Nektar Therapeutics announced preliminary results from the first stage of a two-stage phase-2 clinical study evaluating NKTR-102 in women with platinum-resistant ovarian cancer. In the first stage of the study, 39 patients enrolled with platinum-resistant disease were evaluable for the primary endpoint of overall response rate using Gynecologic Cancer InterGroup (GCIG) criteria, i.e., a combination of response by tumour imaging (RECIST) and/or ovarian cancer biomarker (CA-125) criteria(1).

The first stage of the NKTR-102 phase-2 study showed an overall GCIG response rate of 32 per cent (6/19) in the once every 14 days (q14 day) dose schedule and 35 per cent (7/20) for the once every 21 days (q21 day) dose schedule. Confirmed objective response rates using RECIST were 21 per cent (4/19) and 22 per cent (4/18) for the q14 day and q21 day dose schedules, respectively. CA-125 response rates were 31 per cent (5/16) and 38 per cent (6/16), for each dose schedule, respectively. The phase-2 study has now completed enrolment with a total of 71 patients. Approximately one-third of the patients in the study remain on NKTR-102 treatment, including a number of patients in the first stage of the study.

"The early and dramatic reductions in CA-125 in many of the patients with platinum-resistant and refractory ovarian cancer indicate that NKTR-102 has great therapeutic potential," said professor Dr Ignace Vergote, head of the Department of Obstetrics and Gynaecology and Gynaecologic Oncology at the Catholic University of Leuven, European Union and Lead Investigator of the NKTR-102 study. "NKTR-102 is one of the most promising agents for platinum-resistant ovarian cancer I have seen in 25 years, as evidenced by the number of women in the study with tumor response and rapid biochemical response. This drug warrants further definitive Phase 3 testing as quickly as possible. The investigators look forward to presenting the final data at an upcoming scientific meeting."

The most commonly observed grade 3 or grade 4 side effects in the study to date (every 14 day/every 21 day dose schedule) were diarrhoea (29%/10%) and neutropenia (14%/10%).

"This population of heavily pre-treated patients, which includes a high proportion of women with platinum-refractory disease, is among the most challenging to treat in oncology," said Lorianne Masuoka, senior vice president and chief medical officer. "Almost half of the patients in the first stage of our study had platinum-refractory disease, having progressed within three weeks of their last platinum regimen. We are highly encouraged by the compelling efficacy seen to-date in the patients from the first stage of our study. This efficacy is accompanied by a favourable safety profile with regard to both GI side effects and neutropenia."

Nektar is developing NKTR-102, a topoisomerase I inhibitor-polymer conjugate with reduced peak concentrations and a continuous concentration profile.

Nektar Therapeutics is a biopharmaceutical company developing novel therapeutics based on its PEGylation and advanced polymer conjugation technology platforms.