Microsatellite instability at U2AF-binding polypyrimidic tract sites perturbs alternative splicing during colorectal cancer initiation.

BACKGROUND: Microsatellite instability (MSI) due to mismatch repair deficiency (dMMR) is common in colorectal cancer (CRC). These cancers are associated with somatic coding events, but the noncoding pathophysiological impact of this genomic instability is yet poorly understood. Here, we perform an analysis of coding and noncoding MSI events at the different steps of colorectal tumorigenesis using whole exome sequencing and search for associated splicing events via RNA sequencing at the bulk-tumor and single-cell levels. RESULTS: Our results demonstrate that MSI leads to hundreds of noncoding DNA mutations, notably at polypyrimidine U2AF RNA-binding sites which are endowed with cis-activity in splicing, while higher frequency of exon skipping events are observed in the mRNAs of MSI compared to non-MSI CRC. At the DNA level, these noncoding MSI mutations occur very early prior to cell transformation in the dMMR colonic crypt, accounting for only a fraction of the exon skipping in MSI CRC. At the RNA level, the aberrant exon skipping signature is likely to impair colonic cell differentiation in MSI CRC affecting the expression of alternative exons encoding protein isoforms governing cell fate, while also targeting constitutive exons, making dMMR cells immunogenic in early stage before the onset of coding mutations. This signature is characterized by its similarity to the oncogenic U2AF1-S34F splicing mutation observed in several other non-MSI cancer. CONCLUSIONS: Overall, these findings provide evidence that a very early RNA splicing signature partly driven by MSI impairs cell differentiation and promotes MSI CRC initiation, far before coding mutations which accumulate later during MSI tumorigenesis.

Trastuzumab deruxtecan in patients with HER2-positive advanced colorectal cancer (DESTINY-CRC02): primary results from a multicentre, randomised, phase 2 trial.

BACKGROUND: Trastuzumab deruxtecan has shown encouraging activity in patients with treatment-refractory HER2-positive, RAS wild-type and BRAF wild-type metastatic colorectal cancer. Dose optimisation and further antitumour assessments in patients with RAS mutations and those with previous anti-HER2 therapy are warranted. We aimed to evaluate two doses of trastuzumab deruxtecan (5·4 mg/kg and 6·4 mg/kg) to establish the recommended dose in patients with pretreated HER2-positive, RAS wild-type or mutant metastatic colorectal cancer. METHODS: DESTINY-CRC02 was a multicentre, randomised, two-stage, two-arm, phase 2 study done in 53 research hospitals and medical centres in Australia, Belgium, France, Italy, Japan, South Korea, Spain, Taiwan, the UK, and the USA. Eligible patients were aged 18 years and older or 20 years and older (depending on region) with pretreated pathologically documented, unresectable, recurrent, or metastatic HER2-positive, and RAS wild-type or mutant colorectal cancer. Patients were required to have an Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1 and have received previous chemotherapy, and anti-EGFR, anti-VEGF, or anti-PD-L1 therapy, if clinically indicated. In stage 1, patients were randomly assigned (1:1), via a secure interactive response technology system, to receive 5·4 mg/kg or 6·4 mg/kg trastuzumab deruxtecan administered intravenously every 21 days. Stratification factors were ECOG performance status, HER2 status, and RAS status. In stage 2, patients were assigned into the 5·4 mg/kg treatment group only. The primary endpoint was confirmed objective response rate by blinded independent central review, assessed in all patients for whom treatment was assigned (full analysis set). Safety was assessed in all patients who received at least one dose of study drug. This trial is registered with ClinicalTrials.gov, NCT04744831, and is ongoing (not recruiting). FINDINGS: Between March 5, 2021, and March 29, 2022, 135 patients were centrally screened, 122 of whom were enrolled. In stage 1, 40 patients each were randomly assigned to receive trastuzumab deruxtecan 5·4 mg/kg and 6·4 mg/kg. In stage 2, an additional 42 patients were enrolled in the 5·4 mg/kg group. 64 (52%) participants were male and 58 (48%) were female. The median duration of follow-up was 8·9 months (IQR 6·7-10·5) in the 5·4 mg/kg group and 10·3 months (5·9-12·7) in the 6·4 mg/kg group. The confirmed objective response rate by blinded independent central review was 37·8% (31/82 [95% CI 27·3-49·2]) in the 5·4 mg/kg group and 27·5% (11/40 [14·6-43·9]) in the 6·4 mg/kg group. 34 (41%) of 83 patients in the 5·4 mg/kg group and 19 (49%) of 39 in the 6·4 mg/kg group had grade 3 or worse drug-related treatment-emergent adverse events. The most common grade 3 or worse drug-related treatment-emergent adverse events were neutrophil count decreased (13 [16%] of 83 patients), anaemia (six [7%]), nausea (six [7%]), and white blood cell count decreased (five [6%]) in the 5·4 mg/kg group; and were neutrophil count decreased (10 [26%] of 39 patients), anaemia (eight [21%]), platelet count decreased (four [10%]), and white blood cell count decreased (four [10%]) in the 6·4 mg/kg group. Drug-related serious adverse events occurred in 11 (13%) of 83 patients in the 5·4 mg/kg group and six (15%) of 39 patients in the 6·4 mg/kg group; the most common in the 5·4 mg/kg group was nausea (three [4%] patients) and the most common in the 6·4 mg/kg group were fatigue (two [5%] patients), neutropenia (two [5%]), and thrombocytopenia (two [5%]). A drug-related treatment-emergent adverse event related to death occurred in one (1%) patient in the 5·4 mg/kg group (due to hepatic failure). Adjudicated drug-related interstitial lung disease or pneumonitis events were observed in seven (8%) patients in the 5·4 mg/kg group (all grade 1 or 2) and in five (13%) patients in the 6·4 mg/kg group (four grade 1 or 2; one grade 5). INTERPRETATION: The promising antitumour activity and favourable safety profile support trastuzumab deruxtecan 5·4 mg/kg as the optimal single-agent dose for patients with pretreated HER2-positive metastatic colorectal cancer, including those with RAS mutations, previous anti-HER2 therapy, or both. FUNDING: Daiichi Sankyo and AstraZeneca.

A novel risk classification model integrating CEA, ctDNA, and pTN stage for stage 3 colon cancer: a post hoc analysis of the IDEA-France trial.

BACKGROUND: We assessed the added value of incorporating carcinoembryonic antigen (CEA) to circulating tumor DNA (ctDNA) and pathological TN (pTN) stage for risk classification in stage 3 colon cancer (CC). PATIENTS AND METHODS: We retrospectively analyzed postoperative CEA values in patients with CC from the IDEA-France phase 3 trial. The relation between disease-free survival (DFS) and CEA was modeled through restricted cubic splines. Prognostic value of CEA, ctDNA, and pTN was assessed with the Kaplan-Meier method. Multivariate analysis was used to identify prognostic and predictive factors for DFS. RESULTS: Among 696 patients (35%), CEA values were retrievable, and for 405 (20%) both CEA and ctDNA were available. An optimized CEA threshold of 2 ng/mL was identified, the 3-year DFS was 66.4% for patients above the threshold and 80.9% for those below (HR, 1.74; 95% CI, 1.33-2.28, P < .001). In multivariate analysis, CEA ≥ 2 ng/mL contributed significantly to model variability, becoming an independent prognostic factor for DFS (HR, 1.82; 95% CI,1.27-2.59), alongside ctDNA (HR, 1.88; 95% CI, 1.16-3.03) and pTN (HR, 1.78; 95% CI, 1.24-2.54). A novel integrated risk classification combining CEA, ctDNA, and pTN stage reclassified 19.8% of pT4/N2 patients as low risk and 2.5% of pT3/N1 patients as high risk. This new classification demonstrated the 3-year DFS of 80.8% for low-risk patients and 55.4% for high-risk patients (HR, 2.66, 95% CI, 1.84-3.86, P < .001). CONCLUSIONS: Postoperative CEA value is a prognostic factor for DFS in stage 3 CC, independently of ctDNA and pTN. It advocates for systematic reporting in future adjuvant trials. Integrating both biomarkers with pTN could refine risk classification in stage 3 CC.

Survival Outcomes in Patients with Monobloc-Resected Stage IIC (pT4bN0) Colon Cancer: A Retrospective Observational Cohort Study.

BACKGROUND: Stage II colon cancer (CC) exhibits considerable prognostic heterogeneous. Our objective was to assess survival but also the prognosis impact of microsatellite instability (MSI) in patients with stage IIC (T4bN0M0) CC. PATIENTS AND METHODS: We conducted a retrospective observational study including all patients who had primary stage IIC CC resection between 2010 and 2020 in 2 expert centers. The primary endpoint was overall survival (OS) and disease-free survival (DFS) and time-to-relapse (TTR) were secondary endpoints. RESULTS: Sixty-six patients, median age of 74 years [30-95], were included, with 37.9% presenting MSI (n = 25). Organ invasion involved the last ileal loop (n = 17), another colonic segment (n = 15), omentum (n = 13), visceral peritoneum (n = 13), and the bladder (n = 4). Surgical quality criteria showed complete monobloc resection in all patients and 93.9% R0 resection. After a median follow-up of 5 years [3.5-6.6], the entire population showed a 5-year OS of 65.2% [53.0-80.3] and 5-year DFS of 53.5% [41.1-69.6], with 18.9% [6.8-29.4] experiencing relapses at 5 years. The MSI phenotype correlated with improved 5-year OS (75.5% [56.5-100] vs. 59.5% [44.9-79.0], HR 0.41 [0.17-0.99]; P = .04), but DFS and TTR did not differ. Adjuvant chemotherapy was administered to 34.9% of patients. Univariate analysis identified age > 65 years, MSI status, and the number of nodes as factors associated with OS. CONCLUSION: These data underline, in relation to a low rate of relapse, the lack of consensus regarding the appropriate indication for adjuvant chemotherapy in this high-risk stage II population.

Prognostic value of liver metastases in colorectal cancer treated by systemic therapy: An ARCAD pooled analysis.

BACKGROUND: The liver is the most frequent site of metastases in colorectal cancer (CRC). This study aimed to assess the response rate and survival outcomes in metastatic CRC patients with non-liver metastases (NLM) compared to those with liver metastases (LM) across different lines of treatment. METHODS: A total of 17,924 mCRC patients included in 26 trials from the ARCAD CRC database were analyzed. The analysis was conducted based on the presence or absence of LM across different treatment groups: chemotherapy (CT) alone, CT + anti-VEGF, CT + anti-EGFR in KRAS wild-type tumors, within the first-line (1 L) and second-line (2 L), and patients enrolled in third-line (≥3 L) trials treated with trifluridine/tipiracil or regorafenib or placebo. The endpoints were overall survival (OS), progression-free survival (PFS), and overall response rate (ORR). RESULTS: Out of the 17,924 patients, 14,066 had LM (30.6 % with only liver involvement and 69.4 % with liver and other metastatic sites), while 3858 patients had NLM. In the CT alone and CT + anti-VEGF subgroups, NLM patients showed better OS and PFS in the 1 L and 2 L settings. However, in the CT + anti-EGFR 1 L and 2 L subgroups, there was no significant difference in OS and PFS between NLM and LM patients. In the ≥ 3 L subgroups, better OS and PFS were observed in NLM patients. ORRs were higher in LM patients than in NLM patients across all cohorts treated in the 1 L and only in the anti-EGFR cohort in the 2 L. CONCLUSION: LM is a poor prognostic factor for mCRC increasing from 1 L to ≥ 3 L except for patients in 1 L and 2 L receiving CT+anti-EGFR. These data justify using LM as a stratification factor in future trials for patients with unresectable mCRC.

Standardizing data collection in adjuvant colon cancer trials: A consensus project from the IDEA and ACCENT international consortia and national experts.

BACKGROUND: Despite contributions provided by the recent clinical trials, several issues and challenges still remain unsolved in adjuvant colon cancer (CC). Hence, further studies should be planned to better refine risk assessment as well as to establish the optimal treatment strategy in the adjuvant setting. However, it is necessary to request adequate, contemporary and relevant variables and report them homogeneously in order to bring maximal information when analyzing their prognostic value. MATERIAL AND METHODS: The project was devised to gain a consensus from experts engaged in the planning, accrual and analyses of stage II and III CC clinical trials, to identify mandatory and recommended baseline variables in order to i) harmonize future data collection worldwide in clinical trials dedicated to adjuvant treatment of CC; ii) propose guidance for Case Report Forms to be used for clinical trials in this setting. A total of 72 questions related to variables that should be reported and how to report them in adjuvant clinical trials were approved and then voted to reach a final consensus from panelists. RESULTS: Data items on patient-related factors, histopathological features, molecular profile, circulating biomarkers and blood analyses were analyzed and discussed by the whole expert panel. For each item, we report data supporting the acquired consensus and the relevant issues that were discussed. Nineteen items were deemed to be mandatory for resected stage III patients and 24 for resected stage II disease. In addition, 9 and 4 items were judged as recommended for stage III and II, respectively. CONCLUSION: In our opinion, these 28 variables should be used and uniformly reported in more comprehensive CRFs as research groups design future clinical trials in the field of adjuvant colon cancer.

The Prognostic Nutritional Index in patients with microsatellite instability-high metastatic gastric or gastroesophageal cancers receiving immune checkpoint inhibitors.

BACKGROUND: Microsatellite instability high (MSI-H) and/or mismatch repair deficient (dMMR) status is the strongest predictive factor for immune checkpoint inhibitors (ICIs) benefit in patients with metastatic gastroesophageal cancer (mGC). Primary resistance to ICIs is a relevant issue, but prognostic and predictive factors are lacking. MATERIALS AND METHODS: In this multinational, retrospective cohort of patients with MSI-H/dMMR mGC treated with ICIs without chemotherapy we collected baseline laboratory values to establish the prognostic nutritional index (PNI). We evaluated the association between baseline PNI with the activity and efficacy of ICIs. RESULTS: At a median follow-up of 31.6 months, median progression-free survival (PFS) and 2-year PFS rate were not reached and 73.6 % in the PNI-high subgroup versus 6.3 months and 38.3 % in the PNI-low one (HR 0.32, 95 % CI: 0.16-0.61, p < .001). Median overall survival (OS) and 2-year OS rate were not reached and 81.9 % in the PNI-high subgroup versus 24.4 months and 50.5 % in the PNI-low one (HR 0.26, 95 % CI: 0.12-0.56, p < .001). In multivariable models, high PNI was associated with longer PFS and OS (HR 0.30, 95 % CI: 0.15-0.61, p <0.001 and 0.37, 95 % CI: 0.15-0.91, p = .031). CONCLUSIONS: High PNI is associated with longer PFS and OS, in patients with MSI-H mGC receiving ICIs. Patients with low baseline PNI may benefit from intensive therapeutic approaches.

Wnt, glucocorticoid and cellular prion protein cooperate to drive a mesenchymal phenotype with poor prognosis in colon cancer.

BACKGROUND: The mesenchymal subtype of colorectal cancer (CRC), associated with poor prognosis, is characterized by abundant expression of the cellular prion protein PrPC, which represents a candidate therapeutic target. How PrPC is induced in CRC remains elusive. This study aims to elucidate the signaling pathways governing PrPC expression and to shed light on the gene regulatory networks linked to PrPC. METHODS: We performed in silico analyses on diverse datasets of in vitro, ex vivo and in vivo models of mouse CRC and patient cohorts. We mined ChIPseq studies and performed promoter analysis. CRC cell lines were manipulated through genetic and pharmacological approaches. We created mice combining conditional inactivation of Apc in intestinal epithelial cells and overexpression of the human prion protein gene PRNP. Bio-informatic analyses were carried out in two randomized control trials totalizing over 3000 CRC patients. RESULTS: In silico analyses combined with cell-based assays identified the Wnt-ß-catenin and glucocorticoid pathways as upstream regulators of PRNP expression, with subtle differences between mouse and human. We uncover multiple feedback loops between PrPC and these two pathways, which translate into an aggravation of CRC pathogenesis in mouse. In stage III CRC patients, the signature defined by PRNP-CTNNB1-NR3C1, encoding PrPC, ß-catenin and the glucocorticoid receptor respectively, is overrepresented in the poor-prognosis, mesenchymal subtype and associates with reduced time to recurrence. CONCLUSIONS: An unleashed PrPC-dependent vicious circle is pathognomonic of poor prognosis, mesenchymal CRC. Patients from this aggressive subtype of CRC may benefit from therapies targeting the PRNP-CTNNB1-NR3C1 axis.

Imaging-guided prognostic score-based approach to assess the benefits of combotherapy versus monotherapy with immune checkpoint inhibitors in metastatic MSI-H colorectal cancer patients.

BACKGROUND: This retrospective study determined survival responses to immune checkpoint inhibitors (ICIs), comparing mono- (mono) and combo-immunotherapy (combo) in patients with microsatellite instability-high (MSI-H) metastatic colorectal cancer (mCRC) by analyzing quantitative imaging data and clinical factors. METHODS: One hundred fifty patients were included from two centers and divided into training (n = 105) and validation (n = 45) cohorts. Radiologists manually annotated chest-abdomen-pelvis computed tomography and calculated tumor burden. Progression-free survival (PFS) was assessed, and variables were selected through Recursive Feature Elimination. Cutoff values were determined using maximally selected rank statistics to binarize features, forming a risk score with hazard ratio-derived weights. RESULTS: In total, 2258 lesions were annotated with excellent reproducibility. Key variables in the training cohort included: total tumor volume (cutoff: 73 cm3), lesion count (cutoff: 20), age (cutoff: 60) and the presence of peritoneal carcinomatosis. Their respective weights were 1.13, 0.96, 0.91, and 0.38, resulting in a risk score cutoff of 1.36. Low-score patients showed similar overall survival and PFS regardless of treatment, while those with a high-score had significantly worse survivals with mono vs combo (P = 0.004 and P = 0.0001). In the validation set, low-score patients exhibited no significant difference in overall survival and PFS with mono or combo. However, patients with a high-score had worse PFS with mono (P = 0.046). CONCLUSIONS: A score based on total tumor volume, lesion count, the presence of peritoneal carcinomatosis, and age can guide MSI-H mCRC treatment decisions, allowing oncologists to identify suitable candidates for mono and combo ICI therapies.

A multicenter study evaluating efficacy of immune checkpoint inhibitors in advanced non-colorectal digestive cancers with microsatellite instability.

BACKGROUND: One randomized phase III trial comparing chemotherapy (CT) with immune checkpoint inhibitors (ICI) has demonstrated significant efficacy of ICI in deficient DNA mismatch repair system/microsatellite instability-high (dMMR/MSI-H) metastatic colorectal cancer. However, few studies have compared ICI with CT in other advanced dMMR/MSI-H digestive tumors. METHODS: In this multicenter study, we included patients with advanced dMMR/MSI-H non-colorectal digestive tumors treated with chemotherapy and/or ICIs. Patients were divided retrospectively into two groups, a CT group and an immunotherapy (IO) group. The primary endpoint was progression-free survival (PFS). A propensity score approach using the inverse probability of treatment weighting (IPTW) method was applied to deal with potential differences between the two groups. RESULTS: 133 patients (45.1/27.1/27.8% with gastric/small bowel/other carcinomas) were included. The majority of patients received ICI in 1st (29.1%) or 2nd line (44.4%). The 24-month PFS rates were 7.9% in the CT group and 71.2% in the IO group. Using the IPTW method, IO treatment was associated with better PFS (HR=0.227; 95% CI 0.147-0.351; p < 0.0001). The overall response rate was 26.3% in the CT group versus 60.7% in the IO group (p < 0.001) with prolonged duration of disease control in the IO group (p < 0.001). In multivariable analysis, predictive factors of PFS for patients treated with IO were good performance status, absence of liver metastasis and prior primary tumor resection, whereas no association was found for the site of the primary tumor. CONCLUSIONS: In the absence of randomized trials, our study highlights the superior efficacy of ICI compared with standard-of-care therapy in patients with unresectable or metastatic dMMR/MSI-H non-colorectal digestive cancer, regardless of tumor type, with acceptable toxicity.

Oxaliplatin-Based Adjuvant Chemotherapy in Older Patients With Stage III Colon Cancer: An ACCENT/IDEA Pooled Analysis of 12 Trials.

PURPOSE: A number of studies suggest that older patients may have reduced or no benefit from the addition of oxaliplatin to fluoropyrimidines as adjuvant chemotherapy for stage III colon cancer (CC). MATERIALS AND METHODS: We studied the prognostic impact of age, as well as treatment adherence/toxicity patterns according to age, in patients with stage III CC who received 3 or 6 months of infusional fluorouracil, leucovorin, and oxaliplatin/capecitabine and oxaliplatin (CAPOX) on the basis of data collected from trials from the ACCENT and IDEA databases. Associations between age and time to recurrence (TTR), disease-free survival (DFS), overall survival (OS), survival after recurrence (SAR), and cancer-specific survival (CSS) were assessed by a Cox model or a competing risk model, stratified by studies and adjusted for sex, performance status, T and N stage, and year of enrollment. RESULTS: A total of 17,909 patients were included; 24% of patients were age older than 70 years (n = 4,340). Patients age ≥70 years had higher rates of early treatment discontinuation. Rates of grade ≥3 adverse events were similar between those older and younger than 70 years, except for diarrhea and neutropenia that were more frequent in older patients treated with CAPOX (14.2% v 11.2%; P = .01 and 12.1% v 9.6%; P = .04, respectively). In multivariable analysis, TTR was not significantly different between patients <70 years and those ≥70 years, but DFS, OS, SAR, and CSS were significantly shorter in those patients ≥70 years. CONCLUSION: In patients ≥70 years with stage III CC fit enough to be enrolled in clinical trials, oxaliplatin-based adjuvant chemotherapy was well tolerated and led to similar TTR compared with younger patients, suggesting similar efficacy. TTR may be a more appropriate end point for efficacy in this patient population.

[An update on total neoadjuvant treatment of adenocarcinoma of the rectum]. / Actualisation des données sur le traitement néoadjuvant total de l'adénocarcinome du rectum.

A major advance has been made in the management of rectal cancer, with the emergence in 2021 of total neoadjuvant treatment. The main publications from the RAPIDO and PRODIGE-23 trials reported a significant improvement in progression-free survival and the pathological complete response rate. The aim of this review is to synthesize recent data on neoadjuvant treatment of rectal cancer, to explain the long-term results of the RAPIDO and PRODIGE-23 trials, and to put them into perspective, considering current advances in de-escalation strategies. The update of the 5-year survival data from the RAPIDO trial highlights an increased risk of loco-regional relapse, with 11.7% of relapses in the experimental group and 8.1% in the control group, while the update of the PRODIGE-23 trial confirms the benefits of this treatment regimen, with a significant improvement in overall survival. In addition, the results of the OPRA and PROPSPECT trials confirm the benefit of total neoadjuvant treatment with induction chemotherapy, as well as the possibility of surgical de-escalation in the OPRA trial and radiotherapy in the PROSPECT trial. The challenge for the future is to identify patients who require total neoadjuvant treatment with the aim of curative surgery to obtain a cure without local or distant relapse, and those for whom therapeutic de-escalation can be envisaged.

Safety profile of pembrolizumab monotherapy based on an aggregate safety evaluation of 8937 patients.

BACKGROUND: Pembrolizumab has a manageable safety profile as described in its label, which was primarily based on 2799 patients who participated in clinical trials for melanoma or non-small cell lung cancer. Here, we evaluated the safety of pembrolizumab in a broader population of patients from 31 advanced cancer clinical trials across 19 cancer types. METHODS: Safety was analyzed in patients who received at least one dose of pembrolizumab (200 mg every 3 weeks [Q3W], 10 mg/kg Q2W or Q3W, or 2 mg/kg Q3W). Adverse events (AEs) and immune-mediated AEs and infusion reactions were evaluated. RESULTS: Safety data from 8937 patients in 31 trials of pembrolizumab monotherapy were pooled (median, seven administrations; range, 1-59). Median duration on treatment was 4.1 months (range, 0.03-40.1). AEs occurred in 96.6% of patients. Grade 3-5 AEs occurred in 50.6% of patients. AEs led to pembrolizumab discontinuation in 12.7% of patients and death in 5.9%. Immune-mediated AEs and infusion reactions occurred in 23.7% of patients (4.6% experienced multiple immune-mediated AEs/infusion reactions) and led to pembrolizumab discontinuation in 3.6% and death in 0.2%. Grade 3-5 immune-mediated AEs occurred in 6.3% of patients. Serious immune-mediated AEs and infusion reactions occurred in 6.0% of patients. Median time to immune-mediated AE onset was 85 days (range, 13-163). Of 2657 immune-mediated AEs, 22.3% were initially treated with prednisone ≥ 40 mg/day or equivalent, and 8.3% were initially treated with lower steroid doses. CONCLUSIONS: This pooled analysis of 31 clinical trials showed that pembrolizumab has a consistent safety profile across indications.

Efficacy of immune checkpoint inhibitors for metastatic colorectal cancer with microsatellite instability in second or latter line using synthetic control arms: A non-randomised evaluation.

PURPOSE: Immune checkpoint inhibitors (ICIs) appeared active in single-arm trials for patients with chemoresistant metastatic colorectal cancer (mCRC) harboring microsatellite instability (MSI). Given the paucity of randomised controlled trials (RCTs) in this setting, we evaluated the effect size of ICIs using intra-patients comparison and ARCAD database as historical controls. PATIENTS AND METHODS: Individual-patient data from NIPICOL and CheckMate 142 phase II trials that evaluated a combination of ICIs for MSI mCRC patients (N = 176) and from five non-ICI mCRC historical RCTs in second-line or latter (N = 4026) were analyzed. Firstly, promising of ICIs was identified using intra-patient comparison based on growth modulation index (GMI) defined the ratio of progression-free survivals (PFS) on ICIs and previous line of therapy. Survival outcomes of ICIs-treated patients were then compared with those matched non-ICIs treated from ARCAD database historical RCTs. RESULTS: Among ICIs-treated patients, median PFS on ICIs was 32.66 (range 0.10-74.25) versus 4.07 months (range 0.7-49.87) on prior therapy, resulting on median GMI of 4.97 (range 0.07-59.51; hazard-ratio (HR)= 0.16 (95 %CI=0.11-0.22, P < 0.001)). Compared to matched non-ICI patients, in third-line, median overall survival (OS) was not reached with ICIs versus 3.52 months with placebo (HR=0.20, 95 %CI=0.10-0.41, P < 0.001), and 6.51 months with active drugs (HR=0.30, 95 %CI=0.15-0.60, P = 0.001). In second-line, median OS was not reached with ICIs versus 11.7 months with chemotherapy+placebo (HR=0.12, 95 %CI=0.07-0.22, P < 0.001), and 16.3 months with chemotherapy+targeted therapy (HR=0.10, 95 %CI=0.05-0.19, P < 0.001). CONCLUSION: ICIs demonstrates high effect size for MSI mCRC patients in second-line and later. This work might be useful as an example of methodology to avoid RCTs when benefit from experimental therapy is likely to be high.

Deficient mismatch repair/microsatellite unstable colorectal cancer: therapeutic advances and questions.

The microsatellite instability (MSI) phenotype is related to a deficiency of the DNA mismatch repair (dMMR) system and is observed in 5% of metastatic colorectal cancers (mCRCs). MSI/dMMR phenotype testing should be routine for all CRCs regardless of stage. Two complementary techniques with a high concordance (90-97%) allow us to determine the MSI/dMMR status of a tumor: immunohistochemistry and polymerase chain reaction. Since 2020 and the results of the phase III KEYNOTE 177 trial, pembrolizumab [anti-programmed cell death protein 1 (PD1)] is the new standard of care in first-line MSI/dMMR mCRC. To date, no combination of chemtotherapy ± targeted therapy with immune checkpoint inhibitors (ICIs) has been validated in the management of MSI/dMMR mCRC, and it is not known whether this combination would be beneficial. It is also unclear whether dual therapy with two ICIs is more effective than monotherapy. Several phase III trials are ongoing to answer these questions. Despite a high response rate and long-term benefit of a first line by anti-PD1, 30-50% of patients with MSI/dMMR mCRC experience an early or secondary progression. There are currently no validated predictive biomarkers of anti-PD1 ± anti-cytotoxic T lymphocyte antigen-4 resistance in patients with MSI/dMMR mCRC. In case of early progression on ICIs, the first two questions to consider are the possibility of pseudoprogression and the correct diagnosis of MSI/dMMR status. To date, there are no data on the use of adjuvant ICIs for MSI/dMMR resected colon cancers. By contrast, data are accumulating regarding the efficacy of neoadjuvant ICIs, with at least two-thirds of patients in the different trials in pathological complete response, making it possible to envisage 'Watch and wait' strategies in future.