Abstract B56: A phase I trial of the combination of dasatinib and lapatinib
Authors: Erlichman Charles , Menefee Michael E. , Northfelt Donald W. , Qin Rui , Reid Joel M. , Lingle Wilma L. , Oursler Merry Jo , Reinholz Monica M. , Molina Julian R. , Borad Mitesh J. 
Published: June 2012

Abstract
Src transduces activated HER tyrosine kinase and phosphorylates HER to further increase its activity. Src also is involved in osteoclast differentiation. We hypothesized that combining a HER tyrosine kinase inhibitor with a Src inhibitor would result in increased therapeutic activity. To address this hypothesis we performed a phase I trial of D and L to: 1)determine the maximally tolerated dose (MTD) of D combined with L; 2)describe the toxicities associated with this combination; 3)assess the pharmacokinetic (PK) interaction of L and D; 4) assess the effect of the L and D combination on circulating tumor cells (CTC) and on osteoclast precursor activation; 5)study the association of toxicity and/or tumor response with PK, and/or pharmacodynamic parameters; and 6)describe the responses of this combination. Eligibility criteria included ≥ 18 years of age, incurable solid tumors not amenable to other therapies, ANC ≥ 1500/ L, PLT ≥ 100,000/ L, total bilirubin ≤ ULN, AST ≤ 3 × ULN or AST ≤5 × ULN if liver involvement, creatinine ≤ 1.5 × ULN, Hgb ≥ 9.0 g/dL, K+ and Mg++ WNL, life expectancy ≥ 12 weeks, ejection fraction &gt; 50%, ECOG PS 0–2, and able to swallow pills whole. In addition to standard phase I exclusion criteria patients could not have received erlotinib, sunitinib, sorafenib, gefitinib, imatinib ≤ 4 weeks prior to registration. Each agent was administered once daily on a 28 day schedule. At the MTD patients were treated with D day 1, and day 9–28 and L day 2–28 to assess PK interaction. Dose levels (mg) were #1 D 70, L 1000, #2 D 100, L 1000, #3 D 140, L 1000. 12 patients were entered on the dose escalation portion of the trial and 15 were entered at the MTD. 5 patients entered at the MTD are too early to be fully evaluable. Characteristics of evaluable patients were: median age, 63; 46% female; PS 0 (64%) 1 (27%), 1 (9%); ≥ 3 prior chemotherapies (59%). DLT was seen in 2 patients at # 3 (1 patient, grade 3 hypermagnesemia, 1, grade 3 rash) and 1 patient at # 2 (grade 3 dyspnea). The MTD was determined to be # 2. No grade 4 or 5 events have been observed in this study. 6 patients had stable disease in the dose escalation cohort. 1 (RCC) was stable disease for 6 cycles, 2 (colorectal) were stable for 5 cycles, 1 (esophagus) was stable for 3 cycles, and 2 (GIST & leiomyosarcoma) were stable for 2 cycles. Analysis of drug levels, CTCs and circulating osteoclast precursors is ongoing. There was a consistent increase in the percentage of CD11b (monocyte/macrophage/osteoclast lineage marker) positive cells in circulation as treatment progressed. However, the late osteoclast lineage marker c-Fms was not similarly increased, suggesting that the elevated CD11b reflects an inflammatory response and not activation of osteoclastogenesis. D and L is a tolerable combination at nearly full doses of each drug. Funded by a grant from Glaxo Smith Kline and Bristol Myers Squibb.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B56.