​

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

​

​

The following table summarizes the percentages of revenues from each of our customers who individually accounted for 10% or more (wherein * denotes less than 10%) of the total net product sales and revenues from collaborations:

​

​

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. Fostamatinib is marketed in Europe under the brand name TAVLESSE™ (fostamatinib). Grifols launched TAVLESSE in the UK and Germany in July 2020, and thereafter expects a phased roll-out-out over the next 18 months across Europe. In December 2020, the Scottish Medicines Consortium accepted TAVLESSE for use in NHS in Scotland.

​

In addition to the distribution agreements with our customers and 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 3” above.

​

The following table summarizes activity in each of the product revenue allowance and reserve categories for the three months ended March 31, 2021 and 2020 (in thousands):

​

​

​

​

Of the $3.7 million discounts and allowances from gross product sales for the three months ended March 31, 2021, $3.3 million was accounted for as additions to other accrued liabilities and $434,000 as reductions in accounts receivable and prepaid and other current assets in the balance sheet. Other accrued liabilities related to the discounts and allowances had a remaining outstanding balance of $5.4 million as of March 31, 2021.

​

Of the $2.7 million discounts and allowances from gross product sales for the three months ended March 31, 2020, $2.2 million was accounted for as additions to other accrued liabilities and $467,000 as reductions in accounts receivable and prepaid and other current assets in the balance sheet. Other accrued liabilities related to the discounts and allowances had a remaining outstanding balance of $3.5 million as of March 31, 2020.