Summary An intronic GGGGCC repeat expansion in C9ORF72 is the most common cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), but its pathogenic mechanism remains unclear. Here we use human induced motor neurons (iMNs) to show that repeat-expanded C9ORF72 is haploinsufficient in ALS. We show that C9ORF72 interacts with endosomes and is required for normal vesicle trafficking and lysosomal biogenesis in motor neurons. Repeat expansion reduces C9ORF72 expression, triggering neurodegeneration through two mechanisms: accumulation of glutamate receptors leading to excitotoxicity, and impaired clearance of neurotoxic dipeptide repeat proteins derived from the repeat expansion. Thus, cooperativity between gain- and loss-of-function mechanisms leads to neurodegeneration. Restoring C9ORF72 levels or augmenting its function with constitutively active RAB5 or chemical modulators of RAB5 effectors rescues patient neuron survival and ameliorates neurodegenerative processes in both gain- and loss-of function C9ORF72 mouse models. Thus, modulating vesicle trafficking can rescue neurodegeneration caused by the C9ORF72 repeat expansion. Coupled with rare mutations in ALS2, FIG4, CHMP2B, OPTN, and SQSTM1, our results reveal mechanistic convergence on vesicle trafficking in ALS/FTD.

Background: Patients with malignancy are particularly vulnerable to infection with Severe Acute Respiratory Disease-Coronavirus-2 (SARS-CoV-2) given their immunodeficiency secondary to their underlying disease and cancer-directed therapy. We report a case series of patients with cancer who received convalescent plasma, an investigational therapy for severe Coronavirus Disease 2019 (COVID-19). Methods: Patients with cancer were identified who received convalescent plasma. Enrolled patients had confirmed COVID-19 with severe or life-threatening disease and were transfused with convalescent plasma from donors with a SARS-CoV-2 anti-spike antibody titer of ≥ 1:320 dilution. Oxygen requirements and clinical outcomes of interests were captured as well as laboratory parameters at baseline and 3 days after treatment. Results: We identified 24 patients with cancer, 14 of whom had a hematological malignancy, who were treated with convalescent plasma. Fifteen patients (62.5%) were on cancer-directed treatment at the time of COVID-19 infection. After a median of hospital duration of 9 days, 13 patients (54.2%) had been discharged home, 1 patient (4.2%) was still hospitalized, and 10 patients had died (41.7%). Non-intubated patients, particularly those on nasal cannula alone, had favorable outcomes. Three mild febrile non-hemolytic transfusion reactions were observed. C-reactive protein significantly decreased after 3 days of treatment, while other laboratory parameters including ferritin and D-dimer remained unchanged. Conclusions: Convalescent plasma may be a promising therapy in cancer patients with COVID-19.

The host response to SARS-CoV-2, the etiologic agent of the COVID-19 pandemic, demonstrates significant inter-individual variability. In addition to showing more disease in males, the elderly, and individuals with underlying comorbidities, SARS-CoV-2 can seemingly render healthy individuals with profound clinical complications. We hypothesize that, in addition to viral load and host antibody repertoire, host genetic variants impact vulnerability to infection. Here we apply human induced pluripotent stem cell (hiPSC)-based models and CRISPR-engineering to explore the host genetics of SARS-CoV-2. We demonstrate that a single nucleotide polymorphism (rs4702), common in the population, and located in the 3’UTR of the protease FURIN, impacts alveolar and neuron infection by SARS-CoV-2 in vitro. Thus, we provide a proof-of-principle finding that common genetic variation can impact viral infection, and thus contribute to clinical heterogeneity in COVID-19. Ongoing genetic studies will help to identify high-risk individuals, predict clinical complications, and facilitate the discovery of drugs.

Conflict of interest: JKI is a cofounder of AcuraStem Incorporated. JKI declares that he is bound by confidentiality agreements that prevent him from disclosing details of his financial interests in this work. BVZ is a scientific founder and chairs the scientific advisory board of ZZ Biotech LLC, a biotechnology company with a mission to develop activated protein C and its functional mutants for the treatment of stroke and other neurological disorders.