Pfizer and Astellas' Xtandi Shows Superior Survival Data in mHSPC, Strengthening Lead Over J&J

Compiled by | Tom Li

Pfizer and Astellas have been engaged in fierce competition with Johnson & Johnson (J&J) in the prostate cancer field, with all companies striving to secure additional indication approvals and drive sales. However, the recently released pivotal overall survival data for Xtandi by Pfizer and Astellas may help further enhance the drug's market prospects among men with metastatic hormone-sensitive prostate cancer.

Based on data presented by the two companies at the 2021 European Society for Medical Oncology (ESMO) Virtual Congress, the final analysis of the Phase 3 ARCHES trial by Pfizer and Astellas evaluating the oral prostate cancer drug Xtandi in combination with androgen deprivation (AD) for the treatment of patients with metastatic hormone-sensitive prostate cancer demonstrated that Xtandi significantly prolonged survival compared to androgen deprivation therapy alone.

The study demonstrated that, compared with androgen deprivation therapy (ADT) alone, the combination of ADT and Xtandi reduced the risk of death by 34% in patients with metastatic hormone-sensitive prostate cancer. At the 2-year follow-up, the reported overall survival rate was approximately 86% in the Xtandi group (n=574) compared to 82.3% in the placebo group (n=576). The difference in overall survival between the two groups widened further at the 3-year follow-up, with a survival rate of 77.8% in the Xtandi group versus 69% in the placebo group. By year 4, the overall survival rate was 70.6% in the Xtandi group, compared to only 57% in the placebo group. Additionally, the median treatment duration was 40.2 months in the Xtandi group, compared to approximately 14 months in the placebo group.

Xtandi, jointly developed and marketed by Astellas and Pfizer, is an androgen receptor signaling inhibitor that requires only once-daily oral administration. Xtandi directly targets the androgen receptor (AR) and exerts its therapeutic effects within the AR signaling pathway. These positive data may further help Pfizer and Astellas outperform competitors such as Johnson & Johnson’s Erleada and Zytiga in the prostate cancer treatment landscape. To date, Xtandi’s sales have already surpassed those of its rivals, with the drug achieving $4.39 billion in sales last year, significantly outpacing Erleada’s $760 million. Meanwhile, due to competition from generic versions, Zytiga’s sales totaled only $2.4 billion in 2020, representing a decline of nearly 12% compared to 2019.

In June this year, Xtandi received a recommendation from the UK's National Institute for Health and Care Excellence (NICE) for use as a once-daily oral medication in combination with standard androgen deprivation therapy for the treatment of patients with metastatic hormone-sensitive prostate cancer (mHSPC). As a follow-on product to Johnson & Johnson's prostate cancer therapy Zytiga, Erleada is a novel non-steroidal androgen receptor (AR) inhibitor that blocks the action of androgens, thereby inhibiting tumor growth. In February 2018, the drug received its initial approval from the U.S. Food and Drug Administration (FDA) for the treatment of adult patients with non-metastatic castration-resistant prostate cancer (nmCRPC) at high risk of metastasis.

Following a prior rejection by the UK's National Institute for Health and Care Excellence (NICE), Johnson & Johnson's Erleada regained a positive recommendation from NICE in early September. The institute has now recommended the drug for the treatment of patients with non-metastatic hormone-refractory prostate cancer (nmHRPC) at high risk of metastasis, as well as those with metastatic hormone-sensitive prostate cancer (mHSPC).

In the Chinese market, Xtandi was officially approved in late November 2019 for the treatment of adult patients with metastatic castration-resistant prostate cancer (mCRPC) following failure of androgen deprivation therapy, who are asymptomatic or mildly symptomatic and have not received chemotherapy. Currently, prostate cancer is the second most common malignancy in men worldwide and has also become the most common urological malignancy among men in China.

Source: ESMO: Pfizer, Astellas' latest Xtandi survival data may shore up prostate cancer lead over J&J