Saturday, October 17, 2015
Review of abscopal responses after radiotherapy in melanoma patients
A systematic review of abscopal responses following radiotherapy in patients with metastatic melanoma treated with ipilimumab. Chandra, Wilhite, Balboni, et al. Oncoimmunology. May 2015.
"Case reports and preclinical data suggest radiotherapy and immunotherapy may synergize to generate 'abscopal' responses outside the radiation field. This phenomenon remains relatively unexplored.... We evaluated 47 consecutive metastatic melanoma patients treated with ipi and 65 courses of radiation. Responses of index lesions outside the radiation field were compared before and after radiotherapy... Median survival was 28 months, with an estimated 20% of 5 year survival. Index lesions shrank in 7 instances prior to radiation therapy (11%), compared with 16 instances after radiation therapy (25%); in 11 of the later instances (69%), the index lesion had been increasing in size prior to radiotherapy. In 68% of cases, radiotherapy was associated with an improved rate of index lesion response.... Our...review...suggests that a subset of patients may have more favorable out-of-field responses following treatment with radiation. Interestingly, we found that multiple fraction radiation regimens were associated with a more favorable response. These results are encouraging regarding potential synergies between radiation and immunotherapy, but suggest that attention and even prospective testing of radiation parameters critical to producing abscopal effects...would be of value."
Cool! Now keep in mind that this is talking about 'abscopal' responses....not just a general enhancement of effectiveness when immunotherapy is combined with radiation....as this post was referring to: Why immunotherapy is better with radiotherapy....
Here's an early post about abscopal responses: Abscopal effects of radiotherapy
An older post about ipi, radiation, increased effect and abscopal responses: ipi and radiation: a good combo for melanoma
Finally, there have also been abscopal responses noted with intralesional therapy...which do not involve radiation: asco 2015: intralesional therapy for melanoma
Obviously, there is much more to learn about the mechanisms that come into play when immunotherapy and radiation are combined...both for generally increased benefit and abscopal responses in particular. At least folks are now paying attention and trying to figure it out rather than arguing about whether it is real. Hang in there, ratties. You have taught us all amazing things! - c