AT WCLC 2016
VIENNA (FRONTLINE MEDICAL NEWS) – The investigational agent alisertib plus paclitaxel improved progression-free survival (PFS), compared with paclitaxel plus placebo, in a randomized, double-blind, phase II study of patients with relapsed or refractory small-cell lung cancer (SCLC).
The median PFS was 3.32 months with alisertib/paclitaxel and 2.17 months with paclitaxel/placebo, giving an overall 30% improvement with the combination (hazard ratio, 0.71; 95% confidence interval, 0.509-0.985; P = .038).
In patients who were resistant/refractory to reusing platinum-based chemotherapy at recruitment, an even greater benefit favoring the combination over the taxane treatment alone was achieved. Respective median PFS was 2.86 months vs. 1.64 months, with a hazard ratio of 0.659 (95% CI, 0.442-0.983; P = .037).
“c-Myc protein expression showed a strong association with improved PFS, despite the small number of evaluable patients,” study investigator Taofeek Owonikoko, MD, of Emory University, Atlanta, said at the World Conference on Lung Cancer.
Amplification and overexpression of c-Myc is a strong oncogenic driver in many cancers, he explained. Around 18%-31% of SCLCs overexpress the protein, and it is often found in patients with chemorefractory disease, he said.
In the study, longer PFS was achieved in patients treated with alisertib/paclitaxel than in those given placebo/paclitaxel if they were c-Myc positive (4.64 vs. 2.27 months; HR, 0.29). Conversely, patients who were c-Myc negative had a shorter PFS with the combination (3.32 vs. 5.16 months; HR, 11.8).
“A prospective study is needed to further validate the predictive value of c-Myc in the clinic,” Dr. Owonikoko said at the meeting, which was sponsored by the International Association for the Study of Lung Cancer.
Alisertib is an aurora A kinase inhibitor that has already been shown to have antitumor activity in patients with solid tumors, including those with SCLC (Lancet Oncol. 2015;16:395-405).
The current phase II study was designed to evaluate the efficacy and safety of alisertib in combination with paclitaxel, compared with placebo plus paclitaxel, in a larger population of patients with SCLC who had relapsed within 6 months or did not respond to standard first-line, platinum-based chemotherapy.
Treatment was given in 28-day cycles, with patients randomized to the combination receiving alisertib at an oral, 40-mg, twice-daily dose on days 1-3, 8-10, and 15-17 and paclitaxel administered intravenously at a dose of 60 mg/m2 IV on days 1, 8, 15. Patients randomized to the control arm received a matched placebo plus paclitaxel given on the same days but at a dose of 80 mg/m2.
Overall, 178 patients were randomized, with a mean age of 62 years, and just over half (57%) were men.
Numerically higher objective response rates (22% vs. 18%), disease control rates (77 vs. 67%), and overall survival (6.87 vs. 5.58 months) also were seen with the combination over paclitaxel alone, although they did not achieve statistical significance.
Additional toxicities were observed with the combination treatment versus paclitaxel. Many of these were to be expected, Dr. Owonikoko said. Almost all (99% vs. 96%) of patients reported some type of adverse event, of which 75% and 51% were grade 3 or higher, respectively. Common any-grade adverse effects were diarrhea (59% vs. 20%), neutropenia (49% vs. 8%), anemia (44% vs. 20%), and fatigue (44% vs. 33%).
These toxicities, however, did not appear to affect patients’ quality of life, Dr. Owonikoko said, as comparable changes in quality-of-life scores using the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire C30 instrument were observed. There was even an indication that patients taking alisertib/paclitaxel might have improved lung-related symptoms, such as shortness of breath and worsening cough.
The treatment of SCLC, particularly in the second-line setting, remains challenging, observed the invited discussant for the trial Jens Benn Sørensen, MD, of the Finsen Centre at Rigshospitalet, Copenhagen.
“There have been no major improvements in the last decade and there are no targeted agents approved for use,” Dr. Sørensen said. Although that is not for lack of trying, he qualified.
When first-line therapies fail, the guideline-recommended option is to put patients back on platinum-based chemotherapy if they were sensitive to such chemotherapy. If not, then topotecan is often an appropriate, reasonably tolerated option.
“The clinical relevance of second-line paclitaxel/alisertib in all comers is questionable,” he said. The PFS improvement of 1.2 months in this phase II study seems “mostly at the same level” when comparing trials of second-line, single-agent topotecan.
“However, the use of c-Myc as a predictor for efficacy seems very promising and should clearly be explored,” Dr. Sørensen noted.
He also suggested that it might be interesting to look into the combination of topotecan and alisertib versus topotecan alone in c-Myc-positive patients.
The study was funded by Millennium Pharmaceuticals, a wholly owned subsidiary of Takeda Pharmaceutical Company. Dr. Owonikoko disclosed consulting for Takeda and several other pharmaceutical companies. Dr. Sørensen did not have disclosures.