circumstances and annual minimum royalties that increase over time. In addition, we must pay NCH a portion of sublicensing revenue received from our sublicense of the licensed technology at percentages between low-double digits and low-teens.
On November 6, 2015, the FDA approved our sponsorship of the IND and the transfer of the associated regulatory filing from NCH.
ReGenX Biosciences, LLC
In March 2014, we entered into an exclusive license agreement with ReGenX Biosciences, LLC, or ReGenX Biosciences, predecessor to REGENXBIO Inc., or REGENX, under certain patent rights owned by the Trustees of the University of Pennsylvania and licensed to ReGenX Biosciences, for the development and commercialization of products to treat spinal muscular atrophy by in vivo gene therapy using AAV9, or the ReGenX SMA License. Under the ReGenX SMA License, we paid ReGenX Biosciences an initial licensing fee of $2.0 million. We are also required to pay ReGenX Biosciences: annual maintenance fees, up to $12.25 million in milestone fees for all products covered by the ReGenX SMA License, or ReGenX SMA licensed products; mid-single to low-double digit royalty percentages on net sales of ReGenX SMA licensed products, subject to reduction in specified circumstances; and lower mid-double digit percentages of any sublicense fees we receive from sublicensees for the licensed patent rights. As of September 30, 2017, we have paid $2.4 million under the ReGenX SMA License, which includes $0.3 million in aggregate milestone payments.
Asklepios Biopharmaceutical, Inc.
In May 2015, we entered into a non-exclusive, worldwide license agreement with Asklepios Biopharmaceutical, Inc., or AskBio, under certain patents and patent applications, for the use of AskBio’s self-complementary AAV genome technology for the treatment of SMA in humans, or the AskBio License. Under the AskBio License, we paid AskBio a one-time upfront license fee of $1.0 million, payable across stipulated milestones. We are also required to pay ongoing annual maintenance fees, up to a total of $0.6 million in clinical development milestone payments and up to a total of $9.0 million in commercial milestone payments. Under the terms of the AskBio License, we are required to pay AskBio annual tiered royalties on net sales of any products covered by the AskBio License, on a country-by-country basis, starting at percentages in the low-single digits and increasing to mid-single digits. These royalty rates are subject to potential reduction in specified circumstances, including, in the event we exercise our option to make a specified one-time royalty option fee payment to AskBio. We must also pay AskBio a low-double digit percentage of all consideration we receive from any sublicense of the licensed technology. Through September 30, 2017, we have paid the $1.0 million upfront license fee owed under the AskBio License.
Preclinical Programs for Rett Syndrome and ALS
We have also entered into three license agreements relating to our planned new programs for Rett syndrome and ALS.
Effective June 7, 2017, we entered into an exclusive license agreement with REGENX under certain patents and patent applications owned by the Trustees of the University of Pennsylvania and licensed to REGENX, for the development and commercialization of products to treat Rett syndrome and genetic ALS using the AAV 9 vector, or the REGENX Rett and ALS License. Under the REGENX Rett and ALS License, REGENX granted us an exclusive, worldwide license under the licensed patent rights to make, have made, use, import, sell and offer for sale any products covered by the REGENX Rett and ALS License, or the REGENX Rett and ALS licensed products, in the field of the treatment of (i) Rett syndrome in humans by in vivo gene therapy using AAV9 delivering the gene encoding for methyl CpG binding protein 2, and (ii) ALS caused by SOD1 mutation in humans by in vivo gene therapy using AAV9 delivering the gene encoding for SOD1, subject to certain rights reserved by REGENX and its licensors. The patent rights exclusively in-licensed include an issued United States patent, which expires in 2026. We have the right to sublicense the licensed technology to third parties subject to certain conditions as specified in the REGENX Rett and ALS License. Under the REGENX Rett and ALS License we grant a non-exclusive, worldwide, royalty-free, transferable, sublicenseable,