For seven months, three-year-old Emil Abbasov underwent chemotherapy to fight the tangerine-sized, cancerous tumor growing in his abdomen. But each time, the tumor resisted harder. Each time, he felt more treatment side effects.

Surgery helped remove some of the tumor, but not enough. So doctors at the University of Michigan’s C.S. Mott Children’s Hospital took a new approach, combining immunotherapy and chemotherapy in a nonconventional way.

After 17 rounds of the combination treatment, Emil’s tumor was completely gone.

The now-first grader is among a group of patients with hard-to-treat neuroblastoma who responded so well to the novel treatment combination in a Children’s Oncology Group international clinical trial that researchers plan to expand the study to include more children. C.S. Mott pediatric oncologist Rajen Mody, M.D., who led the research, recently presented the preliminary findings at the American Society of Clinical Oncology meeting.

When standard therapies don’t work, as in Emil’s case, or the cancer returns, the battle against the disease is grim — less than 5 percent of these young patients survive.

After the first year of receiving the novel treatment combination in the COG trial, 9 out of 17 children with relapsed neuroblastoma saw either a complete or partial remission — a 53 percent response rate compared to the typical 10 to 12 percent response rate from chemotherapy or biologic therapy alone.

“The outcomes for relapsed neuroblastoma are dismal, and treatment options are limited,” Mody says. “We found that in more than half of patients receiving this new combination therapy, the tumor either shrank or completely disappeared, which we consider an extraordinary success. Our study was small, but the results are so striking, they warrant further research to study the biological basis of why this combination of immunotherapy and chemotherapy works so well.”

The phase II COG trial involved 35 patients, but researchers are planning to open a larger form of the trial soon.