def filter_by_pert_agent(target_pert_agent, gse_gsm_info):
    """
    Filter GSE by perturbation agent
    Args:
        target_pert_agent: the perturbation agent to be filtered
        gse_gsm_info: the GSE and GSM info tuple

    Returns:
        filtered results
    """
    gse_id, gsm_info = gse_gsm_info
    pert_agent = gsm_info[6].lower()
    target_pert_agent = target_pert_agent.lower()

    return pert_agent in target_pert_agent or target_pert_agent in pert_agent