Dramatic improvement in survival for younger women with advanced breast cancer due to ribociclib

In brilliant news, it has been discovered that adding ribociclib to first-line endocrine therapy significantly improves both progression free and overall survival (PFS and OS) for premenopausal women with advanced breast cancer.

In an ASCO media release, ASCO Expert Harold J. Burstein, MD, PhD said: “Advanced breast cancer in premenopausal women can be very aggressive. It is important and encouraging to see a targeted therapy that significantly increases survival for younger women with this disease.” According to ASCO, advanced breast cancer is the leading cause of cancer death in women 20 to 59 years of age.

Breast Cancer Aotearoa Coalition chair Libby Burgess says the results of the clinical trial that provided these findings are stunning. “This strengthens the very clear case for having the CDK4/6 inhibitor class of medicines approved and funded for use in New Zealand for advanced breast cancer.”

The MONALEESA-7 clinical trial (an international, randomised phase III trial involving 672 patients and with 42 months follow-up) found that adding ribociclib to standard-of-care endocrine therapy significantly improved OS for premenopausal women with advanced HR-positive/HER2-negative breast cancer compared with endocrine therapy alone, ASCO says.

The women who received ribociclib lived a median of 23.8 months without the disease progressing compared with 13 months for women who received the placebo. After 42 months of follow-up, the survival rate was 70% for women who took the combination therapy compared with 46% for women who received endocrine therapy only.

Lead study author Sara A. Hurvitz, MD, Director of the Breast Cancer Clinical Research Program at UCLA Jonsson Comprehensive Cancer Center in Los Angeles, California says: “This is the first study to show improved survival for any targeted therapy when used with endocrine therapy as a first-line treatment for advanced breast cancer.”

A Korean study also reported at ASCO that premenopausal women receiving palbociclib with endocrine therapy had increased PFS compared with those who received chemotherapy (19.0 vs 11.3 months). This ‘Young PEARL’ study involved 189 patients and had follow-up of only 14 months, but the results suggested similar benefits to MONALEESA-7.

Three similar drugs, ribociclib (Kisqali®), palbociclib (Ibrance®) and abemaciclib (Kisqali®) inhibit the activity of cancer-cell promoting enzymes known as cyclin-dependent 4/6 kinases (CDK4/6). Expert commentator Angelo Di Leo stated that on the strength of the ASCO results the CDK4/6 inhibitors should be considered “the new standard of practice” for the first line treatment of premenopausal women with advanced HR-positive /HER2-negative breast cancer. Given that the same trend for benefit was seen for ribociclib and palbociclib, and considering other results for abemaciclib, he believes the three drugs of this class have equipoise, i.e. all have similar effectiveness.

When asked whether she thought the results would extend to postmenopausal women, Hurvitz pointed out that all young trial participants were rendered biologically postmenopausal with goserelin and stated she personally gives older women CDK4/6 inhibitors because “why not give (them) a chance of having a very long progression free survival”?

Other recent trials have shown that CDK4/6 inhibitors can also provide significant benefits when used as later line treatments for those whose metastatic breast cancer has advanced after first line endocrine therapy. 

Palbociclib is the first CDK4/6 inhibitor to be registered in New Zealand and in October 2018 Metavivors NZ took a petition to Parliament asking for this medicine to be funded. Medsafe has informed BCAC that ribociclib registration is imminent. 

Australia and Canada provide funded access to palbociclib and ribociclib while Scotland and the UK fund both these drugs as well as abemaciclib.  In New Zealand we are awaiting word from PHARMAC on whether and when our women will gain access to these vital medicines.

 

11 June 2019

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