During the three months ended June 30, 2021 and 2020, net product sales in the United States were $49.1 million and $36.2 million, respectively, consisting solely of Emflaza, and net product sales not in the United States were $54.0 million and $39.0 million, respectively, consisting of Translarna, Tegsedi, and Waylivra. For the three months ended June 30, 2021 and 2020, the Company had a total of 2 and 2 distributors, respectively, that each accounted for over 10% of the Company’s net product sales.
During the six months ended June 30, 2021 and 2020, net product sales in the United States were $92.7 million and $63.6 million, respectively, consisting solely of Emflaza, and net product sales not in the United States were $101.7 million and $79.8 million, respectively, consisting of Translarna, Tegsedi, and Waylivra. For the six months ended June 30, 2021 and 2020, the Company had a total of 2 and 3 distributors, respectively, that each accounted for over 10% of the Company's net product sales.
As of June 30, 2021, the Company does not have a contract liabilities balance. As of December 31, 2020, the Company’s contract liabilities balance was $4.2 million. The Company did not have any contract assets as of June 30, 2021 and as of December 31, 2020. During the three and six month periods ended June 30, 2021, the Company recognized $1.9 million and $4.0 million of revenue, respectively, related to the amounts included in the contract liability balance at the beginning of the period. During the three and six month periods ended June 30, 2020, the Company recognized $2.0 million and $4.0 million of revenue, respectively, related to the amounts included in the contract liability balance at the beginning of the period. The Company has not made significant changes to the judgments made in applying ASC Topic 606 for the three and six month periods ending June 30, 2021 and 2020.
Remaining performance obligations
Remaining performance obligations represent the transaction price for goods the Company has yet to provide. As of June 30, 2021 the Company does not have any remaining performance obligations relating to Translarna net product revenue. As of December 31, 2020, the aggregate amount of the transaction price allocated to the remaining performance obligations relating to Translarna net product revenue was $4.2 million.
Collaboration and Royalty revenue
In November 2011, the Company and the SMA Foundation entered into the SMA License Agreement with Roche. Under the terms of the SMA License Agreement, Roche acquired an exclusive worldwide license to the Company’s SMA program.
The Company is eligible to receive additional payments from Roche if specified events are achieved with respect to each licensed product, including up to $135.0 million in research and development event milestones, up to $325.0 million in sales milestones upon achievement of specified sales events, and up to double digit royalties on worldwide annual net sales of a commercial product.
The SMA program currently has one approved product, Evrysdi™ (risdiplam), which was approved in August 2020 by the FDA for the treatment of SMA in adults and children two months and older. As of June 30, 2021, the remaining potential research and development event milestones that can be received is $10.0 million, which will be achieved upon the first commercial sale in Japan, and the remaining potential sales milestones that can be received is $325.0 million.
For the three months ended June 30, 2021 and 2020, the Company did 0t recognize collaboration revenue related to the SMA License Agreement. For the six months ended June 30, 2021 and 2020, the Company recognized collaboration revenue related to the SMA License Agreement of $20.0 million and $0.1 million, respectively. The first commercial sale of Evrysdi in the European Union was made in March 2021. This event triggered a $20.0 million milestone payment to the Company from Roche, which was recognized in the six months ended June 30, 2021. NaN milestones were triggered in the six months ended June 30, 2020.
In addition to research and development and sales milestones, the Company is eligible to receive up to double-digit royalties on worldwide annual net sales of a commercial product under the SMA License Agreement. For the three and six months ended June 30, 2021, the Company has recognized $13.6 million and $20.2 million of royalty revenue related