Phase I Trial of Bortezomib (PS-341; NSC 681239) and Alvocidib (Flavopiridol; NSC 649890) in Patients with Recurrent or Refractory Indolent B-Cell Neoplasms - Update of the “Bolus” Infusion Schedule of Alvocidib.

Abstract 2959

Preclinical studies suggest that neoplastic cells may be particularly sensitive to simultaneous interruption of cell cycle and survival signaling pathways. We have previously reported that the cyclin-dependent kinase inhibitor alvocidib interacts with bortezomib, a proteasome inhibitor, to induce mitochondrial injury and apoptosis in human leukemia, myeloma, and lymphoma cells (Dai et al, Oncogene 22:7108, 2003; Dai et al, Blood 104:509, 2004). These actions were associated with inhibition of NF-κB DNA binding, increased expression of pJNK, and down-regulation of XIAP and Mcl-1. Based on these findings, a phase I trial was initiated in which bortezomib was administered in conjunction with alvocidib on the same days, according to 2 separate schedules: a “hybrid” infusion schedule (half the dose over 30 minutes and half over a 4-hour infusion); and a bolus infusion schedule in which alvocidib was administered over 1 hour. Results of the hybrid infusion schedule have recently been reported (Holkova et al, Clin Cancer Res 17:3388, 2011). The primary objective was to identify the maximum tolerated doses (MTDs) for the combination in the treatment of recurrent or refractory indolent B-cell neoplasms.

Eligible patients included those with multiple myeloma (MM) or non-Hodgkin's lymphoma (NHL), with recurrent or refractory disease following at least 1 prior systemic therapy. To date, 43 patients have been treated at 9 dose levels. Patients with the following disease types have been treated: MM n=25 (Waldenstrom's macroglobulinemia n=2), NHL n=18 (mantle cell lymphoma n=5). The male:female ratio was n = 31 (72%):12 (28%); the median age was 65 (range: 40–79) years; ECOG performance scores ranged from 0–1; and the median number of prior therapies was 3 (range: 1–10). The schedule of administration was bortezomib via intravenous push over 3–5 seconds followed by alvocidib via intravenous 1-hour infusion on days 1, 4, 8, and 11; on a 21-day cycle, with indefinite continuation for responding patients and those with stable disease.

Adverse events (AEs) were evaluated using CTCAE version 4. Dose limiting toxicities (DLTs) observed to date are shown in Table 1. Grade 3 and 4 AEs possibly, probably, or definitely related to study treatment tht occurred in ≥ 5% of patients were dehydration (7%), diarrhea (19%), fatigue (16%), febrile neutropenia (5%), leukopenia (37%), lymphopenia (28%), neutropenia (58%), peripheral neuropathy (12%), and thrombocytopenia (44%). No grade 5 events were observed. One patient developed tumor lysis syndrome and required hospitalization for 48 hours with complete recovery. Common grade 2 AEs possibly, probably or definitely related to treatment were anemia (30%), anorexia (28%), diarrhea (47%), fatigue (60%), leukopenia (47%), lymphopenia (28%), and thrombocytopenia (56%).

Of the 43 patients treated, 38 have been evaluable for response. Patient responses are shown in Table 2. Correlative studies examining expression of pJNK, Mcl-1, XIAP, PARP, and NFκB are being collected for processing at the end of the study.

Collectively, these findings indicate that the combination of bortezomib and alvocidib, the latter administered as a 1-hour infusion, is tolerable. The regimen appears active in patients with relapsed and/or refractory MM or NHL, justifying phase II studies to determine the activity of this regimen more definitively. The MTD has not yet been reached.