Combined Andogen Blockade (CAB)

Mechanism of Action

LHRH-A* monotherapy does not suppress adrenal androgens.1

  • The majority of serum testosterone (approximately 90%-95%) is reduced by LHRH-As1
  • However, adrenal androgens are still present and may stimulate prostate cancer growth1
    • Approximately 40% of DHT (dihydrotestosterone), which is converted from adrenal androgens, is still present in the prostatic tissue and may stimulate prostate cancer growth1

* Luteinizing hormone-releasing hormone analog

Antiandrogens block action of androgens at the cellular level.1,2

The dual action of combined androgen blockade (CAB) provides androgen deprivation beyond LHRH-A alone.2,3

  • Antiandrogens block the binding of androgens at the receptor level in prostatic tissue2
  • LHRH-As inhibit the production of testicular androgens1

CAB therapy is medical [eg, LHRH-A] or surgical castration used concomitantly with an antiandrogen.2,3

  • Adding an antiandrogen after initiation of an LHRH-A has not been adequately studied4
Click here to see a more detailed view of the mechanism of action of CAB.

References:

  1. Labrie F, Belanger A, Simard J, Labrie C, Dupont A. Combination therapy for prostate cancer. Cancer. 1993;71(suppl):1059-1067.
  2. Garnick MB. Prostate cancer: screening, diagnosis, and management. Ann Intern Med. 1993;118;804-818.
  3. Loblaw DA, Mendelson DS, Talcott JA, et al. American Society of Clinical Oncology recommendations for the initial hormonal management of androgen-sensitive metastatic, recurrent, or progressive prostate cancer. J Clin Oncol. 2004;22:2927-2941.
  4. Data on file. DA-CAS-04, AstraZeneca Pharmaceuticals LP, Wilmington, Delaware.