The early data come from 10 patients with HPV-negative head and neck cancer and 17 patients with a type of colorectal cancer for whom immunotherapies don’t work well. The combination treatment shrank tumors in five patients with head and neck cancer (50%), eliminating the tumors in two of those patients, Moderna said in a statement. Another four patients in that group had stable disease, meaning their tumors had stopped growing.

The median duration of response had not been reached, meaning more than half of the patients with head and neck cancer are still responding to the treatment. However, no patients in the colorectal cancer group responded to the treatment.

Moderna presented the interim results virtually at the annual meeting of the Society for Immunotherapy of Cancer on Wednesday.

The combination staved off cancer progression in the head and neck patients for nearly 10 months. It’s tricky to make comparisons to Keytruda outside of a head-to-head trial, but Moderna figures the combo’s performance in this small group of patients stacks up “favorably” against published data for Keytruda. The company compared the 50% response rate and 9.8-month progression-free survival figures to 14.6% and two months, respectively, for Keytruda alone.

Moderna is recruiting more patients with head and neck cancer for this study, and, based on these early data, it is increasing the number of patients it wants to enroll.

[huge_it_slider id=”15″]The data come a month after Merck returned the rights to a respiratory syncytial virus (RSV) vaccine for adults to Moderna. The Big Pharma had helped Moderna advance the prospect into the clinic but quit the collaboration to focus on its in-house RSV efforts. The duo remain partners in oncology, though, having teamed up in 2016 on personalized cancer vaccines and adding a vaccine for KRAS-mutated cancers in 2018.

The personalized vaccine program, mRNA-4157, is based on neoantigens found in individual patients’ tumors. The company then builds custom strands of mRNA containing instructions for the body to make those neoantigens and trigger the immune system to attack them. Moderna is also testing it in a phase 2 melanoma study in combination with Keytruda versus Keytruda alone.

And the KRAS candidate, mRNA-5671, is in a phase 1 trial assessing its safety alone and in tandem with Keytruda. This study will involve patients with various KRAS-mutated cancers, including non-small cell lung, colorectal and pancreatic cancers.