mCRC Cases Research Articles

Clinical impact of TP53 functional mutations in patients with metastatic colorectal cancer treated with bevacizumab and chemotherapy.

Clinical and experimental studies indicate that the tumor protein p53 (TP53) gene loss of function due to missense mutations (MMs) may confer sensitivity to anti-angiogenics. This effect seems to be linked to cross-talk mechanisms among TP53, vascular endothelial growth factor (VEGF), and VEGF receptors. We investigated whether specific TP53 MMs are associated with clinical outcomes of patients with metastatic colorectal cancer (mCRC) treated with first-line chemotherapy plus Bevacizumab. The study focused on KRAS-mutated, liver-only mCRC cases as a homogeneous subgroup that may represent a relevant setting for exploring this association. MMs were identified on primary tumors. MMs were classified by mutant-specific residual transcriptional activity scores (TP53RTAS) as transcriptionally inactive (TP53inactive = TP53RTAS 0%) or active (TP53active = TP53RTAS ≥ 1%) and used for stratifying patients in progression-free survival (PFS), response rate, and overall survival (OS) analyses. The study population consisted of 62 patients. MMs were found in 39 cases (62%) with 16 having TP53inactive and 23 TP53active MMs. Patients with TP53inactive MMs showed better PFS in comparison with the remaining groups (wild-type and TP53active). This effect was retained in the multivariate model. A similar clinical impact was observed in the OS analysis. There was a significant difference in the overall response rate and rate of post-treatment resection of liver metastases between the TP53inactive and the wild-type or TP53active MMs cases. Specific TP53 MMs may identify sub-groups of patients who benefit from Bevacizumab-based systemic therapy and these findings could lead to novel tailored treatment strategies in this setting.

Novel Approach for Detection of BRAF and KRAS Mutations Using ARMS (amplification refractory mutation system) Primers for Colon Cancer Therapeutic Response Prediction

Abstract Introduction/Objective KRAS and BRAF V600E mutations are confirmed predictive biomarkers for anti-EGFR monoclonal antibody therapy response and prognosis for colorectal cancer and often considered mutually exclusive with few exceptions (0.05% of mCRC cases). We have developed a multiplex PCR assay utilizing ARMS (amplification refractory mutation system) Primers and Probes for screening and further testing of BRAF mutation status in a 2 step process. Methods/Case Report The Multiplex PCR Assay or BRAF/KRAS mutation was designed as a 5 color assay. Primers and Probes consisted of Wild Type Kras and wild and mutant (V600E/V600K) type BRAF primers and probes. For specimen, Positive and negative control standards made of engineered positive control plasmids for wild type KRAS & BRAF and mutant type V600E & V600K BRAF as well as internal control of bet actin and 2 Patient samples with known BRAF V600E mutant status were run. Mutant type V600E & V600K BRAF were mixed with wild type V600 controls in different ratios as well. Results were interpreted as BRAF wild KRAS wild/ BRAF wild KRAS mutant/ BRAF V600E KRAS wild/BRAF V600K KRAS wild type and NGS was recommended in cases of concurrent BRAF and KRAS mutations. Results (if a Case Study enter NA) Positive/negative/internal control standards for wild type KRAS & BRAF and mutant type V600E & V600K BRAF showed expected results in both CFX 96 and ABI 7500 runs in triplicates. Graphs were able to determine separate Ct values and sigmoidal amplification plots that readily differentiated KRAS wild/BRAF wild/ BRAF V600E types. Mutant type V600E & V600K BRAF that were mixed with wild type V600 controls in different ratios all showed expected results and were able to differentiate between wild and mutant types with accuracy. Also, the 2 patient samples with known (Sanger sequencing-diagnosed) V600E mutation status showed positive Ct values for KRAs wild and V600E probes and negative CT values for V600 wild/V600K probes. No invalid runs or unexpected control results were observed. Conclusion The ARMS BRAF/KRAS multiplex test is a efficient, accurate 2 step assay. In the patients and positive and negative controls prepared, it was able to reliably diagnose KRAS and BRAF mutation status in a matter of 4 hours running time. Given the fact that this is a cost effective assay that can utilize most commonly used Real time PCR machines this test may be clinically implemented if larger clinical trials utilizing tissue samples from a larger number of colon cancer patients are conducted.

A phase ib-II study of dabrafenib, trametinib, cetuximab plus irinotecan in patients with BRAF mutant metastatic colorectal cancer: Subgroup analysis and biomarker identification.

e15581 Background: About 5%-12% of patients with metastatic CRC (mCRC) have BRAF mutations in which BRAF V600E mutated was most common, accounts for approximately 90% of cases of BRAF mutation mCRC. Therefore, multi-drug combination therapy with BRAF inhibitor has been tried. The efficacy results of this study have been reported in 2023 ASCO GI (#156). The ORR was 30% (3/10), the DCR was 80% (8/10). After a median follow-up of 19.7 months, the median PFS was 7.5 months. Here, we reported the results of subsequent analyses. Methods: In this phase Ib-II trial, 15 patients with BRAF-mutant mCRC received Dabrafenib, trametinib, cetuximab plus irinotecan combination therapy. Whole exome sequencing was conducted in 8 proficient mismatch repair (pMMR) mCRC patients with BRAF V600E-mutant. Patients were followed up clinically and radiographically. Response was defined as Complete Response (CR), Partial Response (PR), Stable Disease (SD) and Progressive Disease (PD) were defined according to the response definitions of the RECIST criteria. Results: 3 mCRC patients (CR or PR) were divided into response group, 5 mCRC patients (SD or PD) were divided into non-response group. Age (59.6±4.22 vs 39.0±9.93), Gender (male 66.67% vs 80%), ECOG score (0.67 vs 0.60), ALT flare rate (66.67% vs 60%) were similar in the two group. Patients in response group have better 2-year survival rate (66.7% vs 0%, P < 0.05). Furthermore, response-related Differential Expression Genes (DEGs) (log2fc > 1, P < 0.05) were analyzed. Meanwhile, GO and KEGG pathway analysis was conducted based on DEGs. Results showed that MAPK signaling pathway related genes were down-regulated in response group such as EGF, FGF18, HGF, IGF1, MAPK10, NGF. While Apoptosis related genes were up-regulated in response group such as BCL2L1, AIFM1, DAXX. Moreover, Antigen processing and presentation related genes such as CALR, CANX, HSPA8 were enriched in response group, which indicated a more active immune microenvironment. On the contrary, Hedgehog signaling pathway related genes such as GLI1, HHIP, BOC were enriched in non-response group. Next, we verified the clinical significance of DEGS in TCGA CRC cohort database using Cox-regression analysis. Results showed that expression of IGF1, NGF, CAMK2B, CCNA1 were associated with poor prognosis and CANX, HSPA8 were associated with better prognosis, which is in accordance with our sequencing results. Conclusions: Inhibition of MAPK signaling and promoted Apoptosis was found in BRAF V600E-mutant mCRC patients who were response to Dabrafenib, trametinib, cetuximab plus irinotecan. It's worth noticing that immune activation occurred in responsive patients, indicated a potential benefit from immunotherapy combination therapy. Moreover, Hedgehog signaling pathway may be target in rescue therapy in mCRC patients. Clinical trial information: ChiCTR2200063316.

Dynamic Treatment Strategy of Chinese Medicine for Metastatic Colorectal Cancer Based on Machine Learning Algorithm.

To establish the dynamic treatment strategy of Chinese medicine (CM) for metastatic colorectal cancer (mCRC) by machine learning algorithm, in order to provide a reference for the selection of CM treatment strategies for mCRC. From the outpatient cases of mCRC in the Department of Oncology at Xiyuan Hospital, China Academy of Chinese Medical Sciences, 197 cases that met the inclusion criteria were screened. According to different CM intervention strategies, the patients were divided into 3 groups: CM treatment alone, equal emphasis on Chinese and Western medicine treatment (CM combined with local treatment of tumors, oral chemotherapy, or targeted drugs), and CM assisted Western medicine treatment (CM combined with intravenous regimen of Western medicine). The survival time of patients undergoing CM intervention was taken as the final evaluation index. Factors affecting the choice of CM intervention scheme were screened as decision variables. The dynamic CM intervention and treatment strategy for mCRC was explored based on the cost-sensitive classification learning algorithm for survival (CSCLSurv). Patients' survival was estimated using the Kaplan-Meier method, and the survival time of patients who received the model-recommended treatment plan were compared with those who received actual treatment plan. Using the survival time of patients undergoing CM intervention as the evaluation index, a dynamic CM intervention therapy strategy for mCRC was established based on CSCLSurv. Different CM intervention strategies for mCRC can be selected according to dynamic decision variables, such as gender, age, Eastern Cooperative Oncology Group score, tumor site, metastatic site, genotyping, and the stage of Western medicine treatment at the patient's first visit. The median survival time of patients who received the model-recommended treatment plan was 35 months, while those who receive the actual treatment plan was 26.0 months (P=0.06). The dynamic treatment strategy of CM, based on CSCLSurv for mCRC, plays a certain role in providing clinical hints in CM. It can be further improved in future prospective studies with larger sample sizes.

Abstract 3815: Clinical efficacy and safety of HER2 targeted therapy in patients with metastatic colorectal cancer: A systematic review and meta-analysis

Abstract Background: Therapies targeting HER2 have shown clear benefit in patients with breast or gastric cancer,; and their use in metastatic colorectal cancer (mCRC) has been increasingly explored in recent years. HER2 overexpressed or amplified (HER2-positive) mCRC is seen in 2-8% of all mCRC cases and is enriched in RAS wild-type (WT) tumors, representing a patient population that may benefit from anti-HER2 therapies. Although, several single-arm and some non-comparative randomized clinical trials have now tested the use of diverse dual anti-HER2 therapies in mCRC, no summative analysis have been performed. We conducted a systematic review and meta-analysis to evaluate the overall clinical benefit (efficacy and safety) of dual-HER2 inhibition in patients with RAS-WT HER2-positive mCRC. Methods: A systematic review of available literature was performed for clinical trials involving patients with mCRC treated with HER2 targeting therapy. Two independent reviewers selected studies and extracted data from PubMed and abstracts published at major international oncology meetings during the past 5 years. Case reports and other studies not meeting inclusion criteria were excluded, therefore a total of 13 studies were used for analysis. Patients with RAS-mutant tumors within each trial were excluded due to known limited benefit of dual HER2 inhibition in this subset. Inverse variance method with random-effects model was used for meta-analysis to determine the overall effect of the therapy on overall response rate (ORR), disease control rate (DCR), progression free survival (PFS) and treatment-related adverse events (TRAE). Results: Systematic review identified 9 study cohorts which were utilized in the meta-analysis, encompassing a total of 279 patients with mCRC who received Trastuzumab (T) in combination with either Pertuzumab (P), Tucatinib (Tu), Pyrotinib (Py), or Lapatinib (L). Collectively, dual HER2 inhibition showed an ORR of 35.1% (95% CI: 29.4-41.0%), a DCR of 68.3% (95% CI: 62.5-73.9%), and a PFS of 5.2 months (95% CI: 4.4-6.0 months). Pooled TRAE of grade ≥ 3 across studies was 29.9% (95% CI: 18.8-42.4%) but displayed high inter-study heterogeneity (p<0.0001, I2 = 79%), mainly driven by one trial (Pyro-HER2; TRAE = 75.0%, 95% CI: 50.9-91.3%). Conclusions: Overall, this comprehensive meta-analysis confirms that dual HER2 targeting therapies yield meaningful clinical efficacy, with favorable safety profiles, and improve outcomes in patients with RAS-WT HER2-positive mCRC. Citation Format: Oscar E. Villarreal, Lianchun Xiao, Joelle Allam, Alexey Sorokin, Ying Yuan, Scott Kopetz, Kanwal Pratap Raghav. Clinical efficacy and safety of HER2 targeted therapy in patients with metastatic colorectal cancer: A systematic review and meta-analysis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3815.

Biological factors driving colorectal cancer metastasis.

Approximately 20% of colorectal cancer (CRC) patients present with metastasis at diagnosis. Among Stage I-III CRC patients who undergo surgical resection, 18% typically suffer from distal metastasis within the first three years following initial treatment. The median survival duration after the diagnosis of metastatic CRC (mCRC) is only 9 mo. mCRC is traditionally considered to be an advanced stage malignancy or is thought to be caused by incomplete resection of tumor tissue, allowing cancer cells to spread from primary to distant organs; however, increasing evidence suggests that the mCRC process can begin early in tumor development. CRC patients present with high heterogeneity and diverse cancer phenotypes that are classified on the basis of molecular and morphological alterations. Different genomic and nongenomic events can induce subclone diversity, which leads to cancer and metastasis. Throughout the course of mCRC, metastatic cascades are associated with invasive cancer cell migration through the circulatory system, extravasation, distal seeding, dormancy, and reactivation, with each step requiring specific molecular functions. However, cancer cells presenting neoantigens can be recognized and eliminated by the immune system. In this review, we explain the biological factors that drive CRC metastasis, namely, genomic instability, epigenetic instability, the metastatic cascade, the cancer-immunity cycle, and external lifestyle factors. Despite remarkable progress in CRC research, the role of molecular classification in therapeutic intervention remains unclear. This review shows the driving factors of mCRC which may help in identifying potential candidate biomarkers that can improve the diagnosis and early detection of mCRC cases.

Zanzalintinib (XL092) plus atezolizumab versus regorafenib in previously treated MSS/MSI-low metastatic colorectal cancer (mCRC): The randomized phase 3 STELLAR-303 study.

TPS229 Background: Patients with microsatellite stable/microsatellite instability-low (MSS/MSI-low) mCRC account for ~95% of mCRC cases, and there is a significant unmet need in patients with treatment-refractory MSS/MSI-low mCRC. Although immune checkpoint inhibitors (ICIs) have shown limited activity in this patient population, the addition of tyrosine kinase inhibitors (TKIs) may increase sensitivity to ICIs by promoting an immune-permissive tumor microenvironment. Furthermore, TKI-ICI combinations have demonstrated encouraging clinical activity in patients with mCRC, particularly in subgroups of patients without liver metastases (LM). Most recently, in the phase 3 LEAP-017 study of patients with non–MSI-high/mismatch repair deficient (dMMR) mCRC, although pembrolizumab + lenvatinib did not improve overall survival (OS) vs standard of care, subgroup analysis suggested the potential for clinical benefit in patients without LM (Kawazoe et al, ESMO-WCGI 2023). Zanzalintinib is a novel multi-kinase inhibitor targeting VEGFR, MET, and the TAM kinases (TYRO3, AXL, MER). In a phase 1 study, zanzalintinib alone and in combination with atezolizumab (an anti–PD-L1 ICI) showed preliminary anti-tumor activity and a manageable safety profile across multiple tumor types (Sharma et al, ESMO 2022). Methods: STELLAR-303 (NCT05425940) is a global, randomized, open-label phase 3 study to assess the efficacy and safety of zanzalintinib + atezolizumab versus regorafenib in adult patients with MSS/MSI-low mCRC. Patients must have documented MSI/MMR status (non–MSI-high/dMMR) and RAS status by tissue-based analysis, measurable disease per RECIST v1.1, ECOG PS 0 or 1, and radiographic progression during/after or intolerance to standard of care treatments for mCRC. Prior regorafenib, trifluridine/tipiracil, or PD-L1/PD-1 ICIs are not allowed. Patients with or without active LM at baseline are eligible; those with definitively treated LM (includes surgical resection, microwave/radiofrequency ablation, or stereotactic body radiation therapy, but not yttrium-90 or chemoembolization alone) are considered to have non-active LM if treated ≥6 months before enrollment with no evidence of radiologic progression on subsequent imaging. Patients are randomized 1:1 to receive zanzalintinib + atezolizumab or regorafenib. Planned enrollment is 874 patients; number of patients with LM will be capped to ensure results of the study are relevant to the real-world mCRC population. Primary endpoint is OS in patients without LM. The key secondary efficacy endpoint is OS in all randomized patients. A hierarchical testing strategy will be employed for primary and key secondary endpoints. Safety will also be assessed. Enrollment is ongoing in the US, Europe, and Asia-Pacific region. Clinical trial information: NCT05425940 .

Immunocheckpoint Inhibitors in Microsatellite-Stable or Proficient Mismatch Repair Metastatic Colorectal Cancer: Are We Entering a New Era?

Colorectal cancer (CRC) is the third most frequent cancer and the second leading cause of cancer-related deaths in Europe. About 5% of metastatic CRC (mCRC) are characterized by high microsatellite instability (MSI) due to a deficient DNA mismatch repair (dMMR), and this condition has been related to a high sensitivity to immunotherapy, in particular to the Immune Checkpoint Inhibitors (ICIs). In fact, in MSI-H or dMMR mCRC, treatment with ICIs induced remarkable response rates and prolonged survival. However, the majority of mCRC cases are mismatch-repair-proficient (pMMR) and microsatellite-stable (MSS), and unfortunately these conditions involve resistance to ICIs. This review aims to provide an overview of the strategies implemented to overcome ICI resistance and/or define subgroups of patients with MSS or dMMR mCRC who may benefit from immunotherapy.

HER2 Status in RAS and BRAF Wild-Type Metastatic Colorectal Cancer: A Portuguese Study.

Colorectal cancer (CRC) is the second-most deadly cancer worldwide. However, there remains a scarcity of precision treatmentsavailable for this type of cancer. Amplification or overexpression of human epidermal growth factor receptor 2 (HER2+) is a well-established therapeutic target in gastric and breast cancer. HER2is positive in approximately 5% of CRC cases and has been implicated in resistance to therapy with anti-epidermal growth factor receptor antibodies. The aim of this study was to evaluate HER2 status in RAS and BRAF wild-type metastatic CRC (mCRC) and its correlation with survival outcomes. A single-center retrospective analysis of RAS and BRAF wild-type mCRC patients undergoing systemic treatment was conducted from July 2014 to September 2020. Tissue HER2 status was determined by immunohistochemistry (IHC) and/or fluorescence in situ hybridization (FISH) and/or chromogenic in situ hybridization (CISH). HER2+ was defined as IHC3 (+) or IHC2 (+) through FISH or CISH (+). Fifty-nine patients were included. The median age of all the included patients was 64 years (33-82). Four patients had HER2+ tumors (7%). Four patients had HER2+ tumors (7%).The majority of HER2+ mCRC cases were males (n=3) and left-sided CRC (n=3). All patients received FOLFIRI plus cetuximab as first-line treatment. At the median follow-up of 24.0 months, patients with HER2-negative mCRC presented with a median overall survival (mOS) of 39.4 months (95% confidence interval (CI) 32.7-46.0) and the four patients with HER2+ mCRC had a mOS of 20.4 months(95% CI; 9.5-31.3; p=0.07). In HER2-negative patients, themedian PFS (mPFS) was 11.3 months (95% CI; 9.2-13.4) vsHER2-positive patients with a mPFS of 10.9 months (95% CI; 1.3-20.4;p=0.47). To our knowledge, this is the first study reporting HER2+ in mCRC patients in a Portuguese population and the HER2+ rate was consistent with previous studies. Our study suggests that HER2+ may potentially be a marker that is able to predict poor prognosis in RAS and BRAF wild-type mCRC.

Abstract 1014: High tumor mutational burden in patients with mismatch repair proficient metastatic colorectal cancer: Single institution cohort

Abstract Background: High Tumor Mutational Burden (TMB) in metastatic colorectal cancer (mCRC) is mostly associated to microsatellite instability (MSS/MMRp) or alterations in POLE/POLD1 genes [1]. Tumors harboring these molecular profiles are also associated with specific clinical-pathological features well described in literature [2; 3] and treatment with immune checkpoint inhibitors (ICI) represent the therapy with the highest expected benefit [4; 5; 6; 7; 8]. This subgroup of population represents almost 5% of the entire population of mCRC patients (pts) [9; 10]. About the remaining 95% of the population, for which immunotherapy doesn’t seem to improve outcome [4; 10; 11; 12], we know that a subgroup of pts reported high TMB, not related to MSS/MMRp or mutation in Polymerase genes [1]. For this subgroup data are scarce in the literature. Methods: We selected a case series of MSS/MMRp, non-POLE/POLD1 mCRC cases with documented TMB >= 10mut/Mb at comprehensive genomic profiling tested with Foundation Medicine panel between January 2019 and June 2022. Clinical-pathological features were collected from clinical reports and evaluated with descriptive statistics. Two pathologists reviewed the slides to assess histopathological features. Results: 24 out of 693 (3.5%) pts had MSS/MMRp, non-POLE/POLD1 mCRC with TMB >= 10 Mut/Mb. Average TMB was 19.04 mut/Mb (10 - 104.65 mut/Mb). 56% were male; median age at mCRC diagnosis was 58 years old (IQR 48-64 yo). 16 pts had left-side primary tumor, 6 of which had rectal cancer. 14 had synchronous metastases and the most frequent stage parameters were T3/4 and N+. The following histotypes were documented: 18/24 were adenocarcinoma NOS, 3/24 mucinous, 1/24 of cribriform comedonecrosis type, 1/24 a mixed neuroendocrine-non-neuroendocrine neoplasm (MiNen) and 1/24 not assessable. With regard to grading, 12/24 high-grade cases and 11/24 low-grade cases, 1 case not assessable. 7/18 assessable cases had high tumor infiltrating lymphocytes (TILs) (>=2.0 TILs/HPF) and 18/18 assessable cases showed signs of lympho-vascular invasion. According to comprehensive molecular profiling, the 5 most frequent genes altered were APC (80.0%), TP53 (72.0%), KRAS (24.0%), SMAD2/4 (24.0%), PIK3CA (24.0%). 3 pts had BRAF V600E mutations. In our case study, 23 out of 24 pts started 1st line treatment for metastatic disease, of which 21 with poli-chemo schedules. Data about best response were available for 21 cases and ORR was 61.9%, DCR 90.4%. Median PFS was 13.6 months (IQR 5.6 - 25.9). Median OS was 47.2 months (IQR 25.7 - 63.3). Conclusion: MSS/MMRp, non-POLE/POLD1, TMB >= 10 mut/Mb is a small but defined subgroup of mCRCs. To better understand the molecular behavior of this rare subgroup of cancers, further study should investigate the underlying mechanism, the TMB cut-off relevance in mCRC and the potential predictive impact on immunotherapy efficacy. Citation Format: Giulia Maddalena, Valentina Angerilli, Gianmarco Ricagno, Aldo Montagna, Riccardo Cerantola, Giada Munari, Sara Lonardi, Francesca Bergamo, Matteo Fassan. High tumor mutational burden in patients with mismatch repair proficient metastatic colorectal cancer: Single institution cohort [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1014.

BRAF V600E and RNF43 Co-mutations Predict Patient Outcomes With Targeted Therapies in Real-World Cases of Colorectal Cancer.

Anti-BRAF/EGFR therapy is approved for metastatic colorectal cancer (mCRC) with BRAFV600E mutations, although not all patients respond. Novel recent findings indicate the potential of RNF43 mutations to predict outcomes in patients with BRAF-mutated microsatellite stable (MSS) mCRC treated with anti-BRAF/EGFR therapy. This study aimed to independently and rapidly validate BRAFV600E/RNF43 co-mutations as predictive biomarkers of benefit to anti-EGFR/BRAF therapy. Clinical data were derived from electronic health record data from ~280 US cancer clinics between January 2011 and March 2022 from the Flatiron Health-Foundation Medicine real-world clinico-genomic mCRC database. Real-world cases of BRAFV600E-mutated mCRC, with patients receiving anti-BRAF/EGFR therapy (n = 49), were included. Patients who were MSS, with RNF43 mutations, had favorable progression-free survival (hazard ratio [HR] 0.29; 95% CI [CI], 0.13-0.65) and overall survival (HR 0.32, 95% CI, 0.12-0.84) compared with wild type. No difference in outcomes was observed between patient groups with RNF43-mutant versus wild-type receiving standard-of-care chemotherapy. BRAFV600E/RNF43 co-mutations predict mCRC anti-BRAF/EGFR outcomes in diverse clinical settings.

Comparative analysis of tumor immune microenvironment in primary tumors vs metastatic tissue in microsatellite stable metastatic colorectal cancer.

187 Background: We previously demonstrated differences in responses to checkpoint inhibitors between liver and non-liver metastases (mets) in microsatellite stable (MSS) metastatic colorectal cancer (mCRC). Here, we investigate differences in tumor microenvironment (TME) and mutational landscape of primary and mCRC sites. Methods: We used the Tempus clinicogenomic database to select de-identified cases of MSS mCRC which underwent Tempus xT testing. Tempus xT is a 648-gene NGS panel that detects somatic alterations and includes RNA sequencing. Gene expression patterns of different immune cells were used to predict their relative abundance within the tumor. Analyzed tumors were divided into 4 categories based: primary tumor (colon), liver, lung, and peritoneal mets. Demographics, genomic alterations, tumor mutational burden (TMB), PD-L1 expression, and proportions of B, T (CD4+, CD8+), NK cells, and macrophages were compared between all 4 categories. Chi-squared/Fisher’s exact tests or Kruskal-Wallis tests were used to assess statistical significance. Results: Genomic profiles from 4,345 unique mCRC patients were analyzed (Primary CRC = 1734; Liver = 1825; Lung = 443; Peritoneal = 343). Median TMB and PD-L1 expressions had small differences across sites that were statistically significant. KRAS mutations were more frequent and SMAD4 mutations were less prevalent in lung mets. RNA-Seq revealed significant differences in immune cell composition. Lung mets exhibited a higher percentage of B cells and lower percentage of macrophages than liver and peritoneum (p< 0.001), similar to primary tumors. CD4+ T cells were highest in primary tumors, whereas CD8+ T cells were highest in lung mets (p < 0.001). Conclusions: The TME of lung mets has a more favorable immune composition (increased CD8+ T cells and B cells, decreased macrophages) than that of liver and peritoneal mets, suggesting that MSS mCRC to the lung may potentially be more responsive to immunotherapy.[Table: see text]

Current Landscape and Potential Challenges of Immune Checkpoint Inhibitors in Microsatellite Stable Metastatic Colorectal Carcinoma.

Colorectal cancer (CRC) is the third most frequent cancer and the second most common cause of cancer-related death in Europe. High microsatellite instability (MSI-H) due to a deficient DNA mismatch repair (dMMR) system can be found in 5% of metastatic CRC (mCRC) and has been established as a biomarker of response to immunotherapy in these tumors. Therefore, immune checkpoint inhibitors (ICIs) in mCRC with these characteristics were evaluated with results showing remarkable response rates and durations of response. The majority of mCRC cases have high levels of DNA mismatch repair proteins (pMMR) with consequent microsatellite stability or low instability (MSS or MSI-low), associated with an inherent resistance to ICIs. This review aims to provide a comprehensive analysis of the possible approaches to overcome the mechanisms of resistance and evaluates potential biomarkers to establish the role of ICIs in pMMR/MSS/MSI-L (MSS) mCRC.

Real-world first-line treatment of patients with BRAFV600E-mutant metastatic colorectal cancer: the CAPSTAN CRC study

BRAFV600E mutations occur in 8%-12% of metastatic colorectal cancer (mCRC) cases and are associated with poor survival. European guidelines recommend combination (doublet or triplet) chemotherapy plus bevacizumab in first line. However, an unmet need remains for more effective treatments for these patients. CAPSTAN CRC is a European, retrospective, multicenter, observational study evaluating real-world treatment practices for patients with BRAFV600E-mutant mCRC treated between 1 January 2016 and 31 January 2020. The primary objective was to describe first-line treatment patterns. Secondary objectives included describing baseline demographics, mutational testing procedures, treatment effectiveness, and safety. In total, 255 patients (median age 66.0 years; 58.4% female) with BRAFV600E-mutant unresectable mCRC from seven countries were included. Most had right-sided tumors (52.5%) and presented with synchronous disease at diagnosis (66.4%). Chemotherapy plus targeted therapy (68.7%) was preferred at first line over chemotherapy alone (31.3%). The main first-line treatments were FOLFOX plus bevacizumab (27.1%) and FOLFOXIRI (folinic acid, 5-fluorouracil, oxaliplatin, irinotecan) with/without bevacizumab (27.1%/19.2%). Median duration of first-line treatment was 4.9 months. Overall, 52.5% received second-line treatment. Across all first-line regimens, progression-free survival (PFS) and overall survival were 6.0 [95% confidence interval (CI) 5.3-6.7] months and 12.9 (95% CI 11.6-14.1) months, respectively. Triplet plus targeted therapy was associated with more adverse events (75.0%) compared with triplet chemotherapy alone (50.0%) and doublet chemotherapy alone (36.1%). Multivariate analysis identified low body mass index and presence of three or more metastatic sites as significant prognostic factors for PFS. This study is, to date, the largest real-world analysis of patients with BRAFV600E-mutant mCRC, providing valuable insights into routine first-line treatment practices for these patients. The data highlight the intrinsic aggressiveness of this disease subgroup, confirming results from previous real-world studies and clinical trials, and stressing the urgent need for more effective treatment options in this setting.

Cabozantinib sensitizes microsatellite stable colorectal cancer to immune checkpoint blockade by immune modulation in human immune system mouse models.

Immune checkpoint inhibitors have been found to be effective in metastatic MSI-high colorectal cancers (CRC), however, have no efficacy in microsatellite stable (MSS) cancers, which comprise the majority of mCRC cases. Cabozantinib is a small molecule multi-tyrosine kinase inhibitor that is FDA approved in advanced renal cell, medullary thyroid, and hepatocellular carcinoma. Using Human Immune System (HIS) mice, we tested the ability of cabozantinib to prime MSS-CRC tumors to enhance the potency of immune checkpoint inhibitor nivolumab. In four independent experiments, we implanted distinct MSS-CRC patient-derived xenografts (PDXs) into the flanks of humanized BALB/c-Rag2nullIl2rγnullSirpαNOD (BRGS) mice that had been engrafted with human hematopoietic stem cells at birth. For each PDX, HIS-mice cohorts were treated with vehicle, nivolumab, cabozantinib, or the combination. In three out of the four models, the combination had a lower tumor growth rate compared to vehicle or nivolumab-treated groups. Furthermore, interrogation of the HIS in immune organs and tumors by flow cytometry revealed increased Granzyme B+, TNFα+ and IFNγ+ CD4+ T cells among the human tumor infiltrating leukocytes (TIL) that correlated with reduced tumor growth in the combination-treated HIS-mice. Notably, slower growth correlated with increased expression of the CD4+ T cell ligand, HLA-DR, on the tumor cells themselves. Finally, the cabozantinib/nivolumab combination was tested in comparison to cobimetinib/atezolizumab. Although both combinations showed tumor growth inhibition, cabozantinib/nivolumab had enhanced cytotoxic IFNγ and TNFα+ T cells. This pre-clinical in vivo data warrants testing the combination in clinical trials for patients with MSS-CRC.

Emerging Role of ERBB2 in Targeted Therapy for Metastatic Colorectal Cancer: Signaling Pathways to Therapeutic Strategies.

Simple SummaryColorectal cancer (CRC) is the third most commonly diagnosed malignancy and the second most common cause of cancer-related mortality worldwide. Currently available targeted therapies for metastatic CRC mainly target vascular endothelial growth factor and epidermal growth factor receptor in RAS wild-type tumors. Although Erb-B2 receptor tyrosine kinase 2 (ERBB2/human epidermal growth factor receptor 2) plays a significant therapeutic role in breast and gastric cancers, there are no licensed ERBB2-targeted therapies for metastatic CRC. This review aims to outline the molecular biology of ERBB2-positive metastatic CRC and potential targeted therapeutic strategies.Despite recent improvements in the comprehensive therapy of malignancy, metastatic colorectal cancer (mCRC) continues to have a poor prognosis. Notably, 5% of mCRC cases harbor Erb-B2 receptor tyrosine kinase 2 (ERBB2) alterations. ERBB2, commonly referred to as human epidermal growth factor receptor 2, is a member of the human epidermal growth factor receptor family of protein tyrosine kinases. In addition to being a recognized therapeutic target in the treatment of gastric and breast malignancies, it is considered crucial in the management of CRC. In this review, we describe the molecular biology of ERBB2 from the perspective of biomarkers for mCRC-targeted therapy, including receptor structures, signaling pathways, gene alterations, and their detection methods. We also discuss the relationship between ERBB2 aberrations and the underlying mechanisms of resistance to anti-EGFR therapy and immunotherapy tolerance in these patients with a focus on novel targeted therapeutics and ongoing clinical trials. This may aid the development of a new standard of care in patients with ERBB2-positive mCRC.

P41-7 Two cases of BRAF mutant mCRC with intestinal stenosis responded to encorafenib + binimetinib + cetuximab: A case report

BRAF mutant metastatic Colorectal Cancer (mCRC) has a poor prognosis and response to chemotherapy. The oral agents, encorafenib and binimetinib in combination with cetuximab (BEACON-3) was approved as 2nd-line therapy for BRAF mutant mCRC in Japan. However, we often experience mCRC patients with intestinal stenosis. These patients may not be eligible for oral medication due to decline of drug absorption. We report two cases of BRAF mutant mCRC that developed intestinal stenosis during 1st-line therapy and responded to BEACON-3.

Tumor calcification is associated with better survival in metastatic colorectal cancer patients treated with bevacizumab plus chemotherapy.

Aims: The purpose was to investigate the correlation between calcification and outcome in metastatic colorectal cancer (mCRC) patients who received bevacizumab plus chemotherapy as the first-line treatment. Methods: A single retrospective cohort study was conducted with all diagnosed mCRC cases who received bevacizumab and chemotherapy as the first-line therapy. Results: Among all enrolled patients (n=159), 31 had tumor calcification. The median overall survival and progression-free survival were significantly better in patients with tumor calcification than in those without calcification. A higher objective overall response rate was also observed in the tumor calcification group. On multivariate analysis, tumor calcification was independently associated with overall survival and progression-free survival. Conclusions: Tumor calcification was independently associated with improved survival in mCRC patients treated with bevacizumab plus chemotherapy.

Comprehensive genomic profiling in advanced/metastatic colorectal cancer: number needed to test and budget impact of expanded first line use

Aims Use of comprehensive genomic profiling (CGP) in metastatic colorectal cancer (mCRC) is limited. We estimated impacts of expanded 1 L CGP, using the Tempus xT test, on detection of actionable alterations and testing budgets in a modeled US health plan over two-years. Materials and methods A decision analytic model was developed to estimate the impact of replacing 20% of usual testing (a mix of CGP and non-CGP) with Tempus xT CGP. Actionable alterations for matched treatments or clinical trial included KRAS, NRAS, RAF, BRAF, deficient mismatch repair (dMMR)/microsatellite instability (MSI), NTRK, RET, EGFR, HER2, MET, PIK3CA and POLE1. Costs included initial and repeat testing, physician-associated and administrative costs. Results In a hypothetical five-million-member plan, 50% Medicare and 50% commercial, 1,112 new cases of mCRC were expected per year. Of these, 566 (51%) would undergo 1 L molecular testing, with 55 re-tested upon progression. Based on current testing rates, there were an expected 521 missed opportunities for genomically informed treatment (47% of new cases), with 442 missed due to lack of testing and 79 due to testing without CGP. Replacing 20% of usual testing with Tempus xT CGP was associated with up to a $0.003 per member per month testing cost increase (net total cost of $202,102 for the five-million-member plan) and 15.5 additional patients with an opportunity for genomically informed care (12.7 patients for treatment and 2.8 for clinical trial). The testing total cost (initial test, repeat test, biopsy and physician services, and administrative cost) to put one additional patient with mCRC on matched therapy or matched clinical trial was estimated to be $13,005. Number needed to test to identify one actionable alteration with Tempus xT CGP versus usual testing was 7.8 patients. Limitations Conservative assumptions were made for inputs with limited evidence. Based on high concordance rates with dMMR/MSI status, tumor mutational burden (TMB) status was not calculated separately. Conclusions Replacing 20% of usual testing with Tempus xT CGP was associated with a small incremental testing cost and can identify meaningfully more actionable alterations.

Risk factors for venous thromboembolism in metastatic colorectal cancer with contemporary treatment: A SEER-Medicare analysis.

BackgroundThe relationship between metastatic colorectal cancer (mCRC) and venous thromboembolism (VTE) is poorly defined in the modern era. Our objective was to examine impact of putative risk factors including newer treatments and anti‐angiogenic therapy on VTE incidence and survival in a modern older mCRC cohort.MethodsThis is a SEER‐Medicare cohort analysis of mCRC patients diagnosed in 2004–2009. Risk factor analysis was conducted using Cox models adjusted for sex, diagnosis age, race, primary tumor location, comorbidity, and prior VTE history, with cancer treatments as time‐varying covariates. Main outcomes were VTE incidence and overall survival.ResultsTen thousand nine hundred and seventy six mCRC cases with mean age 77.9 years (range 65–107), 49.7% women, 83.5% white. There were 1306 VTE cases corresponding to 13.7% incidence at 1 year and 20.3% at 3 years. Independent VTE predictors included female sex (HR 1.27; 95% CI 1.14–1.42), African American race (HR 1.49; 1.27–1.73), prior VTE history (HR 16.3; 12.1–22.1), and right sided cancers (HR 1.16; 1.04–1.29). After adjustment, any therapy and bevacizumab (HR 0.68, 0.58–0.78) in particular were protective. Overall survival was 40.1% (39.4–41.3) at 1 year but improved significantly with any treatment. VTE following diagnosis of mCRC was associated with inferior OS (HR 1.09; 1.02–1.15).ConclusionsIn this large contemporary mCRC cohort, effective systemic therapy including anti‐angiogenic treatment was associated with lower VTE risk. Overall survival was poor, and modestly worse if a patient had a VTE at any time during treatment.