Enobosarm May Characterize a Safe, New Hormone Therapy Solution for AR+, ER+ Metastatic Breast Cancer

Success from the period 2 G200802 trial (NCT02463032) confirmed that in individuals who been given enobosarm at a dose of 9 mg accomplished a clinical advantage price (CBR) of 32% (95% CI, 19.5%-46.7%). In a cohort of sufferers who gained 18 mg of the agent, the agent induced a CBR of 29% (95% CI, 17.1%-43.1%).

Furthermore, patients who experienced more than 40% AR staining knowledgeable an in general reaction rate (ORR) of 50% and a CBR of 79% 21% of individuals produced progressive illness. Individuals with an AR staining of less than 40% skilled an ORR of % and a CBR of 18%. Eighty-two % of sufferers in this group developed progressive disease.

“This is an intriguing and handy pathway, and one particular that is incredibly attractive to ladies,” Linden reported. “I invest a lot of time working with frustrations pertaining to AEs [experienced with] ER blockade and estradiol depletion. These are really real AEs for clients owning an alternate selection that does not [come with] these [toxicities] will be really remarkable and appealing for [patients].”

In an interview with OncLive® in the course of the 2021 ASCO Yearly Meeting, Linden, a medical professional at Seattle Most cancers Treatment Alliance a professor in the Division of Clinical Oncology at the University of Washington Faculty of Medication and a professor of the Scientific Research Division at Fred Hutchinson Most cancers Investigation Heart, discussed the potential for enobosarm in clients with metastatic breast cancer, data from a stage 2 demo examining its use, and following ways for the agent in the paradigm.

OncLive®: How may possibly AR-targeted brokers serve to get over mechanisms of resistance in patients with AR-beneficial, ER-optimistic metastatic breast most cancers?

Linden: The AR has been a recognised target in breast most cancers for a long time. Extra senior members of the training group know that we have provided testosterone or androgen blockers properly [in the past]. [The AR] is just another hormonal pathway that appears to be to be most related for [our patients with] ER-constructive [disease].

[We have seen a lot of hype for this strategy in patients with] triple-detrimental, AR-optimistic [disease] it is powerful that we might have a concentrate on for this team when we did not earlier believe that we did. Endocrine therapy is the oldest [approach] we have [in our arsenal], and a variety of endocrine agents are helpful. What is remarkable is that we could be equipped to leverage that pathway in a way that tends to make [treatment] pretty tolerable for our people.

What was the design of the stage 2 medical trial examining enobosarm?

The section 2 demo looked at a pair of distinct doses to get some knowledge with [the approach in] clients who had been intensely pretreated. Some sufferers do not will need a lot in phrases of treatment method they may well not even have to have a molecularly targeted agent in addition to endocrine therapy. Some clients are just good responders. That team is the one that we are truly on the lookout at in this review [we want] to give [these patients] an choice endocrine solution. Endocrine therapy is usually effectively tolerated but has been known [to cause] issues for people in the kind of menopausal indications, bone density loss, and arthralgias.

[Enobosarm] is a distinctive endocrine agent that does not have any of those adverse results [AEs], nor any of the other regrettable toxicities that higher-dose estrogen or progestins have experienced. [The agent also] does not have the [same] AEs [that have been observed with] androgen agonists. This is a good harmony of preventing the estrogen-deprivation AEs and delivering some favorable androgenic results, such as an enhancement in lean body mass.

What are the crucial takeaways from this trial?

It has been known that AR is co-expressed in many ER-constructive tumors, but definitely drilling down on the quantities is essential. We know what it means when [a patient is] hugely ER favourable vs weakly good. We know what it usually means when the progesterone receptor is very expressed or is not. In this [trial, we asked,] what does the stage of AR expression mean? Not astonishingly, it suggests [a patient is] likely to attain a improved reaction to this remedy simply because it is an AR-directed treatment.

How do you see this agent probably fitting into the procedure landscape?

The landscape is definitely complex correct now with so quite a few distinctive alternatives readily available. [Enobosarm may] be utilised as a solitary agent. I also believe that the agent will be made use of in concert with some of the molecularly qualified agents, these as CDK4/6 inhibitors.

None of us definitely know what to do following development on a CDK4/6 inhibitor. Need to [the patient] go on to obtain oral chemotherapy? Really should you change to single-agent hormonal therapy? Ought to you give the very same, or a distinct, CDK4/6 inhibitor with your future agent? [Enobosarm] will be thrown in the mix as a way to assume about what you could lover with. [The agent] will be a refreshing companion mainly because [it has] much less AEs, but it also [targets] a unique pathway.

Where by will long run study efforts be centered?

The drug is going to be tested in a period 3 analyze to try to get Fda approval for its use in [patients with] metastatic breast cancer. Also, [the agent] will [probably] be analyzed in synergy with CDK4/6 inhibitors, which really have changed the way we take care of this disorder and have improved response level, time to development, and survival.

Is there anything at all you would like to increase?

Possessing a treatment method that does not result in these AEs and can make [a patient] come to feel good, truly feel much better, and have a very little far more electricity is particularly interesting. Exhaustion is a substantial symptom for sufferers dwelling with cancer. [Enobosarm] is an extremely desirable drug since clients just want [to have better] excellent of daily life. We can not just prolong the quantity of lifestyle we have to have to also lengthen high-quality of daily life.


  1. Palmieri C, Linden HM, Birrell S, et al. Efficacy of enobosarm, a selective androgen receptor (AR) targeting agent, correlates with the degree of AR positivity in state-of-the-art AR+/estrogen receptor (ER)+ breast cancer in an international section 2 scientific research. J Clin Oncol. 202139(suppl 15):1020. doi:10.1200/JCO.2021.39.15_suppl.1020