Consistent signatures in the human gut microbiome of old- and young-onset colorectal cancer

The incidence of young-onset colorectal cancer (yCRC) has been increasing in recent decades, but little is known about the gut microbiome of these patients. Most studies have focused on old-onset CRC (oCRC), and it remains unclear whether CRC signatures derived from old patients are valid in young patients. To address this, we assembled the largest yCRC gut metagenomes to date from two independent cohorts and found that the CRC microbiome had limited association with age across adulthood. Differential analysis revealed that well-known CRC-associated taxa, such as Clostridium symbiosum, Peptostreptococcus stomatis, Parvimonas micra and Hungatella hathewayi were significantly enriched (false discovery rate <0.05) in both old- and young-onset patients. Similar strain-level patterns of Fusobacterium nucleatum, Bacteroides fragilis and Escherichia coli were observed for oCRC and yCRC. Almost all oCRC-associated metagenomic pathways had directionally concordant changes in young patients. Importantly, CRC-associated virulence factors (fadA, bft) were enriched in both oCRC and yCRC compared to their respective controls. Moreover, the microbiome-based classification model had similar predication accuracy for CRC status in old- and young-onset patients, underscoring the consistency of microbial signatures across different age groups.

Long-Term Outcomes of dMMR/MSI-H Rectal Cancer Treated With Anti-PD-1-Based Immunotherapy as Curative-Intent Treatment

BACKGROUND

Neoadjuvant anti-PD-1 therapy has shown encouraging efficacy in patients with deficient DNA mismatch repair (dMMR)/microsatellite instability-high (MSI-H) locally advanced rectal cancer (LARC), which suggests its potential as a curative-intent therapy and a promising treatment option for organ preservation. We aimed to investigate the long-term outcomes of patients with dMMR/MSI-H LARC who experienced clinical complete response (cCR) after anti-PD-1 therapy.

METHODS

We retrospectively analyzed patients with dMMR/MSI-H LARC who achieved cCR and received nonoperative management following neoadjuvant anti-PD-1-based treatment from 4 Chinese medical centers. Patients were followed up for at least 1 year after they achieved cCR, their clinical data were collected, and survival outcomes were analyzed using the Kaplan-Meier method.

RESULTS

A total of 24 patients who achieved cCR and received nonoperative management from March 2018 to May 2022 were included, with a median age of 51.0 years (range, 19.0-77.0 years). The median treatment course to reach cCR was 6.0 (range, 1.0-12.0). Fifteen patients (62.5%) continued their treatments after experiencing cCR, and the median treatment course was 17.0 (range, 3.0-36.0). No local regrowth or distant metastasis was observed in a median follow-up time of 29.1 months (range, 12.6-48.5 months) after cCR. The 3-year disease-free and overall survivals were both 100%.

CONCLUSIONS

Patients with dMMR/MSI-H locally advanced or low-lying rectal cancer who achieved cCR following anti-PD-1-based therapy had promising long-term outcomes. A prospective clinical trial with a larger sample size is required to further validate these findings.

Efficacy of PD-1 inhibitors for colorectal cancer and polyps in Lynch syndrome patients

BACKGROUND

Programmed death-1 (PD-1) inhibitor is effective for colorectal cancer (CRC) with deficient mismatch repair (dMMR) or high microsatellite instability (MSI-H). We aimed to explore its effects on CRCs and colonic polyps in Lynch syndrome (LS) patients.

METHODS

LS patients with CRC who had evaluable tumours and received at least 2 cycles of PD-1 inhibitors were retrospectively included. PD-1 inhibitors were given as a monotherapy or in combination with other therapies, including anticytotoxic T-lymphocyte-associated antigen-4 treatment, radiotherapy, chemotherapy, and targeted therapy. Correlations of treatment responses with clinicopathological characteristics and genomic profiles were analysed.

RESULTS

A total of 75 LS patients were included, with a median age of 39 years. The median duration of follow-up was 27 months (range, 3-71). The objective response rate (ORR) was 70.7%, including 28.0% (n = 21) complete responses and 42.7% (n = 32) partial responses. Four of five cases of LS CRCs displaying proficient MMR (pMMR) or microsatellite stable (MSS) were not responsive. Mucinous/signet-ring cell differentiation was associated with a lower ORR (P = 0.013). The 3-year overall survival and progression-free survival were 91.2% and 82.2%, respectively. A polyp was detected in 26 patients during surveillance. Seven adenomas disappeared after treatment, and they were all larger than 7 mm.

CONCLUSION

PD-1 inhibitors are highly effective for dMMR and MSI-H LS CRCs, but not for pMMR or MSS LS CRCs or mucinous/signet-ring cell CRC. Large LS adenomas may also be eliminated by anti-PD-1 treatment.

DATA AVAILABILITY STATEMENT

Due to the privacy of patients, the related data cannot be available for public access but can be obtained from Pei-Rong Ding (dingpr@sysucc.org.cn) upon reasonable request. The key raw data have been uploaded to the Research Data Deposit public platform (www.researchdata.org.cn).

Neoadjuvant Chemotherapy With CAPOX Versus Chemoradiation for Locally Advanced Rectal Cancer With Uninvolved Mesorectal Fascia (CONVERT): Initial Results of a Phase III Trial

OBJECTIVE

To compare neoadjuvant chemotherapy (nCT) with CAPOX alone versus neoadjuvant chemoradiotherapy (nCRT) with capecitabine in locally advanced rectal cancer (LARC) with uninvolved mesorectal fascia (MRF).

BACKGROUND DATA

nCRT is associated with higher surgical complications, worse long-term functional outcomes, and questionable survival benefits. Comparatively, nCT alone seems a promising alternative treatment in lower-risk LARC patients with uninvolved MRF.

METHODS

Patients between June 2014 and October 2020 with LARC within 12 cm from the anal verge and uninvolved MRF were randomly assigned to nCT group with 4 cycles of CAPOX (Oxaliplatin 130 mg/m2 IV day 1 and Capecitabine 1000 mg/m2 twice daily for 14 d. Repeat every 3 wk) or nCRT group with Capecitabine 825 mg/m² twice daily administered orally and concurrently with radiation therapy (50 Gy/25 fractions) for 5 days per week. The primary end point is local-regional recurrence-free survival. Here we reported the results of secondary end points: histopathologic response, surgical events, and toxicity.

RESULTS

Of the 663 initially enrolled patients, 589 received the allocated treatment (nCT, n=300; nCRT, n=289). Pathologic complete response rate was 11.0% (95% CI, 7.8-15.3%) in the nCT arm and 13.8% (95% CI, 10.1-18.5%) in the nCRT arm ( P =0.33). The downstaging (ypStage 0 to 1) rate was 40.8% (95% CI, 35.1-46.7%) in the nCT arm and 45.6% (95% CI, 39.7-51.7%) in the nCRT arm ( P =0.27). nCT was associated with lower perioperative distant metastases rate (0.7% vs. 3.1%, P =0.03) and preventive ileostomy rate (52.2% vs. 63.6%, P =0.008) compared with nCRT. Four patients in the nCT arm received salvage nCRT because of local disease progression after nCT. Two patients in the nCT arm and 5 in the nCRT arm achieved complete clinical response and were treated with a nonsurgical approach. Similar results were observed in subgroup analysis.

CONCLUSIONS

nCT achieved similar pCR and downstaging rates with lower incidence of perioperative distant metastasis and preventive ileostomy compared with nCRT. CAPOX could be an effective alternative to neoadjuvant therapy in LARC with uninvolved MRF. Long-term follow-up is needed to confirm these results.

Neoadjuvant Immunotherapy Leads to Major Response and Low Recurrence in Localized Mismatch Repair-Deficient Colorectal Cancer

BACKGROUND

Our study aimed to evaluate the efficacy and feasibility of neoadjuvant anti-PD-1 treatment for localized mismatch repair-deficient (dMMR) colorectal cancer (CRC).

PATIENTS AND METHODS

The study cohort included patients with localized dMMR CRC who received PD-1 inhibitors as neoadjuvant therapy from 3 medical centers in Southern China. Main eligibility criteria included age between 18 and 75 years, ECOG performance status of 0 or 1, and receipt of ≥2 doses of PD-1 inhibitors.

RESULTS

A total of 73 patients were included. Most of the tumors were locally advanced, including 19 (26.0%) T4a and 29 (39.7%) T4b. Most patients (79.5%) received PD-1 inhibitor monotherapy. Objective response per radiologic assessment was achieved in 62 (84.9%) patients, including 17 (23.3%) with complete response (CR) and 45 (61.6%) with partial response, with a median time to response of 9.6 weeks. Patients with T4a/4b disease had a similar response rate as those with T2-3 disease (84.0% vs 85.4%; P=.999). As of writing, a total of 50 patients have undergone surgery. Pathologic CR was achieved in most (57.1%) patients and remained high (59.5%) even among the 38 patients with T4a/4b disease. The 17 patients with CR did not undergo surgery and adopted a watch-and-wait strategy. After a median follow-up of 17.2 months (range, 3.4-45.1 months), the overall median recurrence-free and overall survivals were not reached. Among patients undergoing surgery or achieving CR, the 2-year tumor-specific disease-free and overall survival rates were both 100%. During neoadjuvant treatment, grade 3-4 adverse events occurred in 8 patients; 4 required acute intervention. Severe postoperative complications were recorded in 4 patients, 3 of whom required a second surgery.

CONCLUSIONS

Neoadjuvant therapy with PD-1 blockade is highly effective for localized dMMR CRC, with an acceptable safety profile and low recurrence rate. This treatment holds promise for becoming the new standard of care for localized dMMR CRCs.

Clinicopathological characteristics of high microsatellite instability/mismatch repair-deficient colorectal cancer: A narrative review

Colorectal cancers (CRCs) with high microsatellite instability (MSI-H) and deficient mismatch repair (dMMR) show molecular and clinicopathological characteristics that differ from those of proficient mismatch repair/microsatellite stable CRCs. Despite the importance of MSI-H/dMMR status in clinical decision making, the testing rates for MSI and MMR in clinical practice remain low, even in high-risk populations. Additionally, the real-world prevalence of MSI-H/dMMR CRC may be lower than that reported in the literature. Insufficient MSI and MMR testing fails to identify patients with MSI-H/dMMR CRC, who could benefit from immunotherapy. In this article, we describe the current knowledge of the clinicopathological features, molecular landscape, and radiomic characteristics of MSI-H/dMMR CRCs. A better understanding of the importance of MMR/MSI status in the clinical characteristics and prognosis of CRC may help increase the rates of MMR/MSI testing and guide the development of more effective therapies based on the unique features of these tumors.

Clinical actionability of triaging DNA mismatch repair deficient colorectal cancer from biopsy samples using deep learning

Background

We aimed to develop a deep learning (DL) model to predict DNA mismatch repair (MMR) status in colorectal cancers (CRC) based on hematoxylin and eosin-stained whole-slide images (WSIs) and assess its clinical applicability.

Methods

The DL model was developed and validated through three-fold cross validation using 441 WSIs from the Cancer Genome Atlas (TCGA) and externally validated using 78 WSIs from the Pathology AI Platform (PAIP), and 355 WSIs from surgical specimens and 341 WSIs from biopsy specimens of the Sun Yet-sun University Cancer Center (SYSUCC). Domain adaption and multiple instance learning (MIL) techniques were adopted for model development. The performance of the models was evaluated using the area under the receiver operating characteristic curve (AUROC). A dual-threshold strategy was also built from the surgical cohorts and validated in the biopsy cohort. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), F1-score, and the percentage of patients avoiding IHC testing were evaluated.

Findings

The MIL model achieved an AUROC of 0·8888±0·0357 in the TCGA-validation cohort, 0·8806±0·0232 in the PAIP cohort, 0·8457±0·0233 in the SYSUCC-surgical cohort, and 0·7679±0·0342 in the SYSUCC-biopsy cohort. A dual-threshold triage strategy was used to rule-in and rule-out dMMR patients with remaining uncertain patients recommended for further IHC testing, which kept sensitivity higher than 90% and specificity higher than 95% on deficient MMR patient triage from both the surgical and biopsy specimens, result in more than half of patients avoiding IHC based MMR testing.

Interpretation

A DL-based method that could directly predict CRC MMR status from WSIs was successfully developed, and a dual-threshold triage strategy was established to minimize the number of patients for further IHC testing.

Funding

The study was funded by the National Natural Science Foundation of China (82073159, 81871971 and 81700576), the Natural Science Foundation of Guangdong Province (No. 2021A1515011792 and No.2022A1515012403) and Medical Scientific Research Foundation of Guangdong Province of China (No. A2020392).