Safety of Same-Day Vitamin B12 Supplementation in Patients Receiving Pemetrexed for the Treatment of Non-Small-Cell Lung Cancer or Pleural Mesothelioma: A Retrospective Analysis

Mechanisms, Management and Prevention of Pemetrexed-Related Toxicity

Pemetrexed is a cytostatic antifolate drug and a cornerstone in the treatment of lung cancer. Although generally well tolerated, a substantial part of the patient population experiences dose-limiting or even treatment-limiting toxicities. These include mucositis, skin problems, fatigue, renal toxicity, and neutropenia. Several studies confirmed that pemetrexed pharmacokinetics can serve as a prognostic factor for the development of toxicity, especially for neutropenia. Preventing and managing toxicity of pemetrexed can help to ensure durable treatment. Several evidence-based strategies are already implemented in clinical care. With the introduction of standard vitamin supplementation and dexamethasone, the incidence of hematological toxicity and skin reactions substantially decreased. In the case of high risk for toxicity, granulocyte colony-stimulating factor can be used to prevent severe hematological toxicity. Moreover, high-dose folinic acid can resolve severe pemetrexed-induced toxicity. There are several experimental options to prevent or manage pemetrexed-related toxicity, such as the use of standard folinic acid, hemodialysis, antidotes such as thymidine, hypoxanthine, and glucarpidase, and the use of therapeutic drug monitoring. These strategies still need clinical evaluation before implementation, but could enable treatment with pemetrexed for patients who are at risk for toxicity, such as in renal impairment.

A prospective observational study of on-treatment plasma homocysteine levels as a biomarker of toxicity, depression and vitamin supplementation lead-in time pre pemetrexed, in patients with non-small cell lung cancer and malignant mesothelioma

OBJECTIVES

Vitamin supplementation reduces pemetrexed toxicity. Raised plasma homocysteine reflects deficiency in vitamin B12 and folate, and is suppressed by supplementation. This observational study of 112 patients receiving pemetrexed-based chemotherapy assessed homocysteine levels after 3 weeks of vitamin supplementation, hypothesising high levels would correlate with ongoing deficiency, thus increased toxicity.

MATERIAL AND METHODS

Primary endpoint was the composite of proportion of patients with treatment delay/ dose reduction/ drug change or hospitalisation during the first six weeks of chemotherapy, comparing those with normal plasma homocysteine (successfully supplemented, SS) and those with high homocysteine (unsuccessfully supplemented, USS). Secondary endpoints included toxicity and analyses for depression. Post-hoc analysis examined correlation between interval of vitamin and folate supplementation and pemetrexed on primary endpoint and grade 3-4 toxicities.

RESULTS

Eighty-four patients (84%) were successfully supplemented (SS group). The proportion of patients undergoing a treatment delay/ dose reduction/ drug change or hospitalisation in SS group was 44.0% (95% confidence interval [CI] 33.2%-55.3%) and in USS group was 18.8% (95% CI 4.0%-45.6%) (p = 0.09). Twelve percent of patients gave a past history of depression however 66% of patients had an on study Hospital Anxiety and Depression (HAD) score of >7. Supplementation status was not associated with depression. The median overall survival (OS) was 11.8 months (95% CI 8.6-16.5) in the SS group and 8.8 months (95% CI 6.6-16.2) in the US group (p = 0.5). The number of days (<7 or ≥ 7 days) between vitamin B12 and folate initiation and pemetrexed administration, had no effect on the primary endpoint and grade 3-4 toxicities.

CONCLUSION

On-treatment homocysteine levels were not a biomarker of toxicity or depression. Standard vitamin supplementation is adequate in the majority of patients receiving pemetrexed. High HAD score were noted in this population giving an opportunity for mental health intervention. The lead-in time for vitamin supplementation can be short.

Serum Homocysteine and Vitamin B12 as Biomarkers for Haematological Toxicity in Lung Adenocarcinoma Treated With Pemetrexed

Background Serum homocysteine (Hcy) and vitamin B12 (VitB12) were investigated as serological markers for the prediction of pemetrexed induced haematological toxicity in patients with adenocarcinoma of the lung.

Material and Methods A total of 35 lung adenocarcinoma patients who received pemetrexed chemotherapy as first-line treatment were included in the present study. The patients received pemetrexed 500 mg/m2 once every three weeks until disease progression. Serum Hcy and VitB12 levels were analysed prior to chemotherapy. Haematological toxicities (leucopenia, neutropenia and thrombocytopenia) were graded for each cycle of chemotherapy. Serum Hcy and VitB12 concentrations were compared between grades 0-1 and 2-4 haematological toxicity groups.

Results A total of 151 chemotherapy cycles were administered to 35 lung adenocarcinoma patients. However, the serum Hcy and VitB12 concentration were only examined and recorded in 61 out of the 151 chemotherapy cycles. For the 61 cycles, grade 2-4 leucopenia, neutropenia and thrombocytopenia were observed in 21, 20 and 10 cases, respectively. Serum Hcy levels were 14.91±4.67 μg/ml, 15.50±4.35 μg/ml and 16.04±4.90 μg/ml for grade 2-4 leucopenia, neutropenia and thrombocytopenia, respectively, which were significantly higher than those of grade 0-1 groups (p<0.05). However, serum VitB12 were not statistically different between grade 0-1 and 2-4 haematological toxicity groups (p>0.05). The area under the ROC curve (AUC) were 0.73 (0.58-0.88), 0.80 (0.66-0.94), 0.75 (0.57-0.93) for serum Hcy and 0.65 (0.50-0.79), 0.64 (0.49-0.78), 0.68 (0.49-0.87) for serum VitB12 as predictive biomarkers of grade 2-4 leucopenia, neutropenia and thrombocytopenia, respectively.

Conclusion Pre-chemotherapy serum Hcy appeared to correlate with haematological toxicity and may be a useful biomarker for predicting severity of pemetrexed induced haematological toxicity.

Pemetrexed, Vitamin B12, and Thoracic Tumors: The Times, They Are A-Changin'

The administration of pemetrexed requires routine supplementation with vitamin B12 and folate, even if blood concentrations are normal, in order to mitigate its hematologic toxicity. Emerging data suggest that such premedication can be initiated less than 1 week before starting chemotherapy. The current available data on later administration of vitamin B12 in patients with thoracic tumors are placed into a general context, and the possible role of such strategy in the era of immunooncology is discussed.