Study to Evaluate the Safety and Efficacy of Filgotinib and Lanraplenib in Adults With Lupus Membranous Nephropathy (LMN)

Key Inclusion Criteria: * Kidney biopsy within the 36 months prior to screening with a histologic diagnosis of LMN (International Society of Nephrology \[ISN\] and the Renal Pathology Society \[RPS\] 2003 classification of lupus nephritis), either Class V alone, or Class V in combination with Class II. * Urine protein excretion ≥ 1.5 grams per day * Estimated glomerular filtration rate (eGFR) ≥ 40 mg/min/1.73m\^2 based on the modification of diet in renal disease (MDRD) formulation at screening * No evidence of active or latent tuberculosis (TB) as assessed during screening Key Exclusion Criteria: * Prior treatments as follows: * Previous treatment with a janus kinase (JAK) inhibitor within 3 months of Day 1 * Use of rituximab or other selective B lymphocyte depleting agents (including experimental agents) within 6 months of Day 1. Enrollment is permitted if the last dose was given \> 6 months and CD19-positive B cells are detectable at Screening. * Use of any concomitant prohibited medications as described in the protocol Note: Other protocol defined Inclusion/Exclusion criteria may apply.