Citations

3040 Background: Pembrolizumab was recently FDA approved across solid tumors for TMB scores ≥ 10mut/Mb as assessed by next-generation sequencing (NGS) of tissue (tTMB). A prior study of advanced cancer patients treated with immunotherapy found that higher somatic TMB, as defined by the 80th percentile in each histology, was associated with better overall survival. Previously, bTMB assessed by ctDNA from patients with newly diagnosed advanced NSCLC at a score of 16 mut/MB correlated with a tTMB score of 10 mut/MB. TMB levels vary by cancer type, line of treatment, and therapy received; the distribution of bTMB scores across solid tumor types has not been well characterized. Here we report the distribution of bTMB scores in patients with advanced malignancies. Methods: We queried 5,610 samples from patients with different cancer types undergoing clinical cell-free DNA testing (Guardant360; Redwood City, CA) and assessed bTMB scores from October 2020 - January 2021. bTMB score was derived via a previously described computational algorithm examining the total number of synonymous and non-synonymous SNVs and indels across a 1.0MB genomic footprint. We assessed the success rate of bTMB evaluation, overlap with microsatellite instability (MSI) status, and defined the distribution of bTMB levels across indications in this dataset. Results: bTMB score was successfully assessed in 4,275/5,610 (76.3%) samples (Table). The majority of samples (58%) were tested at disease progression as compared to initial diagnosis (42%). The median turnaround time from sample receipt to clinical reporting was 11 days and decreased to 9 days over the course of the study. For the majority of cancer types the 80th percentile TMB was ≥ 16 mut/MB tissue equivalency. Conclusions: Our analysis demonstrates the feasibility of measuring bTMB using a commercially available liquid biopsy assay. bTMB scores trended higher than tTMB previously reported in these cancer types, reflecting the ability of ctDNA to better capture tumor heterogeneity. cfDNA may allow for exploration of bTMB evolution throughout treatment. TMB should be interpreted in the context of disease, treatment, and method; these data establish a pan-cancer benchmark for bTMB which will serve as a resource for further studies.[Table: see text]

256 Background: PARP inhibitors, olaparib and rucaparib recently improved survival outcomes (in the Profound and Triton-2 trials) in pts with aPC harboring HRRm. Notably, ~35% of pts screened for the PROfound trial did not meet eligibility solely due to the lack of adequate quality/quantity of tumor tissue required for CGP (De Bono, NEJM, 2020). cfDNA analysis non-invasively assesses tumor-derived genomic alterations. We evaluated the prevalence of HRRm in a real-world aPC population, who had commercially available cfDNA assay results available. Methods: cfDNA based CGP (using a clinically-validated 73- to 74-gene panel i.e. Guardant360 or G360) from consecutive aPC pts between 11/2016–8/2020 were used for detection of HRRm. Frameshift and nonsense mutations were included as pathogenic. Variants of unknown significance were excluded. In this unmatched study, the prevalence of each HRRm was compared with those reported in literature using the chi square test. Results: cfDNA CGP from 7701 aPC pts were available for interrogation of BRCA1/BRCA2 mutations, & from 4671 aPC pts for ATM mutations. Prevalence of BRCA1 and 2 as detected by cfDNA was similar to historical CGP of primary tissue. Prevalence of BRCA1 was higher than historical CGP of metastatic tissue. Prevalence of ATM in cfDNA was higher than historic tumor tissue CGP but similar to prior reports from cfDNA testing (Table). Conclusions: In this large real-world population of pts with aPC undergoing routine cfDNA CGP by a CLIA certified lab, prevalence of HRRm was similar (or higher for BRCA1 and ATM) to what has been previously reported from the tumor tissue. These data provide the rationale for utilizing cfDNA CGP as a routine test for detection of HRRm in men with aPC to identify men who are candidates for PARPi. [Table: see text]

LBA110 Background: There are limited data on COVID-19 in patients with cancer. We characterize the outcomes of patients with cancer and COVID-19 and identify potential prognostic factors. Methods: The COVID-19 and Cancer Consortium (CCC19) cohort study includes patients with active or prior hematologic or invasive solid malignancies reported across academic and community sites. Results: We included 1,018 cases accrued March-April 2020. Median age was 66 years (range, 18-90). Breast (20%) and prostate (16%) cancers were most prevalent; 43% of patients were on active anti-cancer treatment. At time of data analysis, 106 patients (10.4%) have died and 26% met the composite outcome of death, severe illness requiring hospitalization, and/or mechanical ventilation. In multivariable logistic regression analysis, independent factors associated with increased 30-day mortality were age, male sex, former smoking, ECOG performance status (2 versus 0/1: partially adjusted odds ratio (pAOR) 2.74, 95% CI 1.31-5.7; 3/4 versus 0/1: pAOR 5.34, 95% CI 2.44-11.69), active malignancy (stable/responding, pAOR 1.93, 95% CI 1.06-3.5; progressing, pAOR 3.79, 95% CI 1.78-8.08), and receipt of azithromycin and hydroxychloroquine. Tumor type, race/ethnicity, obesity, number of comorbidities, recent surgery, and type of active cancer therapy were not significant factors for mortality. Conclusions: All-cause 30-day mortality and severe illness in this cohort were significantly higher than previously reported for the general population and were associated with general risk factors as well as those unique to patients with cancer. Cancer type and treatment were not independently associated with increased 30-day mortality. Longer follow-up is needed to better understand the impact of COVID-19 on outcomes in patients with cancer, including the ability to continue specific cancer treatments.

5061 Background: The phase 3 JAVELIN Renal 101 trial (NCT02684006) in treatment-naive patients with advanced renal cell carcinoma (aRCC) demonstrated significantly improved progression-free survival (PFS; hazard ratio [HR], 0.69; 95% CI, 0.56, 0.84; P < 0.001) and higher objective response rate (ORR; 51.4% vs 25.7%) with avelumab + axitinib vs sunitinib (Motzer RJ, et al. N Engl J Med. 2019;380:1103-15). NLR has emerged as a potential prognostic biomarker in aRCC; elevated NLR is associated with poorer prognosis. Here, we describe the association of NLR with the efficacy of avelumab + axitinib from JAVELIN Renal 101. Methods: We examined baseline NLR and its association with efficacy outcomes. PFS, best overall response (per blinded independent central review using RECIST 1.1), and overall survival (OS) data from the avelumab + axitinib arm from the first interim analysis of JAVELIN Renal 101 were analyzed (data cutoff, June 20, 2018). Multivariate Cox regression analyses of PFS and OS were also conducted. Results: In the avelumab + axitinib arm, patients with < median NLR (N = 217) had longer observed PFS (stratified HR, 0.85; 95% CI, 0.634, 1.153) and longer observed OS (stratified HR, 0.51; 95% CI, 0.300, 0.871) than patients with ≥ median NLR (N = 217). The ORR was 57.1% in patients with < median NLR vs 47.5% in patients with ≥ median NLR, with complete response in 5.5% vs 1.4%. Multivariate analysis showed that low NLR was associated with longer PFS and OS by treating baseline NLR as either a continuous variable or a binary variable (dichotomized by median). Conclusions: Low NLR was associated with better observed treatment outcomes in patients with aRCC who received avelumab + axitinib. Clinical trial information: NCT02684006 .

Abstract Background The ability to accurately monitor response to treatment in patients with metastatic castration resistant prostate cancer (mCRPC) on chemotherapy has been a challenge. Conventional methods of therapy response assessment have limitations and molecular imaging has been explored as an important alternative. We set out t o determine if anti-1-amino-3-anti-1-amino-3-[18F]-fluorocyclobutane-1-carboxylic acid ([18F]fluciclovine) positron emission tomography/computed tomography (PET/CT) changes reflect response to docetaxel chemotherapy in mCRPC. Results Seven patients with mCRPC were enrolled. Each patient was scheduled to have [18F]fluciclovine PET/CT at baseline, and after 1 and 6 cycles of chemotherapy. Uptake parameters were recorded in the prostate/bed and up to 10 metastatic lesions. Decrease in uptake of ≥30% was considered response (R); appearance of new lesions or >30% increase in uptake was progressive disease (PD); and change of < 30% uptake was stable disease (SD). Prostate specific antigen (PSA) was obtained at baseline and before each cycle. Bone scintigraphy and CT were acquired at baseline and after the 6th cycle. Assessment of response was based on Prostate Cancer Clinical Trial Working Group 3 recommendations. Correlation between [18F]fluciclovine uptake and time to PSA progression was also determined. All patients completed the 1 st and 2 nd [18F]fluciclovine PET/CT, while 4/7 patients completed all 3 scans. PET response correlated with PSA response in 3/7 (42.9%) patients and 3/4 (75%) patients after 1 and 6 cycles of docetaxel, respectively. Bone scan and CT correlated with PSA response in 1/4 (25%) patients. Mean SUVmax and SUVmean were significantly higher in patients with progressive disease versus non-progressive disease after 6 cycles of docetaxel (p<0.05), but not at baseline or after 1 cycle of docetaxel. There was non-significant correlation of changes in [18F]fluciclovine uptake with changes in PSA after 1 and 6 cycles of docetaxel. There was no significant correlation between PET parameters and time to PSA progression. Conclusion [18F]fluciclovine PET/CT has better correlation than CT or bone scan with PSA response for patients with mCRPC treated with docetaxel. [18F]fluciclovine PET/CT did not predict time to PSA progression. Larger studies exploring the utility of [18F]fluciclovine PET for response assessment are recommended.

26 Background: NKTR-262 is a novel intratumoral prodrug designed to promote tumor antigen release, an immune stimulatory environment, and antigen presentation. NKTR-214 increases CD8+ T cells and NK cells in the tumor microenvironment. The combination of NKTR-262 with NKTR-214 accesses innate and adaptive immunity to provide an abscopal response and systemic tumor immunity. The Phase 1b/2 REVEAL trial is enrolling. Methods: In a 3+3 Phase 1 design, pts who are relapsed/refractory to ≥1 CPI receive escalating doses of intratumoral (IT) NKTR-262 followed by combined q3w treatment of IT NKTR-262 and fixed-dose intravenous (IV) NKTR-214 (0.006 mg/kg). Phase 1 will evaluate PK, safety, efficacy, and determine recommended Phase 2 dose. Scans are conducted every 9 wks (± 1 wk). Peripheral blood (PB) and tumor tissue are collected to measure biomarkers of immune activation. In Phase 2 expansion, NKTR-262 + NKTR-214 ± IV nivolumab (360 mg) will be assessed in specific tumor cohorts of IO-naïve and experienced pts. Results: As of 06 Nov 2018, 11 pts had received at least one cycle of NKTR-262 + NKTR-214 therapy. 7/11 pts were efficacy evaluable with at least one on-treatment scan (4 MEL, 2 SARC, 1 CRC). 2/4 R/R melanoma pts had uPRs with 100% (scan 2) and 40% (scan 1) reductions in target lesions per RECIST 1.1, respectively. Both patients remain on treatment. Two SARC pts had stable disease at scan 1. No pts experienced G3 or higher TRAEs or immune-related adverse events (AEs). Most common G1-2 AEs were transient flu-like symptoms. Gene expression analysis of tumor and PB show dose-dependent induction (4 to 16-fold) of TLR target genes. Consistent with the mechanism of action for NKTR-214, PB flow cytometry shows an average 13-fold increase from baseline in Ki67+ CD8+T cells in 6 pts. Conclusions: NKTR-262 + NKTR-214 engage the immune activation cascade from local tumor antigen production to anti-tumor T cell response. Initial dose levels of NKTR-262 with fixed-dose NKTR-214 were well-tolerated with early evidence of clinical activity. These data support continued evaluation of the combination +/- nivolumab. Clinical trial information: NCT03435640.