CDK4/6i trials suggest ESR1-MUT does not cause CDK4/6i resistance, but whether CDK4/6i is effective for ESR1-MUT, or for ESR1-FUS, in the real-world setting is unknown. Methods Real-world evidence was sourced from the GuardantInform database of commercial payer claims and ctDNA tests from 170,000+ individuals. Patients with MBC who started CDK4/6i within 30 days of ctDNA testing were categorized as ESR1-MUT vs. ESR1-WT and analyzed for time-to-next-treatment (TTNT). Separately, cases with ESR1-FUS detected by tissue RNA-Seq were extracted from a clinicopathologic database at an academic cancer center. Results There was no significant difference in TTNT on CDK4/6i for ESR1-MUT vs. ESR1-WT. As expected, ESR1-MUT had shorter overall survival (OS), even after adjustment for age, CDK4/6i drug, and prior treatment (HR 0.58 (0.42-0.82), p=0.002, multivariable Cox). Endocrine partner analysis was limited by lack of clinical annotation to 27% of cases: AI was given to 55% of ESR1-WT and 25% of ESR1-MUT; fulvestrant was given to 39% of ESR1-WT and 68% of ESR1-MUT. Additional stratified analyses will be presented. In the clinicopathologic database, we identified 4 ESR1-FUS cases, and all received CDK4/6i. Progression-free survival durations on CDK4/6i were 4, 10, 11, and 33+ months. Conclusions Using real-world evidence, we demonstrate that CDK4/6i is effective in both ESR1-MUT and ESR1-WT HR+ MBC, supporting the use of CDK4/6i in this setting. CDK4/6i may be additionally beneficial for patients with ESR1-FUS. Future directions include expanding the ESR1-FUS cohort and deciphering the heterogeneity of CDK4/6i responses in this patient population. ESR1-WT ESR1-MUT p-value n=612 n=145 TTNT, median days (95% CI) 99 (85-121) 102 (85-152) 0.84 (log-rank) OS, median years (95% CI) 5.1 (4.5-NA) 2.2 (2.0-NA) Citation Format: Jamie O. Brett, Caroline M. Weipert, Lauren L. Ritterhouse, Nicole Zhang, Junhua Yu, Lianne Y. Ryan, Laura M. Spring, Miguel N. Rivera, Jochen K. Lennerz, Dora Dias-Santagata, Leif W. Ellisen, Aditya Bardia, Seth A. Wander. CDK4/6 inhibition (CDK4/6i) is effective in the real-world setting for hormone receptor-positive metastatic breast cancer (HR+ MBC) with ESR1 mutations and fusions [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5248.

Background: Oncogenic BRAF alterations can be categorized by their distinct structural and signaling properties which lead to activation of the MAPK pathway: class I - kinase active signaling of BRAF mutant monomers; class II - kinase active signaling of BRAF mutant dimers; and class III - kinase impaired BRAF that signals via RAS-dependent, heterodimers containing wild-type RAF. There are currently no approved BRAF targeted therapies for patients whose tumors bear BRAF class II or III alterations. This research utilizes the GuardantINFORM࣪ clinical-genomic database to assess the real-world occurrence and outcomes of patients with oncogenic BRAF alterations by distinct classes across solid tumors.​ Methods: This observational study utilized a database containing clinical and genomic data from ~160,000 cancer patients with ctDNA profiling by the Guardant360 assay. Patients were categorized using a broad list of known and putative class I, II or III BRAF alterations compiled from published sources. Patients were stratified by BRAF mutant class for real-world overall survival analyses. Results: The analysis identified a cohort of over 5,890 patients with oncogenic BRAF alterations. Class II and III alterations were present in more than 2% of all ctDNA positive patients and made up approximately 55% of all the oncogenic BRAF alterations. Class II and III accounted for 65%, 30% and 20% of oncogenic BRAF alterations in NSCLC, CRC and melanoma respectively. NSCLC and melanoma patients with class II or III BRAF alterations experienced shorter overall survival relative to patients with class I alterations. Conclusions: The analysis of this large real-world dataset identified a substantial number of cancer patients with BRAF class II and III alterations. NSCLC and melanoma patients with BRAF class II and III alterations experienced inferior clinical outcomes and represent a population that could benefit from novel targeted therapies. Overall survival in NSCLC and melanoma patients with BRAF class I, II or III alterations Cohort Median OS Months (%95 CI) Unadjusted P-value Class I Class II Class III I vs II I vs III II vs III NSCLC (n=938) 44.8 (37.5,52.8) 34.4 (27.5,41.5) 32.3 (28.4,40.9) 0.006 0.0126 0.6611 Melanoma (n=333) 46.5 (42.3,65.5) 28.5 (8.6,30.3) 30.5 (12.5,73.8) 0.0008 0.0165 0.6529 Citation Format: Paul L. Severson, Elifnur Yay Donderici, Nicole Zhang, Aleksandra Franovic, Nichol Miller, Eric Martin, Eric Murphy, Richard Williams. Occurrence of BRAF class II and III alterations is common across solid tumors and is associated with inferior clinical outcomes in NSCLC and melanoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 4122.

1011 Background: The approvals of CDK4/6 inhibitors (CDK4/6i) and alpelisib (a PI3Ka inhibitor, PI3Ki) have overhauled early treatment of hormone positive aBC. While some clinical trials have investigated mechanisms of resistance to these drugs, their impact on tumor evolution requires further exploration. Here we use cfDNA to examine molecular changes pre- and post-CDK4/6i or PI3Ki treatment and use RWD to assess the impact of putative resistance alterations on response to treatment. Methods: Patients (pts) with aBC were identified via the Guardant INFORM database and included if they had a cfDNA test within 90 days prior to therapy initiation and/or 90 days after therapy discontinuation with CDK4/6i or PI3Ki. Pts with RB1 loss of function (LOF) alterations (alts) who received CDK4/6i and pts with PTEN LOF alts who received PI3Ki were separately identified, and these cohorts were matched 1:3 with a RB1/PTEN negative population respectively, by age (+/- 5 years), sex, year of cfDNA test, and line of therapy. Log-rank tests were used to assess differences in time to discontinuation (TTD) and time to next treatment (TTNT). Results: Differences in the frequencies of certain alts detected in pts pre- and post-CDK4/6i or PI3Ki treatment are shown (Table). Pts with RB1 LOF alts prior to the start of CDK4/6i had significantly worse TTD and numerically worse TTNT versus controls (TTD = 3 mos vs 4.7 mos, p=0.018; TTNT = 7.3 mos vs 8 mos, p=0.082). Pts with PTEN LOF alts prior to start of PI3Ki had no significant difference in TTD or TTNT versus controls (TTD = 4.1 mos vs 4.1 mos, p=0.92; TTNT = 7.4 mos vs 7 mos, p=0.32). Notably, 54% of pts receiving CDK4/6i and 84% of pts receiving PI3Ki were on their third or later line of therapy. Conclusions: Using cfDNA, we were able to further characterize the resistance landscape of both CDK4/6i and PI3Ki, and identified specific ESR1, RB1 and PTEN alterations that appear likely to occur under the pressure of therapy. Our real-world analysis examining RB1 LOF alts added further evidence to suggest it may be both a primary and acquired resistance mechanism to CDK4/6i. As a non-invasive alternative to tissue biopsies, this data further illustrates that cfDNA can provide unique insight into tumor evolution and disease progression in the aBC setting. [Table: see text]

56 Background: Identification of MSI-H is clinically meaningful in patients with aGI given the associated approval of multiple immune checkpoint inhibitors. MSI-H has long been assessed via tissue analysis; and insights from plasma-based approaches are limited to small validation studies. We sought to assess prevalence of initial and acquired MSI-H status across aGI and report real-world outcomes of colorectal (CRC) patients who received ICI after MSI-H identification by a commercially available liquid biopsy (LBx) assay. Methods: Genomic results from a well-validated LBx assay (Guardant360) completed as part of usual clinical care between 10/1/2018-9/7/2021 in patients with aGI were queried to assess MSI-H prevalence and identify cases of potential acquired MSI-H. Real-world evidence (RWE) was sourced from the GuardantINFORM database comprised of aggregated payer claims and de-identified records from 11/1/2018-3/31/2021. Patients with plasma-identified MSI-H who started new therapy < 60 days after assay report date were sorted into treatment groups: chemotherapy +/- biologic therapy (“chemo”) or immunotherapy via pembrolizumab or nivolumab (“ICI”). Real-world time to discontinuation (rwTTD) and real-world time to next treatment (rwTTNT) were assessed as proxies for progression free survival. Log-rank tests were used to assess differences in rwTTD, rwTTNT and overall survival. Results: Prevalence of MSI-H was ̃2% across aGI (Table). Five cases were observed to have potential acquired MSI not attributable to tumor shed identified on serial LBx tests. Of 222 MSI-H CRC patients eligible for RWE analysis, 89(40%) started new therapy within 60 days of results: 42(48%) received ICI, 39(44%) received chemo, 8(9%) received other/mixed regimens. Patients who received ICI had significantly longer rwTTD and rwTTNT compared to patients who received chemo [median months to discontinuation = 7.5 (95% CI 3.4-12.3) vs. 2 (95% 1.4-3.3) p

Background: Hospital admissions among people dying with dementia are common. It is not known whether identification of palliative care needs could help prevent unnecessary admissions. Aim: To examine the proportion of people with dementia identified as having palliative care needs in their last year of life, and the association between identification of needs and primary, community and hospital services in the last 90 days. Design: Retrospective cohort study using Discover, an administrative and clinical dataset from 365 primary care practices in London with deterministic individual-level data linkage to community and hospital records. Setting/participants: People diagnosed with dementia and registered with a general practitioner in North West London (UK) who died between 2016 and 2019. The primary outcome was multiple non-elective hospital admissions in the last 90 days of life. Secondary outcomes included contacts with primary and community care providers. We examined the association between identification of palliative care needs with outcomes. Results: Among 5804 decedents with dementia, 1953 (33.6%) were identified as having palliative care needs, including 1141 (19.7%) identified before the last 90 days of life. Identification of palliative care needs before the last 90 days was associated with a lower risk of multiple hospital admissions (Relative Risk 0.70, 95% CI 0.58–0.85) and more contacts with the primary care practice, community nurses and palliative care teams in the last 90 days. Conclusions: Further investigation of the mechanisms underlying the association between identification of palliative care needs and reduced hospital admissions could help reduce reliance on acute care for this population.

[Figure: see text] BACKGROUND AND OBJECTIVES: Use of commercial direct-to-consumer (DTC) telemedicine outside of the pediatric medical home is increasing among children, and acute respiratory infections (ARIs) are the most commonly diagnosed condition at DTC telemedicine visits. Our objective was to compare the quality of antibiotic prescribing for ARIs among children across 3 settings: DTC telemedicine, urgent care, and the primary care provider (PCP) office. METHODS: In a retrospective cohort study using 2015–2016 claims data from a large national commercial health plan, we identified ARI visits by children (0–17 years old), excluding visits with comorbidities that could affect antibiotic decisions. Visits were matched on age, sex, chronic medical complexity, state, rurality, health plan type, and ARI diagnosis category. Within the matched sample, we compared the percentage of ARI visits with any antibiotic prescribing and the percentage of ARI visits with guideline-concordant antibiotic management. RESULTS: There were 4604 DTC telemedicine, 38 408 urgent care, and 485 201 PCP visits for ARIs in the matched sample. Antibiotic prescribing was higher for DTC telemedicine visits than for other settings (52% of DTC telemedicine visits versus 42% urgent care and 31% PCP visits; P < .001 for both comparisons). Guideline-concordant antibiotic management was lower at DTC telemedicine visits than at other settings (59% of DTC telemedicine visits versus 67% urgent care and 78% PCP visits; P < .001 for both comparisons). CONCLUSIONS: At DTC telemedicine visits, children with ARIs were more likely to receive antibiotics and less likely to receive guideline-concordant antibiotic management compared to children at PCP visits and urgent care visits.

e21143 Background: The clinical utility of ctDNA analysis for biomarker identification in advanced non-small cell lung cancer (NSCLC) has been established, supporting clinical adoption of this testing modality. All FDA-approved, immune-checkpoint inhibitor (ICI) immunotherapies require the prerequisite of negativity for ALK rearrangement and EGFR mutation, or prior toxicity or progression on oral therapies targeting mutations in these genes. Despite these recommendations and support from the American Society of Clinical Oncology and National Comprehensive Cancer Network, broad-panel marker testing for targeted therapy options in NSCLC continues to be underperformed. Data are even limited on when those tests are typically conducted and the effects of timing on the treatment outcomes. Methods: The GuardantINFORM™ clinic-genomic database was interrogated for patients over the age of 18 having a Guardant360 test positive for EGFR mutations of L858R or exon 19 after 2016 and known to have a confirmed diagnosis of lung cancer one year prior to testing. Patients had to have at least three claims prior to, and 90 days of follow-up after, their test. Patients were stratified into three groups by pre- and post-test treatment: 1) patients treated with an EGFR tyrosine kinase inhibitor (TKI) as a first-line treatment after the test, with no other chemotherapy, ICI immunotherapy (IO), or targeted therapy before the test; 2) patients with other first-line treatments prior to the test and then EGFR TKI immediately following the test; and 3) patients treated with ICI or chemotherapy after the test and before EGFR TKI or patients not treated after the test. Real-world time to next treatment (rwTTN) was defined as the index date to the treatment different than the index therapy. Progression free survival (PFS) time was defined as rwTTN or time to death, whichever came earlier. Patients who experienced adverse events (AEs) associated with chemotherapy or IO were reported as a percentage (p-value first-line treatment) and the other two groups based on the Cox proportional hazard model [hazard ratio=1.8, p-value

9106 Background: The introduction of KRAS G12C inhibitors into clinical trials has demonstrated promise and may provide a new therapeutic option for patients (pts) harboring KRAS G12C mutations. Recent data has also indicated that immune checkpoint inhibitors (ICI) have shown benefit in KRAS G12C mutant lung adenocarcinoma (LUAD); however, data on the impact of co-occurring STK11 mutations on outcomes are conflicting. We utilized the Guardant INFORM real-world clinical-genomic database to assess the impact of co-occurring STK11 mutations on outcomes in pts with KRAS G12C mutant LUAD treated with a first-line ICI containing regimen. Methods: This retrospective matched cohort observational study was conducted in a nationally representative clinical-genomic database covering over 137,000 pts with comprehensive ctDNA results and associated clinical information. Adult pts with metastatic LUAD who received ≥ 1 dose of first-line anti-PD1/PD-L1 ± chemotherapy and had at least 90 days follow-up after first KRAS G12C detection were included. A cohort of pts without KRAS G12C, including KRAS wildtype pts and pts with other KRAS mutations, were matched 3:1 for age, gender, year of index and baseline comorbidity. Time to next treatment (TTNT), time to discontinuation (TTD), real-world overall survival (rwOS) were compared with vs. without STK11 mutations for both cohorts using cox proportional-hazards model. Results: Among 330 pts in the KRAS G12C cohort, 21% (n = 70) had an STK11 mutation. Among the matched cohort (n = 938), 754 pts were KRAS wildtype, of whom 6% (n = 49) had STK11 mutations. Within the KRAS G12C cohort, pts with STK11 mutations had statistically significant shorter TTNT (hazard ratio [HR] 2.7, 95% confidence internal [CI] 1.8-4.0, p < 0.0001), TTD (HR 1.4, 95% CI 1.0-2.0, p < 0.04) and rwOS (HR 3.2, 95% CI 2.0-5.1, p < 0.0001) than pts without STK11 mutations. Within the matched KRAS wildtype cohort, the differences in TTD (HR 1.4, 95% CI = 1.0-2.0, p = 0.08) and rwOS (HR 1.4, 95% CI = 0.8-2.4, p = 0.3) in patients with vs. without STK11 mutation did not reach statistical significance (Table). Conclusions: This study provides real-world evidence that STK11 co-mutations are associated with worse outcomes among pts with KRAS G12C mutant LUAD treated with first-line ICI. These inferior outcomes indicate a high unmet medical need among LUAD pts harboring co-occurring KRAS G12C and STK11 mutations and demonstrate the need for effective targeted and/or combination therapies in this patient population.[Table: see text]

Background: To overcome the challenges of delivering patient care in the twenty-first century, it is essential to foster the professional and personal qualities of courage and resilience in the nursing workforce. The logical place to do so is in nursing education and training.Objectives/Hypotheses: This paper discusses the constructs of courage and resilience in nursing and the application of the constructs in nursing education.Design: This is a discussion article drawing on the relevant literature and the professional experiences of the authors to develop a conceptual model for teaching courage and resilience.Results: To promote nursing students' coping strategies and their general well-being, nurse educators should foster resilience and courage through various educational interventions.Conclusion: The proposed conceptual model shows that nurse educators should train nurses to be more resilient and courageous in order to promote patient safety, handle the demands of the profession, and function as advocates for the discipline.

Commentary on : Balk EM, Rofeberg VN, Adam, GP, et al . Pharmacologic and nonpharmacologic treatments for urinary incontinence in women: a systematic review and network meta-analysis of clinical outcomes. Ann Intern Med 2019 Mar 19. doi: 10.7326/M18-3227. UI is a prevalent condition across the globe. UI is pervasive in all care settings and communities.1 There has been significant research regarding non-pharmacological and pharmacological interventions alike that are efficacious in treating UI.2 3 While this is the case, there have …

39 Background: Clinical insights gained from real-world data have led to numerous advances in oncology including new and expanded drug approvals and an understanding of real-world clinical utilization. In this precision oncology age, integrating real-world clinical data with genomic data can lead to further advancements. We aimed to understand the genomic and treatment landscape in advanced colorectal cancer (aCRC) by leveraging a uniquely large and detailed clinical-genomic database. Methods: The GuardantINFORM (Guardant Health) database comprises aggregated commercial payer health claims and de-identified records from over 100,000 individuals with comprehensive ctDNA results (Guardant360). GuardantINFORM was queried for patients (pts) with a diagnosis of CRC. Pts with fewer than two pharmacy claims prior to or after the first ctDNA test were excluded from the regimen analysis. Latest claims data was truncated as of 8/31/2020. Results: 10,845 pts had a total of 13,510 ctDNA tests (1 – 19 tests/pt). The first ctDNA test date was from 06/2014 - 06/2020. The majority of pts had one ctDNA test (86.7%) while 5% had three or more tests. 87.9% of ctDNA tests had at least one genomic alteration identified, with the distribution of alterations consistent with prior reports (Table). 78% of pts had at least two pharmacy claims before and/or after the first ctDNA test. Of those pts with at least one CRC treatment, the most commonly prescribed CRC regimens up to one year prior to the first ctDNA test were FOLFOX +/- bevacizumab (16%, 18%), FOLFIRI +/- bevacizumab (17%, 11%), capecitabine (15%), 5-FU (12%), and regorafenib (5.2%). Anti-EGFR mono and combination therapy was reported in 6% and 16% of pts pre ctDNA testing. Immune checkpoint inhibitor (ICPi) mono and combination therapy was reported in 2% and 0.5% of pts. The most commonly prescribed CRC regimens post first ctDNA test were capecitabine (16%), FOLIRI +/- bevacizumab (15%, 13%), tipiracil and trifluridine (15%), FOLFOX +/- bevacizumab (12%, 14%), 5-FU (11%), and regorafenib (10%). Anti-EGFR mono and combination therapy was reported in 8% and 18% of pts post ctDNA testing. ICPi mono and combination therapy was reported in 5% and 1% of pts. Conclusions: Using a large and uniquely detailed clinical-genomic dataset, we produced results that replicate the observed distribution of ctDNA identified mutations present in aCRC. This genomic information combined with real-world clinical data provides valuable insights into the variety of longitudinal treatments, including before and after comprehensive ctDNA genomic profiling, allowing for detailed outcomes research, especially focused on precision oncology. [Table: see text]

Background Previous research reported that individuals prescribed antibiotics frequently develop antimicrobial resistance. The objective of this study was to evaluate whether frequent antibiotic use is associated with reduced hospital admissions for infection-related complications. Methods Population-based cohort study analysing electronic health records from primary care linked to hospital admission records. The study population included patients prescribed a systemic antibiotic, recent record of selected infections and no history of chronic obstructive pulmonary disease. Propensity-matched cohorts were identified based on quintiles of prior antibiotic use in 3 years before. Results A total of 1.8 million patients were included. Repeated antibiotic use was frequent. The highest rates of hospital admissions for infection-related complications were observed shortly after antibiotic start in all prior exposure quintiles. For patients with limited prior antibiotic use, rates then dropped quickly and substantially. In contrast, reductions over time were substantially less in patients with frequent prior antibiotic use, with rates remaining elevated over the following 6 months. In patients without comorbidity comparing the highest to lowest prior exposure quintiles in the Clinical Practice Research Databank, the IRRs were 1.18 [95% CI 0.90–1.55] in the first 3 days after prescription, 1.44 [95% CI 1.14–1.81] in the days 4–30 after and 3.22 [95% CI 2.29–4.53] in the 3–6 months after. Conclusions Repeated courses of antibiotics, although common practice, may have limited benefit and indicator of adverse outcomes. A potential mechanism is that antibiotics may cause dysbiosis (perturbations of intestinal microbiota), contributing to colonization with resistant bacteria. Antibiotics should be used judiciously and only periodically unless indicated. Antimicrobial stewardship should include activities focusing on the substantive number of patients who repeatedly but intermittently get antibiotics.

Introduction: Influenza is a preventable infectious disease and remains a serious problem for many countries due to its worldwide spread. Despite the often, short duration of illness, it poses a substantial healthcare burden. There is dearth of country-specific data on the burden of flu. Objective: To estimate the burden of influenza and the impact of vaccination in Europe over the next decade. Methods: Our analysis is based on critically- appraised literature evidence that reports seropositive symptomatic events of Influenza. In absence of country-specific reliable data, we derived our estimates from a U.S. based study to 28 EU countries (Sullivan K, 1996). To make valid extrapolations from the U.S. study to European countries, we developed a model using ratios of lower respiratory tract infections risk, reported by the IHME Global Burden of Disease Study. The event rates are adjusted per the risk reduction factor and recent recommendations for seasonal flu vaccine and its coverage. Results: We estimate 17.8 million events of influenza in Europe in 2018. Among the countries we report, event rate is highest in Lithuania and lowest in Luxembourg at 98.9 and 17.4 per 1000. Children under 15 years account for nearly 50% of all events. Due to increasing vaccine uptake, we estimate 2 million fewer flu events by 2028, across the major European countries. Conclusion: Combined with 10-year forecast, our results facilitate identification of countries at risk and opportunities for averting flu in the vulnerable countries. Both increased vaccination coverage and development of vaccines are complementary approaches and will better protect European population from seasonal flu.

Commentary on: Nelis SM, Wu YT, Matthews FE, et al . The impact of co-morbidity on the quality of life of people with dementia: findings from the IDEAL study. Age Ageing 2019;48:361–7. doi: 10.1093/ageing/afy155. Dementia is an increasingly common health problem.1 Many individuals live with comorbidities and this is also true of those individuals with dementia. A recent editorial summarised the landscape of dementia and comorbidities through the following points: (1) comorbidities negatively influence QoL; (2) dementia …

Objective: We aimed to estimate the global prevalence of type 2 diabetes over the next ten years, taking into account trends in obesity. Our analysis includes estimates for 45 countries representing almost 90% of the world population. We defined a prevalent case as anyone living with type 2 diabetes, irrespective of whether it has been formally diagnosed or not and excluded type 1 diabetes cases. Methods: We performed a global systematic search of published studies and other data sources that reported the prevalence of type 2 diabetes, as well as any factors that may change its risk or prognosis over time or between countries. Our analysis is based on critically-appraised literature and database evidence that reports the total prevalence of type 2 diabetes. From the results of this search, we appraised and selected country-specific estimates to project up to national totals. These estimates were adjusted to account for historical or future trends in risk, as well as relevant differences between countries when extrapolations were made. Our model includes country-specific obesity prevalence to incorporate the impact of obesity on diabetes trends. Results: We estimate that in 2018 there are more than 500 million prevalent cases of type 2 diabetes worldwide and the prevalence is comparable between high- and low-income countries. The prevalence will increase in all countries covered over the projection period, but the greatest growth will be experienced in lower-income countries. Disclosure A. Bradshaw Kaiser: None. N. Zhang: None.

Commentary on : Pouwels KB, Hopkins S, Llewelyn MJ, et al . Duration of antibiotic treatment for common infections in English primary care: cross sectional analysis and comparison with guidelines. BMJ 2019;364:l440. doi: 10.1136/bmj.l440 The realisation that antibiotic overuse can be harmful has shaped modern global movements of antibiotic prophylaxis and stewardship. Furthermore, nursing has had an established role in this movement.1 As a result, adherence to guidelines for antibiotic treatment for numerous common infections is a …

Introduction: CD123 is a component of the IL-3 receptor expressed in several hematological malignancies including AML, ALL, HCL, and MDS. CD123 is a compelling target in AML due to its overexpression on AML blasts as well as leukemic stem cells, which are thought to be resistant to chemotherapy and may be responsible for relapse of disease following treatment. While CD123 is expressed by some normal leukocyte populations in circulation and hematopoietic progenitor cells in the bone marrow, the low frequency of expression on normal cell types provides a therapeutic window for targeting CD123 in tumor settings with the potential for durable response and reversible side effects. We have developed bispecific anti-CD123 x anti-CD3 ADAPTIR molecules APVO436 and APVO437 for redirecting T-cell cytotoxicity to CD123-expressing tumor cells. Results are presented that examine the in vitro and in vivo activity of these molecules in preclinical models of AML. Methods: APVO436 and APVO437 proteins were expressed in CHO cells. Affinity SPR studies were performed using recombinant CD123-ectodomain. In vitro functional studies were conducted with CD123+ AML tumor cell lines and primary human and cynomolgus macaque T-cell populations. Cytotoxic activity was determined using chromium release assays. On-cell binding, T-cell activation and proliferation were assessed using multi-color flow cytometry. Pharmacokinetic parameters were determined in BALB/c mice using a single IV dose of approximately 10 mg/kg. In vivo studies to examine tumor growth inhibition activity were performed with NOD/SCID mice co-implanted subcutaneously with AML tumor cells and human T-cells followed by treatment with APVO436 or APVO437. Tumor growth was assessed by measuring tumor volume and Bioluminescent Imaging. Results: APVO436 and APVO437 bound human CD123 protein with high affinity and binding to CD123 and CD3 expressing cell lines was confirmed by flow cytometry. Both APVO436 and APVO437 induced concentration-dependent lysis of CD123+ AML cell lines with primary human effector T-cells, accompanied by T-cell activation and proliferation. Comparable redirected T-cell cytotoxicity function was observed using primary cynomolgus macaque T cells. These activities were dependent on the expression of CD123 by the tumor target cells. APVO436 and APVO437 demonstrated an extended elimination half-life in mouse serum, typical of molecules capable of binding the neo-natal Fc receptor. In vivo, growth of AML tumor cells was inhibited by treatment with low doses of APVO436 and APVO437, significantly improving host survival. Conclusion: Taken together these data demonstrate potent in vitro and in vivo activity of APVO436 and APVO437 against CD123 expressing tumor cells and are supportive of further investigation of this approach as a potential treatment option for AML and other hematological malignancies. Citation Format: Michael R. Comeau, Danielle Mitchell, Rebecca Gottschalk, Lynda Misher, Mollie Daugherty, Lara Parr, Peter Pavlik, Brian Woodruff, Hang Fang, Megan Aguilar, Jeannette Bannink, Starrla Johnson, Gary Li, Robert E. Miller, Robert Bader, Nicole Zhang, Toddy Sewell, Maria Dasovich, Gabriela H. Hoyos, John W. Blankenship, Catherine McMahan, David Bienvenue, Jane A. Gross. Bispecific anti-CD123 x anti-CD3 ADAPTIR™ molecules for redirected T-cell cytotoxicity in hematological malignancies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 597. doi:10.1158/1538-7445.AM2017-597

Background: Effective treatment of metastatic, triple-negative breast cancer (TNBC) remains a highly unmet medical need. We have developed ES425, a bispecific ADAPTIR™ (modular protein technology) molecule that redirects T-cell cytotoxicity to tumor cells expressing ROR1 (receptor tyrosine kinase-like orphan receptor 1), an oncofetal antigen expressed on TNBC and other malignancies. Results are presented for studies run to examine in vitro and in vivo activity of ES425 in preclinical models of TNBC. Materials and Methods: Target-dependent cytotoxic activity was examined in vitro by treating ROR1(+) cell lines and ROR1(−) cell lines with ES425 in the presence of purified human T cells or human peripheral blood mononuclear cells (PBMCs). Cytotoxic activity was determined using chromium release assays. T cells were assessed for activation and proliferation using multi-color flow cytometry. Pharmacokinetics of ES425 in NOD/SCID gamma (NSG) mice was determined using single intravenous dose of approximately 10 mg/kg. Serum concentrations at time points ranging from 15 minutes to 504 hours were used to calculate the terminal elimination half-life of ES425. To assess activity in vivo, NOD/SCID mice were implanted subcutaneously with the ROR1(+) TNBC tumor cell line MDA-MB-231 and purified human T cells and treated with ES425. This model was run twice with T cells from different human donors. Tumor growth was assessed by measuring tumor volume. Results: ES425 efficiently redirected T cell cytotoxicity against ROR1(+) cell lines at low picomolar concentrations in vitro. Cytotoxic activity was dependent on expression of ROR1 by the target cells. T cells were activated and proliferated in response to ES425 in the presence of ROR1(+) target cells; proliferation was not observed in response to ROR1(−) cells. In vivo, pharmacokinetic analysis showed a serum half-life of approximately 7 days in NSG mice, and ES425 inhibited growth of MDA-MB-231 tumors in mouse xenografts. Repeat experiments showed similar inhibition of tumor growth and an improvement in overall survival. Conclusions: These studies show that ES425 may be an efficient agent for redirecting T cell cytotoxicity in preclinical TNBC models and merits investigation as a potential therapeutic in TNBC and other malignancies. Citation Format: John W. Blankenship, Lynda Misher, Danielle Mitchell, Nicole Zhang, Philip Tan, Gabriela H. Hoyos, Padma Ravikumar, Robert Bader, Catherine J. McMahan, Robert E. Miller, Jeannette Bannink, Hang Fang, Lara Parr, Maria Dasovich, David Bienvenue, Megan Aguilar, Carina Xu, Mollie Daugherty, Brian Woodruff, Jane A. Gross. anti-ROR1 x anti-CD3 ADAPTIR™ molecule, ES425, redirects T-cell cytotoxicity and inhibits tumor growth in preclinical models of triple-negative breast cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4995.

Background Partial bladder outlet obstruction due to neurogenic bladder or mechanical obstruction is common amongst the population and can cause bladder injury and dysfunction. Bladder Smooth Muscle Cells (BSMCs) undergo phenotypic changes such as hyper-proliferation, de-differentiation and altered expression of integrins and ECM proteins.[1] Extracellular matrix changes are often crucial inciting events for fibroproliferative disease.[2] Epigenetic change, specifically DNA methylation, may be important factors underlying the persistent fibroproliferative phenotype. Previously, damaged matrix (heat-denatured collagen, DNC) induced hyper-proliferation of bladder smooth muscle cells (BSMC) and the phenotype was not reverted upon a return to normal matrix. [3] We examined the dependency of matrix-induced fibroproliferation and SMC phenotype on DNA methyltransferase activity. The cooperativity of matrix with other inciting stimuli (growth factors, hypoxia and strain) associated with bladder obstruction was also examined.