Shao, Spencer H.

Background Standard first-line therapies for metastatic colorectal cancer (mCRC) include fluoropyrimidine-containing regimens with oxaliplatin and/or irinotecan and a biologic agent. Immunotherapy may enhance antitumor activity in combination with standard therapies in patients with mCRC. Here, we present phase 2 results of nivolumab plus standard-of-care therapy (SOC; 5-fluorouracil/leucovorin/oxaliplatin/bevacizumab) versus SOC in the first-line treatment of patients with mCRC (CheckMate 9X8). Methods CheckMate 9X8 was a multicenter, open-label, randomized, phase 2/3 trial. Eligible patients were at least 18 years of age with unresectable mCRC and no prior chemotherapy for metastatic disease. Patients were randomized 2:1 to receive nivolumab 240 mg plus SOC or SOC alone every 2 weeks. The primary endpoint was progression-free survival (PFS) by blinded independent central review (BICR) per Response Evaluation Criteria in Solid Tumors V.1.1. Secondary endpoints included PFS by investigator assessment; objective response rate (ORR), disease control rate, duration of response, and time to response, all by BICR and investigator assessments; overall survival; and safety. Preplanned exploratory biomarker analyses were also performed. Results From February 2018 through April 2019, 310 patients were enrolled, of which 195 patients were randomized to nivolumab plus SOC (n=127) or SOC (n=68). At 21.5-month minimum follow-up, PFS with nivolumab plus SOC versus SOC did not meet the prespecified threshold for statistical significance; median PFS by BICR was 11.9 months in both arms (HR, 0.81 (95% CI, 0.53 to 1.23); p=0.30). Higher PFS rates after 12 months (18 months: 28% vs 9%), higher ORR (60% vs 46%), and durable responses (median 12.9 vs 9.3 months) were observed with nivolumab plus SOC versus SOC. Grade 3–4 treatment-related adverse events were reported in 75% versus 48% of patients; no new safety signals were identified. Conclusions The CheckMate 9X8 trial investigating first-line nivolumab plus SOC versus SOC in patients with mCRC did not meet its primary endpoint of PFS by BICR. Nivolumab plus SOC showed numerically higher PFS rates after 12 months, a higher response rate, and more durable responses compared with SOC alone, with acceptable safety. Further investigation to identify subgroups of patients with mCRC that may benefit from nivolumab plus SOC versus SOC in the first-line setting is warranted. Trial registration number NCT03414983 .

There are four solid tumors with common screening options in the average-risk population aged 21 to 75 years (breast, cervical, colorectal, and, based on personalized risk assessment, prostate), but many cancers lack recommended population screening and are often detected at advanced stages when mortality is high. Blood-based multi-cancer early detection tests have the potential to improve cancer mortality through additional population screening. Reported here is a post-hoc analysis from the third Circulating Cell-free Genome Atlas substudy to examine multi-cancer early detection test performance in solid tumors with and without population screening recommendations and in hematologic malignancies. Participants with cancer in the third Circulating Cell-free Genome Atlas substudy analysis were split into three subgroups: solid screened tumors (breast, cervical, colorectal, prostate), solid unscreened tumors, and hematologic malignancies. In this post hoc analysis, sensitivity is reported for each subgroup across all ages and those aged ⩾50 years overall, by cancer, and by clinical cancer stage. Aggregate sensitivity in the solid screened, solid unscreened, and hematologic malignancy subgroups was 34%, 66%, and 55% across all cancer stages, respectively; restricting to participants aged ⩾50 years showed similar aggregate sensitivity. Aggregate sensitivity was 27%, 53%, and 60% across stages I to III, respectively. Within the solid unscreened subgroup, aggregate sensitivity was >75% in 8/18 cancers (44%) and >50% in 13/18 (72%). This multi-cancer early detection test detected cancer signals at high (>75%) sensitivity for multiple cancers without existing population screening recommendations, suggesting its potential to complement recommended screening programs. Clinical trial identifier: NCT02889978.

8 Background: Standard 1L therapies for mCRC include a fluoropyrimidine with oxaliplatin and/or irinotecan, and a biologic agent. NIVO may enhance antitumor activity in combination with 1L standard therapies within a subset of patients (pts) with mCRC. CheckMate 9X8 evaluated NIVO + mFOLFOX6/BEV vs mFOLFOX6/BEV in 1L mCRC (NCT03414983). Methods: Adults with previously untreated, unresectable, mCRC were randomized 2:1 to NIVO 240 mg + mFOLFOX6/BEV Q2W (NIVO + standard-of-care [SOC]) or mFOLFOX6/BEV Q2W (SOC). Primary endpoint was progression-free survival (PFS) assessed by blinded independent central review (BICR) per RECIST v1.1. Key secondary endpoints included objective response rate (ORR), disease control rate (DCR), time to response (TTR), duration of response (DOR), overall survival (OS), and safety. Results: 195 pts were randomized to NIVO + SOC (n = 127) or SOC (n = 68). Median (range) follow-up was 23.7 (0–33.2) months (mo; NIVO + SOC) vs 23.2 (0–32.3) mo (SOC). Median (range) duration of therapy was 9.9 (0.1–31.8+) mo (NIVO + SOC) and 7.7 (0.1–26.7+) mo (SOC). The HR (95% CI) for PFS was 0.81 (0.53–1.23; P = 0.30), which did not meet the prespecified threshold for statistical significance (median PFS, 11.9 mo in both arms; Table). PFS rates after 12 mo were higher with NIVO + SOC vs SOC (Table). ORR was 60% (NIVO + SOC) and 46% (SOC; odds ratio 1.72 [95% CI 0.96–3.10]) and median (95% CI) DOR was 12.9 (9.0–13.1) mo (NIVO + SOC) and 9.3 (7.5–11.3) mo (SOC; Table). Rates of grade 3−4 treatment-related adverse events (TRAEs) were higher with NIVO + SOC; however, no new safety signals were identified (Table). Biomarker analyses, including tumor mutational burden and baseline CD8 levels, will be presented. Conclusions: The primary endpoint of PFS was not met; however, NIVO + SOC showed higher PFS rates after 12 mo, a higher response rate, and more durable responses compared with SOC, along with acceptable safety, in 1L mCRC. Clinical trial information: NCT03414983. [Table: see text]

3072 Background: The Circulating Cell-free Genome Atlas study (CCGA; NCT02889978) previously demonstrated that a blood-based multi-cancer early detection (MCED) test utilizing cell-free DNA (cfDNA) sequencing in combination with machine learning could detect cancer signals across multiple cancer types and predict cancer signal origin. Cancer classes were defined within the CCGA study for sensitivity reporting. Separately, cancer types defined by the American Joint Committee on Cancer (AJCC) criteria, which outline unique staging requirements and reflect a distinct combination of anatomic site, histology and other biologic features, were assigned to each cancer participant using the same source data for primary site of origin and histologic type. Here, we report CCGA ‘cancer class’ designation and AJCC ‘cancer type’ assignment within the third and final CCGA3 validation substudy to better characterize the diversity of tumors across which a cancer signal could be detected with the MCED test that is nearing clinical availability. Methods: CCGA is a prospective, multicenter, case-control, observational study with longitudinal follow-up (overall population N = 15,254). Plasma cfDNA from evaluable samples was analyzed using a targeted methylation bisulfite sequencing assay and a machine learning approach, and test performance, including sensitivity, was assessed. For sensitivity reporting, CCGA cancer classes were assigned to cancer participants using a combination of the type of primary cancer reported by the site and tumor characteristics abstracted from the site pathology reports by GRAIL pathologists. Each cancer participant also was separately assigned an AJCC cancer type based on the same source data using AJCC staging manual (8th edition) classifications. Results: A total of 4077 participants comprised the independent validation set with confirmed status (cancer: n = 2823; non-cancer: n = 1254 with non-cancer status confirmed at year-one follow-up). Sensitivity was reported for 24 cancer classes (sample sizes ranged from 10 to 524 participants), as well as an “other” cancer class (59 participants). According to AJCC classification, the MCED test was found to detect cancer signals across 50+ AJCC cancer types, including some types not present in the training set; some cancer types had limited representation. Conclusions: This MCED test that is nearing clinical availability and was evaluated in the third CCGA substudy detected cancer signals across 50+ AJCC cancer types. Reporting CCGA cancer classes and AJCC cancer types demonstrates the ability of the MCED test to detect cancer signals across a set of diverse cancer types representing a wide range of biologic characteristics, including cancer types that the classifier has not been trained on, and supports its use on a population-wide scale. Clinical trial information: NCT02889978.

3071 Background: Disparities in cancer screening and outcomes based on factors such as gender, socioeconomic status, and race/ethnicity are well documented.1 The Circulating Cell-free Genome Atlas study (CCGA; NCT02889978) was designed to develop and validate a blood-based multi-cancer early detection (MCED) test analyzing plasma cell-free DNA (cfDNA) to detect cancer signals across multiple cancer types and simultaneously predict cancer signal origin. Findings stratified by race/ethnicity from the third and final CCGA validation sub-study are reported. Methods: CCGA is a prospective, multicenter, case-control, observational study with longitudinal follow-up (overall N = 15,254). In this pre-specified exploratory analysis from the third substudy, key objectives were to evaluate test performance for cancer signal detection (specificity, overall sensitivity, and sensitivity by clinical stage) among racial/ethnic groups. Plasma cfDNA from evaluable samples was analyzed using a targeted methylation bisulfite sequencing assay and a machine learning approach. Overall, 4077 participants comprised the independent validation set with confirmed status (cancer: n = 2823; non-cancer: n = 1254). The groups stratified by race/ethnicity were White Non-Hispanic, Black Non-Hispanic, Other Non-Hispanic (including but not limited to Asian, Native Hawaiian, Pacific Islander, American Indian, Alaska Native), Hispanic (all races), and Other/unknown. The study was not powered to detect statistical differences between groups. Results: Cancer and non-cancer groups were predominantly White (2316/2823, 82.0% and 996/1254, 79.4%, respectively). Across racial/ethnic groups, specificity for cancer signal detection was 99.6% (White Non-Hispanic: 992/996, 95% confidence interval [99.0-99.8%]), 100.0% (Black Non-Hispanic: 85/85 [95.7-100.0%]), 100.0% (Other Non-Hispanic: 33/33 [89.6-100.0%]), 98.1% (Hispanic: 101/103 [93.2-99.5%]), and 100% (Other/unknown: 37/37 [90.6-100.0%]). Despite slight differences in cancer type and staging across racial/ethnic groups, overall sensitivity for cancer signal detection among groups ranged from 43.9% to 63.0% (White Non-Hispanic: 50.5%, 1169/2316 [48.4-52.5%], Black Non-Hispanic: 53.9%, 104/193 [46.8-60.8%], Other Non-Hispanic: 43.9%, 25/57 [31.8-56.7%], Hispanic: 63.0%, 121/192 [56.0-69.5%], and Other/unknown: 52.3%, 34/65 [40.4-64.0%]). For all racial/ethnic groups, sensitivity generally increased with clinical stage (with limited exceptions at Stage IV in some groups with small sample sizes). Conclusions: The MCED test demonstrated consistent specificity and sensitivity across racial/ethnic groups, though results are limited by sample size for some groups. These findings indicate broad applicability and support clinical implementation of this MCED test on a population scale. 1. Zavela et al. Brit J Cancer 2021. Clinical trial information: NCT02889978.

677 Background: Napabucasin a first-in-class cancer stemness inhibitor in clinical development, suppresses cancer stemness by targeting Stat3-driven gene transcription. Preclinically, potent and broad-spectrum anti-cancer activity was observed in vitro and in vivo, alone and in combination with other agents. In a phase 1 study, napabucasin monotherapy was well tolerated with encouraging signs of anti-tumor activity at the RP2D of 500 mg BID. Methods: The current open-label, multi-center study includes phase II expansion in pts with refractory, K- Raswt mCRC to confirm safety and anti-tumor activity of napabucasin administered orally at 480mg BID in combination with panitumumab (6mg/kg bi-weekly). Results: 72 pts were enrolled, 48 pts were evaluable by RECIST of which 7 (15%) and 41 (85%) had 2 or >3 prior treatment lines, respectively. Of the 48 evaluable pts, 64.6% (31/48) were previously treated with an anti-EGFR agent. No new adverse events (AEs) were observed and most common AEs included grade 1/2 diarrhea, nausea, abdominal cramps, and vomiting. Among 48 pts enrolled who received RECIST evaluation, Disease Control Rate (DCR) was observed in 25 pts (52.1%) of which 3 pts achieved PR (6%) and 22 pts achieved SD (45%). Among 31 pts previously treated with anti-EGFR therapy, DCR was observed in 15 pts (48%) compared with DCR of 59% observed in 10 out of 17 anti-EGFR naïve pts receiving a scan. Conclusions: This phase II study confirmed that napabucasin can be safely combined with panitumumab at full dose and shows encouraging anti-tumor activity in pts with K- Ras wt mCRC, regardless of prior anti-EGFR exposure, suggesting that napabucasin may sensitize pts to repeat anti-EGFR therapy. Clinical trial information: NCT01776307. [Table: see text]

370 Background: The Phase 1 portion of a Phase 1/2 trial of Necuparanib (“Necu”) combined with nab-paclitaxel (nabP) + gemcitabine (gem) in patients with metastatic pancreatic cancer (ClinicalTrials.gov Identifier NCT01621243) showed acceptable safety and tolerability and encouraging signals of activity and established a dose for the randomized, placebo (PBO)-controlled Phase 2 portion. Methods: In Phase 2, patients received daily s.c. injections of either 5 mg/kg Necu daily or PBO, combined with i.v. 125 mg/m2 nabP and 1000 mg/m2 gem (Days 1, 8, 15 of each 28-day cycle). The primary endpoint was overall survival (OS); other endpoints included progression-free survival (PFS), response rates, safety, and CA19.9 levels. An interim futility analysis was conducted in July 2016 once 57 deaths (50% of the target number of 114 events required for trial completion) had occurred. Results: The analysis was conducted on data from 120 randomized patients (62 Necu, 58 PBO). The Z-score for futility was -0.42 (prespecified boundary of -0.148 was crossed as actual score was lower). Median OS was Necu = 10.71 and PBO = 9.99 months; hazard ratio (HR) = 1.12 (favoring PBO); OS curves were intertwined. PFS was Necu = 5.52 and PBO = 6.93 months; HR = 0.97. RECIST response rates were comparable between arms: complete response, Necu = 0%, PBO = 3%; partial response, Necu = 26%, PBO = 26%; stable disease, Necu = 31%, PBO = 34%; disease control rate, Necu = 56%, PBO = 64%. The most common Grade 3+ adverse events (AEs) were neutropenia (Necu = 33%, PBO = 33%), thrombocytopenia (Necu = 27%, PBO = 5%), and anemia (Necu = 22%, PBO = 11%). There were lower rate of serious AEs with Necu (48%) vs. PBO (60%). Modest increases in APTT, AST, and ALT were noted following Necu relative to PBO. 23% of Necu and 5% of PBO patients were IgG positive with an anti-heparin/PF4 antibody titer of ≥ 0.4 at any time. There were no treatment differences for decreases in CA19.9. Conclusions: No new safety signals were observed and the toxicity profile was considered manageable; however, Necu in combination with nabP and gem did not show a sufficient level of efficacy in metastatic pancreatic cancer to warrant continued enrollment. Clinical trial information: NCT01621243.