Endoscopic and imaging outcomes of PD-1 therapy in localised dMMR colorectal cancer

Long-Term Efficacy of Pembrolizumab and the Clinical Utility of ctDNA in Locally Advanced dMMR/MSI-H Solid Tumors

Neoadjuvant immunotherapy can induce pathologic complete response (pCR) in patients with localized deficient mismatch repair (dMMR)/microsatellite instability-high (MSI-H) tumors. The long-term outcomes of these patients are unknown, as is the clinical utility of measuring circulating tumor DNA (ctDNA). Follow-up was evaluated in patients enrolled in a phase II trial (NCT04082572) that evaluated the efficacy and safety of pembrolizumab in patients with localized dMMR/MSI-H tumors. The primary outcomes of this trial have previously been reported. 3-year EFS and OS rates were 80% (95% CI: 66% - 93%) and 94% (95% CI: 86% - 100%). Patients without detectable ctDNA after pembrolizumab had higher 3-year EFS and OS rates than patients with detectable ctDNA after pembrolizumab (3-year EFS 92% vs 20%; p < 0.001, 3-year OS 100% vs 80%; p < 0.001). Patients with colorectal cancer (CRC) who had undetectable ctDNA after pembrolizumab were more likely to have pCR compared to those with detectable ctDNA after pembrolizumab (91% vs 0%; p = 0.03). Patients with CRC who were managed non-operatively and had undetectable ctDNA after pembrolizumab had a higher 2-year EFS rate than patients with detectable ctDNA after pembrolizumab (100% vs 33%; p = 0.03). Pembrolizumab demonstrates long-term efficacy in patients with localized dMMR/MSI-H tumors.

Gastrointestinal tumor personalized immunotherapy: an integrated analysis from molecular genetics to imaging biomarkers

The immunotherapy landscape for gastrointestinal (GI) tumors is rapidly evolving. There is an urgent need for reliable biomarkers capable of predicting treatment outcomes to optimize therapeutic strategies and enhance patient prognosis. This review presents a comprehensive overview of biomarkers associated with the immunotherapy response of GI tumors, covering advances in molecular genetics, histopathological markers, and imaging. Key molecular biomarkers, such as microsatellite instability, tumor mutational burden, and programmed death-ligand 1 expression, remain critical for identifying patients likely to benefit from immune checkpoint inhibitors. The significance of tumor-infiltrating lymphocytes, notably the CD8+ T cell to regulatory T cell ratio, as a predictor of immunotherapy response is explored. In addition, advanced imaging techniques, including computed tomography (CT), magnetic resonance imaging, and positron emission tomography-CT, facilitate the noninvasive evaluation of tumor biology and therapeutic response. By bridging molecular and imaging data, this integrated strategy enhances precision in patient selection, treatment monitoring, and adaptive therapy design. Future studies should aim to validate these biomarkers in larger, multicenter cohorts and focus on clinical translation to advance precision medicine in GI oncology.

Colon cancer biology and treatment in the era of precision oncology: A primer for Radiologists

In the era of precision oncology, systemic therapies for colon cancer are becoming increasingly biomarker-led, with implications for patients in the neoadjuvant, adjuvant and metastatic settings. As the landscape for colon cancer treatment evolves and becomes more complex, it is important that all members of the multidisciplinary team keep abreast of developments to ensure the most effective care is delivered to patients. As core members of the colorectal multidisciplinary team, Radiologists play a central role throughout the patient journey. This review serves as an educational summary of current and emerging treatment pathways in colon cancer, standards for biomarker testing, mechanisms of action for key drugs, important treatment-related complications, relevant tumour biology that underpins patterns of disease and treatment response, and the specific implications systemic therapies have for cancer imaging and Radiologists. We also highlight the increasing role for radiology in patient stratification and the importance of imaging biomarkers. It is crucial that Radiologists understand the current landscape of colon cancer treatment and emerging strategies on the horizon in clinical trials. Only through engagement across the wider multidisciplinary team will we deliver true personalised medicine for patients with colon cancer.

Positive lateral lymph node turned negative after neoadjuvant therapy-surgery or observation?

Since the adoption of neoadjuvant chemoradiation and total mesorectal excision as the standard in rectal cancer care, there has been marked improvement in the local recurrence rates. In this context, restaging magnetic resonance imaging (MRI) plays a key role in the assessment of tumor response, occasionally enabling organ-sparing approaches. However, the role of restaging MRI in evaluating lateral lymph nodes remains limited. Most studies suggest a high risk of lateral local recurrence regardless of a decrease in lymph node size on restaging MRI. Therefore, it is recommended that clinical decisions should rely on the primary MRI scan. Watchful waiting may be appropriate only in cases of a clinical complete response with substantial downsizing of lateral lymph nodes (≤ 4.0 mm). Notably, some lateral lymph nodes may enlarge during follow-up despite complete tumor response, in which case, lateral lymph node dissection can be considered while preserving the rectum. Thus, continuous surveillance of lateral lymph nodes is essential during watchful waiting. Restaging MRI may hold greater importance for smaller lymph nodes (5.0-6.9 mm), as those with persistent malignant features on imaging carry a 13% risk of lateral recurrence at 4 years. Understanding these risks is critical when engaging in shared decision-making with the patient.

The efficacy and safety of neoadjuvant treatment with the PD-1 inhibitor for locally advanced colorectal cancer: a meta-analysis

Objective

To systematically evaluate the efficacy and safety of PD-1 inhibitors in neoadjuvant therapy for locally advanced colorectal cancer (LACRC).

Method

Retrieved from PubMed, Embase, and the Cochrane Library, all relevant studies about PD-1 inhibitors for neoadjuvant treatment of LACRC were collected from inception to 31 December 2023. The efficacy was assessed by the rate of pathological complete response (PCR), clinical complete response (CCR), and major pathological response (MPR), and the safety was evaluated by the incidence of all adverse effects (TRAEs). Subgroup analysis was conducted by experimental design, types of PD-1 inhibitors, and disease types.

Result

A total of 803 patients were included in 21 studies. The results of the meta-analysis showed that the PCR rate of PD-1 inhibitors in the treatment of LACRC was 54% (95% CI: 43%-65%, P<0.05); the CCR of anti-PD-1 was 40% (95% CI: 26%-54%, P<0.05); the MPR was 66% (95% CI: 56%-76%, P<0.05); and the irAEs was 27% (95% CI: 17%-37%, P<0.05). Subgroup analysis showed that the PCRs in prospective studies and retrospective studies were 49% (95% CI: 32%-66%, P<0.05) and 57% (95% CI: 42%-73%, P<0.05), respectively. Among the 803 patients, 619 (77%) were diagnosed with rectal cancer (RC), and the PCR and MPR were 49% and 65%, respectively; 184 (23%) were diagnosed with colorectal cancer (CRC), and the PCR and MPR were both 67%. In our meta-analysis, types of PD-1 inhibitors, including sintilimab, toripalimab, camrelizumab, avelumab, pembrolizumab, and tislelizumab, and patients who received PD-1 inhibitors alone or in combination achieved good PCR rates.

Conclusion

Neoadjuvant therapy combined with a PD-1 inhibitor has a favorable PCR and relatively low incidences of irAEs for patients with LACRC, suggesting that this regimen including a PD-1 inhibitor is significantly effective and sufficiently safe.

Randomized Phase II Trial of Immunotherapy-Based Total Neoadjuvant Therapy for Proficient Mismatch Repair or Microsatellite Stable Locally Advanced Rectal Cancer (TORCH)

PURPOSETo assess whether the integration of PD-1 inhibitor with total neoadjuvant therapy (iTNT) can lead to an improvement in complete responses (CRs) and favors a watch-and-wait (WW) strategy in patients with proficient mismatch repair or microsatellite stable (pMMR/MSS) locally advanced rectal cancer (LARC).PATIENTS AND METHODSWe conducted a prospective, multicenter, randomized, open-label, phase II trial using a pick-the-winner design. Eligible patients with clinical T3-4 and/or N+ rectal adenocarcinoma were randomly assigned to group A for short-course radiotherapy (SCRT) followed by six cycles of consolidation immunochemotherapy with capecitabine and oxaliplatin and toripalimab or to group B for two cycles of induction immunochemotherapy followed by SCRT and the rest four doses. Either total mesorectal excision or WW was applied on the basis of tumor response. The primary end point was CR which included pathological CR (pCR) after surgery and clinical CR (cCR) if WW was applicable, with hypothesis of an increased CR of 40% after iTNT compared with historical data of 25% after conventional TNT.RESULTSOf the 130 patients enrolled, 121 pMMR/MSS patients were evaluable (62 in group A and 59 in group B). At a median follow-up of 19 months, CR was achieved at 56.5% in group A and 54.2% in group B. Both groups fulfilled the predefined statistical hypothesis (P < .001). Both groups reported a pCR rate of 50%. Respectively, 15 patients in each group underwent WW and remained disease free. The most frequent grade 3 to 4 toxicities were thrombocytopenia and neutropenia. Patients in group A had higher rate of cCR (43.5% v 35.6%) at restaging and lower rate of grade 3 to 4 thrombocytopenia (24.2% v 33.9%) during neoadjuvant treatment.CONCLUSIONThe iTNT regimens remarkably improved CR rates in pMMR/MSS LARC compared with historical benchmark with acceptable toxicity. Up-front SCRT followed by immunochemotherapy was selected for future definitive study.

Improving individualised therapies in localised gastro-oesophageal adenocarcinoma

Despite our increased understanding of the biological and molecular aspects of gastro-oesophageal tumourigenesis, the identification of prognostic or predictive factors remains challenging. Patients with resectable gastric and oesophageal adenocarcinoma are often treated similarly after surgical resection, regardless of their tumour biology, clinical characteristics, and histological treatment response. Substantial progress has been made in the past 5 years in managing patients with gastric or oesophageal adenocarcinoma, including the use of immune checkpoint inhibitors and new targeted therapies, leading to substantial improvements in clinical outcomes. These advancements have primarily been established in advanced and metastatic disease, while the management framework for local and locoregional disease is just beginning to shift. We provide an overview of existing data on biomarkers and tumour-related and host-related factors that are relevant to stratify patients into low-risk and high-risk recurrence groups, both before and after surgery, paving the way for more personalised treatment approaches.

Can rectal MRI and endorectal ultrasound accurately predict the complete response to neoadjuvant immunotherapy for rectal cancer?

Background

Standardized assessments of clinical complete response (cCR) to neoadjuvant chemoradiotherapy (nCRT) for rectal cancer have been established, but their utility and accuracy remain unclear. This study aimed to evaluate the clinical diagnostic value of rectal magnetic resonance imaging (MRI) and endorectal ultrasonography (ERUS) for the determination of cCRs after neoadjuvant immunotherapy and to investigate the concordance between cCR and pathological complete response (pCR).

Methods

Ninety-four patients with rectal cancer treated with neoadjuvant radiotherapy with or without immunotherapy were included. The sensitivity, specificity, and accuracy of each evaluation method were calculated.

Results

Combined MRI and ERUS assessments found cCR in seven of the 94 patients in our cohort. In the non-immunotherapy group, the sensitivity, specificity, and accuracy of MRI for diagnosing cCR were 50.0%, 85.2%, and 77.1%, respectively, whereas those of ERUS were 50.0%, 92.6%, and 82.9%, respectively; those of combined MRI and ERUS were 25.0%, 96.3%, and 87.5%, respectively. In the immunotherapy group, the sensitivity, specificity, and accuracy with which MRI identified CR were 51.7%, 76.7%, and 64.4%, respectively; those of ERUS were 13.8%, 90.0%, and 52.5%, respectively, and those of combined MRI and ERUS were 10.3%, 96.7%, and 54.2%, respectively. We also found that 32 of 37 patients with pCR did not meet the cCR evaluation criteria. Of these pCR patients, 78.4% (29/37) received immunotherapy. In the entire cohort, there were five pCRs among the seven cCRs. Of the four cCRs that occurred in the immunotherapy group, three were pCRs.

Conclusions

Rectal MRI and/or ERUS did not provide sufficiently accurate assessments of cCR in patients with rectal cancer receiving neoadjuvant therapy, especially immunotherapy, and cCR did not predict pCR.