Whole exome sequencing uncovers HRAS mutations as potential mediators of resistance to metronomic chemotherapy

OBJECTIVES

The aim of this pilot study is to identify the genetic factors that contribute to the response of metronomic chemotherapy in head and neck squamous cell carcinoma (HNSCC) patients using whole-exome sequencing (WES). This study would facilitate the identification of predictive biomarkers, which would enable personalized treatment strategies and improve treatment outcomes for patients with HNSCC.

MATERIALS AND METHODS

We have selected patients with recurrent head and neck cancer who underwent metronomic chemotherapy. Sequential tumor biopsies were collected from the patients at different stages of treatment to capture the genomic alterations and tumor evolution during metronomic chemotherapy and sequenced using WES.

RESULTS

We identified several known HNSCC hallmark genes reported in COSMIC, including KMT2B, NOTCH1, FAT1, TP53, HRAS, CASP8, and CDKN2A. Copy number alteration analysis revealed amplifications and deletions in several oncogenic and tumor suppressor genes. COSMIC Mutational Signature 15 associated with defective DNA mismatch repair was enriched in 73% of HNSCC samples. Further, the comparison of genomic alterations between responders and non-responders identified HRAS gene uniquely mutated in non-responders that could potentially contribute to resistance against metronomic chemotherapy.

DISCUSSION

Our findings corroborate the molecular heterogeneity of recurrent HNSCC tumors and establish an association between HRAS mutations and resistance to metronomic chemotherapy, suggesting HRAS as a potential therapeutic target. Combining HRAS inhibitors with metronomic regimens could improve treatment sensitivity in HRAS-mutated HNSCC patients. Further studies are needed to fully elucidate the genomic mechanisms underlying the response to metronomic chemotherapy.

Complete and enduring response in an elderly patient with repeated recurrent gingival squamous cell carcinoma treated by combined toripalimab and single agent chemotherapy: a case report

Combined immune checkpoint inhibitor with platinum-based doublet chemotherapy brought about significant improvement in overall survival as the first line treatment in metastatic and recurrent head and neck cancer patients. However, in elderly patients with relatively poor performance status, these regimens might not be well tolerated. Therefore, we evaluated the safety and effect of combined immunotherapy and single agent chemotherapy in an elderly patient with recurrent head and neck squamous cell carcinoma. A 78-year-old male patients with a repeatedly recurrent gingival squamous cell carcinoma was admitted in our institute. Previously this patient underwent two consecutive surgical resections of recurrent tumors before the second rapid recurrence that resulted in extended tumor mass and lymph node metastasis. As the patient was in a relatively poor performance status (performance status =2), immunotherapy with PD-1 antibody (Toripalimab) combined with single agent chemotherapy (two cycle with albumin-bound paclitaxel and then six cycles with gemcitabine) was administrated, which led to clinical complete response after 8 cycles of treatment. The patient continued 4 cycles of maintenance immunotherapy with Toripalimab until the outbreak of the coronavirus disease 2019. The treatment was well tolerated and the patient remained free from disease until the last follow up by June 2020, 16 months after the initiation of treatment. The success in this case indicated that the combination of anti-PD-1 antibody and single chemotherapy agent may also be effective as well as safe in elderly patients with recurrent head and neck squamous cell carcinoma.