Dr. Tang on EXTEND trial in oligometastatic prostate cancer

Chad Tang, MD, The University of Texas MD Anderson Cancer Center, discusses the phase 2 EXTEND trial (NCT03599765), which explored the impact of adding metastasis-directed therapy to intermittent hormone therapy in patients with oligometastatic prostate cancer.

Study participants were randomly assigned to receive 6 months of HT plus local therapy or 6 months of HT alone. Local therapy could have included radiation, surgery, or cryotherapy to all sites of oligometastatic disease; all received radiation treatment.

Results presented at the 2022 ASTRO Annual Meeting showed that at a median follow-up of 22.1 months, the median PFS had not yet been reached in those who received combined treatment (n = 43) vs 15.8 months in those who were given HT alone (n = 44). This translated to a 75% reduction in the risk of disease progression or death (HR, 0.25; stratified log-rank P < .001).¹

Video Transcript

EXTEND is a basket study, which means we were looking at multiple histologies where each basket is powered by itself to look at a question. In this intermittent hormone therapy basket, patients with oligometastatic prostate cancer chosen to be on intermittent hormone therapy were randomized to radiation therapy versus not. Then the hormone therapy was stopped 6 months later, so you get a minimum of 8 months, because you needed 2-4 months before. This kind of mirrors an intermittent hormone regime. Then, patients were monitored and when their PSA rises, we call it progression when they meet certain thresholds, you put the patient's back on hormone therapy.

So, the primary end point was progression-free survival, which could be PSA or from radiographic assessment. We saw significant improvement in PFS with the combination which directly translate into a reduction in hormone therapy exposure. And secondarily, our most important secondary end point, eugonadal PFS, was also improved with the combination.

There may be some interest in the future in potentially utilizing not only metastasis-directed therapy, but also an intermittent hormone therapy regime, as these men can be often years without hormone therapy. It can convert a universally lethal disease when you compare these 2 modalities in select patients to one where it's a chronic disease. And not only that, but there will be substantial amounts of time with a chronic disease when you get to recover your testosterone and all men benefit from that because not only does it prevent all these side effects, such as hot flashes, night sweats, and loss of libido, it also allows patients to avoid some of the increased risks from hormone therapy, such as an increased cardiovascular risk, risk of stroke, adiposity, etc. So, I think it's a big win for patients if we can develop these chronic strategies that not only treat the disease with excellent control, but also maintain a quality of life.

This transcript has been edited for clarity.

Reference

1. Tang C, Sherry AD, Haymaker C, et al. Addition of metastasis-directed therapy to intermittent hormone therapy for oligometastatic prostate cancer (EXTEND): a multicenter, randomized phase II trial. Presented at: 2022 ASTRO Annual Meeting; October 23-26, 2022; San Antonio, TX. Abstract LBA 05