immune checkpoint inhibitors

Byaibio

Immune checkpoint inhibitors (pd 1 and ctla 4-targeting ICIs) are a cancer immunotherapy class that releases inhibitory brakes on antitumor T-cell activity, producing durable responses in selected tumors and, in some settings, long-term survival or even cure. They are used across many malignancies, including mismatch repair deficient, dmmr msi h, microsatellite instability high metastatic colorectal cancer, urothelial carcinoma, hepatocellular carcinoma, cervical cancer, esophageal squamous cell carcinoma, bladder cancer, renal cell carcinoma, and non small cell lung cancer, but benefit is highly variable and a considerable subset of patients with mismatch repair-deficient endometrial cancer does not achieve meaningful clinical benefit. Recent literature emphasizes biomarker-guided use, including transcriptomic resistance signatures, programmed death ligand 1, tumor mutation burden, tertiary lymphoid structures, baseline D-dimer, and gut microbiome features, with some studies highlighting low-dose receptor occupancy and sequencing with chemotherapy or radiotherapy. In gastrointestinal and colorectal cancers, efficacy remains limited in most microsatellite-stable disease and in settings with dense extracellular matrix or hypoalbuminemia, although microbiota modulation, fecal microbiota transplantation, and arginine supplementation have been explored to improve response. In brain tumors and pediatric solid tumors, ICIs are promising but constrained by the BBB, immune suppression, heterogeneity, and strong monotherapy resistance, while combination strategies are being tested to overcome these barriers. Toxicity is a major issue, with immune-related adverse events including colitis, hepatotoxicity, autoimmune hemolytic anemia, and acute interstitial nephritis, prompting guideline-based toxicity management.

Mismatch repair-deficient and MSI-H tumors

Gastrointestinal and hepatobiliary cancers

  • In colorectal cancer, ICIs remain limited in most microsatellite-stable disease, with gut microbiota modulation proposed as a way to enhance efficacy. (PMID:41981741)
  • A phase I study of fecal microbiota transplantation plus anti-PD-1 therapy in refractory microsatellite-stable gastric cancer reported feasibility and safety. (PMID:41871875)
  • ICIs were evaluated in advanced hepatocellular carcinoma and described as standard therapy in that setting, with randomized and real-world data supporting long-term survival and a cure fraction in some patients. (PMID:42007976; PMID:42008357)
  • In gastric cancer and advanced esophageal cancer, sequencing of immunochemotherapy was assessed for survival impact. (PMID:41941004)

Thoracic, genitourinary, and gynecologic cancers

  • ICIs improved clinical outcomes in non small cell lung cancer, and ultra-low-dose therapy achieved sufficient receptor occupancy at doses below standard approved levels. (PMID:41867453; PMID:41604598)
  • In urothelial carcinoma and bladder cancer, ICIs were described as revolutionizing treatment and expanding neoadjuvant/systemic options. (PMID:41560593; PMID:41774881)
  • ICIs were approved for cervical cancer and associated with survival benefit in locally advanced and recurrent/metastatic disease. (PMID:41958269)
  • In renal cell carcinoma, biomarker work suggested STING promoter methylation may help predict response. (PMID:41942521)

Melanoma, brain tumors, and pediatric solid tumors

  • In metastatic melanoma, transcriptomic signatures including cxcl13, fdcsp, grik3, igkc, mzb1, and wdr63 were linked to primary resistance to ICIs. (PMID:41913413)
  • ICIs showed suboptimal responses in mucosal melanoma, underscoring a resistant melanoma subtype. (PMID:41944928)
  • For glioblastoma multiforme, ICIs were considered promising but limited by BBB penetration, immune suppression, and tumor heterogeneity. (PMID:41720042)
  • In pediatric solid tumors, ICIs were largely ineffective as monotherapy in unselected populations but could produce durable responses in molecularly defined subsets. (PMID:41984108)

Biomarkers, combinations, and resistance

  • tertiary lymphoid structures were repeatedly highlighted as predictors of ICI response, including in breast cancer and Merkel cell carcinoma. (PMID:42028730; PMID:41466351)
  • gut microbiota composition and gene-level microbiome signatures were reported as important determinants of ICI response across cancer types. (PMID:42026803; PMID:41560593)
  • hypoalbuminemia was shown to drive resistance, while arginine supplementation restored efficacy in the reported model. (PMID:41940988)
  • ICIs were combined with radiation therapy in clinical trials, but the expected synergy from preclinical models was not reproduced. (PMID:41984232)

Toxicity and immune-related adverse events

  • ICIs were associated with immune-related adverse events, including colitis and severe toxicities in advanced cancer treatment. (PMID:41992000; PMID:41973154)
  • Multicenter data linked ICIs to immune-mediated liver injury and hepatotoxicity. (PMID:41972337)
  • Case reports described immunotherapy-associated autoimmune hemolytic anemia after PD-1 ICI use. (PMID:41944848)
  • Immune checkpoint-related nephritis, including acute interstitial nephritis, was also reported as a clinically important irAE. (PMID:41785046)