Researchers have found that concurrent treatment with gemcitabine as well as cisplatin and intensity-modulated radiation therapy may effectively increase the pathologic complete response rates in patients with locally advanced squamous cell carcinoma of the vulva, according to findings presented by Horowitz et al during the Plenary Session of the Society of Gynecologic Oncology (SGO) 2023 Annual Meeting on Women’s Cancer.
“[Patients] with locally advanced vulvar cancer are currently treated with standard chemoradiation, which results in a high number of patients experiencing locoregional recurrence in their lifetime. [The new study] was designed to determine whether the addition of gemcitabine to cisplatin and higher doses of radiation administered with [intensity-modulated radiation therapy] could improve the efficacy of the treatment while avoiding added toxicity for these patients,” explained lead study author Neil S. Horowitz, MD, Associate Professor of Obstetrics, Gynecology, and Reproductive Biology at Harvard Medical School and Director of Clinical Research in Gynecologic Oncology at the Dana-Farber Brigham Cancer Center at Milford Regional Medical Center.
Study Methods and Results
In the new NRG Oncology phase II NRG-GOG-0279 clinical trial (ClinicalTrials.gov identifier: NCT01595061), the researchers analyzed the cases of 52 patients with locally advanced vulvar cancer that was not amendable to surgery. The patients who had positive nodes were assigned to receive 64 Gy to the vulva and those who had unresectable nodes wre assigned to receive 50 Gy or 64 Gy to the groin and low pelvis. The researchers also administered 40 mg/m2 of cisplatin and 50 mg/m2 of gemcitabine weekly throughout the intensity-modulated radiation therapy—and assessed treatment response after 6 to 8 weeks of follow-up.
The patients involved in the study received a median of six cycles of gemcitabine and cisplatin. Among the 44 patients who had their radiation therapy compliance reviewed, 75% of them (n = 33) had high quality intensity-modulated radiation therapy and 25% (n = 11) had minor deviations. Further, among all of the study participants, 73.1% of them (n = 38) achieved pathologic complete responses (90% confidence interval [CI] = 61.2%–83.0%) and 71.2% of them (n = 37) had complete clinical responses (90% CI = 59.1%–81.3%). At the median follow-up of 51 months, progression-free survival at 12 months was 74% (90% CI = 62.2%–82.7%) and overall survival at 24 months was 69.6% (90% CI = 57.4%–79%). The researchers also reported that 1 patient experienced a grade 5 toxicity, 25 patients experienced grade 3 adverse events, and 18 patients experienced grade 4 adverse events. Common grade 3 and 4 adverse events included radiation dermatitis, leukopenia, thrombocytopenia, and electrolyte abnormalities.
As the primary endpoint, the researchers hoped to improve pathologic complete response rates by 20% or more when compared with the rate of 50% reported for the GOG-0205 trial. If successful, the researchers noted that the treatment would warrant further investigation. The trial also evaluated complete clinical responses, progression-free survival, overall survival, and adverse events as secondary endpoints.
“While this approach improved survival and response outcomes for [these patients], it is important to note that future research is needed to find the ideal treatment regimen for this patient population to [further] improve clinical outcomes while minimizing toxicity,” Dr. Horowitz concluded.
Disclosure: The research in this study was supported by grants from the National Cancer Institute.
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