Other investment and investment receivable	9 Months Ended
Sep. 30, 2018
Investments Debt And Equity Securities [Abstract]
Other investment and investment receivable	5. Other investment and investment receivable On August 20, 2018, the Company entered into a license and collaboration agreement with Gritstone Oncology, Inc. (“Gritstone”) to utilize Gritstone’s proprietary technology platform to identify and validate tumor-specific targets and provide TCRs directed to selected targets for use in the Company’s gene therapy products. Pursuant to this agreement, the Company paid Gritstone a non-refundable, non-creditable upfront payment of $20.0 million, which is inclusive of Gritstone’s costs to perform activities allocated to it under the research plan. The Company may also make, depending upon the resulting product, future payments of up to $129.0 million per therapy product and $27.5 million per target product for development, regulatory, and commercial milestones as well as low single-digit tiered royalty payments based on annual net sales. The Company accounted for $14.5 million of the $20.0 million upfront payment as prepaid research and development costs, $3.2 million of which is reflected within prepaid expenses and $11.3 million within restricted cash and other non-current assets on the Company’s condensed consolidated balance sheet as of September 30, 2018. In future periods, the Company will recognize expense on a quarterly basis as a proportion of effort incurred by Gritstone as a percentage of total effort expected to be expended. The remaining $5.5 million of the upfront payment was expensed within research and development expense on the Company’s condensed consolidated statement of operations and comprehensive loss for the quarter ending September 30, 2018, as this payment represented an access fee for technology that has no clear alternate future use under ASC 730-10, Research and Development. The Company simultaneously entered into a stock purchase agreement with Gritstone, pursuant to which the Company purchased $10.0 million of Series C preferred shares. The Company will account for this investment as a marketable security as the Company does not have the power to control or significantly influence Gritstone’s operations. As the Series C preferred shares did not have a readily determinable fair value as of September 30, 2018, the Company elected the measurement alternative under ASC 321, Investments – Equity Securities and continued to record this investment at cost as of September 30, 2018. The investment is included within other investment and investment receivable on the Company’s condensed consolidated balance sheet as of September 30, 2018. On September 27, 2018, Gritstone announced the pricing of its initial public offering (“IPO”). In connection with Gritstone’s IPO, the Company initiated the purchase of 0.7 million common shares for $10.0 million. The purchase closed on September 28, 2018. Upon the closing of the IPO on October 2, 2018, the Company received its common shares and its Series C preferred shares were converted into common shares. As this transaction had not closed as of September 30, 2018, both the investment in Series C preferred shares of $10.0 million and the additional $10.0 million common stock investment receivable were recorded at cost within other investment and investment receivable as of September 30, 2018. In future periods, following Gritstone’s IPO, the Company will re-measure its combined $20.0 million investment in common shares at fair value at each reporting period, with subsequent changes in fair value reflected in earnings.

5. Other investment and investment receivable

On August 20, 2018, the Company entered into a license and collaboration agreement with Gritstone Oncology, Inc. (“Gritstone”) to utilize Gritstone’s proprietary technology platform to identify and validate tumor-specific targets and provide TCRs directed to selected targets for use in the Company’s gene therapy products. Pursuant to this agreement, the Company paid Gritstone a non-refundable, non-creditable upfront payment of $20.0 million, which is inclusive of Gritstone’s costs to perform activities allocated to it under the research plan. The Company may also make, depending upon the resulting product, future payments of up to $129.0 million per therapy product and $27.5 million per target product for development, regulatory, and commercial milestones as well as low single-digit tiered royalty payments based on annual net sales.

The Company accounted for $14.5 million of the $20.0 million upfront payment as prepaid research and development costs, $3.2 million of which is reflected within prepaid expenses and $11.3 million within restricted cash and other non-current assets on the Company’s condensed consolidated balance sheet as of September 30, 2018. In future periods, the Company will recognize expense on a quarterly basis as a proportion of effort incurred by Gritstone as a percentage of total effort expected to be expended. The remaining $5.5 million of the upfront payment was expensed within research and development expense on the Company’s condensed consolidated statement of operations and comprehensive loss for the quarter ending September 30, 2018, as this payment represented an access fee for technology that has no clear alternate future use under ASC 730-10, Research and Development.

The Company simultaneously entered into a stock purchase agreement with Gritstone, pursuant to which the Company purchased $10.0 million of Series C preferred shares. The Company will account for this investment as a marketable security as the Company does not have the power to control or significantly influence Gritstone’s operations. As the Series C preferred shares did not have a readily determinable fair value as of September 30, 2018, the Company elected the measurement alternative under ASC 321, Investments – Equity Securities and continued to record this investment at cost as of September 30, 2018. The investment is included within other investment and investment receivable on the Company’s condensed consolidated balance sheet as of September 30, 2018.

On September 27, 2018, Gritstone announced the pricing of its initial public offering (“IPO”). In connection with Gritstone’s IPO, the Company initiated the purchase of 0.7 million common shares for $10.0 million. The purchase closed on September 28, 2018. Upon the closing of the IPO on October 2, 2018, the Company received its common shares and its Series C preferred shares were converted into common shares. As this transaction had not closed as of September 30, 2018, both the investment in Series C preferred shares of $10.0 million and the additional $10.0 million common stock investment receivable were recorded at cost within other investment and investment receivable as of September 30, 2018. In future periods, following Gritstone’s IPO, the Company will re-measure its combined $20.0 million investment in common shares at fair value at each reporting period, with subsequent changes in fair value reflected in earnings.