Concurrent use of multiple low dose chemotherapy agents with differing mechanisms of action as a strategy vs passive resistance: A pilot study

Association of a novel point mutation in MSH2 gene with familial multiple primary cancers

Background

Multiple primary cancers (MPC) have been identified as two or more cancers without any subordinate relationship that occur either simultaneously or metachronously in the same or different organs of an individual. Lynch syndrome is an autosomal dominant genetic disorder that increases the risk of many types of cancers. Lynch syndrome patients who suffer more than two cancers can also be considered as MPC; patients of this kind provide unique resources to learn how genetic mutation causes MPC in different tissues.

Methods

We performed a whole genome sequencing on blood cells and two tumor samples of a Lynch syndrome patient who was diagnosed with five primary cancers. The mutational landscape of the tumors, including somatic point mutations and copy number alternations, was characterized. We also compared Lynch syndrome with sporadic cancers and proposed a model to illustrate the mutational process by which Lynch syndrome progresses to MPC.

Results

We revealed a novel pathologic mutation on the MSH2 gene (G504 splicing) that associates with Lynch syndrome. Systematical comparison of the mutation landscape revealed that multiple cancers in the proband were evolutionarily independent. Integrative analysis showed that truncating mutations of DNA mismatch repair (MMR) genes were significantly enriched in the patient. A mutation progress model that included germline mutations of MMR genes, double hits of MMR system, mutations in tissue-specific driver genes, and rapid accumulation of additional passenger mutations was proposed to illustrate how MPC occurs in Lynch syndrome patients.

Conclusion

Our findings demonstrate that both germline and somatic alterations are driving forces of carcinogenesis, which may resolve the carcinogenic theory of Lynch syndrome.

Electronic supplementary material

The online version of this article (10.1186/s13045-017-0523-y) contains supplementary material, which is available to authorized users.

Phase II study of alternating chemotherapy regimens for advanced non-small cell lung cancer

PURPOSE

We assessed the use of alternating drugs with differing mechanisms of action as treatment for advanced non-small cell lung cancer.

BACKGROUND

We hypothesized that the shape of a dose-response curve would be determined by the major mechanisms of resistance of a cancer to the drug being studied. Assessment of data from published clinical trials suggested that if our hypothesis were correct resistance of non-small cell lung cancer to most agents is due to "saturable passive" resistance mechanisms (non-competitive inhibition of drug effect due to deficiency of a factor required for drug effect) rather than to "active" resistance mechanisms (competitive inhibition of drug effect due to excess of a factor) or to "non-saturable passive resistance (due to factor alteration or mutation). Using drugs with differing mechanisms of action is a strategy that might be of value against passive resistance.

METHOD

In patients with advanced non-small cell lung cancer, we used four alternating cisplatin-based regimens. In each regimen, cisplatin 80 mg/m(2) was given iv on day 1 of each course. The regimens were: cisplatin + vinorelbine 25 mg/m(2) days 1, 8 and 15, cisplatin + gemcitabine 1000 mg/m(2) days 1, 8 and 15, cisplatin + paclitaxel 200 mg/m(2) day 1 iv over 1h, and cisplatin + etoposide 100 mg/m(2) po days 1-6. Patients were assigned randomly to different regimen sequences. Patients first received 1 course of each of these 4 regimens, then received 1 further course of each of single agent vinorelbine, gemcitabine, paclitaxel and etoposide (at the same doses as in courses 1-4), without cisplatin. (Cisplatin was omitted from courses 5-8 to limit cumulative toxicity.) Change in tumor size was measured after each course.

RESULTS

Thirty-six patients were entered. One patient achieved complete remission and nine achieved partial remissions, for an objective response rate of 28% (95% confidence intervals, 13-43%). Nineteen patients (53%) (95% confidence intervals, 37-69%) had stable disease. Eleven patients had growth of >10% on one regimen followed by tumor shrinkage of >10% on a later one. Median survival was 8.1 months, 1-year survival was 28% and 2-year survival was 6%. No unexpected toxicity was seen.

CONCLUSIONS

The use of four alternating regimens is feasible in advanced non-small cell lung cancer. Response rates and survival times were comparable to those observed for standard chemotherapy approaches, suggesting that this strategy does not offer any major advantage. We plan to explore the hypothesis that this approach failed since tumor cells surviving first exposure to chemotherapy rapidly down-regulate their ability to undergo apoptosis.