MedPacto unveils topline data of vactosertib-Keytruda combo p1b/2a trials

MedPacto currently conducts the early-phase clinical trials of combination therapy of its new drug candidate, vactosertib, and immune checkpoint inhibitor Keytruda (pembrolizumab). But it has been confirmed that the occurrence rate of adverse events (AE) of third class or higher related to stomach cancer treatment reached 66.7 percent.

MedPacto, a new drug discovery and development company, received the combo therapy’s phase 1b/2a clinical trials data from a contract research organization on Tuesday.

The company won approval for the study from the Ministry of Food and Drug Safety in September 2018.

It has since evaluated the vactosertib-pembrolizumab combo therapy’s safety, drug resistance, pharmacokinetics, and anti-tumor activity in patients with metastatic or locally progressive colorectal cancer or gastric/gastric esophageal adenocarcinoma.

According to MedPacto, the median value of overall survival (mOS) in the colon cancer group was 15.8 months – 17.35 months in the group administered with vactosertib 300mg twice a day and 9.89 months in the group injected with 200mg twice daily.

The overall response rate (OSS) of colon cancer patients was 13.6 percent --18.2 percent in the 300mg group and 10.5 percent in the 200mg group.

Among colon cancer patients, the median value of progression-free survival (mPFS) was 1.28 months in all groups -- 1.22 months in the group administered with 200mg three times a day or 300mg two times a day 1.31 months in the group injected with 200 mg twice daily.

The mOS were 4,63 months among gastric cancer patients, and mPFS was 1.20 months.

As a result of the interim safety analysis, there were no adverse events causing death in colon and stomach cancer patients.

Among the most frequently reported AE from colon patients were rash, with 19 patients (32.2 percent, 34 cases), decreased appetite with 18 patients (30.5 percent, 27 cases), pruritus with 17 patients (28.8 percent, 32 cases), and headache with17 patients (28.8 percent, 20 cases).

In the colon cancer group, the number of AEs with three degrees or higher in the 200mg-twice daily, 200mg-thrice daily, and 300mg-twice daily groups were nine patients (47.4 percent, 33 cases), four patients (57.1 percent, nine cases), and 13 patients (39.4 percent, 27 cases).

In the stomach cancer group (safety population), eight patients (66.7 percent, 14 cases) reported treatment-related adverse events. Most common were anemia with five patients (41.7 percent, eight cases), hypoalbuminemia with four patients (33.3 percent, four cases), abdominal pain with three patients (25.0 percent, five cases), abdominal extension with three patients (25.0 percent, three cases), and decreased appetite with three patients (25.0 percent, three cases).

The topline data was an interim analysis. MedPacto has changed the number of subjects by adding 30 to the 200mg-once daily group and 19 to the 200mg-twice daily group and is conducting trials. Afterward, it plans to receive final topline data, including that of additional patients.

The company said the final analysis after the clinical trial could produce different results from the interim analysis.

“We will secure additional data on the efficacy, safety, and drug resistance of the vactosertib-pembrolizumab combination therapy and decide the optimal dose for the follow-up clinical process,” MedPacto said.

The company added that it would also have in-depth discussions with MSD according to their contract signed in December 2021 and submit the investigational new drug (IND) plan for follow-up clinical trials to the U.S. FDA.

"We will also receive pembrolizumab support from MSD for use in the upcoming clinical trials,” the company added.