Rodriguez, Angel

Abstract Introduction: Among Non-Hodgkin lymphomas (NHL), DLBCL is the most prevalent subtype (~30% of diagnoses). First-line (1L) chemoimmunotherapy cures many patients (pts), but 30-40% will relapse. Prognostic and predictive biomarkers are needed to identify pts refractory to 1L therapy or at high risk of relapse, enabling timely intervention and improved outcomes. This study evaluated tumor-informed WGS-based longitudinal ctDNA monitoring in a real-world DLBCL cohort. Methods: We retrospectively analyzed ctDNA data from 49 pts with DLBCL. Plasma samples were collected before, during, and at the end of 1L therapy (EOT, defined as ± 21 days from the last infusion (preferred when available) or ± 14 days from post-treatment PET imaging) and during surveillance/subsequent treatments. A WGS-based tumor-informed assay (Signatera™ Genome, Natera, Inc.) was used for ctDNA detection and quantification. The association of ctDNA dynamics with event-free survival (EFS) was evaluated using Cox regression analysis, restricted to pts completing at least 5 cycles of 1L therapy. Results: The median age of the cohort was 62 years (range: 56-74), and median follow-up was 22 months (range: 14-30). Pre-treatment ctDNA-positivity rate was 100% (31/31). A total of 19 pts achieved ctDNA clearance during 1L therapy (early clearance within 3 cycles, n=5; late clearance between cycle 4 and EOT, n=14). Pts with no clearance or ctDNA-positivity at EOT (n=7) had significantly inferior EFS compared to those achieving ctDNA clearance (HR 8.04, 95%CI: 1.87-34.62, p=0051). On further stratifying the clearance group and comparing with no clearances, pts with early clearance had superior outcomes (HR 13.22, 95%CI: 1.48-1741.94, p=0.0166), relative to late clearances (HR 5.65, 95%CI 1.46–25.16, p=0.0129). Notably, all 5 pts with early ctDNA clearance remained serially negative and relapse-free. Of the 49 pts, 9 proceeded to chimeric antigen receptor T-cell therapy (CAR-T). Among 6 of these pts with available ctDNA results pre and post therapy, all 3 who stayed ctDNA-positive after CAR-T relapsed (1.3, 2, and 4.5 months post-infusion); 1 pt with pre- and post-CAR-T ctDNA-negativity and 2 pts with ctDNA clearance post-CAR-T remained relapse-free for 9.6, 15.9, and 22.4 months, respectively. Taken together, the PPV and NPV for a single ctDNA time point post CAR-T infusion were 100% for predicting long-term clinical outcomes. Conclusions: Our data support longitudinal ctDNA monitoring as a valuable prognostic and predictive biomarker in DLBCL. ctDNA clearance, particularly early clearance within the first 3 cycles of 1L therapy, is associated with improved pt outcomes. Longitudinal ctDNA monitoring and dynamics can enable identification of high-risk pts who do not clear ctDNA and may benefit from earlier referral for CAR-T. Furthermore, ctDNA monitoring pre- and post-CAR-T infusion is predictive of treatment response and can identify pts at high risk of relapse.

e13042 Background: The conventional treatment paradigm for metastatic breast cancer (MBC) is to continue systemic therapy until disease progression. With improved systemic therapy options, some patients (pts) with MBC attain radiographic remission. Tumor-informed circulating tumor (ct)DNA detects molecular disease burden and may guide decision-making. We report on an institutional cohort of pts with MBC in which tumor-informed ctDNA testing was utilized prospectively to guide decisions on systemic therapy or surveillance imaging frequency. Methods: Utilizing an IRB-approved protocol, we retrospectively identified pts monitored with tumor-informed ctDNA using the Signatera™ mPCR-NGS assay (Natera, Inc) as part of routine clinical care in Mayo Clinic, Rochester. We then identified a subset with biopsy-proven MBC who attained radiographic remission of disease following systemic therapy, deemed by the treating medical oncologist as “exceptional responders”. Real-time ctDNA testing was used to inform a decision to either discontinue systemic therapy, treatment de-escalation (remove a component of multi-drug therapy), increase the time interval between restaging scans, or stay off therapy previously stopped due to toxicity . Data on breast cancer characteristics, imaging results, ctDNA test results, and outcomes were collected. Descriptive statistics were used to analyze the data. Results: 10 pts met our study criteria. The median age at MBC diagnosis was 42 years (range 28-61); 5 pts had TNBC, 3 pts had HER2+, and 2 pts with ER+/HER2- MBC. Most pts (60%) were on first or second line therapy (range 1-5). The median duration of the most recent regimen was 27.5 months (range 10-70 months). All pts were without radiographic evidence of active cancer at the time of ctDNA testing with negative results (0 MTM/mL) at the time of clinical decision-making. 4 pts stopped all systemic therapy and proceeded with observation (1 trastuzumab, 1 trastuzumab deruxtecan, 1 pembrolizumab, and 1 talazoparib). 2 pts discontinued a targeted therapy (1 olaparib, 1 abemaciclib) while continuing endocrine therapy. 1 patient stopped targeted therapy (abemaciclib) due to a blood clot, and ctDNA testing guided the decision to not start another CDK4/6 inhibitor while continuing endocrine therapy. In 3 pts the frequency of restaging scans was decreased to either annually or semi-annually. The median follow-up after a ctDNA-informed decision was 11 months (range 1-41 months). At this time, no patient has converted to ctDNA-positivity, experienced resurgence or progression of disease, needed to change systemic therapy or increase imaging frequency. Conclusions: Tumor-informed ctDNA may offer additional confidence to oncologists and pts to deescalate systemic therapy or decrease the interval of imaging frequency in exceptional responders with MBC. Additional data to support this approach is needed.

Introduction: Nearly 50-60% of the patients withDiffuse large B-cell lymphoma (DLBCL) can be cured by front line chemoimmunotherapy. Current risk stratification modalities include cell-of-origin (germinal center (GCB) or non-GCB (activated B-cell [ABC])) subtyping, use of the revised International Prognostic Index (R-IPI), Ki-67 proliferation index assessment, and cytogenetic aberration detection. However, a novel approach for molecular residual disease (MRD) detection and treatment monitoring is needed to improve patient outcomes. Methods: A personalized and tumor-informed multiplex PCR assay (Signatera™ bespoke mPCR NGS assay) was used for the detection and quantification of ctDNA in a prospective clinical cohort of patients with DLBCL. Serial ctDNA testing was performed at various time points collected at the treating physician's discretion, including pretreatment (baseline), during first-line therapy, during and post-salvage therapy, at the end of treatment, and during surveillance, up to the last clinical follow-up. ctDNA clearance was defined as change in ctDNA status (positive to negative) from the pre-treatment time point to the subsequent time point. Event-free survival (EFS) was defined as the time elapsed since the initial ctDNA clearance or PET imaging, for those without ctDNA clearance, during which the patient did not experience progression, death or treatment with salvage therapy. EFS was censored at the last date of followup if the patient was alive and without an event. Overall survival (OS) was defined as the elapsed time after primary treatment until death from any cause. Univariate and multivariable models were analyzed using Cox proportional models. Results: In this retrospective evaluation of commercial ctDNA testing in patients with stage I-IV DLBCL, a total of 50 patients (I:3, II:12, III: 4, and IV: 29;median age: 59 years) were analyzed. Patients were followed up for a median of 12.68 months (inter quartile range: 7.9-17.7 months). Of the 50 patients, 41 had pre-treatment (baseline) time points available and ctDNA was detected in 95% (39/41) of patients. Since the majority of the patients had stage IV disease, median ctDNA detection levels were observed to be high (overall median: 534 MTM/ml, range: 0-5957 MTM/ml; I median: 9.6 MTM/mL [range: 0.2-2822 MTM/mL], II median: 53 MTM/mL [range: 0.8-862 MTM/mL], III median: 368 [range: 2-940 MTM/mL], IV median: 1011 MTM/mL [range: 74-5958 MTM/mL]). Clearance of ctDNA at any point during first-line therapy was associated with improved outcomes (EFS, HR: 8.3, 95% CI: 2.56-27.0, p<0.0001 and OS, HR: 15.2, 95% CI: 1.53-149, p=0.0021), compared to patients who remained ctDNA-positive. Furthermore, 48% (13/27) of patients were found to clear their ctDNA upon the completion of the first cycle of treatment. On comparing baseline ctDNA levels with other clinicopathological risk factors, high ctDNA levels were observed to be strongly correlated with higher R-IPI scores (0-2 vs. 3-5; p=0.0008) and higher stage (I-II vs. III-IV; p=0.0007). Additionally, multivariate analysis determined that ctDNA clearance significantly outperformed all other clinicopathologic risk factors associated with EFS (HR: 48.8, 95% CI:1.2-2005, p=0.04). Finally, ctDNA clearance predicted complete response (CR)/no evidence of disease (NED) on average 95 days (range: 0-14.7 months) ahead of PET imaging or biopsy. Conclusions: In this study utilizing a real-world cohort of patients with stage I-IV DLBCL, ctDNA clearance during first-line therapy was prognostic for EFS and OS and preceded clinical response. ctDNA testing in patients with DLBCL may enable personalized surveillance, intervention, and/or trial options, ultimately improving patient outcomes.

Abstract Background: In the I-SPY 2 TRIAL, the addition of P to standard NAC resulted in more than doubling of the pathologic complete response (pCR) rates for both hormone receptor-positive (HR+)/HER2- and triple-negative (TN) early breast cancer (EBC) patients (pts) compared to NAC only (Nanda et al, JAMA Oncol, 2020). At 3 years, distant recurrence-free survival (DRFS) rates in pts with pCR following NAC+P was >95%. We hypothesized that ctDNA can serve as a predictive biomarker of response and survival in pts treated with NAC. Methods: A personalized ctDNA test (Signatera) was performed on 511 serial plasma samples from 138 pts with high-risk HR+/HER2- (n=77) or TN (n=61) stage II/III EBC. Pts received P with paclitaxel (Tx) followed by AC (P arm, n=42) or standard NAC only (n=96), an exploratory subset of pts evaluated for P efficacy. Plasma was collected; pretreatment (T0), 3 weeks after treatment initiation (T1), between Tx+/-P and AC regimens (T2), and prior to surgery (T3). ctDNA was deemed positive with a minimum of 2 of the pt specific tumor mutation fragments detected in cfDNA. Association of ctDNA with response and survival was analyzed using logistic and Cox regressions with pCR and DRFS as endpoints. Median follow-up was 2.8 years. Results: Detection of ctDNA decreased over time (P arm: T0-81%, T1-50%, T2-19%, T3-3%) and NAC only: T0-82%, T1-65%, T2-26%, T3-10%). ctDNA data at T0 and T1 was available for 96% (132/138) of pts in P arm or NAC only (Table). Among ctDNA+ patients at baseline, clearance at T1 was significantly associated with pCR (OR=1.92, ctDNA+/-; OR=0.27, ctDNA+/+; LR p<0.001). This association remained significant after adjustment for HR status and treatment (LR p<0.001) and P arm or NAC only (P: LR p=0.03; NAC: LR p=0.01). ctDNA data at T0, T1, and T2 was available for 86% (118/138) pts. (Table). Among all ctDNA+ pts at baseline, dynamics through T2 was associated with pCR (OR=1.44, ctDNA+/-/-; OR=0.33, ctDNA+/+/-, OR=0.12, ctDNA+/+/+; LR p=0.0011). This association remained significant when adjusted for HR status and treatment (LR p<0.001). Analysis within individual treatments showed significant association for NAC (LR p=0.040) and a non-significant trend in NAC+P (LR p=0.063), likely due to smaller sample size. All pts who achieved pCR were ctDNA- at T3 (n=34). Among those who failed to achieve pCR (n=81), DRFS was significantly better in ctDNA- (n=72/81; 20 in P and 52 in NAC) versus ctDNA+ pts (n=9/81; 1 in P and 8 in NAC) (adjusted HR 0.13; 95% CI 0.05-0.37). Conclusions: These exploratory results align with our previous findings that early clearance of ctDNA during NAC treatment was significantly associated with increased likelihood of achieving pCR. Additionally, we show that ctDNA clearance can be an early surrogate marker for therapy response assessment. Residual ctDNA after neoadjuvant treatment was a significant predictor of metastatic recurrence and death. Personalized monitoring of ctDNA during the course of NAC is feasible and provides information that can be combined with imaging and pathology, and may help to optimize decision making for de-escalation or escalation of therapy. Larger studies are ongoing. ctDNA dynamics and pCRctDNA status at T0 and T1 (n=132)ctDNA status at T0, T1, and T2 (n=118)ctDNA-/-ctDNA+/-ctDNA+/+ctDNA-/-/-ctDNA+/-/-ctDNA+/+/-ctDNA+/+/+Total, n (%)24 (18)28 (21)80 (61)22 (19)24 (20)43 (36)27 (23)pCR, n (%)9 (38)15 (54)11 (14)9 (41)12 (50)8 (19)2 (7)No pCR, n (%)15 (63)13 (46)69 (86)13 (59)12 (50)35 (81)25 (93) Citation Format: Mark Jesus M Magbanua, Denise Wolf, Derrick Renner, Svetlana Shchegrova, Lamorna Brown Swigart, Christina Yau, Gillian Hirst, Hsin-Ta Wu, Ekaterina Kalashnikova, Antony Tin, Amy Delson, Douglas Yee, Angela DeMichele, Raheleh Salari, Angel Rodriguez, Bernhard Zimmermann, Himanshu Sethi, Alexey Aleshin, Paul Billings, Laura Esserman, Minetta Liu, Rita Nanda, Laura van ‘t Veer, I-SPY 2 Investigators. Personalized ctDNA as a predictive biomarker in high-risk early stage breast cancer (EBC) treated with neoadjuvant chemotherapy (NAC) with or without pembrolizumab (P) [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PD9-02.

TPS1136 Background: Hsp90 is a molecular chaperone protein required for the stabilization and activation of many proteins, referred to as Hsp90 ‘clients’, including those commonly implicated in breast tumorigenesis such as HER2, EGFR, ER, PI3K, AKT, P53 and VEGFR. Ganetespib is a novel triazolone inhibitor of Hsp90 being studied in over 20 clinical trials, with over 700 patients treated to date. Ganetespib is ~50x more potent than 1st-generation Hsp90 inhibitors, and has been well tolerated in clinical trials with a favorable safety profile. Mild to moderate, transient diarrhea is the most common adverse event associated with ganetespib infusion and is manageable with appropriate supportive care. Ganetespib has shown activity in preclinical models of HER2+, ER+/PR+ and triple negative breast cancer (TNBC). In a phase I trial, ganetespib demonstrated single-agent clinical activity in HER2+ disease with an objective response rate (ORR) of 15% and a disease stabilization rate of 46% in heavily pretreated patients. This efficacy-screening study is designed to provide further evidence of ganetespib activity and identify potentially predictive biomarkers in metastatic breast cancer. Methods: The ENCHANT-1 trial is an international, first-line Phase II study in two cohorts of breast cancer patients: Cohort A, HER2 amplified (n=35), and Cohort B, TNBC (n=35). HER2+ patients must have received prior anti-HER2 therapy in the adjuvant setting. Patients are treated with ganetespib at 150 mg/m2 twice weekly on a three out of four-week regimen. Primary endpoint: ORR assessed using RECIST1.1 criteria. Key secondary endpoints include metabolic effects as assessed by PET/CT at week 3. Tumor genetic signature and proteomic profiling are performed on patient’s tumors in an effort to develop biomarkers of response. At the time of submission 6 patients have been enrolled into this study. Clinical trial information: NCT01677455.

Purpose We previously reported the eradication of human epidermal growth factor receptor 2 (HER2)– amplified human xenografts in mice by inhibition of the HER2 pathway with lapatinib and trastuzumab to block all homo- and heterodimer signaling as well as by blockade of estrogen receptor (ER) when expressed. In this clinical trial, we sought to translate these findings to patients using targeted therapy without chemotherapy. Patients and Methods Women with stages II to III HER2-positive breast cancers were eligible. They received trastuzumab once per week (4 mg/kg loading, then 2 mg/kg) and lapatinib 1000 mg once per day for 12 weeks. Women with ER-positive tumors also received letrozole (plus a luteinizing hormone–releasing hormone [LHRH] agonist if premenopausal). Pathologic response was assessed by ER status. Biopsies were obtained at baseline, weeks 2 and 8, and time of surgery. Results Sixty-six patients were enrolled, and 64 were eligible and evaluable for response. Median tumor size was 6 cm (range, 1.5 to 30 cm). Adverse events were mainly grades 1 to 2 (GI, 63%; skin, 46%). Grade 3 metabolic, GI, and liver (18%; 12 patients) and grade 4 liver toxicities (one patient) were also observed. Overall, in-breast pathologic complete response (pCR; yp T 0 - is ) was 27% (ER positive, 21%; ER negative, 36%). The rate of low-volume residual disease ( yp T 1a-b ) was 22% (ER positive, 33%; ER negative, 4%). Conclusion In patients with locally advanced HER2-positive breast cancer, our approach of targeted therapy only resulted in a high pCR rate without chemotherapy. Our data support the hypothesis that selected patients with HER2-positive tumors may not need chemotherapy, and more-complete blockade of HER receptors and ER is an effective strategy worthy of further study.