Avelumab Program Rollover Study

The main purpose of this study is to monitor the safety and tolerability of avelumab in participants with solid tumors who continue treatment with avelumab under the same treatment regimen as in the parent avelumab study.

Inclusion Criteria: * Participants under enrollment and treatment in an avelumab clinical study under the sponsorship of EMD Serono Research \& Development Institute, Inc. / Merck KGaA, Darmstadt, Germany * Merck Serono Co., Ltd (Japan) * Participants currently enrolled in an avelumab parent study and are on active treatment with avelumab or in long-term survival follow-up after treatment * Participants on active treatment must agree to continue to use highly effective contraception (that is, methods with a failure rate of less than 1% per year) for both male and female participants if the risk of conception exists * Other protocol defined inclusion criteria could apply. Exclusion Criteria: * Participants who are pregnant or breastfeeding * Participants still on active treatment: Known hypersensitivity to any of the study intervention ingredients * Participant has been enrolled in the comparator arm of avelumab parent study * Participant has been withdrawn from avelumab parent study for any reason * Any other reason that, in the opinion of the Investigator, precludes the participant from participating in the study * Other protocol defined exclusion criteria could apply.