Hope I spelled that one right. This is another new agent targeting the HER family:
[37] Neratinib (HKI-272), an irreversible pan erbB receptor tyrosine kinase inhibitor: phase 2 results in patients with advanced HER2+ breast cancer.
Burstein HJ, Sun Y, Tan AR, Dirix L, Vermette JJ, Powell C, Zacharchuk C, Badwe RA Dana Farber Cancer Institute, Boston, MA; Cancer Institute and Hospital, Chinese Acadeny of Medical Sciences, China; Cancer Institute of New Jersey, New Brunswick, NJ; Oncology Center AZ St-Augustinus, Antwerp, Belgium; Wyeth Research, Cambridge, MA; Tata Memorial Hospital, Mumbai, India
Background: Neratinib (HKI-272) irreversibly inhibits the tyrosine kinase receptors, erbB1 (EGFR) and erbB2 (HER2). In a phase 1 study, neratinib was tolerable and demonstrated antitumor activity in patients (pts) with solid tumors, including 8 of 25 evaluable pts with erbB2-positive advanced breast cancer. In this open-label, 2-arm phase 2 study, pts with stage IIIB, IIIC or IV erbB2-positive advanced breast cancer were evaluated to further characterize the safety and efficacy of neratinib.
Methods: ErbB2 gene amplification in tumor tissue, by FISH was a requirement for study entry. Pts were assigned to arm A if they had prior treatment with trastuzumab and to arm B if they had no prior treatment with trastuzumab or other erbB2-targeted drug. All pts received oral doses of 240 mg of neratinib daily. The primary endpoint was progression-free (PFS) survival rate at 16 weeks (wks).
Results: Enrollment of 136 pts (arm A: 66 pts; arm B: 70 pts; median age 50 years [range 31-83 years]) was completed in November 2007. Common neratinib-related adverse events (AEs), any grade, were diarrhea (89%), nausea (29%), vomiting (23%), fatigue (16%), and anorexia (15%). Diarrhea was the only
grade 3 AE that occurred in
5% of pts, 26/136 (19%) total pts, 27% in arm A and 11% in arm B. Dose reductions occurred in 27% total pts, 36% in arm A and 19% in arm B, most commonly because of diarrhea. The main reasons for discontinuation of the study were disease progression (arm A: 74%, arm B: 43%), and AEs (arm A: 8%, arm B: 4%).
124 pts (arm A: 61 pts, arm B: 63 pts) were evaluable for efficacy based on independent assessment and 131 pts (arm A: 65 pts, arm B: 66 pts) were evaluable based on investigator assessment. The objective response rates (complete or partial response) were 26% (95% CI 16%, 39%) in arm A, 51% (95% CI: 38%, 64%) in arm B for independent assessment and 34% (95% CI: 23%, 47%) in arm A, 62% (95% CI: 49%, 74%) in arm B for investigator assessment. The 16-wk PFS rates were 61% in arm A, 75% in arm B (independent); 57% in arm A, and 78% in arm B (investigator). The median PFS for independent [and investigator assessment] was 23 [22] wks in arm A and 40 [35] wks in arm B.
Discussion: Neratinib demonstrates robust antitumor activity in pts with erbB2-positive advanced breast cancer, with objective response rates of 26% in pts who had prior treatment with trastuzumab and 51% in pts who had no prior treatment with trastuzumab. Additional updated efficacy and safety data will be presented.
The main adverse side effect of this drug is diarreah (I still can't spell that word -maybe I just don't want to think about it!). Such that it would replace tykerb as the diva drug of rest area stops. It worked really really well against the cancer but as Dr. Slamon pointedly asked, would it really be appropriate for a patient who was a schoolteacher! Despite the nearly 100% reporting of this side effect, there were almost no discontinuations due to this, so apparently the problem decreased over time or people were able to manage it. There will be more to come on this one for sure...