Cetuximab rechallenge in metastatic colorectal cancer patients: how to come away from acquired resistance?

MiR-135b-5p promotes cetuximab resistance in colorectal cancer by regulating FOXN3

Despite advances in targeted therapies, primary and acquired resistance make the treatment of colorectal cancer (CRC) a pressing issue to be resolved. According to reports, the development of CRC is linked to miRNA dysregulation. Multiple studies have demonstrated that miR-135b-5p has an aberrant expression level between CRC tissues and adjacent tissues. However, it is unclear whether there is a correlation between miR-135b-5p and cetuximab (CTx) resistance in CRC. Use the GEO database to measure miR-135b-5p expression in CRC. Additionally, RT-qPCR was applied to ascertain the production level of miR-135b-5p in three human CRC cells and NCM460 cells. The capacity of cells to migrate and invade was examined utilizing the wound-healing and transwell assays, while the CCK-8 assay served for evaluating cell viability, as well as colony formation assays for proliferation. The expected target protein of miR-135b-5p in CRC cell cetuximab resistance has been investigated using western blot. Suppression of miR-135b-5p could increase the CTx sensitivity of CTx-resistant CRC cells, as manifested by the attenuation of proliferation, migration, and invasion ability. Mechanistic studies revealed miR-135b-5p regulates the epithelial-to-mesenchymal transition (EMT) process and Wnt/β-catenin signaling pathway through downgulating FOXN3. In short, knockdowning miR-135b-5p could increase FOXN3 expression in CRC cells, promote the EMT process, and simultaneously activate the Wnt/β-catenin signaling pathway to elevate CTx resistance in CRC cells.

Efficacy of anti-epidermal growth factor antibody rechallenge in RAS/BRAF wild-type metastatic colorectal cancer: a multi-institutional observational study

PURPOSE

To investigate circulating tumor DNA (ctDNA) RAS mutant (MT) incidence before salvage-line treatment and the clinicopathological features and molecular biological factors associated with the efficacy of anti-epithelial growth factor receptor (EGFR) monoclonal antibody (mAb) rechallenge for tissue RAS/BRAF wild type (WT) metastatic colorectal cancer (mCRC).

METHODS

This multi-institutional retrospective observational study included 74 patients with mCRC with tissue RAS/BRAF WT refractory to first-line chemotherapy containing anti-EGFR mAb. ctDNA RAS status was assessed using the OncoBEAM™ RAS CRC Kit. We explored the clinicopathological features associated with ctDNA RAS status and the factors related to anti-EGFR mAb rechallenge efficacy in multivariate Cox proportional hazard regression.

RESULTS

The incidence of RAS MT in ctDNA was 40.5% (30/74), which was associated with primary tumor resection (P = 0.016), liver metastasis (P < 0.001), and high tumor marker levels (P < 0.001). Among the 39 patients treated with anti-EGFR mAb rechallenge, those with ctDNA RAS WT showed significantly longer progression-free survival (PFS) than those with ctDNA RAS MT (median 4.1 vs. 2.7 months, hazard ratio [HR] = 0.39, P = 0.045). Patients who responded to first-line anti-EGFR mAb showed significantly longer PFS (HR = 0.21, P = 0.0026) and overall survival (OS) (HR = 0.23, P = 0.026) than those with stable disease.

CONCLUSIONS

The incidence of ctDNA RAS MT mCRC was 40.5%, which was associated with liver metastases and high tumor volumes. Anti-EGFR mAb rechallenge may be effective for patients with mCRC who responded to first-line chemotherapy containing anti-EGFR mAb. No patients with RAS MT in ctDNA responded to anti-EGFR mAb rechallenge.

Rechallenge with Anti-EGFR Treatment in RAS/BRAF wt Metastatic Colorectal Cancer (mCRC) in Real Clinical Practice: Experience of the GITuD Group

BACKGROUND

There are few third- and fourth-line therapeutic options for metastatic colorectal cancer (mCRC). In RAS/BRAF wild-type (wt) mCRC previously treated with anti-epidermal growth factor receptor (anti-EGFR) (first-line) and relapsed after a good response, retreatment with anti-EGFR (rechallenge) emerges as a therapeutic alternative.

OBJECTIVE

The aim was to show the activity and safety of anti-EGFR rechallenge in RAS/BRAF wt mCRC in real-world practice.

PATIENTS AND METHODS

A multicenter, retrospective, observational study (six hospitals of the Galician Group of Research in Digestive Tumors) was conducted. Adult patients with RAS/BRAF wt mCRC, evaluated by liquid biopsy, were included. They received anti-EGFR rechallenge (cetuximab, panitumumab) as monotherapy, or combined with chemotherapy, in third- or subsequent lines. Efficacy (overall response rate [ORR], disease control rate [DCR], overall survival [OS], and progression-free survival [PFS]) and safety (incidence of adverse events [AEs]) were assessed.

RESULTS

Thirty-one patients were analyzed. Rechallenge (median 6 cycles [range 1-27], mainly cetuximab [80.7%]), started at a median anti-EGFR-free time of 18.4 months (1.7-37.5 months) after two (38.7%) or more (61.3%) lines of treatment; 64.5% of patients received a full dose. Median OS and PFS were 9.8 months (95% confidence interval [CI] 8.2-11.4) and 2.6 months (95% CI 1.7-3.4), respectively. ORR was 10%, and DCR was 30%. The most common AEs were diarrhea (35.5%), anemia (29%), emesis (6.4%), and neutropenia (6.4%); < 5% grade ≥ 3; 48.4% of patients reported anti-EGFR-related skin toxicity (grade > 1). Hypomagnesemia required supplements in 29% of patients. Dose delays (≥ 3 days) and reduction (≥ 20%) were reported in 11 (35.5%) and seven patients (22.6%), respectively.

CONCLUSIONS

In RAS/BRAF wt mCRC patients, an anti-EGFR rechallenge provides a feasible therapeutic option with clinical benefit (survival) and a manageable safety profile.

Therapeutic strategies targeting the epidermal growth factor receptor signaling pathway in metastatic colorectal cancer

More than 1.9 million new colorectal cancer (CRC) cases and 935000 deaths were estimated to occur worldwide in 2020, representing about one in ten cancer cases and deaths. Overall, colorectal ranks third in incidence, but second in mortality. More than half of the patients are in advanced stages at diagnosis. Treatment options are complex because of the heterogeneity of the patient population, including different molecular subtypes. Treatments have included conventional fluorouracil-based chemotherapy, targeted therapy, immunotherapy, etc. In recent years, with the development of genetic testing technology, more and more targeted drugs have been applied to the treatment of CRC, which has further prolonged the survival of metastatic CRC patients.

BRAF/MEK inhibitor rechallenge in advanced melanoma patients

BACKGROUND

Effectivity of BRAF(/MEK) inhibitor rechallenge has been described in prior studies. However, structured data are largely lacking.

METHODS

Data from all advanced melanoma patients treated with BRAFi(/MEKi) rechallenge were retrieved from the Dutch Melanoma Treatment Registry. The authors analyzed objective response rate (ORR), progression-free survival (PFS), and overall survival (OS) for both first treatment and rechallenge. They performed a multivariable logistic regression and a multivariable Cox proportional hazards model to assess factors associated with response and survival.

RESULTS

The authors included 468 patients in the largest cohort to date who underwent at least two treatment episodes of BRAFi(/MEKi). Following rechallenge, ORR was 43%, median PFS was 4.6 months (95% confidence interval [CI], 4.1-5.2), and median OS was 8.2 months (95% CI, 7.2-9.4). Median PFS after rechallenge for patients who discontinued first BRAFi(/MEKi) treatment due to progression was 3.1 months (95% CI, 2.7-4.0) versus 5.2 months (95% CI, 4.5-5.9) for patients who discontinued treatment for other reasons. Discontinuing first treatment due to progression and lactate dehydrogenase (LDH) levels greater than two times the upper limit of normal were associated with lower odds of response and worse PFS and OS. Symptomatic brain metastases were associated with worse survival, whereas a longer treatment interval between first treatment and rechallenge was associated with better survival. Responding to the first BRAFi(/MEKi) treatment was not associated with response or survival.

CONCLUSIONS

This study confirms that patients benefit from rechallenge. Elevated LDH levels, symptomatic brain metastases, and discontinuing first BRAFi(/MEKi) treatment due to progression are associated with less benefit from rechallenge. A prolonged treatment interval is associated with more benefit from rechallenge.

Unveiling acquired resistance to anti-EGFR therapies in colorectal cancer: a long and winding road

Emergence of acquired resistance limits the efficacy of the anti-EGFR therapies cetuximab and panitumumab in metastatic colorectal cancer. In the last decade, preclinical and clinical cohort studies have uncovered genomic alterations that confer a selective advantage to tumor cells under EGFR blockade, mainly downstream re-activation of RAS-MEK signaling and mutations in the extracellular domain of EGFR (EGFR-ECD). Liquid biopsies (genotyping of ctDNA) have been established as an excellent tool to easily monitor the dynamics of genomic alterations resistance in the blood of patients and to select patients for rechallenge with anti-EGFR therapies. Accordingly, several clinical trials have shown clinical benefit of rechallenge with anti-EGFR therapy in genomically-selected patients using ctDNA. However, alternative mechanisms underpinning resistance beyond genomics -mainly related to the tumor microenvironment-have been unveiled, specifically relevant in patients receiving chemotherapy-based multi-drug treatment in first line. This review explores the complexity of the multifaceted mechanisms that mediate secondary resistance to anti-EGFR therapies and potential therapeutic strategies to circumvent acquired resistance.

Clinical outcomes of intermittent panitumumab based-therapy for previously treated older patient with metastatic colorectal cancer: a case report and review of literature

Background

Metastatic colorectal cancer is one of the most common causes of cancer death worldwide, and its incidence increases with age. Treating an older RAS and BRAF wild-type patient represents a challenge for the medical oncologist, even more so for those patients defined as "vulnerable" and undergoing at least two lines of therapy. In this context, recent evidence supports the role of retreatment with anti-EGFR inhibitors and the use of liquid biopsy. However, frequent skin toxicity constitutes a limitation of therapy, especially in older people. Since it has been described that continuous administration of these monoclonal antibodies leads to acquired resistance to anti-EGFRs, with consequent therapeutic failure, an intermittent strategy with chemotherapy plus an anti-EGFR could help maintain the efficacy of the treatment over time, delaying the resistance and improving patients' quality of life.

Case presentation

In this case report, we describe the case of an older RAS and BRAF wild-type patient reporting a clinical response after first-line chemotherapy with FOLFOX + panitumumab, subsequently interrupted in the absence of disease progression. After radiological worsening and two additional lines of therapy, the reintroduction of panitumumab plus 5-fluorouracil, administered with a stop-and-go strategy, allowed the patient to benefit from the same drugs for 2 years from diagnosis, to achieve a clinical response during fourth-line treatment lasting more than 3 years, to delay resistance and to avoid unacceptable anti-EGFR skin toxicity. This patient, who died from a myocardial infarction more than 5 years after diagnosis, represents the case of a good synergy between molecular profile of disease and reintroduction of an anti-EGFR with intermittent strategy.

Anti-EGFR Rechallenge in Patients With Refractory ctDNA RAS/BRAF wt Metastatic Colorectal Cancer: A Nonrandomized Controlled Trial

Importance

The available evidence regarding anti-epidermal growth factor receptor (EGFR) inhibitor rechallenge in patients with refractory circulating tumor DNA (ctDNA) RAS/BRAF wild-type (wt) metastatic colorectal cancer (mCRC) is derived from small retrospective and prospective studies.

Objective

To evaluate the efficacy of anti-EGFR rechallenge in patients with refractory ctDNA RAS/BRAF wt mCRC.

Design, Setting, and Participants

This nonrandomized controlled trial used a pooled analysis of individual patient data from patients with RAS/BRAF wt ctDNA mCRC enrolled in 4 Italian trials (CAVE, VELO, CRICKET, and CHRONOS) and treated with anti-EGFR rechallenge between 2015 and 2022 (median [IQR] follow-up, 28.1 [25.8-35.0] months).

Intervention

Patients received anti-EGFR rechallenge therapy, including cetuximab plus avelumab, trifluridine-tipiracil plus panitumumab, irinotecan plus cetuximab, or panitumumab monotherapy.

Main Outcomes and Measures

Overall survival (OS), progression-free survival (PFS), overall response rate (ORR), and disease control rate (DCR) were calculated. Exploratory subgroup analysis evaluating several clinical variables was performed. Safety was reported.

Results

Overall, 114 patients with RAS/BRAF wt ctDNA mCRC (median [IQR] age, 61 [29-88] years; 66 men [57.9%]) who received anti-EGFR rechallenge as experimental therapy (48 received cetuximab plus avelumab, 26 received trifluridine-tipiracil plus panitumumab, 13 received irinotecan plus cetuximab, and 27 received panitumumab monotherapy) were included in the current analysis. Eighty-three patients (72.8%) had received 2 previous lines of therapy, and 31 patients (27.2%) had received 3 or more previous lines of therapy. The ORR was 17.5% (20 patients), and the DCR was 72.3% (82 patients). The median PFS was 4.0 months (95% CI, 3.2-4.7 months), and the median OS was 13.1 months (95% CI, 9.5-16.7 months). The subgroup of patients without liver involvement had better clinical outcomes. The median PFS was 5.7 months (95% CI, 4.8-6.7 months) in patients without liver metastasis compared with 3.6 months (95% CI, 3.3-3.9 months) in patients with liver metastasis (hazard ratio, 0.56; 95% CI, 0.37-0.83; P = .004). The median OS was 17.7 months (95% CI, 13-22.4 months) in patients without liver metastasis compared with 11.5 months (95% CI, 9.3-13.9 months) in patients with liver metastasis (hazard ratio, 0.63; 95% CI, 0.41-0.97; P = .04). Treatments showed manageable toxic effects.

Conclusions and Relevance

These findings suggest that anti-EGFR rechallenge therapy has promising antitumor activity in patients with refractory ctDNA RAS/BRAF wt mCRC. Within the limitation of a subgroup analysis, the absence of liver metastases was associated with significant improved survival.

Trial Registration

ClinicalTrials.gov Identifiers: NCT02296203; NCT04561336; NCT03227926; NCT05468892.

Chemotherapy re-use versus anti-angiogenic monotherapy as the third-line treatment of patients with metastatic colorectal cancer: a real-world cohort study

BACKGROUND

There are various recommendations for third-line treatment in mCRC, however, there is no consensus on who is more suitable for particular strategy. Chemotherapy re-use in third-line setting is a common option in clinical practice. This study aimed to investigate the efficacy of third-line chemotherapy re-use by the comparison with that of anti-angiogenic monotherapy, and further find the population more suitable for third-line chemotherapy.

METHODS

Using electronic medical records of patients with mCRC, a retrospective cohort study was conducted. A total of 143 patients receiving chemotherapy and 40 patients receiving anti-angiogenic monotherapy in third-line setting as control group were retrospectively collected. Baseline characteristics were analyzed using the χ² test or the Fisher's exact test. ROC curve and surv_cutpoint function of 'survminer' package in R software were used to calculate the cut-off value. Survival curves were plotted with the Kaplan-Meier method and were compared using the log-rank test. The Cox proportional hazard regression model was used to analyze the potential risk factors.

RESULTS

A total of 143 patients receiving chemotherapy and 40 patients receiving anti-angiogenic monotherapy in third-line setting were retrospectively collected. Chemotherapy rechallenge was recorded in 93 patients (93/143, 65.0%), and the remaining patients chose new chemotherapeutic drugs that had not been previously used, including irinotecan-based (22/50), oxaliplatin-based (9/50), raltitrexed (9/50), gemcitabine (5/50) and other agents (5/50). The ORR and DCR of third-line chemotherapy reached 8.8%, 61.3%, respectively (anti-angiogenic monotherapy group: ORR 2.6%, DCR 47.4%). The mPFS and mOS of patients receiving chemotherapy were 4.9 and 12.0 m, respectively (anti-angiogenic monotherapy group: mPFS 2.7 m, mOS 5.2 m). Subgroup analyses found that patients with RAS/RAF mutation, longer PFS (greater than 10.6 m) in front-line treatment or larger tumor burden had better prognosis with third-line chemotherapy rather than anti-angiogenic monotherapy.

CONCLUSIONS

Third-line chemotherapy re-use was effective in mCRC. Those with more aggressive characteristics (RAS/RAF mutant, larger tumor burden) or better efficacy of previous chemotherapy (longer PFS) were more appropriate for third-line chemotherapy, rather than anti-angiogenic monotherapy.

The role of anti-EGFR rechallenge in metastatic colorectal cancer, from available data to future developments: A systematic review

Despite recent molecular and immunological advancements, prognosis of metastatic colorectal cancer (mCRC) patients remains poor. In this context, several retrospective and phase II studies suggested that after failure of an upfront anti-EGFR based regimen, a subset of patients can still benefit from further anti-EGFR blockade. Several translational studies involving circulating tumor DNA (ctDNA) analysis demonstrated that cancer clones harboring mutations driving anti-EGFR resistance, which can arise under anti-EGFR agents selective pressure, often decay after anti-EGFR discontinuation potentially restoring sensitivity to this therapeutic strategy. Accordingly, several retrospective analyses and a recent prospective trial demonstrated that ctDNA RAS and BRAF wild-type mCRC patients are those benefitting the most from anti-EGFR rechallenge. Indeed, in molecularly selected patients, anti-EGFR rechallenge strategy achieved up to 30 % response rate, with a progression free survival longer than 4 months and an overall survival longer than 1 year, which favorably compared with other standard therapeutic options available for heavily pretreated patients. Anti-EGFR is also well tolerated with no unexpected toxicities compared to the upfront setting. However, several open questions remain to be addressed towards a broader applicability of anti-EGFR strategy in the everyday clinical practice such as the identification of the best rechallenge regimen, the right placement in mCRC therapeutic algorithm, the best ctDNA screening panel. In our systematic review, we revised available data from clinical trials assessing anti-EGFR rechallenge activity in chemo-refractory mCRC patients, discussing as well potential future scenarios and development to implement this therapeutic approach. Particularly, we discussed the role of ctDNA as a safe, timely and comprehensive tool to refine patient's selection and the therapeutic index of anti-EGFR rechallenge.

Efficacy of Chemotherapy Rechallenge Versus Regorafenib or Trifluridine/Tipiracil in Third-Line Setting of Metastatic Colorectal Cancer: A Multicenter Retrospective Comparative Study

PURPOSE

Metastatic colorectal cancer (mCRC) is a significant global health burden. This retrospective study compared the effectiveness of trifluridine/tipiracil (FTD/TPI), regorafenib, and chemotherapy rechallenge for third-line mCRC treatment.

MATERIALS AND METHODS

We reviewed the medical records of 132 patients with mCRC treated with regorafenib, FTD/TPI, or a rechallenge with the initial chemotherapy regimen in a third-line setting from four different institutions. The primary end point was progression-free survival (PFS). Secondary end points were objective response rate and overall survival (OS) across the three treatment approaches.

RESULTS

Twenty-nine patients received chemotherapy rechallenge, and 103 received FTD/TPI or regorafenib. Patients' characteristics were comparable, except for a lower number of left-sided primaries and KRAS wild-type tumors in the FTD/TPI-regorafenib group. The median PFS for the entire group was 3.0 months, and the median OS was 13.7 months. Chemotherapy rechallenge has resulted in a median PFS of 3.1 months and a median OS of 21.2 months, compared with 2.9 months (PFS) and 12.6 months (OS) for the FTD/TPI-regorafenib group. Multivariate analyses identified male sex and an Eastern Cooperative Oncology Group performance status (ECOG PS) of 0-1 as independent prognostic factors for better PFS, whereas chemotherapy rechallenge, localized stage at diagnosis, and an ECOG PS of 0-1 were significant prognostic factors for better OS.

CONCLUSION

This study suggests that chemotherapy rechallenge may provide a survival benefit in the third-line treatment of mCRC. However, patient characteristics, such as sex and ECOG PS, should also be considered in treatment decisions. Further prospective studies are required to confirm our findings.

Liquid biopsy in colorectal cancer: Onward and upward

Colorectal cancer (CRC) remains a leading cause of cancer-related deaths worldwide. In recent years, liquid biopsy has emerged as one of the most interesting areas of research in oncology, leading to innovative trials and practical changes in all aspects of CRC management. RNAs and cell free DNA (cfDNA) methylation are emerging as promising biomarkers for early diagnosis. Post-surgical circulating tumour DNA (ctDNA) can aid in evaluating minimal residual disease and personalising adjuvant treatment. In rectal cancer, ctDNA could improve response assessment to neoadjuvant therapy and risk stratification, especially in the era of organ-preservation trials. In the advanced setting, ctDNA analysis offers the opportunity to monitor treatment response and identify driver and resistance mutations more comprehensively than traditional tissue analysis, providing prognostic and predictive information. The aim of this review is to provide a detailed overview of the clinical applications and future perspectives of liquid biopsy in CRC.

Comparing the efficacy of regorafenib and 5-fluorouracil-based rechallenge chemotherapy in the third-line treatment of metastatic colorectal cancer

BACKGROUND

The optimal treatment for metastatic colorectal cancer (mCRC) after the second line is still controversial. Regorafenib has been the standard of care in this setting as it improved overall survival (OS) compared to placebo. In real-world practice chemotherapy rechallenge is also a preferred option even though supporting evidence is not enough. We aim to compare the efficacy of regorafenib and 5-fluorouracil-based (5-FU) rechallenge treatment in the third line setting of mCRC.

METHODS

In this retrospective multi-institutional trial, mCRC patients from 21 oncology centers who progressed after 2 lines of chemotherapy were analyzed. Patients who were treated with regorafenib or rechallenge therapy in the third-line setting were eligible. Rechallenge chemotherapy was identified as the re-use of the 5-FU based regimen which was administered in one of the previous treatment lines. OS, disease control rate (DCR), progression free survival (PFS) and toxicity were analyzed.

RESULTS

Three hundred ninety-four mCRC patients were included in the study. 128 (32.5%) were in the rechallenge, and 266 (67.5%) were in the regorafenib group. Median PFS was 5.82 months in rechallenge and 4 months in regorafenib arms (hazard ratio:1.45,95% CI, p = 0.167). DCR was higher in the rechallenge group than regorafenib (77% vs 49.5%, respectively, p =  < 0.001). Median OS after the third-line treatment was 11.99 (95% CI, 9.49-14.49) and 8.08 months (95% CI, 6.88-9.29) for rechallenge and regorafenib groups, respectively (hazard ratio:1.51, 95% CI, p < 0.001). More adverse effects and discontinuation were seen with regorafenib treatment.

CONCLUSION

Our study revealed that higher disease control and OS rates were achieved with rechallenge treatment compared to regorafenib, especially in patients who achieved disease control in one of the first two lines of therapy.

Treatment Options in Late-Line Colorectal Cancer: Lessons Learned from Recent Randomized Studies

Systemic treatment of metastatic colorectal cancer (mCRC) has improved considerably over the past 20 years. First- and second-line combinations of 5FU, oxaliplatin, and irinotecan, with or without anti-angiogenic and/or anti-EGFR antibodies, were approved shortly after the turn of the millennium. Further triumphs were not seen for almost 10 years, until the approval of initially regorafenib and shortly after trifluridine/tipiracil. A growing understanding of tumor biology through molecular profiling has led to further treatment options. Here, we review the most recent clinical data for late-line treatment options in mCRC, focusing on randomized trials if available. We include recommendations for options in unselected patients and therapies that should only be offered in patients with distinct tumor profiles (e.g., BRAF mutations, KRAS G12C mutations, HER2 amplification, deficient MMR, or NTRK gene fusions).

Panitumumab plus trifluridine/tipiracil as anti-EGFR rechallenge therapy in patients with refractory RAS wild-type metastatic colorectal cancer: Overall survival and subgroup analysis of the randomized phase II VELO trial

The randomized phase II VELO trial showed that the addition of panitumumab to trifluridine/tipiracil significantly improves progression-free survival (PFS) as compared to trifluridine/tipiracil in third-line therapy in patients with refractory RAS wild-type (WT) metastatic colorectal cancer (mCRC). With longer follow-up, final overall survival results and posttreatment subgroup analysis are presented. Sixty-two patients with refractory RAS WT mCRC were randomly assigned to receive, as third-line therapy, trifluridine/tipiracil alone (arm A) or in combination with panitumumab (arm B). Primary endpoint was PFS; secondary endpoints included overall survival (OS) and overall response rate (ORR). Median OS was 13.1 months (95% CI 9.5-16.7) in arm A compared to 11.6 months (95% CI 6.3-17.0) in arm B (HR: 0.96, 95% CI 0.54-1.71, P = .9). To evaluate the impact of subsequent lines of treatment, subgroup analysis was performed for the 24/30 patients in arm A, that received fourth-line therapy after disease progression. Median PFS was 4.1 months (95% CI 1.44-6.83) for 17 patients treated with anti-EGFR rechallenge as compared to 3.0 months (95% CI 1.61-4.31) for seven patients that received other therapies (HR: 0.29, 95% CI 0.10-0.85, P = .024). Median OS from the start of fourth-line treatment was 13.6 months (95% CI 7.2-20), and 5.1 months (95% CI 1.8-8.3) for patients treated with anti-EGFR rechallenge vs other therapies, respectively (HR: 0.30, 95% CI 0.11-0.81, P = .019). Final results of the VELO trial support the role of anti-EGFR rechallenge in the continuum of care of patients with RAS/BRAF WT mCRC.

Progress of research on molecular targeted therapies for colorectal cancer

Colorectal cancer (CRC) is one of the most common malignancies, accounting for approximately 10% of global cancer incidence and mortality. Approximately 20% of patients with CRC present metastatic disease (mCRC) at the time of diagnosis. Moreover, up to 50% of patients with localized disease eventually metastasize. mCRC encompasses a complex cascade of reactions involving multiple factors and processes, leading to a diverse array of molecular mechanisms. Improved comprehension of the pathways underlying cancer cell development and proliferation, coupled with the accessibility of relevant targeted agents, has propelled advancements in CRC treatment, ultimately leading to enhanced survival rates. Mutations in various pathways and location of the primary tumor in CRC influences the efficacy of targeted agents. This review summarizes available targeted agents for different CRC pathways, with a focus on recent advances in anti-angiogenic and anti-epidermal growth factor receptor agents, BRAF mutations, and human epidermal growth factor receptor 2-associated targeted agents.

CtDNA-guided rechallenge with anti-EGFR therapy in RASwt metastatic colorectal cancer: Evidence from clinical practice

AIM

To apply extended ctDNA-based RAS genotyping to clinical criteria for improving the selection of patients eligible for anti-EGFR-based rechallenge in a real-world setting.

METHODS

ctDNA testing was prospectively applied to RASwt mCRC progressed after a first-line anti-EGFR-containing regimen and at least one other line. The primary endpoint was the objective response rate.

RESULTS

Among ten enrolled patients, the anti-EGFR rechallenge resulted in an objective response rate and disease control rate of 70% and 90%. The median progression-free survival was 11.3 months and overall survival was not reached. Compared with a historical cohort retreated with anti-EGFR agents based on clinical criteria, the ctDNA-driven approach resulted in a higher chance of achieving an objective response and longer survival.

CONCLUSIONS

Blood-based RASwt status may enrich metastatic colorectal cancer more likely to benefit from anti-EGFR-based rechallenge. RAS genotyping in ctDNA represents a feasible, fast, and cost-effective tool to be implemented in the clinic for advancing precision medicine.

Case Report: Longitudinal monitoring of clonal evolution by circulating tumor DNA for resistance to anti-EGFR antibody in a case of metastatic colorectal cancer

Background

Treatment with anti-EGFR antibody has been shown to prolong survival in patients with RAS wild-type metastatic colorectal cancer (mCRC). However, even patients who initially respond to anti-EGFR antibody therapy, almost without exception, develop resistance to the therapy and then fail to respond. Secondary mutations in the mitogen-activated protein (MAPK) signaling pathway (mainly in NRAS and BRAF) have been implicated in anti-EGFR resistance. However, the process by which resistant clones develop during therapy has not been elucidated, and considerable intrapatient and interpatient heterogeneity exists. Circulating tumor DNA (ctDNA) testing has recently allowed the noninvasive detection of heterogeneous molecular alterations that underlie the evolution of resistance to anti-EGFR. In this report, we describe our observation of genomic alterations in KRAS and NRAS in a patient with acquired resistance to anti-EGFR antibody drugs by tracking clonal evolution using serial ctDNA anaylsis.

Case presentation

A 54-year-old woman was initially diagnosed with sigmoid colon cancer with multiple liver metastases. After receiving first-line mFOLFOX + cetuximab, second-line FOLFIRI + ramucirumab, third-line trifluridine/tipiracil + bevacizumab, fourth-line regorafenib, and fifth-line CAPOX + bevacizumab, she was rechallenged with CPT-11 + cetuximab. The best response to anti-EGFR rechallenge therapy was a partial response. RAS in the ctDNA was assessed during treatment. The RAS status changed from wild type to mutant type, back to wild type, and again to mutant type (NRAS/KRAS codon 61) during the course of treatment.

Conclusion

In this report, tracking of ctDNA allowed us to describe clonal evolution in a case in which we observed genomic alterations in KRAS and NRAS in a patient who acquired resistance to anti-EGFR antibody drugs during treatment. It is reasonable to consider repeat molecular interrogation during progression in patients with mCRC by using ctDNA analysis, which could help to identify patients who may benefit from a rechallenge strategy.

A Phase II Trial of Trifluridine/Tipiracil in Combination with Cetuximab Rechallenge in Patients with RAS Wild-Type mCRC Refractory to Prior Anti-EGFR Antibodies: WJOG8916G Trial

BACKGROUND

Trifluridine/tipiracil (FTD/TPI) improved the overall survival in patients with metastatic colorectal cancer (mCRC) who had previously received standard chemotherapies; however, the clinical outcomes remain poor.

OBJECTIVE

A multicenter phase II study aimed to assess the efficacy and safety of FTD/TPI plus cetuximab rechallenge.

PATIENTS AND METHODS

Patients with histologically confirmed RAS wild-type mCRC refractory to prior anti-epidermal growth factor receptor (anti-EGFR) antibody were enrolled and treated with FTD/TPI (35 mg/m² twice daily on days 1-5 and 8-12) plus cetuximab (initially 400 mg/m², followed by weekly 250 mg/m²) every 4 weeks. The primary endpoint was disease control rate (DCR), expecting a target DCR of 65% and null hypothesis of 45% with 90% power and 10% one-sided alpha error. Gene alterations of RAS, BRAF, EGFR, PIK3CA, ERBB2, and MET in pre-treatment circulating tumor DNA were evaluated using the Guardant360 assay.

RESULTS

A total of 56 patients (median age 60 years; left-sided tumors 91%; objective partial or complete response during the prior anti-EGFR therapy 61%) were enrolled. The DCR was 54% (80% confidence interval [CI] 44-63; P = 0.12), with a partial response rate of 3.6%. Median progression-free survival (PFS) was 2.4 months (95% CI 2.1-3.7). In the circulating tumor DNA analysis, patients without any alterations of the six genes (n = 20) demonstrated higher DCR (75% vs. 39%; P = 0.02) and longer PFS (median 4.7 vs. 2.1 months; P < 0.01) than those with any gene alterations (n = 33). The most common grade 3/4 hematologic adverse event was neutropenia (55%). No treatment-related deaths occurred.

CONCLUSIONS

FTD/TPI plus cetuximab rechallenge did not demonstrate clinically meaningful efficacy in all mCRC patients, but might be beneficial for the molecularly selected population.

Taxane rechallenge during metastatic disease in HER-2 negative breast cancer patients: Clinical activity, tolerance and survival results

BACKGROUND

Taxanes are major drugs for metastatic breast cancer (MBC) treatment, and are generally well tolerated, making them attractive for therapeutic reintroduction (rechallenge) during metastatic course. In view of the paucity of current literature, we questioned the usefulness of taxane rechallenge in a population of patients previously treated with taxanes in a metastatic setting.

METHODS

From the local database of a French cancer center, we retrospectively identified 756 patients diagnosed with ER+/HER2-, or triple negative MBC, and treated between 2008 and 2021. Among them, 58 patients (7.8%) were rechallenged with taxanes. Clinical characteristics, response rates, and survival were retrospectively evaluated and compared to patients who received taxanes only once.

RESULTS

Compared to non-rechallenged population, patients treated with taxane rechallenge were significantly younger, with better general status, and received more treatment. First taxane exposure led to better tumor response and was more frequently discontinued for reasons other than progression, compared to the non-rechallenged population. Taxane rechallenge led to an objective response rate of 27.6%, and a clinical benefit rate of 46.6%, with a median progression-free survival (PFS) of 5.7 months, and a median overall survival (OS) of 11.6 months. We also found a PFS2/PFS1 ratio >1.3 in 55.2% of the rechallenge population.

CONCLUSION

Although only a minority of MBC patients are concerned, taxane rechallenge appears to be a pragmatic option with an acceptable tolerance, and good efficacy, especially when these drugs have shown clinical activity earlier in the disease course, and/or have been stopped for reasons other than progression.

Rechallenge with anti-EGFR therapy to extend the continuum of care in patients with metastatic colorectal cancer

In patients with RAS wild-type metastatic colorectal cancer (mCRC), an anti-epidermal growth factor receptor (EGFR) monoclonal antibody plus chemotherapy is a standard option for treatment in the first-line setting. Patients who progress while on treatment with anti-EGFR-based therapy can be resistant to further anti-EGFR treatment, but evidence suggests that the anti-EGFR-resistant clones decay, thereby opening the potential for rechallenge or reintroduction in later lines of treatment. Results from recent clinical studies have shown that some patients with mCRC who are rechallenged with anti-EGFR monoclonal antibodies exhibit durable responses. While other therapies have demonstrated improved overall survival in chemorefractory mCRC over the past decade, rechallenge with anti-EGFR monoclonal antibodies in later lines of treatment represents a new option that deserves further investigation in clinical trials. In this review, we summarize the molecular rationale for rechallenge or reintroduction in patients with mCRC who have progressed on earlier-line anti-EGFR treatment and examine the current evidence for using liquid biopsy as a method for selecting rechallenge as a therapeutic option. We also provide an overview of published trials and trials in progress in this field, and outline the potential role of rechallenge in the current clinical setting.

New developments in targeted therapy for metastatic colorectal cancer

Colorectal cancer (CRC) is the second most lethal cancer worldwide and the prognosis of metastatic CRC (mCRC) remains poor. Recent advancements in translational research have led to the identification of several new therapeutic targets and improved the treatment outcome of patients with tumours harbouring BRAF V600E mutation, (HER2) ErBB2 alterations, NTRK gene fusions and KRAS(G12C) mutation. Improved understanding towards the mechanism of resistance to targeted therapy such as anti-epidermal growth factor receptor antibodies and the evolving role of therapeutic monitoring with circulating tumour DNA (ctDNA) has enabled the longitudinal tracking of clonal evolution during treatment and the individualization of subsequent treatments. To broaden the community-based implementation of precision oncology in directing targeted therapies for patients with gastrointestinal cancers including mCRC, the feasibility of 'Master Protocols' that utilizes ctDNA-based genotyping platforms is currently being evaluated. Such protocols encompass both observational and interventional clinical trials of novel targeted therapies conducted within a large clinical trial network. In this review, we will discuss the latest developments in targeted therapies, and therapeutic strategies for overcoming acquired drug resistance in patients with mCRC.

Cancer: slaying the nine-headed Hydra

Modern medicine continues to evolve, and the treatment armamentarium for various diseases grows more individualized across a breadth of medical disciplines. Cure rates for infectious diseases that were previously pan-fatal approach 100% because of the identification of the specific pathogen(s) involved and the use of appropriate combinations of drugs, where needed, to completely extinguish infection and hence prevent emergence of resistant strains. Similarly, with the assistance of technologies such as next-generation sequencing and immunomic analysis as part of the contemporary oncology armory, therapies can be tailored to each tumor. Importantly, molecular interrogation has revealed that metastatic cancers are distinct from each other and complex. Therefore, it is conceivable that rational personalized drug combinations will be needed to eradicate cancers, and eradication will be necessary to mitigate clonal evolution and resistance.

Phase II Single-Arm Study of Palbociclib and Cetuximab Rechallenge in Patients with KRAS/NRAS/BRAF Wild-Type Colorectal Cancer

BACKGROUND

Cetuximab is often administered to patients with KRAS wild-type (KRAS-WT) metastatic colorectal cancer (mCRC), although resistance inevitably develops. We hypothesized that co-inhibition of the epidermal growth factor receptor (EGFR) with cetuximab and downstream cyclin-dependent kinases (CDK) 4/6 with palbociclib would be effective for anti-EGFR rechallenge in KRAS-WT mCRC.

METHODS

We designed a single-arm, Simon's 2-stage, phase II trial of cetuximab and palbociclib in KRAS-WT mCRC treated with ≥2 prior lines of therapy. We report here on cohort B rechallenging patients with anti-EGFR-based therapy who had disease control of at least 4 months on prior anti-EGFR therapy. Primary endpoint was disease control rate (DCR) at 4 months.

RESULTS

Ten evaluable patients were enrolled in this cohort. The 4-month DCR was 20%, which did not fulfill the prespecified 4-month DCR rate to continue. Median progression-free survival was 1.8 months and median overall survival was 6.6 months. Three patients had stable disease, although overall response rate was 0%. Most common treatment-related grades 3-4 adverse events were lymphopenia and leukopenia.

CONCLUSION

Selection of patients for anti-EGFR rechallenge using clinical criteria alone was insufficient to identify response to palbociclib + cetuximab. Additional biomarkers are needed to select anti-EGFR rechallenge and circulating tumor DNA (ctDNA) analysis is planned for samples collected in this study. (ClinicalTrials.gov Identifier: NCT03446157).

Clinical Outcomes of Everolimus Rechallenge in Patients with Pancreatic Neuroendocrine Neoplasms with No Other Treatment Options

BACKGROUND

The clinical outcomes of everolimus rechallenge in patients with pancreatic neuroendocrine neoplasms (PNENs) are unknown. This study aimed to investigate the treatment outcomes and safety of everolimus rechallenge treatment with PNENs.

METHODS

Clinical data of everolimus-treated patients with PNENs at two institutions were collected. Patients who underwent everolimus rechallenge were included in the study. We analyzed the progression-free survival (PFS) and treatment response associated with everolimus rechallenge and the adverse events.

RESULTS

Between 2008 and 2020, 117 patients received initial treatment with everolimus, of which 14 patients received everolimus rechallenge. With regard to the grade of PNENs, there were 2 cases of G1, 11 cases of G2, and 1 case of G3. The median rechallenge PFS was 5.7 months. The objective response rate was 21.4%. the disease control rate was 71.4%. The only major grade 3 or 4 adverse event was neutropenia (n = 1, 7.1%). No other severe adverse event was observed.

CONCLUSION

The outcomes and safety of everolimus rechallenge were verified, and it was deemed an acceptable treatment. Everolimus rechallenge may provide a new drug therapy for patients with advanced PNENs for whom no other drug treatment option is available.

Current concepts of anti-EGFR targeting in metastatic colorectal cancer

Anti-EGFR targeting is one of the key strategies in the treatment of metastatic colorectal cancer (mCRC). For almost two decades oncologists have struggled to implement EGFR antibodies in the mCRC continuum of care. Both sidedness and RAS mutational status rank high among the predictive factors for the clinical efficacy of EGFR inhibitors. A prospective phase III trial has recently confirmed that anti-EGFR targeting confers an overall survival benefit only in left sided RAS-wildtype tumors when given in first line. It is a matter of discussion if more clinical benefit can be reached by considering putative primary resistance mechanisms (e.g., HER2, BRAF, PIK3CA, etc.) at this early stage of treatment. The value of this procedure in daily routine clinical utility has not yet been clearly delineated. Re-exposure to EGFR antibodies becomes increasingly crucial in the disease journey of mCRC. Yet re- induction or re-challenge strategies have been problematic as they relied on mathematical models that described the timely decay of EGFR antibody resistant clones. The advent of liquid biopsy and the implementation of more accurate next-generation sequencing (NGS) based high throughput methods allows for tracing of EGFR resistant clones in real time. These displays the spatiotemporal heterogeneity of metastatic disease compared to the former standard radiographic assessment and re-biopsy. These techniques may move EGFR inhibition in mCRC into the area of precision medicine in order to apply EGFR antibodies with the increase or decrease of EGFR resistant clones. This review critically discusses established concepts of tackling the EGFR pathway in mCRC and provides insight into the growing field of liquid biopsy guided personalized approaches of EGFR inhibition in mCRC.

Randomized phase II trial of FOLFIRI-panitumumab compared with FOLFIRI alone in patients with RAS wild-type circulating tumor DNA metastatic colorectal cancer beyond progression to first-line FOLFOX-panitumumab: the BEYOND study (GEMCAD 17-01)

PURPOSE

Panitumumab plus FOLFOX (P-FOLFOX) is standard first-line treatment for RAS wild-type (WT) metastatic colorectal cancer. The value of panitumumab rechallenge is currently unknown. We assessed addition of panitumumab to FOLFIRI (P-FOLFIRI) beyond progression to P-FOLFOX in patients with no RAS mutations in liquid biopsy (LB).

METHODS

In this randomized phase II trial, patients were assigned (3:2 ratio) to second-line P-FOLFIRI (arm A) or FOLFIRI alone (arm B). LB for circulating tumor DNA analysis was collected at study entry and at disease progression. Primary endpoint was 6-month progression-free survival. Two-stage Simon design required 85 patients to be included (EudraCT 2017-004519-38).

RESULTS

Between February 2019 and November 2020, 49 patients were screened (16 RAS mutations in LB detected) and 31 included (18 assigned to arm A and 13 to arm B). The study was prematurely closed due to inadequate recruitment. Serious adverse events were more frequent in arm A (44% vs. 23%). Overall response rate was 33% (arm A) vs. 7.7% (arm B). Six-month progression-free survival rate was 66.7% (arm A) and 38.5% (arm B). Median progression-free survival was 11.0 months (arm A) and 4.0 months (arm B) (hazard ratio, 0.58). At disease progression, RAS or BRAF mutations in LB were found in 4/11 patients (36%) in arm A and 2/10 (20%) in arm B.

CONCLUSIONS

The BEYOND study suggests a meaningful benefit of P-FOLFIRI beyond progression to P-FOLFOX in metastatic colorectal cancer patients with WT RAS status selected by LB. This strategy deserves further investigation.

Clinical management of metastatic colorectal cancer in the era of precision medicine

Colorectal cancer (CRC) represents approximately 10% of all cancers and is the second most common cause of cancer deaths. Initial clinical presentation as metastatic CRC (mCRC) occurs in approximately 20% of patients. Moreover, up to 50% of patients with localized disease eventually develop metastases. Appropriate clinical management of these patients is still a challenging medical issue. Major efforts have been made to unveil the molecular landscape of mCRC. This has resulted in the identification of several druggable tumor molecular targets with the aim of developing personalized treatments for each patient. This review summarizes the improvements in the clinical management of patients with mCRC in the emerging era of precision medicine. In fact, molecular stratification, on which the current treatment algorithm for mCRC is based, although it does not completely represent the complexity of this disease, has been the first significant step toward clinically informative genetic profiling for implementing more effective therapeutic approaches. This has resulted in a clinically relevant increase in mCRC disease control and patient survival. The next steps in the clinical management of mCRC will be to integrate the comprehensive knowledge of tumor gene alterations, of tumor and microenvironment gene and protein expression profiling, of host immune competence as well as the application of the resulting dynamic changes to a precision medicine-based continuum of care for each patient. This approach could result in the identification of individual prognostic and predictive parameters, which could help the clinician in choosing the most appropriate therapeutic program(s) throughout the entire disease journey for each patient with mCRC. CA Cancer J Clin. 2022;72:000-000.

Circulating Tumor DNA in Identifying Resistant Sub-Clones Post EGFR Blockade: Implications for EGFR Rechallenge

For patients with metastatic RAS/RAF wild-type refractory colorectal cancer, the question of anti-EGFR therapy rechallenge often comes up after initial use. However, not all patients derive benefit. It is now well known that these tumors acquire mechanisms of resistance in the mitogen-activated protein kinase (MAPK) pathway, which can be detected on circulating tumor DNA (ctDNA)-based testing. We present a series of patients who had serial testing post-EGFR blockade showing its feasibility and value. This would have implications for EGFR rechallenge. We reviewed records for patients who were initially noted to be RAS/RAF wild-type on tissue, who received prior anti-EGFR therapy and then subsequently had at least one circulating tumor DNA-based testing. These patients also had tissue-based genomic testing obtained earlier as part of their standard of care, alongside serial ctDNA-based testing that was done later when subsequent lines of therapy were being decided. The median duration of initial prior anti-EGFR therapy was around 10 months. Known acquired mechanisms of resistance were noted in 100% of the cases. These included KRAS, NRAS, extracellular domain mutations in EGFR, and BRAF mutations. Interestingly, the levels of the sub-clones expressed in variant allele fraction percentage varied and decreased over time in relation to timing of the prior EGFR exposure. Additionally, these were noted to be polyclonal, and the number of clones also varied including some disappearing over time during non-EGFR-based therapy (EGFR holiday). Patients’ post-EGFR blockade may have multiple mechanisms of acquired resistance that can be easily detected on non-invasive liquid biopsies. These patients do not benefit from EGFR rechallenge based on the results of the recently reported CRICKET (NCT02296203) and CAVE (NCT04561336) clinical trials. Furthermore, excluding these patients from EGFR rechallenge is already being adopted in prospectively done clinical trials, e.g., the CHRONOS study (NCT03227926). Rechecking the liquid biopsy plasma RAS/RAF status is one thing that may be incorporated into practice with EGFR rechallenge only a consideration if acquired mechanisms of resistance are absent.

KRAS Gene Copy Number as a Negative Predictive Biomarker for the Treatment of Metastatic Rectal Cancer With Cetuximab: A Case Report

Background

Close to one third of colorectal cancer (CRC) patients are diagnosed with metastatic CRC (mCRC). Patients with wild-type RAS and BRAF usually receive anti-EGFR monoclonal antibody therapy containing cetuximab. Overall, 30–50% of mCRC patients are reported to harbor RAS mutations, and RAS mutation status should be assessed when considering EGFR inhibitor treatment according to mCRC biomarker guidelines. Of note, 0.67–2% of patients with CRC harbored a KRAS amplification. Here we reported a case of advanced rectal cancer with wild-type RAS and BRAF in a male patient who harbored a KRAS amplification during anti-EGFR treatment.

Case Presentation

A 46-year-old man was diagnosed with rectal adenocarcinoma with liver metastases (cT3NxM1a, stage IVA). After receiving first-line irinotecan- fluorouracil chemotherapy (FOLFIRI) plus cetuximab, second-line capecitabine- oxaliplatin chemotherapy (XELOX) plus bevacizumab, and third-line regorafenib, he rechallenged FOLFIRI and cetuximab for seven cycles, achieving a prolonged survival of at least 5 months. The KRAS copy number of circulating tumor DNA (ctDNA) was assessed during treatment. Notably, apart from serum carbohydrate antigen 199 (CA199) and carcinoembryonic antigen (CEA), the change of plasm Kirsten Rat Sarcoma Viral Oncogene Homolog (KRAS) copy number appeared to strongly correlate with treatment response.

Conclusion

Our findings suggest that the dynamic change of KRAS copy number on ctDNA during treatment might be a negative predictive biomarker. Additionally, RAS and BRAF wild-type mCRC patients who are resistant to first-line FOLFIRI plus cetuximab therapy may respond well to the FOLFIRI plus cetuximab “rechallenged” strategy.

Liquid Biopsy-Driven Cetuximab Rechallenge Strategy in Molecularly Selected Metastatic Colorectal Cancer Patients

Background

Rechallenge with EGFR inhibitors represents a promising strategy for patients with RAS wild type (WT) colorectal cancer (CRC) but definitive selection criteria are lacking. Recently, the RAS WT status on circulating tumor DNA (ct-DNA) emerged as a potential watershed for this strategy. Our study explored the liquid biopsy-driven cetuximab rechallenge in a RAS and BRAF WT selected population.

Methods

CRC patients with RAS and BRAF WT both on tumor tissue and on ct-DNA at baseline receiving rechallenge with cetuximab were eligible for our analysis. Ct-DNA was analyzed for RAS-BRAF mutations with pyro-sequencing and nucleotide sequencing assays. Real-time PCR and droplet digital PCR were performed to confirm the RAS-BRAF mutational status.

Results

A total of 26 patients were included in our analysis. In the global population, RR was 25.0%, median overall survival (mOS) was 5.0 months, and median progression-free survival (mPFS) was 3.5 months. Previous response to anti-EGFR was associated with improved mPFS (5.0 vs. 2.0 months, HR: 0.26, p = 0.048); anti-EGFR free interval > 14 months and anti-EGFR free interval > 16 months were associated with improved mPFS (respectively 7.0 vs. 3.0 months, HR: 0.27, p = 0.013 and not reached vs. 3.0 months, HR: 0.20, p = 0.002) and with improved mOS (respectively 13.0 vs. 5.0 months, HR: 0.27, p = 0.013 and 13.0 vs. 5.0 months, HR: 0.20, p = 0.002). Previous lines >2 were correlated with improved mPFS (4.0 vs. 1.0 month, HR: 0.05, p = 0.041) and with improved mOS (7.0 vs. 1.0 month, HR: 0.045, p = 0.034). In a multiple logistic regression model, only the anti-EGFR free interval was confirmed to be a significant predictor for mOS and mPFS.

Conclusions

Liquid biopsy-driven cetuximab rechallenge was confirmed to be effective. The clinical outcome was consistent with available results from phase II studies. In addition to the molecular selection through the analysis of ct-DNA for RAS, the long anti-EGFR free interval is confirmed as a prospective selection criterion for this therapeutic option.

Circulating Tumor DNA: An Emerging Tool in Gastrointestinal Cancers

Circulating tumor DNA (ctDNA) is tumor-derived fragmented DNA in the bloodstream that has come from primary or metastatic cancer sites. Neoplasm-specific genetic and epigenetic abnormalities are increasingly being identified through liquid biopsy: a novel, minimally invasive technique used to isolate and analyze ctDNA in the peripheral circulation. Liquid biopsy and other emerging ctDNA technologies represent a paradigm shift in cancer diagnostics because they allow for the detection of minimal residual disease in patients with early-stage disease, improve risk stratification, capture tumor heterogeneity and genomic evolution, and enhance ctDNA-guided adjuvant and palliative cancer therapy. Moreover, ctDNA can be used to monitor the tumor response to neoadjuvant and postoperative therapy in patients with metastatic disease. Using clearance of ctDNA as an endpoint for escalation/de-escalation of adjuvant chemotherapy for patients considered to have high-risk disease has become an important area of research. The possibility of using ctDNA as a surrogate for treatment response-including for overall survival, progression-free survival, and disease-free survival-is an attractive concept; this surrogate will arguably reduce study duration and expedite the development of new therapies. In this review, we summarize the current evidence on the applications of ctDNA for the diagnosis and management of gastrointestinal tumors. Gastrointestinal cancers-including tumors of the esophagus, stomach, colon, liver, and pancreas-account for one-quarter of global cancer diagnoses and contribute to more than one-third of cancer-related deaths. Given the prevalence of gastrointestinal malignancies, ctDNA technology represents a powerful tool to reduce the global burden of disease.

Anti-EGFR Reintroduction and Rechallenge in Metastatic Colorectal Cancer (mCRC): A Real-World Analysis

BACKGROUND AND AIMS

In patients with Rat sarcoma proto-oncogene (RAS) wild-type metastatic colorectal cancer (mCRC), anti-epidermal growth factor receptor (EGFR) antibodies have been established in first- and further therapy lines. Due to limited treatment options upon disease progression, anti-EGFR re-exposure is increasingly employed in real-world oncology. The aim of this study was to assess clinical implementation and utility of anti-EGFR retreatment strategies in real-world mCRC patients.

METHODS

In this monocentric retrospective study, we included 524 patients with CRC and identified patients who received an anti-EGFR-based treatment as well as anti-EGFR rechallenge (progression on first-line anti-EGFR therapy) or reintroduction (discontinuation due to intolerance/toxicity/other).

RESULTS

In total, 143 patients received an anti-EGFR-based first- or second-line treatment, showing a similar overall survival (OS) compared to the non-anti-EGFR treatment group (38.3 vs. 39.6 months, p = 0.88). Thirty-three patients met the inclusion criteria for anti-EGFR re-exposure and were either assigned to rechallenge (n = 21) or reintroduction (n = 12) subgroups. The median FU after re-exposure was 45.8 months. Cetuximab and Panitumumab were used in 21 and 12 patients, respectively, and the main chemotherapy at re-exposure was FOLFIRI in 39.4%. Anti-EGFR re-exposure was associated with a distinct trend towards a better outcome (median OS 56.0 vs. 35.4 months, p = 0.06). In a subgroup comparison, reintroduction was associated with a higher OS and PFS in trend compared to the rechallenge (mOS 66 vs. 52.4, n.s., mPFS 7.33 vs. 3.68 months, n.s.).

CONCLUSIONS

This retrospective study provides real-world evidence underscoring that anti-EGFR re-exposure strategies might benefit patients independently of the reason for prior discontinuation.

Liquid profiling of circulating tumor DNA in colorectal cancer: steps needed to achieve its full clinical value as standard care

The analysis of circulating tumor DNA (ctDNA) is at the threshold of implementation into standard care for colorectal cancer (CRC) patients. However, data about the clinical utility of liquid profiling (LP), its acceptance by clinicians, and its integration into clinical workflows in real‐world settings remain limited. Here, LP tests requested as part of routine care since 2016 were retrospectively evaluated. Results show restrained request behavior that improved moderately over time, as well as reliable diagnostic performance comparable to translational studies, with an overall agreement of 91.7%. Extremely low ctDNA levels at < 0.1% in over 20% of cases, a high frequency of concomitant driver mutations (in up to 14% of cases), and ctDNA levels reflecting the clinical course of disease were revealed. However, certain limitations hampering successful translation of ctDNA into clinical practice were uncovered, including the lack of clinically relevant ctDNA thresholds, appropriate time points of LP requests, and integrative evaluation of ctDNA, imaging, and clinical findings. In conclusion, these results highlight the potential clinical value of LP for CRC patient management and demonstrate issues that need to be addressed for successful long‐term implementation in clinical workflows.

Skin Toxicity as Predictor of Survival in Refractory Patients with RAS Wild-Type Metastatic Colorectal Cancer Treated with Cetuximab and Avelumab (CAVE) as Rechallenge Strategy

The single-arm phase II CAVE mCRC trial evaluated the combination of cetuximab plus avelumab as rechallenge strategy in RAS wild-type (WT) metastatic colorectal cancer (mCRC) patients, with clinical response to first-line anti-EGFR-based chemotherapy, who progressed and received a subsequent line of therapy. The correlation of skin toxicity (ST) and different clinico-molecular variables with overall survival (OS), progression-free survival (PFS) and response rate (RR) was assessed at univariate and multivariate analysis. A total of 33/77 (42.9%) patients experienced grade 2-3 ST and displayed median OS (mOS) of 17.8 months (CI 95%, 14.9-20.6); whereas 44/77 (57.1%) patients with grade 0-1 ST exhibited mOS of 8.2 months (CI 95%, 5.5-10.9), (hazard ratio (HR), 0.51; CI 95%, 0.29-0.89; p = 0.019). Median PFS (mPFS) was 4.6 months (CI 95%, 3.4-5.7) in patients with grade 2-3 ST, compared to patients with grade 0-1 ST with mPFS of 3.4 months (CI 95%, 2.7-4.1; HR, 0.49; CI 95%, 0.3-0.8; p = 0.004). Grade 2-3 ST (HR, 0.51; CI 95%, 0.29-0.89; p = 0.019) and RAS/BRAF/EGFR WT circulating tumor DNA (ctDNA) (HR, 0.50; CI 95%, 0.27-0.9; p = 0.019) had a statistically significant effect on OS at univariate analysis. At the multivariate analysis, RAS/BRAF/EGFR WT ctDNA status maintained statistical significance (HR, 0.49; CI 95%, 0.27-0.9; p = 0.023), whereas there was a trend towards ST grade 2-3 (HR, 0.54; CI 95%, 0.29-1.01; p = 0.054). Skin toxicity is a promising biomarker to identify patients with mCRC that could benefit of anti-EGFR rechallenge.

Phase II Study of Third-Line Panitumumab Rechallenge in Patients with Metastatic Wild-Type KRAS Colorectal Cancer Who Obtained Clinical Benefit from First-Line Panitumumab-Based Chemotherapy: JACCRO CC-09

BACKGROUND

Regorafenib and trifluridine/tipiracil are standard third-line chemotherapies for colorectal cancer patients, but their efficacy is limited. Anti-epidermal growth factor receptor antibody rechallenge has been reported to be promising for patients who have obtained clinical benefit from first-line cetuximab-based chemotherapy. Moreover, panitumumab showed non-inferior efficacy to cetuximab.

OBJECTIVE

This study assessed the efficacy and safety of third-line panitumumab rechallenge in patients with metastatic KRAS exon 2 wild-type metastatic colorectal cancer who obtained clinical benefit from first-line panitumumab-based chemotherapy.

PATIENTS AND METHODS

This was a prospective, multicenter, phase II trial conducted from October 2013 to August 2017. Major eligibility criteria included KRAS exon 2 wild-type and achievement of complete response, partial response, or continued stable disease for at least 6 months in first-line panitumumab-based therapy. Irinotecan plus panitumumab treatment was continued until disease progression or unacceptable toxicity was observed. The primary endpoint was the 3-month progression-free survival (PFS) rate.

RESULTS

Twenty-five patients were enrolled in this study. Their median age was 66.5 years, and the 3-month PFS rate was 50.0% (95% confidence interval 30.0-70.0). The median PFS and overall survival were 3.1 months and 8.9 months, respectively. The response rate and disease control rate were 8.3% and 50.0%, respectively. Common grade 3/4 adverse events were acneiform rash (17%), hypomagnesemia (13%), and dry skin (13%). No treatment-related deaths occurred.

CONCLUSION

Irinotecan plus panitumumab rechallenge is a promising third-line treatment regimen in patients with metastatic wild-type KRAS colorectal cancer.

CLINICAL TRIAL IDENTIFICATION

UMIN000015916.

A Possible Distinct Molecular Subtype (Quintuple-Wildtype) of Metastatic Colorectal Cancer in First-Line Anti-EGFR Therapy with Cetuximab Plus FOLFIRI - Palliative Precision Therapy and a Multidisciplinary Treatment Approach: Interim Analysis of the IVOPAK II Trial with Early Results

OBJECTIVE

The study aimed to prospectively evaluate a new molecular biomarker panel (KRAS, NRAS, BRAF, PIK3CA, and ERBB2) for palliative first-line treatment of colorectal cancer (CRC), including a multidisciplinary treatment approach. The rate of secondary metastasis resections was assessed.

PATIENTS AND METHODS

A total of 40 patients with definitively nonresectable metastatic CRC were enrolled from 10 centers before the interim analysis (June 2019) of the IVOPAK II trial (Interdisciplinary Care with Quality Control in Palliative Treatment of Colorectal Cancer). After determination of 5 molecular biomarkers in the tumor (KRAS, exons 2-4; NRAS, exons 2-4; BRAF V600E; PIK3CA; and ERBB2), patients in the IVOPAK II study received FOLFIRI plus cetuximab for all-RAS/quintuple-wildtype disease and FOLFIRI plus bevacizumab in the case of RAS mutations. The current article presents the early description of the clinical outcome of the interim analysis of IVOPAK II comparing the all-RAS/quintuple-wildtype and RAS-mutations populations, including a multidisciplinary-treated case report of a quintuple-wildtype patient.

RESULTS

The quintuple-wildtype population treated with FOLFIRI plus cetuximab in first-line exhibited a significantly higher response rate and enhanced early tumor shrinkage in the interim analysis than the RAS-mutations population, as well as a high rate of secondary metastatic resections.

CONCLUSION

Initial results of this new biomarker panel (quintuple-wildtype) are promising for anti-EGFR therapy with cetuximab plus doublet chemotherapy (FOLFIRI) in first-line treatment of metastatic CRC. These results warrant confirmation with higher case numbers in the IVOPAK II trial.

Tumor growth rate during re-challenge chemotherapy with previously used agents as salvage treatment for metastatic colorectal cancer: A retrospective study

BACKGROUND

In clinical practice, the same chemotherapeutic agents are occasionally reused (re-challenge) after failure of all available standard chemotherapy options for metastatic colorectal cancer (mCRC). However, the benefits of re-challenge chemotherapy (Re-Cx) are unclear. This retrospective study evaluated the efficacy of Re-Cx, focusing on the tumor growth rate (TGR).

METHODS

The study included mCRC patients with measurable lesions who received Re-Cx from November 2011 to October 2018 at National Cancer Center Hospital. Re-Cx was defined as re-administration of agents which had been used in prior lines of chemotherapy and discontinued due to disease progression. We compared the TGR immediately after initiating Re-Cx regimens with that observed at the time of disease progression during prior chemotherapy (Prior-Cx) immediately before Re-Cx.

RESULTS

Of the 25 patients who received Re-Cx, five patients received two Re-Cx regimens. Therefore, a total of 30 cases of Re-Cx were analyzed in this study. The regimens of Re-Cx were oxaliplatin based (19 cases), irinotecan based (8 cases), and others (3 cases). Although the objective response rate to Re-Cx was 0%, the disease control rate was 60% (18 cases), and 40% (12 cases) showed some tumor shrinkage. We compared the effects of Re-Cx and Prior-Cx by the TGR and found that the TGR of Re-Cx was slower than that recorded in Prior-Cx in 26 of 30 cases (87%). In particular, the ratio of% TGR <0, which indicates tumor shrinkage, was obtained in 13 of 30 cases (43.3%). The median progression-free survival and overall survival after Re-Cx were 3.8 and 6.57 months, respectively.

CONCLUSION

We found that Re-Cx may have some anti-tumor efficacy as salvage treatment for mCRC and these results also suggested the clinical benefits of Re-Cx.

Tackling Refractory Metastatic Colorectal Cancer: Future Perspectives

Substantial improvements have characterized the systemic treatment of metastatic colorectal cancer (mCRC) over the past 20 years. Besides strong evidence that supports the use of RAS and BRAF status as prognostic and predictive indicators of disease and response, novel technologies have made possible the incorporation of emerging biomarkers for the management of mCRC. On one hand, the discovery of point mutations, amplifications, fusions, and gene expression profiles highlights the genomic and dynamic complexity of CRC. On the other, such discoveries are leading to newer biomarker-driven strategies that add to existing anti-epidermal growth factor receptor (EGFR) and anti-angiogenic approaches. In addition, the availability of a wide molecular profiling has relevant implications for patient prognosis and treatment benefits. Here, we will review the molecular underpinnings and clinical data supporting novel targeted treatments under development for refractory mCRC harboring BRAF mutations, KRAS G12C mutations, HER2 amplification, and less common molecular alterations, such as the re-arrangements of NTRK, ALK, and ROS1. Additionally, we will discuss novel strategies driving the rechallenge of EGFR antibodies and the incorporation of newer anti-angiogenic agents in the therapeutic armamentarium.

Cetuximab Rechallenge Plus Avelumab in Pretreated Patients With RAS Wild-type Metastatic Colorectal Cancer: The Phase 2 Single-Arm Clinical CAVE Trial

Importance

Rechallenge therapy with anti-epidermal growth factor receptor (EGFR) drugs has been suggested in patients with chemo-refractory RAS wild-type (WT) metastatic colorectal cancer (mCRC) after initial response to anti-EGFR-based first-line treatment. The association of treatment with cetuximab plus avelumab with overall survival (OS) may be worthy of investigation in this setting.

Objective

To assess the efficacy and safety of cetuximab rechallenge therapy plus avelumab.

Design, Setting, and Participants

This single-arm, multicenter phase 2 trial enrolled patients from August 2018 to February 2020. Eligible patients with RAS WT mCRC had a complete or partial response to first-line chemotherapy plus anti-EGFR drugs, developed acquired resistance, and failed second-line therapy. Baseline circulating tumor DNA (ctDNA) for KRAS, NRAS, BRAF, and EGFR-S492R mutation analysis was done.

Interventions

Patients received avelumab (10 mg/kg every 2 weeks) and cetuximab (400 mg/m2 and, subsequently, 250 mg/m2 weekly) until disease progression or unacceptable toxic effects.

Main Outcomes and Measures

The primary end point was OS. Secondary end points were progression-free survival (PFS), overall response rate (ORR), and safety.

Results

Seventy-seven patients were enrolled (42 men, 35 women; median age, 63 years); 71 had microsatellite stable tumors (MSS), 3 microsatellite instability-high tumors (MSI-H), 3 unknown. The study met the primary end point, with median OS (mOS) of 11.6 months (95% CI, 8.4-14.8 months). Median PFS (mPFS) was 3.6 months (95% CI, 3.2-4.1 months). Common grade-3 adverse events were cutaneous eruption, 11 (14%), and diarrhea, 3 (4%). For 67 of 77 (87%) patients, baseline analysis of plasma circulating tumor DNA (ctDNA) for KRAS, NRAS, BRAF, and EGFR-S492R variations was feasible. Forty-eight patients had WT disease, whereas 19 had mutations. Patients with RAS/BRAF WT ctDNA had mOS of 17.3 months (95% CI, 12.5-22.0 months) compared with 10.4 months (95% CI, 7.2-13.6 months) in patients with mutated ctDNA (hazard ratio [HR], 0.49; 95% CI, 0.27-0.90; P = .02). The mPFS was 4.1 months (95% CI, 2.9-5.2 months) in RAS/BRAF WT patients compared with 3.0 months (95% CI, 2.6-3.5 months) in patients with mutated ctDNA (HR, 0.42; 95% CI, 0.23-0.75; P = .004).

Conclusions and Relevance

The findings of this single-arm phase 2 trial suggest that cetuximab plus avelumab is an active, well tolerated rechallenge therapy in RAS WT mCRC. Plasma ctDNA analysis before treatment may allow selection of patients who could benefit.

Trial Registration

ClinicalTrials.gov Identifier: NCT04561336.

Mitogen-activated protein kinase blockade in melanoma: intermittent versus continuous therapy, from preclinical to clinical data

PURPOSE OF REVIEW

Although targeted therapy provides a high response rate and rapid disease control in advanced melanoma, most patients experience disease progression due to acquired resistance mechanisms leading to reactivation of mitogen-activated protein kinase pathway. The purpose of this article is to review the recently published data on the impact of an intermittent versus continuous dosing schedule of BRAF and MEK inhibition in advanced melanoma to determine the best approach in clinical practice.

RECENT FINDINGS

Some preclinical studies have highlighted the concept that drug-resistant cells may also display drug dependency, such that intermittent dosing of targeted therapy may prevent the emergence of lethal drug resistance. Moreover, clinical observations have suggested that repeated treatment after a break or an intervening therapy may provide clinical benefit. However, recent preclinical and clinical studies have also failed to demonstrate an advantage of intermittent dosing and showed a similar efficacy of the intermittent versus continuous regimens of BRAF and MEK inhibitors in mice models and phase 2 clinical trial.

SUMMARY

Owing to these discordant results, continuous dosing of BRAF and MEK inhibitors remains the optimal therapeutic approach until additional clinical data demonstrate the superiority of another combination or dosing regimen.

Rationale and Study Design of the PARERE Trial: Randomized phase II Study of Panitumumab Re-Treatment Followed by Regorafenib Versus the Reverse Sequence in RAS and BRAF Wild-Type Chemo-Refractory Metastatic Colorectal Cancer Patients

BACKGROUND

A recent phase II randomized Japanese study reported better survival with regorafenib followed at progression by cetuximab ± irinotecan compared with the reverse standard sequence in chemo-refractory and anti-EGFR-naïve, RAS wild-type (wt) mCRC patients. Nowadays the use of anti-EGFR antibodies is more frequently anticipated to the first-line of therapy especially in patients with left-sided RAS/BRAF wt tumours. However, retrospective analyses and phase II single-arm trials showed promising activity of re-using anti-EGFRs in metastatic colorectal cancer (mCRC) patients who previously achieved benefit from a first-line anti-EGFR-based treatment. Post-hoc analyses of these trials revealed that the detection of RAS mutations in circulating tumour DNA (ct-DNA) at the time of re-treatment may be useful to identify resistant patients.

PATIENTS AND METHODS

PARERE (NCT04787341) is a prospective, open label, multicentre phase II study in which 214 RAS/BRAF wt chemo-refractory mCRC patients with previous benefit from first-line anti-EGFR-based treatment and RAS/BRAF wt ct-DNA in the liquid biopsy collected at the time of inclusion will be randomized in a 1:1 ratio to receive panitumumab followed after progression by regorafenib versus the reverse sequence. Primary endpoint is overall survival. Secondary endpoints are 1st-progression free-survival (PFS), 2nd-PFS, time to failure strategy, objective response rate, and safety.

AIM OF THE STUDY

The aim of this study is to validate the role of anti-EGFR retreatment and its proper placement in the therapeutic route of mCRC patients selected according to the analysis of ct-DNA in liquid biopsy. Results are expected at the end of 2023.

The Opportunities and Challenges of Molecular Tagging Next-Generation Sequencing in Liquid Biopsy

Liquid biopsy (LB) is a promising tool that is rapidly evolving as a standard of care in early and advanced stages of cancer settings. Next-generation sequencing (NGS) methods have become essential in molecular diagnostics and clinical laboratories dealing with LB analytes, i.e., cell-free DNA and RNA. The sensitivity and high-throughput capacity of NGS enable us to overcome technical issues that are mainly attributable to low-abundance (below 1% mutated allelic frequency) tumour genetic material circulating within biological fluids. In this context, the introduction of unique molecular identifiers (UMIs), also known as molecular barcodes, applied to various NGS platforms greatly improved the characterization of rare genetic alterations, as they resulted in a drastic reduction in background noise while maintaining high levels of positive predictive value and sensitivity. Different UMI strategies have been developed, such as single (e.g., safe-sequencing system, Safe-SeqS) or double (duplex-sequencing system, Duplex-Seq) strand-based labelling, and, currently, considerable results corroborate their potential implementation in a routine laboratory. Recently, the US Food and Drug Administration approved the clinical use of two comprehensive UMI-based NGS assays (FoundationOne Liquid CDx and Guardant360 CDx) in cfDNA mutational assessment. However, to definitively translate LB into clinical practice, UMI-based NGS protocols should meet certain feasibility requirements in terms of cost-effectiveness, wet laboratory performance and easy access to web-source and bioinformatic tools for downstream molecular data.

Successful rechallenge with cetuximab after progression with nivolumab for recurrent cervical lymph node metastasis from carcinoma of the tongue

We can infer that the immunostimulatory effect of nivolumab and reactivation of cetuximab enhance the antitumor effect of the therapy.

Perspectives for circulating tumor DNA in clinical management of colorectal cancer

Growing evidence has demonstrated that circulating tumor DNA (ctDNA) detection in colorectal cancer might be a promising approach to address current important clinical questions. During chemotherapy for metastatic colorectal cancer, tumor cells acquire potential resistance by generating additional somatic mutations related to therapeutic resistance. ctDNA can capture the tumor landscape, including heterogeneity, which might provide the opportunity for additional treatment options. Moreover, ctDNA detection is advantageous, because it can monitor tumor heterogeneity serially, in a non-invasive manner. ctDNA is considered valid for detecting minimal residual disease after a curable resection. By utilizing ctDNA detection, adjuvant chemotherapy for patients with stage II-III colorectal cancer might be omitted for patients at low risk of recurrence; or conversely, adjuvant chemotherapy might be highly recommended for patients at high risk, based on ctDNA findings. During multidisciplinary treatments for locally advanced rectal cancer, it is essential to monitor the responses to sequential treatments to make appropriate decisions. Currently, these decisions are mainly based on radiological or pathological findings. ctDNA can add value by providing the real-time status of locally advanced rectal cancer. In this review, we summarized the current evidence and discussed future strategies for using ctDNA in the treatment of colorectal cancer.

REMARRY and PURSUIT trials: liquid biopsy-guided rechallenge with anti-epidermal growth factor receptor (EGFR) therapy with panitumumab plus irinotecan for patients with plasma RAS wild-type metastatic colorectal cancer

BACKGROUND

Previous clinical trials have demonstrated the potential efficacy of rechallenge with anti- epidermal growth factor receptor (EGFR) monoclonal antibodies (mAbs) for patients with RAS/BRAF V600E wild-type metastatic colorectal cancer (mCRC). Moreover, post hoc biomarker analyses of clinical trials has suggested that RAS status in circulating tumor DNA (ctDNA) has a high probability to select patients who could benefit from anti-EGFR mAb rechallenge.

METHODS

This trial is composed of 2 phases: a monitoring phase (REMARRY) and a trial phase (PURSUIT). A monitoring phase, the REMARRY study, aims to evaluate the dynamics of plasma RAS status during the subsequent treatments after refractory to anti-EGFR therapy in patients with mCRC with RAS/BRAF V600E wild-type tumors who have progressed after a response to previous anti-EGFR therapy, using a highly sensitive digital polymerase chain reaction OncoBEAM RAS CRC kit in a central laboratory (Sysmex, Japan). A trial phase, the PURSUIT trial, is a multicenter, single-arm phase II trial to assess the efficacy and safety of rechallenge therapy with panitumumab plus irinotecan in patients without RAS mutations in ctDNA (plasma RAS negative) in the REMARRY study. Key eligibility criteria of the PURSUIT trial include RAS/BRAF V600E wild-type mCRC in tumor tissue refractory or intolerant to fluoropyrimidine, oxaliplatin, and irinotecan; progression after complete or partial response to previous anti-EGFR therapy; plasma RAS negative (defined as plasma mutant allele frequencies [MAF] of all RAS ≤ 0.1%) within 28 days prior to enrollment; 4 months or more between the last administration of previous anti-EGFR mAb and the start of protocol treatment; and Eastern Cooperative Oncology Group (ECOG) Performance Status (PS) ≤ 1. The primary endpoint is the confirmed objective response rate (ORR). The target sample size of the PURSUIT trial is 50 patients. Biomarker analyses will be performed in parallel using the OncoBEAM RAS CRC kit and a next-generation sequencing-based ctDNA analysis (Guardant360).

DISCUSSION

Our trial aims to confirm the clinical benefit of anti-EGFR mAb rechallenge therapy in patients with plasma RAS negative. Moreover, through biomarker analyses, our trial will shed light on which patients would benefit from rechallenge in addition to being plasma RAS negative.

TRIAL REGISTRATION

The REMARRY study: UMIN, UMIN000036424 . Registered date: April 5, 2019. The PURSUIT trial: jRCT, jRCTs031190096 . Registered date: October 1, 2019.

Heterogeneity of Colorectal Cancer Progression: Molecular Gas and Brakes

The review begins with molecular genetics, which hit the field unveiling the involvement of oncogenes and tumor suppressor genes in the pathogenesis of colorectal cancer (CRC) and uncovering genetic predispositions. Then the notion of molecular phenotypes with different clinical behaviors was introduced and translated in the clinical arena, paving the way to next-generation sequencing that captured previously unrecognized heterogeneity. Among other molecular regulators of CRC progression, the extent of host immune response within the tumor micro-environment has a critical position. Translational sciences deeply investigated the field, accelerating the pace toward clinical transition, due to its strong association with outcomes. While the perturbation of gut homeostasis occurring in inflammatory bowel diseases can fuel carcinogenesis, micronutrients like vitamin D and calcium can act as brakes, and we discuss underlying molecular mechanisms. Among the components of gut microbiota, Fusobacterium nucleatum is over-represented in CRC, and may worsen patient outcome. However, any translational knowledge tracing the multifaceted evolution of CRC should be interpreted according to the prognostic and predictive frame of the TNM-staging system in a perspective of clinical actionability. Eventually, we examine challenges and promises of pharmacological interventions aimed to restrain disease progression at different disease stages.

Biomarker-Guided Anti-Egfr Rechallenge Therapy in Metastatic Colorectal Cancer

Simple Summary

The survival of patients with metastatic colorectal cancer (mCRC) has been improved over the years and now reaches 30–40 months. However, few therapeutic options are available after failure of first- and second-line treatments. In fact, prognosis of chemo-refractory mCRC remains poor. Therefore, new therapeutic strategies are needed. Emerging evidence suggest that retreatment with epidermal growth factor (EGFR) inhibitors after a treatment break, in patients that obtained a clinical benefit by previous anti-EGFR, could lead to prolonged survival. The rationale beyond this “rechallenge” strategy is that after a “treatment holiday” EGFR resistant cancer cells decay, restoring the sensibility to EGFR blockade. In this review we analyze the current knowledge of retreatment with EGFR inhibitors, examine the role of novel biomarkers that can guide the appropriate selection of patients. Finally, we discuss future perspectives and on-going clinical trials.

Abstract

The prognosis of patients with metastatic colorectal cancer (mCRC) who progressed to the first and the second lines of treatment is poor. Thus, new therapeutic strategies are needed. During the last years, emerging evidence suggests that retreatment with anti-epidermal growth factor receptor (EGFR) monoclonal antibodies (MAbs) in the third line of mCRC patients, that have previously obtained clinical benefit by first-line therapy with anti-EGFR MAbs plus chemotherapy, could lead to prolonged survival. The rationale beyond this “rechallenge” strategy is that, after disease progression to first line EGFR-based therapy, a treatment break from anti-EGFR drugs results in RAS mutant cancer cell decay, restoring the sensitivity of cancer cells to cetuximab and panitumumab. In fact, rechallenge treatment with anti-EGFR drugs has shown promising clinical activity, particularly in patients with plasma RAS and BRAF wild type circulating tumor DNA, as defined by liquid biopsy analysis at baseline treatment. The aim of this review is to analyze the current knowledge on rechallenge and to investigate the role of novel biomarkers that can guide the appropriate selection of patients that could benefit from this therapeutic strategy. Finally, we discuss on-going trials and future perspectives.

Cell Surface GRP94 as a Novel Emerging Therapeutic Target for Monoclonal Antibody Cancer Therapy

Glucose-regulated protein 94 (GRP94) is an endoplasmic reticulum (ER)-resident member of the heat shock protein 90 (HSP90) family. In physiological conditions, it plays a vital role in regulating biological functions, including chaperoning cellular proteins in the ER lumen, maintaining calcium homeostasis, and modulating immune system function. Recently, several reports have shown the functional role and clinical relevance of GRP94 overexpression in the progression and metastasis of several cancers. Therefore, the current review highlights GRP94’s physiological and pathophysiological roles in normal and cancer cells. Additionally, the unmet medical needs of small chemical inhibitors and the current development status of monoclonal antibodies specifically targeting GRP94 will be discussed to emphasize the importance of cell surface GRP94 as an emerging therapeutic target in monoclonal antibody therapy for cancer.

Detection of Somatic Mutations with ddPCR from Liquid Biopsy of Colorectal Cancer Patients

Liquid biopsy and cell-free DNA (cfDNA) show great promise in cancer diagnostics. In this study, we designed a custom droplet digital PCR (ddPCR) assay for the quantification and quality control of cfDNA isolated from serum. The assay was validated on a group of locally advanced colorectal cancer (CRC) patients and two control groups-patients with hemorrhoids and healthy individuals. The assay shows a high correlation with Qubit measurement (r = 0.976) but offers a higher dynamic range. Mean concentrations of cfDNA were 12.36 ng/µL, 5.17 ng/µL, and 0.29 ng/µL for CRC, hemorrhoid patients, and healthy controls, respectively. The quality of cfDNA was assessed with the measurement of B-cell DNA contamination. On a subset of CRC patients, we compared the mutation status on KRAS (G12A, G12D, G12V, G13D) and BRAF (V600E) genes in the primary tumor and cfDNA isolated from the serum. A total of 70.6% of primary tumor samples were mutated, and the mean fractional abundance of mutations was 9.50%. The matching serum samples were mutated in 38% cases with an average fractional abundance of 0.23%. We conclude that any decisions based solely on the amount of cfDNA present in patient serum must be interpreted carefully and in the context of co-morbidities. This study explores the potential of ddPCR somatic mutations detection from liquid biopsy as a supplement to tissue biopsy in targeted personalized CRC patient management.