Shares in AbbVie fell nearly as much as 12 percent Thursday after the company said it will not seek accelerated FDA approval for the antibody-drug conjugate rovalpituzumab tesirine, also known as Rova-T, in third-line relapsed/refractory small-cell lung cancer (SCLC) based on results from the Phase II TRINITY trial. AbbVie explained that its decision came after discussions with the agency regarding the "magnitude of effect across multiple parameters" in the single-arm study. 

The trial investigated Rova-T in 177 DLL3-expressing SCLC patients with relapsed/refractory disease after receiving at least two previous regimens, including at least one platinum-based regimen. The primary study objective was examining the efficacy of the drug as a third-line or later treatment, while secondary endpoints included RECIST-assessed progression-free survival, duration of response and clinical benefit rate, as well as safety and tolerability. 

Results showed that the objective response rate was 16 percent, with the average duration of response being 4.1 months, while median overall survival was 5.6 months. Additionally, the probability of patients being alive after 12 months was 17.5 percent. 

Leerink Partners analyst Geoffrey Porges estimated recently that the "hurdle rate for commercial viability" for Rova-T was an overall response rate of 30 percent and a median overall survival rate of over 5 months. Meanwhile, Jefferies analyst Ian Hilliker noted that the TRINITY results were lower than the respective overall response and median overall survival rates of 39 percent and 5.8 months seen with Rova-T during Phase I testing. The drug also failed to set itself apart from standard chemotherapy or emerging immunotherapies, with Hilliker suggesting the TRINITY data "have fallen short of what would be required by the FDA for accelerated approval."

AbbVie's chief scientific officer Mike Severino said "although the results from the study were not what we hoped for, we look forward to receiving data from the ongoing Phase III [MERU and TAHOE] studies in the first- and second-line settings." Severino added that AbbVie continues to believe that "Rova-T has potential for patients with [SCLC] and other DLL3-expressing cancers." 

AbbVie obtained rights to Rova-T as part of its $5.8-billion takeover of Stemcentrx in 2016. AbbVie has also signed a deal with Bristol-Myers Squibb to study Rova-T in combination with Opdivo (nivolumab), both alone and together with Yervoy (ipilimumab), in the treatment of relapsed extensive-stage SCLC. 

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