Support for adding atezolizumab to chemotherapy in advanced squamous NSCLC
medwireNews: Results from the IMpower131 trial show that patients with stage IV squamous non-small-cell lung cancer (NSCLC) derive a significant progression-free survival (PFS) benefit from combining atezolizumab with chemotherapy.
As reported at the ASCO Annual Meeting 2018 in Chicago, Illinois, USA, the 343 chemotherapy-naïve participants who were randomly assigned to receive atezolizumab 1200 mg every 3 weeks alongside 4–6 cycles of carboplatin plus nab-paclitaxel had a significant 29% reduced risk for disease progression or death compared with their 340 counterparts given chemotherapy alone.
The median investigator-assessed PFS times were 6.3 and 5.6 months for the combination and chemotherapy alone groups, respectively, and the 12-month rate was doubled with the addition of atezolizumab, at 24.7% versus 12.0%, said presenting author Robert Jotte (Rocky Mountain Cancer Centers, Denver, Colorado, USA).
As such the trial met one of its co-primary endpoints, he added.
The PFS advantage afforded by atezolizumab was observed across all subgroups, including by age, smoking, and programmed cell death ligand 1 (PD-L1) status.
Jotte noted that even patients with PD-L1-negative tumors (tumor and immune cell scores of 0) benefitted from the addition of atezolizumab to chemotherapy, but the effect was more pronounced in those with high PD-L1 expression (tumor and immune cell scores of 3), with hazard ratios relative to chemotherapy alone of 0.81 and 0.44, respectively.
He said that an interim analysis for the other co-primary endpoint – overall survival – showed comparable results for the two treatment arms, but added that the data are not yet mature at this time, at a median follow-up of 17.1 months. The team expects to conduct another interim analysis later this year.
The incidence of all-cause and treatment-related adverse events (AEs) of grade 3 or 4 was higher in the combination than in the chemotherapy alone study arm, at 73% versus 66% and 68% versus 57%, respectively. This was also the case for all-cause grade 5 AEs, with corresponding rates of 9% and 4%, but the rate of grade 5 AEs attributable to treatment was the same, at 1% each.
Noting that participants in the atezolizumab group continued to receive the PD-L1 inhibitor as maintenance therapy, while those in the control group received just best supportive care, the presenter pointed out that “the frame for reporting was extended” in the atezolizumab arm, “which we believe is the explanation for the [higher all-cause] grade 5 toxicity.”
In conclusion, he said that overall survival continues to be followed up, as does a third arm of the study, in which 338 patients are receiving atezolizumab in addition to 4–6 cycles of carboplatin plus paclitaxel.
medwireNews is an independent medical news service provided by Springer Healthcare. © 2018 Springer Healthcare part of the Springer Nature group