Merck (NYSE:MRK) and Daiichi Sankyo (OTCPK:DSNKY) (OTCPK:DSKYF) on Saturday announced interim results from a Phase 2 trial for lung cancer patients treated with ifinatamab deruxtecan (I-DXd), which belongs to a novel cancer drug class called antibody-drug conjugates (ADC).

Citing an Apr. 25 data cut, the duo said I-DXd at 12 mg/kg dose and 8 mg/kg dose acted against small cell lung cancer, leading to confirmed objective response rates (ORR) of ~55% and ~26%, respectively.

Detailed results from the trial named IDeate-Lung01 indicated that the 12 mg/kg dose was linked to 23 partial responses, while the 8 mg/kg dose was linked to one complete response and 11 partial responses.

With a median follow-up of 15.3 months and 14.6 months for the two-dose group, the median overall survival reached 11.8 months and 9.4 months for the 12 mg/kg and 8 mg/kg doses, respectively.

The companies also announced preliminary responses in patients with brain lesions, noting that their intracranial ORRs have reached 50.0% and 66.7% across the two dose groups.

As for safety, 17% of patients in the 12 mg/kg dose and 6.5% in the 8 mg/kg dropped out of the trial due to adverse events.

The two-part global study involved patients with extensive-stage small-cell lung cancer who had undergone a median of two prior lines of therapy, including more than 75% who had received immunotherapy.

Merck (MRK) and Daiichi (OTCPK:DSNKY) have selected the 12 mg/kg dose for the dose expansion part of the trial. The data set is scheduled for an oral presentation on Sunday at the World Conference on Lung Cancer in San Diego, California.