Three Fraction Radiation to Induce Immuno-Oncologic Response

Official Title

Evaluating the Use of Stereotactic Radiation Therapy Prior to Neoadjuvant Chemotherapy for High-risk Breast Carcinoma (a SIGNAL Series Clinical Trial): Three Fraction Radiation to Induce Immuno-Oncologic Response (TRIO Trial)


Patients with high risk breast cancers (any locally advanced breast cancer patient defined as Stages IIB-III [excluding inflammatory breast cancer] with stage IIA being eligible for triple negative and HER2-positive breast cancers) will receive neoadjuvant radiation to any portion of their tumour in three fractions in order to act as an immune primer. Radiation will be delivered to a portion of the tumour in three fractions. The patient will be positioned prone as per the SIGNAL 2.0 protocol. The patient will then go on to standard of care treatment (neoadjuvant chemotherapy and surgery) followed by whole-breast radiation as needed. Pathologic complete response will be the primary outcome. Immune markers will also be evaluated.

Trial Description

Primary Outcome:

  • Pathologic complete response
Secondary Outcome:
  • Response rates in the primary post chemotherapy by imaging
  • Response rates in the axillary nodes post chemotherapy by imaging and pathology
  • Immune priming
  • Radiation toxicity
  • Surgical wound healing and the overall complication rate.
  • Local recurrence rates
  • Ability of imaging to predict patient response to radiation therapy.
  • Ability of imaging markers to predict response to radiation therapy
  • Ability to predict pathological response to treatment based on tumour genetics
Patients eligible for neoadjuvant chemotherapy for locally advanced stage III (non-inflammatory) breast cancer or stage IIb (triple negative or Her2+) breast cancers will be approached to participate in this single arm trial. Patients with staging investigations ruling out distant disease will be approached to participate and will undergo pre-treatment image guided core biopsy and blood samples for molecular correlative studies, followed by hypofractionated radiation (delivered prone) to entire tumour with dose constraints to skin, critical organs and contralateral breast, plus a 0.5 cm PTV. As much of the tumour that can receive planned dose of 8 Gy per fraction x 3 fractions every second day, with fall off dose to 4 Gy per fraction x 3 fractions for PTV margin. Two weeks following completion of radiation, patients will undergo a second image guided core needle biopsy of tumour and blood sample. They will then begin standard neoadjuvant chemotherapy (anthracycline and taxane based), followed by a third tissue biopsy under image guidance of any residual tumour and blood sample and then standard surgery (breast conserving or lumpectomy). This will be followed by standard whole breast radiation (50 Gy in 25 fractions). Herceptin therapy and hormonal therapy will be administered as per clinical standard when indicated. Primary outcome will be measured as pathological complete response to treatment, and secondary outcomes will include toxicity, immune markers (tumour infiltrating lymphocytes, PD-1 and PD-L1 up-regulation and changes to the circulating lymphocyte counts.

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Canadian Cancer Society

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