Purpose: A vitamin B12 supplement is required in pemetrexed single agent therapy. Intramuscular administration is the method of choice; however, oral administration is simpler and easier and may be sufficiently effective. We conducted a Phase II study to evaluate the safety of oral administration of vitamin B12 in patients with advanced non-small cell lung cancer who received pemetrexed single agent therapy.
Methods: Folic acid and vitamin B12 were given orally for ˃ 1 week before pemetrexed administration. The primary end-point was onset of a grade ≥ 3 neutropenia ratio (50% of threshold expression ratios; an expectation expression ratio of 21%; α, 0.05; β, 0.1). Blood concentration of folic acid and homocysteine which are markers of vitamin B12 deficiency were also examined (UMIN000003180).
Results: A total of 25 cases were registered from February 2010 to July 2014. The ratio of grade ≥ 3 neutropenia was 36% (95% CI 22-52 %). Grade ≥ 3 non-hematologic toxicity and hematologic toxicity were seen in 20% (5 cases) and 44% (11 cases) of patients, respectively. In addition, the homocysteine blood concentration just before the first cycle dosage of pemetrexed was significantly elevated relative to the 2-3 cycle.
Conclusion: This study failed to meet its primary endpoint. We could not demonstrate the safety and efficacy of the 1-week vitamin B12 oral administration protocol as compared with intramuscular administration.
Keywords: Folic acid; Lung cancer; Pemetrexed; Vitamin.