SWOG Presents 30 Abstracts at ASCO 2023

Primary results from SWOG trials S1011, S1826, S1714, and S1929, along with results of an analysis from the S1609 DART trial, have been accepted for oral presentations (including a plenary presentation for S1826), and results to be presented in those sessions will be shared publicly during the meeting. 

Here are highlights from some of the other SWOG work to be presented at ASCO 2023. 

• Primary results of the phase III SWOG S1216 clinical trial in 1,313 patients with metastatic hormone-sensitive prostate cancer were published last spring, but this year’s ASCO meeting includes results from several analyses of data and biospecimens from this study. 
  A secondary analysis of S1216 data found that the group of patients whose prostate-specific antigen (PSA) levels at 3 months or 7 months showed a complete or partial response had a significantly higher five-year overall survival rate than did the group of patients whose PSA levels showed no response. This association held for patients on both of the trial’s treatment arms. The authors call for further research to determine the extent to which 3-month or 7-month PSA response could be used as a surrogate endpoint for overall survival in clinical trials. Mamta Parikh, MD, MS, of the University of California – Davis Comprehensive Cancer Center, presents the findings in an ASCO poster session June 3, 8 – 11 am CT (abstract 5074).

• A planned analysis of a subset of S1216 patients whose prostate cancer had spread to their bones (bone metastases) found that elevated levels of selected biomarkers that indicate bone loss or bone formation were associated with shorter patient lifespans. The researchers analyzed blood samples collected at baseline and found that levels of bone biomarkers, both by themselves and in combination with certain patient and tumor characteristics, identified unique subsets of men with differential overall survival outcomes, with median survival times ranging from 2.3 years to 7.5 years. Primo N. Lara, Jr., MD, director of the University of California – Davis Comprehensive Cancer Center, will present the results in an ASCO poster session June 3, 8 – 11 am CT (abstract 5048).

• Among men with metastatic hormone-sensitive prostate cancer enrolled to the SWOG S1216 trial, patients identifying as Black had median overall survival and progression-free survival times that were similar to those for men who self-identified as White, despite being likely to have presented with more aggressive disease. The authors suggest that equitable access to care may eliminate historical differences in outcomes between Black and White patients with prostate cancer. Nicolas Sayegh, MD, of the Huntsman Cancer Institute at the University of Utah, will present the results in a poster session June 3, 1:15 – 4:15 pm CT (abstract 6532).

• An analysis of the prognostic value of circulating tumor cell (CTC) counts in patients with metastatic hormone-sensitive prostate cancer (mHSPC) on the SWOG S1216 trial reports that CTC count at the start of treatment was highly prognostic of progression-free survival and overall survival, as well as of prostate-specific antigen (PSA) response. The findings suggest baseline CTC count may be a valuable prognostic biomarker in men starting treatment for mHSPC, helping identify those patients likely to respond favorably to treatment and those likely to have longer overall survival times. Dr. Amir Goldkorn, of USC Norris Comprehensive Cancer Center, presents the findings in an ASCO poster session June 3, 8 – 11 am CT (abstract 5080).

• Also from Dr. Amir Goldkorn’s lab comes a report on the first genomic sequencing panel that performs parallel analysis of single circulating tumor cells (CTCs) and circulating tumor DNA (ctDNA) from the same blood sample to detect variants relevant to prostate cancer. Known as HERCULES, the panel was developed in collaboration with Thermo Fisher Scientific and validated using samples from patients enrolled to the SWOG S1802 trial in metastatic prostate cancer. Such a tool represents an important breakthrough, as tracking genomic changes over time in metastatic prostate cancer can help guide patient treatment and predict disease outcomes. Daniel Bsteh, PhD, of USC Norris Comprehensive Cancer Center, will present the results in a poster session June 3, 8 – 11 am CT (abstract 5036).

• SWOG’s S1609 DART (Dual Anti-CTLA-4 & Anti-PD-1 blockade in Rare Tumors) basket trial in rare cancers, which tested the combination of ipilimumab and nivolumab in 798 patients with 53 different types of rare tumors, reports a subset of prolonged responses in a cohort of 16 patients with vulvar cancers (cohort 35). In those patients, the immunotherapy combination prompted 1 complete response, 2 partial responses, and an additional unconfirmed partial response. Progression-free survival times in these 4 patients ranged from 209 days to 1,022 days. The overall clinical benefit rate (no disease progression for at least 6 months) in the 16 patients with vulvar cancers was 31.3 percent (5 of 16 patients). Young Kwang Chae, MD, MPH, MBA, of Northwestern University Feinberg School of Medicine and Robert H. Lurie Comprehensive Cancer Center, will present these results in a poster discussion session June 5, 1:15 – 4:15 pm and 4:30 – 6 pm CT (abstract 5517).

These studies have been supported by the NCI, part of the NIH, led by SWOG, and conducted by the NIH-funded NCI National Clinical Trials Network (NCTN) and/or NCI Community Oncology Research Program (NCORP). Various NCI pharmaceutical collaborators provided support for these studies.  

S1216 was funded by the NIH/NCI through grants CA180888, CA180819, CA180820, and CA180821 and in part by Millennium Pharmaceuticals, Inc. (Takeda Pharmaceutical Company Ltd).

Study S1609 was funded by the NIH/NCI through grants U10CA180888, U10CA180819, U10CA180820, U10CA180868, and was supported in part by Bristol Myers Squibb Company through a Cooperative Research and Development Agreement between the company and the NCI.