Circulating Tumor DNA Levels Research Articles

Cancer treatment monitoring using cell-free DNA fragmentomes.

Circulating cell-free DNA (cfDNA) assays for monitoring individuals with cancer typically rely on prior identification of tumor-specific mutations. Here, we develop a tumor-independent and mutation-independent approach (DELFI-tumor fraction, DELFI-TF) using low-coverage whole genome sequencing to determine the cfDNA tumor fraction and validate the method in two independent cohorts of patients with colorectal or lung cancer. DELFI-TF scores strongly correlate with circulating tumor DNA levels (ctDNA) (r = 0.90,p < 0.0001, Pearson correlation) even in cases where mutations are undetectable. DELFI-TF scores prior to therapy initiation are associated with clinical response and are independent predictors of overall survival (HR = 9.84, 95% CI = 1.72-56.10,p < 0.0001). Patients with lower DELFI-TF scores during treatment have longer overall survival (62.8 vs 29.1 months, HR = 3.12, 95% CI 1.62-6.00,p < 0.001) and the approach predicts clinical outcomes more accurately than imaging. These results demonstrate the potential of using cfDNA fragmentomes to estimate tumor burden in cfDNA for treatment response monitoring and clinical outcome prediction.

Preoperative liquid biopsy for optimal patient selection in metastatic colorectal cancer

ObjectiveIn this pilot study, we sought to determine if preoperative circulating tumor DNA could be a useful predictor to avoid futile metastasectomy, predict early postoperative recurrence, and determine optimal chemotherapy duration during the management of patients with resectable metastatic colorectal cancer. MethodsPatients from 2021 to 2023 were enrolled prospectively and evaluated with circulating tumor DNA preoperatively and postoperatively for detection of recurrence. Clinicopathologic and treatment factors as well as disease-free survival were compared between those with undetectable versus detectable preoperative circulating tumor DNA. ResultsTwenty-eight patients were evaluated, with a median follow-up time of 24 months. The median preoperative circulating tumor DNA level was 0.16 MTM/mL [0.00, 2.30]. Of the 10 patients (40%) with a preoperative circulating tumor DNA level of zero, 5 patients (50%) recurred between 4 and 18 months postoperatively. Among the 18 patients whose disease recurred, 10 patients (56%) had circulating tumor DNA detected postoperatively. Median change between preoperative and postoperative circulating tumor DNA levels was 0.00 [–0.02, 0.05] in those who did not recur and 0.00 [–7.04, 0.00] in those who recurred. When disease-free survival was evaluated by detectable versus undetectable preoperative circulating tumor DNA levels, there was no difference in disease-free survival estimates (P value = .11). On univariate Cox proportional hazards analysis, the preoperative circulating tumor DNA level, change between preoperative and postoperative circulating tumor DNA levels, and postoperative circulating tumor DNA levels did not influence disease-free survival. However, those with detectable postoperative circulating tumor DNA were 3.96 (95% confidence interval 1.30–12.06) times as likely to recur compared to those with undetectable postoperative circulating tumor DNA. ConclusionNew technologies including use of circulating tumor DNA may help better predict which patients with colorectal liver metastases will undergo futile surgery. Our preliminary findings suggest that postoperative, and not preoperative, circulating tumor DNA is predictive of recurrence following metastasectomy. Use of circulating tumor DNA in guiding operative management should be done in conjunction with high-quality imaging and other serologic markers to determine which patients with colorectal liver metastases are likely to receive durable benefit from operative intervention.

Longitudinal Analyses of Circulating Tumor DNA for the Detection of EGFR Mutation-Positive Advanced NSCLC Progression During Treatment: Data From FLAURA and AURA3

IntroductionEGFR tyrosine kinase inhibitor (EGFR-TKI)-sensitizing and -resistance mutations may be detected in plasma through circulating tumor DNA (ctDNA). Circulating tumor DNA level changes reflect alterations in tumor burden and could be a dynamic indicator of treatment effect. This analysis aimed to determine whether longitudinal EGFR-mutation ctDNA testing could detect progressive disease (PD) before radiologic detection. MethodsThis was a retrospective, exploratory ctDNA analysis in two phase 3 trials (FLAURA, NCT02296125; AURA3, NCT02151981). Patients had treatment-naïve (FLAURA) or EGFR-TKI pre-treated (AURA3) advanced NSCLC with EGFR mutations and on-study PD (RECIST [Response Evaluation Criteria in Solid Tumors]), with a baseline ctDNA result and EGFR-mutation ctDNA monitoring beyond Cycle 3 Day 1. Patients received osimertinib versus comparator EGFR-TKIs (FLAURA) or chemotherapy (AURA3). Outcomes included time from ctDNA PD to RECIST PD and the first subsequent treatment (FLAURA only). ResultsCirculating tumor DNA PD preceded or co-occurred with RECIST-defined PD in 93 out of 146 patients (64%) in FLAURA and 82 out of 146 patients (56%) in AURA3. Median time from ctDNA PD to RECIST-defined PD (mo) was 3.4 and 2.6 in the osimertinib and comparator EGFR-TKI arms (FLAURA) and 2.8 and 1.5 in the osimertinib and chemotherapy arms (AURA3). In FLAURA, the median time from ctDNA PD to the first subsequent treatment (mo) was 6.0 and 4.7 in the osimertinib (n = 51) and comparator EGFR-TKI arms (n = 70). ConclusionsAmong patients with EGFR mutation-positive advanced NSCLC receiving EGFR-TKI or chemotherapy with ctDNA data and RECIST-defined PD, ctDNA PD preceded/co-occurred with RECIST-defined PD in approximately 60% of cases. Longitudinal ctDNA monitoring may detect PD before radiologic PD.

Durable complete responses to PD-1 blockade alone in mismatch repair deficient locally advanced rectal cancer.

LBA3512 Background: Early results have demonstrated that locally advanced mismatch repair deficient rectal cancers can become undetectable with PD-1 blockade alone and do not require chemotherapy, radiation, or surgery. Yet, the durability of this approach is unknown. Methods: We enrolled 47 mismatch repair deficient rectal cancers to a phase II study of 6-months of dostarlimab, a PD-1blocking monoclonal antibody. Co-primary endpoints were response rate that was previously met and the sustained clinical complete response rate, which has not yet been reported. A sustained clinical complete response was defined as complete pathologic response at surgery or no evidence of tumor by MRI, endoscopy, and digital rectal exam for at least 12 months following completion of therapy. If 13 or more patients achieved a sustained clinical complete response out of the first 30 patients, the study would be deemed successful. Results: All of the 41 patients who completed treatment achieved a clinical complete response. No patients required any additional therapy, and no patients experienced local or distant disease recurrence. Twenty patients achieved a sustained clinical complete response with a median follow-up of 28.9 months (95% CI 22.9 -37.1) from first treatment, which satisfied the second co-primary endpoint. No serious adverse events greater than grade 2 were observed. Ultrasensitive tumor-informed circulating tumor DNA levels and tumor bed biopsies normalized earlier than endoscopy, MRI or PET/CT. Conclusions: PD-1 blockade for 6-months alone yields durable recurrence-free responses in locally advanced mismatch repair deficient rectal cancer without the need for chemotherapy, radiation, or surgery. Clinical trial information: NCT04165772 .

Phase I/II study of TROP2 CAR engineered IL15-transduced cord blood-derived NK cells delivered intraperitoneally for the management of platinum resistant ovarian cancer, mesonephric-like adenocarcinoma, and pancreatic cancer.

TPS5626 Background: Novel treatments are needed for patients with ovarian, pancreatic, and mesonephric-like adenocarcinoma (MLA) that has recurred or progressed after initial treatment, as current standard of care therapies in these settings result in low response rates. Chimeric antigen receptor-transduced natural killer (CAR-NK) cells have emerged as a therapeutic alternative to CAR-T cells, with decreased toxicity and enhanced feasibility as an “off-the-shelf” therapy. TROP2, or trophoblast cell-surface antigen 2, is a transmembrane calcium-signal transducer that is overexpressed in many cancer types and associated with poor clinical outcomes. Recent studies have demonstrated TROP2 as a promising target for adoptive cell therapy in breast and gastric cancers. An intraperitoneal route of adoptive cell therapy delivery may provide superior disease control and decreased toxicity in these target cancers with predisposition for intra-abdominal/peritoneal involvement. Pre-clinical studies have established the efficacy and safety of TROP2 CAR NK cells in ovarian and pancreatic cancers. Methods: This is a phase I/II study of the intraperitoneal delivery of TROP2-CAR/IL-15 transduced cord blood (CB)-NK cells for recurrent/progressive ovarian cancer, pancreatic cancer, and MLA (NCT05922930). Subjects must have disease present in the peritoneal cavity or retroperitoneal lymph nodes and tumors must demonstrate at least 1+ TROP2 expression by immunohistochemistry. The primary endpoints are toxicity rates and defining the recommended phase II dose (RP2D). Key secondary endpoints include treatment efficacy, circulating tumor DNA levels, serial characterization of the immune microenvironment, and patient-reported outcomes. There are four possible dose levels ranging from 8.0x106 to 4.0x109 cells. We will enroll patients from the three disease cohorts using the Bayesian optimal interval (BOIN) design to find the maximum tolerated dose and RP2D, with a maximum sample size of 21. Once the R2PD is chosen, we will enroll up to 10 patients within each disease cohort to further evaluate safety and efficacy. Subjects enrolled will be admitted to the hospital, receive lymphodepleting chemotherapy (fludarabine 30 mg/m2 and cyclophosphamide 300mg/m2) on days -5 to -3, and will receive a single dose of cryopreserved and thawed intraperitoneal TROP2-CAR/IL15-transduced CB-NK cells on day 0. The dose-limiting toxicity window will be from day 0 until day 28. Severity of adverse events will be graded according to the National Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE) version 5. The first patient on this trial was treated in January 2024. Clinical trial information: NCT0592293 .

Abstract PS15-03: Vepdegestrant, a PROteolysis TArgeting Chimera (PROTAC) estrogen receptor (ER) degrader, plus palbociclib in ER–positive/human epidermal growth factor receptor 2 (HER2)–negative advanced breast cancer: phase 1b cohort

Abstract Background: Vepdegestrant (ARV-471) is an oral PROTAC ER degrader. In a phase 1/2 study (NCT04072952), vepdegestrant monotherapy had a favorable safety profile and encouraging clinical activity, and showed robust ER degradation. The phase 1b cohort of this study is evaluating vepdegestrant in combination with the cyclin-dependent kinase (CDK)4/6 inhibitor palbociclib (palbo). In xenograft models, vepdegestrant plus palbo showed substantially greater tumor growth inhibition vs fulvestrant plus palbo, supporting investigation in patients with breast cancer. Methods: Eligible patients for the phase 1b combination cohort had ER+/HER2- locally advanced/metastatic breast cancer and had received ≥1 prior endocrine therapy and ≤2 chemotherapy regimens for advanced disease; prior CDK4/6 inhibitor treatment was permitted. Vepdegestrant was given orally once daily (QD) continuously at doses of 180 mg (n=2), 200 mg (n=21), 400 mg (n=3), or 500 mg (n=20); palbo 125 mg was given orally QD for 21 days followed by 7 days off treatment in 28-day cycles. The primary endpoints were dose-limiting toxicities (DLTs) in the first cycle and safety (adverse events [AEs] and laboratory abnormalities). Enrollment in these 4 dose levels is complete; we report data as of June 6, 2023. Results: Across 46 patients in the phase 1b cohort, 45 (97.8%) patients were female with a median age of 62.0 y (range: 29–78). Patients had received a median of 4 prior therapies (range: 1–11) in any setting, including 87.0% prior CDK4/6 inhibitors (78.3% prior palbo), 80.4% prior fulvestrant, and 76.1% prior chemotherapy (45.7% in the metastatic setting). There were no DLTs. Treatment-emergent AEs (TEAEs) leading to dose reductions or discontinuation of vepdegestrant occurred in 5 and 4 patients, respectively. TEAEs leading to dose reductions or discontinuation of palbo occurred in 34 and 8 patients, respectively. Grade 3/4 treatment-related AEs (TRAEs) to either vepdegestrant or palbo in ≥10% of patients were neutropenia (89.1%), decreased white blood cell count (15.2%), and decreased platelet count (10.9%); there were no grade 5 TRAEs and no patients had febrile neutropenia. The clinical benefit rate (rate of confirmed complete response, partial response, or stable disease ≥24 wks) in patients treated with vepdegestrant plus palbo was 63.0% (95% CI: 47.5–76.8). The objective response rate in evaluable patients with measurable disease at baseline (n=31) was 41.9% (95% CI: 24.5–60.9). Pharmacokinetics (PK) showed dose-dependent exposure for vepdegestrant, consistent with data for vepdegestrant administered as monotherapy; palbo exposure was similar across dose levels of vepdegestrant and modestly higher compared with historical palbo PK data. Circulating tumor DNA levels were evaluated in patients who received vepdegestrant 200 mg QD plus palbo and demonstrated substantial and sustained decreases in ESR1 mutant allele fraction across multiple treatment cycles. Conclusions: The combination of vepdegestrant plus palbo showed promising clinical activity in heavily pretreated patients with ER+/HER2- advanced breast cancer who had received extensive prior treatment. The safety profile of vepdegestrant plus palbo was generally consistent with the known safety profiles of the 2 agents except for an increased occurrence of grade 3/4 neutropenia, which was readily managed with laboratory monitoring and dose reductions of palbo. There is an ongoing study lead-in to the global VERITAC-3 study (NCT05909397) that is evaluating 2 doses of palbo (100 mg and 75 mg) in combination with vepdegestrant 200 mg QD to determine the recommended phase 3 combination to compare with letrozole plus palbo as first-line treatment for ER+/HER2- advanced breast cancer. Citation Format: Erika Hamilton, Rinath Jeselsohn, Sara Hurvitz, Dejan Juric, Hyo Han, Melinda Telli, George Zahrah, Rita Nanda, Yuanyuan Zhang, Weiwei Tan, Elizabeth Duperret, Eric Zhi, Cecile Mather, Anne Schott. Vepdegestrant, a PROteolysis TArgeting Chimera (PROTAC) estrogen receptor (ER) degrader, plus palbociclib in ER–positive/human epidermal growth factor receptor 2 (HER2)–negative advanced breast cancer: phase 1b cohort [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 PS15-03.

Abstract PO3-05-08: Updated results from VERITAC evaluating vepdegestrant, a PROteolysis TArgeting Chimera (PROTAC) estrogen receptor (ER) degrader, in ER–positive/human epidermal growth factor receptor 2 (HER2)–negative advanced breast cancer

Abstract Background: Vepdegestrant (ARV-471) is an oral PROTAC ER degrader with activity toward wild-type and mutant ER. The phase 2 expansion (VERITAC) of a phase 1/2 study (NCT04072952) tested 2 vepdegestrant doses (200 mg once daily [QD] and 500 mg QD) in heavily pretreated patients with ER+/HER2- advanced breast cancer. Vepdegestrant 200 mg QD was selected as the phase 3 monotherapy dose based on comparable efficacy and favorable tolerability vs 500 mg QD and robust ER degradation (data cutoff: Jun 6, 2022). We present updated data for the vepdegestrant 200 mg QD cohort after 12 additional months of follow-up. Methods: Vepdegestrant was administered to patients with ER+/HER2- locally advanced/metastatic breast cancer who had received ≥1 prior endocrine therapy for ≥6 months, ≥1 cyclin-dependent kinase (CDK)4/6 inhibitor, and ≤1 chemotherapy regimen. The primary endpoint was clinical benefit rate (CBR; rate of confirmed complete response, partial response, or stable disease ≥24 weeks). Results: As of Jun 6, 2023, 35 patients received vepdegestrant 200 mg QD; 34 (97.1%) were female and median age was 63 y (range: 42–79). Patients had received a median of 4 prior regimens (range: 1–9) in all settings and 3 prior regimens (range: 0–7) in the metastatic setting; 100% had prior CDK4/6 inhibitors, 88.6% had prior aromatase inhibitors, 74.3% had prior fulvestrant, and 74.3% had prior chemotherapy (45.7% in metastatic setting). CBR with vepdegestrant 200 mg QD was 37.1% (95% CI: 21.5–55.1) in all evaluable patients (n=35) and the objective response rate was 8.3% (95% CI: 1.0–27.0) among 24 patients with measurable disease at baseline. Median progression-free survival in all evaluable patients was 3.5 months (95% CI: 1.8–8.2). As of the data cutoff date, 14 patients in the 200 mg QD cohort received treatment for ≥24 weeks (4 for ≥48 weeks) with 1 patient ongoing. No patients required a dose reduction due to a treatment-emergent adverse event (TEAE); 2 (5.7%) patients had a TEAE that led to vepdegestrant discontinuation (grade 3 QT prolongation and grade 3 anemia). The most common treatment-related adverse events (≥10%) were fatigue (43%), hot flush (20%), nausea (17%), arthralgia (11%), increased aspartate aminotransferase (11%), and increased blood alkaline phosphatase (11%); all were grade 1/2. Substantial on-treatment decreases in mutant ESR1 circulating tumor DNA levels were observed with vepdegestrant 200 mg QD and sustained for multiple treatment cycles. Conclusions: With 12 months of additional follow-up from the first data report, durable clinical activity with vepdegestrant 200 mg QD was seen in heavily pretreated patients with ER+/HER2- advanced breast cancer, in addition to sustained reduction in circulating mutant ESR1 tumor DNA levels. Vepdegestrant 200 mg QD continued to show a favorable safety profile. The ongoing global, randomized phase 3 VERITAC-2 study (NCT05654623) is evaluating vepdegestrant 200 mg QD vs intramuscular fulvestrant in patients with ER+/HER2- advanced breast cancer after prior combination CDK4/6 inhibitor therapy and endocrine therapy. Citation Format: Sara Hurvitz, Anne Schott, Cynthia Ma, Rita Nanda, George Zahrah, Natasha Hunter, Antoinette Tan, Melinda Telli, Jesus Anampa Mesias, Rinath Jeselsohn, Pamela Munster, Eric Zhi, Elizabeth Duperret, Cecile Mather, Erika Hamilton, Hyo Han. Updated results from VERITAC evaluating vepdegestrant, a PROteolysis TArgeting Chimera (PROTAC) estrogen receptor (ER) degrader, in ER–positive/human epidermal growth factor receptor 2 (HER2)–negative advanced 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 PO3-05-08.

Advancing Evidence Generation for Circulating Tumor DNA: Lessons Learned from A Multi-Assay Study of Baseline Circulating Tumor DNA Levels across Cancer Types and Stages.

Circulating tumor DNA (ctDNA) holds promise as a biomarker for predicting clinical responses to therapy in solid tumors, and multiple ctDNA assays are in development. However, the heterogeneity in ctDNA levels prior to treatment (baseline) across different cancer types and stages and across ctDNA assays has not been widely studied. Friends of Cancer Research formed a collaboration across multiple commercial ctDNA assay developers to assess baseline ctDNA levels across five cancer types in early- and late-stage disease. This retrospective study included eight commercial ctDNA assay developers providing summary-level de-identified data for patients with non-small cell lung cancer (NSCLC), bladder, breast, prostate, and head and neck squamous cell carcinoma following a common analysis protocol. Baseline ctDNA levels across late-stage cancer types were similarly detected, highlighting the potential use of ctDNA as a biomarker in these cancer types. Variability was observed in ctDNA levels across assays in early-stage NSCLC, indicative of the contribution of assay analytical performance and methodology on variability. We identified key data elements, including assay characteristics and clinicopathological metadata, that need to be standardized for future meta-analyses across multiple assays. This work facilitates evidence generation opportunities to support the use of ctDNA as a biomarker for clinical response.

Phase I Study of Response-Adapted Treatment with Venetoclax, Obinutuzumab, and Magrolimab (VENOM) in Relapsed and Refractory Indolent B-Cell Malignancies

Background and Significance Targeted agents and immunotherapy have changed the treatment landscape for follicular lymphoma (FL), mantle cell lymphoma (MCL), marginal zone lymphoma (MZL), and chronic lymphocytic leukemia (CLL), but indefinite therapy leads to cumulative toxicity and excessive cost. CD47 is a checkpoint for the innate immune system providing an inhibitory signal to phagocytic macrophages and a rational therapeutic target in B-cell lymphoma. Magrolimab is a fully humanized IgG4 anti-human CD47 antibody, with high activity in FL when combined with rituximab (Advani NEJM 2018). Our objective is to test the safety of adding escalating doses of venetoclax to magrolimab and obinutuzumab in a response-adapted study design with planned dose expansion cohorts (www.clinicaltrials.govidentifier NCT04599634). Study Design and Methods Patients with grade 1-3A FL, MCL, MZL, or CLL relapsed after and/or refractory to ≥2 prior lines of therapy are eligible. Pts with FL are eligible after 1 prior therapy if FLIPI ≥2 or disease progression within 24 months of the end of the last therapy. Pts with MCL are eligible after 1 prior therapy if blastoid histology, 17p deletion, TP53 mutation, Ki67 ≥30%, or received Bruton's tyrosine kinase inhibitor (BTKi) as first-line therapy. Pts with CLL are eligible after 1 prior therapy if 17p deletion, TP53 mutation, or received both a BTKi and a BCL2 inhibitor. Eligibility includes age ≥18 and adequate organ function unless dysfunction secondary to lymphoma. A positive direct antiglobulin test without hemolytic anemia is allowed. Patients with a history of hemolytic anemia or autoimmune thrombocytopenia within 3 months of enrollment are excluded. No washout period is required for prior anti-lymphoma treatment. Active HIV, CMV, and hepatitis B or C are excluded. The safety of venetoclax, obinutuzumab, and magrolimab will first be determined in 2 dose-finding cohorts of up to 24 pts (Cohort 1: 6-12 pts with FL and Cohort 2: 6-12 pts with MZL, MCL, or CLL). During dose-finding, all pts start triplet therapy with venetoclax, obinutuzumab, and magrolimab (Figure 1). Magrolimab IV is administered at a 1mg/kg priming dose on D1 of the first cycle, followed by 30mg/kg x 3 weekly loading doses, then 30 mg/kg on D1 of each 4-wk cycle. Obinutuzumab IV is administered at 100mg on D1, 900mg on D2, and 1000mg on D8 and D15 of the first cycle, followed by 1000mg on D1 of each 4-wk cycle. Pts with FL receive venetoclax 800mg (DL1) daily throughout therapy duration, whereas pts with MZL, MCL, and CLL start venetoclax at 20mg with weekly escalation to 400mg (DL1) over 5 weeks. Dose-limiting toxicity is assessed during the first 4 wks for FL, and the first 5 wks for MZL, MCL, and CLL. If ≥2 of 6 pts in either arm experience DLT, 6 additional pts will be enrolled to the respective arm at DL(-1) of venetoclax (600mg for FL and 200mg for MZL, MCL, and CLL). After dose-finding is completed, expansion cohorts of each histology will first receive magrolimab and obinutuzumab for two 4-wk cycles in a window for translational research. On-treatment tumor biopsies are optional during the window. After the window, venetoclax will be added at the dose determined during dose-finding. FDG-PET and CT scans are performed at baseline, after window, and after cycles 3 and 6 of triplet therapy. During both dose-finding and dose-escalation, pts with complete response (CR) after 6 cycles of triplet therapy will stop therapy. If these pts relapse, they can be retreated with an additional 6 cycles of triplet therapy. Pts with partial response (PR) after 6 cycles of triplet therapy receive an additional 6 cycles of triplet therapy. All pts stop treatment after 12 cycles. The primary objective is safety, with secondary endpoints of overall response rate, duration of response, and PFS. Exploratory objectives include the identification of a molecular signature that predicts response to magrolimab and obinutuzumab, and correlation of response with circulating tumor DNA levels.

Circulating DNA and frequency of colorectal cancer brain metastases in a presumed high-risk group

This explorative prospective observational pilot study investigated if suggested risk factors, rectal cancer and lung metastases, could add to a relevant detection rate of asymptomatic brain metastases (BM) from colorectal cancer (CRC). Secondary, prognostic biological aspects were investigated by translational analysis of plasma samples. The study enrolled patients with rectal cancer and lung metastases. At inclusion, patients underwent a standard MRI scan of the brain. Cell-free DNA (cfDNA) level was measured by a direct fluorescence assay (DFA), and circulating tumor DNA (ctDNA) by ddPCR. BM was detected in one of twenty-nine included patients. Patients had higher cfDNA levels than healthy subjects (p < 0.01). Patients with the primary tumor in situ had higher cfDNA levels than those with resected primary tumor (p < 0.01). Patients with liver involvement had higher cfDNA levels (p = 0.12) and circulating tumor DNA levels (p = 0.01) than those without liver involvement. In conclusion, the modest incidence of BM does not justify routine MRI of the brain in this selected population. cfDNA by DFA could be a valuable tool when planning treatment and follow-up for CRC patients. Future studies should focus on identifying further characteristics and biomarkers associated with a high risk of BM, enhancing the possibility for early intervention.

Mechanisms of sensitivity to platinum-based chemotherapy in PD-1 blockade-refractory head and neck cancer.

e18003 Background: Our clinical observation from recurrent/metastatic head and neck patients who treated with platinum based combination after progression on pembrolizumab showed a striking response rate of 80% (8 out of 10 patients), this impressive ORR is dramatically higher than the historical ORR of 27% in the first-line setting. Our mouse model of ‘immune-cold’ head and neck cancer is developed to investigate the mechanism of sensitivity to platinum- based chemotherapy in PD-1 blockade-refractory head and neck cancer. Methods: For ‘immune-cold’ syngeneic model of HNSCC, C57BL/6 mice were injected with 5 × 104 MOC2 tumor cells in the right flank. After 11 days, mice with palpable tumors were randomized and treated concurrently with 4 groups (n = 5 per group): control, anti–PD1 antibody (200 mcg three times/week × 3 cycles), cisplatin (3mg/kg) +paclitaxel (5mg/kg) once a week x 3 cycles, or anti-PD1 antibody (200 mcg three times/week × 1 cycle) followed by cisplatin (3mg/kg) + paclitaxel (5mg/kg) once a week x 2 cycle. Cisplatin + paclitaxel arm received total of 4 cycles of treatment, while PD-1 followed by cisplatin and paclitaxel arm received total of 3 cycles of cisplatin and paclitaxel, this schedule was set up to maintain every 3 week regimen with same duration of treatment time to mimic patient’s treatment schedule in clinic setting. Tumor volume was measured 3 times per week. Results: Our initial pilot mouse model study showed similar tumor response seen in patient population. Starting on D24, average tumor size of PD1 inhibitor followed by cisplatin+paclitaxel group is significantly decreased compared to PD1 inhibitor or cisplatin+paclitaxel group and the difference is statistically significant. Most of mice in control and PD1 inhibitor group died at day 24 due to tumor progression. Our IHC data showed that the expression levels of immune markers such as CD8+, CD4+ and PDL1 in tumors treated with PD1 inhibitor followed by cisplatin and paclitaxel were increased, compared to almost no or scant expression (CD8+, CD4+) and lower expression (PDL1) in tumors treated with cisplatin and paclitaxel alone. With our expansion cohort, we will be further exploring key changes in immune signatures using both peripheral blood samples and tumor blocks for flow cytometry (myeloid/lymphoid subtypes, alterations in cytokine expression and circulating tumor DNA levels) and RNA sequencing analysis. Conclusions: We successfully established an ‘immune-cold’ mouse model of head and neck and reproduced similar tumor response seen in clinic. Preliminary data showing increased expression of immune makers such as CD8+, CD4+ and PDL warrants further investigation on tumor immune microenvironment remodeling as a potential mechanism of sensitivity to platinum-based chemotherapy in PD-1 blockade-refractory head and neck cancer.

Failure rates of mutation-based ctDNA assays in lung cancer treatment monitoring.

e18752 Background: Despite the wide adoption of noninvasive liquid biopsy approaches for cancer genotyping, little is known about the longitudinal performance of these assays for monitoring therapeutic responses in patients with advanced disease. Here, we report results of a pooled analysis that collects existing evidence regarding the failure rates of circulating tumor DNA (ctDNA) assays designed for therapeutic monitoring in patients with advanced or metastatic lung cancer. Methods: We searched PubMed for original studies published between February 2012 and January 2022, following these inclusion criteria: (1) Adults older than 18 years old with advanced or metastatic lung cancer treated with chemotherapy, targeted therapy, or immunotherapy; (2) Tumor-informed or plasma-only circulating tumor DNA assays based on droplet digital PCR (ddPCR) or targeted deep sequencing technologies for the detection of tumor-specific allele fractions; (3) Measurement of circulating tumor DNA levels at sequential timepoints. We defined failures as a lack of detectable mutant allele fraction (MAF) in patients with metastatic lung cancer in samples collected before treatment initiation. Two reviewers independently screened studies, extracted data, assessed the risk of bias, and evaluated the quality of evidence. Divergences were resolved by a third independent reviewer reaching a consensus. Study quality assessment covered: (1) representativeness of patient population, (2) risk of funding bias, (3) description of ctDNA analysis and outcomes, and (4) statistical quality and interpretation. Results: From 142 studies retrieved by an automated PubMed query, we extracted data from 42 studies which fulfilled the eligibility criteria - 11 registered trials, 31 prospective/retrospective cohorts. MAF levels in the circulation were measured using PCR-based assays (23/42, 55%); the remainder used NGS-based approaches (19/42, 45%). The median number of targeted genes was 1 (range 1-6) vs 73 (range 36-214), respectively. The median number of samples analyzed per study was 79 (range 3-334). On average, 31% of samples collected before treatment did not have a detectable MAF in any of the target genes analyzed, despite the high disease burden typically experienced in patients with metastatic lung cancer. Only 57% of PCR-based and 78% NGS-based studies succeeded in providing molecular response assessment metrics. We identified 10/42 studies with critical quality assessment concerns and 18 studies had funding provided by a company with investments in the commercial cfDNA assay. Conclusions: Available liquid biopsy assays that report tumor-specific mutations have a high rate of failure for measuring disease burden and response outcomes during therapy. Approaches that could be reliably used for monitoring patients with advanced cancers undergoing treatment are needed to improve patient care.

Abstract 6240: The potent quadruplex-binding compound QN-302 shows anti-tumor activity as a monotherapy in an orthotopic in vivo model of pancreatic cancer

Abstract The compound QN-302, a tetra-substituted naphthalene diimide derivative has single-digit nM anti-proliferative activity in a panel of human pancreatic cancer (PDAC) cell lines (Ahmed et al., ACS Med Chem Lett, 2020, 11, 1634-1644). It has significant anti-tumor activity in the MIA-PACA2 xenograft model for PDAC and in the genetic KPC model. We now report that this compound also shows significant mono-therapy anti-tumor activity in an orthotopic model for PDAC. Female athymic nude mice bearing orthotopically implanted pancreatic BxPC-3 cells were dosed with 1 x weekly IV QN-302 at 0.5 and 1.0 mg/kg, over a period of 21 days. A separate group of mice was treated with Gemcitabine twice weekly IV during this period, at a dosage of 15 mg/kg. Blood samples from animals were collected on a weekly basis and were used to detect and quantify circulating tumor DNA as a method of following treatment efficacy. In line with previous studies QN-302 was well-tolerated at 0.5 and 1.0 mg/kg with no adverse effects on animal health or behavior noted during the study. Circulating tumor DNA levels were significantly less than vehicle controls in gemcitabine-treated animals from day 7 and QN-302 (1.0 mg/kg) treated animals from day 14 of treatment. Survival was significantly increased in gemcitabine and QN-302 (1.0 mg/kg) QW treatment groups. Statistically significant efficacy was observed in gemcitabine and QN-302 (1.0 mg/kg) treated animals. Examination of blood chemistry and biochemistry of treated animals did not indicate any adverse effects due to QN-302. This orthotopic model is the 4th in vivo study in a pancreatic cancer model showing anti-tumor activity for QN-302, further confirming the potential of this compound for human disease. QN-302 is currently in an advanced stage of pre-IND development by Qualigen Inc. Citation Format: Nicole Williams, Danielle Santos, Jenny Worthington, Ahmed Ahmed, Tariq Arshad, Stephen Neidle. The potent quadruplex-binding compound QN-302 shows anti-tumor activity as a monotherapy in an orthotopic in vivo model of pancreatic cancer. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6240.

Abstract 3123: A method for quantifying circulating tumor DNA level and molecular response using methylome sequencing

Abstract Background: Circulating tumor DNA (ctDNA) level and the change in level at a subsequent time point (e.g. on-treatment change from baseline or postoperative changes through time) are promising tools for predicting patient prognosis and response to therapy. Existing methods use somatic variant allele frequencies to quantify circulating tumor fractions (cTF). Their performance can be limited by the number of detectable somatic alterations and the associated limit of detection (LoD), as well as interference from copy number variation and non-tumor alterations, such as clonal hematopoiesis. Here, we describe the LoD, precision and limit of quantitation (LoQ) of cTF level and change using GuardantINFINITY, a next generation sequencing panel covering over 800 genes with genome-wide methylation detection. Method: The cTF of a single sample is estimated from methylation signals across targeted regions of the GuardantINFINITY methylation panel, calibrated using internal training data. cTF change compares two or more samples from the same patient to identify patient-specific methylated regions, and compare the methylation signals of the paired regions. LoQ of cTF level and change were assessed in experimental titrations of advanced colorectal, breast, and lung cancer patient samples and cell line samples into cancer-free backgrounds at different target levels between 0.1%-0.5% cTF. LoD is defined as the lowest cTF level where &amp;gt;95% replicates were detected to have tumor-derived methylation signals. LoQ of cTF level or change is defined as the lowest cTF where the coefficient of variation (CV) across replicates is less than 30%. Accuracy of methylation based cTF compared to cTFs calculated from maximum VAF of somatic mutations was assessed on 1,400 clinical samples of colorectal and lung cancer patients (N=189, 372, 252 and 463 for stage I to IV). Results: Experimental titrations of cancer samples demonstrated a single-sample LoD of 0.05% cTF (lowest dilution level) and quantitative precision down to a LoQ of below 0.1%, compared to the LoQ of 0.3% estimated by somatic mutations. In paired clinical titration samples, the LoQ of methylation ctDNA level change was also below 0.1%, compared to the LoQ of ctDNA level change estimated by somatic mutations at 0.3-0.5%. In the 1,400 clinical samples, 64% had at least one somatic mutation detected, 90% had ct-DNA detected with methylation and 96% of these ct-DNA detected samples had cTF above the defined methylation LoQ. Among patients with both methylation and genomic signals identified, the methylation method quantified a similar cTF to those that were calculated using maximum somatic driver mutations (Pearson r=0.83). Conclusion: Methylome sequencing using GuardantINFINITY enables accurate and precise quantification of ctDNA level and change with a liquid-only approach, offering longitudinal ctDNA monitoring for more patients than previous methods. Citation Format: Sai Chen, Katie Quinn, Che-Yu Lee, Jun Zhao, Kyle Chang, Tingting Jiang, Shile Zhang, Carin Espenschied, Sara Wienke, Thereasa Rich, Indira Wu, Yvonne Kim, Xianxian Liu, Nageswara Alla, Dustin Ma, Giao Tran, Han-Yu Chuang. A method for quantifying circulating tumor DNA level and molecular response using methylome sequencing [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3123.

Abstract P3-07-13: The next generation oral selective estrogen receptor degrader (SERD) camizestrant (AZD9833) is active against wild type and mutant estrogen receptor α

Abstract Endocrine therapy forms the backbone treatment for patients with estrogen receptor (ER) positive tumors in both the adjuvant and metastatic setting. Aromatase inhibitors (AI) are the most common endocrine treatment option. Mutation of ESR1, the gene encoding ERα, is a common mechanism of resistance to AIs which leads to ligand independent activity of ERα. Camizestrant (AZD9833) is a next generation SERD and pure ER antagonist that is in Phase 3 trials (SERENA-4: NCT04711252; SERENA-6: NCT04964934). Here we report the preclinical and clinical activity of camizestrant in patients with ESR1 wild-type (ESR1wt) and mutant (ESR1m) tumors. The binding affinities of camizestrant, fulvestrant, and estradiol to wt ERα and ERα variants with mutations in the ligand binding domain were assessed. All three compounds exhibited reduced binding to mutant forms of ERα compared with wt ERα; the Y537S mutation had the greatest impact on binding. This was reflected in requirement for greater concentrations of camizestrant and fulvestrant to degrade and antagonize mutated ERα and to impact cellular proliferation in MCF-7 cells that expressed Y537S ESR1m compared to ESR1wt MCF-7 cells. Furthermore, while a 3 mg/kg dose of camizestrant achieved a maximal anti-tumor effect in a ESR1wt patient derived xenograft model, a 10 mg/kg was required for maximal effect in a D538G ESR1m model. Considering this difference between ESR1m and ESR1wt, pharmacokinetic/pharmacodynamic modelling of preclinical data predicted that a camizestrant dose of 75 mg would be maximally efficacious in patients with ESR1m tumors. Indeed, analysis of ESR1m circulating tumor DNA levels in patients from the SERENA-1 (NCT03616587) Phase 1 trial showed a clear effect of 14 days treatment with 75 mg camizestrant resulting in a &amp;gt;2-fold reduction in ESR1m variant allele frequency in 12/13 (92%) cases with complete clearance of ESR1m ctDNA in 7/13 (54%) cases. Interestingly, the clinical activity of camizestrant was higher in heavily pretreated patients with metastatic breast cancer with ESR1m tumors compared to those with no detectable mutation (ESR1m not detected). At a camizestrant dose of 75 mg, median progression-free survival was 8.3 months (maturity 12/15) in patients with ESR1m tumors compared to 5.6 months (8/9) in those with ESR1m not detected (data cut-off 6 October 2021). Camizestrant-induced ERα degradation was seen in both groups (mean reduction in H-score 42% in ESR1m tumors (n= 12 evaluable pairs) and 46% in tumors with ESR1m not detected (n=7)). Whole transcriptome analysis revealed a trend towards higher ERα activity at baseline in ESR1m tumors compared to ESR1m not detected; ERα activity reduced on treatment in both groups. Consistent with the clinical activity data, camizestrant induced more profound reductions in cell proliferation in ESR1m tumors compared to ESR1m not detected tumors (as seen by greater reductions in Ki67-positive tumor cells). These data demonstrate the activity of camizestrant in patients with ESR1m tumors. Clinical activity along with degradation and antagonism of the ERα is also seen in patients with tumors in which ESR1 mutations are not detected. In this heavily pre-treated Phase 1 patient population from SERENA-1, ESR1m may be a predictive biomarker to enrich for patients with maintained endocrine sensitivity. The SERENA-6 trial is investigating the efficacy and safety of camizestrant plus a CDK4/6 inhibitor in patients with metastatic breast cancer and detectable ESR1m. We acknowledge Helen Heffron, PhD, from InterComm International who provided medical writing support funded by AstraZeneca. Citation Format: Christopher Morrow, Larissa Carnevalli, Richard D. Baird, Tim Brier, Carmela Ciardullo, Natalie Cureton, Mandy Lawson, Robert McEwen, Myria Nikolaou, Anne Armstrong, Begoña Bermejo, Emiliano Calvo, Eva Ciruelos, Javier Garcia-Corbacho, Erika Hamilton, Jason Incorvati, Peter Kabos, Mafalda Oliveira, Manish R Patel, Manuel Ruiz-Borregó, Nicholas Turner, Chris Twelves, Christos Vaklavas, Danielle Carroll, Steven Ching, Nevena Cvetesic, Michelle DuPont, Lisa Gibbons, Alastair Mathewson, Rhiannon Maudsley, Pablo Morentin Gutierrez, Avinash Reddy, Jaime Rodriguez-Canales, Susana Ros, Dhivya Sudhan, Andy Sykes, David Whitson, Teresa Klinowska, Justin Lindemann. The next generation oral selective estrogen receptor degrader (SERD) camizestrant (AZD9833) is active against wild type and mutant estrogen receptor α [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 P3-07-13.

Selected Articles from This Issue

Shoushtari and colleagues report a pilot trial of ONCOS-102, a novel oncolytic adenovirus encoding GM-CSF, administered intratumorally either sequentially or in combination with pembrolizumab in patients with melanoma resistant to prior PD-1 blockade. Treatment was well tolerated. Objective responses were seen in 7 of 20 patients, and size reductions in noninjected lesions suggested local delivery of ONCOS-102 can drive a systemic anti-tumor effect. Serial biopsies of injected tumors at baseline, Week 3 (following ONCOS-102 and prior to pembrolizumab), and Week 9 (following ONCOS-102 and pembrolizumab) indicated that while most tumors experience CD8+ and CD4+ infiltration after ONCOS-102 injection, sustained infiltration at Week 9 was associated with clinical benefit. Future trials of ONCOS-102 and checkpoint inhibition are warranted in anti-PD-1-resistant melanoma. These findings suggest trials using viral agents in anti-PD-1-resistant disease should not solely rely on early onset of cytotoxicity to predict clinical response.Wainberg and colleagues report on the combination of very low doses of chemotherapy (10% of the usual dose) with a full dose of talazoparib (TAL). The study design reports preferentially increasing the dose of TAL before increasing the chemotherapy to improve the hematologic profile as well as exploring efficacy signals among non-BRCA patients. This phase I study demonstrates that TAL with low-dose temozolomide or irinotecan shows an improved hematologic toxicity profile than most prior chemo/PARP inhibitor combinations and has signals of clinical activity in small cell lung cancer and ovarian cancer. The results of this phase I study are supportive of ongoing trials with this combination.Obesity has been unexpectedly associated with improved outcomes with immune checkpoint inhibitors and BRAF-targeted therapies in metastatic melanoma; however, the biology underlying this observation is unknown. Hahn and colleagues examined associations between body mass index (BMI) and molecular, immune, and metabolic features of melanoma tumors as well as host microbiome in 782 patient specimens. Host BMI was associated with altered tumor metabolism, with downregulation of oxidative phosphorylation (OXPHOS) and other metabolic pathways in tumors from high BMI patients. OXPHOS has been associated with resistance to targeted and immune therapies, suggesting a potential mechanism underlying the “obesity paradox” in metastatic melanoma.Circulating tumor DNA (ctDNA) levels are associated with tumor volume and minimal residual disease in lymphoid malignancies. Fernández-Miranda and colleagues suggest that pre-treatment ctDNA levels in follicular lymphoma patients could be useful to predict response to treatment and early progression as an independent predictive biomarker or in combination with clinical variables. Circulating tumor DNA levels and cell-free DNA genotyping at mid-treatment and end-of-treatment are associated with treatment response and early progression follicular lymphoma. Circulating tumor DNA measurement at diagnosis and follow-up is a valuable tool that might feasibly be used in clinical trials and, eventually, in daily clinical practice.

Molecular Monitoring in Endometrial Cancer-Ready for Prime Time?

Efforts are under way to define the role of minimally invasive strategies for molecular monitoring and risk stratification in endometrial cancer. A recent publication aims to define the association between circulating tumor DNA level and disease stage in patients with newly diagnosed endometrial cancer and determine whether sequencing of longitudinal cell-free DNA samples can be used for disease monitoring and detection of progression or recurrence. These results accelerate the current knowledge of molecular follow-up in endometrial cancer. See related article by Ashley et al., p. 410.

Cell-Free HPV DNA Kinetics Predicted by Radiographic Response in Locoregional Viral-Associated Oropharyngeal Cancer Receiving Response-Adaptive Treatment – Exploratory Analysis of a Prospective Trial

<h3>Purpose/Objective(s)</h3> Human papillomavirus (HPV) associated oropharyngeal cancer (HPV+OPC) has a favorable prognosis. Current response-adapted strategies utilize RECIST to guide therapy. In the present study, we examined the utility of cell-free HPV DNA (cfHPV DNA) kinetic responses as an additional parameter to track therapy efficacy in de-escalation strategies. Here, we report a comparison of cfHPV DNA kinetics by RECIST and tumor volume (TV) from a prospective response-adaptive de-escalation trial. <h3>Materials/Methods</h3> Patients enrolled on the prospective phase II OPTIMA 2 (NCT03107182) de-escalation trial with available cfHPV DNA information were included for analysis. OPTIMA 2 enrolled locoregionally advanced HPV+OPC including low and high risk patients. High risk patients were defined as T4, N2c-N3 (AJCC 7^th edition), > 20 pack year smoking history, or non-HPV16 subtype. Neck CT or MRI as well as cfHPV DNA was obtained at baseline and following induction chemoimmunotherapy. Target lesions were assessed via RECIST 1.1 at baseline and post-induction therapy per protocol; patients with ≥ 50% response by RECIST received de-escalated radiation dose and volume. cfHPV DNA was detected and quantified using a CLIA-certified cfHPV sequencing assay (HPV-SEQ, Sysmex Inostics, Inc.). For this analysis, target lesions were delineated post hoc to obtain TV metrics. Linear regression was used to examine correlation between cfHPV DNA, RECIST, and TV response. Receiver Operating Characteristic (ROC) analysis was used to identify an optimal TV response to predict ≥ 95% cfHPV DNA response. <h3>Results</h3> 39 patients of which 31 had follow up cfHPV DNA information were evaluable. Median RECIST was 4.9 cm at baseline and 2.0 cm at follow up. Median TV was 29 cm³ at baseline and 6 cm³ at follow-up. 39 (100%) patients had detectable cfHPV DNA at baseline, with median 180 [IQR: 15, 966] copy number/mL. Of 31 patients with paired cfHPV DNA information at baseline, 29 (94%) had a ≥ 95% cfHPV DNA reduction. Of those, cfHPV DNA was undetectable in 21 (71%) cases. Baseline TV was associated with cfHPV DNA (p=0.04), and the median cfHPV DNA / TV ratio was 5.5 (copy number / cm³). No differences were observed between low and high-risk cohorts with respect to cfHPV DNA or radiographic metrics. RECIST was not associated with cfHPV DNA metrics. When adjusting for risk, TV response predicted cfHPV DNA response (p = 0.003). ROC analysis identified a TV response of 63% (AUC 0.88) to predict ≥ 95% cfHPV DNA response; 74% of patients had a TV response ≥ 63%. <h3>Conclusion</h3> cfHPV DNA kinetics were more pronounced than radiographic response to systemic therapy in both high and low risk groups. cfHPV DNA was predicted by TV response to chemoimmunotherapy, but was not predicted by traditional RECIST dynamics. We identified potential TV responses to predict cfHPV DNA response. This represents the first direct correlation of circulating tumor DNA levels to tumor volume and has implications for response assessment in the neoadjuvant setting as well as in other solid tumors.

Personalized neoantigen vaccine NEO-PV-01 with chemotherapy and anti-PD-1 as first-line treatment for non-squamous non-small cell lung cancer

Neoantigens arising from mutations in tumor DNA provide targets for immune-based therapy. Here, we report the clinical and immune data from a Phase Ib clinical trial of a personalized neoantigen-vaccine NEO-PV-01 in combination with pemetrexed, carboplatin, and pembrolizumab as first-line therapy for advanced non-squamous non-small cell lung cancer (NSCLC). This analysis of 38 patients treated with the regimen demonstrated no treatment-related serious adverse events. Multiple parameters including baseline tumor immune infiltration and on-treatment circulating tumor DNA levels were highly correlated with clinical response. De novo neoantigen-specific CD4+ and CD8+ Tcell responses were observed post-vaccination. Epitope spread to non-vaccinating neoantigens, including responses to KRAS G12C and G12V mutations, were detected post-vaccination. Neoantigen-specific CD4+ Tcells generated post-vaccination revealed effector and cytotoxic phenotypes with increased CD4+ Tcell infiltration in the post-vaccine tumor biopsy. Collectively, these data support the safety and immunogenicity of this regimen in advanced non-squamous NSCLC.

S216: CLINICAL ACTIVITY OF CC-99282, A CEREBLON E3 LIGASE MODULATOR (CELMOD) AGENT, IN PATIENTS (PTS) WITH RELAPSED/REFRACTORY NON-HODGKIN LYMPHOMA (R/R NHL) – RESULTS FROM A PHASE 1, OPEN-LABEL STUDY

Background: CC-99282 is a novel, oral small molecule CELMoD® agent that co-opts cereblon to induce targeted degradation of Ikaros/Aiolos, transcription factors critical for development of B-cell malignancies. Compared with immunomodulatory drugs (IMiD®) and other CELMoD agents, CC-99282 had similar immunostimulatory effects and 10- to 100-fold stronger antiproliferative and apoptotic activity in preclinical models of diffuse large B-cell lymphoma (DLBCL). Aims: To evaluate the safety, tolerability, maximum tolerated dose, pharmacokinetics (PK), and preliminary efficacy of CC-99282 in pts with R/R NHL. Methods: CC-99282-NHL-001 (NCT03930953) is a 2-part multicenter first-in-human study comprising dose escalation of CC-99282 monotherapy (part A) and expansion with or without combination partners (part B). Part A includes pts with R/R DLBCL or follicular lymphoma (FL) who had progressed after ≥2 lines of therapy, including IMiD/CELMoD agents and chimeric antigen receptor T-cell (CAR-T) therapy, and pts with R/R DLBCL who received ≥1 line of standard therapy and are unfit for transplant. Pts receive oral CC-99282 0.2, 0.4, 0.6, or 0.8 mg once daily on 3 intermittent dosing schedules of 28-day cycles, with ≥3 pts per dosing cohort. Results: As of Oct 6, 2021, 50 pts were treated in part A (38 DLBCL, 12 FL; median age 66y; 58% male); 17 pts (34%) were ongoing and 26 pts (52%) discontinued due to progressive disease. Grade 3/4 CC-99282–related adverse events were reported in 32 pts (64%); the most common were neutropenia (29 pts [58%]), thrombocytopenia (4 pts [8%]), and anemia (4 pts [8%]). Correlation analysis showed that grade 4 neutropenia in the first month was more strongly associated with number of prior lines of alkylating agent and anti-CD20 therapy than with CC-99282 dose level or schedule. Neutropenia was manageable with CC-99282 dose modifications and granulocyte colony–stimulating factors. All dose-limiting toxicities were hematologic. The maximal recommended doses for schedules of interest were 0.6 mg on 7/14 days and 0.4 mg on 14/28 days. For doses ≥0.4 mg on schedules of interest, the overall response rate was 42% (15/36 evaluable pts; 6 FL, 9 DLBCL), with complete responses in 6 pts and partial responses in 9 pts. Responders included pts previously treated with CAR-T therapy and/or IMiD/CELMoD agents. Responses were durable, with median durations of 239 days (range 48–587; median follow-up [mFUP] 247 days [range 21–690]) and 112 days (range 63–414; mFUP 121 days [range 22–464]) for 7/14- and 14/28-day schedules, respectively. CC-99282 was absorbed rapidly and had a prolonged terminal half-life (median ~50 hours at doses ≥0.4 mg), with considerable distribution into the peripheral compartment. Increase in plasma CC-99282 and degradation of Ikaros/Aiolos in peripheral T cells occurred in a dose-dependent manner, and maximum degradation (>90%) occurred by day 4 of treatment at doses ≥0.4 mg. Within 2 weeks of initiating CC-99282, peripheral T-cell subsets showed a significant shift toward a more activated phenotype (P<0.05). Analysis of mutant circulating tumor DNA levels showed rapid reductions that correlated with response to CC-99282, suggesting strong tumor cell–intrinsic activity. Summary/Conclusion: CC-99282 monotherapy showed a manageable safety profile and demonstrated promising efficacy in heavily pretreated pts with R/R NHL. PK and pharmacodynamic data were consistent with robust and rapid CC-99282 antitumor activity. This study is ongoing, with patients actively being enrolled in the monotherapy and CC-99282+rituximab combination expansion cohorts.