PFS Improved in Frontline Squamous NSCLC with Atezolizumab Plus Chemo

Sandra Horning, MD

Sandra Horning, MD

According to topline findings from the phase III IMpower131 trial, the addition of atezolizumab (Tecentriq) to frontline carboplatin and nab-paclitaxel (Abraxane) delayed progression or death compared with chemotherapy alone for patients with advanced squamous non—small cell lung cancer (NSCLC). These results were announced by Genentech (Roche), the manufacturer of the anti–PD-L1 agent.

Coprimary endpoints for the IMpower131 study were progression-free survival (PFS) and overall survival (OS). A statistically significant OS improvement was not observed at the interim analysis. The study is now continuing according to its design and no new safety signals emerged with the atezolizumab combination. Roche reported that findings will be submitted for presentation at an upcoming oncology meeting.

“Squamous non-small cell lung cancer is difficult to treat and there have been limited new treatment options over the last few decades. We will share the IMpower131 results with global health authorities and we look forward to seeing more mature overall survival data,” Sandra Horning, MD, chief medical officer and head of Global Product Development at Roche, said in a statement.

The multicenter, open-label phase III IMpower131 study randomized 1021 chemotherapy-naïve patients with stage IV squamous NSCLC to upfront treatment with atezolizumab, carboplatin, and paclitaxel (arm A); atezolizumab, carboplatin, and nab-paclitaxel (arm B); or the control arm of carboplatin and nab-paclitaxel (arm C).

The induction phase for arm A comprised 4 or 6 cycles of atezolizumab plus carboplatin and paclitaxel, administered on day 1 of each 21-day cycle. Patients received maintenance atezolizumab every 3 weeks as long as a clinical benefit was observed with no disease progression.

For arm B, the induction phase involved 4 to 6 cycles of atezolizumab, carboplatin, and nab-paclitaxel. Patients were given atezolizumab and carboplatin on day 1 of each 21-day cycle, followed by the same maintenance atezolizumab regimen used for arm A.

Induction for arm C comprised 4 or 6 cycles of carboplatin and nab-paclitaxel. Patients were given carboplatin on day 1 of each 21-day cycle, and nab-paclitaxel was then administered on days 1, 8, and 15 of each 21-day cycle. Maintenance phase consisted of best supportive care.

Previously reported results from a phase Ib trial presented at the 2015 World Conference on Lung Cancer demonstrated the promise of combining frontline atezolizumab with chemotherapy in patients with metastatic NSCLC.¹Patients received atezolizumab at a dose of 15 mg/kg IV every 3 weeks in addition to 1 of 3 chemotherapy doublets: carboplatin paired with paclitaxel, pemetrexed (nonsquamous histology only), or nab-paclitaxel. Treatment continued for 4 to 6 cycles, and was followed by atezolizumab maintenance therapy until disease progression. Patients had the option of pemetrexed maintenance in that arm of the trial.

Determined by RECIST criteria, the overall response rate were reported for 58 patients, 41 of whom were evaluable for response. The patients had a median age of 65, and 79% of the cohort had nonsquamous histology. 

Overall, 26 (63.4%) of the 41 evaluable patients met the criteria for objective response. Four of 8 (50%) patients in the atezolizumab plus carboplatin/paclitaxel cohort achieved objective responses (all partial responses). The combination of atezolizumab, carboplatin, and pemetrexed induced a response in 13 (76.5%) of 17 patients (all partial responses). Responses also occurred in 9 (56%) of 16 patients who received carboplatin and nab-paclitaxel in addition to atezolizumab.

Data reported in December at the ESMO Immuno Oncology Congress from the phase III IMpower150 trial demonstrated that the frontline combination of atezolizumab (Tecentriq), bevacizumab (Avastin), carboplatin, and paclitaxel delayed progression or death by 38% compared with bevacizumab and chemotherapy alone for patients with advanced nonsquamous NSCLC.²

The atezolizumab regimen showed a median PFS of 8.3 months compared with 6.8 months with bevacizumab and chemotherapy alone (HR, 0.62; 95% CI, 0.52-0.74;P<.0001). The 12-month PFS rate was 37% with the atezolizumab-containing regimen and 18% with the bevacizumab/chemotherapy regimen.

In a preliminary examination of OS, there was a 22.5% reduction in the risk of death with the atezolizumab combination compared with bevacizumab and chemotherapy alone. After a minimum follow-up of 9.5 months, the median OS was 14.4 (95% CI, 12.8-17.1) versus 19.2 months (95% CI, 16.8-26.1), in favor of the atezolizumab group (HR, 0.775; 95% CI, 0.619-0.970;P= .0262). The next OS analysis will take place in the first half of 2018.

References:

1. Camidge R, Liu SV, Powderly J, et al. Atezolizumab (MPDL3280A) combined with platinum-based chemotherapy in non—small cell lung cancer (NSCLC): a phase Ib safety and efficacy update. Presented at: 16th World Conference on Lung Cancer; September 6-9; Denver, CO. Abstract 02.07.
2. Reck M. Primary PFS and safety analyses of a randomized Phase III study of carboplatin + paclitaxel +/&minus; bevacizumab, with or without atezolizumab in 1L non-squamous metastatic NSCLC (IMpower150).Annals of Oncology, 2017;28(11). Abstract LBA1_PR.

The current analysis only looked at results from arm B versus arm C in comparison. The study design stipulates that the nab-paclitaxel arm (B) must first demonstrate a statistically significant OS benefit versus the control arm (C) before the paclitaxel arm (A) can be comparied to the control arm for PFS and OS.