Addyi (flibanserin), a drug that helps balance chemical messengers in the brain, led to improvements in sexual desire (libido), arousal and satisfaction, less pain and better health-related quality of life for premenopausal women using hormone therapy for breast cancer, according to research presented at the 2023 American Society of Clinical Oncology (ASCO) Annual Meeting.

“Decreased libido is an extremely prevalent, undertreated and distressing symptom in women with breast cancer on endocrine therapy,” Shari Goldfarb, MD, of Memorial Sloan Kettering Cancer Center, said in a company press release. “Flibanserin should be offered to women with breast cancer with bothersome and medication-induced decreased libido. Having a medication to treat this often unaddressed issue will improve the quality of life and sexual function of millions of women with breast cancer.”

Women with breast cancer commonly report sexual health problems ranging from decreased sexual desire to painful intercourse. Cancer and its treatment can affect sexual function in many ways. Endocrine therapy that blocks the action of the sex hormones estrogen and progesterone can slow the growth of hormone-dependent cancer, but it can also interfere with sexual function. Some types of chemotherapy and other drugs can also affect libido and sexual function. Changes in appearance—including hair loss, weight gain and surgical removal of the breasts—can affect self-esteem, resulting in decreased interest in sex. Having cancer can also lead to depression, anxiety and stress.

Goldfarb and colleagues evaluated Addyi in premenopausal women receiving hormone therapy for breast cancer who were experiencing low libido, or hypoactive sexual desire disorder.

Addyi, from Sprout Pharmaceuticals, is thought to work by altering levels of the neurotransmitters serotonin (associated with reduced sexual desire), dopamine (associated with feelings of pleasure, motivation and reward) and norepinephrine (which promotes alertness and plays a role in the fight-or-flight response). The drug was approved in 2015 to treat hypoactive sexual desire disorder in premenopausal women without other medical or psychiatric conditions. Addyi is generally safe, but it can cause side effects, including low blood pressure, dizziness, drowsiness and fainting, especially when used with alcohol or certain other medications.

This small study (NCT03707340) included 37 participants with Stage 0 (preinvasive or carcinoma in situ) to Stage III (spread to nearby lymph nodes or structures but not distant organs) breast cancer. The average age was 49 years, and they had been on hormone therapy for at least three months.

The study participants took Addyi once daily at bedtime for six months and were followed for about one year. They underwent medical exams and answered questionnaires at baseline and at weeks 4, 8, 16, 24 and 52. They were evaluated using validated patient-reported measures such as the Female Sexual Function Index, Pittsburgh Sleep Quality Index, Patient-Reported Outcomes Measurement Information System (PROMIS) and EQ-5D health-related quality of life index.

Women treated with Addyi saw statistically significant improvements in sexual desire, arousal, lubrication, orgasm and satisfaction, the researchers reported. Participants had an average libido score of 1.7 (on a scale of 1 to 5) at baseline, which increased to 2.8 at week 24 and fell back to 2.5 after stopping the drug. The average sexual satisfaction score rose from 1.6 at baseline to 2.6 at week 24, and the sexual confidence score more than doubled, from 1.2 to 2.5. Scores for the ease and frequency of orgasm increased from an average of 1.4 at baseline to 2.6 and 2.9, respectively, at week 24. What’s more, patients reported less pain and distress during sex and an increased number of sexually satisfying events.

In addition, average sleep duration increased from 6.7 to 7.7 hours per night at week 24 but fell below the baseline level, to 5.5. hours, after Addyi was discontinued. The average overall health status score rose from 78 out of 100 at baseline to 93 at week 24, but this also fell back, to 82, after the drug was stopped.

The researchers concluded, “Flibanserin is an effective treatment option for women with breast cancer,” but added that a larger randomized placebo-controlled study is still needed to further evaluate the medication for breast cancer patients with medically induced decreased libido.

“While we continue to make strides in the treatment of breast cancer, the side effects, especially sexual dysfunction in younger women, often remain unaddressed in the clinical setting,” said ASCO expert Erica Mayer, MD, MPH, of the Dana-Farber Cancer Institute. “This study offers an insight into the role of flibanserin in tackling this sensitive but common issue, showing an improvement in sexual dysfunction in patients taking the medication. Although the findings are based on a small cohort, they serve as a catalyst for a larger, robust and comprehensive study to further examine the potential of this agent in improving the overall well-being of breast cancer patients.”

Click here to ready the study abstract.
Click here for more reports from ASCO 2023.