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Globally, the efforts to find the best cancer treatment are demanding and very intensive. Immunotherapy has gained an important role as a second or sometimes first line of treatment for various types of cancer. PD-1/PD-L1 checkpoint inhibitors are an impending category of immunotherapy, and their mechanism, as well as their interaction with T cells, are well studied. However, our knowledge about any possible effect(s) of immunotherapy on B cells is limited. In this prospective study, we asked the question of any possible alterations of circulating B cells (numbers and subsets) occurring during immunotherapy in patients with cancer and of the potential correlation of such changes with the outcomes and with development of immune-related adverse events (irAEs). We enrolled 20 cancer patients who received PD-1 checkpoint inhibitors and 8 healthy donors (HD). Patients underwent regular clinical assessment and imaging using the iRECIST criteria for 6 months following immunotherapy. Peripheral blood samples were collected before and during PD-1 checkpoint inhibitor therapy, and flow cytometry analysis of peripheral blood mononuclear cells (PBMCs) was performed, evaluating various circulating B cell subset phenotypes, including mature naïve B cells, memory B cells, regulatory B cells (Bregs), antibody-secreting cells (ASCs), and age-related B cells (ABCs). Statistical analysis was employed to compare the differences of B cells between different groups and among sequential data within the same group. Total circulating CD19+ B cell counts remained stable across both groups (responders (R), nonresponders (NR)) and timepoints. However, there was a significant rise in mature naïve B cells and decline in memory B cells at the initiation of the treatment in the R group compared to healthy donors and to the NR group. Such changes were correlated with a good response to immunotherapy. On the contrary, higher numbers of ABCs at baseline were seen in the NR group and were correlated with resistance to treatment. As far as immune-related adverse events are concerned, no significant changes were recorded among the different B cell subpopulations evaluated in both groups. Our study provides preliminary data suggesting that B cell subset changes during immunotherapy may correlate with immune checkpoint inhibitor-induced clinical responses in patients with neoplasia. Further investigations to delineate the potential role(s) of B cells in patients undergoing immunotherapy are needed.

Abstract Immune checkpoint inhibitors are a promising new therapeutic strategy in oncology that aims to eliminate cancer cells by enhancing patients' immune response against tumor antigens. Despite their beneficial effects, immune checkpoint inhibitors are also responsible for a plethora of autoimmune manifestations, known as immune-related adverse events. We present a case of eosinophilic fasciitis-like disorder in an 81-year-old patient treated with the programmed death cell protein 1 inhibitor pembrolizumab for non-small-cell lung cancer. The patient developed characteristic indurated skin lesions in his limbs after 1½ years of treatment with pembrolizumab and a typical “groove sign.” Raynaud’s syndrome was absent. A full-thickness biopsy confirmed the clinical diagnosis of an “EF-like” condition. Neither peripheral eosinophilia nor eosinophilic infiltrates in the skin biopsy were found. His symptoms improved after a 2.5-month CPI discontinuation and treatment with 16 mg of methylprednisolone slowly tapered to a dose of 4 mg. Eosinophilic fasciitis is a rare immune-related adverse event of CPI treatment; our literature search identified only 12 cases that fulfill the criteria of EF in patients receiving CPIs.

Isolated neutropenia without anemia or thrombocytopenia is a common clinical problem. The etiology of neutropenia may vary from transient bone marrow suppression, caused by self-limited viral illnesses, to previously undiagnosed congenital syndromes or serious systemic diseases. Consequently, determining the underlying cause of neutropenia and what treatment is required can be challenging. Acquired neutropenia is common and most of the times an etiologic factor can be found. Congenital neutropenia (CN) is rare, and we still have a lot to learn from mutational analysis as to the exact role of gene abnormalities in the pathogenesis of these complex diseases. This mini-review discusses a proposed approach to neutropenia in the adult patient.