Net loss for the three-month period ended June 30, 2018 was $8.1 million, or $0.29 basic and diluted net loss per ordinary share, as compared to $4.2 million, or $0.18 basic and diluted net loss per ordinary share for the three-month period ended June 30, 2017.
Six Months Ended June 30, 2018 and 2017
Research and development expenses were $14.1 million for the six months ended June 30, 2018, compared to $6.3 million for the six months ended June 30, 2017. The increase of $7.8 million resulted primarily from increases in program-related expenses of $3.4 million forNSR-REP1 and $2.5 million forNSR-RPGR, as well as a $2.7 million increase in personnel-related costs and a $0.9 million increase in the indirect research and development expenses. The increased expenses were partially offset by an increase of $1.6 million of research and development tax credits from the HMRC. Research and development personnel-related costs increased due to an increase in headcount to support our growth and to assist in the further development of our product candidates and pipeline. The increase in research and development personnel-related costs includes $0.8 million of additionalnon-cash share-based compensation compared to the same period in 2017.
General and administrative expenses were $6.1 million for the six months ended June 30, 2018, compared to $1.4 million for the six months ended June 30, 2017. The increase of $4.7 million is mainly due to a $3.7 million increase in personnel-related costs and $1.0 million increase in consulting and professional fees, including increased legal, accounting and audit fees and insurance costs. General and administrative personnel-related costs increased due to an increase in headcount to support our increased research and development activities, growth of our company, and our status as a public company. The increase in general and administrative personnel-related costs includes $1.1 million of additionalnon-cash share-based compensation compared to the same period in 2017.
Net loss for thesix-month period ended June 30, 2018 was $22.5 million, or $0.80 basic and diluted net loss per ordinary share, as compared to $7.7 million, or $0.33 basic and diluted net loss per ordinary share for thesix-month period ended June 30, 2017.
As of June 30, 2018, our cash, cash equivalents and marketable securities totaled $111.4 million, compared to $129.4 million at December 31, 2017. As of June 30, 2018, there were approximately 28.9 million ordinary shares outstanding.
About Nightstar
Nightstar is a leading clinical-stage gene therapy company focused on developing and commercializing novelone-time treatments for patients suffering from rare inherited retinal diseases that would otherwise progress to blindness. Nightstar’s lead product candidate,NSR-REP1, is currently in Phase 3 development for the treatment of patients with choroideremia, a rare, degenerative, genetic retinal disorder that has no treatments currently available and affects approximately one in every 50,000 people. Positive results from a Phase 1/2 trials ofNSR-REP1 were published inThe Lancet in 2014 and inThe New England Journal of Medicine in 2016. Nightstar’s second product candidate,NSR-RPGR, is currently being evaluated in a clinical trial known as the XIRIUS trial for the treatment of patients withX-linked retinitis pigmentosa, an inheritedX-linked recessive retinal disease that affects approximately one in every 40,000 people.