ContractStartDate & ContractEndDate returning dummy dates (1900-01-01 & 4000-01-01) - how can I remove them?

ContractStartDate & ContractEndDate returning dummy dates (1900-01-01 & 4000-01-01) - how can I remove them? I'll be using DirectQuery in Power BI to build a report but been asked to remove the "Dummy Dates". Any suggestions would be appreciated.

Select * from(

SELECT [ContactID]
      ,a.[InjixoID]
      ,a.[start_date] as ContractStartDate
      ,a.[end_date] as ContractEndDate
	  ,b.EmployeeID
	  ,b.[Full name]
	  ,c.LeaveDate as CiphrLeaveDate
	  ,d.ContractName
	  ,d.ContractHours
	  ,d.NoOfDays
	  ,(ROW_NUMBER() over (partition by a.InjixoID Order by a.[start_date] desc)) as rn
  FROM [Staging].[InjixoContactsbyPU] a

  left join InjixoUsers b on a.InjixoID = b.InjixoID
  left join Employees c on b.EmployeeID = c.EmployeeId
  left join InjixoContracts d on a.ContactID = d.contract_id
  left join InjixoEmployeePeriods e on b.InjixoID = e.employee_id

  where a.end_date >= getdate() 
  --order by b.EmployeeID
  ) t1

  where t1.rn = 1