Activity NotedThree of the 13 patients with SCLC enrolled had chemotherapy-naïve disease. Two of these three patients had an objective response (partial response or PR) by RECIST criteria to treatment with IMGN901 plus E/C. All of the 10 patients with previously treated SCLC had received prior platinum-based therapy, and seven of these patients had platinum-resistant/refractory disease. Four of these ten patients had a PR, including two of the patients with platinum-resistant/refractory disease. Among all of the 33 patients enrolled, ten had an objective response, and 24 (72.7%) had disease control (objective response or stable disease). ImmunoGen’s NORTH Trial The 120-patient NORTH trial is designed to evaluate the efficacy and safety of IMGN901 for first-line treatment of extensive disease SCLC. All patients enrolled are provided with up to six cycles of C/E. Two-thirds of the patients enrolled are randomized to also receive IMGN901. These patients can elect to remain on IMGN901, as monotherapy, after completion of the C/E cycles if benefiting from treatment. The trial is designed to compare the findings in the IMGN901-including treatment arm to historic controls, with the control arm serving to verify consistency with historical results. The NORTH trial utilizes a Simon Two-Stage Design: once 59 patients have been enrolled across the two study arms, those two cohorts of patients will be followed for an interim analysis of progression-free survival (PFS) at 6 months. The interim analysis will focus on whether the IMGN901-including treatment arm met pre-defined clinical benefit hurdles. Success on this interim analysis will serve as a basis for certain development decisions by the Company. The primary endpoint of the NORTH trial is PFS. Secondary endpoints include PFS at 6 months, overall survival at 12 months, time to progression, overall survival, and overall response rate. About IMGN901 IMGN901 is designed to target and kill CD56+ cancer cells. This TAP compound is wholly owned by ImmunoGen and consists of the Company’s CD56-targeting antibody with its DM1 cancer-cell killing agent attached using one of its engineered linkers. IMGN901 has been granted orphan drug designation for SCLC in the US and Europe.