Dataset Information

Good Tumor Response to Chemoradioimmunotherapy in dMMR/MSI-H Advanced Colorectal Cancer: A Case Series.

ABSTRACT:

Purpose

Immune checkpoint blockade has led to a significant improvement of patient survival in metastatic colorectal cancer (CRC) with DNA mismatch repair-deficiency (dMMR)/microsatellite instability-high (MSI-H). However, not all these patients are sensitive to monoimmunotherapy. We firstly presented a case series of advanced dMMR/MSI-H CRCs treating with PD-1 inhibitor-based chemoradioimmunotherapy (CRIT).

Methods and materials

We assessed the short-term efficacy and safety of CRIT in advanced dMMR/MSI-H CRCs, and also did next-generation sequencing (NGS) assays.

Results

Our analysis included five advanced dMMR/MSI-H CRCs who have received toripalimab-based CRIT. Toripalimab was given 240mg every three weeks, and the radiation dose was 45-50 gray in 25 fractions. Chemotherapy regimens consisted of CAPOX in three patients, capecitabine in one patient, and mFOLFOX6 in one patient. Initially, two patients displayed complete response (CR), and three patients achieved partial response (PR) on imaging findings. Afterwards, one PR patient was confirmed pathological complete response after surgery, leading to three CR cases in total. Hematological toxicity was the most common adverse effect, and only two patients developed mild immune-related adverse effects besides. All the treatment-related adverse events were under control. Based on the NGS results, the median intratumor heterogeneity was 0.19 (range 0-0.957), which was less in CR patients than PR patients (P = 0.019). Genetic mutations at DNA damage repair genes and the JAK1 gene were also observed.

Conclusions

For advanced dMMR/MSI-H CRC, anti-PD-1 based CRIT is effective and safe. Further studies are required to better clarify the potential role and mechanism of CRIT as a viable therapeutic strategy in this population.

SUBMITTER: Zhou C

PROVIDER: S-EPMC8714781 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BackgroundPatients with colorectal carcinoma and high-grade microsatellite instability (MSI-H) or deficiency in mismatch repair (dMMR) exceptionally respond to immune checkpoint inhibitors (ICIs). ICIs are more active in treatment-naïve patients than in patients with refractory MSI-H/dMMR metastatic colorectal cancer and even more active in patients with locally advanced tumors.Material and methodsA 33-year-old male patient with Lynch syndrome was diagnosed with a locally advanced rectal cancer and refused standard neoadjuvant chemoradiation because of the potential harm of sexual dysfunction. MMR and microsatellite instability status were analyzed by immunohistochemistry and fragment length polymerase chain reaction followed by capillary electrophoresis.ResultsAfter MSI-H/dMMR was confirmed, the patient was treated with ICIs (1 mg/kg ipilimumab at day 1 and 3 mg/kg nivolumab at day 1 and 15). A complete clinical response was documented at day 21 after start of treatment. The patient underwent a total mesorectal excision at day 30. In the extirpated tissue, a complete pathological response was confirmed.ConclusionIn MSI-H/dMMR locally advanced rectal cancer short-course ICI treatment is highly effective and may be discussed in patients with dMMR locally advanced rectal cancer.Key pointsImmune checkpoint inhibitors are more active in treatment-naïve patients than in patients with refractory high-grade microsatellite instability (MSI-H)/deficiency in mismatch repair (dMMR) colorectal cancer. Standard neoadjuvant chemoradiation is less effective in MSI-H/dMMR rectal cancer patients than in patients with proficient mismatch repair. A young patient with Lynch syndrome and MSI-H/dMMR locally advanced rectal cancer refused chemoradiation in order to preserve his fertility. After neoadjuvant treatment with one dose of ipilimumab and two doses of nivolumab a complete clinical and pathological response was documented. Clinical trials are needed to first establish neoadjuvant treatment with immune checkpoint inhibitors in patients with locally advanced MSI-H/dMMR rectal cancer and thereafter to evaluate organ-preservation strategies.