2. REVENUES

Revenues disaggregated by category were as follows (in thousands):

 

 

The following table summarizes revenues from each of our customers who individually accounted for 10% or more of our gross revenues (as a percentage of gross revenues):

 

 

Our first and only FDA approved product, TAVALISSE®, was approved by the U.S. FDA in April 2018. We commenced commercial sale of TAVALISSE in the U.S. in May 2018. There were no product sales during the year ended December 31, 2017. Our marketing authorization application (MAA) for fostamatinib for the treatment of chronic ITP in adult patients who are refractory to other treatments was approved by the EC in January 2020 (see Note 15).

 

In addition to the distribution agreements with our customers, the SDs, we also enter into arrangements with specialty pharmacy providers, in-office dispensing providers, group purchasing organizations, and government entities that provide for government-mandated and/or privately-negotiated rebates, chargebacks and discounts with respect to the purchase of our products which reduced our gross product sales. Also refer to Revenue Recognition policy discussion in Note 1.

 

The following tables summarize activity in each of the product revenue allowances and discounts during the year ended December 31, 2019 (in thousands):

 

 

 

 

We incurred discounts and allowances for the year ended December 31, 2019 of $9.3 million, which includes the provision for current period sales of $8.1 million in the first table above, which is included as part of the Other Accrued Liabilities in the balance sheet, of which $3.3 million remained outstanding as of December 31, 2019. The remaining $1.2 million in discounts and allowances incurred related to current period sales not included in the above table for year ended December 31, 2019 relates to chargebacks, discounts and fees recorded as reductions in accounts receivable and prepaid and other current assets in the balance sheet.

 

We incurred discounts and allowances for the year ended December 31, 2018 of $3.0 million, which includes the provision for period sales of $2.7 million in the second table above, which is included as part of the Other Accrued Liabilities in the balance, of which $1.6 million remained outstanding as of December 31, 2018. The remaining $285,000 in discounts and allowances incurred related to period sales not included in the above table for year ended December 31, 2018 is recorded as reduction of accounts receivable and prepaid and other current assets in the balance sheet.

 

As of December 31, 2019, we have accounts receivable from Aclaris of $1.5 million, relative to the first amendment to the license and collaboration agreement with Aclaris. We determined that no allowance for doubtful accounts was necessary for our accounts receivable as of the years ended December 31, 2019 and 2018.