Express treatment of prostate cancer, Pfizer PARP inhibitor combination therapy reached the main clinical endpoint of Phase 3

Pfizer today announced that its combination therapy of PARP inhibitor Talzenna (talazoparib) and Xtandi (enzalutamide) has achieved positive results
in the TALAPRO-2 Phase 3 clinical trial 。 Data analysis showed that the trial reached the primary endpoint, regardless of whether patients with metastatic castration-resistant prostate cancer (mCRPC) had tumors with homologous recombination repair (HRR) gene mutations, and this combination therapy achieved statistically significant and clinically significant improvements
in radiographically progressive survival (rPFS) compared with the placebo Gaenzalumine group.

Prostate cancer is the second most commonly diagnosed malignant tumor
in men worldwide.
Most men have localized prostate cancer at the time of diagnosis, which can be treated
with surgery or radiation therapy.
The growth of prostate cancer cells is androgen-dependent, so patients are initially sensitive to androgen deprivation therapy (ADT), while patients who still develop disease progression after persistent ADT develop mCRPC
.
It is estimated that 10-20% of prostate cancer patients will develop mCRPC
within 5-7 years of diagnosis.
The 5-year survival rate for mCRPC patients is about 30%, while the overall survival in clinical trials is about 3 years, which is expected to be even smaller
in the real world.

Talzenna is an oral polyadenosine diphosphate ribose polymerase (PARP) inhibitor
.
PARP plays a key role
in the DNA repair mechanism in cells.
PARP inhibitors have also been clinically proven to be effective in treating tumors
with BRCA mutant proteins that lack a DNA homologous recombination repair mechanism.
Talzenna was approved by the US FDA in 2018 for the treatment of locally advanced or metastatic breast cancer
with embryonic BRCA gene mutations and a human epidermal growth factor receptor 2 (HER2) negative.
Enzalumine is an androgen receptor inhibitor and is the standard therapy
for mCRPC, non-metastatic castration-resistant prostate cancer, and metastatic castration-sensitive prostate cancer.

TALAPRO-2 is a two-part, multicenter, double-blind, randomized, placebo-controlled Phase 3 clinical trial
.
A total of 1095 mCRPC patients were enrolled
.
This trial included two patient cohorts: Cohort 1 (including all types of patients, n=750) and Cohort 2 (patients with homologous recombination repair gene mutations, n=380).

The primary endpoint of the trial was radiographically progression-free survival, while the secondary endpoint included overall survival, objective response rate, duration of response, and prostate-specific antigen (PSA) response
.

Data analysis showed that in a cohort of all mCRPC patients, Talzenna achieved the primary endpoint of the trial compared with enzalumine plus placebo therapy, achieving statistically significant and clinically significant improvements in radiographically progression-free survival, and that the risk ratio (HR) was better than the predetermined value of 0.
696
.
The results also show that there is a trend towards improved overall survival of key secondary endpoints when performing data analysis, but these data are not yet mature
.
The same trend was found at other secondary endpoints
.
In addition, the safety profile demonstrated by the combination therapy of Talzenna and Enzalumine is consistent with the known safety information of the two drugs
.

Dr.
Chris Boshoff, Global Product Development Officer, Pfizer Oncology, said: "We are very pleased with the strong discovery of TALAPRO-2, and while we are still unable to draw any conclusions about the trial, the currently shown radiography-free survival is the longest observed in a similar randomized trial
.
These data support the feasibility
of a combination therapy between Talzenna and Enzalumide.
If approved, this could become the new standard of care for patients with mCRPC, regardless of whether the patient's homologous recombination repair gene carries a mutation
.
We look forward to discussing these data with global regulators
.
" ”

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