Isolated neutropenia as a rare but serious adverse event secondary to immune checkpoint inhibition.

BACKGROUND: Compared to conventional chemotherapy, Immune checkpoint inhibitors (ICI) are known to have a distinct toxicity profile commonly identified as immune-related adverse events (irAEs). These irAEs that are believed to be related to immune dysregulations triggered by ICI can be serious and lead to treatment interruptions and in severe cases, precipitate permanent discontinuation. Isolated neutropenia secondary to ICI has been rarely documented in the literature and needs further description. We report a case of pembrolizumab related severe isolated neutropenia in a patient with metastatic non-small cell lung cancer. We were also able to obtain serial blood and plasma-based biomarkers for this patient during treatment and during neutropenia to understand trends that may correlate with the irAE. In addition we summarize important findings from other studies reporting on ICI related neutropenia. CASE PRESENTATION: A 74 years old Caucasian male treated with single-agent pembrolizumab for metastatic non-small cell lung cancer presented with fevers, chills, and an isolated neutrophil count (ANC) of 0 2 weeks after the fourth dose. In addition to antibiotics, due to the strong suspicion of this neutropenia being immune-mediated, he was started on 1 mg/kg of steroids and also received filgrastim to accelerate neutrophil recovery. Serial trends in C-reactive protein and certain other inflammatory cytokines demonstrated a corresponding rise at the time of neutropenia. Post recovery, his pembrolizumab was kept on hold. Eight weeks later he had a second episode of neutropenia which was again managed similar to the first episode. Despite permanent discontinuation of ICI after the first neutropenia, his disease showed an ongoing complete metabolic response on imaging. Our literature review reveals that hematological toxicities constitute < 1% irAEs with isolated neutropenia roughly accounting for one-fourth of the hematological irAEs. Based on the handful of ICI related neutropenia cases reported to date, we identified nivolumab to be the most common offender. The median number of ICI cycles administered before presenting with neutropenia was three, and the median time to recovery was approximately two weeks. All of these neutropenic episodes were ≥ grade 3 and led to permanent ICI discontinuation. Using immunosuppressive therapies in conjunction with granulocyte-colony stimulating factor was the most common strategy described to have favorable results. CONCLUSION: Neutropenia as an isolated irAE secondary to ICI is rare but represents a severe toxicity that needs early recognition and can often result in treatment discontinuations. Careful monitoring of these patients with the prompt initiation of immunosuppressive and supportive measures to promote rapid recovery as well as prevent and treat infectious complications should be part of the management algorithms. Serial monitoring of blood and plasma-based biomarkers from more extensive studies may help in identifying patients at risk for irAEs and thus guide patient selection for ICI.

A rapidly growing human papillomavirus-positive oral tongue squamous cell carcinoma in a 21-year old female: A case report.

Oral tongue squamous cell carcinoma (OTSCC) has a median age at diagnosis of 62 years. The incidence of OTSCC in young adults has been increasing, and the reason is unclear. The present study describes a case, and molecular analysis, of OTSCC in a 21-year-old female. Clinical and pathological information were collected from medical records. Formalin-fixed paraffin-embedded biopsy tissue from the patient was reassessed using standard hematoxylin & eosin staining, and immunohistochemistry was used to assess the expression of cellular p16, MutL homolog (MLH)1, MLH2, MutS homolog 6 (MSH6) and PMS1 homolog 2 (PMS2). The human papilloma virus (HPV) genome was detected by PCR analysis of the extracted DNA. The young age of the patient with OTSCC was unusual. The original pathology report indicated koilocytotic atypia, a cellular abnormality associated with HPV. Although HPV-positive oral cancer tends to occur in 'younger' individuals, 21 years is unusual. The confirmation of biologically active HPV in the tumor was obtained via the observation of strong positive staining for cellular p16. The patient described a maternal family cluster of rare cancer types, thus the possibility that this rapidly growing cancer resulted from HPV infection combined with an underlying genetic mutation causing decreased DNA-mismatch repair was explored. However, MSH1, MSH2, MSH6 and PSM2, proteins that are associated with Lynch Syndrome, were expressed at normal levels. A rapidly growing OTSCC of a 21-year-old female was determined to be HPV-positive. The patient underwent combination chemotherapy and radiation and has experienced long-term survival without recurrence. The reason this tumor grew so quickly in such a young individual remains unknown. These types of cases warrant additional genomic and proteomic studies to improve understanding of this phenomenon.