Does 1st or 2nd place really matter? Review of treatment sequences in metastatic castrate-resistant patients

The authors aimed to determine the tumor activity and safety of cabazitaxel (Jevtana) and abiraterone (Zytiga) when used in metastatic castrate-resistant patients (patients whose cancer has spread and no longer responds to hormone therapy) who had previously received docetaxel (Taxotere, Docecad) treatment. 

Cabazitaxel and abiraterone are new drugs used to treat patients with metastatic castrate-resistant prostate cancer after they have received first line treatment (the first treatment option used in advanced prostate cancer) with the drug docetaxel. These drugs work by inhibiting cancer cell growth and hormones such as testosterone, which are produced in high levels in prostate cancer.

No previous study has investigated whether the order in which these drugs are received following failed docetaxel therapy makes a difference on cancer outcomes. 

This article aimed to determine whether using cabazitaxel – abiraterone (Cab – Abi; receiving cabazitaxel prior to abiraterone) or abiraterone – cabazitaxel (Abi – Cab; receiving abiraterone prior to cabazitaxel) has an effect on tumor activity and safety in metastatic castrate-resistant patients.

This study included 132 patients. 63 patients with a follow-up time of 23.7 months were given Cab – Abi  and 69 patients with a follow-up time of 21.8 months were given Abi – Cab.

In second line treatment (treatment given when initial treatment fails): Cab – Abi patients had a progression-free survival (time from treatment until the cancer spreads) of 5 months when compared to Abi – Cab patients who had 2.7 months. Biochemical progression-free survival (time taken for the prostate specific antigen levels – protein in the blood that is elevated in prostate cancer- to raise significantly) was 6.2 months in Cab – Abi patients compared to Abi – Cab patients who had 2.8 months.

When clinical response (changes in symptoms as a result of treatment) was measured, 12.7% of Cab – Abi patients experienced cancer progression compared to 27.5% of Abi – Cab patients. 7.9% of Cab- Abi patients experienced increased PSA levels and cancer progression compared to 30.4% of Abi – Cab patients.

In third line treatment (treatment given when both initial and following treatments fail): Cab – Abi patients had a progression-free survival of 2.4 months compared to 2.6 months in Abi – Cab patients. Biochemical progression-free survival was 2.7 months in Cab – Abi patients compared to 4.1 months in Abi – Cab patients. When clinical response was measured 38.7% of Cab – Abi patients experienced cancer progression compared to 30.9% in Abi – Cab patients. 27.9% of Cab – Abi patients experienced increased PSA levels and cancer progression in comparison to 21.2% of Abi – Cab patients.

Overall 60% of patients needed hospitalization. In second line treatment 15.9% of Cab – Abi patients needed more than two hospitalizations compared to 7.2% in Abi – Cab patients. The main event requiring hospitalization during treatment with cabazitaxel was febrile neutropenia (fever associated with immune system cell levels). Patients treated with Abi – Cab more often experienced pain during both treatments, while patients treated with Cab – Abi more often experienced urinary tract infections or urinary obstructions. 

The authors concluded that prior treatment with either drug did not prevent a response to the other, and that patient survival did not significantly change based on treatment sequence. 

Patient characteristics and treatments differed between the two groups and treatment choices were not standardized for each patient treated.

If you are considering treatment with either cabazitaxel or abiraterone please consult your doctor for further information on the best option for you.