Combining Panitumumab With Anti-PD-1 Antibody in Cutaneous Squamous Cell Carcinoma of the Head and Neck After Inadequate Response to Anti-PD-1 Antibody Alone.

Anti-epidermal growth factor receptor (EGFR) antibodies and anti-programmed cell death 1 protein (PD-1) antibodies have been used separately to treat metastatic cutaneous squamous cell carcinoma (cSCC). While two anti-EGFR antibodies have similar clinical activity, cetuximab is administered weekly, whereas panitumumab is administered every two weeks. This report details findings using panitumumab in combination with anti-PD-1 antibody in patients with relapsed refractory cSCC. Three consecutive patients with poor performance status and rapidly progressive recurrent cutaneous squamous cell carcinoma (cSCC) of the face or scalp signed informed consent to receive an anti-PD-1 antibody with the option to add panitumumab were there inadequate response. After 2, 5, and 7 cycles of anti-PD-1 antibody treatment, respectively, panitumumab was added and the combination was continued for 27, 7, and 5 cycles, respectively. Fatigue, rash, and hypomagnesemia were reported, consistent with expectations for either agent alone. All three patients achieved durable complete response. The favorable clinical outcomes support further evaluation of the combination of anti-PD1 and anti-EGFR antibodies to control refractory cSCC of the face or scalp. J Drugs Dermatol. 2021;20(8):901-904. doi:10.36849/JDD.6175.

CD49f protein expression varies among genetic subgroups of B lymphoblastic leukemia and is distinctly low in KMT2A-rearranged cases.

BACKGROUND: CD49f (integrin α6) is a useful marker for minimal residual disease (MRD) detection in B lymphoblastic leukemia and has recently been suggested to mediate infiltration of the central nervous system by leukemic B lymphoblasts. However, data regarding expression of CD49f protein in B lymphoblastic leukemia are limited, and whether CD49f protein expression varies among genetic subgroups of B lymphoblastic leukemia is unknown. METHODS: CD49f protein expression was characterized by flow cytometry in a series of 40 cases of B lymphoblastic leukemia, which included the genetic subgroups: KMT2A-rerranged, BCR-ABL1+, ETV6-RUNX1+, hypodiploidy, and hyperdiploidy. RESULTS: Expression of CD49f differed significantly among the five genetic subgroups studied, whether assessed by percentage of blasts positive for the antigen (p = .0001, Kruskal-Wallis) or median fluorescence intensity (MFI) (p = .0001, Kruskal-Wallis). Moreover, the percentage of CD49f+ blasts and MFI of CD49f were significantly lower in KMT2A-rearranged cases than in cases without KMT2A rearrangement (p = .0002 for both, Mann-Whitney). CONCLUSIONS: CD49f protein expression varies among genetic subgroups of B lymphoblastic leukemia, and is distinctly low in KMT2A-rearranged cases.