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PURPOSE This phase II study evaluated the efficacy and tolerability of onvansertib, a polo-like kinase 1 (PLK1) inhibitor, in combination with fluorouracil, leucovorin, and irinotecan (FOLFIRI) + bevacizumab for the second-line treatment of KRAS -mutant metastatic colorectal cancer (mCRC). PATIENTS AND METHODS This multicenter, open-label, single-arm study enrolled patients with KRAS -mutated mCRC previously treated with oxaliplatin and fluorouracil with or without bevacizumab. Patients received onvansertib (15 mg/m 2 once daily on days 1-5 and 15-19 of a 28-day cycle) and FOLFIRI + bevacizumab (days 1 and 15). The primary end point was the objective response rate (ORR), and secondary endpoints included progression-free survival (PFS), duration of response (DOR), and tolerability. Translational and preclinical studies were conducted in KRAS -mutant CRC. RESULTS Among the 53 patients treated, the confirmed ORR was 26.4% (95% CI, 15.3 to 40.3). The median DOR was 11.7 months (95% CI, 9.4 to not reached). Grade 3/4 adverse events were reported in 62% of patients. A post hoc analysis revealed that patients with no prior bevacizumab treatment had a significantly higher ORR and longer PFS compared with patients with prior bevacizumab treatment: ORR of 76.9% versus 10.0% (odds ratio of 30.0, P < .001) and median PFS of 14.9 months versus 6.6 months (hazard ratio of 0.16, P < .001). Our translational findings support that prior bevacizumab exposure contributes to onvansertib resistance. Preclinically, we showed that onvansertib inhibited the hypoxia pathway and exhibited robust antitumor activity in combination with bevacizumab through the inhibition of angiogenesis. CONCLUSION Onvansertib in combination with FOLFIRI + bevacizumab showed significant activity in the second-line treatment of patients with KRAS -mutant mCRC, particularly in patients with no prior bevacizumab treatment. These findings led to the evaluation of the combination in the first-line setting (ClinicalTrails.gov identifier: NCT06106308 ).

Abstract Purpose: Onvansertib is a highly specific inhibitor of polo-like kinase 1 (PLK1), with demonstrated safety in solid tumors. We evaluated, preclinically and clinically, the potential of onvansertib in combination with chemotherapy as a therapeutic option for KRAS-mutant colorectal cancer. Patients and Methods: Preclinical activity of onvansertib was assessed (i) in vitro in KRAS wild-type and -mutant isogenic colorectal cancer cells and (ii) in vivo, in combination with irinotecan, in a KRAS-mutant xenograft model. Clinically, a phase Ib trial was conducted to investigate onvansertib at doses 12, 15, and 18 mg/m2 (days 1–5 and 14–19 of a 28-day cycle) in combination with FOLFIRI/bevacizumab (days 1 and 15) in patients with KRAS-mutant metastatic colorectal cancer who had prior oxaliplatin exposure. Safety, efficacy, and changes in circulating tumor DNA (ctDNA) were assessed. Results: In preclinical models, onvansertib displayed superior activity in KRAS-mutant than wild-type isogenic colorectal cancer cells and demonstrated potent antitumor activity in combination with irinotecan in vivo. Eighteen patients enrolled in the phase Ib study. Onvansertib recommended phase II dose was established at 15 mg/m2. Grade 3 and 4 adverse events (AE) represented 15% of all treatment-related AEs, with neutropenia being the most common. Partial responses were observed in 44% of patients, with a median duration of response of 9.5 months. Early ctDNA dynamics were predictive of treatment efficacy. Conclusions: Onvansertib combined with FOLIFRI/bevacizumab exhibited manageable safety and promising efficacy in second-line treatment of patients with KRAS-mutant metastatic colorectal cancer. Further exploration of this combination therapy is ongoing. See related commentary by Stebbing and Bullock, p. 2005

Metastatic colorectal cancer (mCRC) is a heterogeneous disease that can evoke discordant responses to therapy among different lesions in individual patients. The Response Evaluation Criteria in Solid Tumors (RECIST) criteria do not take into consideration response heterogeneity. We explored and developed lesion-based measurement response criteria to evaluate their prognostic effect on overall survival (OS). Patients and Methods: Patients enrolled in 17 first-line clinical trials, who had mCRC with ≥ 2 lesions at baseline, and a restaging scan by 12 weeks were included. For each patient, lesions were categorized as a progressing lesion (PL: > 20% increase in the longest diameter (LD)), responding lesion (RL: > 30% decrease in LD), or stable lesion (SL: neither PL nor RL) based on the 12-week scan. Lesion-based response criteria were defined for each patient as follows: PL only, SL only, RL only, and varied responses (mixture of RL, SL, and PL). Lesion-based response criteria and OS were correlated using stratified multivariable Cox models. The concordance between OS and classifications was measured using the C statistic. Results: Among 10,551 patients with mCRC from 17 first-line studies, varied responses were noted in 51.6% of patients, among whom, 3.3% had RL/PL at 12 weeks. Among patients with RL/SL, 52% had stable disease (SD) by RECIST 1.1, and they had a longer OS (median OS (mOS) = 19.9 months) than those with SL only (mOS = 16.8 months, HR (95% CI) = 0.81 (0.76, 0.85), p < 0.001), although a shorter OS than those with RL only (mOS = 25.8 months, HR (95% CI) = 1.42 (1.32, 1.53), p < 0.001). Among patients with SL/PL, 74% had SD by RECIST 1.1, and they had a longer OS (mOS = 9.0 months) than those with PL only (mOS = 8.0 months, HR (95% CI) = 0.75 (0.57, 0.98), p = 0.040), yet a shorter OS than those with SL only (mOS = 16.8 months, HR (95% CI) = 1.98 (1.80, 2.18), p < 0.001). These associations were consistent across treatment regimen subgroups. The lesion-based response criteria showed slightly higher concordance than RECIST 1.1, although it was not statistically significant. Conclusion: Varied responses at first restaging are common among patients receiving first-line therapy for mCRC. Our lesion-based measurement criteria allowed for better mortality discrimination, which could potentially be informative for treatment decision-making and influence patient outcomes.

118 Background: Anti-VEGF is widely used in the treatment (trt) of metastatic colorectal cancer (mCRC). Only studies with bevacizumab (BEV) have shown survival benefit (bnf) in first line trt. The magnitude of bnf might differ based on the metastatic (met) site and the chemotherapy regimen (CTR) with which BEV is partnered. ARCAD database contains individual patient data (IPD) of randomized trials that evaluated BEV+ CT. In this pooled analysis, we aimed to evaluate BEV bnf in mCRC with lung metastases (mets) either as single or multiple sites. Methods: IPD from four trials (AVF2107g, N016966, AVF2192g, AGITG) comparing CT +/- BEV were pooled. The primary endpoint, overall survival (OS), was estimated using Kaplan-Meier method and prognostic value of lung mets was evaluated by stratified Cox models according to number and type of met sites and CTRs, oxaliplatin or irinotecan (OX/IRI) based. The predictive bnf of BEV was evaluated by interaction test (int) between trt and lung mets status in subgroups and considered as significant (sig) with a P < 0.1. Results: 2728 patients (pts) with known met sites and survival data were pooled. 1020 pts had single met site, 133 had only lung mets. 1708 pts had multiple met sites, 1008 had lung mets. Pts characteristics were well balanced. Sig OS bnf of BEV was observed in the whole population. In pts subgroup according to the presence or absence of lung mets, sig bnf of BEV were observed with a non-sig int ( Pint=.590). Non-sig bnf of BEV was observed in pts with single site regardless of met site (lung or no lung) or CTR. Sig bnf of BEV was observed in pts with multiple sites without lung mets whatever the CTRs. While sig bnf of BEV was observed in pts with multiple sites with lung mets, we found a sig int between BEV and OX/IRI-based regimens ( Pint=.022). The bnf of BEV was observed with IRI-based regimen but not in OX-based regimen. The bnf of BEV appears greater in multiple sites without lung mets than with lung mets with a sig stratified log-rank test ( PLRT<.001). Conclusions: In pts with multiple sites mCRC, a statistically sig OS bnf of BEV added to CT was observed mainly among pts without lung mets. The overall effect of CT partner choice when combined with BEV can be different. In pts with single site, BEV did not seem to improve OS but the evaluation of efficacy of BEV in presence or absence lung mets was based on small number of pts and needs to be evaluated in trials with larger pts sample, especially trials including pts with single site lung mets. [Table: see text]

80 Background: Higher baseline body mass index is associated with improved survival in metastatic CRC (mCRC). Whether weight gain or loss after mCRC diagnosis is associated with survival remains largely unknown. Methods: We analyzed individual patient data from 3504 patients with previously untreated mCRC enrolled in five phase III randomized trials (AVF2017g, AVF2192g, CRYSTAL, N9741, OPUS) conducted between 2000 and 2006. Weight measurements were prospectively collected at 3 months after diagnosis and then up to 5 years. Patients were categorized into three groups based on the percent weight change at 3 months: stable weight or gain, weight loss up to 5% of baseline weight, and ≥5% weight loss of baseline weight. Cox models were used to assess the prognostic associations of weight change at 3 months with overall survival (OS) and progression-free survival (PFS), adjusting for baseline BMI, age, sex, performance score, chemotherapy backbone (oxaliplatin vs. irinotecan), and biologics type (cetuximab vs. bevacizumab). Sub-analyses included Cox models adjusted for additional clinical-pathological factors (primary tumor sidedness [right colon vs. left colon-rectum], and BRAF status; N=1,511). Results: Median percent weight change at 3 months was -0.5% (IQR -4.0 to+1.6%). OS was better in patients with weight stability or gain than in those with weight loss (up to 5% or ≥5%; (Table). Results were consistent for PFS for patients with ≥5% weight loss of baseline weight, as well as for sub-analyses. Conclusions: Patients losing weight during the first 3 months of systemic therapy for metastatic colorectal cancer have significantly shorter overall survival than those with stable or increasing weight. Degree of weight loss is proportional to the observed increased risk of death and remains evident among underweight, normal weight and obese individuals. Further studies examining possible usefulness of on-treatment early weight loss as a novel intermediary end-point are needed.[Table: see text]

Background: Benchmarking international cancer survival differences is necessary to evaluate and improve healthcare systems. Our aim was to assess the potential regional differences in outcomes among patients with metastatic colorectal cancer (mCRC) participating in international randomized clinical trials (RCTs). Design: Countries were grouped into 11 regions according to the World Health Organization and the EUROCARE model. Meta-analyses based on individual patient data were used to synthesize data across studies and regions and to conduct comparisons for outcomes in a two-stage random-effects model after adjusting for age, sex, performance status, and time period. We used mCRC patients enrolled in the first-line RCTs from the ARCAD database, which provided enrolling country information. There were 21,509 patients in 27 RCTs included across the 11 regions. Results: Main outcomes were overall survival (OS) and progression-free survival (PFS). Compared with other regions, patients from the United Kingdom (UK) and Ireland were proportionaly over-represented, older, with higher performance status, more frequently male, and more commonly not treated with biological therapies. Cohorts from central Europe and the United States (USA) had significantly longer OS compared with those from UK and Ireland ( p = 0.0034 and p < 0.001, respectively), with median difference of 3–4 months. The survival deficits in the UK and Ireland cohorts were, at most, 15% at 1 year. No evidence of a regional disparity was observed for PFS. Among those treated without biological therapies, patients from the UK and Ireland had shorter OS than central Europe patients ( p < 0.001). Conclusions: Significant international disparities in the OS of cohorts of mCRC patients enrolled in RCTs were found. Survival of mCRC patients included in RCTs was consistently lower in the UK and Ireland regions than in central Europe, southern Europe, and the USA, potentially attributed to greater overall population representation, delayed diagnosis, and reduced availability of therapies.

9068 Background: The phase 2 SUMMIT basket trial (NCT01953926) demonstrated efficacy of neratinib in patients with EGFR exon 18-mutant NSCLC [Boni et al. WCLC 2020]. Neratinib also has documented activity in HER2+ metastatic breast cancer with CNS metastases [Saura et al. SABCS 2020 & J Clin Oncol 2020]. Here we report neratinib efficacy in a subgroup of patients with EGFR exon 18-mutant NSCLC and CNS involvement from SUMMIT. Methods: Patients with EGFR exon 18-mutant NSCLC were treated with single-agent neratinib (240 mg po daily). Prior EGFR tyrosine kinase inhibitors (TKIs), chemotherapy, and checkpoint inhibitors (IO) were allowed. Patients with stable, asymptomatic CNS metastasis were enrolled. Study endpoints: objective response rate (ORR) at week 8 (±1 week); ORR (RECIST 1.1 confirmed); duration of response (DOR); clinical benefit rate (CBR); progression-free survival (PFS); safety; biomarkers. Results: Baseline characteristics of 11 patients with EGFR exon 18-mutant NSCLC: median age 67 (range 56–83) years; ECOG PS 0/1 (45%/55%). Prior lines of therapies: 2 (range 1–3): EGFR TKIs (91%); chemotherapy (55%); IO (27%). 3/11 patients had baseline CNS metastasis and received radiation 8–22 months prior to study enrollment. Best CNS response in these 3 patients was stable disease with overall individual PFS of 1.9 (censored), 6.9 and 9.1 months and OS of 2.6 (censored), 17.7 (censored), and 17.9 months. Efficacy is summarized in Table. Efficacy summary: TKI-pretreated EGFR exon 18-mutant NSCLC cohort receiving neratinib monotherapy. Conclusions: Activity of single-agent neratinib was observed in prior TKI-exposed patients with EGFR exon 18-mutant NSCLC. Despite the small sample size of only 3 patients with baseline CNS metastases, findings suggest a potential role for neratinib as a systemic treatment option for patients with NSCLC and difficult-to-treat uncommon mutations with CNS involvement. The SUMMIT trial continues to enroll patients with EGFR exon 18-mutant NSCLC. Clinical trial information: NCT01953926. [Table: see text]

3520 Background: EOTR has been suggested as a potential surrogate for overall survival (OS) in patients (pts) with mCRC and allows early assessment of treatment efficacy, facilitating adaptive trial design. We assessed at the individual patient level, the correlation between EOTR (complete or partial response) at 6, 8 and 12 weeks (wk), OS and progression free survival (PFS) in pts with mCRC treated with 1stline chemotherapy with or without a targeted agent as a first step in a surrogacy demonstration. Methods: IPD from 13,949 pts enrolled on 15 randomized Phase III trials in 1st line mCRC were used; 8 trials included targeted (anti-angiogenic and anti-EGFR) agents. EOTR prognostic value was assessed by landmark analyses using Cox models stratified by treatment assignment. P-values <0.01 were considered statistically significant to account for multiple comparisons. Results: Of 13,949 pts, 11,987 had sufficient response data to be included in the analysis. Median OS was 21.7 months (mo) in pts with an EOTR vs. 16.5 mo without EOTR at 6 wk (p<.0001, Hazard Ratio [HR] 0.64, 95% confidence interval [CI] 0.58-0.70, c statistic [c] 0.55). HRs were similar whether pts were treated with targeted therapies (p<.0001, HR 0.68, 95% CI 0.58-0.80, x 0.54) or non-targeted therapies (p<.0001, HR 0.61, 95% CI 0.55-0.69, x 0.55). Median PFS was 8.4 mo in pts with EOTR at 6 wk vs. 7.0 mo in pts without EOTR (p<.0001, HR 0.79, 95% CI 0.73-0.85). EOTR at 8 and 12 wks were also significantly associated with longer OS and PFS. The prognostic value of EOTR at 6, 8 and 12 wks remained significant (p<0.0001) after adjusting for age, gender, performance statusand location of metastatic disease (lung or liver). Overall tumor response (to 26 wk) however provided superior OS prediction (p<.0001, HR 0.51, 95% CI, 0.47-0.56, CS 0.61) vs. EOTR. Conclusions: Early response measured at 6, 8 or 12 wk after starting 1st line treatment was a strong and independent predictor of both OS and PFS in patient with mCRC and warrants further consideration as a potential endpoint for future trials, particularly randomized phase II trials.

Abstract Background Platinum chemotherapy (carboplatin or cisplatin) + etoposide is the current 1L standard of care treatment (tx) for ES-SCLC. Despite high response rates on this regimen, patient (pt) outcomes remain poor. IMpower133 is a Ph1/3, double-blind, randomized, placebo (PBO)-controlled trial that is evaluating the efficacy and safety of adding PD-L1-inhibitor atezo or PBO to 1L tx for ES-SCLC (NCT02763579). Methods IMpower133 enrolled pts without prior tx for ES-SCLC; PD-L1 testing was not required. Pts were randomized 1:1 to four 21-day cycles of carboplatin (AUC 5 mg/mL/min IV, Day 1) + etoposide (100 mg/m2 IV, Days 1-3) with either atezo (1200 mg IV, Day 1) or PBO, then maintenance atezo or PBO until PD, unacceptable toxicity or loss of clinical benefit. Maintenance prophylactic cranial irradiation (PCI) was allowed per protocol, while definitive thoracic radiation (TR) was not. Coprimary endpoints were OS and investigator-assessed PFS. A key exploratory endpoint was outcomes by blood tumor mutation burden (bTMB) analyzed at prespecified cutoffs (≥ 16 vs &lt; 16 and ≥ 10 vs &lt; 10 mutations/Mb). Results Adding atezo to carboplatin + etoposide demonstrated significant improvement in efficacy (OS and PFS) in 1L ES-SCLC (Table). Survival benefits were consistent across key subgroups and prespecified bTMB cutoffs. 44 pts (22 in each arm [per ITT]) received PCI, and 7 (3 in atezo arm, 4 in PBO arm) received TR. Gr 3-4 tx-related adverse events (AEs) occurred in 57% of atezo pts vs 56% of PBO pts; serious tx-related AEs occurred in 23% vs 19%. Occurrence of CNS-related AEs in pts who had PCI are shown in the Table. Conclusion Adding atezo to carboplatin + etoposide resulted in a significant improvement in survival in this 1L ES-SCLC all-comers population. There were no new safety signals, including in pts who received PCI or TR. Atezo + carboplatin + etoposide may represent a new standard regimen for untreated ES-SCLC. Atezo + carboplatin + etoposiden = 201PBO + carboplatin + etoposiden = 202Co-primary endpointsMedian OS, mo12.310.3HR 0.70 (95% CI: 0.54, 0.91); P = 0.0069Median PFS, mo5.24.3HR 0.77 (95% CI: 0.62, 0.96) P = 0.017Secondary efficacy endpointsInvestigator-assessed confirmed ORR, %60.264.4Median DoR, mo4.23.9CNS-related AEs in pts who had PCI, n (%)a,bn = 23n = 21Headache8 (34.8)4 (19.0)Asthenia5 (21.7)2 (9.5)Dizziness2 (8.7)0Insomnia2 (8.7)1 (4.8)Fall2 (8.7)1 (4.8)aSafety population; safety analyses conducted according to tx received (1 pt randomized to the control arm received a dose of atezo).bIncludes AEs occurring in ≥ 2 patients. Citation Format: Aaron S. Mansfield, Stephen V. Liu, Aleksandra Szczęsna, Libor Havel, Maciej Kzrakowski, Maximilian J. Hochmair, Florian Huemer, György Losonczy, Melissa L. Johnson, Makoto Nishio, Martin Reck, Tony S. Mok, Sivuonthanh Lam, David S. Shames, Juan Liu, Fairooz Kabbinavar, Alan Sandler, Leora Horn. IMpower133: Primary efficacy and safety + CNS-related adverse events in a Ph1/3 study of first-line (1L) atezolizumab (atezo) + carboplatin + etoposide in extensive-stage SCLC (ES-SCLC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr CT199.