AbbVie lung cancer drug shows promise, but has high expectations to meet
- An investigational drug from AbbVie showed some promise in treating patients with small-cell lung cancer (SCLC), a particularly deadly form of cancer, the company said Sunday at the annual meeting of the American Society for Clinical Oncology.
- Treatment with the drug, known as Rova-T, helped halt cancer growth in 68% of patients evaluated in a Phase 1a/1b clinical trial, according to a statement from the Memorial Sloan Kettering Cancer Center. Among those patients, 18% saw their tumors shrink.
- While the results were promising in a therapeutic space with limited treatment options, Rova-T has high expectations to meet. In April, AbbVie paid $5.8 billion to acquire Stemcentrx, which has developed Rova-T (and other cancer candidates) up until now. The deal has the potential to be worth another $4 billion if all milestones are hit.
Development of Rova-T is part of AbbVie's effort to build a foundation in treatment of solid tumors, after carving out a space in hematological malignancies with Imbruvica and the recent approval of its leukemia drug Venclexta.
Rova-T is an antibody drug conjugate, a powerful combination of a targeted antibody with a cytotoxic warhead. The drug looks for a specific protein - a delta-like protein 3 (DLL3) - commonly expressed in more than 80% of SCLC patient tumors, but not on healthy adult cells.
Gary Gordon, vice president of oncology development at AbbVie, called DLL3 a "signpost" on the surface of tumor cells which Rova-T recognizes. When Rova-T binds to DLL3, it gets pulled into the cancer cell, which the toxin subsequently kills.
Expression of DLL3 in patient tumors, then, is a key biomarker for Rova-T. Among patients in the study whose tumors overexpressed DLL3, stable disease was seen in 89% of patients. Ten of the 26 patients in this subgroup (39%) had their tumors shrink.
Treatment with Rova-T did lead to some serious side effects, including low platelet counts, pleural effusions, and skin rashes.
But Gordon believes the study results have given researchers a good understanding of how to balance the drug's side effects with its benefit. "The dose has been brought down to where platelet counts are easy to manage," Gordon said, addressing the thrombocytopenia concerns.
AbbVie expects to get more data on Rova-T next year from a readout of a pivotal Phase 2 study. The 154-patient trial is currently under way and looks only at patients who express DLL3. If all goes well, AbbVie hopes to launch the drug in 2018 through accelerated approval for third-line treatment of SCLC.
The Chicago-based company will need Rova-T, along with a number of other "near-term growth assets," to perform well if it hopes to offset the generic threat to its top-selling anti-inflammatory drug Humira.
Growth in oncology will be a big part of those plans, as evidenced not only by AbbVie's bet on Stemcentrx and Rova-T, but also its $21 billion dollar deal last year to acquire Pharmacyclics.
"The science that Stemcentrx brings augments our solid tumor platform but will also help in hematological malignancies. We are building engines that give us the ability to identify new targets and give us the toolbox to address those targets," Gordon said.
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