Regorafenib plus nivolumab in patients with mismatch repair-proficient/microsatellite stable metastatic colorectal cancer: a single-arm, open-label, multicentre phase 2 study

Background

Anti-programmed cell death protein 1 antibodies plus multikinase inhibitors have shown encouraging activity in several tumour types, including colorectal cancer. This study assessed regorafenib plus nivolumab in patients with microsatellite stable/mismatch repair-proficient metastatic colorectal cancer.

Methods

This single-arm, open-label, multicentre phase 2 study enrolled adults from 13 sites in the USA with previously treated advanced microsatellite stable/mismatch repair-proficient metastatic colorectal cancer. Eligible patients had known extended RAS and BRAF status, progression or intolerance to no more than two (for extended RAS mutant) or three (for extended RAS wild type) lines of systemic chemotherapy and an Eastern Cooperative Oncology Group performance status of 0 or 1. Regorafenib 80 mg/day was administered orally for 3 weeks on/1 week off (increased to 120 mg/day if 80 mg/day was well tolerated) with intravenous nivolumab 480 mg every 4 weeks. Primary endpoint was objective response rate. Secondary endpoints included safety, overall survival, and progression-free survival. Exploratory endpoints included biomarkers associated with antitumour activity. Patients who received at least one dose of study intervention were included in the efficacy and safety analyses. Tumour assessments were carried out every 8 weeks for the first year, and every 12 weeks thereafter until progressive disease/end of the study, and objective response rate was analysed after all patients had met the criteria for primary completion of five post-baseline scans and either 10-months' follow-up or drop out. This trial is registered with ClinicalTrials.gov, number NCT04126733.

Findings

Between 14 October 2019 and 14 January 2020, 94 patients were enrolled, 70 received treatment. Five patients had a partial response, yielding an objective response rate of 7% (95% CI 2.4-15.9; p = 0.27). All responders had no liver metastases at baseline. Median overall survival (data immature) and progression-free survival were 11.9 months (95% CI 7.0-not evaluable) and 1.8 months (95% CI 1.8-2.4), respectively. Most patients (97%, 68/70) experienced a treatment-related adverse event; 51% were grade 1 or 2, 40% were grade 3, 3% were grade 4, and 3% were grade 5. The most common (≥20%) events were fatigue (26/70), palmar-plantar erythrodysesthesia syndrome (19/70), maculopapular rash (17/70), increased blood bilirubin (14/70), and decreased appetite (14/70). Higher baseline expression of tumour biomarkers of immune sensitivity correlated with antitumour activity.

Interpretation

Further studies are warranted to identify subgroups of patients with clinical characteristics or biomarkers that would benefit most from treatment with regorafenib plus nivolumab.

Funding

Bayer/Bristol Myers Squibb.

Exploratory biomarker analyses of the single-arm, phase 2 study of regorafenib plus nivolumab in patients (pts) with mismatch repair-proficient (pMMR)/microsatellite stable (MSS) colorectal cancer (CRC)

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Background: Combination treatment with regorafenib (80–120 mg/day, PO, 3 wks on/1 wk off) plus nivolumab (480 mg IV Q4W) showed manageable safety but modest efficacy in a phase 2 study of 70 pts from North America with pMMR/MSS chemotherapy-resistant metastatic CRC (mCRC). Five pts had a partial response (PR; objective response rate [ORR]: 7%); all did not have liver metastases at baseline (n = 5/23; ORR: 22%). One pt had a confirmed complete response (CR) after the primary completion analysis of the study (ASCO 2021). This retrospective exploratory analysis investigated the potential association between specific biomarkers and anti-tumor activity, and how those biomarkers are modulated by treatment with regorafenib plus nivolumab. Methods: In formalin-fixed paraffin-embedded tumor samples obtained at baseline and Cycle (C) 2 Day (D) 8, immune-related biomarkers were assessed via immunohistochemistry (IHC), and RNA sequencing was used for gene expression profiling/gene signatures. Pre-/on-treatment blood samples were collected to measure circulating tumor DNA (ctDNA) and soluble biomarkers. Results: A total of 40 and 27 baseline tumor samples and 14 and 5 paired tumor samples at baseline/C2D8 were available for IHC and RNA sequencing, respectively. Higher baseline protein and mRNA expression of biomarkers for pre-existing immune sensitivity (eg, effector T cells) trended with anti-tumor activity. These biomarkers were expressed at lower levels in pts with liver metastases vs those without liver metastases at baseline. Cytotoxic T cell density was elevated on C2D8 but did not correlate with anti-tumor activity. Increased mean variant allelic frequency in ctDNA at C2D1 predominated in pts with progressive disease (PD), while clearance of ctDNA at C2D1 was only noted for the one pt with a CR. High clonal tumor mutational burden in ctDNA showed a numerical trend with anti-tumor activity (PD vs. SD/PR; P=0.058) and PFS (P = 0.072). Baseline serum levels of select markers related to angiogenesis (eg, vascular endothelial growth factor [VEGF] D) were associated with inferior anti-tumor activity (P = 0.002). Serum levels of immune-related soluble biomarkers (eg, tumor necrosis factor alpha) increased on treatment (P < 0.005), while levels of soluble VEGF receptor 2 decreased (P < 0.001). Conclusions: This study of pts with MSS mCRC treated with regorafenib plus nivolumab suggests that baseline tumor biomarkers for pre-existing immune sensitivity trended with anti-tumor activity, whereas select baseline peripheral biomarkers related to angiogenesis trended with inferior anti-tumor activity. Pharmacodynamics effects were observed, yet no significant correlation with anti-tumor activity was found. Due to the small sample size and retrospective nature, these analyses are hypothesis-generating. Clinical trial information: NCT04126733.

Single-arm, phase 2 study of regorafenib plus nivolumab in patients with mismatch repair-proficient (pMMR)/microsatellite stable (MSS) colorectal cancer (CRC)

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Background: The role of immunotherapy in the treatment of pMMR/MSS metastatic CRC is not established. A Japanese phase 1b trial in this setting showed the combination of regorafenib (multikinase inhibitor with immunomodulatory activity) plus nivolumab (anti PD-1) had encouraging activity and manageable safety (Fukuoka, 2020). This study further assessed the safety and efficacy of this combination. Methods: Patients (pts) from the US aged ≥18 years who progressed on/were intolerant to standard chemotherapy were enrolled. Regorafenib was given orally, once daily in 28-day (D) cycles (21D on/7D off) plus IV nivolumab 480 mg on D1. Regorafenib starting dose was 80 mg; if well tolerated, it could be escalated to 120 mg in Cycle 2. Primary endpoint was overall response rate (ORR; RECIST 1.1); secondary aims included disease control rate (DCR), overall survival (OS), progression-free survival (PFS), and safety (NCI-CTCAE v5.0 grade). Biomarker analysis was exploratory. Results: 70 pts (59% male) started treatment. At baseline, median age was 57 years (range 34–85), ECOG PS 0/1 was 51%/49%, 67% had liver metastases (mets), and the primary tumor site was right-sided colon in 36% and rectum in 17%. Median number of cycles was 3.0 (range 1–13); 41% of pts escalated regorafenib to 120 mg. Five pts (7.1%) had a partial response (PR) lasting ≥16 weeks (wks) and 22 (31.4%) had stable disease (SD); pts without liver mets had a higher ORR (21.7%). In pts with tumor samples (n = 40), higher baseline expression (IHC) of cytotoxic T cells (CD3+/CD8+/GranzymeB+), Tregs (FoxP3+), and macrophages (CD68+) trended with clinical benefit (PR/SD ≥16 wks/PFS); pts with liver mets had lower expression. Lower plasma levels of biomarkers of vascular biology (e.g. VEGF-D, Ang-2, VWF) trended with longer PFS. Grade (Gr) 3 treatment-emergent adverse events (TEAEs) occurred in 53% of pts and Gr 4 in 10%. Three pts had a Gr 5 TEAE: n = 1 related to the combination (sepsis); n = 1 related to nivolumab only by investigator (sepsis); n = 1 unrelated to treatment (respiratory failure). Most common Gr 3/4 TEAEs: maculopapular rash (14%), fatigue (7%), pneumonia (6%), increased bilirubin (6%). Conclusions: Combination treatment with regorafenib (up to 120 mg/day) and nivolumab (480 mg every 28D) has manageable safety. Efficacy of this combination in the North American population did not emulate results in the Japanese population. Absence of liver mets and expression of specific biomarkers indicate a better response and may warrant further analysis. Clinical trial information: NCT04126733. [Table: see text]