The use of post-surgical (adjuvant) Libtayo (cemiplimab)in patients with resectable stage 2-4 cutaneous squamous cell carcinoma (CSCC) showed a survival benefit after a year and a half of follow up, leading to a wider phase 3 study, according to data presented at the ESMO 2023 Congress.
Data included one-year follow up of a single-arm, multicenter phase 2 study that looked at the use of Libtayo therapy after surgery. A year ago, researchers published data for 79 patients given neoadjuvant (presurgical) Libtayo prior to surgery, which showed the first part of the study met its primary endpoint with 40 patients achieving a pathological complete response (pCR; no residual invasive disease in the breast and lymph nodes) and 10 patients who achieved a major pathological response (MPR; less than or equal to 10% residual viable tumor).
Now, researchers found that after a year and a half of follow up after surgery and adjuvant therapy, all 40 patients who achieved a pCR did not have disease recurrence, while just one patient who had an MPR recurred.
“It’s important to note that in the adjuvant portion of the trial, it was left to investigator discretion whether patients would receive adjuvant Libtayo up to 48 weeks, adjuvant radiation, or observation, and this was based on local pathology review,” explained Dr. Neil D. Gross, professor, and director of clinical research in the department of head and neck surgery at The University of Texas MD Anderson Cancer Center in Houston, who presented these data at the meeting in Madrid, Spain.
Among the patients who initially achieved a pCR, only one patient was given adjuvant radiation therapy. And this group of patients had an estimated 12-month event free survival (EFS, the measure of time after treatment that a group of people in a clinical trial has not had cancer come back or get worse) rate of 94.9%
compared with 72.0% in the 22 patients who did not have surgery or were non-responders. Further, the 12-month EFS rate was also superior in the MPR (10 patients) and pathological partial response (pPR; seven patients) groups compared with those who didn’t respond at 89% and 100%, respectively.
Among all patients given neoadjuvant Libtayo, the median EFS was not reached, but the estimated 12-month EFS rate was 89%. Median EFS was also not reached in the pCR, MPR and pPR groups who had adjuvant therapy compared with a median EFS of 25 months in the non-responder group.
These data were also published concurrently in The Lancet Oncology, where a post-hoc sensitivity analysis was done for 74 patients with stage 3-4 disease. In this group, their 12-month estimated EFS rate was 88% and 87% at 24 months.
At a median follow-up of 18.7 months (range, 1.3-30.4 months), researchers also found a 12-month overall survival (OS) rate of 92%, but median OS was not reached. Further, among the 70 patients that underwent surgery, six patients (9%) had disease-free survival.
“What is shown here is the stark contrast between patients who had any pathologic response and those who either did not have surgery or did not have a pathologic response in favor of the responders,” explained Gross.
Of the 79 patients enrolled, 70 had surgery with 65 patients having post-surgical management data. Overall, 49% were observed after surgery, 25% were given adjuvant Libtayo and 26% had adjuvant radiotherapy. Researchers conducting part 1 of this study administered Libtayo at 350 mg every three weeks for four doses before patients underwent surgery. At the time, an objective response was seen in 68%. In this first part of the study, 87% of patients had a side effectof any grade that occurred during the study with 18% of patients experiencing grade 3 or higher side effect.
Now, among all patients, 89% had a treatment-emergent side effect of any grade and 19% had a grade 3 or greater treatment-emergent side effect. One death was attributed to study treatment for a 93-year-old patient with congestive heart failure exacerbation, which was previously reported. In the adjuvant Libtayo group, no new safety signals were observed with a treatment-emergent side effects of any grade experienced by 10% or more of patients seen in 13 patients and four patients had a grade 3 or greater a treatment-emergent side effect. The most common a treatment-emergent side effect of any grade were diarrhea
(25%), fatigue (25%), increased blood creatinine (25%) and squamous cell carcinoma of the skin (25%).
The four grade 3 or greater a treatment-emergent side effects included one patient with cardiomyopathy, one patient with hypophysitis, one patient that underwent a limb amputation and one patient with increased blood potassium. The cases of grade 3 worsening cardiomyopathy and hypophysitis were considered serious a treatment-emergent side effects; however, no deaths were related to Libtayo.
“These data support the development of a randomized phase 3 trial, which is underway and set to begin enrollment in 2024,” concluded Gross.
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