ASCO 2023 Meeting Report — Genitourinary Cancers

The 2023 American Society of Clinical Oncology (ASCO) annual meeting, held June 2 to 6 in Chicago, highlighted important advances in treatment across a broad spectrum of malignancies. Here, Associate Editor Dr. Robert Dreicer reviews several key trials in in prostate and renal cancers.

For men with de novo metastatic, castration-sensitive prostate cancer and a low metastatic burden, adding radiotherapy to standard-of-care treatment (defined as androgen-deprivation therapy plus docetaxel) plus abiraterone acetate and prednisone (AAP) was associated with significantly improved progression-free survival (PFS) — but not overall survival (OS) — according to findings from the industry-supported, phase 3 PEACE-1 trial (abstract LBA5000).

Nearly 1200 men were randomized to one of four treatment regimens:

• Standard of care
• Standard of care plus AAP
• Standard of care plus radiotherapy
• Standard of care plus AAP plus radiotherapy

In a planned analysis among roughly 500 men with low-volume disease (up to 3 bone metastases, with or without lymph node involvement), after a median 6 years' follow-up, 303 radiographic PFS events and 214 OS events occurred. Among the results for PFS:

• Radiotherapy added to standard of care did not appear to improve PFS compared with standard of care alone.
• Radiotherapy added to standard of care plus AAP was associated with significantly longer PFS than standard of care alone, at a median of 7.5 versus 3.0 years.
• Standard of care plus AAP — and without radiotherapy — did not significantly improve PFS compared with standard of care alone.

With respect to OS, radiotherapy did not significantly improve outcomes, although patients who received standard of care plus AAP plus radiotherapy seemed to fare best (median OS not reached).

Summary by Amy Herman, Staff Writer

COMMENT — Dr. Robert Dreicer

The results of this study continue to suggest some modest benefit from the addition of radiotherapy in the setting of low-volume, castration-sensitive, metastatic prostate cancer. As noted by the discussant, the failure to observe an OS benefit may be secondary to the significant improvement in the activity of the systemic therapies administered.

Adding atezolizumab to cabozantinib in the “salvage” setting offered no survival advantage in patients with locally advanced or metastatic clear cell or non–clear cell renal cancer, according to findings from the industry-sponsored, phase 3 CONTACT-03 trial (abstract LBA4500).

In the open-label trial, nearly 525 patients with disease progression during or after prior immune checkpoint inhibitor therapy were randomized to treatment with the vascular endothelial growth factor (VEGF)–tyrosine kinase inhibitor cabozantinib alone or combined with the PD-L1 inhibitor atezolizumab.

At a median follow-up of 15.2 months, 65% of patients in the cabozantinib/atezolizumab arm and 64% in the cabozantinib arm had disease progression or died. Median progression-free survival was 10.6 and 10.8 months, respectively. Overall survival also did not differ between groups. Serious adverse events were more common with cabozantinib/atezolizumab than with cabozantinib alone (48% vs. 33%).

Summary by Cara Adler, Staff Writer

COMMENT — Dr. Robert Dreicer

The results of this prospective, phase 3 trial were unequivocally negative. Phase 2 data on cabozantinib/atezolizumab suggested a provocative level of activity — this trial reminds us that not everything that looks good in phase 2 trials pans out in phase 3.