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Introduction/Aims In amyotrophic lateral sclerosis (ALS) caused by superoxide dismutase 1 (SOD1) gene mutations (SOD1‐ALS), the antisense oligonucleotide tofersen had been investigated in a phase III study (VALOR) and subsequently introduced in an expanded access program. In this study we assess neurofilament light chain (NfL) before and during tofersen treatment. Methods In six SOD1‐ALS patients treated with tofersen at three specialized ALS centers in Germany, NfL in cerebrospinal fluid (CSF‐NfL) and/or serum (sNfL) were investigated using the ALS Functional Rating Scale Revised (ALSFRS‐R) and ALS progression rate (ALS‐PR), defined by monthly decline of ALSFRS‐R. Results Three of the six SOD1‐ALS patients reported a negative family history. Three patients harbored a homozygous c.272A > C, p.(Asp91Ala) mutation. These and two other patients showed slower progressing ALS (defined by ALS‐PR <0.9), whereas one patient demonstrated rapidly progressing ALS (ALS‐PR = 2.66). Mean treatment duration was 6.5 (range 5 to 8) months. In all patients, NfL decreased (mean CSF‐NfL: −66%, range −52% to −86%; mean sNfL: −62%, range −36% to −84%). sNfL after 5 months of tofersen treatment was significantly reduced compared with the nearest pretreatment measurement (P = .017). ALS‐PR decreased in two patients, whereas no changes in ALSFRS‐R were observed in four participants who had very low ALS‐PR or ALSFRS‐R values before treatment. Discussion In this case series, the significant NfL decline after tofersen treatment confirmed its value as response biomarker in an expanded clinical spectrum of SOD1‐ALS. Given the previously reported strong correlation between sNfL and ALS progression, the NfL treatment response supports the notion of tofersen having disease‐modifying activity.

Decades after its discovery in East Africa, Zika virus (ZIKV) emerged in Brazil in 2013 and infected millions of people during intense urban transmission. Whether vertebrates other than humans are involved in ZIKV transmission cycles remained unclear. Here, we investigate the role of different animals as ZIKV reservoirs by testing 1723 sera of pets, peri-domestic animals and African non-human primates (NHP) sampled during 2013–2018 in Brazil and 2006–2016 in Côte d'Ivoire. Exhaustive neutralization testing substantiated co-circulation of multiple flaviviruses and failed to confirm ZIKV infection in pets or peri-domestic animals in Côte d'Ivoire (n=259) and Brazil (n=1416). In contrast, ZIKV seroprevalence was 22.2% (2/9, 95% CI, 2.8–60.1) in West African chimpanzees (Pan troglodytes verus) and 11.1% (1/9, 95% CI, 0.3–48.3) in king colobus (Colobus polycomos). Our results indicate that while NHP may represent ZIKV reservoirs in Africa, pets or peri-domestic animals likely do not play a role in ZIKV transmission cycles.