Citations

e15599 Background: Screening and removal of pre-malignant adenomas has reduced CRC incidence in adults older than 50 years (later onset CRC [LOCRC]), but EOCRC incidence has increased by 1-2% annually since the 1990s. The liver is the commonest site of CRC metastasis, and EOCRC presents with more advanced stage compared with LOCRC. Oligometastasis (OM) refers to potentially resectable CRC, and complete resection of CRC primary and OM is associated with improved survival and potential cure. Here, we examined treatment outcomes of EOCRC with synchronous liver oligometastases (sLiOM) at our institution. Methods: We performed a retrospective review of institutional electronic health records and identified 160 EOCRC patients with sLiOM treated with curative intent in the last decade. Demographics, treatment, and follow up data were recorded, and analysis for survival outcomes performed. The study protocol was exempt after review by Mayo Clinic institutional review board. Results: Of 160 patients, median age at diagnosis was 43 years. Primary tumor was in the left colorectum in 73% and right colon in 26% of patients. Metastasis was limited to the liver only in 64%, and liver metastasis was solitary in 14% of patients (table 1). Fluoropyrimidine doublet backbone (81%) was more commonly used compared to triplet (19%), with doublet + bevacizumab (41%) as the most common regimen. Hepatectomy only (59%), combined hepatectomy with ablation (32%), ablation only (5%), transarterial radioembolization (2%), and trans arterial embolization (1%) were the modalities employed for sLiOM. Of the 148 patients who underwent hepatectomy, R0 resection was achieved in 51%. After a median follow-up of 37 months, progression-free survival was 11.6 mos (95% CI 9-14mos) and median overall was 83.6 mos (95% CI 62-105mos). The median time to liver progression was 16 mos (95% CI 12-20 mos). At data cut off, 41 patients (26%) were alive and disease-free, and 60 patients (38%) were alive and disease free in the liver only. Conclusions: This multi-site, retrospective analysis of EOCRC patients demonstrates excellent survival outcomes with localized treatment of sLiOM. Median OS in this cohort compares favorably to previously reported mOS of 36 months in EOCRC patients (Arhin et al, 2021). Cure is not often achieved even after treatment of sLiOM in this cohort, suggesting aggressive disease biology and the need for improved patient selection. [Table: see text]

TPS3641 Background: Patients with mismatch repair proficient (pMMR) BRAF V600E mutant high-risk stage II (T4) or stage III colon cancer have a substantial risk of recurrence despite standard adjuvant therapy. In patients with metastatic BRAF V600E mutant colorectal cancer, the combination of the RAF inhibitor encorafenib and the EGFR inhibitor cetuximab has been shown to improve overall and progression-free survival compared to standard therapy after at least one prior line of therapy. This study will evaluate if this combination improves disease-free survival (DFS) in patients with resected BRAF V600E mutant pMMR/microsatellite stable (MSS) high-risk stage II (T4) or stage III colon cancer after standard adjuvant therapy. Methods: The study has a seamless phase II/III design, enrolling a maximum of 394 patients. BRAF mutation status can be determined locally or submitted for central testing in trial pre-screening. Eligible patients will be randomized 1:1 to usual surveillance versus 6 months of treatment with encorafenib (300mg oral daily) plus cetuximab (500mg/m2 intravenous every 14 days). Stratification factors are adjuvant chemotherapy regimen (FOLFOX versus CAPOX), duration of adjuvant therapy (3 months versus > 3 months), tumor stage (T4N0 versus T1-3N1 versus T4N1/TanyN2), and ctDNA marker status (detectable versus undetectable) at randomization. Adjuvant therapy must be completed at most 8 weeks prior to registration. For the phase II component, in the ctDNA detectable cohort, the primary endpoint will be ctDNA clearance rate at 6 months, and, in the ctDNA undetectable cohort, the primary endpoint will be 6-month ctDNA recurrence-free survival, where events consist of death, recurrence, or ctDNA positivity. The primary endpoint of the phase III component is DFS, and secondary endpoints are overall survival, adverse events, and alternative DFS calculated from the date of primary resection, rather than date of study randomization. Patient reported symptoms (PRO-CTCAE) will be collected and analyzed as an exploratory endpoint, and serial blood banking will support future correlative studies. The trial will proceed to the phase III portion if either of the two endpoints in the phase II cohorts is statistically superior in patients receiving encorafenib plus cetuximab. The phase III study sample size will provide 80% power at a one-sided α of 0.05 to detect an approximately 10% improvement in the three-year DFS rate, assuming 68% in the control arm. Two interim analyses will be performed for DFS endpoint. Support: U10CA180821, U10CA180882; https://acknowledgments.alliancefound.org . U10CA180820 (ECOG-ACRIN); U10CA180868 (NRG); U10CA180888 (SWOG); Pfizer, Eli Lilly; Clinicaltrials.gov ID: NCT05710406. Clinical trial information: NCT05710406 .

TPS3640 Background: Recent data have demonstrated that in locally advanced rectal cancer (LARC), a total neoadjuvant therapy (TNT) approach improves compliance with chemotherapy and increases rates of tumor response compared to neoadjuvant chemoradiation (CRT) alone. They further indicate that the optimal sequencing of TNT involves consolidation (rather than induction) chemotherapy to optimize complete response rates. Data, largely from retrospective studies, have also shown that patients (pts) with clinical complete response (cCR) after neoadjuvant therapy may be managed safely with the watch and wait approach (WW) instead of preemptive total mesorectal resection (TME). However, the optimal consolidation chemotherapy regimen to achieve cCR has not been established, and a randomized clinical trial has not robustly evaluated it as a primary endpoint. Collaborating with a multidisciplinary oncology team and pt groups, we designed this NCI-sponsored study of chemotherapy intensification to address these issues and to drive up cCR rates, to provide opportunity for organ preservation and improve quality of life for pts. Methods: In this Alliance for Clinical Trials in Oncology randomized phase II trial (1:1), up to 312 pts with microsatellite stable LARC, clinical stage T4N0, any T, N+ or T3N0 requiring abdominoperineal resection or coloanal anastomosis and distal margin within 12 cm of anal verge will be enrolled. Stratification factors include tumor stage (T4 vs T1-3), nodal stage (N+ vs N0) and distance from anal verge (0-4; 4-8; 8-12 cm). Pts will be randomized to receive neoadjuvant long course CRT (LCRT) followed by consolidation doublet (mFOLFOX6 or CAPOX) or triplet chemotherapy (mFOLFIRINOX) for 4 months. LCRT in both arms involves 4500 cGy in 25 fractions over 5 weeks (w) + 900 cGy boost in 5 fractions with a fluoropyrimidine (capecitabine preferred). Pts will undergo assessment 8-12 w post-TNT completion for the primary endpoint of cCR per previously validated criteria and recommended WW and surveillance if cCR is achieved or TME if an incomplete response is noted. Secondary objectives include time-to event outcomes (disease-free and overall survival, organ preservation time and time to distant metastasis) and adverse effects. Statistical power, based on cCR, incorporates a one-sided alpha = 0.048 and power = 90% yielding 312 patients (156 per arm). Biospecimens including archival tumor tissue, matched / normal blood samples and serial rectal MRI will be collected for exploratory correlative research. This study, activated in late 2022, is open across the NCTN and is actively recruiting. Support: U10CA180821, U10CA180882, U24 CA196171; https://acknowledgments.alliancefound.org . U10CA180868 (NRG); U10CA180888 (SWOG); Clinicaltrials.gov ID: NCT05610163 Clinical trial information: NCT05610163 .

TPS3629 Background: For patients with oligometastatic colorectal cancer (CRC), aggressive local therapy of isolated metastases, particularly in the liver, has been associated with long-term progression-free survival and overall survival (OS) primarily based on retrospective evidence. However, in patients with limited metastatic CRC that is deemed inoperable or those with additional disease outside of the liver or lungs, the role of local ablative therapies, including microwave ablation (MWA) and stereotactic body radiation therapy (SBRT), to render patients disease free is less clear. Further, despite the long history of treating oligometastatic CRC with local therapy, which is provider biased and not evidence based, questions remain regarding the benefit of extending the paradigm of metastatic directed therapy to patients with more extensive disease. This trial seeks to use a pragmatic multimodality approach that mirrors the current clinical dilemma. This study is designed to evaluate the safety and efficacy of adding total ablative therapy (TAT) of all sites of disease to standard of care systemic treatment in those with limited metastatic CRC. Methods: A022101 is a National Clinical Trials Network randomized phase III study planned to enroll 364 patients with newly diagnosed metastatic CRC (BRAF wild-type, microsatellite stable) with ≤4 sites of metastatic disease on baseline imaging. Liver-only metastatic disease is not permitted, and lesions must be amenable to any combination of surgical resection, MWA, and/or SBRT with SBRT required for at least one lesion. Patients receive first-line systemic therapy for 4-6 months and are then randomized 1:1, stratified by number of metastatic organ sites (1-2 vs. 3-4), timing of metastatic disease diagnosis (de novo vs. secondary), and presence of metastatic disease outside the liver and lungs in at least one site. Patients in Arm 1 will receive TAT which consists of treatment of all metastatic sites with SBRT ± MWA ± surgical resection followed by standard of care systemic therapy. Patients in Arm 2 will continue with standard of care systemic therapy alone. The primary endpoint is OS. Secondary endpoints include event-free survival, treatment-related toxicities, and local recurrence with exploratory biomarker analyses. The study needs 346 evaluable patients combined in the 2 arms to demonstrate an improvement in OS with a hazard ratio of 0.7 to provide 80% power with a one-sided alpha of 5%. The trial utilizes a group sequential design with two interim analyses (25% and 50% of events) for futility. The trial activated in January 2023 and recruitment is ongoing. Support: U10CA180821, U10CA180882; https://acknowledgments.alliancefound.org. U10CA180820 (ECOG-ACRIN); U10CA180868 (NRG); U10CA180888 (SWOG); Clinicaltrials.gov identifier: NCT05673148 Clinical trial information: NCT05673148 .

TPS3628 Background: Colorectal cancer (CRC) is the third most frequently diagnosed cancer and the second leading cause of cancer-related mortality worldwide. PD-1/PD-L1 inhibition, in combination with other modalities, has demonstrated significant benefit in patients (pts) with microsatellite instability-high or mismatch repair deficient CRC. However, these agents have limited, if any, clinical benefit in pts with microsatellite stable (MSS) or mismatch repair proficient (pMMR) CRC. RP2 is an enhanced potency oncolytic herpes simplex virus type 1 which expresses the fusogenic gibbon ape leukemia virus glycoprotein with the R sequence deleted (GALV-GP-R–), granulocyte-macrophage colony-stimulating factor (GM-CSF), and an anti–CTLA-4 antibody-like molecule; RP3 additionally expresses 4-1BB and CD40 activating ligands, but does not express GM-CSF. Both agents have demonstrated preliminary safety and efficacy in pts with solid tumors. This study will evaluate the safety and efficacy of RP2 and RP3 in combination with atezolizumab (Atezo) and bevacizumab (Bev) in pts with advanced MSS and pMMR CRC. Methods: Pts with a histologic diagnosis of unresectable and/or metastatic CRC, with documented MSS or pMMR status, and previously treated with up to 3 standard-of-care systemic regimens will be enrolled in the RP2 + Atezo + Bev or RP3 + Atezo + Bev treatment groups (30 pts per group). Further key inclusion criteria include Eastern Cooperative Oncology Group performance status 0–1 and adequate hepatic, renal, and hematologic function. RP2/RP3 will be injected into tumors by direct (including via colonoscope) or image-guided injection. Pts will receive 8 total doses of up to 10 mL of RP2 or RP3, with a first dose concentration of 1 × 106 plaque-forming units (PFU)/mL, followed by 3 doses of 1 × 107 PFU/mL every 2 weeks, and then 4 doses of 1 × 107 PFU/mL every 3 weeks. Pts may receive a second course of up to 8 injections of RP2/RP3 if study criteria are met. Bev will be administered starting on day 1 (with first dose of RP2/RP3); Atezo will be administered starting week 7 on the same days as RP2/RP3. The primary endpoint is objective response rate; secondary endpoints are safety, overall survival, progression-free survival, duration of response, and complete response rate. Antitumor activity will be evaluated using Response Evaluation Criteria in Solid Tumors version 1.1 as modified for this study. Safety will be assessed by physical examination, clinical laboratory evaluations, vital signs, and monitoring for adverse events (AEs; including serious AEs). Clinical trial information: NCT05733611 .

3623 Background: Colorectal cancer (CRC) incidence has steadily increased in adults younger than 50 years (EO-CRC) since the 1990s, with a predominance in the left colon and rectum. Precursor lesions of CRCs are adenomas, including advanced adenomas, and sessile serrated polyps. Given that neoplastic development is age-related, we hypothesized that patients with early-onset CRC (EO-CRC) may have fewer adenomas compared to patients with average-onset CRC (AO-CRC) at diagnosis. Methods: We performed a retrospective review of electronic health records at Mayo Clinic or Mayo Health System [2012 to 2021] and randomly selected 150 patients with EO-CRC who met eligibility criteria and matched them with 150 AO-CRC patients based on gender and colonoscopy indication. Known hereditary syndromes or inflammatory bowel disease were excluded. At colonoscopy where CRC was diagnosed, we recorded findings of adenomas, advanced adenomas (> 1 cm, villous histology, or high-grade dysplasia), and sessile serrated polyps (SSP). Results: Median age at diagnosis was 43 years for EO-CRC and 67 years for AO-CRC. No significant differences in BMI, family history of CRC, MMR, BRAFV 600E KRAS status or SSPs were found between groups (all p > 0.05). Among patients with colon cancer, no difference was found for adenoma number yet patients with EO-colon cancer (EO-CC) had larger polyps [median of 10 mm vs 5 mm, p = 0.001] (Table) compared with AO-colon cancer (AO-CC). At least 1 adenoma was found in 56% and 47% of patients with EO-CC and AO-CC, respectively. Moreover, advanced adenomas were significantly more common in the EO-CC group compared with the AO-CC group (42% and 14%, p < 0.001) [ Table]. Among patients with rectal cancer, non-advanced adenomas were less frequent and although advanced adenoma were similar in frequency, they were more commonly located in the rectum in EO-rectal compared to AO-rectal cancers (Table). Conclusions: Patients with EO-colon cancer had a significantly higher likelihood of a synchronous advanced adenoma in the colon compared to those with AO-CRC. Together, these data suggest accelerated carcinogenesis throughout the colorectum in early onset patients, with increased risk for development of synchronous and metachronous CRC. [Table: see text]

3595 Background: PolyPEPI1018 is an off-the-shelf, multi-peptide vaccine containing 12 immunogenic epitopes derived from 7 tumor-specific antigens frequently expressed in patients with mCRC. Following early evidence of clinical activity of PolyPEPI1018 in first-line MSS mCRC, here we report the results of a phase Ib study of PolyPEPI1018 vaccine plus trifluridine/tipiracil (TAS-102) in late-stage mCRC patients. Methods: Patients with MSS mCRC who have progressed on ≤2 lines of prior chemotherapy regimen for mCRC received PolyPEPI1018 subcutaneously on days 1 and 15 and TAS-102 orally twice daily on days 1-5 and 8-15 of a 28-day cycle. Treatment continued for up to 7 cycles, until disease progression or unacceptable toxicity. Immunomonitoring was performed at both blood and tumor levels prior to and on study treatment. The primary endpoint of the study was safety and tolerability. Data on objective response rate (ORR), disease control rate (DCR), progression-free survival (PFS), overall survival (OS) and correlation studies will be presented. Results: 15 patients started treatment. Median age was 55 years (range 31–71), 73% had liver metastases (mets), 73% had KRAS mutant tumors. The most common side effect related to PolyPEPI1018 was Grade (Gr) 1-2 local skin reactions in 93% of patients. Gr 3 events (n = 15) at least possibly related to treatment were fatigue, decreased white blood cell, lymphocyte and neutrophil counts, nausea, diarrhea, myalgia, and maculo-papular rash. There were no Gr 4 or 5 events. The ORR was 0%. The DCR was 53.3% in the overall population and 36% and 100% for the patients with liver mets and without liver mets, respectively. The mPFS was 4 months (95%CI 2.2-6.1) in the overall population and 2.3 months (95%CI 2.1-NE) and 7.6 months (95%CI 4.4-NE) for the patients with liver mets and without liver mets, respectively (HR = 5.73 (95%CI 1.21, 27.06); p = 0.015). At the data cut-off date (Feb 10, 2023), the mOS was 8.7 months (95%CI 6.9-NE; not mature) in the overall population and it was not reached in patients without liver mets. Patients with increased PFS (≥ 24 weeks) had more robust vaccine-specific humoral and T cell responses induced by higher number of vaccine peptides than patients with PFS < 24 weeks. Conclusions: To our knowledge, this is the first study investigating combination of a cancer vaccine with TAS-102 chemotherapy in advanced MSS mCRC. Our results show that PolyPEPI1018 plus TAS-102 was well-tolerated with few grade 3 AEs beyond what is expected with TAS-102 monotherapy. Despite no objective tumor responses could be detected, correlative data suggest contribution of PolyPEPI1018-induced immunological responses to the improved clinical benefit and the combination warrants further testing. Clinical trial information: NCT05130060 .

3588 Background: Although anti-EGFR antibody plus doublet chemotherapy has become the standard of first-line treatment for RAS wild-type (wt), left sided metastatic colorectal cancer (mCRC), the optimal molecular-targeted therapy for RAS wt, right-sided mCRC is not clear. Methods: To evaluate the efficacy between anti-EGFR antibody vs. bevacizumab combination therapy, from 40,889 Individual patient (pt) data from 59 studies in ARCAD mCRC database, 723 pts with RAS wt, right-sided mCRC who received a first-line molecular-targeted therapy with backbone chemotherapy (FOLFOX/FOLFIRI when anti-EGFR antibody combination, and FOLFOX/FOLFIRI/CAPOX/FOLFOXIRI when bevacizumab combination) were selected from 10 randomized studies (FIRE-3, CALGB80495, CRYSTAL, PRIME, CAIRO2, OPUS, TRIBE, TRIBE2, ATOM, and CCOG1201). Primary objective was overall survival (OS), and secondary objectives were progression-free survival (PFS) and overall response rate (ORR); Hazard ratio (HR) and Odds ratio (OR) were adjusted for ECOG-PS, age, and gender. Propensity score matching (PSM) and inverse probability treatment weighting (IPTW) as sensitivity analysis were also performed. Secondary analyses were limited to BRAF wt pts. Results: Anti-EGFR antibody and bevacizumab were administrated in 329 and 394 pts, respectively, of whom 162 and 151 pts were BRAF wt, respectively. Baseline characteristics were as follows (anti-EGFR antibody/bevacizumab): median age, 63.0 years both; female, 47.1/46.4%; and ECOG-PS 0, 53.2/65.2%. The OS and PFS were significantly prolonged in pts receiving bevacizumab combination therapy compared to those receiving anti-EGFR antibody combination therapy (Table). These trends were more pronounced when limited to BRAF wt pts (Table). There were no significant differences in ORR for both overall and BRAF wt pts. These results were similar in the sensitivity analysis (Table). Conclusions: For patients with RAS wt or RAS/ BRAF wt, right-sided mCRC, bevacizumab combination therapy is preferred first-line treatment. [Table: see text]

3580 Background: TAS-102 (FTD/TPI) is a combination of a nucleoside analogue and a thymidine phosphorylase inhibitor, and has showed activity in 5FU-resistant CRC. Nal-IRI achieves higher intra-tumor concentrations than irinotecan (Iri; 142-fold) and its major metabolite, SN-38 (9-fold). This resulted in superior anti-tumor activity compared to free Iri in multiple tumor xenografts. Furthermore, multiple clinical trials have established the activity of nal-IRI in combination with 5FU in pancreaticobiliary cancers. The combination of nal-IRI with the more potent nucleoside analogue TAS-102 may thus result in a more effective systemic therapy. We conducted this study to define the safety and efficacy of the combination of TAS-102 and nal-IRI in advanced CRC. Methods: Eligible patients (pts) on this investigator-initiated phase II study had advanced CRC and must have had disease progression on at least one prior therapy. Additional inclusion criteria - measurable disease, ECOG PS 0-1 & adequate organ function. Based on previously published dose escalation phase I data, the pts were treated at the recommended phase II dose of TAS-102 (given orally at 35mg/m2 bid on days 1-5) and nal-IRI (60mg/m2 IV on day 1) in 14-day cycles. The primary endpoint was objective response rate (ORR) = complete (CR) + partial (PR) response per RECIST v1.1. Multiple secondary endpoints included safety/tolerability, progression-free survival (PFS), overall survival (OS), disease control rate (DCR) and duration of response (DoR). Results: Twenty-two pts were enrolled, of whom 20 were evaluable for response. Male - 50%; ECOG PS 1 – 75%; African Americans – 38%; median age - 58yrs (interquartile range [IQR] 49-67). Median line of prior therapy was 1 (IQR 1-2) and 13.6% (3 pts enrolled during the dose escalation phase) had received prior Iri. 47.6% received concurrent Bevacizumab. ORR was 15% (3 PR, 0 CR). 60% had stable disease (SD) as best response; DCR of 75%. mPFS - 9.7 mos (95% CI: 5.6, 14.2); mOS - 10.1 mos (95% CI: 7.3, 15.9). 12-month PFS and OS rates were 34.6% and 39.5% respectively. At a median follow up of 11.9 mos, DoR was yet to be determined and 50% of the pts had maintained response for 12 mos. Median duration of progression free among pts with SD was 7.6 mos (95% CI: 4.6, 13.2), with a 12-month survival rate of 47.7% (95% CI: 15.5%, 74.5%). Median time to response (TTR) was 4.8mos. Most common treatment related toxicities included fatigue and neutropenia (G3; 27.3% each); anemia and leucopenia (G3; 18.2% each). Other G3 AEs included febrile neutropenia, diarrhea, hypokalemia, lymphopenia and nausea (4.5% each). Conclusions: We demonstrated that the combination of TAS-102 and nal-IRI had an acceptable safety profile, and showed antitumor activity in patients with advanced CRC. Additional biomarker analyses such as survival correlation with UGT1A1 phenotype and RAS mutational status are ongoing. (NCT03368963). Clinical trial information: NCT03368963 .

3579 Background: Panitumumab (Pmab) is a recombinant monoclonal antibody that binds specifically to the human epidermal growth factor receptor (EGFR) and it is indicated for the treatment of metastatic colorectal carcinoma (mCRC). However, the objective response rates (ORR) for the single agent are historically about 8-11%. EGFR inhibition induces synthetic lethality with poly ADP ribose polymerase inhibitors (PARPi) such as Niraparib, by attenuating DNA repair pathways. Combining PARP and EGFR inhibition has the potential to confer synergistic benefit, while also ameliorating resistance mechanism to EGFRi. We conducted this study to define the safety and efficacy of the combination of Niraparib and Pmab in RAS wildtype (WT) mCRC. Methods: Patients (pts) with RAS WT mCRC who have progressed on at least one line of systemic chemotherapy were eligible for the trial. Other selected inclusion criteria were ≥18 years of age, ECOG PS 0-1 and measurable disease per RECIST 1.1. Pmab was administered at 6 mg/kg IV on days 1 & 15 of each 28-day cycle, while Niraparib was taken orally at 200mg or 300mg (based on body weight and platelet count) daily throughout the cycle. The primary endpoint was clinical benefit rate (CBR) defined as complete (CR) + partial (PR) response + stable disease (SD) per RECIST v1.1. Multiple secondary endpoints included safety/tolerability, ORR, progression-free survival (PFS), overall survival (OS), and duration of response (DoR). Results: A safety run-in cohort of 6 pts was initially enrolled. Following a preplanned safety analysis showing an acceptable toxicity profile, an additional 19 pts were enrolled. Of the total 25 enrolled pts, 24 were evaluable for response. Male - 50%; Whites/African Americans/Asians – 65.2%/21.7%/13%; median age – 58.5yrs. The majority had left sided tumor (92%) and the median line of prior therapy was 2 (range 1-4). CBR was 83.3% (0 CR, 6 PR, 14 SD) and ORR was 25%. mPFS – 5.6mos (95% CI: 3.7, 6.9); mOS – 20.9mos (95% CI: 9.2, NR). Six-month PFS and OS rates were 48.4% and 100% respectively. At a median follow up time of 7.5mos (95% CI: 4.2, 10.4), 3 patients remained on treatment and DoR was yet to be determined. Muco-cutaneous adverse events (AEs) of any grade included rash (58.4%), oral mucositis (20.8%), dry skin (16.7%) and paronychia (4.2%). Most common (grade > 2) treatment related AEs (TRAEs) were anemia (G3; 12.5%), dermatitis, oral mucositis, hypertension and neutropenia (G3; 4.2% each). There were no grade 4-5 TRAEs. Conclusions: The combination of Pmab and Niraparib had an acceptable safety profile, and showed considerable antitumor activity in pts with advanced RAS WT mCRC compared to historical rates. Additional biomarker analyses such as survival correlation with immune cell infiltration in paired skin biopsies and HER2/BRAF mutational status are ongoing. Funding and product (Niraparib) for the study were provided by GSK (NCT03983993). Clinical trial information: NCT03983993 .