Multi-parametric liquid biopsy analysis of circulating tumor cells (CTCs), cell-free DNA (cfDNA), and cell-free RNA (cfRNA) in metastatic castrate resistant prostate cancer (mCRPC).

274 Background: Molecular profiling of prostate cancer using liquid biopsies such as CTC capture and cell-free nucleic acid analysis yield informative yet distinct datasets. Additional insights may be gained by simultaneously interrogating multiple liquid biopsy components to construct a more comprehensive molecular disease profile. We have conducted an initial proof of principle study aimed at piloting this multi-parametric approach. Methods: Blood was drawn under an IRB-approved protocol from 20 mCRPC patients. Samples were analyzed simultaneously for the following: CTC enumeration and single CTC and matched white blood cell capture for whole genome amplification and low-pass copy number variation; CTC DNA and matched cfDNA for somatic single nucleotide variant analysis; plasma cfRNA extraction and qRT-PCR for AR, AR-V7, and PCA3. When available, liquid biopsies were compared with matched tumor profiles. Results: Fifteen of 20 patients (75%) had detectable CTCs by CellSearch (range: 1-692/7.5mL, median: 16.5/7.5mL). Thirteen of 20 patients (65%) had detectable SSNVs in CTC DNA and/or matched cfDNA, including mutations in TP53, PIK3CA, HRAS, and EGFR. Matched CTC DNA and cfDNA demonstrated both shared and distinct SSNVs. Copy number analysis of single CTCs was performed in 2 patients, and both had CNVs in multiple cancer relevant genes. A majority of CNVs were present in matched solid tumor profiles, but some were exclusive to the liquid biopsies. Plasma PCA3 and AR transcripts were detected in 18/20 (90%) and AR-V7 in 4/20 (20%) cfRNA samples. Unique SSNVs were detected at second time points at disease progression (more are being collected). Conclusions: In this pilot cohort, simultaneous multi-parametric profiling was feasible for CTC DNA mutations and CNVs, and matched plasma cfDNA mutations and cfRNA gene expression. These disease-specific molecular profiles were often concordant with tumor tissues but also contained new, potentially actionable alterations unique to CTC DNA or cfDNA. Expanded studies will build upon this approach to optimally leverage liquid biopsies for molecularly directed patient management. </jats:p

Safety and efficacy of the erdafitinib (erda) intravesical delivery system, TAR-210, in patients (pts) with non–muscle-invasive bladder cancer (NMIBC) or muscle-invasive bladder cancer (MIBC) harboring select <i>FGFR</i> mutations or fusions: Phase 1 first-in-human study.

TPS583 Background: Treatment options are limited for pts with NMIBC and MIBC who experience disease recurrence or who are ineligible for or refuse standard of care. Erda, an oral selective pan-FGFR tyrosine kinase inhibitor, is approved in adults with locally advanced or metastatic urothelial cancer with select FGFR3/2 alterations ( alt) who have progressed during or after ≥1 line of platinum-containing chemotherapy. FGFRalt are among the most common oncogenic drivers detected in NMIBC and MIBC, and are more prevalent in NMIBC. TAR-210 is an intravesical drug delivery system designed to provide local, continuous release of erda within the bladder, thus limiting systemic toxicity. This study evaluates the safety, pharmacokinetics (PK), and efficacy of TAR-210 in pts with NMIBC or MIBC with select FGFRalt. Methods: Open-label, multicenter phase 1 study of TAR-210 in pts with recurrent NMIBC or MIBC (NCT05316155). Eligible pts are aged ≥18 yrs with adequate organ function and tumors with select FGFRalt. A flexible molecular eligibility strategy is used to allow for local or central fresh/archival tissue-based FGFR testing by next-generation sequencing (NGS) or PCR, or urine cell-free DNA NGS testing. Four cohorts will be enrolled: pts with recurrent, bacillus Calmette-Guerin (BCG)-experienced papillary-only high-risk (HR) NMIBC (high-grade Ta/T1) refusing or ineligible for radical cystectomy (RC) (Cohort 1) or scheduled for RC (Cohort 2); pts with recurrent, intermediate-risk NMIBC (Ta/T1) with a history of low-grade disease (Cohort 3); pts with cT2-T3a MIBC scheduled for RC refusing or ineligible for neoadjuvant cisplatin (Cohort 4). Pts in Cohorts 1 and 2 will have TURBT with resection of all visible disease prior to dosing, whereas pts in Cohort 3 must have visible disease prior to dosing. The primary end point is safety (adverse events, including dose-limiting toxicity). Secondary end points include PK, recurrence-free survival (Cohorts 1 and 2), complete response (CR) rate and duration of CR (Cohort 3), and pathologic CR rate, pT0 rate, and rate of downstaging to &lt;pT2 (Cohort 4). Dose escalation (Part 1; n≈12, Cohorts 1 and 3 only) will be followed by dose expansion (Part 2; n≈50-80). Cohorts 1 and 3: response assessment will be after a 3-mo dosing cycle; pts with CR may receive ≤3 additional 3-mo dosing cycles if no recurrence, progression, or unacceptable toxicity. Cohorts 2 and 4: response assessment will be at RC after 8 wks of dosing. Follow-up disease surveillance (cystoscopy, urine cytology, imaging) will be every 3 mos to end of Yr 2 and every 6 mos in Yr 3 in Cohorts 1 and 3 and at 3 mos post-RC in Cohorts 2 and 4. Four pts were enrolled since April 2022 (1 in Cohort 1, 3 in Cohort 3); enrollment for Cohorts 2 and 4 is planned soon. Clinical trial information: NCT05316155 . </jats:p