Lack of Benefit From Anti-EGFR Treatment in RAS and BRAF Wild-type Metastatic Colorectal Cancer With Mucinous Histology or Mucinous Component

Prognostic impact of depth of response and early tumour shrinkage in patients with BRAF V600E -mutated metastatic colorectal cancer treated with targeted therapy

Background

Encorafenib plus cetuximab (EC) is the standard of care for pre-treated BRAF V600E mutated metastatic colorectal cancer (mCRC). Depth of response (DpR) and early tumour shrinkage (ETS) previously showed a strong correlation with survival outcomes of first-line chemotherapy ± biological agents.

Objectives

We aimed to assess potential predictors of primary resistance to EC ± binimetinib (B) and relationships of DpR/ETS with survival outcomes and clinical characteristics.

Design

This is a retrospective real-world cohort study of BRAF V600E mutated mCRC patients treated with second-line EC ± B at 20 Italian centres.

Methods

Measurable disease according to Response Evaluation Criteria In Solid Tumour (RECIST) 1.1 at baseline and at least one subsequent computed tomography (CT) scan were mandatory for inclusion. Clinical features associated with primary resistance, DpR and ETS were investigated. Relationships of DpR and ETS, both as binary, according to conventional (30% for DpR and 20% for ETS) and median cut-off values, and continuous variables, with progression-free (PFS), overall survival (OS) and duration of response (DoR) were assessed in non-primary resistant patients.

Results

A total of 105 patients were included. The primary resistance rate was 28% (29/105) and was associated with baseline peritoneal metastases (p = 0.04). Disease control and overall response rates were 72% (76/105) and 24% (25/105), respectively, with a median DpR of 15% and an ETS rate of 37% (28/76). Mucinous histology was associated with a significantly lower magnitude of DpR (p = 0.005) and a lower rate of ETS (p = 0.002). In the multivariable models, DpR significantly correlated with longer PFS as a dichotomous variable, according both to conventional (hazard ratio (HR)DpR ⩾ 30%: 0.52, 95% CI: 0.30-0.90, p = 0.02) and median cut-off values (HRDpR⩾15%: 0.55, 95% CI: 0.33-0.92, p = 0.03), and as a continuous variable (HR per 10% increment: 0.88, 95% CI: 0.78-0.98, p = 0.02), while correlations with OS were not confirmed. DpR was also significantly associated with longer DoR (p DpR⩾30% = 0.04; p DpR⩾15% = 0.04; p cont. = 0.02), whereas no relationships of ETS with PFS, OS or DoR were detected.

Conclusion

A DpR of at least 15% independently predicts PFS benefit in BRAF V600E mutated mCRC patients treated with second-line EC ± B.

Impact of primary tumor resection on the survival of patients with unresectable colon cancer liver metastasis at different colonic subsites: a propensity score matching analysis

OBJECTIVE

To investigate the effect of primary tumor resection (PTR) on the prognosis of patients with unresectable colon cancer liver metastasis (UCCLM) at seven colonic subsites using the Surveillance, Epidemiology, and End Results (SEER) database.

METHODS

Propensity score matching (PSM) was performed to balance selection bias using all available variables that could be of potential relevance. After matching, the groups were redefined in a 1:1 ratio using the nearest method. Cancer-specific survival (CSS) was compared among the patients of PTR and non-PTR groups. Cox regression models were used to identify the prognostic factors for CSS.

RESULTS

CSS was significantly different between all groups. Cox regression analysis showed that PTR was an independent prognostic factor for all groups. After PSM, PTR significantly prolonged CSS for all groups. Subgroup analysis showed that PTR did not improve the prognosis of N2 stage patients in the cecum, ascending colon, and descending colon groups; T1 + T2 stage patients in the hepatic flexure group; and patients with a tumor size ≤5 cm in the splenic flexure group. Segmental colectomy could prolong CSS of patients in the cecum, ascending colon, transverse colon, splenic flexure, and sigmoid colon groups, while extended colectomy could prolong CSS of patients in the hepatic flexure and descending colon groups.

CONCLUSION

At different colonic subsites, UCCLM patients had different CSS. PTR could improve their prognosis, however, N stage, T stage, and tumor size are important reference indicators. In addition to patients in the hepatic flexure and descending colon groups, we suggested that patients in other groups should choose segmental colectomy.

Mucinous Histology Is Associated with Resistance to Anti-EGFR Therapy in Patients with Left-Sided RAS/BRAF Wild-Type Metastatic Colorectal Cancer

BACKGROUND

Limited studies have suggested that mucinous histology is associated an attenuated response to anti-epidermal growth factor receptor (EGFR) therapy.

METHODS

We conducted a single-institution, retrospective study to review the anti-EGFR response and the molecular profile of patients with left-sided microsatellite stable RAS/BRAF wild-type mucinous metastatic colorectal cancer.

RESULTS

In comparison to nonmucinous population (n = 98), mucinous histology (n = 20) was associated with a younger age (48 vs 54, P = .02), wild-type APC (80% vs 15.3%, P < .0001), and wild-type TP53 (40% vs 8.2%, P = .001). Guanine nucleotide binding protein, alpha stimulating (GNAS) mutations were exclusively found in mucinous tumors (20% vs 0, P < .0001). Genomic alterations associated with resistance to anti-EGFR therapy, such as ERBB2 amplification, PIK3CA mutation, MAP2K1 mutation, and KRAS amplification, were identified in patients with left-sided RAS/BRAF wild-type mucinous metastatic colorectal cancer. Mucinous histology was not associated with a worse outcome than non-mucinous histology (34.3 vs 42.2 months, P = .85). However, patients with left-sided RAS/BARF wild-type mucinous colorectal cancer treated with first-line anti-EGFR therapy had significantly worse progression-free survival (4 vs 6.5 months, hazard ratio [HR] = 5.3, 95% confidence interval [CI] 1.3-21.7, P = .01) than patients treated with the first-line vascular endothelial growth factor A antibody, bevacizumab. Anti-EGFR therapy was associated with limited responses and a short PFS across all lines of therapy in 12 patients with left-sided RAS/BRAF wild-type mucinous colorectal cancer.

CONCLUSIONS

Mucinous histology is associated with diminished benefits from anti-EGFR therapy in patients with left-sided RAS/BRAF wild-type colorectal cancer. These patients should be considered for bevacizumab-based therapy in the first- and second-line settings.

Clinicians' Attitude to Doublet Plus Anti-EGFR Versus Triplet Plus Bevacizumab as First-line Treatment in Left-Sided RAS and BRAF Wild-Type Metastatic Colorectal Cancer Patients: A Multicenter, "Real-Life", Case-Control Study

BACKGROUND

Doublets plus antiepidermal growth factor receptors monoclonal antibodies (EGFRi) are widely considered the preferable first-line regimen in patients with left-sided RAS/BRAF wild-type metastatic colorectal cancer (mCRC), resulting superior in terms of activity and efficacy compared to doublets plus bevacizumab. However, data comparing doublet plus EGFRi and triplet plus bevacizumab are lacking, and the relative benefit of an intensive regimen plus an antiangiogenic backbone in this population is debated.

METHODS

This multicenter, retrospective study aimed at evaluating clinicians' attitude to triplet-bevacizumab and doublet-EGFRi as first-line regimen in patients with left-sided RAS/BRAF wild-type mCRC treated in clinical practice at 22 Oncology Units from March 2012 to October 2020. A random case-control matching was performed to compare activity (ORR), and effectiveness (PFS, OS, secondary resection rate of metastases with curative intent) between triplet-bevacizumab and doublet-EGFRi, on the basis of ECOG-PS, age, gender, and burden of disease.

RESULTS

A total of 718 patients were consecutively treated with doublet-EGFRi (686, 95.5%) or triplet-bevacizumab (32, 4.5%). After case-control matching, median PFS was 13.6 (95% CI, 8.9-31.7) and 16.1 (95% CI, 12.1-36.8) months (P= .621), while median OS was 30.2 (95% CI, 14.4-69.5) and 38.1 (95% CI, 33.1-101.1) months (P= .0283) in the doublet-EGFRi and the triplet-bevacizumab cohort, respectively. The ORR was 65.6% and 90.6% (P= .016), while the secondary resection rate was 18.8% and 46.9% (P= .016), in the doublet-EGFRi and the triplet-bevacizumab cohort, respectively. Triplet-bevacizumab was associated with a higher incidence of G3/G4 neutropenia (25.0% vs. 12.5%, P= .041).

CONCLUSION

Although a doublet-EGFRi remains the recommended upfront regimen in patients with left-sided RAS and BRAF wild-type mCRC, our real life data suggest a triplet-bevacizumab might be at least equally active and effective in properly selected cases.

Distinct Genomic Landscape of Colorectal Mucinous Carcinoma Determined via Comprehensive Genomic Profiling: Steps to a New Treatment Strategy

Colorectal mucinous carcinoma (MC) is associated with inferior prognosis and response to treatment compared to adenocarcinoma (AC). The molecular landscapes of MC and adenocarcinoma with mucous composition (AMC) are not well-defined. We aimed to describe the genomic landscape of MC and AMC in a large colorectal cancer cohort. Tumor samples from patients with MC, AMC, or AC were analyzed using next-generation sequencing. MC had a molecular signature distinct from that of AC; genomic features were similar between AMC and MC but not between AMC and AC. HER2 amplification and TP53 and APC mutation rates were lower, whereas SMAD4, PIK3CA, ACVR2A, KMT2D, LRP1, TGFBR2, GRIN2A, BRAF V600E, PTEN, and BRCA2 mutation rates were higher in MC than in AC. The mutation frequencies in MAPK, PI3K, and TGF- pathways were higher, whereas those of cell cycle proteins and Wnt were lower in MC and AMC than in AC. The proportion of hypermutated tumors was significantly higher in MC and AMC than in AC. As MC has a distinct molecular signature from AC, immunotherapy can be potentially applied in treating MC. Similar molecular profiles of AMC and MC suggest that treatment strategies for MC, but not AC, can be used for AMC treatment.

First-line therapy of bevacizumab plus chemotherapy versus cetuximab plus chemotherapy for metastatic colorectal cancer patients with mucinous adenocarcinoma or mucinous component

Background

To compare the efficacy of first‐line bevacizumab plus chemotherapy with cetuximab plus chemotherapy based on the stratification of metastatic colorectal cancer (mCRC) patients with mucinous adenocarcinoma (MA) or mucinous component (MC).

Methods

A retrospective study involving all mCRC patients receiving first‐line bevacizumab‐based or cetuximab‐based chemotherapy at our hospital from September 2013 to January 2020 was conducted. Overall survival (OS), progression‐free survival (PFS), and objective response rate (ORR) were compared between the cetuximab‐chemotherapy group and the bevacizumab‐chemotherapy group on the basis of the conventional pathological classification of MA or MC.

Results

A total of 620 patients with mCRC were included in our study, consisting of 141 (22.7%) patients with MA/MC and 479 (77.3%) patients with non‐mucinous adenocarcinoma (NMA). In the MA/MC cohort, patients who were treated with bevacizumab‐based chemotherapy were associated with significantly better OS than those treated with cetuximab‐base chemotherapy (30.0 vs. 26.3 months, p = 0.002), irrespective of tumor sites. The efficacy of bevacizumab‐based chemotherapy was higher in nearly all subgroups as shown in the subgroup analysis. In the NMA cohort, median OS was better in the cetuximab plus chemotherapy group than that in the bevacizumab plus chemotherapy group (32.2 vs. 27.0 months, p = 0.005) for left‐side mCRC patients, whereas OS was significantly longer in the bevacizumab plus chemotherapy group for right‐side mCRC patients (26.0 vs. 20.9 months, p = 0.013).

Conclusion

Conventional pathological classification (e.g. MA/MC) should be considered when tailoring the individualized optimal treatment for mCRC. Bevacizumab plus chemotherapy as first‐line therapy may be the optimal option for patients with MA/MC.

Does the efficacy of regorafenib differ in chemotherapy refractory metastatic colorectal cancer patients who had mucinous pathology compared to those who had non-mucinous pathology?

PURPOSE

To investigate the importance of mucinous histopathology on the assessment of tumor response in patients with metastatic colorectal cancer (mCRC) receiving regorafenib.

MATERIALS AND METHOD

All patients diagnosed with histologically confirmed mCRC in 2 oncology centers between 2013 and 2018 were retrospectively analyzed. Among 678 patients diagnosed with mCRC, 103 patients were treated with regorafenib. Ninety-four of these patients who had used at least 2 cycles of regorafenib and evaluable for treatment response were included in the analysis. Histopathologically, 18 patients with mucinous adenocarcinoma and 76 patients with nonmucinous adenocarcinoma were compared in terms of response rate and survival durations.

RESULTS

Median follow-up duration of 6 months, median age of the patients was 61 (34-77) years. While 19.1% of the patients had mucinous histology, 80.9% had nonmucinous histology. The overall response rate was significantly lower in the mucinous subgroup than the nonmucinous subgroup (5.6% vs 43.4%, respectively, P = 0.003). Similarly, both progression-free survival (3.0 vs 4.0 months, respectively, P = 0.011) and overall survival duration were shorter in the mucinous subgroup (3.0 vs 7.0 months, P = 0.016, respectively) compared with the nonmucinous subgroup.

CONCLUSION

The histological subgroup may predict tumor response in mCRC patients receiving regorafenib. Its efficacy on nonmucinous histology had significantly more favorable than mucinous subtype.