Immune Checkpoint Inhibition as Primary Adjuvant Therapy for an IDH1-Mutant Anaplastic Astrocytoma in a Patient with CMMRD: A Case Report-Usage of Immune Checkpoint Inhibition in CMMRD

Curr Oncol. 2021 Feb 1;28(1):757-766. doi: 10.3390/curroncol28010074.


Constitutional mismatch repair deficiency (CMMRD) is a rare autosomal recessive hereditary cancer syndrome due to biallelic germline mutation involving one of the four DNA mismatch repair genes. Here we present a case of a young female with CMMRD, homozygous for the c.2002A>G mutation in the PMS2 gene. She developed an early stage adenocarcinoma of the colon at the age of 14. Surveillance MRI of the brain at age 18 resulted in the detection of an asymptomatic brain cancer. On resection, this was diagnosed as an anaplastic astrocytoma. Due to emerging literature suggesting benefit of immunotherapy in this patient population, she was treated with adjuvant dual immune checkpoint inhibition, avoiding radiation. The patient remains stable with no evidence of progression 20 months after resection. The patient's clinical course, as well as the rational for considering adjuvant immunotherapy in patients with CMMRD are discussed in this report.

Trial registration: NCT02992964.

Keywords: CMMRD; adjuvant therapy; checkpoint inhibitors; constitutional mismatch repair deficiency; immunotherapy; screening; surveillance; tumor mutational burden.

Publication types

  • Case Reports

MeSH terms

  • Adolescent
  • Astrocytoma* / drug therapy
  • Astrocytoma* / genetics
  • Brain Neoplasms* / drug therapy
  • Brain Neoplasms* / genetics
  • Colorectal Neoplasms
  • Female
  • Humans
  • Immune Checkpoint Inhibitors
  • Isocitrate Dehydrogenase / genetics
  • Neoplastic Syndromes, Hereditary*


  • Immune Checkpoint Inhibitors
  • Isocitrate Dehydrogenase
  • IDH1 protein, human

Supplementary concepts

  • Turcot syndrome

Associated data