Adding Imfinzi (durvalumab) — alone or in combination with tremelimumab — to standard first-line chemotherapy significantly delayed disease progression or death in people with metastatic non-small cell lung cancer (NSCLC), compared with chemotherapy alone, according to interim data of a Phase 3 study.
AstraZeneca’s Imfinzi and the investigational tremelimumab are two immune checkpoint inhibitors designed to boost the body’s anti-tumor response. They target proteins involved in mechanisms used by cancer cells to evade immune system attack. Imfinzi targets the PD-L1 protein on cancer cells, and tremelimumab targets the CTLA-4 protein on T-cells — immune cells involved in the fight against cancer.
The randomized, open-label, global POSEIDON Phase 3 trial (NCT03164616) is evaluating whether adding Imfinzi — alone or in combination with tremelimumab — to standard first-line chemotherapies induces greater therapeutic benefits than chemotherapy alone in people with metastatic NSCLC.
The study enrolled 1,000 patients with either non-squamous or squamous disease, the full range of PD-L1 levels in cancer cells, and no tumor mutations in the EGFR or ALK genes. Participants were randomly assigned to receive one of three treatment options: a combination of Imfinzi with one of five platinum-based chemotherapy regimens (double combo); Imfinzi with tremelimumab and chemotherapy (triple combo); or chemotherapy alone.
Those receiving Imfinzi were treated with 1,500 mg, alone or with 75 mg of tremelimumab, every three weeks, in combination with four cycles of chemotherapy. This was followed by maintenance therapy with Imfinzi every four weeks until disease progression. Patients in the chemotherapy-only group were given up to six cycles of chemo, with some allowed to receive Alimta (pemetrexed) maintenance thereafter.
POSEIDON’s primary goals include the assessment of whether Imfinzi combined with chemotherapy induces greater clinical benefit than chemotherapy alone in terms of progression-free survival (PFS) — the time a patient lives without signs of disease progression — and overall survival. Key secondary goals include similar assessments for the combination of Imfinzi, tremelimumab, and chemotherapy.
According to interim data now announced by AstraZeneca, patients treated with Imfinzi and chemotherapy had a statistically significant and clinically meaningful delay in disease progression or death, compared with those on chemotherapy alone.
The triple combo induced similar progression-free survival benefits, with the trial meeting its PFS primary and secondary goals.
Imfinzi’s safety profile was consistent with that reported in previous trials. The combination of Imfinzi, tremelimumab, and chemotherapy showed a broadly similar safety profile to Imfinzi combined with chemotherapy, with no increase in the proportion of patients discontinuing treatment.
“The POSEIDON trial provides evidence of the efficacy of Imfinzi in patients with [metastatic] non-small cell lung cancer. Clinical benefit was observed in a trial population that included a high proportion of patients with squamous disease and multiple choices of chemotherapy regimens,” José Baselga, AstraZeneca’s executive vice president of oncology research and development, said in a press release.
“Additionally, the potential to add tremelimumab to Imfinzi and chemotherapy may present an important treatment approach in this challenging setting, especially taking into consideration the favorable safety profile,” Baselga added.
The trial, which is being conducted in 153 centers across 19 countries — including the U.S., Germany, Poland, Mexico, China, Korea, Peru, Brazil, and South Africa — will continue to assess the safety and effectiveness of these treatment regimens.
Data on the additional primary goal of overall survival are expected by 2020.
AstraZeneca plans to submit POSEIDON’s results for presentation at a future medical meeting and share them with health authorities.
Imfinzi is approved in more than 40 countries, including the U.S., the U.K., and Japan, for treatment of patients with inoperable locally advanced NSCLC. It is given to people whose disease has not progressed after platinum-based chemotherapy and radiotherapy.
The treatment is being evaluated as a stand-alone therapy, or in combination with tremelimumab and chemotherapy in Phase 3 trials of small- and non-small-cell lung cancer, bladder cancer, liver cancer, head and neck cancer, cervical cancer, and biliary tract cancer, as well as other solid blood cancers.
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