Client code using Exponential Backoff

        public async Task<Catalog> GetCatalogItems(int page,int take, int? brand, int? type)
        {
            _apiClient = new HttpClient();
            var itemsQs = $"items?pageIndex={page}&pageSize={take}";
            var filterQs = "";

            if (brand.HasValue || type.HasValue)
            {
                var brandQs = (brand.HasValue) ? brand.Value.ToString() : "null";
                var typeQs = (type.HasValue) ? type.Value.ToString() : "null";
                filterQs = $"/type/{typeQs}/brand/{brandQs}";
            }

            var catalogUrl = $"{_remoteServiceBaseUrl}items{filterQs}?pageIndex={page}&pageSize={take}";
            var dataString = "";

            //
            // Using HttpClient with Retry and Exponential Backoff
            //
            var retry = new RetryWithExponentialBackoff();
            await retry.RunAsync(async () =>
            {
                // work with HttpClient call
                dataString = await _apiClient.GetStringAsync(catalogUrl);
            });

            //var dataString = await _apiClient.GetStringAsync(catalogUrl);
            var response = JsonConvert.DeserializeObject<Catalog>(dataString);

            return response;
        }

Can this code be implemented for synchronous method?