Locally-directed radiotherapy has been reported by Victorian clinicians to boost the effect of systemic PD-1 inhibition in refractory classical Hodgkin lymphoma.
A case study of a 24-year-old male with disease progression despite multiple therapies including nivolumab, appears to show an abscopal effect from radiation therapy to infradiaphragmatic sites.
“Repeat PET/CT 6 weeks postradiotherapy demonstrated complete response in almost all areas of disease, both within, and outside the radiotherapy field, including the left pulmonary hilar, left parotid and right cervical nodal areas,” the report said.
“Only one site in the left axilla failed to respond completely which was irradiated 1 month later. A subsequent PET/CT 2 months later showed a complete metabolic response, with only minor inflammatory nodal uptake at the right pulmonary hilum.”
The authors said they believed it was only the second report of an abscopal effect in the context of PD-1 inhibition in Hodgkin lymphoma.
Co-author and haematologist Dr Joel Wight, from Austin Health, told the limbic that both treatments were often used for late relapse but there have been no studies to show they can be synergistic.
“It’s uncommon but it’s potentially going to be more important the more we get into immune therapy because the postulated mechanism is immune-mediated killing of tumour cells.”
“I think the main clinical take-home point is that if you have a patient for whom the PD-1 inhibition has been either a last line or their most effective line of therapy, at the point of progression consider adjunctive therapy such as radiation therapy which might augment the response.”
“In chemo, when it stops working and you have progressive disease, you just stop but in PD-1 inhibition, because they are immune therapies, the way we need to think about them is different.”
“We need to think about ways we can rescue or salvage people who are progressing on therapy by augmenting responses using novel modalities such as radiation.”
He said radiation was a reasonably non-toxic therapy.
“So if a clinician wants to try it they can even try it at a smaller dose and see if they gain an abscopal effect and if that doesn’t work, potentially increase the dose depending on tolerability. You don’t lose anything by trying a small dose first.”
He said he was aware of clinical trials on the horizon looking at abscopal effects in other diseases such as DLBCL but not in Hodgkin lymphoma.
“And that might just be a feasibility problem as relapsed Hodgkin lymphoma is reasonably uncommon.”
The study was published in Leukemia & Lymphoma.