Three Rare Disease Biotechs Raise Combined $675 Million in Public and Private Offerings

Rare Daily Staff

Homology Medicines raised $50 million through the pricing of an underwritten public offering to advance its lead gene therapy candidate HMI-102, currently in mid-stage development for the treatment of phenylketonuria.

Homology also granted the underwriter a 30-day option to purchase up to an additional $7.5 million of shares of its common stock, before deducting estimated offering expenses.

Phenylketonuria (PKU) is a rare inborn error of metabolism caused by a mutation in the PAH gene. PKU results in a loss of function of the enzyme phenylalanine hydroxylase, which is responsible for the metabolism of phenylalanine (Phe), an amino acid obtained exclusively from the diet. If left untreated, toxic levels of Phe can accumulate in the blood and result in progressive and severe neurological impairment. Currently, there are no treatment options for PKU that target the underlying genetic cause of the disease. According to the National PKU Alliance, PKU affects nearly 16,500 people in the U.S. with approximately 350 newborns diagnosed each year. The worldwide prevalence of PKU is estimated to be 50,000 people.

Homology intends to use the net proceeds from the offering, in addition to its existing cash resources, to: continue to advance its lead gene therapy candidate HMI-102 for the treatment of PKU in adults through the ongoing phase 2 pheNIX clinical trial; to advance HMI-203, its gene therapy candidate for the treatment of Hunter syndrome, and HMI-103, its first gene editing candidate, which is for the treatment of PKU in the pediatric population, through IND-enabling studies and into clinical trials; advance its other pipeline programs through preclinical development; further expand its intellectual property portfolio; potentially further expand its manufacturing capacity; and for working capital and general corporate and administrative expenses.

Crinetics Pharmaceuticals raised $75 million through the pricing of an underwritten public offering to advance a pipeline of novel therapeutics for rare endocrine diseases and endocrine-related tumors.

Proceeds from the offering will be used to advance lead candidate paltusotine, an investigational, oral, selective nonpeptide somatostatin receptor type 2 biased agonist for the treatment of the rare growth disorder acromegaly, into a phase 3 program in acromegaly and a phase 2 trial for the treatment of carcinoid syndrome associated with neuroendocrine tumors. Proceeds will also be used to advance oral nonpeptide treatments for congenital hyperinsulinism, Cushing’s disease, congenital adrenal hyperplasia, and for working capital and general corporate purposes.    

Acromegaly is generally caused by a benign growth hormone secreting tumor in the pituitary. Excess growth hormone secretion causes excess secretion of IGF-1 from the liver, which causes bone and cartilage overgrowth, organ enlargement, and changes in glucose and lipid metabolism. The symptoms of acromegaly include abnormal growth of hands and feet and changes in shape of the bone and cartilage that result in alteration of facial features. Overgrowth of bone and cartilage and thickening of tissue leads to arthritis, carpal tunnel syndrome, joint aches, enlarged lips, nose and tongue, deepening of voice due to enlarged vocal cords, sleep apnea due to obstruction of airways and enlargement of heart, liver and other organs.

Finally, Ionis Pharmaceuticals raised $550 million in a private placement of convertible senior notes due 2026. Ionis also granted the initial purchasers of the notes an option to purchase up to an additional $82.5 million of notes, within the 13-day period beginning on, and including, the date on which the notes are first issued.

The notes will be general unsecured obligations of Ionis, will not bear regular interest and the principal amount of the notes will not accrete. The notes will mature on April 1, 2026, unless earlier converted or repurchased.

Ionis, a leader in antisense technology, recently announced the initiation of a phase 3 clinical trial of ION363 in patients with amyotrophic lateral sclerosis (ALS) with mutations in the fused in sarcoma gene (FUS). Patients with a mutation in the FUS gene develop a rare form of ALS, referred to as FUS-ALS, which is the most common cause of juvenile-onset ALS. There is substantial evidence that mutations in the FUS gene are responsible for a toxic gain of function that can lead to rapid, progressive loss of motor neurons in patients with FUS-ALS. ION363 is an investigational antisense medicine targeting the FUS RNA to reduce the production of the FUS protein.