amendment, Servier has exercised its option to acquire the exclusive worldwide rights to further develop and commercialize UCART19. In addition, in November 2015, Pfizer and Servier entered into an exclusive global license and collaboration agreement under which Pfizer obtained from Servier exclusive rights to develop and commercialize UCART19 in the United States. We entered into amendments to our collaboration agreements with each of Servier and Pfizer to facilitate this agreement between Servier and Pfizer. In connection with the entry into these amendments, Servier made an upfront payment of $38.5 million, excluding taxes. As of December 31, 2017, Cellectis was eligible to receive up to $1,064 million in potential option exercise fees, development, clinical and sales milestones, in addition to royalties on sales and research and development costs reimbursements. In connection with the Asset Contribution Agreement described above, Allogene has received Pfizer’s rights to UCART19, which were licensed to Pfizer by Servier.
We believe that our strategic collaborations with Allogene and Servier position us to compete in the promising field of immuno-oncology and add additional clinical and financial resources to our programs.
In 2015, we have also entered into research and development alliances with each of Cornell University and the MD Anderson Cancer Center. Pursuant to these strategic alliances, we collaborate with these two centers to accelerate the development of our lead product candidates UCART123, UCARTCS1, and UCART22. These agreements provide that Cellectis funds the research and development activities performed at Cornell University and the MD Anderson Cancer Center. Our research and development alliance with Cornell University ended in June 2018. Although our research and development alliance with Cornell University has terminated, our clinical trial agreement for the UCART123 clinical study for AML remains in effect.
Our cash consumption is driven by our internal operational activities, as well as our outsourced activities, including the preclinical activities and the manufacturing activities of the requisite raw materials for the manufacturing of UCART123, UCART22 and UCARTCS1, the technology transfer of UCART22 and UCARTCS1 process to CELLforCURE, and the GMP manufacturing of UCART123, UCART22 and UCARTCS1 at CELLforCURE and MolMed S.p.A. In addition, we incur significant annual payment and royalty expenses related to ourin-licensing agreements with different parties including l’Institut Pasteur, Life Technologies Corporation and The Regents of the University of Minnesota. In addition, in 2017, we initiated our clinical studies at Joan and Sanford I. Weill Medical College and The New York Presbyterian Hospital (collectively referred to as Weill Cornell) and the University of Texas MD Anderson Cancer Center (the MD Anderson Cancer Center) leading to additional cash burn through payments to the clinical research centers, the Contract Research Organization involved in the studies Medpace and the companies engaged to provide logistics and testing of clinical sample material for the studies. We are also engaged in new agreements foron-going or future clinical trials, such as clinical trial agreements with new sites, or services agreement with Contract Research Organization.
In addition to our cash generated by operations (including payments under our strategic alliances), we have funded our operations primarily through private and public offerings of our equity securities, grant revenues, payments received under intellectual property licenses, and reimbursements of research tax credits. Our ordinary shares have traded on the Euronext Growth market of Euronext in Paris since February 7, 2007. In March 2015, we completed our U.S. initial public offering of 5,500,000 American Depositary Shares (“ADS”) on the Nasdaq Global Market for gross proceeds of $228.2 million. On July 25, 2017, Calyxt completed its Nasdaq IPO, selling an aggregate of 8,050,000 shares of common stock for gross proceeds of approximately $64.4 million, inclusive of $20.0 million from Cellectis’ purchase of shares in the IPO. In April, 2018, Cellectis closed afollow-on offering of 5,646,000 ADS at a public offering price of $31.00 per ADS resulting in gross proceeds of $175 million. In May, 2018, Calyxt closed afollow-on offering of 4,057,500 ADS at a public offering price of $15.00 per ADS resulting in gross proceeds of $60.9 million. Cellectis purchased 550,000 shares of common stock at the public offering price of $15.00. In addition, in connection with the vesting on June 14, 2018, of restricted stock units for certain employees and nonemployees of Calyxt and Cellectis, Cellectis purchased approximately 63,175 shares of common stock of Calyxt at a price of $19.49 per share (the closing price reported on the Nasdaq Global Market on June 14, 2018) directly from such employees and nonemployees in private transactions pursuant to share purchase agreements dated June 13, 2018.
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