Disease Parameters Measurable disease: Measurable lesions are define d as those that can be accurately measured in at least one dimension (longest di ameter to be recorded) as >20 mm by chest x-ray, as >10 mm with CT scan, or >10 mm with calipers by clin ical exam. All tumor measurements must be recorded in millimeters (or decimal fractions of centimeters). Note: Tumor lesions that are situated in a prev iously irradiated area might or might not be considered measurable unless there is evid ence of progression in the irradiated site. Malignant lymph nodes. To be considered path ologically enlarged and measurable, a lymph node must be >15 mm in short axis when asse ssed by CT scan (CT scan slice thickness recommended to be no greater th an 5 mm). At baseline and in follow-up, only the short axis will be measured and followed. Non-measurable disease: All other lesions (or si tes of disease), includin g small lesions (longest diameter <10 mm or pat hological lymph nodes with ≥10 to <15 mm short ax is), are considered non-measurable disease. Bone lesions, leptomeni ngeal disease, ascites, pleural/pericardial effusions, lymphangitis cutis/pulmonitis, infla mmatory breast disease, and abdominal masses (not followed by CT or MRI), ar e considered as non-measurable. Note: Cystic lesions that meet the criteria for radiographically defined simple cysts should not be considered as malignant lesions (neith er measurable nor non-measurable) since they are, by definition, simple cysts. ‘Cystic lesions’ thought to represent cystic me tastases can be considered as measurable lesions, if they meet the definition of measurab ility described above. However, if non-cystic lesions are present in the same patient, these ar e preferred for selecti on as target lesions. Target lesions: All measurable lesions up to a maximum of 2 lesions per organ and 5 lesions in total, representative of all involv ed organs, should be identified as target lesions and recorded and measured at baseline. Target lesions should be selected on the basis of their size (lesions with the longest diameter), be representative of all involved organs, but in addition should be those that lend themselves to reproducible repe ated measurements. It may be the case that, on occasion, the largest lesion does not lend itsel f to reproducible measurement in which circumstance the next largest lesion which can be measured reproducibly should be selected. A sum of the diameters (longest fo r non-nodal lesions, short axis fo r nodal lesions) fo r all target lesions will be calculated and re ported as the baseline sum diameters. If lymph nodes are to be Phase 2 Study of GVAX (with CY) and pembrolizum ab in MMR-p advanced colorectal cancer J16154/Version 5/ January 17, 2018 72included in the sum, then only the short axis is added into the sum. The baseline sum diameters will be used as reference to further characteri ze any objective tumor regression in the measurable dimension of the disease. Non-target lesions: All other lesions (or sites of disease) including any measurable lesions over and above the 5 target lesions should be identified as non-target lesions and should also be recorded at baseline. Measurements of these le sions are not required, but the presence, absence, or in rare cases unequivocal progression of each should be noted throughout follow-up. Evaluation of Target Lesions Complete Response (CR): Disappearance of all target lesions. Any pathological lymph nodes (whether target or non-target) must ha ve reduction in shor t axis to <10 mm. Partial Response (PR): At least a 30% decrease in the sum of the diameters of target lesions, taking as reference the baseline sum diameters. Progressive Disease (PD): At least a 20% increase in the sum of the diameters of target lesions, taking as reference the smallest sum on study (this includes the baseline sum if that is the smallest on study). In addition to the relative incr ease of 20%, the sum must also demonstrate an absolute increase of at least 5 mm. (Note: the a ppearance of one or more new lesions is also considered progressions). Stable Disease (SD): Neither sufficient shrinkage to qualify for PR nor sufficient increase to qualify for PD, taking as reference the smallest sum diameters while on study. Evaluation of Non-Target Lesions Complete Response (CR): Disappearance of all no n-target lesions and no rmalization of tumor marker level. All lymph nodes must be non- pathological in size (<10 mm short axis). Note: If tumor markers are in itially above the upper normal limit, they must normalize for a patient to be considered in complete clinical response. Non-CR/Non-PD: Persistence of one or more non-target lesion(s) and/or maintenance of tumor marker level above the normal limits. Progressive Disease (PD): Appearance of one or more new lesions and/or unequivocal progression of existing non-target lesions. Unequivocal progression should not normally trump target lesion status. It must be representative of overall disease status ch ange, not a single lesion increase. Although a clear progression of “ non-target” lesions on ly is exceptional, the opinion of the Phase 2 Study of GVAX (with CY) and pembrolizum ab in MMR-p advanced colorectal cancer J16154/Version 5/ January 17, 2018 73treating physician should prevail in such circumstances, and th e progression status should be confirmed at a later time by the review panel (or Principa l Investigator). Evaluation of Best Overall Response The best overall response is th e best response recorded from th e start of the treatment until disease progression/recurrence (taking as refe rence for progressive disease the smallest measurements recorded since the treatment started). The patient's best response assignment will depend on the achievement of both meas urement and confirmation criteria. For Patients with Measurable Disease (i.e., Target Disease) Target Lesions Non-Target Lesions New Lesions Overall ResponseBest Overall Response when Confirmation is Required* CR CR No CR >4 wks. Confirmation** CR Non-CR/Non- PD No PR >4 wks. Confirmation** CR Not evaluated No PR PR Non-CR/Non- PD/not evaluated No PR SD Non-CR/Non- PD/not evaluated No SD Documented at least once >4 wks. from baseline** PD Any Yes or No PD no prior SD, PR or CR Any PD*** Yes or No PD Any Any Yes PD * See RECIST 1.1 manuscript for furthe r details on what is evidence of a new lesion. ** Only for non-randomized trials wi th response as primary endpoint. *** In exceptional circumstances, une quivocal progression in non-target lesions may be accepted as disease progression. Note: Patients with a global deterior ation of health status requiring discontinuation of treatment wit hout objective evidence of disease progression at that time should be reported as “ symptomatic deterioration.” Every effort should be made to document the objective progression even after disc ontinuation of treatment. Phase 2 Study of GVAX (with CY) and pembrolizum ab in MMR-p advanced colorectal cancer J16154/Version 5/ January 17, 2018 74Reference E.A. Eisenhauer, P.