Dr. John Sweetenham shares highlights from Day 2 of the 2025 ASCO Annual Meeting, including new data on the treatment of ER+/HER2-negative breast cancer and potentially practice-changing results for patients with cutaneous squamous cell carcinoma at high risk of recurrence.
TranscriptDr. John Sweetenham: Hello, I'm Dr. John Sweetenham, your host of the ASCO Daily News Podcast, welcoming you to our special coverage of the 2025 ASCO Annual Meeting. Today, I'll be bringing you my takeaways on selected abstracts from Day 2 of the Meeting. My disclosures are available in the transcript of this episode.
Today's selection features important, new data on the treatment of ER-positive, HER2-negative breast cancer, the use of tumor treating fields in combination with chemotherapy for locally advanced pancreatic cancer, and potentially practice-changing results for patients with cutaneous squamous cell carcinoma at high-risk of recurrence.
Our first selected abstract is LBA1000. This important phase 3 study was presented by Dr. Erika Hamilton from the Sarah Cannon Research Institute in Nashville and evaluated the use of a novel agent, vepdegestrant, in patients with ER-positive/HER2-negative breast cancer, which had progressed after first-line endocrine therapy. Vepdegestrant is a selective oral PROTAC estrogen receptor degrader, which targets wild-type and mutant estrogen receptor through a novel mechanism of action which directly harnesses the ubiquitin-proteasome system to degrade ER. It has potential advantages over fulvestrant, a selective ER degrader which has to be administered intramuscularly and has limited benefit in patients who progress after endocrine therapy plus a CDK4/6 inhibitor.
Building on the encouraging results from the initial phase 1/2 study of vepdegestrant, Dr. Hamilton reported results from the VERITAC-2 global phase 3 trial, comparing this agent with fulvestrant. The patients in the study had already received treatment with hormone therapy and a CDK inhibitor and were randomly assigned to receive treatment with either vepdegestrant (313 patients) or fulvestrant (311 patients). The vepdegestrant was taken orally each day, while the fulvestrant was given intramuscularly on days 1 and 15 of the first cycle of treatment and day 1 of each subsequent treatment cycle. Patients were stratified by the presence of wild-type ER or ESR1 mutation. A total of 43.3% of patients had ESR1 mutations; 136 of those were in the vepdegestrant group and 134 in the fulvestrant group.
For patients with ESR1 mutations, vepdegestrant significantly increased progression-free survival compared with fulvestrant. For patients who received vepdegestrant, the median PFS was 5 months versus 2.1 months for those who received fulvestrant. The clinical benefit rate was 42.1% in the vepdegestrant group vs. 20.2% in the fulvestrant group. The overall response rate was 18.6% in the vepdegestrant group compared with only 4% in the fulvestrant group.
The PFS and response benefits of vepdegestrant were largely restricted to the population with ESR1 mutations. Overall survival data are currently immature. The safety profile was favorable, with fewer than 5% of patients having dose reductions or discontinuation due to toxicity. The most frequent toxicities were fatigue, nausea, and elevated transaminases.
The authors concluded that oral vepdegestrant demonstrates statistically significant and clinically meaningful improvement in progression-free survival compared with fulvestrant in this group of patients with ESR1-mutated ER+/HER2- advanced breast cancer who have progressed after endocrine therapy and a CDK inhibitor. Patients with recurrent disease in this context are now routinely tested for ESR1 mutations, and this agent is for sure a potential treatment option for them.
The next study on today's episode, LBA4005, reports on the use of tumor treatment fields for patients with locally advanced pancreatic cancer. Tumor treatment fields are electric fields which disrupt cell division and may also induce an enhanced immune response, using a non-invasive portable device attached to the skin, and are already approved for the treatment of some cancers, including GBM and non-small cell lung cancer. A previous phase 2 trial, PANOVA-2, confirmed the feasibility and safety of using this approach in combination with gemcitabine plus or minus nabpaclitaxel in pancreatic cancer.
In today's presentation, Dr. Vincent Picozzi from the Virginia Mason Medical Center in Seattle presented the results of the PANOVA-3 trial, a phase 3 study comparing gemcitabine and nabpaclitaxel with the same chemotherapy plus tumor treatment fields in patients with locally advanced pancreatic adenocarcinoma.
Five hundred and seventy-one eligible patients were enrolled in the study with a total of 405 (198 in the treatment field group and 207 in the standard arm) comprising the modified intent- to-treat population. The duration of chemotherapy treatment was comparable in both study arms, and patients receiving treatment fields had a median exposure of almost 27 weeks.
Statistically significant improvements were observed for several study endpoints, including overall survival (a median of 16.2 versus 14.2 months), distant PFS (at 13.9 versus 11.5 months) and pain-free survival (at 15.2 versus 9.1 months), all in favor of the treatment fields arm. Although quality of life data were not reported in detail, the authors noted a significant improvement in global health status in the treatment fields arm. Safety data showed a higher level of skin adverse events in the treatment fields arm but were otherwise as expected for the GnP combination.
These are quite remarkable results which add to the growing evidence base for tumor treatment fields and are particularly compelling in this patient group given the substantial improvement in pain-free survival. It will be especially interesting to see the mature analysis of the quality-of-life endpoints in a subsequent report.
The final selection today is Abstract 6001, which describes the C-POST trial, a phase 3 trial of adjuvant cemiplimab versus placebo in patients with high-risk cutaneous squamous cell carcinoma of the skin. This study was presented by Dr. Danny Rischin from the Peter MacCallum Cancer Centre in Melbourne, Australia.
Although surgical resection with or without adjuvant radiation is curative in 90% of patients with cutaneous squamous cell carcinoma, high-risk features, including nodal disease, skin and subcutaneous metastases, perineural invasion and bone involvement, predict for an inferior prognosis.
Cemiplimab, a PD-1 targeting antibody is standard therapy for patients with locally advanced or metastatic disease who are not candidates for curative surgical resection or radiation therapy, with an overall response rate of almost 50%.
The C-POST study evaluated the use of cemiplimab as adjuvant therapy following surgery and radiation in high-risk patients, compared with placebo. Treatment was administered at 3-week intervals for 12 weeks, and then 6-week intervals for a further 36 weeks, with a primary endpoint of disease-free survival.
Four hundred and fifteen patients were randomized in the study, 209 to cemiplimab and 206 to placebo. With median follow-up at 24 months, Dr. Rischin reported a highly significant improvement in disease-free survival for the cemiplimab arm, 49.4 months for placebo versus not reached for cemiplimab, with improvements also observed in the rates of locoregional recurrence and distant recurrence at 80% and 60% reductions, respectively. No new safety signals were observed.
This study is potentially practice-changing and provides strong evidence that cemiplimab should be considered the new standard of care in this clinical context.
Thanks for listening today and join me again tomorrow to hear more top takeaways from ASCO25. If you value the insights that you hear on the ASCO Daily News Podcast, please remember to rate, review, and subscribe wherever you get your podcasts.
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The purpose of this podcast is to educate and to inform. This is not a substitute for professional medical care and is not intended for use in the diagnosis or treatment of individual conditions. Guests on this podcast express their own opinions, experience, and conclusions. Guest statements on the podcast do not express the opinions of ASCO. The mention of any product, service, organization, activity, or therapy should not be construed as an ASCO endorsement.
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Dr. John Sweetenham:
No relationships to disclose