A phase II study of the oral VEGF receptor tyrosine kinase inhibitor vatalanib (PTK787/ZK222584) in myelodysplastic syndrome: Cancer and Leukemia Group B study 10105 (Alliance)

BACKGROUND

Angiogenesis is implicated in the pathophysiology and progression of myelodysplastic syndromes (MDS). Vatalanib (PTK787/ZK222584; Novartis and Schering AG) inhibits receptor tyrosine kinases of vascular endothelial growth factor, platelet derived growth factor and c-Kit. We examined whether vatalanib induces hematological responses in MDS and/or delays progression to acute myeloid leukemia (AML) or death.

METHODS

Two cohorts were studied. Vatalanib 1250 mg orally was given once daily (cohort 1) or 750-1250 mg once daily in an intra-patient dose escalating schedule (cohort 2) in 28-day cycles to 155 patients with MDS; 142 patients were evaluable for response and 153 for toxicity.

RESULTS

The median age was 70.5 years; 51 % had low risk (International Prognostic Scoring System {IPSS} Low/Intermediate-1) and 32 % had high risk (IPSS Intermediate-2/High) MDS. Hematological improvement was achieved in 7/142 (5 %) patients; all 7 were among the 47 patients able to remain on vatalanib for at least 3 months (hematological improvement achieved in 15 % of these 47 patients). For patients with low risk and high risk MDS, respectively, median progression-free survivals were 15 and 6 months, median times to transformation to AML were 28 and 6 months, and median overall survivals were 36 and 10 months. The most frequent non-hematological adverse events grade ≥ 2 were fatigue, nausea or vomiting, dizziness, anorexia, ataxia, diarrhea, and pain. Two deaths (one intra-cerebral hemorrhage and one sudden death) were possibly related to vatalanib.

CONCLUSIONS

Vatalanib induces improvement in blood counts in a small proportion of MDS patients. Clinical applicability is limited by side effects.

Vatalanib: the clinical development of a tyrosine kinase inhibitor of angiogenesis in solid tumours

The licensing of bevacizumab in patients with metastatic colorectal cancer has fueled research in angiogenesis. Vatalanib (PTK787/ZK 222584), a potent oral tyrosine kinase inhibitor with a selective range of molecular targets, has been extensively investigated and has shown promising results in patients with colorectal cancer in early trials. Dynamic contrast-enhanced MRI has been useful as a pharmacodynamic tool to define the dose that has a biological effect. The primary objectives of the Phase III CONFIRM (Colorectal Oral Novel Therapy for the Inhibition of Angiogenesis and Retarding of Metastases in First-line) studies were not met. However, an interesting pre-planned subset analysis in both studies showed that patients with high lactate dehydrogenase derived clinical benefit. Although this type of analysis should always be considered with caution, the Phase III clinical programme of vatalanib is continuing with further innovative studies looking at other indications and schedules for vatalanib.